Initial import

1 files changed, 1138 insertions, 0 deletions

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
new file mode 100644
index 000000000..7d137a43c
--- /dev/null
+++ b/drivers/vhost/net.c
@@ -0,0 +1,1138 @@
+/* Copyright (C) 2009 Red Hat, Inc.
+ * Author: Michael S. Tsirkin <mst@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.
+ *
+ * virtio-net server in host kernel.
+ */
+
+#include <linux/compat.h>
+#include <linux/eventfd.h>
+#include <linux/vhost.h>
+#include <linux/virtio_net.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/mutex.h>
+#include <linux/workqueue.h>
+#include <linux/file.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+
+#include <linux/net.h>
+#include <linux/if_packet.h>
+#include <linux/if_arp.h>
+#include <linux/if_tun.h>
+#include <linux/if_macvlan.h>
+#include <linux/if_vlan.h>
+
+#include <net/sock.h>
+
+#include "vhost.h"
+
+static int experimental_zcopytx = 1;
+module_param(experimental_zcopytx, int, 0444);
+MODULE_PARM_DESC(experimental_zcopytx, "Enable Zero Copy TX;"
+		                       " 1 -Enable; 0 - Disable");
+
+/* Max number of bytes transferred before requeueing the job.
+ * Using this limit prevents one virtqueue from starving others. */
+#define VHOST_NET_WEIGHT 0x80000
+
+/* MAX number of TX used buffers for outstanding zerocopy */
+#define VHOST_MAX_PEND 128
+#define VHOST_GOODCOPY_LEN 256
+
+/*
+ * For transmit, used buffer len is unused; we override it to track buffer
+ * status internally; used for zerocopy tx only.
+ */
+/* Lower device DMA failed */
+#define VHOST_DMA_FAILED_LEN	((__force __virtio32)3)
+/* Lower device DMA done */
+#define VHOST_DMA_DONE_LEN	((__force __virtio32)2)
+/* Lower device DMA in progress */
+#define VHOST_DMA_IN_PROGRESS	((__force __virtio32)1)
+/* Buffer unused */
+#define VHOST_DMA_CLEAR_LEN	((__force __virtio32)0)
+
+#define VHOST_DMA_IS_DONE(len) ((__force u32)(len) >= (__force u32)VHOST_DMA_DONE_LEN)
+
+enum {
+	VHOST_NET_FEATURES = VHOST_FEATURES |
+			 (1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
+			 (1ULL << VIRTIO_NET_F_MRG_RXBUF) |
+			 (1ULL << VIRTIO_F_VERSION_1),
+};
+
+enum {
+	VHOST_NET_VQ_RX = 0,
+	VHOST_NET_VQ_TX = 1,
+	VHOST_NET_VQ_MAX = 2,
+};
+
+struct vhost_net_ubuf_ref {
+	/* refcount follows semantics similar to kref:
+	 *  0: object is released
+	 *  1: no outstanding ubufs
+	 * >1: outstanding ubufs
+	 */
+	atomic_t refcount;
+	wait_queue_head_t wait;
+	struct vhost_virtqueue *vq;
+};
+
+struct vhost_net_virtqueue {
+	struct vhost_virtqueue vq;
+	size_t vhost_hlen;
+	size_t sock_hlen;
+	/* vhost zerocopy support fields below: */
+	/* last used idx for outstanding DMA zerocopy buffers */
+	int upend_idx;
+	/* first used idx for DMA done zerocopy buffers */
+	int done_idx;
+	/* an array of userspace buffers info */
+	struct ubuf_info *ubuf_info;
+	/* Reference counting for outstanding ubufs.
+	 * Protected by vq mutex. Writers must also take device mutex. */
+	struct vhost_net_ubuf_ref *ubufs;
+};
+
+struct vhost_net {
+	struct vhost_dev dev;
+	struct vhost_net_virtqueue vqs[VHOST_NET_VQ_MAX];
+	struct vhost_poll poll[VHOST_NET_VQ_MAX];
+	/* Number of TX recently submitted.
+	 * Protected by tx vq lock. */
+	unsigned tx_packets;
+	/* Number of times zerocopy TX recently failed.
