Initial import

14 files changed, 8810 insertions, 0 deletions

diff --git a/drivers/hv/Kconfig b/drivers/hv/Kconfig
new file mode 100644
index 000000000..0403b51d2
--- /dev/null
+++ b/drivers/hv/Kconfig
@@ -0,0 +1,22 @@
+menu "Microsoft Hyper-V guest support"
+
+config HYPERV
+	tristate "Microsoft Hyper-V client drivers"
+	depends on X86 && ACPI && PCI && X86_LOCAL_APIC && HYPERVISOR_GUEST
+	help
+	  Select this option to run Linux as a Hyper-V client operating
+	  system.
+
+config HYPERV_UTILS
+	tristate "Microsoft Hyper-V Utilities driver"
+	depends on HYPERV && CONNECTOR && NLS
+	help
+	  Select this option to enable the Hyper-V Utilities.
+
+config HYPERV_BALLOON
+	tristate "Microsoft Hyper-V Balloon driver"
+	depends on HYPERV
+	help
+	  Select this option to enable Hyper-V Balloon driver.
+
+endmenu
diff --git a/drivers/hv/Makefile b/drivers/hv/Makefile
new file mode 100644
index 000000000..5e4dfa4cf
--- /dev/null
+++ b/drivers/hv/Makefile
@@ -0,0 +1,8 @@
+obj-$(CONFIG_HYPERV)		+= hv_vmbus.o
+obj-$(CONFIG_HYPERV_UTILS)	+= hv_utils.o
+obj-$(CONFIG_HYPERV_BALLOON)	+= hv_balloon.o
+
+hv_vmbus-y := vmbus_drv.o \
+		 hv.o connection.o channel.o \
+		 channel_mgmt.o ring_buffer.o
+hv_utils-y := hv_util.o hv_kvp.o hv_snapshot.o hv_fcopy.o
diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
new file mode 100644
index 000000000..54da66dc7
--- /dev/null
+++ b/drivers/hv/channel.c
@@ -0,0 +1,956 @@
+/*
+ * Copyright (c) 2009, Microsoft Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
+ * Place - Suite 330, Boston, MA 02111-1307 USA.
+ *
+ * Authors:
+ *   Haiyang Zhang <haiyangz@microsoft.com>
+ *   Hank Janssen  <hjanssen@microsoft.com>
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/wait.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/hyperv.h>
+#include <linux/uio.h>
+
+#include "hyperv_vmbus.h"
+
+#define NUM_PAGES_SPANNED(addr, len) \
+((PAGE_ALIGN(addr + len) >> PAGE_SHIFT) - (addr >> PAGE_SHIFT))
+
+/*
+ * vmbus_setevent- Trigger an event notification on the specified
+ * channel.
+ */
+static void vmbus_setevent(struct vmbus_channel *channel)
+{
+	struct hv_monitor_page *monitorpage;
+
+	if (channel->offermsg.monitor_allocated) {
+		/* Each u32 represents 32 channels */
+		sync_set_bit(channel->offermsg.child_relid & 31,
+			(unsigned long *) vmbus_connection.send_int_page +
+			(channel->offermsg.child_relid >> 5));
+
+		/* Get the child to parent monitor page */
+		monitorpage = vmbus_connection.monitor_pages[1];
+
+		sync_set_bit(channel->monitor_bit,
+			(unsigned long *)&monitorpage->trigger_group
+					[channel->monitor_grp].pending);
+
+	} else {
+		vmbus_set_event(channel);
+	}
+}
+
+/*
+ * vmbus_open - Open the specified channel.
+ */
+int vmbus_open(struct vmbus_channel *newchannel, u32 send_ringbuffer_size,
+		     u32 recv_ringbuffer_size, void *userdata, u32 userdatalen,
+		     void (*onchannelcallback)(void *context), void *context)
+{
+	struct vmbus_channel_open_channel *open_msg;
+	struct vmbus_channel_msginfo *open_info = NULL;
+	void *in, *out;
+	unsigned long flags;
+	int ret, err = 0;
+	unsigned long t;
+
+	spin_lock_irqsave(&newchannel->lock, flags);
+	if (newchannel->state == CHANNEL_OPEN_STATE) {
+		newchannel->state = CHANNEL_OPENING_STATE;
+	} else {
+		spin_unlock_irqrestore(&newchannel->lock, flags);
+		return -EINVAL;
+	}
+	spin_unlock_irqrestore(&newchannel->lock, flags);
+
+	newchannel->onchannel_callback = onchannelcallback;
+	newchannel->channel_callback_context = context;
+
+	/* Allocate the ring buffer */
+	out = (void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO,
+		get_order(send_ringbuffer_size + recv_ringbuffer_size));
+
+	if (!out) {
+		err = -ENOMEM;
+		goto error0;
+	}
+
+	in = (void *)((unsigned long)out + send_ringbuffer_size);
+
+	newchannel->ringbuffer_pages = out;
+	newchannel->ringbuffer_pagecount = (send_ringbuffer_size +
+					   recv_ringbuffer_size) >> PAGE_SHIFT;
+
+	ret = hv_ringbuffer_init(
+		&newchannel->outbound, out, send_ringbuffer_size);
+
+	if (ret != 0) {
+		err = ret;
+		goto error0;
+	}
+
+	ret = hv_ringbuffer_init(
+		&newchannel->inbound, in, recv_ringbuffer_size);
+	if (ret != 0) {
+		err = ret;
+		goto error0;
+	}
+
+
+	/* Establish the gpadl for the ring buffer */
+	newchannel->ringbuffer_gpadlhandle = 0;
+
+	ret = vmbus_establish_gpadl(newchannel,
+					 newchannel->outbound.ring_buffer,
+					 send_ringbuffer_size +
+					 recv_ringbuffer_size,
+					 &newchannel->ringbuffer_gpadlhandle);
+
+	if (ret != 0) {
+		err = ret;
+		goto error0;
+	}
+
+	/* Create and init the channel open message */
+	open_info = kmalloc(sizeof(*open_info) +
+			   sizeof(struct vmbus_channel_open_channel),
+			   GFP_KERNEL);
+	if (!open_info) {
+		err = -ENOMEM;
+		goto error_gpadl;
+	}
+
+	init_completion(&open_info->waitevent);
+
+	open_msg = (struct vmbus_channel_open_channel *)open_info->msg;
+	open_msg->header.msgtype = CHANNELMSG_OPENCHANNEL;
+	open_msg->openid = newchannel->offermsg.child_relid;
+	open_msg->child_relid = newchannel->offermsg.child_relid;
+	open_msg->ringbuffer_gpadlhandle = newchannel->ringbuffer_gpadlhandle;
+	open_msg->downstream_ringbuffer_pageoffset = send_ringbuffer_size >>
+						  PAGE_SHIFT;
+	open_msg->target_vp = newchannel->target_vp;
+
+	if (userdatalen > MAX_USER_DEFINED_BYTES) {
+		err = -EINVAL;
+		goto error_gpadl;
+	}
+
+	if (userdatalen)
+		memcpy(open_msg->userdata, userdata, userdatalen);
+
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+	list_add_tail(&open_info->msglistentry,
+		      &vmbus_connection.chn_msg_list);
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+
+	ret = vmbus_post_msg(open_msg,
+			       sizeof(struct vmbus_channel_open_channel));
+
+	if (ret != 0) {
+		err = ret;
+		goto error1;
+	}
+
+	t = wait_for_completion_timeout(&open_info->waitevent, 5*HZ);
+	if (t == 0) {
+		err = -ETIMEDOUT;
+		goto error1;
+	}
+
+
+	if (open_info->response.open_result.status)
+		err = open_info->response.open_result.status;
+
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+	list_del(&open_info->msglistentry);
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+
+	if (err == 0)
+		newchannel->state = CHANNEL_OPENED_STATE;
+
+	kfree(open_info);
+	return err;
+
+error1:
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+	list_del(&open_info->msglistentry);
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+
+error_gpadl:
+	vmbus_teardown_gpadl(newchannel, newchannel->ringbuffer_gpadlhandle);
+
+error0:
+	free_pages((unsigned long)out,
+		get_order(send_ringbuffer_size + recv_ringbuffer_size));
+	kfree(open_info);
+	newchannel->state = CHANNEL_OPEN_STATE;
+	return err;
+}
+EXPORT_SYMBOL_GPL(vmbus_open);
+
+/*
+ * create_gpadl_header - Creates a gpadl for the specified buffer
+ */
+static int create_gpadl_header(void *kbuffer, u32 size,
+					 struct vmbus_channel_msginfo **msginfo,
+					 u32 *messagecount)
+{
+	int i;
+	int pagecount;
+	struct vmbus_channel_gpadl_header *gpadl_header;
+	struct vmbus_channel_gpadl_body *gpadl_body;
+	struct vmbus_channel_msginfo *msgheader;
+	struct vmbus_channel_msginfo *msgbody = NULL;
+	u32 msgsize;
+
+	int pfnsum, pfncount, pfnleft, pfncurr, pfnsize;
+
+	pagecount = size >> PAGE_SHIFT;
+
+	/* do we need a gpadl body msg */
+	pfnsize = MAX_SIZE_CHANNEL_MESSAGE -
+		  sizeof(struct vmbus_channel_gpadl_header) -
+		  sizeof(struct gpa_range);
+	pfncount = pfnsize / sizeof(u64);
+
+	if (pagecount > pfncount) {
+		/* we need a gpadl body */
+		/* fill in the header */
+		msgsize = sizeof(struct vmbus_channel_msginfo) +
+			  sizeof(struct vmbus_channel_gpadl_header) +
+			  sizeof(struct gpa_range) + pfncount * sizeof(u64);
+		msgheader =  kzalloc(msgsize, GFP_KERNEL);
+		if (!msgheader)
+			goto nomem;
+
+		INIT_LIST_HEAD(&msgheader->submsglist);
+		msgheader->msgsize = msgsize;
+
+		gpadl_header = (struct vmbus_channel_gpadl_header *)
+			msgheader->msg;
+		gpadl_header->rangecount = 1;
+		gpadl_header->range_buflen = sizeof(struct gpa_range) +
+					 pagecount * sizeof(u64);
+		gpadl_header->range[0].byte_offset = 0;
+		gpadl_header->range[0].byte_count = size;
+		for (i = 0; i < pfncount; i++)
+			gpadl_header->range[0].pfn_array[i] = slow_virt_to_phys(
+				kbuffer + PAGE_SIZE * i) >> PAGE_SHIFT;
+		*msginfo = msgheader;
+		*messagecount = 1;
+
+		pfnsum = pfncount;
+		pfnleft = pagecount - pfncount;
+
+		/* how many pfns can we fit */
+		pfnsize = MAX_SIZE_CHANNEL_MESSAGE -
+			  sizeof(struct vmbus_channel_gpadl_body);
+		pfncount = pfnsize / sizeof(u64);
+
+		/* fill in the body */
+		while (pfnleft) {
+			if (pfnleft > pfncount)
+				pfncurr = pfncount;
+			else
+				pfncurr = pfnleft;
+
+			msgsize = sizeof(struct vmbus_channel_msginfo) +
+				  sizeof(struct vmbus_channel_gpadl_body) +
+				  pfncurr * sizeof(u64);
+			msgbody = kzalloc(msgsize, GFP_KERNEL);
+
+			if (!msgbody) {
+				struct vmbus_channel_msginfo *pos = NULL;
+				struct vmbus_channel_msginfo *tmp = NULL;
+				/*
+				 * Free up all the allocated messages.
+				 */
+				list_for_each_entry_safe(pos, tmp,
+					&msgheader->submsglist,
+					msglistentry) {
+
+					list_del(&pos->msglistentry);
+					kfree(pos);
+				}
+
+				goto nomem;
+			}
+
+			msgbody->msgsize = msgsize;
+			(*messagecount)++;
+			gpadl_body =
+				(struct vmbus_channel_gpadl_body *)msgbody->msg;
+
+			/*
+			 * Gpadl is u32 and we are using a pointer which could
+			 * be 64-bit
+			 * This is governed by the guest/host protocol and
+			 * so the hypervisor gurantees that this is ok.
+			 */
+			for (i = 0; i < pfncurr; i++)
+				gpadl_body->pfn[i] = slow_virt_to_phys(
+					kbuffer + PAGE_SIZE * (pfnsum + i)) >>
+					PAGE_SHIFT;
+
+			/* add to msg header */
+			list_add_tail(&msgbody->msglistentry,
+				      &msgheader->submsglist);
+			pfnsum += pfncurr;
+			pfnleft -= pfncurr;
+		}
+	} else {
+		/* everything fits in a header */
+		msgsize = sizeof(struct vmbus_channel_msginfo) +
+			  sizeof(struct vmbus_channel_gpadl_header) +
+			  sizeof(struct gpa_range) + pagecount * sizeof(u64);
+		msgheader = kzalloc(msgsize, GFP_KERNEL);
+		if (msgheader == NULL)
+			goto nomem;
+		msgheader->msgsize = msgsize;
+
+		gpadl_header = (struct vmbus_channel_gpadl_header *)
+			msgheader->msg;
+		gpadl_header->rangecount = 1;
+		gpadl_header->range_buflen = sizeof(struct gpa_range) +
+					 pagecount * sizeof(u64);
+		gpadl_header->range[0].byte_offset = 0;
+		gpadl_header->range[0].byte_count = size;
+		for (i = 0; i < pagecount; i++)
+			gpadl_header->range[0].pfn_array[i] = slow_virt_to_phys(
+				kbuffer + PAGE_SIZE * i) >> PAGE_SHIFT;
+
+		*msginfo = msgheader;
+		*messagecount = 1;
+	}
+
+	return 0;
+nomem:
+	kfree(msgheader);
+	kfree(msgbody);
+	return -ENOMEM;
+}
+
+/*
+ * vmbus_establish_gpadl - Estabish a GPADL for the specified buffer
+ *
+ * @channel: a channel
+ * @kbuffer: from kmalloc or vmalloc
+ * @size: page-size multiple
+ * @gpadl_handle: some funky thing
+ */
+int vmbus_establish_gpadl(struct vmbus_channel *channel, void *kbuffer,
+			       u32 size, u32 *gpadl_handle)
+{
+	struct vmbus_channel_gpadl_header *gpadlmsg;
+	struct vmbus_channel_gpadl_body *gpadl_body;
+	struct vmbus_channel_msginfo *msginfo = NULL;
+	struct vmbus_channel_msginfo *submsginfo;
+	u32 msgcount;
+	struct list_head *curr;
+	u32 next_gpadl_handle;
+	unsigned long flags;
+	int ret = 0;
+
+	next_gpadl_handle =
+		(atomic_inc_return(&vmbus_connection.next_gpadl_handle) - 1);
+
+	ret = create_gpadl_header(kbuffer, size, &msginfo, &msgcount);
+	if (ret)
+		return ret;
+
+	init_completion(&msginfo->waitevent);
+
+	gpadlmsg = (struct vmbus_channel_gpadl_header *)msginfo->msg;
+	gpadlmsg->header.msgtype = CHANNELMSG_GPADL_HEADER;
+	gpadlmsg->child_relid = channel->offermsg.child_relid;
+	gpadlmsg->gpadl = next_gpadl_handle;
+
+
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+	list_add_tail(&msginfo->msglistentry,
+		      &vmbus_connection.chn_msg_list);
+
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+
+	ret = vmbus_post_msg(gpadlmsg, msginfo->msgsize -
+			       sizeof(*msginfo));
+	if (ret != 0)
+		goto cleanup;
+
+	if (msgcount > 1) {
+		list_for_each(curr, &msginfo->submsglist) {
+
+			submsginfo = (struct vmbus_channel_msginfo *)curr;
+			gpadl_body =
+			     (struct vmbus_channel_gpadl_body *)submsginfo->msg;
+
+			gpadl_body->header.msgtype =
+				CHANNELMSG_GPADL_BODY;
+			gpadl_body->gpadl = next_gpadl_handle;
+
+			ret = vmbus_post_msg(gpadl_body,
+					       submsginfo->msgsize -
+					       sizeof(*submsginfo));
+			if (ret != 0)
+				goto cleanup;
+
+		}
+	}
+	wait_for_completion(&msginfo->waitevent);
+
+	/* At this point, we received the gpadl created msg */
+	*gpadl_handle = gpadlmsg->gpadl;
+
+cleanup:
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+	list_del(&msginfo->msglistentry);
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+
+	kfree(msginfo);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(vmbus_establish_gpadl);
+
+/*
+ * vmbus_teardown_gpadl -Teardown the specified GPADL handle
+ */
+int vmbus_teardown_gpadl(struct vmbus_channel *channel, u32 gpadl_handle)
+{
+	struct vmbus_channel_gpadl_teardown *msg;
+	struct vmbus_channel_msginfo *info;
+	unsigned long flags;
+	int ret;
+
+	info = kmalloc(sizeof(*info) +
+		       sizeof(struct vmbus_channel_gpadl_teardown), GFP_KERNEL);
+	if (!info)
+		return -ENOMEM;
+
+	init_completion(&info->waitevent);
+
+	msg = (struct vmbus_channel_gpadl_teardown *)info->msg;
+
+	msg->header.msgtype = CHANNELMSG_GPADL_TEARDOWN;
+	msg->child_relid = channel->offermsg.child_relid;
+	msg->gpadl = gpadl_handle;
+
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+	list_add_tail(&info->msglistentry,
+		      &vmbus_connection.chn_msg_list);
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+	ret = vmbus_post_msg(msg,
+			       sizeof(struct vmbus_channel_gpadl_teardown));
+
+	if (ret)
+		goto post_msg_err;
+
+	wait_for_completion(&info->waitevent);
+
+post_msg_err:
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+	list_del(&info->msglistentry);
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+
+	kfree(info);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(vmbus_teardown_gpadl);
+
+static void reset_channel_cb(void *arg)
+{
+	struct vmbus_channel *channel = arg;
+
+	channel->onchannel_callback = NULL;
+}
+
+static int vmbus_close_internal(struct vmbus_channel *channel)
+{
+	struct vmbus_channel_close_channel *msg;
+	int ret;
+
+	channel->state = CHANNEL_OPEN_STATE;
+	channel->sc_creation_callback = NULL;
+	/* Stop callback and cancel the timer asap */
+	if (channel->target_cpu != get_cpu()) {
+		put_cpu();
+		smp_call_function_single(channel->target_cpu, reset_channel_cb,
+					 channel, true);
+	} else {
+		reset_channel_cb(channel);
+		put_cpu();
+	}
+
+	/* Send a closing message */
+
+	msg = &channel->close_msg.msg;
+
+	msg->header.msgtype = CHANNELMSG_CLOSECHANNEL;
+	msg->child_relid = channel->offermsg.child_relid;
+
+	ret = vmbus_post_msg(msg, sizeof(struct vmbus_channel_close_channel));
+
+	if (ret) {
+		pr_err("Close failed: close post msg return is %d\n", ret);
+		/*
+		 * If we failed to post the close msg,
+		 * it is perhaps better to leak memory.
+		 */
+		return ret;
+	}
+
+	/* Tear down the gpadl for the channel's ring buffer */
+	if (channel->ringbuffer_gpadlhandle) {
+		ret = vmbus_teardown_gpadl(channel,
+					   channel->ringbuffer_gpadlhandle);
+		if (ret) {
+			pr_err("Close failed: teardown gpadl return %d\n", ret);
+			/*
+			 * If we failed to teardown gpadl,
+			 * it is perhaps better to leak memory.
+			 */
+			return ret;
+		}
+	}
+
+	/* Cleanup the ring buffers for this channel */
+	hv_ringbuffer_cleanup(&channel->outbound);
+	hv_ringbuffer_cleanup(&channel->inbound);
+
+	free_pages((unsigned long)channel->ringbuffer_pages,
+		get_order(channel->ringbuffer_pagecount * PAGE_SIZE));
+
+	/*
+	 * If the channel has been rescinded; process device removal.
+	 */
+	if (channel->rescind)
+		hv_process_channel_removal(channel,
+					   channel->offermsg.child_relid);
+	return ret;
+}
+
+/*
+ * vmbus_close - Close the specified channel
+ */
+void vmbus_close(struct vmbus_channel *channel)
+{
+	struct list_head *cur, *tmp;
+	struct vmbus_channel *cur_channel;
+
+	if (channel->primary_channel != NULL) {
+		/*
+		 * We will only close sub-channels when
+		 * the primary is closed.
+		 */
+		return;
+	}
+	/*
+	 * Close all the sub-channels first and then close the
+	 * primary channel.
+	 */
+	list_for_each_safe(cur, tmp, &channel->sc_list) {
+		cur_channel = list_entry(cur, struct vmbus_channel, sc_list);
+		if (cur_channel->state != CHANNEL_OPENED_STATE)
+			continue;
+		vmbus_close_internal(cur_channel);
+	}
+	/*
+	 * Now close the primary.
+	 */
+	vmbus_close_internal(channel);
+}
+EXPORT_SYMBOL_GPL(vmbus_close);
+
+int vmbus_sendpacket_ctl(struct vmbus_channel *channel, void *buffer,
+			   u32 bufferlen, u64 requestid,
+			   enum vmbus_packet_type type, u32 flags, bool kick_q)
+{
+	struct vmpacket_descriptor desc;
+	u32 packetlen = sizeof(struct vmpacket_descriptor) + bufferlen;
+	u32 packetlen_aligned = ALIGN(packetlen, sizeof(u64));
+	struct kvec bufferlist[3];
+	u64 aligned_data = 0;
+	int ret;
+	bool signal = false;
+
+
+	/* Setup the descriptor */
+	desc.type = type; /* VmbusPacketTypeDataInBand; */
+	desc.flags = flags; /* VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED; */
+	/* in 8-bytes granularity */
+	desc.offset8 = sizeof(struct vmpacket_descriptor) >> 3;
+	desc.len8 = (u16)(packetlen_aligned >> 3);
+	desc.trans_id = requestid;
+
+	bufferlist[0].iov_base = &desc;
+	bufferlist[0].iov_len = sizeof(struct vmpacket_descriptor);
+	bufferlist[1].iov_base = buffer;
+	bufferlist[1].iov_len = bufferlen;
+	bufferlist[2].iov_base = &aligned_data;
+	bufferlist[2].iov_len = (packetlen_aligned - packetlen);
+
+	ret = hv_ringbuffer_write(&channel->outbound, bufferlist, 3, &signal);
+
+	/*
+	 * Signalling the host is conditional on many factors:
+	 * 1. The ring state changed from being empty to non-empty.
+	 *    This is tracked by the variable "signal".
+	 * 2. The variable kick_q tracks if more data will be placed
+	 *    on the ring. We will not signal if more data is
+	 *    to be placed.
+	 *
+	 * If we cannot write to the ring-buffer; signal the host
+	 * even if we may not have written anything. This is a rare
+	 * enough condition that it should not matter.
+	 */
+	if (((ret == 0) && kick_q && signal) || (ret))
+		vmbus_setevent(channel);
+
+	return ret;
+}
+EXPORT_SYMBOL(vmbus_sendpacket_ctl);
+
+/**
+ * vmbus_sendpacket() - Send the specified buffer on the given channel
+ * @channel: Pointer to vmbus_channel structure.
+ * @buffer: Pointer to the buffer you want to receive the data into.
+ * @bufferlen: Maximum size of what the the buffer will hold
+ * @requestid: Identifier of the request
+ * @type: Type of packet that is being send e.g. negotiate, time
+ * packet etc.
+ *
+ * Sends data in @buffer directly to hyper-v via the vmbus
+ * This will send the data unparsed to hyper-v.
+ *
+ * Mainly used by Hyper-V drivers.
+ */
+int vmbus_sendpacket(struct vmbus_channel *channel, void *buffer,
+			   u32 bufferlen, u64 requestid,
+			   enum vmbus_packet_type type, u32 flags)
+{
+	return vmbus_sendpacket_ctl(channel, buffer, bufferlen, requestid,
+				    type, flags, true);
+}
+EXPORT_SYMBOL(vmbus_sendpacket);
+
+/*
+ * vmbus_sendpacket_pagebuffer_ctl - Send a range of single-page buffer
+ * packets using a GPADL Direct packet type. This interface allows you
+ * to control notifying the host. This will be useful for sending
+ * batched data. Also the sender can control the send flags
+ * explicitly.
+ */
+int vmbus_sendpacket_pagebuffer_ctl(struct vmbus_channel *channel,
+				     struct hv_page_buffer pagebuffers[],
+				     u32 pagecount, void *buffer, u32 bufferlen,
+				     u64 requestid,
+				     u32 flags,
+				     bool kick_q)
+{
+	int ret;
+	int i;
+	struct vmbus_channel_packet_page_buffer desc;
+	u32 descsize;
+	u32 packetlen;
+	u32 packetlen_aligned;
+	struct kvec bufferlist[3];
+	u64 aligned_data = 0;
+	bool signal = false;
+
+	if (pagecount > MAX_PAGE_BUFFER_COUNT)
+		return -EINVAL;
+
+
+	/*
+	 * Adjust the size down since vmbus_channel_packet_page_buffer is the
+	 * largest size we support
+	 */
+	descsize = sizeof(struct vmbus_channel_packet_page_buffer) -
+			  ((MAX_PAGE_BUFFER_COUNT - pagecount) *
+			  sizeof(struct hv_page_buffer));
+	packetlen = descsize + bufferlen;
+	packetlen_aligned = ALIGN(packetlen, sizeof(u64));
+
+	/* Setup the descriptor */
+	desc.type = VM_PKT_DATA_USING_GPA_DIRECT;
+	desc.flags = flags;
+	desc.dataoffset8 = descsize >> 3; /* in 8-bytes grandularity */
+	desc.length8 = (u16)(packetlen_aligned >> 3);
+	desc.transactionid = requestid;
+	desc.rangecount = pagecount;
+
+	for (i = 0; i < pagecount; i++) {
+		desc.range[i].len = pagebuffers[i].len;
+		desc.range[i].offset = pagebuffers[i].offset;
+		desc.range[i].pfn	 = pagebuffers[i].pfn;
+	}
+
+	bufferlist[0].iov_base = &desc;
+	bufferlist[0].iov_len = descsize;
+	bufferlist[1].iov_base = buffer;
+	bufferlist[1].iov_len = bufferlen;
+	bufferlist[2].iov_base = &aligned_data;
+	bufferlist[2].iov_len = (packetlen_aligned - packetlen);
+
+	ret = hv_ringbuffer_write(&channel->outbound, bufferlist, 3, &signal);
+
+	/*
+	 * Signalling the host is conditional on many factors:
+	 * 1. The ring state changed from being empty to non-empty.
+	 *    This is tracked by the variable "signal".
+	 * 2. The variable kick_q tracks if more data will be placed
+	 *    on the ring. We will not signal if more data is
+	 *    to be placed.
+	 *
+	 * If we cannot write to the ring-buffer; signal the host
+	 * even if we may not have written anything. This is a rare
+	 * enough condition that it should not matter.
+	 */
+	if (((ret == 0) && kick_q && signal) || (ret))
+		vmbus_setevent(channel);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(vmbus_sendpacket_pagebuffer_ctl);
+
+/*
+ * vmbus_sendpacket_pagebuffer - Send a range of single-page buffer
+ * packets using a GPADL Direct packet type.
+ */
+int vmbus_sendpacket_pagebuffer(struct vmbus_channel *channel,
+				     struct hv_page_buffer pagebuffers[],
+				     u32 pagecount, void *buffer, u32 bufferlen,
+				     u64 requestid)
+{
+	u32 flags = VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED;
+	return vmbus_sendpacket_pagebuffer_ctl(channel, pagebuffers, pagecount,
+					       buffer, bufferlen, requestid,
+					       flags, true);
+
+}
+EXPORT_SYMBOL_GPL(vmbus_sendpacket_pagebuffer);
+
+/*
+ * vmbus_sendpacket_multipagebuffer - Send a multi-page buffer packet
+ * using a GPADL Direct packet type.
+ * The buffer includes the vmbus descriptor.
+ */
+int vmbus_sendpacket_mpb_desc(struct vmbus_channel *channel,
+			      struct vmbus_packet_mpb_array *desc,
+			      u32 desc_size,
+			      void *buffer, u32 bufferlen, u64 requestid)
+{
+	int ret;
+	u32 packetlen;
+	u32 packetlen_aligned;
+	struct kvec bufferlist[3];
+	u64 aligned_data = 0;
+	bool signal = false;
+
+	packetlen = desc_size + bufferlen;
+	packetlen_aligned = ALIGN(packetlen, sizeof(u64));
+
+	/* Setup the descriptor */
+	desc->type = VM_PKT_DATA_USING_GPA_DIRECT;
+	desc->flags = VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED;
+	desc->dataoffset8 = desc_size >> 3; /* in 8-bytes grandularity */
+	desc->length8 = (u16)(packetlen_aligned >> 3);
+	desc->transactionid = requestid;
+	desc->rangecount = 1;
+
+	bufferlist[0].iov_base = desc;
+	bufferlist[0].iov_len = desc_size;
+	bufferlist[1].iov_base = buffer;
+	bufferlist[1].iov_len = bufferlen;
+	bufferlist[2].iov_base = &aligned_data;
+	bufferlist[2].iov_len = (packetlen_aligned - packetlen);
+
+	ret = hv_ringbuffer_write(&channel->outbound, bufferlist, 3, &signal);
+
+	if (ret == 0 && signal)
+		vmbus_setevent(channel);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(vmbus_sendpacket_mpb_desc);
+
+/*
+ * vmbus_sendpacket_multipagebuffer - Send a multi-page buffer packet
+ * using a GPADL Direct packet type.
+ */
+int vmbus_sendpacket_multipagebuffer(struct vmbus_channel *channel,
+				struct hv_multipage_buffer *multi_pagebuffer,
+				void *buffer, u32 bufferlen, u64 requestid)
+{
+	int ret;
+	struct vmbus_channel_packet_multipage_buffer desc;
+	u32 descsize;
+	u32 packetlen;
+	u32 packetlen_aligned;
+	struct kvec bufferlist[3];
+	u64 aligned_data = 0;
+	bool signal = false;
+	u32 pfncount = NUM_PAGES_SPANNED(multi_pagebuffer->offset,
+					 multi_pagebuffer->len);
+
+	if (pfncount > MAX_MULTIPAGE_BUFFER_COUNT)
+		return -EINVAL;
+
+	/*
+	 * Adjust the size down since vmbus_channel_packet_multipage_buffer is
+	 * the largest size we support
+	 */
+	descsize = sizeof(struct vmbus_channel_packet_multipage_buffer) -
+			  ((MAX_MULTIPAGE_BUFFER_COUNT - pfncount) *
+			  sizeof(u64));
+	packetlen = descsize + bufferlen;
+	packetlen_aligned = ALIGN(packetlen, sizeof(u64));
+
+
+	/* Setup the descriptor */
+	desc.type = VM_PKT_DATA_USING_GPA_DIRECT;
+	desc.flags = VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED;
+	desc.dataoffset8 = descsize >> 3; /* in 8-bytes grandularity */
+	desc.length8 = (u16)(packetlen_aligned >> 3);
+	desc.transactionid = requestid;
+	desc.rangecount = 1;
+
+	desc.range.len = multi_pagebuffer->len;
+	desc.range.offset = multi_pagebuffer->offset;
+
+	memcpy(desc.range.pfn_array, multi_pagebuffer->pfn_array,
+	       pfncount * sizeof(u64));
+
+	bufferlist[0].iov_base = &desc;
+	bufferlist[0].iov_len = descsize;
+	bufferlist[1].iov_base = buffer;
+	bufferlist[1].iov_len = bufferlen;
+	bufferlist[2].iov_base = &aligned_data;
+	bufferlist[2].iov_len = (packetlen_aligned - packetlen);
+
+	ret = hv_ringbuffer_write(&channel->outbound, bufferlist, 3, &signal);
+
+	if (ret == 0 && signal)
+		vmbus_setevent(channel);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(vmbus_sendpacket_multipagebuffer);
+
+/**
+ * vmbus_recvpacket() - Retrieve the user packet on the specified channel
+ * @channel: Pointer to vmbus_channel structure.
+ * @buffer: Pointer to the buffer you want to receive the data into.
+ * @bufferlen: Maximum size of what the the buffer will hold
+ * @buffer_actual_len: The actual size of the data after it was received
+ * @requestid: Identifier of the request
+ *
+ * Receives directly from the hyper-v vmbus and puts the data it received
+ * into Buffer. This will receive the data unparsed from hyper-v.
+ *
+ * Mainly used by Hyper-V drivers.
+ */
+int vmbus_recvpacket(struct vmbus_channel *channel, void *buffer,
+			u32 bufferlen, u32 *buffer_actual_len, u64 *requestid)
+{
+	struct vmpacket_descriptor desc;
+	u32 packetlen;
+	u32 userlen;
+	int ret;
+	bool signal = false;
+
+	*buffer_actual_len = 0;
+	*requestid = 0;
+
+
+	ret = hv_ringbuffer_peek(&channel->inbound, &desc,
+			     sizeof(struct vmpacket_descriptor));
+	if (ret != 0)
+		return 0;
+
+	packetlen = desc.len8 << 3;
+	userlen = packetlen - (desc.offset8 << 3);
+
+	*buffer_actual_len = userlen;
+
+	if (userlen > bufferlen) {
+
+		pr_err("Buffer too small - got %d needs %d\n",
+			   bufferlen, userlen);
+		return -ETOOSMALL;
+	}
+
+	*requestid = desc.trans_id;
+
+	/* Copy over the packet to the user buffer */
+	ret = hv_ringbuffer_read(&channel->inbound, buffer, userlen,
+			     (desc.offset8 << 3), &signal);
+
+	if (signal)
+		vmbus_setevent(channel);
+
+	return 0;
+}
+EXPORT_SYMBOL(vmbus_recvpacket);
+
+/*
+ * vmbus_recvpacket_raw - Retrieve the raw packet on the specified channel
+ */
+int vmbus_recvpacket_raw(struct vmbus_channel *channel, void *buffer,
+			      u32 bufferlen, u32 *buffer_actual_len,
+			      u64 *requestid)
+{
+	struct vmpacket_descriptor desc;
+	u32 packetlen;
+	int ret;
+	bool signal = false;
+
+	*buffer_actual_len = 0;
+	*requestid = 0;
+
+
+	ret = hv_ringbuffer_peek(&channel->inbound, &desc,
+			     sizeof(struct vmpacket_descriptor));
+	if (ret != 0)
+		return 0;
+
+
+	packetlen = desc.len8 << 3;
+
+	*buffer_actual_len = packetlen;
+
+	if (packetlen > bufferlen)
+		return -ENOBUFS;
+
+	*requestid = desc.trans_id;
+
+	/* Copy over the entire packet to the user buffer */
+	ret = hv_ringbuffer_read(&channel->inbound, buffer, packetlen, 0,
+				 &signal);
+
+	if (signal)
+		vmbus_setevent(channel);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(vmbus_recvpacket_raw);
diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
new file mode 100644
index 000000000..0eeb1b3bc
--- /dev/null
+++ b/drivers/hv/channel_mgmt.c
@@ -0,0 +1,862 @@
+/*
+ * Copyright (c) 2009, Microsoft Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
+ * Place - Suite 330, Boston, MA 02111-1307 USA.