+	 * Protected by tx vq lock. */
+	unsigned tx_zcopy_err;
+	/* Flush in progress. Protected by tx vq lock. */
+	bool tx_flush;
+};
+
+static unsigned vhost_net_zcopy_mask __read_mostly;
+
+static void vhost_net_enable_zcopy(int vq)
+{
+	vhost_net_zcopy_mask |= 0x1 << vq;
+}
+
+static struct vhost_net_ubuf_ref *
+vhost_net_ubuf_alloc(struct vhost_virtqueue *vq, bool zcopy)
+{
+	struct vhost_net_ubuf_ref *ubufs;
+	/* No zero copy backend? Nothing to count. */
+	if (!zcopy)
+		return NULL;
+	ubufs = kmalloc(sizeof(*ubufs), GFP_KERNEL);
+	if (!ubufs)
+		return ERR_PTR(-ENOMEM);
+	atomic_set(&ubufs->refcount, 1);
+	init_waitqueue_head(&ubufs->wait);
+	ubufs->vq = vq;
+	return ubufs;
+}
+
+static int vhost_net_ubuf_put(struct vhost_net_ubuf_ref *ubufs)
+{
+	int r = atomic_sub_return(1, &ubufs->refcount);
+	if (unlikely(!r))
+		wake_up(&ubufs->wait);
+	return r;
+}
+
+static void vhost_net_ubuf_put_and_wait(struct vhost_net_ubuf_ref *ubufs)
+{
+	vhost_net_ubuf_put(ubufs);
+	wait_event(ubufs->wait, !atomic_read(&ubufs->refcount));
+}
+
+static void vhost_net_ubuf_put_wait_and_free(struct vhost_net_ubuf_ref *ubufs)
+{
+	vhost_net_ubuf_put_and_wait(ubufs);
+	kfree(ubufs);
+}
+
+static void vhost_net_clear_ubuf_info(struct vhost_net *n)
+{
+	int i;
+
+	for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
+		kfree(n->vqs[i].ubuf_info);
+		n->vqs[i].ubuf_info = NULL;
+	}
+}
+
+static int vhost_net_set_ubuf_info(struct vhost_net *n)
+{
+	bool zcopy;
+	int i;
+
+	for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
+		zcopy = vhost_net_zcopy_mask & (0x1 << i);
+		if (!zcopy)
+			continue;
+		n->vqs[i].ubuf_info = kmalloc(sizeof(*n->vqs[i].ubuf_info) *
+					      UIO_MAXIOV, GFP_KERNEL);
+		if  (!n->vqs[i].ubuf_info)
+			goto err;
+	}
+	return 0;
+
+err:
+	vhost_net_clear_ubuf_info(n);
+	return -ENOMEM;
+}
+
+static void vhost_net_vq_reset(struct vhost_net *n)
+{
+	int i;
+
+	vhost_net_clear_ubuf_info(n);
+
+	for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
+		n->vqs[i].done_idx = 0;
+		n->vqs[i].upend_idx = 0;
+		n->vqs[i].ubufs = NULL;
+		n->vqs[i].vhost_hlen = 0;
+		n->vqs[i].sock_hlen = 0;
+	}
+
+}
+
+static void vhost_net_tx_packet(struct vhost_net *net)
+{
+	++net->tx_packets;
+	if (net->tx_packets < 1024)
+		return;
+	net->tx_packets = 0;
+	net->tx_zcopy_err = 0;
+}
+
+static void vhost_net_tx_err(struct vhost_net *net)
+{
+	++net->tx_zcopy_err;
+}
+
+static bool vhost_net_tx_select_zcopy(struct vhost_net *net)
+{
+	/* TX flush waits for outstanding DMAs to be done.
+	 * Don't start new DMAs.
+	 */
+	return !net->tx_flush &&
+		net->tx_packets / 64 >= net->tx_zcopy_err;
+}
+
+static bool vhost_sock_zcopy(struct socket *sock)
+{
+	return unlikely(experimental_zcopytx) &&
+		sock_flag(sock->sk, SOCK_ZEROCOPY);
+}
+
+/* In case of DMA done not in order in lower device driver for some reason.
+ * upend_idx is used to track end of used idx, done_idx is used to track head
+ * of used idx. Once lower device DMA done contiguously, we will signal KVM
+ * guest used idx.