+ *
+ * Authors:
+ *   Haiyang Zhang <haiyangz@microsoft.com>
+ *   Hank Janssen  <hjanssen@microsoft.com>
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/wait.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/completion.h>
+#include <linux/hyperv.h>
+
+#include "hyperv_vmbus.h"
+
+/**
+ * vmbus_prep_negotiate_resp() - Create default response for Hyper-V Negotiate message
+ * @icmsghdrp: Pointer to msg header structure
+ * @icmsg_negotiate: Pointer to negotiate message structure
+ * @buf: Raw buffer channel data
+ *
+ * @icmsghdrp is of type &struct icmsg_hdr.
+ * @negop is of type &struct icmsg_negotiate.
+ * Set up and fill in default negotiate response message.
+ *
+ * The fw_version specifies the  framework version that
+ * we can support and srv_version specifies the service
+ * version we can support.
+ *
+ * Mainly used by Hyper-V drivers.
+ */
+bool vmbus_prep_negotiate_resp(struct icmsg_hdr *icmsghdrp,
+				struct icmsg_negotiate *negop, u8 *buf,
+				int fw_version, int srv_version)
+{
+	int icframe_major, icframe_minor;
+	int icmsg_major, icmsg_minor;
+	int fw_major, fw_minor;
+	int srv_major, srv_minor;
+	int i;
+	bool found_match = false;
+
+	icmsghdrp->icmsgsize = 0x10;
+	fw_major = (fw_version >> 16);
+	fw_minor = (fw_version & 0xFFFF);
+
+	srv_major = (srv_version >> 16);
+	srv_minor = (srv_version & 0xFFFF);
+
+	negop = (struct icmsg_negotiate *)&buf[
+		sizeof(struct vmbuspipe_hdr) +
+		sizeof(struct icmsg_hdr)];
+
+	icframe_major = negop->icframe_vercnt;
+	icframe_minor = 0;
+
+	icmsg_major = negop->icmsg_vercnt;
+	icmsg_minor = 0;
+
+	/*
+	 * Select the framework version number we will
+	 * support.
+	 */
+
+	for (i = 0; i < negop->icframe_vercnt; i++) {
+		if ((negop->icversion_data[i].major == fw_major) &&
+		   (negop->icversion_data[i].minor == fw_minor)) {
+			icframe_major = negop->icversion_data[i].major;
+			icframe_minor = negop->icversion_data[i].minor;
+			found_match = true;
+		}
+	}
+
+	if (!found_match)
+		goto fw_error;
+
+	found_match = false;
+
+	for (i = negop->icframe_vercnt;
+		 (i < negop->icframe_vercnt + negop->icmsg_vercnt); i++) {
+		if ((negop->icversion_data[i].major == srv_major) &&
+		   (negop->icversion_data[i].minor == srv_minor)) {
+			icmsg_major = negop->icversion_data[i].major;
+			icmsg_minor = negop->icversion_data[i].minor;
+			found_match = true;
+		}
+	}
+
+	/*
+	 * Respond with the framework and service
+	 * version numbers we can support.
+	 */
+
+fw_error:
+	if (!found_match) {
+		negop->icframe_vercnt = 0;
+		negop->icmsg_vercnt = 0;
+	} else {
+		negop->icframe_vercnt = 1;
+		negop->icmsg_vercnt = 1;
+	}
+
+	negop->icversion_data[0].major = icframe_major;
+	negop->icversion_data[0].minor = icframe_minor;
+	negop->icversion_data[1].major = icmsg_major;
+	negop->icversion_data[1].minor = icmsg_minor;
+	return found_match;
+}
+
+EXPORT_SYMBOL_GPL(vmbus_prep_negotiate_resp);
+
+/*
+ * alloc_channel - Allocate and initialize a vmbus channel object
+ */
+static struct vmbus_channel *alloc_channel(void)
+{
+	static atomic_t chan_num = ATOMIC_INIT(0);
+	struct vmbus_channel *channel;
+
+	channel = kzalloc(sizeof(*channel), GFP_ATOMIC);
+	if (!channel)
+		return NULL;
+
+	channel->id = atomic_inc_return(&chan_num);
+	spin_lock_init(&channel->inbound_lock);
+	spin_lock_init(&channel->lock);
+
+	INIT_LIST_HEAD(&channel->sc_list);
+	INIT_LIST_HEAD(&channel->percpu_list);
+
+	return channel;
+}
+
+/*
+ * free_channel - Release the resources used by the vmbus channel object
+ */
+static void free_channel(struct vmbus_channel *channel)
+{
+	kfree(channel);
+}
+
+static void percpu_channel_enq(void *arg)
+{
+	struct vmbus_channel *channel = arg;
+	int cpu = smp_processor_id();
+
+	list_add_tail(&channel->percpu_list, &hv_context.percpu_list[cpu]);
+}
+
+static void percpu_channel_deq(void *arg)
+{
+	struct vmbus_channel *channel = arg;
+
+	list_del(&channel->percpu_list);
+}
+
+
+void hv_process_channel_removal(struct vmbus_channel *channel, u32 relid)
+{
+	struct vmbus_channel_relid_released msg;
+	unsigned long flags;
+	struct vmbus_channel *primary_channel;
+
+	memset(&msg, 0, sizeof(struct vmbus_channel_relid_released));
+	msg.child_relid = relid;
+	msg.header.msgtype = CHANNELMSG_RELID_RELEASED;
+	vmbus_post_msg(&msg, sizeof(struct vmbus_channel_relid_released));
+
+	if (channel == NULL)
+		return;
+
+	if (channel->target_cpu != get_cpu()) {
+		put_cpu();
+		smp_call_function_single(channel->target_cpu,
+					 percpu_channel_deq, channel, true);
+	} else {
+		percpu_channel_deq(channel);
+		put_cpu();
+	}
+
+	if (channel->primary_channel == NULL) {
+		spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
+		list_del(&channel->listentry);
+		spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
+	} else {
+		primary_channel = channel->primary_channel;
+		spin_lock_irqsave(&primary_channel->lock, flags);
+		list_del(&channel->sc_list);
+		spin_unlock_irqrestore(&primary_channel->lock, flags);
+	}
+	free_channel(channel);
+}
+
+void vmbus_free_channels(void)
+{
+	struct vmbus_channel *channel;
+
+	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
+		vmbus_device_unregister(channel->device_obj);
+		free_channel(channel);
+	}
+}
+
+/*
+ * vmbus_process_offer - Process the offer by creating a channel/device
+ * associated with this offer
+ */
+static void vmbus_process_offer(struct vmbus_channel *newchannel)
+{
+	struct vmbus_channel *channel;
+	bool fnew = true;
+	bool enq = false;
+	unsigned long flags;
+
+	/* Make sure this is a new offer */
+	spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
+
+	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
+		if (!uuid_le_cmp(channel->offermsg.offer.if_type,
+			newchannel->offermsg.offer.if_type) &&
+			!uuid_le_cmp(channel->offermsg.offer.if_instance,
+				newchannel->offermsg.offer.if_instance)) {
+			fnew = false;
+			break;
+		}
+	}
+
+	if (fnew) {
+		list_add_tail(&newchannel->listentry,
+			      &vmbus_connection.chn_list);
+		enq = true;
+	}
+
+	spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
+
+	if (enq) {
+		if (newchannel->target_cpu != get_cpu()) {
+			put_cpu();
+			smp_call_function_single(newchannel->target_cpu,
+						 percpu_channel_enq,
+						 newchannel, true);
+		} else {
+			percpu_channel_enq(newchannel);
+			put_cpu();
+		}
+	}
+	if (!fnew) {
+		/*
+		 * Check to see if this is a sub-channel.
+		 */
+		if (newchannel->offermsg.offer.sub_channel_index != 0) {
+			/*
+			 * Process the sub-channel.
+			 */
+			newchannel->primary_channel = channel;
+			spin_lock_irqsave(&channel->lock, flags);
+			list_add_tail(&newchannel->sc_list, &channel->sc_list);
+			spin_unlock_irqrestore(&channel->lock, flags);
+
+			if (newchannel->target_cpu != get_cpu()) {
+				put_cpu();
+				smp_call_function_single(newchannel->target_cpu,
+							 percpu_channel_enq,
+							 newchannel, true);
+			} else {
+				percpu_channel_enq(newchannel);
+				put_cpu();
+			}
+
+			newchannel->state = CHANNEL_OPEN_STATE;
+			channel->num_sc++;
+			if (channel->sc_creation_callback != NULL)
+				channel->sc_creation_callback(newchannel);
+
+			return;
+		}
+
+		goto err_free_chan;
+	}
+
+	/*
+	 * This state is used to indicate a successful open
+	 * so that when we do close the channel normally, we
+	 * can cleanup properly
+	 */
+	newchannel->state = CHANNEL_OPEN_STATE;
+
+	/*
+	 * Start the process of binding this offer to the driver
+	 * We need to set the DeviceObject field before calling
+	 * vmbus_child_dev_add()
+	 */
+	newchannel->device_obj = vmbus_device_create(
+		&newchannel->offermsg.offer.if_type,
+		&newchannel->offermsg.offer.if_instance,
+		newchannel);
+	if (!newchannel->device_obj)
+		goto err_deq_chan;
+
+	/*
+	 * Add the new device to the bus. This will kick off device-driver
+	 * binding which eventually invokes the device driver's AddDevice()
+	 * method.
+	 */
+	if (vmbus_device_register(newchannel->device_obj) != 0) {
+		pr_err("unable to add child device object (relid %d)\n",
+			newchannel->offermsg.child_relid);
+		kfree(newchannel->device_obj);
+		goto err_deq_chan;
+	}
+	return;
+
+err_deq_chan:
+	spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
+	list_del(&newchannel->listentry);
+	spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
+
+	if (newchannel->target_cpu != get_cpu()) {
+		put_cpu();
+		smp_call_function_single(newchannel->target_cpu,
+					 percpu_channel_deq, newchannel, true);
+	} else {
+		percpu_channel_deq(newchannel);
+		put_cpu();
+	}
+
+err_free_chan:
+	free_channel(newchannel);
+}
+
+enum {
+	IDE = 0,
+	SCSI,
+	NIC,
+	MAX_PERF_CHN,
+};
+
+/*
+ * This is an array of device_ids (device types) that are performance critical.
+ * We attempt to distribute the interrupt load for these devices across
+ * all available CPUs.
+ */
+static const struct hv_vmbus_device_id hp_devs[] = {
+	/* IDE */
+	{ HV_IDE_GUID, },
+	/* Storage - SCSI */
+	{ HV_SCSI_GUID, },
+	/* Network */
+	{ HV_NIC_GUID, },
+	/* NetworkDirect Guest RDMA */
+	{ HV_ND_GUID, },
+};
+
+
+/*
+ * We use this state to statically distribute the channel interrupt load.
+ */
+static u32  next_vp;
+
+/*
+ * Starting with Win8, we can statically distribute the incoming
+ * channel interrupt load by binding a channel to VCPU. We
+ * implement here a simple round robin scheme for distributing
+ * the interrupt load.
+ * We will bind channels that are not performance critical to cpu 0 and
+ * performance critical channels (IDE, SCSI and Network) will be uniformly
+ * distributed across all available CPUs.
+ */
+static void init_vp_index(struct vmbus_channel *channel, const uuid_le *type_guid)
+{
+	u32 cur_cpu;
+	int i;
+	bool perf_chn = false;
+	u32 max_cpus = num_online_cpus();
+
+	for (i = IDE; i < MAX_PERF_CHN; i++) {
+		if (!memcmp(type_guid->b, hp_devs[i].guid,
+				 sizeof(uuid_le))) {
+			perf_chn = true;
+			break;
+		}
+	}
+	if ((vmbus_proto_version == VERSION_WS2008) ||
+	    (vmbus_proto_version == VERSION_WIN7) || (!perf_chn)) {
+		/*
+		 * Prior to win8, all channel interrupts are
+		 * delivered on cpu 0.
+		 * Also if the channel is not a performance critical
+		 * channel, bind it to cpu 0.
+		 */
+		channel->target_cpu = 0;
+		channel->target_vp = 0;
+		return;
+	}
+	cur_cpu = (++next_vp % max_cpus);
+	channel->target_cpu = cur_cpu;
+	channel->target_vp = hv_context.vp_index[cur_cpu];
+}
+
+/*
+ * vmbus_onoffer - Handler for channel offers from vmbus in parent partition.
+ *
+ */
+static void vmbus_onoffer(struct vmbus_channel_message_header *hdr)
+{
+	struct vmbus_channel_offer_channel *offer;
+	struct vmbus_channel *newchannel;
+
+	offer = (struct vmbus_channel_offer_channel *)hdr;
+
+	/* Allocate the channel object and save this offer. */
+	newchannel = alloc_channel();
+	if (!newchannel) {
+		pr_err("Unable to allocate channel object\n");
+		return;
+	}
+
+	/*
+	 * By default we setup state to enable batched
+	 * reading. A specific service can choose to
+	 * disable this prior to opening the channel.
+	 */
+	newchannel->batched_reading = true;
+
+	/*
+	 * Setup state for signalling the host.
+	 */
+	newchannel->sig_event = (struct hv_input_signal_event *)
+				(ALIGN((unsigned long)
+				&newchannel->sig_buf,
+				HV_HYPERCALL_PARAM_ALIGN));
+
+	newchannel->sig_event->connectionid.asu32 = 0;
+	newchannel->sig_event->connectionid.u.id = VMBUS_EVENT_CONNECTION_ID;
+	newchannel->sig_event->flag_number = 0;
+	newchannel->sig_event->rsvdz = 0;
+
+	if (vmbus_proto_version != VERSION_WS2008) {
+		newchannel->is_dedicated_interrupt =
+				(offer->is_dedicated_interrupt != 0);
+		newchannel->sig_event->connectionid.u.id =
+				offer->connection_id;
+	}
+
+	init_vp_index(newchannel, &offer->offer.if_type);
+
+	memcpy(&newchannel->offermsg, offer,
+	       sizeof(struct vmbus_channel_offer_channel));
+	newchannel->monitor_grp = (u8)offer->monitorid / 32;
+	newchannel->monitor_bit = (u8)offer->monitorid % 32;
+
+	vmbus_process_offer(newchannel);
+}
+
+/*
+ * vmbus_onoffer_rescind - Rescind offer handler.
+ *
+ * We queue a work item to process this offer synchronously
+ */
+static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr)
+{
+	struct vmbus_channel_rescind_offer *rescind;
+	struct vmbus_channel *channel;
+	unsigned long flags;
+	struct device *dev;
+
+	rescind = (struct vmbus_channel_rescind_offer *)hdr;
+	channel = relid2channel(rescind->child_relid);
+
+	if (channel == NULL) {
+		hv_process_channel_removal(NULL, rescind->child_relid);
+		return;
+	}
+
+	spin_lock_irqsave(&channel->lock, flags);
+	channel->rescind = true;
+	spin_unlock_irqrestore(&channel->lock, flags);
+
+	if (channel->device_obj) {
+		/*
+		 * We will have to unregister this device from the
+		 * driver core.
+		 */
+		dev = get_device(&channel->device_obj->device);
+		if (dev) {
+			vmbus_device_unregister(channel->device_obj);
+			put_device(dev);
+		}
+	} else {
+		hv_process_channel_removal(channel,
+			channel->offermsg.child_relid);
+	}
+}
+
+/*
+ * vmbus_onoffers_delivered -
+ * This is invoked when all offers have been delivered.
+ *
+ * Nothing to do here.
+ */
+static void vmbus_onoffers_delivered(
+			struct vmbus_channel_message_header *hdr)
+{
+}
+
+/*
+ * vmbus_onopen_result - Open result handler.
+ *
+ * This is invoked when we received a response to our channel open request.
+ * Find the matching request, copy the response and signal the requesting
+ * thread.
+ */
+static void vmbus_onopen_result(struct vmbus_channel_message_header *hdr)
+{
+	struct vmbus_channel_open_result *result;
+	struct vmbus_channel_msginfo *msginfo;
+	struct vmbus_channel_message_header *requestheader;
+	struct vmbus_channel_open_channel *openmsg;
+	unsigned long flags;
+
+	result = (struct vmbus_channel_open_result *)hdr;
+
+	/*
+	 * Find the open msg, copy the result and signal/unblock the wait event
+	 */
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+
+	list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
+				msglistentry) {
+		requestheader =
+			(struct vmbus_channel_message_header *)msginfo->msg;
+
+		if (requestheader->msgtype == CHANNELMSG_OPENCHANNEL) {
+			openmsg =
+			(struct vmbus_channel_open_channel *)msginfo->msg;
+			if (openmsg->child_relid == result->child_relid &&
+			    openmsg->openid == result->openid) {
+				memcpy(&msginfo->response.open_result,
+				       result,
+				       sizeof(
+					struct vmbus_channel_open_result));
+				complete(&msginfo->waitevent);
+				break;
+			}
+		}
+	}
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+}
+
+/*
+ * vmbus_ongpadl_created - GPADL created handler.
+ *
+ * This is invoked when we received a response to our gpadl create request.
+ * Find the matching request, copy the response and signal the requesting
+ * thread.
+ */
+static void vmbus_ongpadl_created(struct vmbus_channel_message_header *hdr)
+{
+	struct vmbus_channel_gpadl_created *gpadlcreated;
+	struct vmbus_channel_msginfo *msginfo;
+	struct vmbus_channel_message_header *requestheader;
+	struct vmbus_channel_gpadl_header *gpadlheader;
+	unsigned long flags;
+
+	gpadlcreated = (struct vmbus_channel_gpadl_created *)hdr;
+
+	/*
+	 * Find the establish msg, copy the result and signal/unblock the wait
+	 * event
+	 */
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+
+	list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
+				msglistentry) {
+		requestheader =
+			(struct vmbus_channel_message_header *)msginfo->msg;
+
+		if (requestheader->msgtype == CHANNELMSG_GPADL_HEADER) {
+			gpadlheader =
+			(struct vmbus_channel_gpadl_header *)requestheader;
+
+			if ((gpadlcreated->child_relid ==
+			     gpadlheader->child_relid) &&
+			    (gpadlcreated->gpadl == gpadlheader->gpadl)) {
+				memcpy(&msginfo->response.gpadl_created,
+				       gpadlcreated,
+				       sizeof(
+					struct vmbus_channel_gpadl_created));
+				complete(&msginfo->waitevent);
+				break;
+			}
+		}
+	}
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+}
+
+/*
+ * vmbus_ongpadl_torndown - GPADL torndown handler.
+ *
+ * This is invoked when we received a response to our gpadl teardown request.
+ * Find the matching request, copy the response and signal the requesting
+ * thread.
+ */
+static void vmbus_ongpadl_torndown(
+			struct vmbus_channel_message_header *hdr)
+{
+	struct vmbus_channel_gpadl_torndown *gpadl_torndown;
+	struct vmbus_channel_msginfo *msginfo;
+	struct vmbus_channel_message_header *requestheader;
+	struct vmbus_channel_gpadl_teardown *gpadl_teardown;
+	unsigned long flags;
+
+	gpadl_torndown = (struct vmbus_channel_gpadl_torndown *)hdr;
+
+	/*
+	 * Find the open msg, copy the result and signal/unblock the wait event
+	 */
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+
+	list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
+				msglistentry) {
+		requestheader =
+			(struct vmbus_channel_message_header *)msginfo->msg;
+
+		if (requestheader->msgtype == CHANNELMSG_GPADL_TEARDOWN) {
+			gpadl_teardown =
+			(struct vmbus_channel_gpadl_teardown *)requestheader;
+
+			if (gpadl_torndown->gpadl == gpadl_teardown->gpadl) {
+				memcpy(&msginfo->response.gpadl_torndown,
+				       gpadl_torndown,
+				       sizeof(
+					struct vmbus_channel_gpadl_torndown));
+				complete(&msginfo->waitevent);
+				break;
+			}
+		}
+	}
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+}
+
+/*
+ * vmbus_onversion_response - Version response handler
+ *
+ * This is invoked when we received a response to our initiate contact request.
+ * Find the matching request, copy the response and signal the requesting
+ * thread.
+ */
+static void vmbus_onversion_response(
+		struct vmbus_channel_message_header *hdr)
+{
+	struct vmbus_channel_msginfo *msginfo;
+	struct vmbus_channel_message_header *requestheader;
+	struct vmbus_channel_version_response *version_response;
+	unsigned long flags;
+
+	version_response = (struct vmbus_channel_version_response *)hdr;
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+
+	list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
+				msglistentry) {
+		requestheader =
+			(struct vmbus_channel_message_header *)msginfo->msg;
+
+		if (requestheader->msgtype ==
+		    CHANNELMSG_INITIATE_CONTACT) {
+			memcpy(&msginfo->response.version_response,
+			      version_response,
+			      sizeof(struct vmbus_channel_version_response));
+			complete(&msginfo->waitevent);
+		}
+	}
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+}
+
+/* Channel message dispatch table */
+struct vmbus_channel_message_table_entry
+	channel_message_table[CHANNELMSG_COUNT] = {
+	{CHANNELMSG_INVALID,			0, NULL},
+	{CHANNELMSG_OFFERCHANNEL,		0, vmbus_onoffer},
+	{CHANNELMSG_RESCIND_CHANNELOFFER,	0, vmbus_onoffer_rescind},
+	{CHANNELMSG_REQUESTOFFERS,		0, NULL},
+	{CHANNELMSG_ALLOFFERS_DELIVERED,	1, vmbus_onoffers_delivered},
+	{CHANNELMSG_OPENCHANNEL,		0, NULL},
+	{CHANNELMSG_OPENCHANNEL_RESULT,		1, vmbus_onopen_result},
+	{CHANNELMSG_CLOSECHANNEL,		0, NULL},
+	{CHANNELMSG_GPADL_HEADER,		0, NULL},
+	{CHANNELMSG_GPADL_BODY,			0, NULL},
+	{CHANNELMSG_GPADL_CREATED,		1, vmbus_ongpadl_created},
+	{CHANNELMSG_GPADL_TEARDOWN,		0, NULL},
+	{CHANNELMSG_GPADL_TORNDOWN,		1, vmbus_ongpadl_torndown},
+	{CHANNELMSG_RELID_RELEASED,		0, NULL},
+	{CHANNELMSG_INITIATE_CONTACT,		0, NULL},
+	{CHANNELMSG_VERSION_RESPONSE,		1, vmbus_onversion_response},
+	{CHANNELMSG_UNLOAD,			0, NULL},
+};
+
+/*
+ * vmbus_onmessage - Handler for channel protocol messages.
+ *
+ * This is invoked in the vmbus worker thread context.
+ */
+void vmbus_onmessage(void *context)
+{
+	struct hv_message *msg = context;
+	struct vmbus_channel_message_header *hdr;
+	int size;
+
+	hdr = (struct vmbus_channel_message_header *)msg->u.payload;
+	size = msg->header.payload_size;
+
+	if (hdr->msgtype >= CHANNELMSG_COUNT) {
+		pr_err("Received invalid channel message type %d size %d\n",
+			   hdr->msgtype, size);
+		print_hex_dump_bytes("", DUMP_PREFIX_NONE,
+				     (unsigned char *)msg->u.payload, size);
+		return;
+	}
+
+	if (channel_message_table[hdr->msgtype].message_handler)
+		channel_message_table[hdr->msgtype].message_handler(hdr);
+	else
+		pr_err("Unhandled channel message type %d\n", hdr->msgtype);
+}
+
+/*
+ * vmbus_request_offers - Send a request to get all our pending offers.
+ */
+int vmbus_request_offers(void)
+{
+	struct vmbus_channel_message_header *msg;
+	struct vmbus_channel_msginfo *msginfo;
+	int ret;
+
+	msginfo = kmalloc(sizeof(*msginfo) +
+			  sizeof(struct vmbus_channel_message_header),
+			  GFP_KERNEL);
+	if (!msginfo)
+		return -ENOMEM;
+
+	msg = (struct vmbus_channel_message_header *)msginfo->msg;
+
+	msg->msgtype = CHANNELMSG_REQUESTOFFERS;
+
+
+	ret = vmbus_post_msg(msg,
+			       sizeof(struct vmbus_channel_message_header));
+	if (ret != 0) {
+		pr_err("Unable to request offers - %d\n", ret);
+
+		goto cleanup;
+	}
+
+cleanup:
+	kfree(msginfo);
+
+	return ret;
+}
+
+/*
+ * Retrieve the (sub) channel on which to send an outgoing request.
+ * When a primary channel has multiple sub-channels, we try to
+ * distribute the load equally amongst all available channels.
+ */
+struct vmbus_channel *vmbus_get_outgoing_channel(struct vmbus_channel *primary)
+{
+	struct list_head *cur, *tmp;
+	int cur_cpu;
+	struct vmbus_channel *cur_channel;
+	struct vmbus_channel *outgoing_channel = primary;
+	int next_channel;
+	int i = 1;
+
+	if (list_empty(&primary->sc_list))
+		return outgoing_channel;
+
+	next_channel = primary->next_oc++;
+
+	if (next_channel > (primary->num_sc)) {
+		primary->next_oc = 0;
+		return outgoing_channel;
+	}
+
+	cur_cpu = hv_context.vp_index[get_cpu()];
+	put_cpu();
+	list_for_each_safe(cur, tmp, &primary->sc_list) {
+		cur_channel = list_entry(cur, struct vmbus_channel, sc_list);
+		if (cur_channel->state != CHANNEL_OPENED_STATE)
+			continue;
+
+		if (cur_channel->target_vp == cur_cpu)
+			return cur_channel;
+
+		if (i == next_channel)
+			return cur_channel;
+
+		i++;
+	}
+
+	return outgoing_channel;
+}
+EXPORT_SYMBOL_GPL(vmbus_get_outgoing_channel);
+
+static void invoke_sc_cb(struct vmbus_channel *primary_channel)
+{
+	struct list_head *cur, *tmp;
+	struct vmbus_channel *cur_channel;
+
+	if (primary_channel->sc_creation_callback == NULL)
+		return;
+
+	list_for_each_safe(cur, tmp, &primary_channel->sc_list) {
+		cur_channel = list_entry(cur, struct vmbus_channel, sc_list);
+
+		primary_channel->sc_creation_callback(cur_channel);
+	}
+}
+
+void vmbus_set_sc_create_callback(struct vmbus_channel *primary_channel,
+				void (*sc_cr_cb)(struct vmbus_channel *new_sc))
+{
+	primary_channel->sc_creation_callback = sc_cr_cb;
+}
+EXPORT_SYMBOL_GPL(vmbus_set_sc_create_callback);
+
+bool vmbus_are_subchannels_present(struct vmbus_channel *primary)
+{
+	bool ret;
+
+	ret = !list_empty(&primary->sc_list);
+
+	if (ret) {
+		/*
+		 * Invoke the callback on sub-channel creation.
+		 * This will present a uniform interface to the
+		 * clients.
+		 */
+		invoke_sc_cb(primary);
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(vmbus_are_subchannels_present);
diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
new file mode 100644
index 000000000..b27220a42
--- /dev/null
+++ b/drivers/hv/connection.c
@@ -0,0 +1,480 @@
+/*
+ *
+ * Copyright (c) 2009, Microsoft Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
+ * Place - Suite 330, Boston, MA 02111-1307 USA.
+ *
+ * Authors:
+ *   Haiyang Zhang <haiyangz@microsoft.com>
+ *   Hank Janssen  <hjanssen@microsoft.com>
+ *
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/wait.h>
+#include <linux/delay.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/hyperv.h>
+#include <linux/export.h>
+#include <asm/hyperv.h>
+#include "hyperv_vmbus.h"
+
+
+struct vmbus_connection vmbus_connection = {
+	.conn_state		= DISCONNECTED,
+	.next_gpadl_handle	= ATOMIC_INIT(0xE1E10),
+};
+
+/*
+ * Negotiated protocol version with the host.
+ */
+__u32 vmbus_proto_version;
+EXPORT_SYMBOL_GPL(vmbus_proto_version);
+
+static __u32 vmbus_get_next_version(__u32 current_version)
+{
+	switch (current_version) {
+	case (VERSION_WIN7):
+		return VERSION_WS2008;
+
+	case (VERSION_WIN8):
+		return VERSION_WIN7;
+
+	case (VERSION_WIN8_1):
+		return VERSION_WIN8;
+
+	case (VERSION_WS2008):
+	default:
+		return VERSION_INVAL;
+	}
+}
+
+static int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo,
+					__u32 version)
+{
+	int ret = 0;
+	struct vmbus_channel_initiate_contact *msg;
+	unsigned long flags;
+
+	init_completion(&msginfo->waitevent);
+
+	msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;
+
+	msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
+	msg->vmbus_version_requested = version;
+	msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
+	msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]);
+	msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]);
+	if (version == VERSION_WIN8_1) {
+		msg->target_vcpu = hv_context.vp_index[get_cpu()];
+		put_cpu();
+	}
+
+	/*
+	 * Add to list before we send the request since we may
+	 * receive the response before returning from this routine
+	 */
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+	list_add_tail(&msginfo->msglistentry,
+		      &vmbus_connection.chn_msg_list);
+
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+
+	ret = vmbus_post_msg(msg,
+			       sizeof(struct vmbus_channel_initiate_contact));
+	if (ret != 0) {
+		spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+		list_del(&msginfo->msglistentry);
+		spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
+					flags);
+		return ret;
+	}
+
+	/* Wait for the connection response */
+	wait_for_completion(&msginfo->waitevent);
+
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+	list_del(&msginfo->msglistentry);
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+
+	/* Check if successful */
+	if (msginfo->response.version_response.version_supported) {
+		vmbus_connection.conn_state = CONNECTED;
+	} else {
+		return -ECONNREFUSED;
+	}
+
+	return ret;
+}
+
+/*
+ * vmbus_connect - Sends a connect request on the partition service connection
+ */
+int vmbus_connect(void)
+{
+	int ret = 0;
+	struct vmbus_channel_msginfo *msginfo = NULL;
+	__u32 version;
+
+	/* Initialize the vmbus connection */
+	vmbus_connection.conn_state = CONNECTING;
+	vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
+	if (!vmbus_connection.work_queue) {
+		ret = -ENOMEM;
+		goto cleanup;
+	}
+
+	INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
+	spin_lock_init(&vmbus_connection.channelmsg_lock);
+
+	INIT_LIST_HEAD(&vmbus_connection.chn_list);
+	spin_lock_init(&vmbus_connection.channel_lock);
+
+	/*
+	 * Setup the vmbus event connection for channel interrupt
+	 * abstraction stuff
+	 */
+	vmbus_connection.int_page =
+	(void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, 0);
+	if (vmbus_connection.int_page == NULL) {
+		ret = -ENOMEM;
+		goto cleanup;
+	}
+
+	vmbus_connection.recv_int_page = vmbus_connection.int_page;
+	vmbus_connection.send_int_page =
+		(void *)((unsigned long)vmbus_connection.int_page +
+			(PAGE_SIZE >> 1));
+
+	/*
+	 * Setup the monitor notification facility. The 1st page for
+	 * parent->child and the 2nd page for child->parent
+	 */
+	vmbus_connection.monitor_pages[0] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
+	vmbus_connection.monitor_pages[1] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
+	if ((vmbus_connection.monitor_pages[0] == NULL) ||
+	    (vmbus_connection.monitor_pages[1] == NULL)) {
+		ret = -ENOMEM;
+		goto cleanup;
+	}
+
+	msginfo = kzalloc(sizeof(*msginfo) +
+			  sizeof(struct vmbus_channel_initiate_contact),
+			  GFP_KERNEL);
+	if (msginfo == NULL) {
+		ret = -ENOMEM;
+		goto cleanup;
+	}
+
+	/*
+	 * Negotiate a compatible VMBUS version number with the
+	 * host. We start with the highest number we can support
+	 * and work our way down until we negotiate a compatible
+	 * version.
+	 */
+
+	version = VERSION_CURRENT;
+
+	do {
+		ret = vmbus_negotiate_version(msginfo, version);
+		if (ret == -ETIMEDOUT)
+			goto cleanup;
+
+		if (vmbus_connection.conn_state == CONNECTED)
+			break;
+
+		version = vmbus_get_next_version(version);
+	} while (version != VERSION_INVAL);
+
+	if (version == VERSION_INVAL)
+		goto cleanup;
+
+	vmbus_proto_version = version;
+	pr_info("Hyper-V Host Build:%d-%d.%d-%d-%d.%d; Vmbus version:%d.%d\n",
+		    host_info_eax, host_info_ebx >> 16,
+		    host_info_ebx & 0xFFFF, host_info_ecx,
+		    host_info_edx >> 24, host_info_edx & 0xFFFFFF,
+		    version >> 16, version & 0xFFFF);
+
+	kfree(msginfo);
+	return 0;
+
+cleanup:
+	pr_err("Unable to connect to host\n");
+
+	vmbus_connection.conn_state = DISCONNECTED;
+	vmbus_disconnect();
+
+	kfree(msginfo);
+
+	return ret;
+}
+
+void vmbus_disconnect(void)
+{
+	if (vmbus_connection.work_queue) {
+		drain_workqueue(vmbus_connection.work_queue);
+		destroy_workqueue(vmbus_connection.work_queue);
+	}
+
+	if (vmbus_connection.int_page) {
+		free_pages((unsigned long)vmbus_connection.int_page, 0);
+		vmbus_connection.int_page = NULL;
+	}
+
+	free_pages((unsigned long)vmbus_connection.monitor_pages[0], 0);
+	free_pages((unsigned long)vmbus_connection.monitor_pages[1], 0);
+	vmbus_connection.monitor_pages[0] = NULL;
+	vmbus_connection.monitor_pages[1] = NULL;
+}
+
+/*
+ * Map the given relid to the corresponding channel based on the
+ * per-cpu list of channels that have been affinitized to this CPU.
+ * This will be used in the channel callback path as we can do this
+ * mapping in a lock-free fashion.
+ */
+static struct vmbus_channel *pcpu_relid2channel(u32 relid)
+{
+	struct vmbus_channel *channel;
+	struct vmbus_channel *found_channel  = NULL;
+	int cpu = smp_processor_id();
+	struct list_head *pcpu_head = &hv_context.percpu_list[cpu];
+
+	list_for_each_entry(channel, pcpu_head, percpu_list) {
+		if (channel->offermsg.child_relid == relid) {
+			found_channel = channel;
+			break;
+		}
+	}
+
+	return found_channel;
+}
+
+/*
+ * relid2channel - Get the channel object given its
+ * child relative id (ie channel id)
+ */
+struct vmbus_channel *relid2channel(u32 relid)
+{
+	struct vmbus_channel *channel;
+	struct vmbus_channel *found_channel  = NULL;
+	unsigned long flags;
+	struct list_head *cur, *tmp;
+	struct vmbus_channel *cur_sc;
+
+	spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
+	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
+		if (channel->offermsg.child_relid == relid) {
+			found_channel = channel;
+			break;
+		} else if (!list_empty(&channel->sc_list)) {
+			/*
+			 * Deal with sub-channels.
+			 */
+			list_for_each_safe(cur, tmp, &channel->sc_list) {
+				cur_sc = list_entry(cur, struct vmbus_channel,
+							sc_list);
+				if (cur_sc->offermsg.child_relid == relid) {
+					found_channel = cur_sc;
+					break;
+				}
+			}
+		}
+	}
+	spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
+
+	return found_channel;
+}
+
+/*
+ * process_chn_event - Process a channel event notification
+ */
+static void process_chn_event(u32 relid)
+{
+	struct vmbus_channel *channel;
+	void *arg;
+	bool read_state;
+	u32 bytes_to_read;
+
+	/*
+	 * Find the channel based on this relid and invokes the
+	 * channel callback to process the event
+	 */
+	channel = pcpu_relid2channel(relid);
+
+	if (!channel)
+		return;
+
+	/*
+	 * A channel once created is persistent even when there
+	 * is no driver handling the device. An unloading driver
+	 * sets the onchannel_callback to NULL on the same CPU
+	 * as where this interrupt is handled (in an interrupt context).
+	 * Thus, checking and invoking the driver specific callback takes
+	 * care of orderly unloading of the driver.
+	 */
+
+	if (channel->onchannel_callback != NULL) {
+		arg = channel->channel_callback_context;
+		read_state = channel->batched_reading;
+		/*
+		 * This callback reads the messages sent by the host.
+		 * We can optimize host to guest signaling by ensuring:
+		 * 1. While reading the channel, we disable interrupts from
+		 *    host.
+		 * 2. Ensure that we process all posted messages from the host
+		 *    before returning from this callback.
+		 * 3. Once we return, enable signaling from the host. Once this
+		 *    state is set we check to see if additional packets are
+		 *    available to read. In this case we repeat the process.
+		 */
+
+		do {
+			if (read_state)
+				hv_begin_read(&channel->inbound);
+			channel->onchannel_callback(arg);
+			if (read_state)
+				bytes_to_read = hv_end_read(&channel->inbound);
+			else
+				bytes_to_read = 0;
+		} while (read_state && (bytes_to_read != 0));
+	}
+}
+
+/*
+ * vmbus_on_event - Handler for events
+ */
+void vmbus_on_event(unsigned long data)
+{
+	u32 dword;
+	u32 maxdword;
+	int bit;
+	u32 relid;
+	u32 *recv_int_page = NULL;
+	void *page_addr;
+	int cpu = smp_processor_id();
+	union hv_synic_event_flags *event;
+
+	if ((vmbus_proto_version == VERSION_WS2008) ||
+		(vmbus_proto_version == VERSION_WIN7)) {
+		maxdword = MAX_NUM_CHANNELS_SUPPORTED >> 5;
+		recv_int_page = vmbus_connection.recv_int_page;
+	} else {
+		/*
+		 * When the host is win8 and beyond, the event page
+		 * can be directly checked to get the id of the channel
+		 * that has the interrupt pending.
+		 */
+		maxdword = HV_EVENT_FLAGS_DWORD_COUNT;
+		page_addr = hv_context.synic_event_page[cpu];
+		event = (union hv_synic_event_flags *)page_addr +
+						 VMBUS_MESSAGE_SINT;
+		recv_int_page = event->flags32;
+	}
+
+
+
+	/* Check events */
+	if (!recv_int_page)
+		return;
+	for (dword = 0; dword < maxdword; dword++) {
+		if (!recv_int_page[dword])
+			continue;
+		for (bit = 0; bit < 32; bit++) {
+			if (sync_test_and_clear_bit(bit,
+				(unsigned long *)&recv_int_page[dword])) {
+				relid = (dword << 5) + bit;
+
+				if (relid == 0)
+					/*
+					 * Special case - vmbus
+					 * channel protocol msg
+					 */
+					continue;
+
+				process_chn_event(relid);
+			}
+		}
+	}
+}
+
+/*
+ * vmbus_post_msg - Send a msg on the vmbus's message connection
+ */
+int vmbus_post_msg(void *buffer, size_t buflen)
+{
+	union hv_connection_id conn_id;
+	int ret = 0;
+	int retries = 0;
+	u32 msec = 1;
+
+	conn_id.asu32 = 0;
+	conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
+
+	/*
+	 * hv_post_message() can have transient failures because of
+	 * insufficient resources. Retry the operation a couple of
+	 * times before giving up.
+	 */
+	while (retries < 20) {
+		ret = hv_post_message(conn_id, 1, buffer, buflen);
+
+		switch (ret) {
+		case HV_STATUS_INVALID_CONNECTION_ID:
+			/*
+			 * We could get this if we send messages too
+			 * frequently.
+			 */
+			ret = -EAGAIN;
+			break;
+		case HV_STATUS_INSUFFICIENT_MEMORY:
+		case HV_STATUS_INSUFFICIENT_BUFFERS:
+			ret = -ENOMEM;
+			break;
+		case HV_STATUS_SUCCESS:
+			return ret;
+		default:
+			pr_err("hv_post_msg() failed; error code:%d\n", ret);
+			return -EINVAL;
+		}
+
+		retries++;
+		msleep(msec);
+		if (msec < 2048)
+			msec *= 2;
+	}
+	return ret;
+}
+
+/*
+ * vmbus_set_event - Send an event notification to the parent
+ */
+int vmbus_set_event(struct vmbus_channel *channel)
+{
+	u32 child_relid = channel->offermsg.child_relid;
+
+	if (!channel->is_dedicated_interrupt) {
+		/* Each u32 represents 32 channels */
+		sync_set_bit(child_relid & 31,
+			(unsigned long *)vmbus_connection.send_int_page +
+			(child_relid >> 5));
+	}
+
+	return hv_signal_event(channel->sig_event);
+}
diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
new file mode 100644
index 000000000..d3943bcee
--- /dev/null
+++ b/drivers/hv/hv.c
@@ -0,0 +1,535 @@
+/*
+ * Copyright (c) 2009, Microsoft Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
+ * Place - Suite 330, Boston, MA 02111-1307 USA.
+ *
+ * Authors:
+ *   Haiyang Zhang <haiyangz@microsoft.com>
+ *   Hank Janssen  <hjanssen@microsoft.com>
+ *
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/hyperv.h>
+#include <linux/version.h>
+#include <linux/interrupt.h>
+#include <linux/clockchips.h>
+#include <asm/hyperv.h>
+#include <asm/mshyperv.h>
+#include "hyperv_vmbus.h"
+
+/* The one and only */
+struct hv_context hv_context = {
+	.synic_initialized	= false,
+	.hypercall_page		= NULL,
+};
+
+#define HV_TIMER_FREQUENCY (10 * 1000 * 1000) /* 100ns period */
+#define HV_MAX_MAX_DELTA_TICKS 0xffffffff
+#define HV_MIN_DELTA_TICKS 1
+
+/*
+ * query_hypervisor_info - Get version info of the windows hypervisor
+ */
+unsigned int host_info_eax;
+unsigned int host_info_ebx;
+unsigned int host_info_ecx;
+unsigned int host_info_edx;
+
+static int query_hypervisor_info(void)
+{
+	unsigned int eax;
+	unsigned int ebx;
+	unsigned int ecx;
+	unsigned int edx;
+	unsigned int max_leaf;
+	unsigned int op;
+
+	/*
+	* Its assumed that this is called after confirming that Viridian
+	* is present. Query id and revision.
+	*/
+	eax = 0;
+	ebx = 0;
+	ecx = 0;
+	edx = 0;
+	op = HVCPUID_VENDOR_MAXFUNCTION;
+	cpuid(op, &eax, &ebx, &ecx, &edx);
+
+	max_leaf = eax;
+
+	if (max_leaf >= HVCPUID_VERSION) {
+		eax = 0;
+		ebx = 0;
+		ecx = 0;
+		edx = 0;
+		op = HVCPUID_VERSION;
+		cpuid(op, &eax, &ebx, &ecx, &edx);
+		host_info_eax = eax;
+		host_info_ebx = ebx;
+		host_info_ecx = ecx;
+		host_info_edx = edx;
+	}
+	return max_leaf;
+}
+
+/*
+ * do_hypercall- Invoke the specified hypercall
+ */
+static u64 do_hypercall(u64 control, void *input, void *output)
+{
+#ifdef CONFIG_X86_64
+	u64 hv_status = 0;
+	u64 input_address = (input) ? virt_to_phys(input) : 0;
+	u64 output_address = (output) ? virt_to_phys(output) : 0;
+	void *hypercall_page = hv_context.hypercall_page;
+
+	__asm__ __volatile__("mov %0, %%r8" : : "r" (output_address) : "r8");
+	__asm__ __volatile__("call *%3" : "=a" (hv_status) :
+			     "c" (control), "d" (input_address),
+			     "m" (hypercall_page));
+
+	return hv_status;
+
+#else
+
+	u32 control_hi = control >> 32;
+	u32 control_lo = control & 0xFFFFFFFF;
+	u32 hv_status_hi = 1;
+	u32 hv_status_lo = 1;
+	u64 input_address = (input) ? virt_to_phys(input) : 0;
+	u32 input_address_hi = input_address >> 32;
+	u32 input_address_lo = input_address & 0xFFFFFFFF;
+	u64 output_address = (output) ? virt_to_phys(output) : 0;
+	u32 output_address_hi = output_address >> 32;
+	u32 output_address_lo = output_address & 0xFFFFFFFF;
+	void *hypercall_page = hv_context.hypercall_page;
+
+	__asm__ __volatile__ ("call *%8" : "=d"(hv_status_hi),
+			      "=a"(hv_status_lo) : "d" (control_hi),
+			      "a" (control_lo), "b" (input_address_hi),
+			      "c" (input_address_lo), "D"(output_address_hi),
+			      "S"(output_address_lo), "m" (hypercall_page));
+
+	return hv_status_lo | ((u64)hv_status_hi << 32);
+#endif /* !x86_64 */
+}
+
+/*
+ * hv_init - Main initialization routine.
+ *
+ * This routine must be called before any other routines in here are called
+ */
+int hv_init(void)
+{
+	int max_leaf;
+	union hv_x64_msr_hypercall_contents hypercall_msr;
+	void *virtaddr = NULL;
+
+	memset(hv_context.synic_event_page, 0, sizeof(void *) * NR_CPUS);
+	memset(hv_context.synic_message_page, 0,
+	       sizeof(void *) * NR_CPUS);
+	memset(hv_context.post_msg_page, 0,
+	       sizeof(void *) * NR_CPUS);
+	memset(hv_context.vp_index, 0,
+	       sizeof(int) * NR_CPUS);
+	memset(hv_context.event_dpc, 0,
+	       sizeof(void *) * NR_CPUS);
+	memset(hv_context.clk_evt, 0,
+	       sizeof(void *) * NR_CPUS);
+
+	max_leaf = query_hypervisor_info();
+
+	/*
+	 * Write our OS ID.
+	 */
+	hv_context.guestid = generate_guest_id(0, LINUX_VERSION_CODE, 0);
+	wrmsrl(HV_X64_MSR_GUEST_OS_ID, hv_context.guestid);
+
+	/* See if the hypercall page is already set */
+	rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
+
+	virtaddr = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL_EXEC);
+
+	if (!virtaddr)
+		goto cleanup;
+
+	hypercall_msr.enable = 1;
+
+	hypercall_msr.guest_physical_address = vmalloc_to_pfn(virtaddr);
+	wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
+
+	/* Confirm that hypercall page did get setup. */
+	hypercall_msr.as_uint64 = 0;
+	rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
+
+	if (!hypercall_msr.enable)
+		goto cleanup;
+
+	hv_context.hypercall_page = virtaddr;
+
+	return 0;
+
+cleanup:
+	if (virtaddr) {
+		if (hypercall_msr.enable) {
+			hypercall_msr.as_uint64 = 0;
+			wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
+		}
+
+		vfree(virtaddr);
+	}
+
+	return -ENOTSUPP;
+}
+
+/*
+ * hv_cleanup - Cleanup routine.
+ *
+ * This routine is called normally during driver unloading or exiting.
+ */
+void hv_cleanup(void)
+{
+	union hv_x64_msr_hypercall_contents hypercall_msr;
+
+	/* Reset our OS id */
+	wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
+
+	if (hv_context.hypercall_page) {
+		hypercall_msr.as_uint64 = 0;
+		wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
+		vfree(hv_context.hypercall_page);
+		hv_context.hypercall_page = NULL;
+	}
+}
+
+/*
+ * hv_post_message - Post a message using the hypervisor message IPC.
+ *
+ * This involves a hypercall.
+ */
+int hv_post_message(union hv_connection_id connection_id,
+		  enum hv_message_type message_type,
+		  void *payload, size_t payload_size)
+{
+
+	struct hv_input_post_message *aligned_msg;
+	u16 status;
+
+	if (payload_size > HV_MESSAGE_PAYLOAD_BYTE_COUNT)
+		return -EMSGSIZE;
+
+	aligned_msg = (struct hv_input_post_message *)
+			hv_context.post_msg_page[get_cpu()];
+
+	aligned_msg->connectionid = connection_id;
+	aligned_msg->reserved = 0;
+	aligned_msg->message_type = message_type;
+	aligned_msg->payload_size = payload_size;
+	memcpy((void *)aligned_msg->payload, payload, payload_size);
+
+	status = do_hypercall(HVCALL_POST_MESSAGE, aligned_msg, NULL)
+		& 0xFFFF;
+
+	put_cpu();
+	return status;
+}
+
+
+/*
+ * hv_signal_event -
+ * Signal an event on the specified connection using the hypervisor event IPC.
+ *
+ * This involves a hypercall.
+ */
+u16 hv_signal_event(void *con_id)
+{
+	u16 status;
+
+	status = (do_hypercall(HVCALL_SIGNAL_EVENT, con_id, NULL) & 0xFFFF);
+
+	return status;
+}
+
+static int hv_ce_set_next_event(unsigned long delta,
+				struct clock_event_device *evt)
+{
+	cycle_t current_tick;
+
+	WARN_ON(evt->mode != CLOCK_EVT_MODE_ONESHOT);
+
+	rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
+	current_tick += delta;
+	wrmsrl(HV_X64_MSR_STIMER0_COUNT, current_tick);
+	return 0;
+}
+
+static void hv_ce_setmode(enum clock_event_mode mode,
+			  struct clock_event_device *evt)
+{
+	union hv_timer_config timer_cfg;
+
+	switch (mode) {
+	case CLOCK_EVT_MODE_PERIODIC:
+		/* unsupported */
+		break;
+
+	case CLOCK_EVT_MODE_ONESHOT:
+		timer_cfg.enable = 1;
+		timer_cfg.auto_enable = 1;
+		timer_cfg.sintx = VMBUS_MESSAGE_SINT;
+		wrmsrl(HV_X64_MSR_STIMER0_CONFIG, timer_cfg.as_uint64);
+		break;
+
+	case CLOCK_EVT_MODE_UNUSED:
+	case CLOCK_EVT_MODE_SHUTDOWN:
+		wrmsrl(HV_X64_MSR_STIMER0_COUNT, 0);
+		wrmsrl(HV_X64_MSR_STIMER0_CONFIG, 0);
+		break;
+	case CLOCK_EVT_MODE_RESUME:
+		break;
+	}
+}
+
+static void hv_init_clockevent_device(struct clock_event_device *dev, int cpu)
+{
+	dev->name = "Hyper-V clockevent";
+	dev->features = CLOCK_EVT_FEAT_ONESHOT;
+	dev->cpumask = cpumask_of(cpu);
+	dev->rating = 1000;
+	/*
+	 * Avoid settint dev->owner = THIS_MODULE deliberately as doing so will
+	 * result in clockevents_config_and_register() taking additional
+	 * references to the hv_vmbus module making it impossible to unload.
+	 */
+
+	dev->set_mode = hv_ce_setmode;
+	dev->set_next_event = hv_ce_set_next_event;
+}
+
+
+int hv_synic_alloc(void)
+{
+	size_t size = sizeof(struct tasklet_struct);
+	size_t ced_size = sizeof(struct clock_event_device);
+	int cpu;
+
+	for_each_online_cpu(cpu) {
+		hv_context.event_dpc[cpu] = kmalloc(size, GFP_ATOMIC);
+		if (hv_context.event_dpc[cpu] == NULL) {
+			pr_err("Unable to allocate event dpc\n");
+			goto err;
+		}
+		tasklet_init(hv_context.event_dpc[cpu], vmbus_on_event, cpu);
+
+		hv_context.clk_evt[cpu] = kzalloc(ced_size, GFP_ATOMIC);
+		if (hv_context.clk_evt[cpu] == NULL) {
+			pr_err("Unable to allocate clock event device\n");
+			goto err;
+		}
+		hv_init_clockevent_device(hv_context.clk_evt[cpu], cpu);
+
+		hv_context.synic_message_page[cpu] =
+			(void *)get_zeroed_page(GFP_ATOMIC);
+
+		if (hv_context.synic_message_page[cpu] == NULL) {
+			pr_err("Unable to allocate SYNIC message page\n");
+			goto err;
+		}
+
+		hv_context.synic_event_page[cpu] =
+			(void *)get_zeroed_page(GFP_ATOMIC);
+
+		if (hv_context.synic_event_page[cpu] == NULL) {
+			pr_err("Unable to allocate SYNIC event page\n");
+			goto err;
+		}
+
+		hv_context.post_msg_page[cpu] =
+			(void *)get_zeroed_page(GFP_ATOMIC);
+
+		if (hv_context.post_msg_page[cpu] == NULL) {
+			pr_err("Unable to allocate post msg page\n");
+			goto err;
+		}
+	}
+
+	return 0;
+err:
+	return -ENOMEM;
+}
+
+static void hv_synic_free_cpu(int cpu)
+{
+	kfree(hv_context.event_dpc[cpu]);
+	kfree(hv_context.clk_evt[cpu]);
+	if (hv_context.synic_event_page[cpu])
+		free_page((unsigned long)hv_context.synic_event_page[cpu]);
+	if (hv_context.synic_message_page[cpu])
+		free_page((unsigned long)hv_context.synic_message_page[cpu]);
+	if (hv_context.post_msg_page[cpu])
+		free_page((unsigned long)hv_context.post_msg_page[cpu]);
+}
+
+void hv_synic_free(void)
+{
+	int cpu;
+
+	for_each_online_cpu(cpu)
+		hv_synic_free_cpu(cpu);
+}
+
+/*
+ * hv_synic_init - Initialize the Synthethic Interrupt Controller.
+ *
+ * If it is already initialized by another entity (ie x2v shim), we need to
+ * retrieve the initialized message and event pages.  Otherwise, we create and
+ * initialize the message and event pages.
+ */
+void hv_synic_init(void *arg)
+{
+	u64 version;
+	union hv_synic_simp simp;
+	union hv_synic_siefp siefp;
+	union hv_synic_sint shared_sint;
+	union hv_synic_scontrol sctrl;
+	u64 vp_index;
+
+	int cpu = smp_processor_id();
+
+	if (!hv_context.hypercall_page)
+		return;
+
+	/* Check the version */
+	rdmsrl(HV_X64_MSR_SVERSION, version);
+
+	/* Setup the Synic's message page */
+	rdmsrl(HV_X64_MSR_SIMP, simp.as_uint64);
+	simp.simp_enabled = 1;
+	simp.base_simp_gpa = virt_to_phys(hv_context.synic_message_page[cpu])
+		>> PAGE_SHIFT;
+
+	wrmsrl(HV_X64_MSR_SIMP, simp.as_uint64);
+
+	/* Setup the Synic's event page */
+	rdmsrl(HV_X64_MSR_SIEFP, siefp.as_uint64);
+	siefp.siefp_enabled = 1;
+	siefp.base_siefp_gpa = virt_to_phys(hv_context.synic_event_page[cpu])
+		>> PAGE_SHIFT;
+
+	wrmsrl(HV_X64_MSR_SIEFP, siefp.as_uint64);
+
+	/* Setup the shared SINT. */
+	rdmsrl(HV_X64_MSR_SINT0 + VMBUS_MESSAGE_SINT, shared_sint.as_uint64);
+
+	shared_sint.as_uint64 = 0;
+	shared_sint.vector = HYPERVISOR_CALLBACK_VECTOR;
+	shared_sint.masked = false;
+	shared_sint.auto_eoi = true;
+
+	wrmsrl(HV_X64_MSR_SINT0 + VMBUS_MESSAGE_SINT, shared_sint.as_uint64);
+
+	/* Enable the global synic bit */
+	rdmsrl(HV_X64_MSR_SCONTROL, sctrl.as_uint64);
+	sctrl.enable = 1;
+
+	wrmsrl(HV_X64_MSR_SCONTROL, sctrl.as_uint64);
+
+	hv_context.synic_initialized = true;
+
+	/*
+	 * Setup the mapping between Hyper-V's notion
+	 * of cpuid and Linux' notion of cpuid.
+	 * This array will be indexed using Linux cpuid.
+	 */
+	rdmsrl(HV_X64_MSR_VP_INDEX, vp_index);
+	hv_context.vp_index[cpu] = (u32)vp_index;
+
+	INIT_LIST_HEAD(&hv_context.percpu_list[cpu]);
+
+	/*
+	 * Register the per-cpu clockevent source.
+	 */
+	if (ms_hyperv.features & HV_X64_MSR_SYNTIMER_AVAILABLE)
+		clockevents_config_and_register(hv_context.clk_evt[cpu],
+						HV_TIMER_FREQUENCY,
+						HV_MIN_DELTA_TICKS,
+						HV_MAX_MAX_DELTA_TICKS);
+	return;
+}
+
+/*
+ * hv_synic_clockevents_cleanup - Cleanup clockevent devices
+ */
+void hv_synic_clockevents_cleanup(void)
+{
+	int cpu;
+
+	if (!(ms_hyperv.features & HV_X64_MSR_SYNTIMER_AVAILABLE))
+		return;
+
+	for_each_online_cpu(cpu)
+		clockevents_unbind_device(hv_context.clk_evt[cpu], cpu);
+}
+
+/*
+ * hv_synic_cleanup - Cleanup routine for hv_synic_init().
+ */
+void hv_synic_cleanup(void *arg)
+{
+	union hv_synic_sint shared_sint;
+	union hv_synic_simp simp;
+	union hv_synic_siefp siefp;
+	union hv_synic_scontrol sctrl;
+	int cpu = smp_processor_id();
+
+	if (!hv_context.synic_initialized)
+		return;
+
+	/* Turn off clockevent device */
+	if (ms_hyperv.features & HV_X64_MSR_SYNTIMER_AVAILABLE)
+		hv_ce_setmode(CLOCK_EVT_MODE_SHUTDOWN,
+			      hv_context.clk_evt[cpu]);
+
+	rdmsrl(HV_X64_MSR_SINT0 + VMBUS_MESSAGE_SINT, shared_sint.as_uint64);
+
+	shared_sint.masked = 1;
+
+	/* Need to correctly cleanup in the case of SMP!!! */
+	/* Disable the interrupt */
+	wrmsrl(HV_X64_MSR_SINT0 + VMBUS_MESSAGE_SINT, shared_sint.as_uint64);
+
+	rdmsrl(HV_X64_MSR_SIMP, simp.as_uint64);
+	simp.simp_enabled = 0;
+	simp.base_simp_gpa = 0;
+
+	wrmsrl(HV_X64_MSR_SIMP, simp.as_uint64);
+
+	rdmsrl(HV_X64_MSR_SIEFP, siefp.as_uint64);
+	siefp.siefp_enabled = 0;
+	siefp.base_siefp_gpa = 0;
+
+	wrmsrl(HV_X64_MSR_SIEFP, siefp.as_uint64);
+
+	/* Disable the global synic bit */
+	rdmsrl(HV_X64_MSR_SCONTROL, sctrl.as_uint64);
+	sctrl.enable = 0;
+	wrmsrl(HV_X64_MSR_SCONTROL, sctrl.as_uint64);
+
+	hv_synic_free_cpu(cpu);
+}
diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
new file mode 100644
index 000000000..cb5b7dc97
--- /dev/null
+++ b/drivers/hv/hv_balloon.c
@@ -0,0 +1,1616 @@
+/*
+ * Copyright (c) 2012, Microsoft Corporation.
+ *
+ * Author:
+ *   K. Y. Srinivasan <kys@microsoft.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ * NON INFRINGEMENT.  See the GNU General Public License for more
+ * details.
+ *
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/jiffies.h>
+#include <linux/mman.h>
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/kthread.h>
+#include <linux/completion.h>
+#include <linux/memory_hotplug.h>
+#include <linux/memory.h>
+#include <linux/notifier.h>
+#include <linux/percpu_counter.h>
+
+#include <linux/hyperv.h>
+
+/*
+ * We begin with definitions supporting the Dynamic Memory protocol
+ * with the host.
+ *
+ * Begin protocol definitions.
+ */
+
+
+
+/*
+ * Protocol versions. The low word is the minor version, the high word the major
+ * version.
+ *
+ * History:
+ * Initial version 1.0
+ * Changed to 0.1 on 2009/03/25
+ * Changes to 0.2 on 2009/05/14
+ * Changes to 0.3 on 2009/12/03
+ * Changed to 1.0 on 2011/04/05
+ */
+
+#define DYNMEM_MAKE_VERSION(Major, Minor) ((__u32)(((Major) << 16) | (Minor)))
+#define DYNMEM_MAJOR_VERSION(Version) ((__u32)(Version) >> 16)
+#define DYNMEM_MINOR_VERSION(Version) ((__u32)(Version) & 0xff)
+
+enum {
+	DYNMEM_PROTOCOL_VERSION_1 = DYNMEM_MAKE_VERSION(0, 3),
+	DYNMEM_PROTOCOL_VERSION_2 = DYNMEM_MAKE_VERSION(1, 0),
+
+	DYNMEM_PROTOCOL_VERSION_WIN7 = DYNMEM_PROTOCOL_VERSION_1,
+	DYNMEM_PROTOCOL_VERSION_WIN8 = DYNMEM_PROTOCOL_VERSION_2,
+
+	DYNMEM_PROTOCOL_VERSION_CURRENT = DYNMEM_PROTOCOL_VERSION_WIN8
+};
+
+
+
+/*
+ * Message Types
+ */
+
+enum dm_message_type {
+	/*
+	 * Version 0.3
+	 */
+	DM_ERROR			= 0,
+	DM_VERSION_REQUEST		= 1,
+	DM_VERSION_RESPONSE		= 2,
+	DM_CAPABILITIES_REPORT		= 3,
+	DM_CAPABILITIES_RESPONSE	= 4,
+	DM_STATUS_REPORT		= 5,
+	DM_BALLOON_REQUEST		= 6,
+	DM_BALLOON_RESPONSE		= 7,
+	DM_UNBALLOON_REQUEST		= 8,
+	DM_UNBALLOON_RESPONSE		= 9,
+	DM_MEM_HOT_ADD_REQUEST		= 10,
+	DM_MEM_HOT_ADD_RESPONSE		= 11,
+	DM_VERSION_03_MAX		= 11,
+	/*
+	 * Version 1.0.
+	 */
+	DM_INFO_MESSAGE			= 12,
+	DM_VERSION_1_MAX		= 12
+};
+
+
+/*
+ * Structures defining the dynamic memory management
+ * protocol.
+ */
+
+union dm_version {
+	struct {
+		__u16 minor_version;
+		__u16 major_version;
+	};
+	__u32 version;
+} __packed;
+
+
+union dm_caps {
+	struct {
+		__u64 balloon:1;
+		__u64 hot_add:1;
+		/*
+		 * To support guests that may have alignment
+		 * limitations on hot-add, the guest can specify
+		 * its alignment requirements; a value of n
+		 * represents an alignment of 2^n in mega bytes.
+		 */
+		__u64 hot_add_alignment:4;
+		__u64 reservedz:58;
+	} cap_bits;
+	__u64 caps;
+} __packed;
+
+union dm_mem_page_range {
+	struct  {
+		/*
+		 * The PFN number of the first page in the range.
+		 * 40 bits is the architectural limit of a PFN
+		 * number for AMD64.
+		 */
+		__u64 start_page:40;
+		/*
+		 * The number of pages in the range.
+		 */
+		__u64 page_cnt:24;
+	} finfo;
+	__u64  page_range;
+} __packed;
+
+
+
+/*
+ * The header for all dynamic memory messages:
+ *
+ * type: Type of the message.
+ * size: Size of the message in bytes; including the header.
+ * trans_id: The guest is responsible for manufacturing this ID.
+ */
+
+struct dm_header {
+	__u16 type;
+	__u16 size;
+	__u32 trans_id;
+} __packed;
+
+/*
+ * A generic message format for dynamic memory.
+ * Specific message formats are defined later in the file.
+ */
+
+struct dm_message {
+	struct dm_header hdr;
+	__u8 data[]; /* enclosed message */
+} __packed;
+
+
+/*
+ * Specific message types supporting the dynamic memory protocol.
+ */
+
+/*
+ * Version negotiation message. Sent from the guest to the host.
+ * The guest is free to try different versions until the host
+ * accepts the version.
+ *
+ * dm_version: The protocol version requested.
+ * is_last_attempt: If TRUE, this is the last version guest will request.
+ * reservedz: Reserved field, set to zero.
+ */
+
+struct dm_version_request {
+	struct dm_header hdr;
+	union dm_version version;
+	__u32 is_last_attempt:1;
+	__u32 reservedz:31;
+} __packed;
+
+/*
+ * Version response message; Host to Guest and indicates
+ * if the host has accepted the version sent by the guest.
+ *
+ * is_accepted: If TRUE, host has accepted the version and the guest
+ * should proceed to the next stage of the protocol. FALSE indicates that
+ * guest should re-try with a different version.
+ *
+ * reservedz: Reserved field, set to zero.
+ */
+
+struct dm_version_response {
+	struct dm_header hdr;
+	__u64 is_accepted:1;
+	__u64 reservedz:63;
+} __packed;
+
+/*
+ * Message reporting capabilities. This is sent from the guest to the
+ * host.
+ */
+
+struct dm_capabilities {
+	struct dm_header hdr;
+	union dm_caps caps;
+	__u64 min_page_cnt;
+	__u64 max_page_number;
+} __packed;
+
+/*
+ * Response to the capabilities message. This is sent from the host to the
+ * guest. This message notifies if the host has accepted the guest's
+ * capabilities. If the host has not accepted, the guest must shutdown
+ * the service.
+ *
+ * is_accepted: Indicates if the host has accepted guest's capabilities.
+ * reservedz: Must be 0.
+ */
+
+struct dm_capabilities_resp_msg {
+	struct dm_header hdr;
+	__u64 is_accepted:1;
+	__u64 reservedz:63;
+} __packed;
+
+/*
+ * This message is used to report memory pressure from the guest.
+ * This message is not part of any transaction and there is no
+ * response to this message.
+ *
+ * num_avail: Available memory in pages.
+ * num_committed: Committed memory in pages.
+ * page_file_size: The accumulated size of all page files
+ *		   in the system in pages.
+ * zero_free: The nunber of zero and free pages.
+ * page_file_writes: The writes to the page file in pages.
+ * io_diff: An indicator of file cache efficiency or page file activity,
+ *	    calculated as File Cache Page Fault Count - Page Read Count.
+ *	    This value is in pages.
+ *
+ * Some of these metrics are Windows specific and fortunately
+ * the algorithm on the host side that computes the guest memory
+ * pressure only uses num_committed value.
+ */
+
+struct dm_status {
+	struct dm_header hdr;
+	__u64 num_avail;
+	__u64 num_committed;
+	__u64 page_file_size;
+	__u64 zero_free;
+	__u32 page_file_writes;
+	__u32 io_diff;
+} __packed;
+
+
+/*
+ * Message to ask the guest to allocate memory - balloon up message.
+ * This message is sent from the host to the guest. The guest may not be
+ * able to allocate as much memory as requested.
+ *
+ * num_pages: number of pages to allocate.
+ */
+
+struct dm_balloon {
+	struct dm_header hdr;
+	__u32 num_pages;
+	__u32 reservedz;
+} __packed;
+
+
+/*
+ * Balloon response message; this message is sent from the guest
+ * to the host in response to the balloon message.
+ *
+ * reservedz: Reserved; must be set to zero.
+ * more_pages: If FALSE, this is the last message of the transaction.
+ * if TRUE there will atleast one more message from the guest.
+ *
+ * range_count: The number of ranges in the range array.
+ *
+ * range_array: An array of page ranges returned to the host.
+ *
+ */
+
+struct dm_balloon_response {
+	struct dm_header hdr;
+	__u32 reservedz;
+	__u32 more_pages:1;
+	__u32 range_count:31;
+	union dm_mem_page_range range_array[];
+} __packed;
+
+/*
+ * Un-balloon message; this message is sent from the host
+ * to the guest to give guest more memory.
+ *
+ * more_pages: If FALSE, this is the last message of the transaction.
+ * if TRUE there will atleast one more message from the guest.
+ *
+ * reservedz: Reserved; must be set to zero.
+ *
+ * range_count: The number of ranges in the range array.
+ *
+ * range_array: An array of page ranges returned to the host.
+ *
+ */
+
+struct dm_unballoon_request {
+	struct dm_header hdr;
+	__u32 more_pages:1;
+	__u32 reservedz:31;
+	__u32 range_count;
+	union dm_mem_page_range range_array[];
+} __packed;
+
+/*
+ * Un-balloon response message; this message is sent from the guest
+ * to the host in response to an unballoon request.
+ *
+ */
+
+struct dm_unballoon_response {
+	struct dm_header hdr;
+} __packed;
+
+
+/*
+ * Hot add request message. Message sent from the host to the guest.
+ *
+ * mem_range: Memory range to hot add.
+ *
+ * On Linux we currently don't support this since we cannot hot add
+ * arbitrary granularity of memory.
+ */
+
+struct dm_hot_add {
+	struct dm_header hdr;
+	union dm_mem_page_range range;
+} __packed;
+
+/*
+ * Hot add response message.
+ * This message is sent by the guest to report the status of a hot add request.
+ * If page_count is less than the requested page count, then the host should
+ * assume all further hot add requests will fail, since this indicates that
+ * the guest has hit an upper physical memory barrier.
+ *
+ * Hot adds may also fail due to low resources; in this case, the guest must
+ * not complete this message until the hot add can succeed, and the host must
+ * not send a new hot add request until the response is sent.
+ * If VSC fails to hot add memory DYNMEM_NUMBER_OF_UNSUCCESSFUL_HOTADD_ATTEMPTS
+ * times it fails the request.
+ *
+ *
+ * page_count: number of pages that were successfully hot added.
+ *
+ * result: result of the operation 1: success, 0: failure.
+ *
+ */
+
+struct dm_hot_add_response {
+	struct dm_header hdr;
+	__u32 page_count;
+	__u32 result;
+} __packed;
+
+/*
+ * Types of information sent from host to the guest.