+ */
+static void vhost_zerocopy_signal_used(struct vhost_net *net,
+				       struct vhost_virtqueue *vq)
+{
+	struct vhost_net_virtqueue *nvq =
+		container_of(vq, struct vhost_net_virtqueue, vq);
+	int i, add;
+	int j = 0;
+
+	for (i = nvq->done_idx; i != nvq->upend_idx; i = (i + 1) % UIO_MAXIOV) {
+		if (vq->heads[i].len == VHOST_DMA_FAILED_LEN)
+			vhost_net_tx_err(net);
+		if (VHOST_DMA_IS_DONE(vq->heads[i].len)) {
+			vq->heads[i].len = VHOST_DMA_CLEAR_LEN;
+			++j;
+		} else
+			break;
+	}
+	while (j) {
+		add = min(UIO_MAXIOV - nvq->done_idx, j);
+		vhost_add_used_and_signal_n(vq->dev, vq,
+					    &vq->heads[nvq->done_idx], add);
+		nvq->done_idx = (nvq->done_idx + add) % UIO_MAXIOV;
+		j -= add;
+	}
+}
+
+static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success)
+{
+	struct vhost_net_ubuf_ref *ubufs = ubuf->ctx;
+	struct vhost_virtqueue *vq = ubufs->vq;
+	int cnt;
+
+	rcu_read_lock_bh();
+
+	/* set len to mark this desc buffers done DMA */
+	vq->heads[ubuf->desc].len = success ?
+		VHOST_DMA_DONE_LEN : VHOST_DMA_FAILED_LEN;
+	cnt = vhost_net_ubuf_put(ubufs);
+
+	/*
+	 * Trigger polling thread if guest stopped submitting new buffers:
+	 * in this case, the refcount after decrement will eventually reach 1.
+	 * We also trigger polling periodically after each 16 packets
+	 * (the value 16 here is more or less arbitrary, it's tuned to trigger
+	 * less than 10% of times).
+	 */
+	if (cnt <= 1 || !(cnt % 16))
+		vhost_poll_queue(&vq->poll);
+
+	rcu_read_unlock_bh();
+}
+
+/* Expects to be always run from workqueue - which acts as
+ * read-size critical section for our kind of RCU. */
+static void handle_tx(struct vhost_net *net)
+{
+	struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
+	struct vhost_virtqueue *vq = &nvq->vq;
+	unsigned out, in;
+	int head;
+	struct msghdr msg = {
+		.msg_name = NULL,
+		.msg_namelen = 0,
+		.msg_control = NULL,
+		.msg_controllen = 0,
+		.msg_flags = MSG_DONTWAIT,
+	};
+	size_t len, total_len = 0;
+	int err;
+	size_t hdr_size;
+	struct socket *sock;
+	struct vhost_net_ubuf_ref *uninitialized_var(ubufs);
+	bool zcopy, zcopy_used;
+
+	mutex_lock(&vq->mutex);
+	sock = vq->private_data;
+	if (!sock)
+		goto out;
+
+	vhost_disable_notify(&net->dev, vq);
+
+	hdr_size = nvq->vhost_hlen;
+	zcopy = nvq->ubufs;
+
+	for (;;) {
+		/* Release DMAs done buffers first */
+		if (zcopy)
+			vhost_zerocopy_signal_used(net, vq);
+
+		/* If more outstanding DMAs, queue the work.