+ */
+
+enum dm_info_type {
+	INFO_TYPE_MAX_PAGE_CNT = 0,
+	MAX_INFO_TYPE
+};
+
+
+/*
+ * Header for the information message.
+ */
+
+struct dm_info_header {
+	enum dm_info_type type;
+	__u32 data_size;
+} __packed;
+
+/*
+ * This message is sent from the host to the guest to pass
+ * some relevant information (win8 addition).
+ *
+ * reserved: no used.
+ * info_size: size of the information blob.
+ * info: information blob.
+ */
+
+struct dm_info_msg {
+	struct dm_header hdr;
+	__u32 reserved;
+	__u32 info_size;
+	__u8  info[];
+};
+
+/*
+ * End protocol definitions.
+ */
+
+/*
+ * State to manage hot adding memory into the guest.
+ * The range start_pfn : end_pfn specifies the range
+ * that the host has asked us to hot add. The range
+ * start_pfn : ha_end_pfn specifies the range that we have
+ * currently hot added. We hot add in multiples of 128M
+ * chunks; it is possible that we may not be able to bring
+ * online all the pages in the region. The range
+ * covered_end_pfn defines the pages that can
+ * be brough online.
+ */
+
+struct hv_hotadd_state {
+	struct list_head list;
+	unsigned long start_pfn;
+	unsigned long covered_end_pfn;
+	unsigned long ha_end_pfn;
+	unsigned long end_pfn;
+};
+
+struct balloon_state {
+	__u32 num_pages;
+	struct work_struct wrk;
+};
+
+struct hot_add_wrk {
+	union dm_mem_page_range ha_page_range;
+	union dm_mem_page_range ha_region_range;
+	struct work_struct wrk;
+};
+
+static bool hot_add = true;
+static bool do_hot_add;
+/*
+ * Delay reporting memory pressure by
+ * the specified number of seconds.
+ */
+static uint pressure_report_delay = 45;
+
+/*
+ * The last time we posted a pressure report to host.
+ */
+static unsigned long last_post_time;
+
+module_param(hot_add, bool, (S_IRUGO | S_IWUSR));
+MODULE_PARM_DESC(hot_add, "If set attempt memory hot_add");
+
+module_param(pressure_report_delay, uint, (S_IRUGO | S_IWUSR));
+MODULE_PARM_DESC(pressure_report_delay, "Delay in secs in reporting pressure");
+static atomic_t trans_id = ATOMIC_INIT(0);
+
+static int dm_ring_size = (5 * PAGE_SIZE);
+
+/*
+ * Driver specific state.
+ */
+
+enum hv_dm_state {
+	DM_INITIALIZING = 0,
+	DM_INITIALIZED,
+	DM_BALLOON_UP,
+	DM_BALLOON_DOWN,
+	DM_HOT_ADD,
+	DM_INIT_ERROR
+};
+
+
+static __u8 recv_buffer[PAGE_SIZE];
+static __u8 *send_buffer;
+#define PAGES_IN_2M	512
+#define HA_CHUNK (32 * 1024)
+
+struct hv_dynmem_device {
+	struct hv_device *dev;
+	enum hv_dm_state state;
+	struct completion host_event;
+	struct completion config_event;
+
+	/*
+	 * Number of pages we have currently ballooned out.
+	 */
+	unsigned int num_pages_ballooned;
+	unsigned int num_pages_onlined;
+	unsigned int num_pages_added;
+
+	/*
+	 * State to manage the ballooning (up) operation.
+	 */
+	struct balloon_state balloon_wrk;
+
+	/*
+	 * State to execute the "hot-add" operation.
+	 */
+	struct hot_add_wrk ha_wrk;
+
+	/*
+	 * This state tracks if the host has specified a hot-add
+	 * region.
+	 */
+	bool host_specified_ha_region;
+
+	/*
+	 * State to synchronize hot-add.
+	 */
+	struct completion  ol_waitevent;
+	bool ha_waiting;
+	/*
+	 * This thread handles hot-add
+	 * requests from the host as well as notifying
+	 * the host with regards to memory pressure in
+	 * the guest.
+	 */
+	struct task_struct *thread;
+
+	struct mutex ha_region_mutex;
+
+	/*
+	 * A list of hot-add regions.
+	 */
+	struct list_head ha_region_list;
+
+	/*
+	 * We start with the highest version we can support
+	 * and downgrade based on the host; we save here the
+	 * next version to try.
+	 */
+	__u32 next_version;
+};
+
+static struct hv_dynmem_device dm_device;
+
+static void post_status(struct hv_dynmem_device *dm);
+
+#ifdef CONFIG_MEMORY_HOTPLUG
+static int hv_memory_notifier(struct notifier_block *nb, unsigned long val,
+			      void *v)
+{
+	struct memory_notify *mem = (struct memory_notify *)v;
+
+	switch (val) {
+	case MEM_GOING_ONLINE:
+		mutex_lock(&dm_device.ha_region_mutex);
+		break;
+
+	case MEM_ONLINE:
+		dm_device.num_pages_onlined += mem->nr_pages;
+	case MEM_CANCEL_ONLINE:
+		mutex_unlock(&dm_device.ha_region_mutex);
+		if (dm_device.ha_waiting) {
+			dm_device.ha_waiting = false;
+			complete(&dm_device.ol_waitevent);
+		}
+		break;
+
+	case MEM_OFFLINE:
+		mutex_lock(&dm_device.ha_region_mutex);
+		dm_device.num_pages_onlined -= mem->nr_pages;
+		mutex_unlock(&dm_device.ha_region_mutex);
+		break;
+	case MEM_GOING_OFFLINE:
+	case MEM_CANCEL_OFFLINE:
+		break;
+	}
+	return NOTIFY_OK;
+}
+
+static struct notifier_block hv_memory_nb = {
+	.notifier_call = hv_memory_notifier,
+	.priority = 0
+};
+
+
+static void hv_bring_pgs_online(unsigned long start_pfn, unsigned long size)
+{
+	int i;
+
+	for (i = 0; i < size; i++) {
+		struct page *pg;
+		pg = pfn_to_page(start_pfn + i);
+		__online_page_set_limits(pg);
+		__online_page_increment_counters(pg);
+		__online_page_free(pg);
+	}
+}
+
+static void hv_mem_hot_add(unsigned long start, unsigned long size,
+				unsigned long pfn_count,
+				struct hv_hotadd_state *has)
+{
+	int ret = 0;
+	int i, nid;
+	unsigned long start_pfn;
+	unsigned long processed_pfn;
+	unsigned long total_pfn = pfn_count;
+
+	for (i = 0; i < (size/HA_CHUNK); i++) {
+		start_pfn = start + (i * HA_CHUNK);
+		has->ha_end_pfn +=  HA_CHUNK;
+
+		if (total_pfn > HA_CHUNK) {
+			processed_pfn = HA_CHUNK;
+			total_pfn -= HA_CHUNK;
+		} else {
+			processed_pfn = total_pfn;
+			total_pfn = 0;
+		}
+
+		has->covered_end_pfn +=  processed_pfn;
+
+		init_completion(&dm_device.ol_waitevent);
+		dm_device.ha_waiting = true;
+
+		mutex_unlock(&dm_device.ha_region_mutex);
+		nid = memory_add_physaddr_to_nid(PFN_PHYS(start_pfn));
+		ret = add_memory(nid, PFN_PHYS((start_pfn)),
+				(HA_CHUNK << PAGE_SHIFT));
+
+		if (ret) {
+			pr_info("hot_add memory failed error is %d\n", ret);
+			if (ret == -EEXIST) {
+				/*
+				 * This error indicates that the error
+				 * is not a transient failure. This is the
+				 * case where the guest's physical address map
+				 * precludes hot adding memory. Stop all further
+				 * memory hot-add.
+				 */
+				do_hot_add = false;
+			}
+			has->ha_end_pfn -= HA_CHUNK;
+			has->covered_end_pfn -=  processed_pfn;
+			mutex_lock(&dm_device.ha_region_mutex);
+			break;
+		}
+
+		/*
+		 * Wait for the memory block to be onlined.
+		 * Since the hot add has succeeded, it is ok to
+		 * proceed even if the pages in the hot added region
+		 * have not been "onlined" within the allowed time.
+		 */
+		wait_for_completion_timeout(&dm_device.ol_waitevent, 5*HZ);
+		mutex_lock(&dm_device.ha_region_mutex);
+		post_status(&dm_device);
+	}
+
+	return;
+}
+
+static void hv_online_page(struct page *pg)
+{
+	struct list_head *cur;
+	struct hv_hotadd_state *has;
+	unsigned long cur_start_pgp;
+	unsigned long cur_end_pgp;
+
+	list_for_each(cur, &dm_device.ha_region_list) {
+		has = list_entry(cur, struct hv_hotadd_state, list);
+		cur_start_pgp = (unsigned long)pfn_to_page(has->start_pfn);
+		cur_end_pgp = (unsigned long)pfn_to_page(has->covered_end_pfn);
+
+		if (((unsigned long)pg >= cur_start_pgp) &&
+			((unsigned long)pg < cur_end_pgp)) {
+			/*
+			 * This frame is currently backed; online the
+			 * page.
+			 */
+			__online_page_set_limits(pg);
+			__online_page_increment_counters(pg);
+			__online_page_free(pg);
+		}
+	}
+}
+
+static bool pfn_covered(unsigned long start_pfn, unsigned long pfn_cnt)
+{
+	struct list_head *cur;
+	struct hv_hotadd_state *has;
+	unsigned long residual, new_inc;
+
+	if (list_empty(&dm_device.ha_region_list))
+		return false;
+
+	list_for_each(cur, &dm_device.ha_region_list) {
+		has = list_entry(cur, struct hv_hotadd_state, list);
+
+		/*
+		 * If the pfn range we are dealing with is not in the current
+		 * "hot add block", move on.
+		 */
+		if ((start_pfn >= has->end_pfn))
+			continue;
+		/*
+		 * If the current hot add-request extends beyond
+		 * our current limit; extend it.
+		 */
+		if ((start_pfn + pfn_cnt) > has->end_pfn) {
+			residual = (start_pfn + pfn_cnt - has->end_pfn);
+			/*
+			 * Extend the region by multiples of HA_CHUNK.
+			 */
+			new_inc = (residual / HA_CHUNK) * HA_CHUNK;
+			if (residual % HA_CHUNK)
+				new_inc += HA_CHUNK;
+
+			has->end_pfn += new_inc;
+		}
+
+		/*
+		 * If the current start pfn is not where the covered_end
+		 * is, update it.
+		 */
+
+		if (has->covered_end_pfn != start_pfn)
+			has->covered_end_pfn = start_pfn;
+
+		return true;
+
+	}
+
+	return false;
+}
+
+static unsigned long handle_pg_range(unsigned long pg_start,
+					unsigned long pg_count)
+{
+	unsigned long start_pfn = pg_start;
+	unsigned long pfn_cnt = pg_count;
+	unsigned long size;
+	struct list_head *cur;
+	struct hv_hotadd_state *has;
+	unsigned long pgs_ol = 0;
+	unsigned long old_covered_state;
+
+	if (list_empty(&dm_device.ha_region_list))
+		return 0;
+
+	list_for_each(cur, &dm_device.ha_region_list) {
+		has = list_entry(cur, struct hv_hotadd_state, list);
+
+		/*
+		 * If the pfn range we are dealing with is not in the current
+		 * "hot add block", move on.
+		 */
+		if ((start_pfn >= has->end_pfn))
+			continue;
+
+		old_covered_state = has->covered_end_pfn;
+
+		if (start_pfn < has->ha_end_pfn) {
+			/*
+			 * This is the case where we are backing pages
+			 * in an already hot added region. Bring
+			 * these pages online first.
+			 */
+			pgs_ol = has->ha_end_pfn - start_pfn;
+			if (pgs_ol > pfn_cnt)
+				pgs_ol = pfn_cnt;
+
+			/*
+			 * Check if the corresponding memory block is already
+			 * online by checking its last previously backed page.
+			 * In case it is we need to bring rest (which was not
+			 * backed previously) online too.
+			 */
+			if (start_pfn > has->start_pfn &&
+			    !PageReserved(pfn_to_page(start_pfn - 1)))
+				hv_bring_pgs_online(start_pfn, pgs_ol);
+
+			has->covered_end_pfn +=  pgs_ol;
+			pfn_cnt -= pgs_ol;
+		}
+
+		if ((has->ha_end_pfn < has->end_pfn) && (pfn_cnt > 0)) {
+			/*
+			 * We have some residual hot add range
+			 * that needs to be hot added; hot add
+			 * it now. Hot add a multiple of
+			 * of HA_CHUNK that fully covers the pages
+			 * we have.
+			 */
+			size = (has->end_pfn - has->ha_end_pfn);
+			if (pfn_cnt <= size) {
+				size = ((pfn_cnt / HA_CHUNK) * HA_CHUNK);
+				if (pfn_cnt % HA_CHUNK)
+					size += HA_CHUNK;
+			} else {
+				pfn_cnt = size;
+			}
+			hv_mem_hot_add(has->ha_end_pfn, size, pfn_cnt, has);
+		}
+		/*
+		 * If we managed to online any pages that were given to us,
+		 * we declare success.
+		 */
+		return has->covered_end_pfn - old_covered_state;
+
+	}
+
+	return 0;
+}
+
+static unsigned long process_hot_add(unsigned long pg_start,
+					unsigned long pfn_cnt,
+					unsigned long rg_start,
+					unsigned long rg_size)
+{
+	struct hv_hotadd_state *ha_region = NULL;
+
+	if (pfn_cnt == 0)
+		return 0;
+
+	if (!dm_device.host_specified_ha_region)
+		if (pfn_covered(pg_start, pfn_cnt))
+			goto do_pg_range;
+
+	/*
+	 * If the host has specified a hot-add range; deal with it first.
+	 */
+
+	if (rg_size != 0) {
+		ha_region = kzalloc(sizeof(struct hv_hotadd_state), GFP_KERNEL);
+		if (!ha_region)
+			return 0;
+
+		INIT_LIST_HEAD(&ha_region->list);
+
+		list_add_tail(&ha_region->list, &dm_device.ha_region_list);
+		ha_region->start_pfn = rg_start;
+		ha_region->ha_end_pfn = rg_start;
+		ha_region->covered_end_pfn = pg_start;
+		ha_region->end_pfn = rg_start + rg_size;
+	}
+
+do_pg_range:
+	/*
+	 * Process the page range specified; bringing them
+	 * online if possible.
+	 */
+	return handle_pg_range(pg_start, pfn_cnt);
+}
+
+#endif
+
+static void hot_add_req(struct work_struct *dummy)
+{
+	struct dm_hot_add_response resp;
+#ifdef CONFIG_MEMORY_HOTPLUG
+	unsigned long pg_start, pfn_cnt;
+	unsigned long rg_start, rg_sz;
+#endif
+	struct hv_dynmem_device *dm = &dm_device;
+
+	memset(&resp, 0, sizeof(struct dm_hot_add_response));
+	resp.hdr.type = DM_MEM_HOT_ADD_RESPONSE;
+	resp.hdr.size = sizeof(struct dm_hot_add_response);
+
+#ifdef CONFIG_MEMORY_HOTPLUG
+	mutex_lock(&dm_device.ha_region_mutex);
+	pg_start = dm->ha_wrk.ha_page_range.finfo.start_page;
+	pfn_cnt = dm->ha_wrk.ha_page_range.finfo.page_cnt;
+
+	rg_start = dm->ha_wrk.ha_region_range.finfo.start_page;
+	rg_sz = dm->ha_wrk.ha_region_range.finfo.page_cnt;
+
+	if ((rg_start == 0) && (!dm->host_specified_ha_region)) {
+		unsigned long region_size;
+		unsigned long region_start;
+
+		/*
+		 * The host has not specified the hot-add region.
+		 * Based on the hot-add page range being specified,
+		 * compute a hot-add region that can cover the pages
+		 * that need to be hot-added while ensuring the alignment
+		 * and size requirements of Linux as it relates to hot-add.
+		 */
+		region_start = pg_start;
+		region_size = (pfn_cnt / HA_CHUNK) * HA_CHUNK;
+		if (pfn_cnt % HA_CHUNK)
+			region_size += HA_CHUNK;
+
+		region_start = (pg_start / HA_CHUNK) * HA_CHUNK;
+
+		rg_start = region_start;
+		rg_sz = region_size;
+	}
+
+	if (do_hot_add)
+		resp.page_count = process_hot_add(pg_start, pfn_cnt,
+						rg_start, rg_sz);
+
+	dm->num_pages_added += resp.page_count;
+	mutex_unlock(&dm_device.ha_region_mutex);
+#endif
+	/*
+	 * The result field of the response structure has the
+	 * following semantics:
+	 *
+	 * 1. If all or some pages hot-added: Guest should return success.
+	 *
+	 * 2. If no pages could be hot-added:
+	 *
+	 * If the guest returns success, then the host
+	 * will not attempt any further hot-add operations. This
+	 * signifies a permanent failure.
+	 *
+	 * If the guest returns failure, then this failure will be
+	 * treated as a transient failure and the host may retry the
+	 * hot-add operation after some delay.
+	 */
+	if (resp.page_count > 0)
+		resp.result = 1;
+	else if (!do_hot_add)
+		resp.result = 1;
+	else
+		resp.result = 0;
+
+	if (!do_hot_add || (resp.page_count == 0))
+		pr_info("Memory hot add failed\n");
+
+	dm->state = DM_INITIALIZED;
+	resp.hdr.trans_id = atomic_inc_return(&trans_id);
+	vmbus_sendpacket(dm->dev->channel, &resp,
+			sizeof(struct dm_hot_add_response),
+			(unsigned long)NULL,
+			VM_PKT_DATA_INBAND, 0);
+}
+
+static void process_info(struct hv_dynmem_device *dm, struct dm_info_msg *msg)
+{
+	struct dm_info_header *info_hdr;
+
+	info_hdr = (struct dm_info_header *)msg->info;
+
+	switch (info_hdr->type) {
+	case INFO_TYPE_MAX_PAGE_CNT:
+		pr_info("Received INFO_TYPE_MAX_PAGE_CNT\n");
+		pr_info("Data Size is %d\n", info_hdr->data_size);
+		break;
+	default:
+		pr_info("Received Unknown type: %d\n", info_hdr->type);
+	}
+}
+
+static unsigned long compute_balloon_floor(void)
+{
+	unsigned long min_pages;
+#define MB2PAGES(mb) ((mb) << (20 - PAGE_SHIFT))
+	/* Simple continuous piecewiese linear function:
+	 *  max MiB -> min MiB  gradient
+	 *       0         0
+	 *      16        16
+	 *      32        24
+	 *     128        72    (1/2)
+	 *     512       168    (1/4)
+	 *    2048       360    (1/8)
+	 *    8192       744    (1/16)
+	 *   32768      1512	(1/32)
+	 */
+	if (totalram_pages < MB2PAGES(128))
+		min_pages = MB2PAGES(8) + (totalram_pages >> 1);
+	else if (totalram_pages < MB2PAGES(512))
+		min_pages = MB2PAGES(40) + (totalram_pages >> 2);
+	else if (totalram_pages < MB2PAGES(2048))
+		min_pages = MB2PAGES(104) + (totalram_pages >> 3);
+	else if (totalram_pages < MB2PAGES(8192))
+		min_pages = MB2PAGES(232) + (totalram_pages >> 4);
+	else
+		min_pages = MB2PAGES(488) + (totalram_pages >> 5);
+#undef MB2PAGES
+	return min_pages;
+}
+
+/*
+ * Post our status as it relates memory pressure to the
+ * host. Host expects the guests to post this status
+ * periodically at 1 second intervals.
+ *
+ * The metrics specified in this protocol are very Windows
+ * specific and so we cook up numbers here to convey our memory
+ * pressure.
+ */
+
+static void post_status(struct hv_dynmem_device *dm)
+{
+	struct dm_status status;
+	struct sysinfo val;
+	unsigned long now = jiffies;
+	unsigned long last_post = last_post_time;
+
+	if (pressure_report_delay > 0) {
+		--pressure_report_delay;
+		return;
+	}
+
+	if (!time_after(now, (last_post_time + HZ)))
+		return;
+
+	si_meminfo(&val);
+	memset(&status, 0, sizeof(struct dm_status));
+	status.hdr.type = DM_STATUS_REPORT;
+	status.hdr.size = sizeof(struct dm_status);
+	status.hdr.trans_id = atomic_inc_return(&trans_id);
+
+	/*
+	 * The host expects the guest to report free and committed memory.
+	 * Furthermore, the host expects the pressure information to include
+	 * the ballooned out pages. For a given amount of memory that we are
+	 * managing we need to compute a floor below which we should not
+	 * balloon. Compute this and add it to the pressure report.
+	 * We also need to report all offline pages (num_pages_added -
+	 * num_pages_onlined) as committed to the host, otherwise it can try
+	 * asking us to balloon them out.
+	 */
+	status.num_avail = val.freeram;
+	status.num_committed = vm_memory_committed() +
+		dm->num_pages_ballooned +
+		(dm->num_pages_added > dm->num_pages_onlined ?
+		 dm->num_pages_added - dm->num_pages_onlined : 0) +
+		compute_balloon_floor();
+
+	/*
+	 * If our transaction ID is no longer current, just don't
+	 * send the status. This can happen if we were interrupted
+	 * after we picked our transaction ID.
+	 */
+	if (status.hdr.trans_id != atomic_read(&trans_id))
+		return;
+
+	/*
+	 * If the last post time that we sampled has changed,
+	 * we have raced, don't post the status.
+	 */
+	if (last_post != last_post_time)
+		return;
+
+	last_post_time = jiffies;
+	vmbus_sendpacket(dm->dev->channel, &status,
+				sizeof(struct dm_status),
+				(unsigned long)NULL,
+				VM_PKT_DATA_INBAND, 0);
+
+}
+
+static void free_balloon_pages(struct hv_dynmem_device *dm,
+			 union dm_mem_page_range *range_array)
+{
+	int num_pages = range_array->finfo.page_cnt;
+	__u64 start_frame = range_array->finfo.start_page;
+	struct page *pg;
+	int i;
+
+	for (i = 0; i < num_pages; i++) {
+		pg = pfn_to_page(i + start_frame);
+		__free_page(pg);
+		dm->num_pages_ballooned--;
+	}
+}
+
+
+
+static unsigned int alloc_balloon_pages(struct hv_dynmem_device *dm,
+					unsigned int num_pages,
+					struct dm_balloon_response *bl_resp,
+					int alloc_unit)
+{
+	unsigned int i = 0;
+	struct page *pg;
+
+	if (num_pages < alloc_unit)
+		return 0;
+
+	for (i = 0; (i * alloc_unit) < num_pages; i++) {
+		if (bl_resp->hdr.size + sizeof(union dm_mem_page_range) >
+			PAGE_SIZE)
+			return i * alloc_unit;
+
+		/*
+		 * We execute this code in a thread context. Furthermore,
+		 * we don't want the kernel to try too hard.
+		 */
+		pg = alloc_pages(GFP_HIGHUSER | __GFP_NORETRY |
+				__GFP_NOMEMALLOC | __GFP_NOWARN,
+				get_order(alloc_unit << PAGE_SHIFT));
+
+		if (!pg)
+			return i * alloc_unit;
+
+		dm->num_pages_ballooned += alloc_unit;
+
+		/*
+		 * If we allocatted 2M pages; split them so we
+		 * can free them in any order we get.
+		 */
+
+		if (alloc_unit != 1)
+			split_page(pg, get_order(alloc_unit << PAGE_SHIFT));
+
+		bl_resp->range_count++;
+		bl_resp->range_array[i].finfo.start_page =
+			page_to_pfn(pg);
+		bl_resp->range_array[i].finfo.page_cnt = alloc_unit;
+		bl_resp->hdr.size += sizeof(union dm_mem_page_range);
+
+	}
+
+	return num_pages;
+}
+
+
+
+static void balloon_up(struct work_struct *dummy)
+{
+	unsigned int num_pages = dm_device.balloon_wrk.num_pages;
+	unsigned int num_ballooned = 0;
+	struct dm_balloon_response *bl_resp;
+	int alloc_unit;
+	int ret;
+	bool done = false;
+	int i;
+	struct sysinfo val;
+	unsigned long floor;
+
+	/* The host balloons pages in 2M granularity. */
+	WARN_ON_ONCE(num_pages % PAGES_IN_2M != 0);
+
+	/*
+	 * We will attempt 2M allocations. However, if we fail to
+	 * allocate 2M chunks, we will go back to 4k allocations.
+	 */
+	alloc_unit = 512;
+
+	si_meminfo(&val);
+	floor = compute_balloon_floor();
+
+	/* Refuse to balloon below the floor, keep the 2M granularity. */
+	if (val.freeram < num_pages || val.freeram - num_pages < floor) {
+		num_pages = val.freeram > floor ? (val.freeram - floor) : 0;
+		num_pages -= num_pages % PAGES_IN_2M;
+	}
+
+	while (!done) {
+		bl_resp = (struct dm_balloon_response *)send_buffer;
+		memset(send_buffer, 0, PAGE_SIZE);
+		bl_resp->hdr.type = DM_BALLOON_RESPONSE;
+		bl_resp->hdr.size = sizeof(struct dm_balloon_response);
+		bl_resp->more_pages = 1;
+
+
+		num_pages -= num_ballooned;
+		num_ballooned = alloc_balloon_pages(&dm_device, num_pages,
+						    bl_resp, alloc_unit);
+
+		if (alloc_unit != 1 && num_ballooned == 0) {
+			alloc_unit = 1;
+			continue;
+		}
+
+		if (num_ballooned == 0 || num_ballooned == num_pages) {
+			bl_resp->more_pages = 0;
+			done = true;
+			dm_device.state = DM_INITIALIZED;
+		}
+
+		/*
+		 * We are pushing a lot of data through the channel;
+		 * deal with transient failures caused because of the
+		 * lack of space in the ring buffer.
+		 */
+
+		do {
+			bl_resp->hdr.trans_id = atomic_inc_return(&trans_id);
+			ret = vmbus_sendpacket(dm_device.dev->channel,
+						bl_resp,
+						bl_resp->hdr.size,
+						(unsigned long)NULL,
+						VM_PKT_DATA_INBAND, 0);
+
+			if (ret == -EAGAIN)
+				msleep(20);
+			post_status(&dm_device);
+		} while (ret == -EAGAIN);
+
+		if (ret) {
+			/*
+			 * Free up the memory we allocatted.
+			 */
+			pr_info("Balloon response failed\n");
+
+			for (i = 0; i < bl_resp->range_count; i++)
+				free_balloon_pages(&dm_device,
+						 &bl_resp->range_array[i]);
+
+			done = true;
+		}
+	}
+
+}
+
+static void balloon_down(struct hv_dynmem_device *dm,
+			struct dm_unballoon_request *req)
+{
+	union dm_mem_page_range *range_array = req->range_array;
+	int range_count = req->range_count;
+	struct dm_unballoon_response resp;
+	int i;
+
+	for (i = 0; i < range_count; i++) {
+		free_balloon_pages(dm, &range_array[i]);
+		complete(&dm_device.config_event);
+	}
+
+	if (req->more_pages == 1)
+		return;
+
+	memset(&resp, 0, sizeof(struct dm_unballoon_response));
+	resp.hdr.type = DM_UNBALLOON_RESPONSE;
+	resp.hdr.trans_id = atomic_inc_return(&trans_id);
+	resp.hdr.size = sizeof(struct dm_unballoon_response);
+
+	vmbus_sendpacket(dm_device.dev->channel, &resp,
+				sizeof(struct dm_unballoon_response),
+				(unsigned long)NULL,
+				VM_PKT_DATA_INBAND, 0);
+
+	dm->state = DM_INITIALIZED;
+}
+
+static void balloon_onchannelcallback(void *context);
+
+static int dm_thread_func(void *dm_dev)
+{
+	struct hv_dynmem_device *dm = dm_dev;
+
+	while (!kthread_should_stop()) {
+		wait_for_completion_interruptible_timeout(
+						&dm_device.config_event, 1*HZ);
+		/*
+		 * The host expects us to post information on the memory
+		 * pressure every second.
+		 */
+		reinit_completion(&dm_device.config_event);
+		post_status(dm);
+	}
+
+	return 0;
+}
+
+
+static void version_resp(struct hv_dynmem_device *dm,
+			struct dm_version_response *vresp)
+{
+	struct dm_version_request version_req;
+	int ret;
+
+	if (vresp->is_accepted) {
+		/*
+		 * We are done; wakeup the
+		 * context waiting for version
+		 * negotiation.
+		 */
+		complete(&dm->host_event);
+		return;
+	}
+	/*
+	 * If there are more versions to try, continue
+	 * with negotiations; if not
+	 * shutdown the service since we are not able
+	 * to negotiate a suitable version number
+	 * with the host.
+	 */
+	if (dm->next_version == 0)
+		goto version_error;
+
+	dm->next_version = 0;
+	memset(&version_req, 0, sizeof(struct dm_version_request));
+	version_req.hdr.type = DM_VERSION_REQUEST;
+	version_req.hdr.size = sizeof(struct dm_version_request);
+	version_req.hdr.trans_id = atomic_inc_return(&trans_id);
+	version_req.version.version = DYNMEM_PROTOCOL_VERSION_WIN7;
+	version_req.is_last_attempt = 1;
+
+	ret = vmbus_sendpacket(dm->dev->channel, &version_req,
+				sizeof(struct dm_version_request),
+				(unsigned long)NULL,
+				VM_PKT_DATA_INBAND, 0);
+
+	if (ret)
+		goto version_error;
+
+	return;
+
+version_error:
+	dm->state = DM_INIT_ERROR;
+	complete(&dm->host_event);
+}
+
+static void cap_resp(struct hv_dynmem_device *dm,
+			struct dm_capabilities_resp_msg *cap_resp)
+{
+	if (!cap_resp->is_accepted) {
+		pr_info("Capabilities not accepted by host\n");
+		dm->state = DM_INIT_ERROR;
+	}
+	complete(&dm->host_event);
+}
+
+static void balloon_onchannelcallback(void *context)
+{
+	struct hv_device *dev = context;
+	u32 recvlen;
+	u64 requestid;
+	struct dm_message *dm_msg;
+	struct dm_header *dm_hdr;
+	struct hv_dynmem_device *dm = hv_get_drvdata(dev);
+	struct dm_balloon *bal_msg;
+	struct dm_hot_add *ha_msg;
+	union dm_mem_page_range *ha_pg_range;
+	union dm_mem_page_range *ha_region;
+
+	memset(recv_buffer, 0, sizeof(recv_buffer));
+	vmbus_recvpacket(dev->channel, recv_buffer,
+			 PAGE_SIZE, &recvlen, &requestid);
+
+	if (recvlen > 0) {
+		dm_msg = (struct dm_message *)recv_buffer;
+		dm_hdr = &dm_msg->hdr;
+
+		switch (dm_hdr->type) {
+		case DM_VERSION_RESPONSE:
+			version_resp(dm,
+				 (struct dm_version_response *)dm_msg);
+			break;
+
+		case DM_CAPABILITIES_RESPONSE:
+			cap_resp(dm,
+				 (struct dm_capabilities_resp_msg *)dm_msg);
+			break;
+
+		case DM_BALLOON_REQUEST:
+			if (dm->state == DM_BALLOON_UP)
+				pr_warn("Currently ballooning\n");
+			bal_msg = (struct dm_balloon *)recv_buffer;
+			dm->state = DM_BALLOON_UP;
+			dm_device.balloon_wrk.num_pages = bal_msg->num_pages;
+			schedule_work(&dm_device.balloon_wrk.wrk);
+			break;
+
+		case DM_UNBALLOON_REQUEST:
+			dm->state = DM_BALLOON_DOWN;
+			balloon_down(dm,
+				 (struct dm_unballoon_request *)recv_buffer);
+			break;
+
+		case DM_MEM_HOT_ADD_REQUEST:
+			if (dm->state == DM_HOT_ADD)
+				pr_warn("Currently hot-adding\n");
+			dm->state = DM_HOT_ADD;
+			ha_msg = (struct dm_hot_add *)recv_buffer;
+			if (ha_msg->hdr.size == sizeof(struct dm_hot_add)) {
+				/*
+				 * This is a normal hot-add request specifying
+				 * hot-add memory.
+				 */
+				ha_pg_range = &ha_msg->range;
+				dm->ha_wrk.ha_page_range = *ha_pg_range;
+				dm->ha_wrk.ha_region_range.page_range = 0;
+			} else {
+				/*
+				 * Host is specifying that we first hot-add
+				 * a region and then partially populate this
+				 * region.
+				 */
+				dm->host_specified_ha_region = true;
+				ha_pg_range = &ha_msg->range;
+				ha_region = &ha_pg_range[1];
+				dm->ha_wrk.ha_page_range = *ha_pg_range;
+				dm->ha_wrk.ha_region_range = *ha_region;
+			}
+			schedule_work(&dm_device.ha_wrk.wrk);
+			break;
+
+		case DM_INFO_MESSAGE:
+			process_info(dm, (struct dm_info_msg *)dm_msg);
+			break;
+
+		default:
+			pr_err("Unhandled message: type: %d\n", dm_hdr->type);
+
+		}
+	}
+
+}
+
+static int balloon_probe(struct hv_device *dev,
+			const struct hv_vmbus_device_id *dev_id)
+{
+	int ret;
+	unsigned long t;
+	struct dm_version_request version_req;
+	struct dm_capabilities cap_msg;
+
+	do_hot_add = hot_add;
+
+	/*
+	 * First allocate a send buffer.
+	 */
+
+	send_buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!send_buffer)
+		return -ENOMEM;
+
+	ret = vmbus_open(dev->channel, dm_ring_size, dm_ring_size, NULL, 0,
+			balloon_onchannelcallback, dev);
+
+	if (ret)
+		goto probe_error0;
+
+	dm_device.dev = dev;
+	dm_device.state = DM_INITIALIZING;
+	dm_device.next_version = DYNMEM_PROTOCOL_VERSION_WIN7;
+	init_completion(&dm_device.host_event);
+	init_completion(&dm_device.config_event);
+	INIT_LIST_HEAD(&dm_device.ha_region_list);
+	mutex_init(&dm_device.ha_region_mutex);
+	INIT_WORK(&dm_device.balloon_wrk.wrk, balloon_up);
+	INIT_WORK(&dm_device.ha_wrk.wrk, hot_add_req);
+	dm_device.host_specified_ha_region = false;
+
+	dm_device.thread =
+		 kthread_run(dm_thread_func, &dm_device, "hv_balloon");
+	if (IS_ERR(dm_device.thread)) {
+		ret = PTR_ERR(dm_device.thread);
+		goto probe_error1;
+	}
+
+#ifdef CONFIG_MEMORY_HOTPLUG
+	set_online_page_callback(&hv_online_page);
+	register_memory_notifier(&hv_memory_nb);
+#endif
+
+	hv_set_drvdata(dev, &dm_device);
+	/*
+	 * Initiate the hand shake with the host and negotiate
+	 * a version that the host can support. We start with the
+	 * highest version number and go down if the host cannot
+	 * support it.