+		 * Handle upend_idx wrap around
+		 */
+		if (unlikely((nvq->upend_idx + vq->num - VHOST_MAX_PEND)
+			      % UIO_MAXIOV == nvq->done_idx))
+			break;
+
+		head = vhost_get_vq_desc(vq, vq->iov,
+					 ARRAY_SIZE(vq->iov),
+					 &out, &in,
+					 NULL, NULL);
+		/* On error, stop handling until the next kick. */
+		if (unlikely(head < 0))
+			break;
+		/* Nothing new?  Wait for eventfd to tell us they refilled. */
+		if (head == vq->num) {
+			if (unlikely(vhost_enable_notify(&net->dev, vq))) {
+				vhost_disable_notify(&net->dev, vq);
+				continue;
+			}
+			break;
+		}
+		if (in) {
+			vq_err(vq, "Unexpected descriptor format for TX: "
+			       "out %d, int %d\n", out, in);
+			break;
+		}
+		/* Skip header. TODO: support TSO. */
+		len = iov_length(vq->iov, out);
+		iov_iter_init(&msg.msg_iter, WRITE, vq->iov, out, len);
+		iov_iter_advance(&msg.msg_iter, hdr_size);
+		/* Sanity check */
+		if (!msg_data_left(&msg)) {
+			vq_err(vq, "Unexpected header len for TX: "
+			       "%zd expected %zd\n",
+			       len, hdr_size);
+			break;
+		}
+		len = msg_data_left(&msg);
+
+		zcopy_used = zcopy && len >= VHOST_GOODCOPY_LEN
+				   && (nvq->upend_idx + 1) % UIO_MAXIOV !=
+				      nvq->done_idx
+				   && vhost_net_tx_select_zcopy(net);
+
+		/* use msg_control to pass vhost zerocopy ubuf info to skb */
+		if (zcopy_used) {
+			struct ubuf_info *ubuf;
+			ubuf = nvq->ubuf_info + nvq->upend_idx;
+
+			vq->heads[nvq->upend_idx].id = cpu_to_vhost32(vq, head);
+			vq->heads[nvq->upend_idx].len = VHOST_DMA_IN_PROGRESS;
+			ubuf->callback = vhost_zerocopy_callback;
+			ubuf->ctx = nvq->ubufs;
+			ubuf->desc = nvq->upend_idx;
+			msg.msg_control = ubuf;
+			msg.msg_controllen = sizeof(ubuf);
+			ubufs = nvq->ubufs;
+			atomic_inc(&ubufs->refcount);
+			nvq->upend_idx = (nvq->upend_idx + 1) % UIO_MAXIOV;
+		} else {
+			msg.msg_control = NULL;
+			ubufs = NULL;
+		}
+		/* TODO: Check specific error and bomb out unless ENOBUFS? */
+		err = sock->ops->sendmsg(sock, &msg, len);
+		if (unlikely(err < 0)) {
+			if (zcopy_used) {
+				vhost_net_ubuf_put(ubufs);
+				nvq->upend_idx = ((unsigned)nvq->upend_idx - 1)
+					% UIO_MAXIOV;
+			}
+			vhost_discard_vq_desc(vq, 1);
+			break;
+		}
+		if (err != len)
+			pr_debug("Truncated TX packet: "
+				 " len %d != %zd\n", err, len);
+		if (!zcopy_used)
+			vhost_add_used_and_signal(&net->dev, vq, head, 0);
+		else
+			vhost_zerocopy_signal_used(net, vq);
+		total_len += len;
+		vhost_net_tx_packet(net);
+		if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
+			vhost_poll_queue(&vq->poll);
+			break;
+		}
+	}
+out:
+	mutex_unlock(&vq->mutex);
+}
+
+static int peek_head_len(struct sock *sk)
+{
+	struct sk_buff *head;
+	int len = 0;
+	unsigned long flags;
+
+	spin_lock_irqsave(&sk->sk_receive_queue.lock, flags);
+	head = skb_peek(&sk->sk_receive_queue);
+	if (likely(head)) {
+		len = head->len;
+		if (skb_vlan_tag_present(head))
+			len += VLAN_HLEN;
+	}
+
+	spin_unlock_irqrestore(&sk->sk_receive_queue.lock, flags);
+	return len;
+}
+
+/* This is a multi-buffer version of vhost_get_desc, that works if
+ *	vq has read descriptors only.
+ * @vq		- the relevant virtqueue
+ * @datalen	- data length we'll be reading
+ * @iovcount	- returned count of io vectors we fill
+ * @log		- vhost log
+ * @log_num	- log offset
+ * @quota       - headcount quota, 1 for big buffer
+ *	returns number of buffer heads allocated, negative on error
+ */
+static int get_rx_bufs(struct vhost_virtqueue *vq,
+		       struct vring_used_elem *heads,
+		       int datalen,
+		       unsigned *iovcount,
+		       struct vhost_log *log,
+		       unsigned *log_num,
+		       unsigned int quota)
+{
+	unsigned int out, in;
+	int seg = 0;
+	int headcount = 0;
+	unsigned d;
+	int r, nlogs = 0;
+	/* len is always initialized before use since we are always called with
+	 * datalen > 0.