+	 */
+	memset(&version_req, 0, sizeof(struct dm_version_request));
+	version_req.hdr.type = DM_VERSION_REQUEST;
+	version_req.hdr.size = sizeof(struct dm_version_request);
+	version_req.hdr.trans_id = atomic_inc_return(&trans_id);
+	version_req.version.version = DYNMEM_PROTOCOL_VERSION_WIN8;
+	version_req.is_last_attempt = 0;
+
+	ret = vmbus_sendpacket(dev->channel, &version_req,
+				sizeof(struct dm_version_request),
+				(unsigned long)NULL,
+				VM_PKT_DATA_INBAND, 0);
+	if (ret)
+		goto probe_error2;
+
+	t = wait_for_completion_timeout(&dm_device.host_event, 5*HZ);
+	if (t == 0) {
+		ret = -ETIMEDOUT;
+		goto probe_error2;
+	}
+
+	/*
+	 * If we could not negotiate a compatible version with the host
+	 * fail the probe function.
+	 */
+	if (dm_device.state == DM_INIT_ERROR) {
+		ret = -ETIMEDOUT;
+		goto probe_error2;
+	}
+	/*
+	 * Now submit our capabilities to the host.
+	 */
+	memset(&cap_msg, 0, sizeof(struct dm_capabilities));
+	cap_msg.hdr.type = DM_CAPABILITIES_REPORT;
+	cap_msg.hdr.size = sizeof(struct dm_capabilities);
+	cap_msg.hdr.trans_id = atomic_inc_return(&trans_id);
+
+	cap_msg.caps.cap_bits.balloon = 1;
+	cap_msg.caps.cap_bits.hot_add = 1;
+
+	/*
+	 * Specify our alignment requirements as it relates
+	 * memory hot-add. Specify 128MB alignment.
+	 */
+	cap_msg.caps.cap_bits.hot_add_alignment = 7;
+
+	/*
+	 * Currently the host does not use these
+	 * values and we set them to what is done in the
+	 * Windows driver.
+	 */
+	cap_msg.min_page_cnt = 0;
+	cap_msg.max_page_number = -1;
+
+	ret = vmbus_sendpacket(dev->channel, &cap_msg,
+				sizeof(struct dm_capabilities),
+				(unsigned long)NULL,
+				VM_PKT_DATA_INBAND, 0);
+	if (ret)
+		goto probe_error2;
+
+	t = wait_for_completion_timeout(&dm_device.host_event, 5*HZ);
+	if (t == 0) {
+		ret = -ETIMEDOUT;
+		goto probe_error2;
+	}
+
+	/*
+	 * If the host does not like our capabilities,
+	 * fail the probe function.
+	 */
+	if (dm_device.state == DM_INIT_ERROR) {
+		ret = -ETIMEDOUT;
+		goto probe_error2;
+	}
+
+	dm_device.state = DM_INITIALIZED;
+
+	return 0;
+
+probe_error2:
+#ifdef CONFIG_MEMORY_HOTPLUG
+	restore_online_page_callback(&hv_online_page);
+#endif
+	kthread_stop(dm_device.thread);
+
+probe_error1:
+	vmbus_close(dev->channel);
+probe_error0:
+	kfree(send_buffer);
+	return ret;
+}
+
+static int balloon_remove(struct hv_device *dev)
+{
+	struct hv_dynmem_device *dm = hv_get_drvdata(dev);
+	struct list_head *cur, *tmp;
+	struct hv_hotadd_state *has;
+
+	if (dm->num_pages_ballooned != 0)
+		pr_warn("Ballooned pages: %d\n", dm->num_pages_ballooned);
+
+	cancel_work_sync(&dm->balloon_wrk.wrk);
+	cancel_work_sync(&dm->ha_wrk.wrk);
+
+	vmbus_close(dev->channel);
+	kthread_stop(dm->thread);
+	kfree(send_buffer);
+#ifdef CONFIG_MEMORY_HOTPLUG
+	restore_online_page_callback(&hv_online_page);
+	unregister_memory_notifier(&hv_memory_nb);
+#endif
+	list_for_each_safe(cur, tmp, &dm->ha_region_list) {
+		has = list_entry(cur, struct hv_hotadd_state, list);
+		list_del(&has->list);
+		kfree(has);
+	}
+
+	return 0;
+}
+
+static const struct hv_vmbus_device_id id_table[] = {
+	/* Dynamic Memory Class ID */
+	/* 525074DC-8985-46e2-8057-A307DC18A502 */
+	{ HV_DM_GUID, },
+	{ },
+};
+
+MODULE_DEVICE_TABLE(vmbus, id_table);
+
+static  struct hv_driver balloon_drv = {
+	.name = "hv_balloon",
+	.id_table = id_table,
+	.probe =  balloon_probe,
+	.remove =  balloon_remove,
+};
+
+static int __init init_balloon_drv(void)
+{
+
+	return vmbus_driver_register(&balloon_drv);
+}
+
+module_init(init_balloon_drv);
+
+MODULE_DESCRIPTION("Hyper-V Balloon");
+MODULE_LICENSE("GPL");
diff --git a/drivers/hv/hv_fcopy.c b/drivers/hv/hv_fcopy.c
new file mode 100644
index 000000000..cd453e4b2
--- /dev/null
+++ b/drivers/hv/hv_fcopy.c
@@ -0,0 +1,441 @@
+/*
+ * An implementation of file copy service.
+ *
+ * Copyright (C) 2014, Microsoft, Inc.
+ *
+ * Author : K. Y. Srinivasan <ksrinivasan@novell.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ * NON INFRINGEMENT.  See the GNU General Public License for more
+ * details.
+ *
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/semaphore.h>
+#include <linux/fs.h>
+#include <linux/nls.h>
+#include <linux/workqueue.h>
+#include <linux/cdev.h>
+#include <linux/hyperv.h>
+#include <linux/sched.h>
+#include <linux/uaccess.h>
+#include <linux/miscdevice.h>
+
+#include "hyperv_vmbus.h"
+
+#define WIN8_SRV_MAJOR		1
+#define WIN8_SRV_MINOR		1
+#define WIN8_SRV_VERSION	(WIN8_SRV_MAJOR << 16 | WIN8_SRV_MINOR)
+
+/*
+ * Global state maintained for transaction that is being processed.
+ * For a class of integration services, including the "file copy service",
+ * the specified protocol is a "request/response" protocol which means that
+ * there can only be single outstanding transaction from the host at any
+ * given point in time. We use this to simplify memory management in this
+ * driver - we cache and process only one message at a time.
+ *
+ * While the request/response protocol is guaranteed by the host, we further
+ * ensure this by serializing packet processing in this driver - we do not
+ * read additional packets from the VMBUs until the current packet is fully
+ * handled.
+ *
+ * The transaction "active" state is set when we receive a request from the
+ * host and we cleanup this state when the transaction is completed - when we
+ * respond to the host with our response. When the transaction active state is
+ * set, we defer handling incoming packets.
+ */
+
+static struct {
+	bool active; /* transaction status - active or not */
+	int recv_len; /* number of bytes received. */
+	struct hv_fcopy_hdr  *fcopy_msg; /* current message */
+	struct hv_start_fcopy  message; /*  sent to daemon */
+	struct vmbus_channel *recv_channel; /* chn we got the request */
+	u64 recv_req_id; /* request ID. */
+	void *fcopy_context; /* for the channel callback */
+	struct semaphore read_sema;
+} fcopy_transaction;
+
+static bool opened; /* currently device opened */
+
+/*
+ * Before we can accept copy messages from the host, we need
+ * to handshake with the user level daemon. This state tracks
+ * if we are in the handshake phase.
+ */
+static bool in_hand_shake = true;
+static void fcopy_send_data(void);
+static void fcopy_respond_to_host(int error);
+static void fcopy_work_func(struct work_struct *dummy);
+static DECLARE_DELAYED_WORK(fcopy_work, fcopy_work_func);
+static u8 *recv_buffer;
+
+static void fcopy_work_func(struct work_struct *dummy)
+{
+	/*
+	 * If the timer fires, the user-mode component has not responded;
+	 * process the pending transaction.
+	 */
+	fcopy_respond_to_host(HV_E_FAIL);
+
+	/* In the case the user-space daemon crashes, hangs or is killed, we
+	 * need to down the semaphore, otherwise, after the daemon starts next
+	 * time, the obsolete data in fcopy_transaction.message or
+	 * fcopy_transaction.fcopy_msg will be used immediately.
+	 *
+	 * NOTE: fcopy_read() happens to get the semaphore (very rare)? We're
+	 * still OK, because we've reported the failure to the host.
+	 */
+	if (down_trylock(&fcopy_transaction.read_sema))
+		;
+
+}
+
+static int fcopy_handle_handshake(u32 version)
+{
+	switch (version) {
+	case FCOPY_CURRENT_VERSION:
+		break;
+	default:
+		/*
+		 * For now we will fail the registration.
+		 * If and when we have multiple versions to
+		 * deal with, we will be backward compatible.
+		 * We will add this code when needed.
+		 */
+		return -EINVAL;
+	}
+	pr_info("FCP: user-mode registering done. Daemon version: %d\n",
+		version);
+	fcopy_transaction.active = false;
+	if (fcopy_transaction.fcopy_context)
+		hv_fcopy_onchannelcallback(fcopy_transaction.fcopy_context);
+	in_hand_shake = false;
+	return 0;
+}
+
+static void fcopy_send_data(void)
+{
+	struct hv_start_fcopy *smsg_out = &fcopy_transaction.message;
+	int operation = fcopy_transaction.fcopy_msg->operation;
+	struct hv_start_fcopy *smsg_in;
+
+	/*
+	 * The  strings sent from the host are encoded in
+	 * in utf16; convert it to utf8 strings.
+	 * The host assures us that the utf16 strings will not exceed
+	 * the max lengths specified. We will however, reserve room
+	 * for the string terminating character - in the utf16s_utf8s()
+	 * function we limit the size of the buffer where the converted
+	 * string is placed to W_MAX_PATH -1 to guarantee
+	 * that the strings can be properly terminated!
+	 */
+
+	switch (operation) {
+	case START_FILE_COPY:
+		memset(smsg_out, 0, sizeof(struct hv_start_fcopy));
+		smsg_out->hdr.operation = operation;
+		smsg_in = (struct hv_start_fcopy *)fcopy_transaction.fcopy_msg;
+
+		utf16s_to_utf8s((wchar_t *)smsg_in->file_name, W_MAX_PATH,
+				UTF16_LITTLE_ENDIAN,
+				(__u8 *)smsg_out->file_name, W_MAX_PATH - 1);
+
+		utf16s_to_utf8s((wchar_t *)smsg_in->path_name, W_MAX_PATH,
+				UTF16_LITTLE_ENDIAN,
+				(__u8 *)smsg_out->path_name, W_MAX_PATH - 1);
+
+		smsg_out->copy_flags = smsg_in->copy_flags;
+		smsg_out->file_size = smsg_in->file_size;
+		break;
+
+	default:
+		break;
+	}
+	up(&fcopy_transaction.read_sema);
+	return;
+}
+
+/*
+ * Send a response back to the host.
+ */
+
+static void
+fcopy_respond_to_host(int error)
+{
+	struct icmsg_hdr *icmsghdr;
+	u32 buf_len;
+	struct vmbus_channel *channel;
+	u64 req_id;
+
+	/*
+	 * Copy the global state for completing the transaction. Note that
+	 * only one transaction can be active at a time. This is guaranteed
+	 * by the file copy protocol implemented by the host. Furthermore,
+	 * the "transaction active" state we maintain ensures that there can
+	 * only be one active transaction at a time.
+	 */
+
+	buf_len = fcopy_transaction.recv_len;
+	channel = fcopy_transaction.recv_channel;
+	req_id = fcopy_transaction.recv_req_id;
+
+	fcopy_transaction.active = false;
+
+	icmsghdr = (struct icmsg_hdr *)
+			&recv_buffer[sizeof(struct vmbuspipe_hdr)];
+
+	if (channel->onchannel_callback == NULL)
+		/*
+		 * We have raced with util driver being unloaded;
+		 * silently return.
+		 */
+		return;
+
+	icmsghdr->status = error;
+	icmsghdr->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
+	vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
+				VM_PKT_DATA_INBAND, 0);
+}
+
+void hv_fcopy_onchannelcallback(void *context)
+{
+	struct vmbus_channel *channel = context;
+	u32 recvlen;
+	u64 requestid;
+	struct hv_fcopy_hdr *fcopy_msg;
+	struct icmsg_hdr *icmsghdr;
+	struct icmsg_negotiate *negop = NULL;
+	int util_fw_version;
+	int fcopy_srv_version;
+
+	if (fcopy_transaction.active) {
+		/*
+		 * We will defer processing this callback once
+		 * the current transaction is complete.
+		 */
+		fcopy_transaction.fcopy_context = context;
+		return;
+	}
+
+	vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen,
+			 &requestid);
+	if (recvlen <= 0)
+		return;
+
+	icmsghdr = (struct icmsg_hdr *)&recv_buffer[
+			sizeof(struct vmbuspipe_hdr)];
+	if (icmsghdr->icmsgtype == ICMSGTYPE_NEGOTIATE) {
+		util_fw_version = UTIL_FW_VERSION;
+		fcopy_srv_version = WIN8_SRV_VERSION;
+		vmbus_prep_negotiate_resp(icmsghdr, negop, recv_buffer,
+				util_fw_version, fcopy_srv_version);
+	} else {
+		fcopy_msg = (struct hv_fcopy_hdr *)&recv_buffer[
+				sizeof(struct vmbuspipe_hdr) +
+				sizeof(struct icmsg_hdr)];
+
+		/*
+		 * Stash away this global state for completing the
+		 * transaction; note transactions are serialized.
+		 */
+
+		fcopy_transaction.active = true;
+		fcopy_transaction.recv_len = recvlen;
+		fcopy_transaction.recv_channel = channel;
+		fcopy_transaction.recv_req_id = requestid;
+		fcopy_transaction.fcopy_msg = fcopy_msg;
+
+		/*
+		 * Send the information to the user-level daemon.
+		 */
+		schedule_delayed_work(&fcopy_work, 5*HZ);
+		fcopy_send_data();
+		return;
+	}
+	icmsghdr->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
+	vmbus_sendpacket(channel, recv_buffer, recvlen, requestid,
+			VM_PKT_DATA_INBAND, 0);
+}
+
+/*
+ * Create a char device that can support read/write for passing
+ * the payload.
+ */
+
+static ssize_t fcopy_read(struct file *file, char __user *buf,
+		size_t count, loff_t *ppos)
+{
+	void *src;
+	size_t copy_size;
+	int operation;
+
+	/*
+	 * Wait until there is something to be read.
+	 */
+	if (down_interruptible(&fcopy_transaction.read_sema))
+		return -EINTR;
+
+	/*
+	 * The channel may be rescinded and in this case, we will wakeup the
+	 * the thread blocked on the semaphore and we will use the opened
+	 * state to correctly handle this case.
+	 */
+	if (!opened)
+		return -ENODEV;
+
+	operation = fcopy_transaction.fcopy_msg->operation;
+
+	if (operation == START_FILE_COPY) {
+		src = &fcopy_transaction.message;
+		copy_size = sizeof(struct hv_start_fcopy);
+		if (count < copy_size)
+			return 0;
+	} else {
+		src = fcopy_transaction.fcopy_msg;
+		copy_size = sizeof(struct hv_do_fcopy);
+		if (count < copy_size)
+			return 0;
+	}
+	if (copy_to_user(buf, src, copy_size))
+		return -EFAULT;
+
+	return copy_size;
+}
+
+static ssize_t fcopy_write(struct file *file, const char __user *buf,
+			size_t count, loff_t *ppos)
+{
+	int response = 0;
+
+	if (count != sizeof(int))
+		return -EINVAL;
+
+	if (copy_from_user(&response, buf, sizeof(int)))
+		return -EFAULT;
+
+	if (in_hand_shake) {
+		if (fcopy_handle_handshake(response))
+			return -EINVAL;
+		return sizeof(int);
+	}
+
+	/*
+	 * Complete the transaction by forwarding the result
+	 * to the host. But first, cancel the timeout.
+	 */
+	if (cancel_delayed_work_sync(&fcopy_work))
+		fcopy_respond_to_host(response);
+
+	return sizeof(int);
+}
+
+static int fcopy_open(struct inode *inode, struct file *f)
+{
+	/*
+	 * The user level daemon that will open this device is
+	 * really an extension of this driver. We can have only
+	 * active open at a time.
+	 */
+	if (opened)
+		return -EBUSY;
+
+	/*
+	 * The daemon is alive; setup the state.
+	 */
+	opened = true;
+	return 0;
+}
+
+/* XXX: there are still some tricky corner cases, e.g.,
+ * 1) In a SMP guest, when fcopy_release() runs between
+ * schedule_delayed_work() and fcopy_send_data(), there is
+ * still a chance an obsolete message will be queued.
+ *
+ * 2) When the fcopy daemon is running, if we unload the driver,
+ * we'll notice a kernel oops when we kill the daemon later.
+ */
+static int fcopy_release(struct inode *inode, struct file *f)
+{
+	/*
+	 * The daemon has exited; reset the state.
+	 */
+	in_hand_shake = true;
+	opened = false;
+
+	if (cancel_delayed_work_sync(&fcopy_work)) {
+		/* We haven't up()-ed the semaphore(very rare)? */
+		if (down_trylock(&fcopy_transaction.read_sema))
+			;
+		fcopy_respond_to_host(HV_E_FAIL);
+	}
+	return 0;
+}
+
+
+static const struct file_operations fcopy_fops = {
+	.read           = fcopy_read,
+	.write          = fcopy_write,
+	.release	= fcopy_release,
+	.open		= fcopy_open,
+};
+
+static struct miscdevice fcopy_misc = {
+	.minor          = MISC_DYNAMIC_MINOR,
+	.name           = "vmbus/hv_fcopy",
+	.fops           = &fcopy_fops,
+};
+
+static int fcopy_dev_init(void)
+{
+	return misc_register(&fcopy_misc);
+}
+
+static void fcopy_dev_deinit(void)
+{
+
+	/*
+	 * The device is going away - perhaps because the
+	 * host has rescinded the channel. Setup state so that
+	 * user level daemon can gracefully exit if it is blocked
+	 * on the read semaphore.
+	 */
+	opened = false;
+	/*
+	 * Signal the semaphore as the device is
+	 * going away.
+	 */
+	up(&fcopy_transaction.read_sema);
+	misc_deregister(&fcopy_misc);
+}
+
+int hv_fcopy_init(struct hv_util_service *srv)
+{
+	recv_buffer = srv->recv_buffer;
+
+	/*
+	 * When this driver loads, the user level daemon that
+	 * processes the host requests may not yet be running.
+	 * Defer processing channel callbacks until the daemon
+	 * has registered.
+	 */
+	fcopy_transaction.active = true;
+	sema_init(&fcopy_transaction.read_sema, 0);
+
+	return fcopy_dev_init();
+}
+
+void hv_fcopy_deinit(void)
+{
+	cancel_delayed_work_sync(&fcopy_work);
+	fcopy_dev_deinit();
+}
diff --git a/drivers/hv/hv_kvp.c b/drivers/hv/hv_kvp.c
new file mode 100644
index 000000000..beb8105c0
--- /dev/null
+++ b/drivers/hv/hv_kvp.c
@@ -0,0 +1,722 @@
+/*
+ * An implementation of key value pair (KVP) functionality for Linux.
+ *
+ *
+ * Copyright (C) 2010, Novell, Inc.
+ * Author : K. Y. Srinivasan <ksrinivasan@novell.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ * NON INFRINGEMENT.  See the GNU General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/net.h>
+#include <linux/nls.h>
+#include <linux/connector.h>
+#include <linux/workqueue.h>
+#include <linux/hyperv.h>
+
+
+/*
+ * Pre win8 version numbers used in ws2008 and ws 2008 r2 (win7)
+ */
+#define WS2008_SRV_MAJOR	1
+#define WS2008_SRV_MINOR	0
+#define WS2008_SRV_VERSION     (WS2008_SRV_MAJOR << 16 | WS2008_SRV_MINOR)
+
+#define WIN7_SRV_MAJOR   3
+#define WIN7_SRV_MINOR   0
+#define WIN7_SRV_VERSION     (WIN7_SRV_MAJOR << 16 | WIN7_SRV_MINOR)
+
+#define WIN8_SRV_MAJOR   4
+#define WIN8_SRV_MINOR   0
+#define WIN8_SRV_VERSION     (WIN8_SRV_MAJOR << 16 | WIN8_SRV_MINOR)
+
+/*
+ * Global state maintained for transaction that is being processed.
+ * Note that only one transaction can be active at any point in time.
+ *
+ * This state is set when we receive a request from the host; we
+ * cleanup this state when the transaction is completed - when we respond
+ * to the host with the key value.
+ */
+
+static struct {
+	bool active; /* transaction status - active or not */
+	int recv_len; /* number of bytes received. */
+	struct hv_kvp_msg  *kvp_msg; /* current message */
+	struct vmbus_channel *recv_channel; /* chn we got the request */
+	u64 recv_req_id; /* request ID. */
+	void *kvp_context; /* for the channel callback */
+} kvp_transaction;
+
+/*
+ * Before we can accept KVP messages from the host, we need
+ * to handshake with the user level daemon. This state tracks
+ * if we are in the handshake phase.
+ */
+static bool in_hand_shake = true;
+
+/*
+ * This state maintains the version number registered by the daemon.
+ */
+static int dm_reg_value;
+
+static void kvp_send_key(struct work_struct *dummy);
+
+
+static void kvp_respond_to_host(struct hv_kvp_msg *msg, int error);
+static void kvp_work_func(struct work_struct *dummy);
+static void kvp_register(int);
+
+static DECLARE_DELAYED_WORK(kvp_work, kvp_work_func);
+static DECLARE_WORK(kvp_sendkey_work, kvp_send_key);
+
+static struct cb_id kvp_id = { CN_KVP_IDX, CN_KVP_VAL };
+static const char kvp_name[] = "kvp_kernel_module";
+static u8 *recv_buffer;
+/*
+ * Register the kernel component with the user-level daemon.
+ * As part of this registration, pass the LIC version number.
+ * This number has no meaning, it satisfies the registration protocol.
+ */
+#define HV_DRV_VERSION           "3.1"
+
+static void
+kvp_register(int reg_value)
+{
+
+	struct cn_msg *msg;
+	struct hv_kvp_msg *kvp_msg;
+	char *version;
+
+	msg = kzalloc(sizeof(*msg) + sizeof(struct hv_kvp_msg), GFP_ATOMIC);
+
+	if (msg) {
+		kvp_msg = (struct hv_kvp_msg *)msg->data;
+		version = kvp_msg->body.kvp_register.version;
+		msg->id.idx =  CN_KVP_IDX;
+		msg->id.val = CN_KVP_VAL;
+
+		kvp_msg->kvp_hdr.operation = reg_value;
+		strcpy(version, HV_DRV_VERSION);
+		msg->len = sizeof(struct hv_kvp_msg);
+		cn_netlink_send(msg, 0, 0, GFP_ATOMIC);
+		kfree(msg);
+	}
+}
+static void
+kvp_work_func(struct work_struct *dummy)
+{
+	/*
+	 * If the timer fires, the user-mode component has not responded;
+	 * process the pending transaction.
+	 */
+	kvp_respond_to_host(NULL, HV_E_FAIL);
+}
+
+static void poll_channel(struct vmbus_channel *channel)
+{
+	if (channel->target_cpu != smp_processor_id())
+		smp_call_function_single(channel->target_cpu,
+					 hv_kvp_onchannelcallback,
+					 channel, true);
+	else
+		hv_kvp_onchannelcallback(channel);
+}
+
+
+static int kvp_handle_handshake(struct hv_kvp_msg *msg)
+{
+	int ret = 1;
+
+	switch (msg->kvp_hdr.operation) {
+	case KVP_OP_REGISTER:
+		dm_reg_value = KVP_OP_REGISTER;
+		pr_info("KVP: IP injection functionality not available\n");
+		pr_info("KVP: Upgrade the KVP daemon\n");
+		break;
+	case KVP_OP_REGISTER1:
+		dm_reg_value = KVP_OP_REGISTER1;
+		break;
+	default:
+		pr_info("KVP: incompatible daemon\n");
+		pr_info("KVP: KVP version: %d, Daemon version: %d\n",
+			KVP_OP_REGISTER1, msg->kvp_hdr.operation);
+		ret = 0;
+	}
+
+	if (ret) {
+		/*
+		 * We have a compatible daemon; complete the handshake.
+		 */
+		pr_info("KVP: user-mode registering done.\n");
+		kvp_register(dm_reg_value);
+		kvp_transaction.active = false;
+		if (kvp_transaction.kvp_context)
+			poll_channel(kvp_transaction.kvp_context);
+	}
+	return ret;
+}
+
+
+/*
+ * Callback when data is received from user mode.
+ */
+
+static void
+kvp_cn_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp)
+{
+	struct hv_kvp_msg *message;
+	struct hv_kvp_msg_enumerate *data;
+	int	error = 0;
+
+	message = (struct hv_kvp_msg *)msg->data;
+
+	/*
+	 * If we are negotiating the version information
+	 * with the daemon; handle that first.
+	 */
+
+	if (in_hand_shake) {
+		if (kvp_handle_handshake(message))
+			in_hand_shake = false;
+		return;
+	}
+
+	/*
+	 * Based on the version of the daemon, we propagate errors from the
+	 * daemon differently.
+	 */
+
+	data = &message->body.kvp_enum_data;
+
+	switch (dm_reg_value) {
+	case KVP_OP_REGISTER:
+		/*
+		 * Null string is used to pass back error condition.
+		 */
+		if (data->data.key[0] == 0)
+			error = HV_S_CONT;
+		break;
+
+	case KVP_OP_REGISTER1:
+		/*
+		 * We use the message header information from
+		 * the user level daemon to transmit errors.
+		 */
+		error = message->error;
+		break;
+	}
+
+	/*
+	 * Complete the transaction by forwarding the key value
+	 * to the host. But first, cancel the timeout.
+	 */
+	if (cancel_delayed_work_sync(&kvp_work))
+		kvp_respond_to_host(message, error);
+}
+
+
+static int process_ob_ipinfo(void *in_msg, void *out_msg, int op)
+{
+	struct hv_kvp_msg *in = in_msg;
+	struct hv_kvp_ip_msg *out = out_msg;
+	int len;
+
+	switch (op) {
+	case KVP_OP_GET_IP_INFO:
+		/*
+		 * Transform all parameters into utf16 encoding.
+		 */
+		len = utf8s_to_utf16s((char *)in->body.kvp_ip_val.ip_addr,
+				strlen((char *)in->body.kvp_ip_val.ip_addr),
+				UTF16_HOST_ENDIAN,
+				(wchar_t *)out->kvp_ip_val.ip_addr,
+				MAX_IP_ADDR_SIZE);
+		if (len < 0)
+			return len;
+
+		len = utf8s_to_utf16s((char *)in->body.kvp_ip_val.sub_net,
+				strlen((char *)in->body.kvp_ip_val.sub_net),
+				UTF16_HOST_ENDIAN,
+				(wchar_t *)out->kvp_ip_val.sub_net,
+				MAX_IP_ADDR_SIZE);
+		if (len < 0)
+			return len;
+
+		len = utf8s_to_utf16s((char *)in->body.kvp_ip_val.gate_way,
+				strlen((char *)in->body.kvp_ip_val.gate_way),
+				UTF16_HOST_ENDIAN,
+				(wchar_t *)out->kvp_ip_val.gate_way,
+				MAX_GATEWAY_SIZE);
+		if (len < 0)
+			return len;
+
+		len = utf8s_to_utf16s((char *)in->body.kvp_ip_val.dns_addr,
+				strlen((char *)in->body.kvp_ip_val.dns_addr),
+				UTF16_HOST_ENDIAN,
+				(wchar_t *)out->kvp_ip_val.dns_addr,
+				MAX_IP_ADDR_SIZE);
+		if (len < 0)
+			return len;
+
+		len = utf8s_to_utf16s((char *)in->body.kvp_ip_val.adapter_id,
+				strlen((char *)in->body.kvp_ip_val.adapter_id),
+				UTF16_HOST_ENDIAN,
+				(wchar_t *)out->kvp_ip_val.adapter_id,
+				MAX_IP_ADDR_SIZE);
+		if (len < 0)
+			return len;
+
+		out->kvp_ip_val.dhcp_enabled =
+			in->body.kvp_ip_val.dhcp_enabled;
+		out->kvp_ip_val.addr_family =
+			in->body.kvp_ip_val.addr_family;
+	}
+
+	return 0;
+}
+
+static void process_ib_ipinfo(void *in_msg, void *out_msg, int op)
+{
+	struct hv_kvp_ip_msg *in = in_msg;
+	struct hv_kvp_msg *out = out_msg;
+
+	switch (op) {
+	case KVP_OP_SET_IP_INFO:
+		/*
+		 * Transform all parameters into utf8 encoding.
+		 */
+		utf16s_to_utf8s((wchar_t *)in->kvp_ip_val.ip_addr,
+				MAX_IP_ADDR_SIZE,
+				UTF16_LITTLE_ENDIAN,
+				(__u8 *)out->body.kvp_ip_val.ip_addr,
+				MAX_IP_ADDR_SIZE);
+
+		utf16s_to_utf8s((wchar_t *)in->kvp_ip_val.sub_net,
+				MAX_IP_ADDR_SIZE,
+				UTF16_LITTLE_ENDIAN,
+				(__u8 *)out->body.kvp_ip_val.sub_net,
+				MAX_IP_ADDR_SIZE);
+
+		utf16s_to_utf8s((wchar_t *)in->kvp_ip_val.gate_way,
+				MAX_GATEWAY_SIZE,
+				UTF16_LITTLE_ENDIAN,
+				(__u8 *)out->body.kvp_ip_val.gate_way,
+				MAX_GATEWAY_SIZE);
+
+		utf16s_to_utf8s((wchar_t *)in->kvp_ip_val.dns_addr,
+				MAX_IP_ADDR_SIZE,
+				UTF16_LITTLE_ENDIAN,
+				(__u8 *)out->body.kvp_ip_val.dns_addr,
+				MAX_IP_ADDR_SIZE);
+
+		out->body.kvp_ip_val.dhcp_enabled = in->kvp_ip_val.dhcp_enabled;
+
+	default:
+		utf16s_to_utf8s((wchar_t *)in->kvp_ip_val.adapter_id,
+				MAX_ADAPTER_ID_SIZE,
+				UTF16_LITTLE_ENDIAN,
+				(__u8 *)out->body.kvp_ip_val.adapter_id,
+				MAX_ADAPTER_ID_SIZE);
+
+		out->body.kvp_ip_val.addr_family = in->kvp_ip_val.addr_family;
+	}
+}
+
+
+
+
+static void
+kvp_send_key(struct work_struct *dummy)
+{
+	struct cn_msg *msg;
+	struct hv_kvp_msg *message;
+	struct hv_kvp_msg *in_msg;
+	__u8 operation = kvp_transaction.kvp_msg->kvp_hdr.operation;
+	__u8 pool = kvp_transaction.kvp_msg->kvp_hdr.pool;
+	__u32 val32;
+	__u64 val64;
+	int rc;
+
+	msg = kzalloc(sizeof(*msg) + sizeof(struct hv_kvp_msg) , GFP_ATOMIC);
+	if (!msg)
+		return;
+
+	msg->id.idx =  CN_KVP_IDX;
+	msg->id.val = CN_KVP_VAL;
+
+	message = (struct hv_kvp_msg *)msg->data;
+	message->kvp_hdr.operation = operation;
+	message->kvp_hdr.pool = pool;
+	in_msg = kvp_transaction.kvp_msg;
+
+	/*
+	 * The key/value strings sent from the host are encoded in
+	 * in utf16; convert it to utf8 strings.
+	 * The host assures us that the utf16 strings will not exceed
+	 * the max lengths specified. We will however, reserve room
+	 * for the string terminating character - in the utf16s_utf8s()
+	 * function we limit the size of the buffer where the converted
+	 * string is placed to HV_KVP_EXCHANGE_MAX_*_SIZE -1 to gaurantee
+	 * that the strings can be properly terminated!
+	 */
+
+	switch (message->kvp_hdr.operation) {
+	case KVP_OP_SET_IP_INFO:
+		process_ib_ipinfo(in_msg, message, KVP_OP_SET_IP_INFO);
+		break;
+	case KVP_OP_GET_IP_INFO:
+		process_ib_ipinfo(in_msg, message, KVP_OP_GET_IP_INFO);
+		break;
+	case KVP_OP_SET:
+		switch (in_msg->body.kvp_set.data.value_type) {
+		case REG_SZ:
+			/*
+			 * The value is a string - utf16 encoding.
+			 */
+			message->body.kvp_set.data.value_size =
+				utf16s_to_utf8s(
+				(wchar_t *)in_msg->body.kvp_set.data.value,
+				in_msg->body.kvp_set.data.value_size,
+				UTF16_LITTLE_ENDIAN,
+				message->body.kvp_set.data.value,
+				HV_KVP_EXCHANGE_MAX_VALUE_SIZE - 1) + 1;
+				break;
+
+		case REG_U32:
+			/*
+			 * The value is a 32 bit scalar.
+			 * We save this as a utf8 string.
+			 */
+			val32 = in_msg->body.kvp_set.data.value_u32;
+			message->body.kvp_set.data.value_size =
+				sprintf(message->body.kvp_set.data.value,
+					"%d", val32) + 1;
+			break;
+
+		case REG_U64:
+			/*
+			 * The value is a 64 bit scalar.
+			 * We save this as a utf8 string.
+			 */
+			val64 = in_msg->body.kvp_set.data.value_u64;
+			message->body.kvp_set.data.value_size =
+				sprintf(message->body.kvp_set.data.value,
+					"%llu", val64) + 1;
+			break;
+
+		}
+	case KVP_OP_GET:
+		message->body.kvp_set.data.key_size =
+			utf16s_to_utf8s(
+			(wchar_t *)in_msg->body.kvp_set.data.key,
+			in_msg->body.kvp_set.data.key_size,
+			UTF16_LITTLE_ENDIAN,
+			message->body.kvp_set.data.key,
+			HV_KVP_EXCHANGE_MAX_KEY_SIZE - 1) + 1;
+			break;
+
+	case KVP_OP_DELETE:
+		message->body.kvp_delete.key_size =
+			utf16s_to_utf8s(
+			(wchar_t *)in_msg->body.kvp_delete.key,
+			in_msg->body.kvp_delete.key_size,
+			UTF16_LITTLE_ENDIAN,
+			message->body.kvp_delete.key,
+			HV_KVP_EXCHANGE_MAX_KEY_SIZE - 1) + 1;
+			break;
+
+	case KVP_OP_ENUMERATE:
+		message->body.kvp_enum_data.index =
+			in_msg->body.kvp_enum_data.index;
+			break;
+	}
+
+	msg->len = sizeof(struct hv_kvp_msg);
+	rc = cn_netlink_send(msg, 0, 0, GFP_ATOMIC);
+	if (rc) {
+		pr_debug("KVP: failed to communicate to the daemon: %d\n", rc);
+		if (cancel_delayed_work_sync(&kvp_work))
+			kvp_respond_to_host(message, HV_E_FAIL);
+	}
+
+	kfree(msg);
+
+	return;
+}
+
+/*
+ * Send a response back to the host.
+ */
+
+static void
+kvp_respond_to_host(struct hv_kvp_msg *msg_to_host, int error)
+{
+	struct hv_kvp_msg  *kvp_msg;
+	struct hv_kvp_exchg_msg_value  *kvp_data;
+	char	*key_name;
+	char	*value;
+	struct icmsg_hdr *icmsghdrp;
+	int	keylen = 0;
+	int	valuelen = 0;
+	u32	buf_len;
+	struct vmbus_channel *channel;
+	u64	req_id;
+	int ret;
+
+	/*
+	 * If a transaction is not active; log and return.
+	 */
+
+	if (!kvp_transaction.active) {
+		/*
+		 * This is a spurious call!
+		 */
+		pr_warn("KVP: Transaction not active\n");
+		return;
+	}
+	/*
+	 * Copy the global state for completing the transaction. Note that
+	 * only one transaction can be active at a time.
+	 */
+
+	buf_len = kvp_transaction.recv_len;
+	channel = kvp_transaction.recv_channel;
+	req_id = kvp_transaction.recv_req_id;
+
+	kvp_transaction.active = false;
+
+	icmsghdrp = (struct icmsg_hdr *)
+			&recv_buffer[sizeof(struct vmbuspipe_hdr)];
+
+	if (channel->onchannel_callback == NULL)
+		/*
+		 * We have raced with util driver being unloaded;
+		 * silently return.
+		 */
+		return;
+
+	icmsghdrp->status = error;
+
+	/*
+	 * If the error parameter is set, terminate the host's enumeration
+	 * on this pool.
+	 */
+	if (error) {
+		/*
+		 * Something failed or we have timedout;
+		 * terminate the current host-side iteration.
+		 */
+		goto response_done;
+	}
+
+	kvp_msg = (struct hv_kvp_msg *)
+			&recv_buffer[sizeof(struct vmbuspipe_hdr) +
+			sizeof(struct icmsg_hdr)];
+
+	switch (kvp_transaction.kvp_msg->kvp_hdr.operation) {
+	case KVP_OP_GET_IP_INFO:
+		ret = process_ob_ipinfo(msg_to_host,
+				 (struct hv_kvp_ip_msg *)kvp_msg,
+				 KVP_OP_GET_IP_INFO);
+		if (ret < 0)
+			icmsghdrp->status = HV_E_FAIL;
+
+		goto response_done;
+	case KVP_OP_SET_IP_INFO:
+		goto response_done;
+	case KVP_OP_GET:
+		kvp_data = &kvp_msg->body.kvp_get.data;
+		goto copy_value;
+
+	case KVP_OP_SET:
+	case KVP_OP_DELETE:
+		goto response_done;
+
+	default:
+		break;
+	}
+
+	kvp_data = &kvp_msg->body.kvp_enum_data.data;
+	key_name = msg_to_host->body.kvp_enum_data.data.key;
+
+	/*
+	 * The windows host expects the key/value pair to be encoded
+	 * in utf16. Ensure that the key/value size reported to the host
+	 * will be less than or equal to the MAX size (including the
+	 * terminating character).
+	 */
+	keylen = utf8s_to_utf16s(key_name, strlen(key_name), UTF16_HOST_ENDIAN,
+				(wchar_t *) kvp_data->key,
+				(HV_KVP_EXCHANGE_MAX_KEY_SIZE / 2) - 2);
+	kvp_data->key_size = 2*(keylen + 1); /* utf16 encoding */
+
+copy_value:
+	value = msg_to_host->body.kvp_enum_data.data.value;
+	valuelen = utf8s_to_utf16s(value, strlen(value), UTF16_HOST_ENDIAN,
+				(wchar_t *) kvp_data->value,
+				(HV_KVP_EXCHANGE_MAX_VALUE_SIZE / 2) - 2);
+	kvp_data->value_size = 2*(valuelen + 1); /* utf16 encoding */
+
+	/*
+	 * If the utf8s to utf16s conversion failed; notify host
+	 * of the error.
+	 */
+	if ((keylen < 0) || (valuelen < 0))
+		icmsghdrp->status = HV_E_FAIL;
+
+	kvp_data->value_type = REG_SZ; /* all our values are strings */
+
+response_done:
+	icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
+
+	vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
+				VM_PKT_DATA_INBAND, 0);
+	poll_channel(channel);
+}
+
+/*
+ * This callback is invoked when we get a KVP message from the host.
+ * The host ensures that only one KVP transaction can be active at a time.
+ * KVP implementation in Linux needs to forward the key to a user-mde
+ * component to retrive the corresponding value. Consequently, we cannot
+ * respond to the host in the conext of this callback. Since the host
+ * guarantees that at most only one transaction can be active at a time,
+ * we stash away the transaction state in a set of global variables.
+ */
+
+void hv_kvp_onchannelcallback(void *context)
+{
+	struct vmbus_channel *channel = context;
+	u32 recvlen;
+	u64 requestid;
+
+	struct hv_kvp_msg *kvp_msg;
+
+	struct icmsg_hdr *icmsghdrp;
+	struct icmsg_negotiate *negop = NULL;
+	int util_fw_version;
+	int kvp_srv_version;
+
+	if (kvp_transaction.active) {
+		/*
+		 * We will defer processing this callback once
+		 * the current transaction is complete.
+		 */
+		kvp_transaction.kvp_context = context;
+		return;
+	}
+
+	vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 4, &recvlen,
+			 &requestid);
+
+	if (recvlen > 0) {
+		icmsghdrp = (struct icmsg_hdr *)&recv_buffer[
+			sizeof(struct vmbuspipe_hdr)];
+
+		if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
+			/*
+			 * Based on the host, select appropriate
+			 * framework and service versions we will
+			 * negotiate.
+			 */
+			switch (vmbus_proto_version) {
+			case (VERSION_WS2008):
+				util_fw_version = UTIL_WS2K8_FW_VERSION;
+				kvp_srv_version = WS2008_SRV_VERSION;
+				break;
+			case (VERSION_WIN7):
+				util_fw_version = UTIL_FW_VERSION;
+				kvp_srv_version = WIN7_SRV_VERSION;
+				break;
+			default:
+				util_fw_version = UTIL_FW_VERSION;
+				kvp_srv_version = WIN8_SRV_VERSION;
+			}
+			vmbus_prep_negotiate_resp(icmsghdrp, negop,
+				 recv_buffer, util_fw_version,
+				 kvp_srv_version);
+
+		} else {
+			kvp_msg = (struct hv_kvp_msg *)&recv_buffer[
+				sizeof(struct vmbuspipe_hdr) +
+				sizeof(struct icmsg_hdr)];
+
+			/*
+			 * Stash away this global state for completing the
+			 * transaction; note transactions are serialized.
+			 */
+
+			kvp_transaction.recv_len = recvlen;
+			kvp_transaction.recv_channel = channel;
+			kvp_transaction.recv_req_id = requestid;
+			kvp_transaction.active = true;
+			kvp_transaction.kvp_msg = kvp_msg;
+
+			/*
+			 * Get the information from the
+			 * user-mode component.
+			 * component. This transaction will be
+			 * completed when we get the value from
+			 * the user-mode component.
+			 * Set a timeout to deal with
+			 * user-mode not responding.
+			 */
+			schedule_work(&kvp_sendkey_work);
+			schedule_delayed_work(&kvp_work, 5*HZ);
+
+			return;
+
+		}
+
+		icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
+			| ICMSGHDRFLAG_RESPONSE;
+
+		vmbus_sendpacket(channel, recv_buffer,
+				       recvlen, requestid,
+				       VM_PKT_DATA_INBAND, 0);
+	}
+
+}
+
+int
+hv_kvp_init(struct hv_util_service *srv)
+{
+	int err;
+
+	err = cn_add_callback(&kvp_id, kvp_name, kvp_cn_callback);
+	if (err)
+		return err;
+	recv_buffer = srv->recv_buffer;
+
+	/*
+	 * When this driver loads, the user level daemon that
+	 * processes the host requests may not yet be running.
+	 * Defer processing channel callbacks until the daemon
+	 * has registered.
+	 */
+	kvp_transaction.active = true;
+
+	return 0;
+}
+
+void hv_kvp_deinit(void)
+{
+	cn_del_callback(&kvp_id);
+	cancel_delayed_work_sync(&kvp_work);
+	cancel_work_sync(&kvp_sendkey_work);
+}
diff --git a/drivers/hv/hv_snapshot.c b/drivers/hv/hv_snapshot.c
new file mode 100644
index 000000000..9d5e0d1ef
--- /dev/null
+++ b/drivers/hv/hv_snapshot.c
@@ -0,0 +1,303 @@
+/*
+ * An implementation of host initiated guest snapshot.
+ *
+ *
+ * Copyright (C) 2013, Microsoft, Inc.
+ * Author : K. Y. Srinivasan <kys@microsoft.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ * NON INFRINGEMENT.  See the GNU General Public License for more
+ * details.
+ *
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/net.h>
+#include <linux/nls.h>
+#include <linux/connector.h>
+#include <linux/workqueue.h>
+#include <linux/hyperv.h>
+
+#define VSS_MAJOR  5
+#define VSS_MINOR  0
+#define VSS_VERSION    (VSS_MAJOR << 16 | VSS_MINOR)
+
+#define VSS_USERSPACE_TIMEOUT (msecs_to_jiffies(10 * 1000))
+
+/*
+ * Global state maintained for transaction that is being processed.
+ * Note that only one transaction can be active at any point in time.
+ *
+ * This state is set when we receive a request from the host; we
+ * cleanup this state when the transaction is completed - when we respond
+ * to the host with the key value.
+ */
+
+static struct {
+	bool active; /* transaction status - active or not */
+	int recv_len; /* number of bytes received. */
+	struct vmbus_channel *recv_channel; /* chn we got the request */
+	u64 recv_req_id; /* request ID. */
+	struct hv_vss_msg  *msg; /* current message */
+} vss_transaction;
+
+
+static void vss_respond_to_host(int error);
+
+static struct cb_id vss_id = { CN_VSS_IDX, CN_VSS_VAL };
+static const char vss_name[] = "vss_kernel_module";
+static __u8 *recv_buffer;
+
+static void vss_send_op(struct work_struct *dummy);
+static void vss_timeout_func(struct work_struct *dummy);
+
+static DECLARE_DELAYED_WORK(vss_timeout_work, vss_timeout_func);
+static DECLARE_WORK(vss_send_op_work, vss_send_op);
+
+/*
+ * Callback when data is received from user mode.
+ */
+
+static void vss_timeout_func(struct work_struct *dummy)
+{
+	/*
+	 * Timeout waiting for userspace component to reply happened.
+	 */
+	pr_warn("VSS: timeout waiting for daemon to reply\n");
+	vss_respond_to_host(HV_E_FAIL);
+}
+
+static void
+vss_cn_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp)
+{
+	struct hv_vss_msg *vss_msg;
+
+	vss_msg = (struct hv_vss_msg *)msg->data;
+
+	if (vss_msg->vss_hdr.operation == VSS_OP_REGISTER) {
+		pr_info("VSS daemon registered\n");
+		vss_transaction.active = false;
+		if (vss_transaction.recv_channel != NULL)
+			hv_vss_onchannelcallback(vss_transaction.recv_channel);
+		return;
+
+	}
+	if (cancel_delayed_work_sync(&vss_timeout_work))
+		vss_respond_to_host(vss_msg->error);
+}
+
+
+static void vss_send_op(struct work_struct *dummy)
+{
+	int op = vss_transaction.msg->vss_hdr.operation;
+	int rc;
+	struct cn_msg *msg;
+	struct hv_vss_msg *vss_msg;
+
+	msg = kzalloc(sizeof(*msg) + sizeof(*vss_msg), GFP_ATOMIC);
+	if (!msg)
+		return;
+
+	vss_msg = (struct hv_vss_msg *)msg->data;
+
+	msg->id.idx =  CN_VSS_IDX;
+	msg->id.val = CN_VSS_VAL;
+
+	vss_msg->vss_hdr.operation = op;
+	msg->len = sizeof(struct hv_vss_msg);
+
+	rc = cn_netlink_send(msg, 0, 0, GFP_ATOMIC);
+	if (rc) {
+		pr_warn("VSS: failed to communicate to the daemon: %d\n", rc);
+		if (cancel_delayed_work_sync(&vss_timeout_work))
+			vss_respond_to_host(HV_E_FAIL);
+	}
+	kfree(msg);
+
+	return;
+}
+
+/*
+ * Send a response back to the host.
+ */
+
+static void
+vss_respond_to_host(int error)
+{
+	struct icmsg_hdr *icmsghdrp;
+	u32	buf_len;
+	struct vmbus_channel *channel;
+	u64	req_id;
+
+	/*
+	 * If a transaction is not active; log and return.
+	 */
+
+	if (!vss_transaction.active) {
+		/*
+		 * This is a spurious call!
+		 */
+		pr_warn("VSS: Transaction not active\n");
+		return;
+	}
+	/*
+	 * Copy the global state for completing the transaction. Note that
+	 * only one transaction can be active at a time.
+	 */
+
+	buf_len = vss_transaction.recv_len;
+	channel = vss_transaction.recv_channel;
+	req_id = vss_transaction.recv_req_id;
+	vss_transaction.active = false;
+
+	icmsghdrp = (struct icmsg_hdr *)
+			&recv_buffer[sizeof(struct vmbuspipe_hdr)];
+
+	if (channel->onchannel_callback == NULL)
+		/*
+		 * We have raced with util driver being unloaded;
+		 * silently return.
+		 */
+		return;
+
+	icmsghdrp->status = error;
+
+	icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
+
+	vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
+				VM_PKT_DATA_INBAND, 0);
+
+}
+
+/*
+ * This callback is invoked when we get a VSS message from the host.
+ * The host ensures that only one VSS transaction can be active at a time.
+ */
+
+void hv_vss_onchannelcallback(void *context)
+{
+	struct vmbus_channel *channel = context;
+	u32 recvlen;
+	u64 requestid;
+	struct hv_vss_msg *vss_msg;
+
+
+	struct icmsg_hdr *icmsghdrp;
+	struct icmsg_negotiate *negop = NULL;
+
+	if (vss_transaction.active) {
+		/*
+		 * We will defer processing this callback once
+		 * the current transaction is complete.
+		 */
+		vss_transaction.recv_channel = channel;
+		return;
+	}
+
+	vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen,
+			 &requestid);
+
+	if (recvlen > 0) {
+		icmsghdrp = (struct icmsg_hdr *)&recv_buffer[
+			sizeof(struct vmbuspipe_hdr)];
+
+		if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
+			vmbus_prep_negotiate_resp(icmsghdrp, negop,
+				 recv_buffer, UTIL_FW_VERSION,
+				 VSS_VERSION);
+		} else {
+			vss_msg = (struct hv_vss_msg *)&recv_buffer[
+				sizeof(struct vmbuspipe_hdr) +
+				sizeof(struct icmsg_hdr)];
+
+			/*
+			 * Stash away this global state for completing the
+			 * transaction; note transactions are serialized.
+			 */
+
+			vss_transaction.recv_len = recvlen;
+			vss_transaction.recv_channel = channel;
+			vss_transaction.recv_req_id = requestid;
+			vss_transaction.active = true;
+			vss_transaction.msg = (struct hv_vss_msg *)vss_msg;
+
+			switch (vss_msg->vss_hdr.operation) {
+				/*
+				 * Initiate a "freeze/thaw"
+				 * operation in the guest.
+				 * We respond to the host once
+				 * the operation is complete.
+				 *
+				 * We send the message to the
+				 * user space daemon and the
+				 * operation is performed in
+				 * the daemon.
+				 */
+			case VSS_OP_FREEZE:
+			case VSS_OP_THAW:
+				schedule_work(&vss_send_op_work);
+				schedule_delayed_work(&vss_timeout_work,
+						      VSS_USERSPACE_TIMEOUT);
+				return;
+
+			case VSS_OP_HOT_BACKUP:
+				vss_msg->vss_cf.flags =
+					 VSS_HBU_NO_AUTO_RECOVERY;
+				vss_respond_to_host(0);
+				return;
+
+			case VSS_OP_GET_DM_INFO:
+				vss_msg->dm_info.flags = 0;
+				vss_respond_to_host(0);
+				return;
+
+			default:
+				vss_respond_to_host(0);
+				return;
+
+			}
+
+		}
+
+		icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
+			| ICMSGHDRFLAG_RESPONSE;
+
+		vmbus_sendpacket(channel, recv_buffer,
+				       recvlen, requestid,
+				       VM_PKT_DATA_INBAND, 0);
+	}
+
+}
+
+int
+hv_vss_init(struct hv_util_service *srv)
+{
+	int err;
+
+	err = cn_add_callback(&vss_id, vss_name, vss_cn_callback);
+	if (err)
+		return err;
+	recv_buffer = srv->recv_buffer;
+
+	/*
+	 * When this driver loads, the user level daemon that
+	 * processes the host requests may not yet be running.
+	 * Defer processing channel callbacks until the daemon
+	 * has registered.
+	 */
+	vss_transaction.active = true;
+	return 0;
+}
+
+void hv_vss_deinit(void)
+{
+	cn_del_callback(&vss_id);
+	cancel_delayed_work_sync(&vss_timeout_work);
+	cancel_work_sync(&vss_send_op_work);
+}
diff --git a/drivers/hv/hv_util.c b/drivers/hv/hv_util.c
new file mode 100644
index 000000000..7994ec2e4
--- /dev/null
+++ b/drivers/hv/hv_util.c
@@ -0,0 +1,447 @@
+/*
+ * Copyright (c) 2010, Microsoft Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
+ * Place - Suite 330, Boston, MA 02111-1307 USA.
+ *
+ * Authors:
+ *   Haiyang Zhang <haiyangz@microsoft.com>
+ *   Hank Janssen  <hjanssen@microsoft.com>
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/sysctl.h>
+#include <linux/reboot.h>
+#include <linux/hyperv.h>
+
+#include "hyperv_vmbus.h"
+
+#define SD_MAJOR	3
+#define SD_MINOR	0
+#define SD_VERSION	(SD_MAJOR << 16 | SD_MINOR)
+
+#define SD_WS2008_MAJOR		1
+#define SD_WS2008_VERSION	(SD_WS2008_MAJOR << 16 | SD_MINOR)
+
+#define TS_MAJOR	3
+#define TS_MINOR	0
+#define TS_VERSION	(TS_MAJOR << 16 | TS_MINOR)
+
+#define TS_WS2008_MAJOR		1
+#define TS_WS2008_VERSION	(TS_WS2008_MAJOR << 16 | TS_MINOR)
+
+#define HB_MAJOR	3
+#define HB_MINOR 0
+#define HB_VERSION	(HB_MAJOR << 16 | HB_MINOR)
+
+#define HB_WS2008_MAJOR	1
+#define HB_WS2008_VERSION	(HB_WS2008_MAJOR << 16 | HB_MINOR)
+
+static int sd_srv_version;
+static int ts_srv_version;
+static int hb_srv_version;
+static int util_fw_version;
+
+static void shutdown_onchannelcallback(void *context);
+static struct hv_util_service util_shutdown = {
+	.util_cb = shutdown_onchannelcallback,
+};
+
+static void timesync_onchannelcallback(void *context);
+static struct hv_util_service util_timesynch = {
+	.util_cb = timesync_onchannelcallback,
+};
+
+static void heartbeat_onchannelcallback(void *context);
+static struct hv_util_service util_heartbeat = {
+	.util_cb = heartbeat_onchannelcallback,
+};
+
+static struct hv_util_service util_kvp = {
+	.util_cb = hv_kvp_onchannelcallback,
+	.util_init = hv_kvp_init,
+	.util_deinit = hv_kvp_deinit,
+};
+
+static struct hv_util_service util_vss = {
+	.util_cb = hv_vss_onchannelcallback,
+	.util_init = hv_vss_init,
+	.util_deinit = hv_vss_deinit,
+};
+
+static struct hv_util_service util_fcopy = {
+	.util_cb = hv_fcopy_onchannelcallback,
+	.util_init = hv_fcopy_init,
+	.util_deinit = hv_fcopy_deinit,
+};
+
+static void perform_shutdown(struct work_struct *dummy)
+{
+	orderly_poweroff(true);
+}
+
+/*
+ * Perform the shutdown operation in a thread context.
+ */
+static DECLARE_WORK(shutdown_work, perform_shutdown);
+
+static void shutdown_onchannelcallback(void *context)
+{
+	struct vmbus_channel *channel = context;
+	u32 recvlen;
+	u64 requestid;
+	bool execute_shutdown = false;
+	u8  *shut_txf_buf = util_shutdown.recv_buffer;
+
+	struct shutdown_msg_data *shutdown_msg;
+
+	struct icmsg_hdr *icmsghdrp;
+	struct icmsg_negotiate *negop = NULL;
+
+	vmbus_recvpacket(channel, shut_txf_buf,
+			 PAGE_SIZE, &recvlen, &requestid);
+
+	if (recvlen > 0) {
+		icmsghdrp = (struct icmsg_hdr *)&shut_txf_buf[
+			sizeof(struct vmbuspipe_hdr)];
+
+		if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
+			vmbus_prep_negotiate_resp(icmsghdrp, negop,
+					shut_txf_buf, util_fw_version,
+					sd_srv_version);
+		} else {
+			shutdown_msg =
+				(struct shutdown_msg_data *)&shut_txf_buf[
+					sizeof(struct vmbuspipe_hdr) +
+					sizeof(struct icmsg_hdr)];
+
+			switch (shutdown_msg->flags) {
+			case 0:
+			case 1:
+				icmsghdrp->status = HV_S_OK;
+				execute_shutdown = true;
+
+				pr_info("Shutdown request received -"
+					    " graceful shutdown initiated\n");
+				break;
+			default:
+				icmsghdrp->status = HV_E_FAIL;
+				execute_shutdown = false;
+
+				pr_info("Shutdown request received -"
+					    " Invalid request\n");
+				break;
+			}
+		}
+
+		icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
+			| ICMSGHDRFLAG_RESPONSE;
+
+		vmbus_sendpacket(channel, shut_txf_buf,
+				       recvlen, requestid,
+				       VM_PKT_DATA_INBAND, 0);
+	}
+
+	if (execute_shutdown == true)
+		schedule_work(&shutdown_work);
+}
+
+/*
+ * Set guest time to host UTC time.
+ */
+static inline void do_adj_guesttime(u64 hosttime)
+{
+	s64 host_tns;
+	struct timespec host_ts;
+
+	host_tns = (hosttime - WLTIMEDELTA) * 100;
+	host_ts = ns_to_timespec(host_tns);
+
+	do_settimeofday(&host_ts);
+}
+
+/*
+ * Set the host time in a process context.
+ */
+
+struct adj_time_work {
+	struct work_struct work;
+	u64	host_time;
+};
+
+static void hv_set_host_time(struct work_struct *work)
+{
+	struct adj_time_work	*wrk;
+
+	wrk = container_of(work, struct adj_time_work, work);
+	do_adj_guesttime(wrk->host_time);
+	kfree(wrk);
+}
+
+/*
+ * Synchronize time with host after reboot, restore, etc.
+ *
+ * ICTIMESYNCFLAG_SYNC flag bit indicates reboot, restore events of the VM.
+ * After reboot the flag ICTIMESYNCFLAG_SYNC is included in the first time
+ * message after the timesync channel is opened. Since the hv_utils module is
+ * loaded after hv_vmbus, the first message is usually missed. The other
+ * thing is, systime is automatically set to emulated hardware clock which may
+ * not be UTC time or in the same time zone. So, to override these effects, we
+ * use the first 50 time samples for initial system time setting.
+ */
+static inline void adj_guesttime(u64 hosttime, u8 flags)
+{
+	struct adj_time_work    *wrk;
+	static s32 scnt = 50;
+
+	wrk = kmalloc(sizeof(struct adj_time_work), GFP_ATOMIC);
+	if (wrk == NULL)
+		return;
+
+	wrk->host_time = hosttime;
+	if ((flags & ICTIMESYNCFLAG_SYNC) != 0) {
+		INIT_WORK(&wrk->work, hv_set_host_time);
+		schedule_work(&wrk->work);
+		return;
+	}
+
+	if ((flags & ICTIMESYNCFLAG_SAMPLE) != 0 && scnt > 0) {
+		scnt--;
+		INIT_WORK(&wrk->work, hv_set_host_time);
+		schedule_work(&wrk->work);
+	} else
+		kfree(wrk);
+}
+
+/*
+ * Time Sync Channel message handler.
+ */
+static void timesync_onchannelcallback(void *context)
+{
+	struct vmbus_channel *channel = context;
+	u32 recvlen;
+	u64 requestid;
+	struct icmsg_hdr *icmsghdrp;
+	struct ictimesync_data *timedatap;
+	u8 *time_txf_buf = util_timesynch.recv_buffer;
+	struct icmsg_negotiate *negop = NULL;
+
+	vmbus_recvpacket(channel, time_txf_buf,
+			 PAGE_SIZE, &recvlen, &requestid);
+
+	if (recvlen > 0) {
+		icmsghdrp = (struct icmsg_hdr *)&time_txf_buf[
+				sizeof(struct vmbuspipe_hdr)];
+
+		if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
+			vmbus_prep_negotiate_resp(icmsghdrp, negop,
+						time_txf_buf,
+						util_fw_version,
+						ts_srv_version);
+		} else {
+			timedatap = (struct ictimesync_data *)&time_txf_buf[
+				sizeof(struct vmbuspipe_hdr) +
+				sizeof(struct icmsg_hdr)];
+			adj_guesttime(timedatap->parenttime, timedatap->flags);
+		}
+
+		icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
+			| ICMSGHDRFLAG_RESPONSE;
+
+		vmbus_sendpacket(channel, time_txf_buf,
+				recvlen, requestid,
+				VM_PKT_DATA_INBAND, 0);
+	}
+}
+
+/*
+ * Heartbeat functionality.
+ * Every two seconds, Hyper-V send us a heartbeat request message.
+ * we respond to this message, and Hyper-V knows we are alive.
+ */
+static void heartbeat_onchannelcallback(void *context)
+{
+	struct vmbus_channel *channel = context;
+	u32 recvlen;
+	u64 requestid;
+	struct icmsg_hdr *icmsghdrp;
+	struct heartbeat_msg_data *heartbeat_msg;
+	u8 *hbeat_txf_buf = util_heartbeat.recv_buffer;
+	struct icmsg_negotiate *negop = NULL;
+
+	vmbus_recvpacket(channel, hbeat_txf_buf,
+			 PAGE_SIZE, &recvlen, &requestid);
+
+	if (recvlen > 0) {
+		icmsghdrp = (struct icmsg_hdr *)&hbeat_txf_buf[
+				sizeof(struct vmbuspipe_hdr)];
+
+		if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
+			vmbus_prep_negotiate_resp(icmsghdrp, negop,
+				hbeat_txf_buf, util_fw_version,
+				hb_srv_version);
+		} else {
+			heartbeat_msg =
+				(struct heartbeat_msg_data *)&hbeat_txf_buf[
+					sizeof(struct vmbuspipe_hdr) +
+					sizeof(struct icmsg_hdr)];
+
+			heartbeat_msg->seq_num += 1;
+		}
+
+		icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
+			| ICMSGHDRFLAG_RESPONSE;
+
+		vmbus_sendpacket(channel, hbeat_txf_buf,
+				       recvlen, requestid,
+				       VM_PKT_DATA_INBAND, 0);
+	}
+}
+
+static int util_probe(struct hv_device *dev,
+			const struct hv_vmbus_device_id *dev_id)
+{
+	struct hv_util_service *srv =
+		(struct hv_util_service *)dev_id->driver_data;
+	int ret;
+
+	srv->recv_buffer = kmalloc(PAGE_SIZE * 4, GFP_KERNEL);
+	if (!srv->recv_buffer)
+		return -ENOMEM;
+	if (srv->util_init) {
+		ret = srv->util_init(srv);
+		if (ret) {
+			ret = -ENODEV;
+			goto error1;
+		}
+	}
+
+	/*
+	 * The set of services managed by the util driver are not performance
+	 * critical and do not need batched reading. Furthermore, some services
+	 * such as KVP can only handle one message from the host at a time.
+	 * Turn off batched reading for all util drivers before we open the
+	 * channel.
+	 */
+
+	set_channel_read_state(dev->channel, false);
+
+	hv_set_drvdata(dev, srv);
+
+	/*
+	 * Based on the host; initialize the framework and
+	 * service version numbers we will negotiate.
+	 */
+	switch (vmbus_proto_version) {
+	case (VERSION_WS2008):
+		util_fw_version = UTIL_WS2K8_FW_VERSION;
+		sd_srv_version = SD_WS2008_VERSION;
+		ts_srv_version = TS_WS2008_VERSION;
+		hb_srv_version = HB_WS2008_VERSION;
+		break;
+
+	default:
+		util_fw_version = UTIL_FW_VERSION;
+		sd_srv_version = SD_VERSION;
+		ts_srv_version = TS_VERSION;
+		hb_srv_version = HB_VERSION;
+	}
+
+	ret = vmbus_open(dev->channel, 4 * PAGE_SIZE, 4 * PAGE_SIZE, NULL, 0,
+			srv->util_cb, dev->channel);
+	if (ret)
+		goto error;
+
+	return 0;
+
+error:
+	if (srv->util_deinit)
+		srv->util_deinit();
+error1:
+	kfree(srv->recv_buffer);
+	return ret;
+}
+
+static int util_remove(struct hv_device *dev)
+{
+	struct hv_util_service *srv = hv_get_drvdata(dev);
+
+	if (srv->util_deinit)
+		srv->util_deinit();
+	vmbus_close(dev->channel);
+	kfree(srv->recv_buffer);
+
+	return 0;
+}
+
+static const struct hv_vmbus_device_id id_table[] = {
+	/* Shutdown guid */
+	{ HV_SHUTDOWN_GUID,
+	  .driver_data = (unsigned long)&util_shutdown
+	},
+	/* Time synch guid */
+	{ HV_TS_GUID,
+	  .driver_data = (unsigned long)&util_timesynch
+	},
+	/* Heartbeat guid */
+	{ HV_HEART_BEAT_GUID,
+	  .driver_data = (unsigned long)&util_heartbeat
+	},
+	/* KVP guid */
+	{ HV_KVP_GUID,
+	  .driver_data = (unsigned long)&util_kvp
+	},
+	/* VSS GUID */
+	{ HV_VSS_GUID,
+	  .driver_data = (unsigned long)&util_vss
+	},
+	/* File copy GUID */
+	{ HV_FCOPY_GUID,
+	  .driver_data = (unsigned long)&util_fcopy
+	},
+	{ },
+};
+
+MODULE_DEVICE_TABLE(vmbus, id_table);
+
+/* The one and only one */
+static  struct hv_driver util_drv = {
+	.name = "hv_util",
+	.id_table = id_table,
+	.probe =  util_probe,
+	.remove =  util_remove,
+};
+
+static int __init init_hyperv_utils(void)
+{
+	pr_info("Registering HyperV Utility Driver\n");
+
+	return vmbus_driver_register(&util_drv);
+}
+
+static void exit_hyperv_utils(void)
+{
+	pr_info("De-Registered HyperV Utility Driver\n");
+
+	vmbus_driver_unregister(&util_drv);
+}
+
+module_init(init_hyperv_utils);
+module_exit(exit_hyperv_utils);
+
+MODULE_DESCRIPTION("Hyper-V Utilities");
+MODULE_LICENSE("GPL");
diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
new file mode 100644
index 000000000..887287ad4
--- /dev/null
+++ b/drivers/hv/hyperv_vmbus.h
@@ -0,0 +1,738 @@
+/*
+ *
+ * Copyright (c) 2011, Microsoft Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
+ * Place - Suite 330, Boston, MA 02111-1307 USA.
+ *
+ * Authors:
+ *   Haiyang Zhang <haiyangz@microsoft.com>
+ *   Hank Janssen  <hjanssen@microsoft.com>
+ *   K. Y. Srinivasan <kys@microsoft.com>
+ *
+ */
+
+#ifndef _HYPERV_VMBUS_H
+#define _HYPERV_VMBUS_H
+
+#include <linux/list.h>
+#include <asm/sync_bitops.h>
+#include <linux/atomic.h>
+#include <linux/hyperv.h>
+
+/*
+ * The below CPUID leaves are present if VersionAndFeatures.HypervisorPresent
+ * is set by CPUID(HVCPUID_VERSION_FEATURES).