+	 */
+	u32 uninitialized_var(len);
+
+	while (datalen > 0 && headcount < quota) {
+		if (unlikely(seg >= UIO_MAXIOV)) {
+			r = -ENOBUFS;
+			goto err;
+		}
+		r = vhost_get_vq_desc(vq, vq->iov + seg,
+				      ARRAY_SIZE(vq->iov) - seg, &out,
+				      &in, log, log_num);
+		if (unlikely(r < 0))
+			goto err;
+
+		d = r;
+		if (d == vq->num) {
+			r = 0;
+			goto err;
+		}
+		if (unlikely(out || in <= 0)) {
+			vq_err(vq, "unexpected descriptor format for RX: "
+				"out %d, in %d\n", out, in);
+			r = -EINVAL;
+			goto err;
+		}
+		if (unlikely(log)) {
+			nlogs += *log_num;
+			log += *log_num;
+		}
+		heads[headcount].id = cpu_to_vhost32(vq, d);
+		len = iov_length(vq->iov + seg, in);
+		heads[headcount].len = cpu_to_vhost32(vq, len);
+		datalen -= len;
+		++headcount;
+		seg += in;
+	}
+	heads[headcount - 1].len = cpu_to_vhost32(vq, len + datalen);
+	*iovcount = seg;
+	if (unlikely(log))
+		*log_num = nlogs;
+
+	/* Detect overrun */
+	if (unlikely(datalen > 0)) {
+		r = UIO_MAXIOV + 1;
+		goto err;
+	}
+	return headcount;
+err:
+	vhost_discard_vq_desc(vq, headcount);
+	return r;
+}
+
+/* Expects to be always run from workqueue - which acts as
+ * read-size critical section for our kind of RCU. */
+static void handle_rx(struct vhost_net *net)
+{
+	struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_RX];
+	struct vhost_virtqueue *vq = &nvq->vq;
+	unsigned uninitialized_var(in), log;
+	struct vhost_log *vq_log;
+	struct msghdr msg = {
+		.msg_name = NULL,
+		.msg_namelen = 0,
+		.msg_control = NULL, /* FIXME: get and handle RX aux data. */
+		.msg_controllen = 0,
+		.msg_flags = MSG_DONTWAIT,
+	};
+	struct virtio_net_hdr hdr = {
+		.flags = 0,
+		.gso_type = VIRTIO_NET_HDR_GSO_NONE
+	};
+	size_t total_len = 0;
+	int err, mergeable;
+	s16 headcount;
+	size_t vhost_hlen, sock_hlen;
+	size_t vhost_len, sock_len;
+	struct socket *sock;
+	struct iov_iter fixup;
+	__virtio16 num_buffers;
+
+	mutex_lock(&vq->mutex);
+	sock = vq->private_data;
+	if (!sock)
+		goto out;
+	vhost_disable_notify(&net->dev, vq);
+
+	vhost_hlen = nvq->vhost_hlen;
+	sock_hlen = nvq->sock_hlen;
+
+	vq_log = unlikely(vhost_has_feature(vq, VHOST_F_LOG_ALL)) ?
+		vq->log : NULL;
+	mergeable = vhost_has_feature(vq, VIRTIO_NET_F_MRG_RXBUF);
+
+	while ((sock_len = peek_head_len(sock->sk))) {
+		sock_len += sock_hlen;
+		vhost_len = sock_len + vhost_hlen;
+		headcount = get_rx_bufs(vq, vq->heads, vhost_len,
+					&in, vq_log, &log,
+					likely(mergeable) ? UIO_MAXIOV : 1);
+		/* On error, stop handling until the next kick. */
+		if (unlikely(headcount < 0))
+			break;
+		/* On overrun, truncate and discard */
+		if (unlikely(headcount > UIO_MAXIOV)) {
+			iov_iter_init(&msg.msg_iter, READ, vq->iov, 1, 1);
+			err = sock->ops->recvmsg(sock, &msg,
+						 1, MSG_DONTWAIT | MSG_TRUNC);
+			pr_debug("Discarded rx packet: len %zd\n", sock_len);
+			continue;
+		}
+		/* OK, now we need to know about added descriptors. */
+		if (!headcount) {
+			if (unlikely(vhost_enable_notify(&net->dev, vq))) {
+				/* They have slipped one in as we were
+				 * doing that: check again. */
+				vhost_disable_notify(&net->dev, vq);
+				continue;
+			}
+			/* Nothing new?  Wait for eventfd to tell us
+			 * they refilled. */
+			break;
+		}
+		/* We don't need to be notified again. */
+		iov_iter_init(&msg.msg_iter, READ, vq->iov, in, vhost_len);
+		fixup = msg.msg_iter;
+		if (unlikely((vhost_hlen))) {
+			/* We will supply the header ourselves
+			 * TODO: support TSO.