+ */
+enum hv_cpuid_function {
+	HVCPUID_VERSION_FEATURES		= 0x00000001,
+	HVCPUID_VENDOR_MAXFUNCTION		= 0x40000000,
+	HVCPUID_INTERFACE			= 0x40000001,
+
+	/*
+	 * The remaining functions depend on the value of
+	 * HVCPUID_INTERFACE
+	 */
+	HVCPUID_VERSION			= 0x40000002,
+	HVCPUID_FEATURES			= 0x40000003,
+	HVCPUID_ENLIGHTENMENT_INFO	= 0x40000004,
+	HVCPUID_IMPLEMENTATION_LIMITS		= 0x40000005,
+};
+
+#define  HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE   0x400
+
+#define HV_X64_MSR_CRASH_P0   0x40000100
+#define HV_X64_MSR_CRASH_P1   0x40000101
+#define HV_X64_MSR_CRASH_P2   0x40000102
+#define HV_X64_MSR_CRASH_P3   0x40000103
+#define HV_X64_MSR_CRASH_P4   0x40000104
+#define HV_X64_MSR_CRASH_CTL  0x40000105
+
+#define HV_CRASH_CTL_CRASH_NOTIFY (1ULL << 63)
+
+/* Define version of the synthetic interrupt controller. */
+#define HV_SYNIC_VERSION		(1)
+
+/* Define the expected SynIC version. */
+#define HV_SYNIC_VERSION_1		(0x1)
+
+/* Define synthetic interrupt controller message constants. */
+#define HV_MESSAGE_SIZE			(256)
+#define HV_MESSAGE_PAYLOAD_BYTE_COUNT	(240)
+#define HV_MESSAGE_PAYLOAD_QWORD_COUNT	(30)
+#define HV_ANY_VP			(0xFFFFFFFF)
+
+/* Define synthetic interrupt controller flag constants. */
+#define HV_EVENT_FLAGS_COUNT		(256 * 8)
+#define HV_EVENT_FLAGS_BYTE_COUNT	(256)
+#define HV_EVENT_FLAGS_DWORD_COUNT	(256 / sizeof(u32))
+
+/* Define hypervisor message types. */
+enum hv_message_type {
+	HVMSG_NONE			= 0x00000000,
+
+	/* Memory access messages. */
+	HVMSG_UNMAPPED_GPA		= 0x80000000,
+	HVMSG_GPA_INTERCEPT		= 0x80000001,
+
+	/* Timer notification messages. */
+	HVMSG_TIMER_EXPIRED			= 0x80000010,
+
+	/* Error messages. */
+	HVMSG_INVALID_VP_REGISTER_VALUE	= 0x80000020,
+	HVMSG_UNRECOVERABLE_EXCEPTION	= 0x80000021,
+	HVMSG_UNSUPPORTED_FEATURE		= 0x80000022,
+
+	/* Trace buffer complete messages. */
+	HVMSG_EVENTLOG_BUFFERCOMPLETE	= 0x80000040,
+
+	/* Platform-specific processor intercept messages. */
+	HVMSG_X64_IOPORT_INTERCEPT		= 0x80010000,
+	HVMSG_X64_MSR_INTERCEPT		= 0x80010001,
+	HVMSG_X64_CPUID_INTERCEPT		= 0x80010002,
+	HVMSG_X64_EXCEPTION_INTERCEPT	= 0x80010003,
+	HVMSG_X64_APIC_EOI			= 0x80010004,
+	HVMSG_X64_LEGACY_FP_ERROR		= 0x80010005
+};
+
+/* Define the number of synthetic interrupt sources. */
+#define HV_SYNIC_SINT_COUNT		(16)
+#define HV_SYNIC_STIMER_COUNT		(4)
+
+/* Define invalid partition identifier. */
+#define HV_PARTITION_ID_INVALID		((u64)0x0)
+
+/* Define port identifier type. */
+union hv_port_id {
+	u32 asu32;
+	struct {
+		u32 id:24;
+		u32 reserved:8;
+	} u ;
+};
+
+/* Define port type. */
+enum hv_port_type {
+	HVPORT_MSG	= 1,
+	HVPORT_EVENT		= 2,
+	HVPORT_MONITOR	= 3
+};
+
+/* Define port information structure. */
+struct hv_port_info {
+	enum hv_port_type port_type;
+	u32 padding;
+	union {
+		struct {
+			u32 target_sint;
+			u32 target_vp;
+			u64 rsvdz;
+		} message_port_info;
+		struct {
+			u32 target_sint;
+			u32 target_vp;
+			u16 base_flag_bumber;
+			u16 flag_count;
+			u32 rsvdz;
+		} event_port_info;
+		struct {
+			u64 monitor_address;
+			u64 rsvdz;
+		} monitor_port_info;
+	};
+};
+
+struct hv_connection_info {
+	enum hv_port_type port_type;
+	u32 padding;
+	union {
+		struct {
+			u64 rsvdz;
+		} message_connection_info;
+		struct {
+			u64 rsvdz;
+		} event_connection_info;
+		struct {
+			u64 monitor_address;
+		} monitor_connection_info;
+	};
+};
+
+/* Define synthetic interrupt controller message flags. */
+union hv_message_flags {
+	u8 asu8;
+	struct {
+		u8 msg_pending:1;
+		u8 reserved:7;
+	};
+};
+
+/* Define synthetic interrupt controller message header. */
+struct hv_message_header {
+	enum hv_message_type message_type;
+	u8 payload_size;
+	union hv_message_flags message_flags;
+	u8 reserved[2];
+	union {
+		u64 sender;
+		union hv_port_id port;
+	};
+};
+
+/*
+ * Timer configuration register.
+ */
+union hv_timer_config {
+	u64 as_uint64;
+	struct {
+		u64 enable:1;
+		u64 periodic:1;
+		u64 lazy:1;
+		u64 auto_enable:1;
+		u64 reserved_z0:12;
+		u64 sintx:4;
+		u64 reserved_z1:44;
+	};
+};
+
+
+/* Define timer message payload structure. */
+struct hv_timer_message_payload {
+	u32 timer_index;
+	u32 reserved;
+	u64 expiration_time;	/* When the timer expired */
+	u64 delivery_time;	/* When the message was delivered */
+};
+
+/* Define synthetic interrupt controller message format. */
+struct hv_message {
+	struct hv_message_header header;
+	union {
+		u64 payload[HV_MESSAGE_PAYLOAD_QWORD_COUNT];
+	} u ;
+};
+
+/* Define the number of message buffers associated with each port. */
+#define HV_PORT_MESSAGE_BUFFER_COUNT	(16)
+
+/* Define the synthetic interrupt message page layout. */
+struct hv_message_page {
+	struct hv_message sint_message[HV_SYNIC_SINT_COUNT];
+};
+
+/* Define the synthetic interrupt controller event flags format. */
+union hv_synic_event_flags {
+	u8 flags8[HV_EVENT_FLAGS_BYTE_COUNT];
+	u32 flags32[HV_EVENT_FLAGS_DWORD_COUNT];
+};
+
+/* Define the synthetic interrupt flags page layout. */
+struct hv_synic_event_flags_page {
+	union hv_synic_event_flags sintevent_flags[HV_SYNIC_SINT_COUNT];
+};
+
+/* Define SynIC control register. */
+union hv_synic_scontrol {
+	u64 as_uint64;
+	struct {
+		u64 enable:1;
+		u64 reserved:63;
+	};
+};
+
+/* Define synthetic interrupt source. */
+union hv_synic_sint {
+	u64 as_uint64;
+	struct {
+		u64 vector:8;
+		u64 reserved1:8;
+		u64 masked:1;
+		u64 auto_eoi:1;
+		u64 reserved2:46;
+	};
+};
+
+/* Define the format of the SIMP register */
+union hv_synic_simp {
+	u64 as_uint64;
+	struct {
+		u64 simp_enabled:1;
+		u64 preserved:11;
+		u64 base_simp_gpa:52;
+	};
+};
+
+/* Define the format of the SIEFP register */
+union hv_synic_siefp {
+	u64 as_uint64;
+	struct {
+		u64 siefp_enabled:1;
+		u64 preserved:11;
+		u64 base_siefp_gpa:52;
+	};
+};
+
+/* Definitions for the monitored notification facility */
+union hv_monitor_trigger_group {
+	u64 as_uint64;
+	struct {
+		u32 pending;
+		u32 armed;
+	};
+};
+
+struct hv_monitor_parameter {
+	union hv_connection_id connectionid;
+	u16 flagnumber;
+	u16 rsvdz;
+};
+
+union hv_monitor_trigger_state {
+	u32 asu32;
+
+	struct {
+		u32 group_enable:4;
+		u32 rsvdz:28;
+	};
+};
+
+/* struct hv_monitor_page Layout */
+/* ------------------------------------------------------ */
+/* | 0   | TriggerState (4 bytes) | Rsvd1 (4 bytes)     | */
+/* | 8   | TriggerGroup[0]                              | */
+/* | 10  | TriggerGroup[1]                              | */
+/* | 18  | TriggerGroup[2]                              | */
+/* | 20  | TriggerGroup[3]                              | */
+/* | 28  | Rsvd2[0]                                     | */
+/* | 30  | Rsvd2[1]                                     | */
+/* | 38  | Rsvd2[2]                                     | */
+/* | 40  | NextCheckTime[0][0]    | NextCheckTime[0][1] | */
+/* | ...                                                | */
+/* | 240 | Latency[0][0..3]                             | */
+/* | 340 | Rsvz3[0]                                     | */
+/* | 440 | Parameter[0][0]                              | */
+/* | 448 | Parameter[0][1]                              | */
+/* | ...                                                | */
+/* | 840 | Rsvd4[0]                                     | */
+/* ------------------------------------------------------ */
+struct hv_monitor_page {
+	union hv_monitor_trigger_state trigger_state;
+	u32 rsvdz1;
+
+	union hv_monitor_trigger_group trigger_group[4];
+	u64 rsvdz2[3];
+
+	s32 next_checktime[4][32];
+
+	u16 latency[4][32];
+	u64 rsvdz3[32];
+
+	struct hv_monitor_parameter parameter[4][32];
+
+	u8 rsvdz4[1984];
+};
+
+/* Declare the various hypercall operations. */
+enum hv_call_code {
+	HVCALL_POST_MESSAGE	= 0x005c,
+	HVCALL_SIGNAL_EVENT	= 0x005d,
+};
+
+/* Definition of the hv_post_message hypercall input structure. */
+struct hv_input_post_message {
+	union hv_connection_id connectionid;
+	u32 reserved;
+	enum hv_message_type message_type;
+	u32 payload_size;
+	u64 payload[HV_MESSAGE_PAYLOAD_QWORD_COUNT];
+};
+
+/*
+ * Versioning definitions used for guests reporting themselves to the
+ * hypervisor, and visa versa.
+ */
+
+/* Version info reported by guest OS's */
+enum hv_guest_os_vendor {
+	HVGUESTOS_VENDOR_MICROSOFT	= 0x0001
+};
+
+enum hv_guest_os_microsoft_ids {
+	HVGUESTOS_MICROSOFT_UNDEFINED	= 0x00,
+	HVGUESTOS_MICROSOFT_MSDOS		= 0x01,
+	HVGUESTOS_MICROSOFT_WINDOWS3X	= 0x02,
+	HVGUESTOS_MICROSOFT_WINDOWS9X	= 0x03,
+	HVGUESTOS_MICROSOFT_WINDOWSNT	= 0x04,
+	HVGUESTOS_MICROSOFT_WINDOWSCE	= 0x05
+};
+
+/*
+ * Declare the MSR used to identify the guest OS.
+ */
+#define HV_X64_MSR_GUEST_OS_ID	0x40000000
+
+union hv_x64_msr_guest_os_id_contents {
+	u64 as_uint64;
+	struct {
+		u64 build_number:16;
+		u64 service_version:8; /* Service Pack, etc. */
+		u64 minor_version:8;
+		u64 major_version:8;
+		u64 os_id:8; /* enum hv_guest_os_microsoft_ids (if Vendor=MS) */
+		u64 vendor_id:16; /* enum hv_guest_os_vendor */
+	};
+};
+
+/*
+ * Declare the MSR used to setup pages used to communicate with the hypervisor.
+ */
+#define HV_X64_MSR_HYPERCALL	0x40000001
+
+union hv_x64_msr_hypercall_contents {
+	u64 as_uint64;
+	struct {
+		u64 enable:1;
+		u64 reserved:11;
+		u64 guest_physical_address:52;
+	};
+};
+
+
+enum {
+	VMBUS_MESSAGE_CONNECTION_ID	= 1,
+	VMBUS_MESSAGE_PORT_ID		= 1,
+	VMBUS_EVENT_CONNECTION_ID	= 2,
+	VMBUS_EVENT_PORT_ID		= 2,
+	VMBUS_MONITOR_CONNECTION_ID	= 3,
+	VMBUS_MONITOR_PORT_ID		= 3,
+	VMBUS_MESSAGE_SINT		= 2,
+};
+
+/* #defines */
+
+#define HV_PRESENT_BIT			0x80000000
+
+/*
+ * The guest OS needs to register the guest ID with the hypervisor.
+ * The guest ID is a 64 bit entity and the structure of this ID is
+ * specified in the Hyper-V specification:
+ *
+ * http://msdn.microsoft.com/en-us/library/windows/hardware/ff542653%28v=vs.85%29.aspx
+ *
+ * While the current guideline does not specify how Linux guest ID(s)
+ * need to be generated, our plan is to publish the guidelines for
+ * Linux and other guest operating systems that currently are hosted
+ * on Hyper-V. The implementation here conforms to this yet
+ * unpublished guidelines.
+ *
+ *
+ * Bit(s)
+ * 63 - Indicates if the OS is Open Source or not; 1 is Open Source
+ * 62:56 - Os Type; Linux is 0x100
+ * 55:48 - Distro specific identification
+ * 47:16 - Linux kernel version number
+ * 15:0  - Distro specific identification
+ *
+ *
+ */
+
+#define HV_LINUX_VENDOR_ID		0x8100
+
+/*
+ * Generate the guest ID based on the guideline described above.
+ */
+
+static inline  __u64 generate_guest_id(__u8 d_info1, __u32 kernel_version,
+					__u16 d_info2)
+{
+	__u64 guest_id = 0;
+
+	guest_id = (((__u64)HV_LINUX_VENDOR_ID) << 48);
+	guest_id |= (((__u64)(d_info1)) << 48);
+	guest_id |= (((__u64)(kernel_version)) << 16);
+	guest_id |= ((__u64)(d_info2));
+
+	return guest_id;
+}
+
+
+#define HV_CPU_POWER_MANAGEMENT		(1 << 0)
+#define HV_RECOMMENDATIONS_MAX		4
+
+#define HV_X64_MAX			5
+#define HV_CAPS_MAX			8
+
+
+#define HV_HYPERCALL_PARAM_ALIGN	sizeof(u64)
+
+
+/* Service definitions */
+
+#define HV_SERVICE_PARENT_PORT				(0)
+#define HV_SERVICE_PARENT_CONNECTION			(0)
+
+#define HV_SERVICE_CONNECT_RESPONSE_SUCCESS		(0)
+#define HV_SERVICE_CONNECT_RESPONSE_INVALID_PARAMETER	(1)
+#define HV_SERVICE_CONNECT_RESPONSE_UNKNOWN_SERVICE	(2)
+#define HV_SERVICE_CONNECT_RESPONSE_CONNECTION_REJECTED	(3)
+
+#define HV_SERVICE_CONNECT_REQUEST_MESSAGE_ID		(1)
+#define HV_SERVICE_CONNECT_RESPONSE_MESSAGE_ID		(2)
+#define HV_SERVICE_DISCONNECT_REQUEST_MESSAGE_ID	(3)
+#define HV_SERVICE_DISCONNECT_RESPONSE_MESSAGE_ID	(4)
+#define HV_SERVICE_MAX_MESSAGE_ID				(4)
+
+#define HV_SERVICE_PROTOCOL_VERSION (0x0010)
+#define HV_CONNECT_PAYLOAD_BYTE_COUNT 64
+
+/* #define VMBUS_REVISION_NUMBER	6 */
+
+/* Our local vmbus's port and connection id. Anything >0 is fine */
+/* #define VMBUS_PORT_ID		11 */
+
+/* 628180B8-308D-4c5e-B7DB-1BEB62E62EF4 */
+static const uuid_le VMBUS_SERVICE_ID = {
+	.b = {
+		0xb8, 0x80, 0x81, 0x62, 0x8d, 0x30, 0x5e, 0x4c,
+		0xb7, 0xdb, 0x1b, 0xeb, 0x62, 0xe6, 0x2e, 0xf4
+	},
+};
+
+
+
+struct hv_context {
+	/* We only support running on top of Hyper-V
+	* So at this point this really can only contain the Hyper-V ID
+	*/
+	u64 guestid;
+
+	void *hypercall_page;
+
+	bool synic_initialized;
+
+	void *synic_message_page[NR_CPUS];
+	void *synic_event_page[NR_CPUS];
+	/*
+	 * Hypervisor's notion of virtual processor ID is different from
+	 * Linux' notion of CPU ID. This information can only be retrieved
+	 * in the context of the calling CPU. Setup a map for easy access
+	 * to this information:
+	 *
+	 * vp_index[a] is the Hyper-V's processor ID corresponding to
+	 * Linux cpuid 'a'.
+	 */
+	u32 vp_index[NR_CPUS];
+	/*
+	 * Starting with win8, we can take channel interrupts on any CPU;
+	 * we will manage the tasklet that handles events on a per CPU
+	 * basis.
+	 */
+	struct tasklet_struct *event_dpc[NR_CPUS];
+	/*
+	 * To optimize the mapping of relid to channel, maintain
+	 * per-cpu list of the channels based on their CPU affinity.
+	 */
+	struct list_head percpu_list[NR_CPUS];
+	/*
+	 * buffer to post messages to the host.
+	 */
+	void *post_msg_page[NR_CPUS];
+	/*
+	 * Support PV clockevent device.
+	 */
+	struct clock_event_device *clk_evt[NR_CPUS];
+};
+
+extern struct hv_context hv_context;
+
+struct hv_ring_buffer_debug_info {
+	u32 current_interrupt_mask;
+	u32 current_read_index;
+	u32 current_write_index;
+	u32 bytes_avail_toread;
+	u32 bytes_avail_towrite;
+};
+
+/* Hv Interface */
+
+extern int hv_init(void);
+
+extern void hv_cleanup(void);
+
+extern int hv_post_message(union hv_connection_id connection_id,
+			 enum hv_message_type message_type,
+			 void *payload, size_t payload_size);
+
+extern u16 hv_signal_event(void *con_id);
+
+extern int hv_synic_alloc(void);
+
+extern void hv_synic_free(void);
+
+extern void hv_synic_init(void *irqarg);
+
+extern void hv_synic_cleanup(void *arg);
+
+extern void hv_synic_clockevents_cleanup(void);
+
+/*
+ * Host version information.
+ */
+extern unsigned int host_info_eax;
+extern unsigned int host_info_ebx;
+extern unsigned int host_info_ecx;
+extern unsigned int host_info_edx;
+
+/* Interface */
+
+
+int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info, void *buffer,
+		   u32 buflen);
+
+void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info);
+
+int hv_ringbuffer_write(struct hv_ring_buffer_info *ring_info,
+		    struct kvec *kv_list,
+		    u32 kv_count, bool *signal);
+
+int hv_ringbuffer_peek(struct hv_ring_buffer_info *ring_info, void *buffer,
+		   u32 buflen);
+
+int hv_ringbuffer_read(struct hv_ring_buffer_info *ring_info,
+		   void *buffer,
+		   u32 buflen,
+		   u32 offset, bool *signal);
+
+
+void hv_ringbuffer_get_debuginfo(struct hv_ring_buffer_info *ring_info,
+			    struct hv_ring_buffer_debug_info *debug_info);
+
+void hv_begin_read(struct hv_ring_buffer_info *rbi);
+
+u32 hv_end_read(struct hv_ring_buffer_info *rbi);
+
+/*
+ * Maximum channels is determined by the size of the interrupt page
+ * which is PAGE_SIZE. 1/2 of PAGE_SIZE is for send endpoint interrupt
+ * and the other is receive endpoint interrupt
+ */
+#define MAX_NUM_CHANNELS	((PAGE_SIZE >> 1) << 3)	/* 16348 channels */
+
+/* The value here must be in multiple of 32 */
+/* TODO: Need to make this configurable */
+#define MAX_NUM_CHANNELS_SUPPORTED	256
+
+
+enum vmbus_connect_state {
+	DISCONNECTED,
+	CONNECTING,
+	CONNECTED,
+	DISCONNECTING
+};
+
+#define MAX_SIZE_CHANNEL_MESSAGE	HV_MESSAGE_PAYLOAD_BYTE_COUNT
+
+struct vmbus_connection {
+	enum vmbus_connect_state conn_state;
+
+	atomic_t next_gpadl_handle;
+
+	/*
+	 * Represents channel interrupts. Each bit position represents a
+	 * channel.  When a channel sends an interrupt via VMBUS, it finds its
+	 * bit in the sendInterruptPage, set it and calls Hv to generate a port
+	 * event. The other end receives the port event and parse the
+	 * recvInterruptPage to see which bit is set
+	 */
+	void *int_page;
+	void *send_int_page;
+	void *recv_int_page;
+
+	/*
+	 * 2 pages - 1st page for parent->child notification and 2nd
+	 * is child->parent notification
+	 */
+	struct hv_monitor_page *monitor_pages[2];
+	struct list_head chn_msg_list;
+	spinlock_t channelmsg_lock;
+
+	/* List of channels */
+	struct list_head chn_list;
+	spinlock_t channel_lock;
+
+	struct workqueue_struct *work_queue;
+};
+
+
+struct vmbus_msginfo {
+	/* Bookkeeping stuff */
+	struct list_head msglist_entry;
+
+	/* The message itself */
+	unsigned char msg[0];
+};
+
+
+extern struct vmbus_connection vmbus_connection;
+
+enum vmbus_message_handler_type {
+	/* The related handler can sleep. */
+	VMHT_BLOCKING = 0,
+
+	/* The related handler must NOT sleep. */
+	VMHT_NON_BLOCKING = 1,
+};
+
+struct vmbus_channel_message_table_entry {
+	enum vmbus_channel_message_type message_type;
+	enum vmbus_message_handler_type handler_type;
+	void (*message_handler)(struct vmbus_channel_message_header *msg);
+};
+
+extern struct vmbus_channel_message_table_entry
+	channel_message_table[CHANNELMSG_COUNT];
+
+/* General vmbus interface */
+
+struct hv_device *vmbus_device_create(const uuid_le *type,
+				      const uuid_le *instance,
+				      struct vmbus_channel *channel);
+
+int vmbus_device_register(struct hv_device *child_device_obj);
+void vmbus_device_unregister(struct hv_device *device_obj);
+
+/* static void */
+/* VmbusChildDeviceDestroy( */
+/* struct hv_device *); */
+
+struct vmbus_channel *relid2channel(u32 relid);
+
+void vmbus_free_channels(void);
+
+/* Connection interface */
+
+int vmbus_connect(void);
+void vmbus_disconnect(void);
+
+int vmbus_post_msg(void *buffer, size_t buflen);
+
+int vmbus_set_event(struct vmbus_channel *channel);
+
+void vmbus_on_event(unsigned long data);
+
+int hv_fcopy_init(struct hv_util_service *);
+void hv_fcopy_deinit(void);
+void hv_fcopy_onchannelcallback(void *);
+
+
+#endif /* _HYPERV_VMBUS_H */
diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
new file mode 100644
index 000000000..6361d124f
--- /dev/null
+++ b/drivers/hv/ring_buffer.c
@@ -0,0 +1,566 @@
+/*
+ *
+ * Copyright (c) 2009, Microsoft Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
+ * Place - Suite 330, Boston, MA 02111-1307 USA.
+ *
+ * Authors:
+ *   Haiyang Zhang <haiyangz@microsoft.com>
+ *   Hank Janssen  <hjanssen@microsoft.com>
+ *   K. Y. Srinivasan <kys@microsoft.com>
+ *
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/hyperv.h>
+#include <linux/uio.h>
+
+#include "hyperv_vmbus.h"
+
+void hv_begin_read(struct hv_ring_buffer_info *rbi)
+{
+	rbi->ring_buffer->interrupt_mask = 1;
+	mb();
+}
+
+u32 hv_end_read(struct hv_ring_buffer_info *rbi)
+{
+	u32 read;
+	u32 write;
+
+	rbi->ring_buffer->interrupt_mask = 0;
+	mb();
+
+	/*
+	 * Now check to see if the ring buffer is still empty.
+	 * If it is not, we raced and we need to process new
+	 * incoming messages.
+	 */
+	hv_get_ringbuffer_availbytes(rbi, &read, &write);
+
+	return read;
+}
+
+/*
+ * When we write to the ring buffer, check if the host needs to
+ * be signaled. Here is the details of this protocol:
+ *
+ *	1. The host guarantees that while it is draining the
+ *	   ring buffer, it will set the interrupt_mask to
+ *	   indicate it does not need to be interrupted when
+ *	   new data is placed.
+ *
+ *	2. The host guarantees that it will completely drain
+ *	   the ring buffer before exiting the read loop. Further,
+ *	   once the ring buffer is empty, it will clear the
+ *	   interrupt_mask and re-check to see if new data has
+ *	   arrived.
+ */
+
+static bool hv_need_to_signal(u32 old_write, struct hv_ring_buffer_info *rbi)
+{
+	mb();
+	if (rbi->ring_buffer->interrupt_mask)
+		return false;
+
+	/* check interrupt_mask before read_index */
+	rmb();
+	/*
+	 * This is the only case we need to signal when the
+	 * ring transitions from being empty to non-empty.
+	 */
+	if (old_write == rbi->ring_buffer->read_index)
+		return true;
+
+	return false;
+}
+
+/*
+ * To optimize the flow management on the send-side,
+ * when the sender is blocked because of lack of
+ * sufficient space in the ring buffer, potential the
+ * consumer of the ring buffer can signal the producer.
+ * This is controlled by the following parameters:
+ *
+ * 1. pending_send_sz: This is the size in bytes that the
+ *    producer is trying to send.
+ * 2. The feature bit feat_pending_send_sz set to indicate if
+ *    the consumer of the ring will signal when the ring
+ *    state transitions from being full to a state where
+ *    there is room for the producer to send the pending packet.
+ */
+
+static bool hv_need_to_signal_on_read(u32 old_rd,
+					 struct hv_ring_buffer_info *rbi)
+{
+	u32 prev_write_sz;
+	u32 cur_write_sz;
+	u32 r_size;
+	u32 write_loc = rbi->ring_buffer->write_index;
+	u32 read_loc = rbi->ring_buffer->read_index;
+	u32 pending_sz = rbi->ring_buffer->pending_send_sz;
+
+	/*
+	 * If the other end is not blocked on write don't bother.
+	 */
+	if (pending_sz == 0)
+		return false;
+
+	r_size = rbi->ring_datasize;
+	cur_write_sz = write_loc >= read_loc ? r_size - (write_loc - read_loc) :
+			read_loc - write_loc;
+
+	prev_write_sz = write_loc >= old_rd ? r_size - (write_loc - old_rd) :
+			old_rd - write_loc;
+
+
+	if ((prev_write_sz < pending_sz) && (cur_write_sz >= pending_sz))
+		return true;
+
+	return false;
+}
+
+/*
+ * hv_get_next_write_location()
+ *
+ * Get the next write location for the specified ring buffer
+ *
+ */
+static inline u32
+hv_get_next_write_location(struct hv_ring_buffer_info *ring_info)
+{
+	u32 next = ring_info->ring_buffer->write_index;
+
+	return next;
+}
+
+/*
+ * hv_set_next_write_location()
+ *
+ * Set the next write location for the specified ring buffer
+ *
+ */
+static inline void
+hv_set_next_write_location(struct hv_ring_buffer_info *ring_info,
+		     u32 next_write_location)
+{
+	ring_info->ring_buffer->write_index = next_write_location;
+}
+
+/*
+ * hv_get_next_read_location()
+ *
+ * Get the next read location for the specified ring buffer
+ */
+static inline u32
+hv_get_next_read_location(struct hv_ring_buffer_info *ring_info)
+{
+	u32 next = ring_info->ring_buffer->read_index;
+
+	return next;
+}
+
+/*
+ * hv_get_next_readlocation_withoffset()
+ *
+ * Get the next read location + offset for the specified ring buffer.
+ * This allows the caller to skip
+ */
+static inline u32
+hv_get_next_readlocation_withoffset(struct hv_ring_buffer_info *ring_info,
+				 u32 offset)
+{
+	u32 next = ring_info->ring_buffer->read_index;
+
+	next += offset;
+	next %= ring_info->ring_datasize;
+
+	return next;
+}
+
+/*
+ *
+ * hv_set_next_read_location()
+ *
+ * Set the next read location for the specified ring buffer
+ *
+ */
+static inline void
+hv_set_next_read_location(struct hv_ring_buffer_info *ring_info,
+		    u32 next_read_location)
+{
+	ring_info->ring_buffer->read_index = next_read_location;
+}
+
+
+/*
+ *
+ * hv_get_ring_buffer()
+ *
+ * Get the start of the ring buffer
+ */
+static inline void *
+hv_get_ring_buffer(struct hv_ring_buffer_info *ring_info)
+{
+	return (void *)ring_info->ring_buffer->buffer;
+}
+
+
+/*
+ *
+ * hv_get_ring_buffersize()
+ *
+ * Get the size of the ring buffer
+ */
+static inline u32
+hv_get_ring_buffersize(struct hv_ring_buffer_info *ring_info)
+{
+	return ring_info->ring_datasize;
+}
+
+/*
+ *
+ * hv_get_ring_bufferindices()
+ *
+ * Get the read and write indices as u64 of the specified ring buffer
+ *
+ */
+static inline u64
+hv_get_ring_bufferindices(struct hv_ring_buffer_info *ring_info)
+{
+	return (u64)ring_info->ring_buffer->write_index << 32;
+}
+
+/*
+ *
+ * hv_copyfrom_ringbuffer()
+ *
+ * Helper routine to copy to source from ring buffer.
+ * Assume there is enough room. Handles wrap-around in src case only!!
+ *
+ */
+static u32 hv_copyfrom_ringbuffer(
+	struct hv_ring_buffer_info	*ring_info,
+	void				*dest,
+	u32				destlen,
+	u32				start_read_offset)
+{
+	void *ring_buffer = hv_get_ring_buffer(ring_info);
+	u32 ring_buffer_size = hv_get_ring_buffersize(ring_info);
+
+	u32 frag_len;
+
+	/* wrap-around detected at the src */
+	if (destlen > ring_buffer_size - start_read_offset) {
+		frag_len = ring_buffer_size - start_read_offset;
+
+		memcpy(dest, ring_buffer + start_read_offset, frag_len);
+		memcpy(dest + frag_len, ring_buffer, destlen - frag_len);
+	} else
+
+		memcpy(dest, ring_buffer + start_read_offset, destlen);
+
+
+	start_read_offset += destlen;
+	start_read_offset %= ring_buffer_size;
+
+	return start_read_offset;
+}
+
+
+/*
+ *
+ * hv_copyto_ringbuffer()
+ *
+ * Helper routine to copy from source to ring buffer.
+ * Assume there is enough room. Handles wrap-around in dest case only!!
+ *
+ */
+static u32 hv_copyto_ringbuffer(
+	struct hv_ring_buffer_info	*ring_info,
+	u32				start_write_offset,
+	void				*src,
+	u32				srclen)
+{
+	void *ring_buffer = hv_get_ring_buffer(ring_info);
+	u32 ring_buffer_size = hv_get_ring_buffersize(ring_info);
+	u32 frag_len;
+
+	/* wrap-around detected! */
+	if (srclen > ring_buffer_size - start_write_offset) {
+		frag_len = ring_buffer_size - start_write_offset;
+		memcpy(ring_buffer + start_write_offset, src, frag_len);
+		memcpy(ring_buffer, src + frag_len, srclen - frag_len);
+	} else
+		memcpy(ring_buffer + start_write_offset, src, srclen);
+
+	start_write_offset += srclen;
+	start_write_offset %= ring_buffer_size;
+
+	return start_write_offset;
+}
+
+/*
+ *
+ * hv_ringbuffer_get_debuginfo()
+ *
+ * Get various debug metrics for the specified ring buffer
+ *
+ */
+void hv_ringbuffer_get_debuginfo(struct hv_ring_buffer_info *ring_info,
+			    struct hv_ring_buffer_debug_info *debug_info)
+{
+	u32 bytes_avail_towrite;
+	u32 bytes_avail_toread;
+
+	if (ring_info->ring_buffer) {
+		hv_get_ringbuffer_availbytes(ring_info,
+					&bytes_avail_toread,
+					&bytes_avail_towrite);
+
+		debug_info->bytes_avail_toread = bytes_avail_toread;
+		debug_info->bytes_avail_towrite = bytes_avail_towrite;
+		debug_info->current_read_index =
+			ring_info->ring_buffer->read_index;
+		debug_info->current_write_index =
+			ring_info->ring_buffer->write_index;
+		debug_info->current_interrupt_mask =
+			ring_info->ring_buffer->interrupt_mask;
+	}
+}
+
+/*
+ *
+ * hv_ringbuffer_init()
+ *
+ *Initialize the ring buffer
+ *
+ */
+int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info,
+		   void *buffer, u32 buflen)
+{
+	if (sizeof(struct hv_ring_buffer) != PAGE_SIZE)
+		return -EINVAL;
+
+	memset(ring_info, 0, sizeof(struct hv_ring_buffer_info));
+
+	ring_info->ring_buffer = (struct hv_ring_buffer *)buffer;
+	ring_info->ring_buffer->read_index =
+		ring_info->ring_buffer->write_index = 0;
+
+	/*
+	 * Set the feature bit for enabling flow control.
+	 */
+	ring_info->ring_buffer->feature_bits.value = 1;
+
+	ring_info->ring_size = buflen;
+	ring_info->ring_datasize = buflen - sizeof(struct hv_ring_buffer);
+
+	spin_lock_init(&ring_info->ring_lock);
+
+	return 0;
+}
+
+/*
+ *
+ * hv_ringbuffer_cleanup()
+ *
+ * Cleanup the ring buffer
+ *
+ */
+void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info)
+{
+}
+
+/*
+ *
+ * hv_ringbuffer_write()
+ *
+ * Write to the ring buffer
+ *
+ */
+int hv_ringbuffer_write(struct hv_ring_buffer_info *outring_info,
+		    struct kvec *kv_list, u32 kv_count, bool *signal)
+{
+	int i = 0;
+	u32 bytes_avail_towrite;
+	u32 bytes_avail_toread;
+	u32 totalbytes_towrite = 0;
+
+	u32 next_write_location;
+	u32 old_write;
+	u64 prev_indices = 0;
+	unsigned long flags;
+
+	for (i = 0; i < kv_count; i++)
+		totalbytes_towrite += kv_list[i].iov_len;
+
+	totalbytes_towrite += sizeof(u64);
+
+	spin_lock_irqsave(&outring_info->ring_lock, flags);
+
+	hv_get_ringbuffer_availbytes(outring_info,
+				&bytes_avail_toread,
+				&bytes_avail_towrite);
+
+
+	/* If there is only room for the packet, assume it is full. */
+	/* Otherwise, the next time around, we think the ring buffer */
+	/* is empty since the read index == write index */
+	if (bytes_avail_towrite <= totalbytes_towrite) {
+		spin_unlock_irqrestore(&outring_info->ring_lock, flags);
+		return -EAGAIN;
+	}
+
+	/* Write to the ring buffer */
+	next_write_location = hv_get_next_write_location(outring_info);
+
+	old_write = next_write_location;
+
+	for (i = 0; i < kv_count; i++) {
+		next_write_location = hv_copyto_ringbuffer(outring_info,
+						     next_write_location,
+						     kv_list[i].iov_base,
+						     kv_list[i].iov_len);
+	}
+
+	/* Set previous packet start */
+	prev_indices = hv_get_ring_bufferindices(outring_info);
+
+	next_write_location = hv_copyto_ringbuffer(outring_info,
+					     next_write_location,
+					     &prev_indices,
+					     sizeof(u64));
+
+	/* Issue a full memory barrier before updating the write index */
+	mb();
+
+	/* Now, update the write location */
+	hv_set_next_write_location(outring_info, next_write_location);
+
+
+	spin_unlock_irqrestore(&outring_info->ring_lock, flags);
+
+	*signal = hv_need_to_signal(old_write, outring_info);
+	return 0;
+}
+
+
+/*
+ *
+ * hv_ringbuffer_peek()
+ *
+ * Read without advancing the read index
+ *
+ */
+int hv_ringbuffer_peek(struct hv_ring_buffer_info *Inring_info,
+		   void *Buffer, u32 buflen)
+{
+	u32 bytes_avail_towrite;
+	u32 bytes_avail_toread;
+	u32 next_read_location = 0;
+	unsigned long flags;
+
+	spin_lock_irqsave(&Inring_info->ring_lock, flags);
+
+	hv_get_ringbuffer_availbytes(Inring_info,
+				&bytes_avail_toread,
+				&bytes_avail_towrite);
+
+	/* Make sure there is something to read */
+	if (bytes_avail_toread < buflen) {
+
+		spin_unlock_irqrestore(&Inring_info->ring_lock, flags);
+
+		return -EAGAIN;
+	}
+
+	/* Convert to byte offset */
+	next_read_location = hv_get_next_read_location(Inring_info);
+
+	next_read_location = hv_copyfrom_ringbuffer(Inring_info,
+						Buffer,
+						buflen,
+						next_read_location);
+
+	spin_unlock_irqrestore(&Inring_info->ring_lock, flags);
+
+	return 0;
+}
+
+
+/*
+ *
+ * hv_ringbuffer_read()
+ *
+ * Read and advance the read index
+ *
+ */
+int hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info, void *buffer,
+		   u32 buflen, u32 offset, bool *signal)
+{
+	u32 bytes_avail_towrite;
+	u32 bytes_avail_toread;
+	u32 next_read_location = 0;
+	u64 prev_indices = 0;
+	unsigned long flags;
+	u32 old_read;
+
+	if (buflen <= 0)
+		return -EINVAL;
+
+	spin_lock_irqsave(&inring_info->ring_lock, flags);
+
+	hv_get_ringbuffer_availbytes(inring_info,
+				&bytes_avail_toread,
+				&bytes_avail_towrite);
+
+	old_read = bytes_avail_toread;
+
+	/* Make sure there is something to read */
+	if (bytes_avail_toread < buflen) {
+		spin_unlock_irqrestore(&inring_info->ring_lock, flags);
+
+		return -EAGAIN;
+	}
+
+	next_read_location =
+		hv_get_next_readlocation_withoffset(inring_info, offset);
+
+	next_read_location = hv_copyfrom_ringbuffer(inring_info,
+						buffer,
+						buflen,
+						next_read_location);
+
+	next_read_location = hv_copyfrom_ringbuffer(inring_info,
+						&prev_indices,
+						sizeof(u64),
+						next_read_location);
+
+	/* Make sure all reads are done before we update the read index since */
+	/* the writer may start writing to the read area once the read index */
+	/*is updated */
+	mb();
+
+	/* Update the read index */
+	hv_set_next_read_location(inring_info, next_read_location);
+
+	spin_unlock_irqrestore(&inring_info->ring_lock, flags);
+
+	*signal = hv_need_to_signal_on_read(old_read, inring_info);
+
+	return 0;
+}
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
new file mode 100644
index 000000000..c85235e9f
--- /dev/null
+++ b/drivers/hv/vmbus_drv.c
@@ -0,0 +1,1114 @@
+/*
+ * Copyright (c) 2009, Microsoft Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
+ * Place - Suite 330, Boston, MA 02111-1307 USA.