+			 */
+			iov_iter_advance(&msg.msg_iter, vhost_hlen);
+		}
+		err = sock->ops->recvmsg(sock, &msg,
+					 sock_len, MSG_DONTWAIT | MSG_TRUNC);
+		/* Userspace might have consumed the packet meanwhile:
+		 * it's not supposed to do this usually, but might be hard
+		 * to prevent. Discard data we got (if any) and keep going. */
+		if (unlikely(err != sock_len)) {
+			pr_debug("Discarded rx packet: "
+				 " len %d, expected %zd\n", err, sock_len);
+			vhost_discard_vq_desc(vq, headcount);
+			continue;
+		}
+		/* Supply virtio_net_hdr if VHOST_NET_F_VIRTIO_NET_HDR */
+		if (unlikely(vhost_hlen)) {
+			if (copy_to_iter(&hdr, sizeof(hdr),
+					 &fixup) != sizeof(hdr)) {
+				vq_err(vq, "Unable to write vnet_hdr "
+				       "at addr %p\n", vq->iov->iov_base);
+				break;
+			}
+		} else {
+			/* Header came from socket; we'll need to patch
+			 * ->num_buffers over if VIRTIO_NET_F_MRG_RXBUF
+			 */
+			iov_iter_advance(&fixup, sizeof(hdr));
+		}
+		/* TODO: Should check and handle checksum. */
+
+		num_buffers = cpu_to_vhost16(vq, headcount);
+		if (likely(mergeable) &&
+		    copy_to_iter(&num_buffers, sizeof num_buffers,
+				 &fixup) != sizeof num_buffers) {
+			vq_err(vq, "Failed num_buffers write");
+			vhost_discard_vq_desc(vq, headcount);
+			break;
+		}
+		vhost_add_used_and_signal_n(&net->dev, vq, vq->heads,
+					    headcount);
+		if (unlikely(vq_log))
+			vhost_log_write(vq, vq_log, log, vhost_len);
+		total_len += vhost_len;
+		if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
+			vhost_poll_queue(&vq->poll);
+			break;
+		}
+	}
+out:
+	mutex_unlock(&vq->mutex);
+}
+
+static void handle_tx_kick(struct vhost_work *work)
+{
+	struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
+						  poll.work);
+	struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
+
+	handle_tx(net);
+}
+
+static void handle_rx_kick(struct vhost_work *work)
+{
+	struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
+						  poll.work);
+	struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
+
+	handle_rx(net);
+}
+
+static void handle_tx_net(struct vhost_work *work)
+{
+	struct vhost_net *net = container_of(work, struct vhost_net,
+					     poll[VHOST_NET_VQ_TX].work);
+	handle_tx(net);
+}
+
+static void handle_rx_net(struct vhost_work *work)
+{
+	struct vhost_net *net = container_of(work, struct vhost_net,
+					     poll[VHOST_NET_VQ_RX].work);
+	handle_rx(net);
+}
+
+static int vhost_net_open(struct inode *inode, struct file *f)
+{
+	struct vhost_net *n;
+	struct vhost_dev *dev;
+	struct vhost_virtqueue **vqs;
+	int i;
+
+	n = kmalloc(sizeof *n, GFP_KERNEL | __GFP_NOWARN | __GFP_REPEAT);
+	if (!n) {
+		n = vmalloc(sizeof *n);
+		if (!n)
+			return -ENOMEM;
+	}
+	vqs = kmalloc(VHOST_NET_VQ_MAX * sizeof(*vqs), GFP_KERNEL);
+	if (!vqs) {
+		kvfree(n);
+		return -ENOMEM;
+	}
+
+	dev = &n->dev;
+	vqs[VHOST_NET_VQ_TX] = &n->vqs[VHOST_NET_VQ_TX].vq;
+	vqs[VHOST_NET_VQ_RX] = &n->vqs[VHOST_NET_VQ_RX].vq;
+	n->vqs[VHOST_NET_VQ_TX].vq.handle_kick = handle_tx_kick;
+	n->vqs[VHOST_NET_VQ_RX].vq.handle_kick = handle_rx_kick;
+	for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
+		n->vqs[i].ubufs = NULL;
+		n->vqs[i].ubuf_info = NULL;
+		n->vqs[i].upend_idx = 0;
+		n->vqs[i].done_idx = 0;
+		n->vqs[i].vhost_hlen = 0;
+		n->vqs[i].sock_hlen = 0;
+	}
+	vhost_dev_init(dev, vqs, VHOST_NET_VQ_MAX);
+
+	vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, POLLOUT, dev);
+	vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, POLLIN, dev);
+
+	f->private_data = n;
+
+	return 0;
+}
+
+static void vhost_net_disable_vq(struct vhost_net *n,
+				 struct vhost_virtqueue *vq)
+{
+	struct vhost_net_virtqueue *nvq =
+		container_of(vq, struct vhost_net_virtqueue, vq);
+	struct vhost_poll *poll = n->poll + (nvq - n->vqs);
+	if (!vq->private_data)
+		return;
+	vhost_poll_stop(poll);
+}
+
+static int vhost_net_enable_vq(struct vhost_net *n,
+				struct vhost_virtqueue *vq)
+{
+	struct vhost_net_virtqueue *nvq =
+		container_of(vq, struct vhost_net_virtqueue, vq);
+	struct vhost_poll *poll = n->poll + (nvq - n->vqs);
+	struct socket *sock;
+
+	sock = vq->private_data;
+	if (!sock)
+		return 0;
+
+	return vhost_poll_start(poll, sock->file);
+}
+
+static struct socket *vhost_net_stop_vq(struct vhost_net *n,
+					struct vhost_virtqueue *vq)
+{
+	struct socket *sock;
+
+	mutex_lock(&vq->mutex);
+	sock = vq->private_data;
+	vhost_net_disable_vq(n, vq);
+	vq->private_data = NULL;
+	mutex_unlock(&vq->mutex);
+	return sock;
+}
+
+static void vhost_net_stop(struct vhost_net *n, struct socket **tx_sock,
+			   struct socket **rx_sock)
+{
+	*tx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_TX].vq);
+	*rx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_RX].vq);
+}
+
+static void vhost_net_flush_vq(struct vhost_net *n, int index)
+{
+	vhost_poll_flush(n->poll + index);
+	vhost_poll_flush(&n->vqs[index].vq.poll);
+}
+
+static void vhost_net_flush(struct vhost_net *n)
+{
+	vhost_net_flush_vq(n, VHOST_NET_VQ_TX);
+	vhost_net_flush_vq(n, VHOST_NET_VQ_RX);
+	if (n->vqs[VHOST_NET_VQ_TX].ubufs) {
+		mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
+		n->tx_flush = true;
+		mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
+		/* Wait for all lower device DMAs done. */
+		vhost_net_ubuf_put_and_wait(n->vqs[VHOST_NET_VQ_TX].ubufs);
+		mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
+		n->tx_flush = false;
+		atomic_set(&n->vqs[VHOST_NET_VQ_TX].ubufs->refcount, 1);
+		mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
+	}
+}
+
+static int vhost_net_release(struct inode *inode, struct file *f)
+{
+	struct vhost_net *n = f->private_data;
+	struct socket *tx_sock;
+	struct socket *rx_sock;
+
+	vhost_net_stop(n, &tx_sock, &rx_sock);
+	vhost_net_flush(n);
+	vhost_dev_stop(&n->dev);
+	vhost_dev_cleanup(&n->dev, false);
+	vhost_net_vq_reset(n);
+	if (tx_sock)
+		sockfd_put(tx_sock);
+	if (rx_sock)
+		sockfd_put(rx_sock);
+	/* Make sure no callbacks are outstanding */
+	synchronize_rcu_bh();
+	/* We do an extra flush before freeing memory,
+	 * since jobs can re-queue themselves. */
+	vhost_net_flush(n);
+	kfree(n->dev.vqs);
+	kvfree(n);
+	return 0;
+}
+
+static struct socket *get_raw_socket(int fd)
+{
+	struct {
+		struct sockaddr_ll sa;
+		char  buf[MAX_ADDR_LEN];
+	} uaddr;
+	int uaddr_len = sizeof uaddr, r;