+ *
+ * Authors:
+ *   Haiyang Zhang <haiyangz@microsoft.com>
+ *   Hank Janssen  <hjanssen@microsoft.com>
+ *   K. Y. Srinivasan <kys@microsoft.com>
+ *
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/interrupt.h>
+#include <linux/sysctl.h>
+#include <linux/slab.h>
+#include <linux/acpi.h>
+#include <linux/completion.h>
+#include <linux/hyperv.h>
+#include <linux/kernel_stat.h>
+#include <linux/clockchips.h>
+#include <linux/cpu.h>
+#include <asm/hyperv.h>
+#include <asm/hypervisor.h>
+#include <asm/mshyperv.h>
+#include <linux/notifier.h>
+#include <linux/ptrace.h>
+#include "hyperv_vmbus.h"
+
+static struct acpi_device  *hv_acpi_dev;
+
+static struct tasklet_struct msg_dpc;
+static struct completion probe_event;
+static int irq;
+
+
+static int hyperv_panic_event(struct notifier_block *nb,
+			unsigned long event, void *ptr)
+{
+	struct pt_regs *regs;
+
+	regs = current_pt_regs();
+
+	wrmsrl(HV_X64_MSR_CRASH_P0, regs->ip);
+	wrmsrl(HV_X64_MSR_CRASH_P1, regs->ax);
+	wrmsrl(HV_X64_MSR_CRASH_P2, regs->bx);
+	wrmsrl(HV_X64_MSR_CRASH_P3, regs->cx);
+	wrmsrl(HV_X64_MSR_CRASH_P4, regs->dx);
+
+	/*
+	 * Let Hyper-V know there is crash data available
+	 */
+	wrmsrl(HV_X64_MSR_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY);
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block hyperv_panic_block = {
+	.notifier_call = hyperv_panic_event,
+};
+
+struct resource hyperv_mmio = {
+	.name  = "hyperv mmio",
+	.flags = IORESOURCE_MEM,
+};
+EXPORT_SYMBOL_GPL(hyperv_mmio);
+
+static int vmbus_exists(void)
+{
+	if (hv_acpi_dev == NULL)
+		return -ENODEV;
+
+	return 0;
+}
+
+#define VMBUS_ALIAS_LEN ((sizeof((struct hv_vmbus_device_id *)0)->guid) * 2)
+static void print_alias_name(struct hv_device *hv_dev, char *alias_name)
+{
+	int i;
+	for (i = 0; i < VMBUS_ALIAS_LEN; i += 2)
+		sprintf(&alias_name[i], "%02x", hv_dev->dev_type.b[i/2]);
+}
+
+static u8 channel_monitor_group(struct vmbus_channel *channel)
+{
+	return (u8)channel->offermsg.monitorid / 32;
+}
+
+static u8 channel_monitor_offset(struct vmbus_channel *channel)
+{
+	return (u8)channel->offermsg.monitorid % 32;
+}
+
+static u32 channel_pending(struct vmbus_channel *channel,
+			   struct hv_monitor_page *monitor_page)
+{
+	u8 monitor_group = channel_monitor_group(channel);
+	return monitor_page->trigger_group[monitor_group].pending;
+}
+
+static u32 channel_latency(struct vmbus_channel *channel,
+			   struct hv_monitor_page *monitor_page)
+{
+	u8 monitor_group = channel_monitor_group(channel);
+	u8 monitor_offset = channel_monitor_offset(channel);
+	return monitor_page->latency[monitor_group][monitor_offset];
+}
+
+static u32 channel_conn_id(struct vmbus_channel *channel,
+			   struct hv_monitor_page *monitor_page)
+{
+	u8 monitor_group = channel_monitor_group(channel);
+	u8 monitor_offset = channel_monitor_offset(channel);
+	return monitor_page->parameter[monitor_group][monitor_offset].connectionid.u.id;
+}
+
+static ssize_t id_show(struct device *dev, struct device_attribute *dev_attr,
+		       char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+	return sprintf(buf, "%d\n", hv_dev->channel->offermsg.child_relid);
+}
+static DEVICE_ATTR_RO(id);
+
+static ssize_t state_show(struct device *dev, struct device_attribute *dev_attr,
+			  char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+	return sprintf(buf, "%d\n", hv_dev->channel->state);
+}
+static DEVICE_ATTR_RO(state);
+
+static ssize_t monitor_id_show(struct device *dev,
+			       struct device_attribute *dev_attr, char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+	return sprintf(buf, "%d\n", hv_dev->channel->offermsg.monitorid);
+}
+static DEVICE_ATTR_RO(monitor_id);
+
+static ssize_t class_id_show(struct device *dev,
+			       struct device_attribute *dev_attr, char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+	return sprintf(buf, "{%pUl}\n",
+		       hv_dev->channel->offermsg.offer.if_type.b);
+}
+static DEVICE_ATTR_RO(class_id);
+
+static ssize_t device_id_show(struct device *dev,
+			      struct device_attribute *dev_attr, char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+	return sprintf(buf, "{%pUl}\n",
+		       hv_dev->channel->offermsg.offer.if_instance.b);
+}
+static DEVICE_ATTR_RO(device_id);
+
+static ssize_t modalias_show(struct device *dev,
+			     struct device_attribute *dev_attr, char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+	char alias_name[VMBUS_ALIAS_LEN + 1];
+
+	print_alias_name(hv_dev, alias_name);
+	return sprintf(buf, "vmbus:%s\n", alias_name);
+}
+static DEVICE_ATTR_RO(modalias);
+
+static ssize_t server_monitor_pending_show(struct device *dev,
+					   struct device_attribute *dev_attr,
+					   char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+	return sprintf(buf, "%d\n",
+		       channel_pending(hv_dev->channel,
+				       vmbus_connection.monitor_pages[1]));
+}
+static DEVICE_ATTR_RO(server_monitor_pending);
+
+static ssize_t client_monitor_pending_show(struct device *dev,
+					   struct device_attribute *dev_attr,
+					   char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+	return sprintf(buf, "%d\n",
+		       channel_pending(hv_dev->channel,
+				       vmbus_connection.monitor_pages[1]));
+}
+static DEVICE_ATTR_RO(client_monitor_pending);
+
+static ssize_t server_monitor_latency_show(struct device *dev,
+					   struct device_attribute *dev_attr,
+					   char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+	return sprintf(buf, "%d\n",
+		       channel_latency(hv_dev->channel,
+				       vmbus_connection.monitor_pages[0]));
+}
+static DEVICE_ATTR_RO(server_monitor_latency);
+
+static ssize_t client_monitor_latency_show(struct device *dev,
+					   struct device_attribute *dev_attr,
+					   char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+	return sprintf(buf, "%d\n",
+		       channel_latency(hv_dev->channel,
+				       vmbus_connection.monitor_pages[1]));
+}
+static DEVICE_ATTR_RO(client_monitor_latency);
+
+static ssize_t server_monitor_conn_id_show(struct device *dev,
+					   struct device_attribute *dev_attr,
+					   char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+	return sprintf(buf, "%d\n",
+		       channel_conn_id(hv_dev->channel,
+				       vmbus_connection.monitor_pages[0]));
+}
+static DEVICE_ATTR_RO(server_monitor_conn_id);
+
+static ssize_t client_monitor_conn_id_show(struct device *dev,
+					   struct device_attribute *dev_attr,
+					   char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+	return sprintf(buf, "%d\n",
+		       channel_conn_id(hv_dev->channel,
+				       vmbus_connection.monitor_pages[1]));
+}
+static DEVICE_ATTR_RO(client_monitor_conn_id);
+
+static ssize_t out_intr_mask_show(struct device *dev,
+				  struct device_attribute *dev_attr, char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+	struct hv_ring_buffer_debug_info outbound;
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+	hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound, &outbound);
+	return sprintf(buf, "%d\n", outbound.current_interrupt_mask);
+}
+static DEVICE_ATTR_RO(out_intr_mask);
+
+static ssize_t out_read_index_show(struct device *dev,
+				   struct device_attribute *dev_attr, char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+	struct hv_ring_buffer_debug_info outbound;
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+	hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound, &outbound);
+	return sprintf(buf, "%d\n", outbound.current_read_index);
+}
+static DEVICE_ATTR_RO(out_read_index);
+
+static ssize_t out_write_index_show(struct device *dev,
+				    struct device_attribute *dev_attr,
+				    char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+	struct hv_ring_buffer_debug_info outbound;
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+	hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound, &outbound);
+	return sprintf(buf, "%d\n", outbound.current_write_index);
+}
+static DEVICE_ATTR_RO(out_write_index);
+
+static ssize_t out_read_bytes_avail_show(struct device *dev,
+					 struct device_attribute *dev_attr,
+					 char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+	struct hv_ring_buffer_debug_info outbound;
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+	hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound, &outbound);
+	return sprintf(buf, "%d\n", outbound.bytes_avail_toread);
+}
+static DEVICE_ATTR_RO(out_read_bytes_avail);
+
+static ssize_t out_write_bytes_avail_show(struct device *dev,
+					  struct device_attribute *dev_attr,
+					  char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+	struct hv_ring_buffer_debug_info outbound;
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+	hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound, &outbound);
+	return sprintf(buf, "%d\n", outbound.bytes_avail_towrite);
+}
+static DEVICE_ATTR_RO(out_write_bytes_avail);
+
+static ssize_t in_intr_mask_show(struct device *dev,
+				 struct device_attribute *dev_attr, char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+	struct hv_ring_buffer_debug_info inbound;
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+	hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
+	return sprintf(buf, "%d\n", inbound.current_interrupt_mask);
+}
+static DEVICE_ATTR_RO(in_intr_mask);
+
+static ssize_t in_read_index_show(struct device *dev,
+				  struct device_attribute *dev_attr, char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+	struct hv_ring_buffer_debug_info inbound;
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+	hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
+	return sprintf(buf, "%d\n", inbound.current_read_index);
+}
+static DEVICE_ATTR_RO(in_read_index);
+
+static ssize_t in_write_index_show(struct device *dev,
+				   struct device_attribute *dev_attr, char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+	struct hv_ring_buffer_debug_info inbound;
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+	hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
+	return sprintf(buf, "%d\n", inbound.current_write_index);
+}
+static DEVICE_ATTR_RO(in_write_index);
+
+static ssize_t in_read_bytes_avail_show(struct device *dev,
+					struct device_attribute *dev_attr,
+					char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+	struct hv_ring_buffer_debug_info inbound;
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+	hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
+	return sprintf(buf, "%d\n", inbound.bytes_avail_toread);
+}
+static DEVICE_ATTR_RO(in_read_bytes_avail);
+
+static ssize_t in_write_bytes_avail_show(struct device *dev,
+					 struct device_attribute *dev_attr,
+					 char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+	struct hv_ring_buffer_debug_info inbound;
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+	hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
+	return sprintf(buf, "%d\n", inbound.bytes_avail_towrite);
+}
+static DEVICE_ATTR_RO(in_write_bytes_avail);
+
+/* Set up per device attributes in /sys/bus/vmbus/devices/<bus device> */
+static struct attribute *vmbus_attrs[] = {
+	&dev_attr_id.attr,
+	&dev_attr_state.attr,
+	&dev_attr_monitor_id.attr,
+	&dev_attr_class_id.attr,
+	&dev_attr_device_id.attr,
+	&dev_attr_modalias.attr,
+	&dev_attr_server_monitor_pending.attr,
+	&dev_attr_client_monitor_pending.attr,
+	&dev_attr_server_monitor_latency.attr,
+	&dev_attr_client_monitor_latency.attr,
+	&dev_attr_server_monitor_conn_id.attr,
+	&dev_attr_client_monitor_conn_id.attr,
+	&dev_attr_out_intr_mask.attr,
+	&dev_attr_out_read_index.attr,
+	&dev_attr_out_write_index.attr,
+	&dev_attr_out_read_bytes_avail.attr,
+	&dev_attr_out_write_bytes_avail.attr,
+	&dev_attr_in_intr_mask.attr,
+	&dev_attr_in_read_index.attr,
+	&dev_attr_in_write_index.attr,
+	&dev_attr_in_read_bytes_avail.attr,
+	&dev_attr_in_write_bytes_avail.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(vmbus);
+
+/*
+ * vmbus_uevent - add uevent for our device
+ *
+ * This routine is invoked when a device is added or removed on the vmbus to
+ * generate a uevent to udev in the userspace. The udev will then look at its
+ * rule and the uevent generated here to load the appropriate driver
+ *
+ * The alias string will be of the form vmbus:guid where guid is the string
+ * representation of the device guid (each byte of the guid will be
+ * represented with two hex characters.
+ */
+static int vmbus_uevent(struct device *device, struct kobj_uevent_env *env)
+{
+	struct hv_device *dev = device_to_hv_device(device);
+	int ret;
+	char alias_name[VMBUS_ALIAS_LEN + 1];
+
+	print_alias_name(dev, alias_name);
+	ret = add_uevent_var(env, "MODALIAS=vmbus:%s", alias_name);
+	return ret;
+}
+
+static const uuid_le null_guid;
+
+static inline bool is_null_guid(const __u8 *guid)
+{
+	if (memcmp(guid, &null_guid, sizeof(uuid_le)))
+		return false;
+	return true;
+}
+
+/*
+ * Return a matching hv_vmbus_device_id pointer.
+ * If there is no match, return NULL.
+ */
+static const struct hv_vmbus_device_id *hv_vmbus_get_id(
+					const struct hv_vmbus_device_id *id,
+					const __u8 *guid)
+{
+	for (; !is_null_guid(id->guid); id++)
+		if (!memcmp(&id->guid, guid, sizeof(uuid_le)))
+			return id;
+
+	return NULL;
+}
+
+
+
+/*
+ * vmbus_match - Attempt to match the specified device to the specified driver
+ */
+static int vmbus_match(struct device *device, struct device_driver *driver)
+{
+	struct hv_driver *drv = drv_to_hv_drv(driver);
+	struct hv_device *hv_dev = device_to_hv_device(device);
+
+	if (hv_vmbus_get_id(drv->id_table, hv_dev->dev_type.b))
+		return 1;
+
+	return 0;
+}
+
+/*
+ * vmbus_probe - Add the new vmbus's child device
+ */
+static int vmbus_probe(struct device *child_device)
+{
+	int ret = 0;
+	struct hv_driver *drv =
+			drv_to_hv_drv(child_device->driver);
+	struct hv_device *dev = device_to_hv_device(child_device);
+	const struct hv_vmbus_device_id *dev_id;
+
+	dev_id = hv_vmbus_get_id(drv->id_table, dev->dev_type.b);
+	if (drv->probe) {
+		ret = drv->probe(dev, dev_id);
+		if (ret != 0)
+			pr_err("probe failed for device %s (%d)\n",
+			       dev_name(child_device), ret);
+
+	} else {
+		pr_err("probe not set for driver %s\n",
+		       dev_name(child_device));
+		ret = -ENODEV;
+	}
+	return ret;
+}
+
+/*
+ * vmbus_remove - Remove a vmbus device
+ */
+static int vmbus_remove(struct device *child_device)
+{
+	struct hv_driver *drv;
+	struct hv_device *dev = device_to_hv_device(child_device);
+	u32 relid = dev->channel->offermsg.child_relid;
+
+	if (child_device->driver) {
+		drv = drv_to_hv_drv(child_device->driver);
+		if (drv->remove)
+			drv->remove(dev);
+		else {
+			hv_process_channel_removal(dev->channel, relid);
+			pr_err("remove not set for driver %s\n",
+				dev_name(child_device));
+		}
+	} else {
+		/*
+		 * We don't have a driver for this device; deal with the
+		 * rescind message by removing the channel.
+		 */
+		hv_process_channel_removal(dev->channel, relid);
+	}
+
+	return 0;
+}
+
+
+/*
+ * vmbus_shutdown - Shutdown a vmbus device
+ */
+static void vmbus_shutdown(struct device *child_device)
+{
+	struct hv_driver *drv;
+	struct hv_device *dev = device_to_hv_device(child_device);
+
+
+	/* The device may not be attached yet */
+	if (!child_device->driver)
+		return;
+
+	drv = drv_to_hv_drv(child_device->driver);
+
+	if (drv->shutdown)
+		drv->shutdown(dev);
+
+	return;
+}
+
+
+/*
+ * vmbus_device_release - Final callback release of the vmbus child device
+ */
+static void vmbus_device_release(struct device *device)
+{
+	struct hv_device *hv_dev = device_to_hv_device(device);
+
+	kfree(hv_dev);
+
+}
+
+/* The one and only one */
+static struct bus_type  hv_bus = {
+	.name =		"vmbus",
+	.match =		vmbus_match,
+	.shutdown =		vmbus_shutdown,
+	.remove =		vmbus_remove,
+	.probe =		vmbus_probe,
+	.uevent =		vmbus_uevent,
+	.dev_groups =		vmbus_groups,
+};
+
+struct onmessage_work_context {
+	struct work_struct work;
+	struct hv_message msg;
+};
+
+static void vmbus_onmessage_work(struct work_struct *work)
+{
+	struct onmessage_work_context *ctx;
+
+	/* Do not process messages if we're in DISCONNECTED state */
+	if (vmbus_connection.conn_state == DISCONNECTED)
+		return;
+
+	ctx = container_of(work, struct onmessage_work_context,
+			   work);
+	vmbus_onmessage(&ctx->msg);
+	kfree(ctx);
+}
+
+static void hv_process_timer_expiration(struct hv_message *msg, int cpu)
+{
+	struct clock_event_device *dev = hv_context.clk_evt[cpu];
+
+	if (dev->event_handler)
+		dev->event_handler(dev);
+
+	msg->header.message_type = HVMSG_NONE;
+
+	/*
+	 * Make sure the write to MessageType (ie set to
+	 * HVMSG_NONE) happens before we read the
+	 * MessagePending and EOMing. Otherwise, the EOMing
+	 * will not deliver any more messages since there is
+	 * no empty slot
+	 */
+	mb();
+
+	if (msg->header.message_flags.msg_pending) {
+		/*
+		 * This will cause message queue rescan to
+		 * possibly deliver another msg from the
+		 * hypervisor
+		 */
+		wrmsrl(HV_X64_MSR_EOM, 0);
+	}
+}
+
+static void vmbus_on_msg_dpc(unsigned long data)
+{
+	int cpu = smp_processor_id();
+	void *page_addr = hv_context.synic_message_page[cpu];
+	struct hv_message *msg = (struct hv_message *)page_addr +
+				  VMBUS_MESSAGE_SINT;
+	struct vmbus_channel_message_header *hdr;
+	struct vmbus_channel_message_table_entry *entry;
+	struct onmessage_work_context *ctx;
+
+	while (1) {
+		if (msg->header.message_type == HVMSG_NONE)
+			/* no msg */
+			break;
+
+		hdr = (struct vmbus_channel_message_header *)msg->u.payload;
+
+		if (hdr->msgtype >= CHANNELMSG_COUNT) {
+			WARN_ONCE(1, "unknown msgtype=%d\n", hdr->msgtype);
+			goto msg_handled;
+		}
+
+		entry = &channel_message_table[hdr->msgtype];
+		if (entry->handler_type	== VMHT_BLOCKING) {
+			ctx = kmalloc(sizeof(*ctx), GFP_ATOMIC);
+			if (ctx == NULL)
+				continue;
+
+			INIT_WORK(&ctx->work, vmbus_onmessage_work);
+			memcpy(&ctx->msg, msg, sizeof(*msg));
+
+			queue_work(vmbus_connection.work_queue, &ctx->work);
+		} else
+			entry->message_handler(hdr);
+
+msg_handled:
+		msg->header.message_type = HVMSG_NONE;
+
+		/*
+		 * Make sure the write to MessageType (ie set to
+		 * HVMSG_NONE) happens before we read the
+		 * MessagePending and EOMing. Otherwise, the EOMing
+		 * will not deliver any more messages since there is
+		 * no empty slot
+		 */
+		mb();
+
+		if (msg->header.message_flags.msg_pending) {
+			/*
+			 * This will cause message queue rescan to
+			 * possibly deliver another msg from the
+			 * hypervisor
+			 */
+			wrmsrl(HV_X64_MSR_EOM, 0);
+		}
+	}
+}
+
+static void vmbus_isr(void)
+{
+	int cpu = smp_processor_id();
+	void *page_addr;
+	struct hv_message *msg;
+	union hv_synic_event_flags *event;
+	bool handled = false;
+
+	page_addr = hv_context.synic_event_page[cpu];
+	if (page_addr == NULL)
+		return;
+
+	event = (union hv_synic_event_flags *)page_addr +
+					 VMBUS_MESSAGE_SINT;
+	/*
+	 * Check for events before checking for messages. This is the order
+	 * in which events and messages are checked in Windows guests on
+	 * Hyper-V, and the Windows team suggested we do the same.
+	 */
+
+	if ((vmbus_proto_version == VERSION_WS2008) ||
+		(vmbus_proto_version == VERSION_WIN7)) {
+
+		/* Since we are a child, we only need to check bit 0 */
+		if (sync_test_and_clear_bit(0,
+			(unsigned long *) &event->flags32[0])) {
+			handled = true;
+		}
+	} else {
+		/*
+		 * Our host is win8 or above. The signaling mechanism
+		 * has changed and we can directly look at the event page.
+		 * If bit n is set then we have an interrup on the channel
+		 * whose id is n.
+		 */
+		handled = true;
+	}
+
+	if (handled)
+		tasklet_schedule(hv_context.event_dpc[cpu]);
+
+
+	page_addr = hv_context.synic_message_page[cpu];
+	msg = (struct hv_message *)page_addr + VMBUS_MESSAGE_SINT;
+
+	/* Check if there are actual msgs to be processed */
+	if (msg->header.message_type != HVMSG_NONE) {
+		if (msg->header.message_type == HVMSG_TIMER_EXPIRED)
+			hv_process_timer_expiration(msg, cpu);
+		else
+			tasklet_schedule(&msg_dpc);
+	}
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+static int hyperv_cpu_disable(void)
+{
+	return -ENOSYS;
+}
+
+static void hv_cpu_hotplug_quirk(bool vmbus_loaded)
+{
+	static void *previous_cpu_disable;
+
+	/*
+	 * Offlining a CPU when running on newer hypervisors (WS2012R2, Win8,
+	 * ...) is not supported at this moment as channel interrupts are
+	 * distributed across all of them.
+	 */
+
+	if ((vmbus_proto_version == VERSION_WS2008) ||
+	    (vmbus_proto_version == VERSION_WIN7))
+		return;
+
+	if (vmbus_loaded) {
+		previous_cpu_disable = smp_ops.cpu_disable;
+		smp_ops.cpu_disable = hyperv_cpu_disable;
+		pr_notice("CPU offlining is not supported by hypervisor\n");
+	} else if (previous_cpu_disable)
+		smp_ops.cpu_disable = previous_cpu_disable;
+}
+#else
+static void hv_cpu_hotplug_quirk(bool vmbus_loaded)
+{
+}
+#endif
+
+/*
+ * vmbus_bus_init -Main vmbus driver initialization routine.
+ *
+ * Here, we
+ *	- initialize the vmbus driver context
+ *	- invoke the vmbus hv main init routine
+ *	- get the irq resource
+ *	- retrieve the channel offers
+ */
+static int vmbus_bus_init(int irq)
+{
+	int ret;
+
+	/* Hypervisor initialization...setup hypercall page..etc */
+	ret = hv_init();
+	if (ret != 0) {
+		pr_err("Unable to initialize the hypervisor - 0x%x\n", ret);
+		return ret;
+	}
+
+	tasklet_init(&msg_dpc, vmbus_on_msg_dpc, 0);
+
+	ret = bus_register(&hv_bus);
+	if (ret)
+		goto err_cleanup;
+
+	hv_setup_vmbus_irq(vmbus_isr);
+
+	ret = hv_synic_alloc();
+	if (ret)
+		goto err_alloc;
+	/*
+	 * Initialize the per-cpu interrupt state and
+	 * connect to the host.
+	 */
+	on_each_cpu(hv_synic_init, NULL, 1);
+	ret = vmbus_connect();
+	if (ret)
+		goto err_alloc;
+
+	hv_cpu_hotplug_quirk(true);
+
+	/*
+	 * Only register if the crash MSRs are available
+	 */
+	if (ms_hyperv.features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE) {
+		atomic_notifier_chain_register(&panic_notifier_list,
+					       &hyperv_panic_block);
+	}
+
+	vmbus_request_offers();
+
+	return 0;
+
+err_alloc:
+	hv_synic_free();
+	hv_remove_vmbus_irq();
+
+	bus_unregister(&hv_bus);
+
+err_cleanup:
+	hv_cleanup();
+
+	return ret;
+}
+
+/**
+ * __vmbus_child_driver_register - Register a vmbus's driver
+ * @drv: Pointer to driver structure you want to register
+ * @owner: owner module of the drv
+ * @mod_name: module name string
+ *
+ * Registers the given driver with Linux through the 'driver_register()' call
+ * and sets up the hyper-v vmbus handling for this driver.
+ * It will return the state of the 'driver_register()' call.
+ *
+ */
+int __vmbus_driver_register(struct hv_driver *hv_driver, struct module *owner, const char *mod_name)
+{
+	int ret;
+
+	pr_info("registering driver %s\n", hv_driver->name);
+
+	ret = vmbus_exists();
+	if (ret < 0)
+		return ret;
+
+	hv_driver->driver.name = hv_driver->name;
+	hv_driver->driver.owner = owner;
+	hv_driver->driver.mod_name = mod_name;
+	hv_driver->driver.bus = &hv_bus;
+
+	ret = driver_register(&hv_driver->driver);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(__vmbus_driver_register);
+
+/**
+ * vmbus_driver_unregister() - Unregister a vmbus's driver
+ * @drv: Pointer to driver structure you want to un-register
+ *
+ * Un-register the given driver that was previous registered with a call to
+ * vmbus_driver_register()
+ */
+void vmbus_driver_unregister(struct hv_driver *hv_driver)
+{
+	pr_info("unregistering driver %s\n", hv_driver->name);
+
+	if (!vmbus_exists())
+		driver_unregister(&hv_driver->driver);
+}
+EXPORT_SYMBOL_GPL(vmbus_driver_unregister);
+
+/*
+ * vmbus_device_create - Creates and registers a new child device
+ * on the vmbus.
+ */
+struct hv_device *vmbus_device_create(const uuid_le *type,
+				      const uuid_le *instance,
+				      struct vmbus_channel *channel)
+{
+	struct hv_device *child_device_obj;
+
+	child_device_obj = kzalloc(sizeof(struct hv_device), GFP_KERNEL);
+	if (!child_device_obj) {
+		pr_err("Unable to allocate device object for child device\n");
+		return NULL;
+	}
+
+	child_device_obj->channel = channel;
+	memcpy(&child_device_obj->dev_type, type, sizeof(uuid_le));
+	memcpy(&child_device_obj->dev_instance, instance,
+	       sizeof(uuid_le));
+
+
+	return child_device_obj;
+}
+
+/*
+ * vmbus_device_register - Register the child device
+ */
+int vmbus_device_register(struct hv_device *child_device_obj)
+{
+	int ret = 0;
+
+	dev_set_name(&child_device_obj->device, "vmbus_%d",
+		     child_device_obj->channel->id);
+
+	child_device_obj->device.bus = &hv_bus;
+	child_device_obj->device.parent = &hv_acpi_dev->dev;
+	child_device_obj->device.release = vmbus_device_release;
+
+	/*
+	 * Register with the LDM. This will kick off the driver/device
+	 * binding...which will eventually call vmbus_match() and vmbus_probe()
+	 */
+	ret = device_register(&child_device_obj->device);
+
+	if (ret)
+		pr_err("Unable to register child device\n");
+	else
+		pr_debug("child device %s registered\n",
+			dev_name(&child_device_obj->device));
+
+	return ret;
+}
+
+/*
+ * vmbus_device_unregister - Remove the specified child device
+ * from the vmbus.
+ */
+void vmbus_device_unregister(struct hv_device *device_obj)
+{
+	pr_debug("child device %s unregistered\n",
+		dev_name(&device_obj->device));
+
+	/*
+	 * Kick off the process of unregistering the device.
+	 * This will call vmbus_remove() and eventually vmbus_device_release()
+	 */
+	device_unregister(&device_obj->device);
+}
+
+
+/*
+ * VMBUS is an acpi enumerated device. Get the the information we
+ * need from DSDT.
+ */
+
+static acpi_status vmbus_walk_resources(struct acpi_resource *res, void *ctx)
+{
+	switch (res->type) {
+	case ACPI_RESOURCE_TYPE_IRQ:
+		irq = res->data.irq.interrupts[0];
+		break;
+
+	case ACPI_RESOURCE_TYPE_ADDRESS64:
+		hyperv_mmio.start = res->data.address64.address.minimum;
+		hyperv_mmio.end = res->data.address64.address.maximum;
+		break;
+	}
+
+	return AE_OK;
+}
+
+static int vmbus_acpi_add(struct acpi_device *device)
+{
+	acpi_status result;
+	int ret_val = -ENODEV;
+
+	hv_acpi_dev = device;
+
+	result = acpi_walk_resources(device->handle, METHOD_NAME__CRS,
+					vmbus_walk_resources, NULL);
+
+	if (ACPI_FAILURE(result))
+		goto acpi_walk_err;
+	/*
+	 * The parent of the vmbus acpi device (Gen2 firmware) is the VMOD that
+	 * has the mmio ranges. Get that.
+	 */
+	if (device->parent) {
+		result = acpi_walk_resources(device->parent->handle,
+					METHOD_NAME__CRS,
+					vmbus_walk_resources, NULL);
+
+		if (ACPI_FAILURE(result))
+			goto acpi_walk_err;
+		if (hyperv_mmio.start && hyperv_mmio.end)
+			request_resource(&iomem_resource, &hyperv_mmio);
+	}
+	ret_val = 0;
+
+acpi_walk_err:
+	complete(&probe_event);
+	return ret_val;
+}
+
+static const struct acpi_device_id vmbus_acpi_device_ids[] = {
+	{"VMBUS", 0},
+	{"VMBus", 0},
+	{"", 0},
+};
+MODULE_DEVICE_TABLE(acpi, vmbus_acpi_device_ids);
+
+static struct acpi_driver vmbus_acpi_driver = {
+	.name = "vmbus",
+	.ids = vmbus_acpi_device_ids,
+	.ops = {
+		.add = vmbus_acpi_add,
+	},
+};
+
+static int __init hv_acpi_init(void)
+{
+	int ret, t;
+
+	if (x86_hyper != &x86_hyper_ms_hyperv)
+		return -ENODEV;
+
+	init_completion(&probe_event);
+
+	/*
+	 * Get irq resources first.
+	 */
+	ret = acpi_bus_register_driver(&vmbus_acpi_driver);
+
+	if (ret)
+		return ret;
+
+	t = wait_for_completion_timeout(&probe_event, 5*HZ);
+	if (t == 0) {
+		ret = -ETIMEDOUT;
+		goto cleanup;
+	}
+
+	if (irq <= 0) {
+		ret = -ENODEV;
+		goto cleanup;
+	}
+
+	ret = vmbus_bus_init(irq);
+	if (ret)
+		goto cleanup;
+
+	return 0;
+
+cleanup:
+	acpi_bus_unregister_driver(&vmbus_acpi_driver);
+	hv_acpi_dev = NULL;
+	return ret;
+}
+
+static void __exit vmbus_exit(void)
+{
+	int cpu;
+
+	vmbus_connection.conn_state = DISCONNECTED;
+	hv_synic_clockevents_cleanup();
+	hv_remove_vmbus_irq();
+	vmbus_free_channels();
+	bus_unregister(&hv_bus);
+	hv_cleanup();
+	for_each_online_cpu(cpu)
+		smp_call_function_single(cpu, hv_synic_cleanup, NULL, 1);
+	acpi_bus_unregister_driver(&vmbus_acpi_driver);
+	hv_cpu_hotplug_quirk(false);
+	vmbus_disconnect();
+}
+
+
+MODULE_LICENSE("GPL");
+
+subsys_initcall(hv_acpi_init);
+module_exit(vmbus_exit);