+	struct socket *sock = sockfd_lookup(fd, &r);
+
+	if (!sock)
+		return ERR_PTR(-ENOTSOCK);
+
+	/* Parameter checking */
+	if (sock->sk->sk_type != SOCK_RAW) {
+		r = -ESOCKTNOSUPPORT;
+		goto err;
+	}
+
+	r = sock->ops->getname(sock, (struct sockaddr *)&uaddr.sa,
+			       &uaddr_len, 0);
+	if (r)
+		goto err;
+
+	if (uaddr.sa.sll_family != AF_PACKET) {
+		r = -EPFNOSUPPORT;
+		goto err;
+	}
+	return sock;
+err:
+	sockfd_put(sock);
+	return ERR_PTR(r);
+}
+
+static struct socket *get_tap_socket(int fd)
+{
+	struct file *file = fget(fd);
+	struct socket *sock;
+
+	if (!file)
+		return ERR_PTR(-EBADF);
+	sock = tun_get_socket(file);
+	if (!IS_ERR(sock))
+		return sock;
+	sock = macvtap_get_socket(file);
+	if (IS_ERR(sock))
+		fput(file);
+	return sock;
+}
+
+static struct socket *get_socket(int fd)
+{
+	struct socket *sock;
+
+	/* special case to disable backend */
+	if (fd == -1)
+		return NULL;
+	sock = get_raw_socket(fd);
+	if (!IS_ERR(sock))
+		return sock;
+	sock = get_tap_socket(fd);
+	if (!IS_ERR(sock))
+		return sock;
+	return ERR_PTR(-ENOTSOCK);
+}
+
+static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
+{
+	struct socket *sock, *oldsock;
+	struct vhost_virtqueue *vq;
+	struct vhost_net_virtqueue *nvq;
+	struct vhost_net_ubuf_ref *ubufs, *oldubufs = NULL;
+	int r;
+
+	mutex_lock(&n->dev.mutex);
+	r = vhost_dev_check_owner(&n->dev);
+	if (r)
+		goto err;
+
+	if (index >= VHOST_NET_VQ_MAX) {
+		r = -ENOBUFS;
+		goto err;
+	}
+	vq = &n->vqs[index].vq;
+	nvq = &n->vqs[index];
+	mutex_lock(&vq->mutex);
+
+	/* Verify that ring has been setup correctly. */
+	if (!vhost_vq_access_ok(vq)) {
+		r = -EFAULT;
+		goto err_vq;
+	}
+	sock = get_socket(fd);
+	if (IS_ERR(sock)) {
+		r = PTR_ERR(sock);
+		goto err_vq;
+	}
+
+	/* start polling new socket */
+	oldsock = vq->private_data;
+	if (sock != oldsock) {
+		ubufs = vhost_net_ubuf_alloc(vq,
+					     sock && vhost_sock_zcopy(sock));
+		if (IS_ERR(ubufs)) {
+			r = PTR_ERR(ubufs);
+			goto err_ubufs;
+		}
+
+		vhost_net_disable_vq(n, vq);
+		vq->private_data = sock;
+		r = vhost_init_used(vq);
+		if (r)
+			goto err_used;
+		r = vhost_net_enable_vq(n, vq);
+		if (r)
+			goto err_used;
+
+		oldubufs = nvq->ubufs;
+		nvq->ubufs = ubufs;
+
+		n->tx_packets = 0;
+		n->tx_zcopy_err = 0;
+		n->tx_flush = false;
+	}
+
+	mutex_unlock(&vq->mutex);
+
+	if (oldubufs) {
+		vhost_net_ubuf_put_wait_and_free(oldubufs);
+		mutex_lock(&vq->mutex);
+		vhost_zerocopy_signal_used(n, vq);
+		mutex_unlock(&vq->mutex);
+	}
+
+	if (oldsock) {
+		vhost_net_flush_vq(n, index);
+		sockfd_put(oldsock);
+	}
+
+	mutex_unlock(&n->dev.mutex);
+	return 0;
+
+err_used:
+	vq->private_data = oldsock;
+	vhost_net_enable_vq(n, vq);
+	if (ubufs)
+		vhost_net_ubuf_put_wait_and_free(ubufs);
+err_ubufs:
+	sockfd_put(sock);
+err_vq:
+	mutex_unlock(&vq->mutex);
+err:
+	mutex_unlock(&n->dev.mutex);
+	return r;
+}
+
+static long vhost_net_reset_owner(struct vhost_net *n)
+{
+	struct socket *tx_sock = NULL;
+	struct socket *rx_sock = NULL;
+	long err;
+	struct vhost_memory *memory;
+
+	mutex_lock(&n->dev.mutex);
+	err = vhost_dev_check_owner(&n->dev);
+	if (err)
+		goto done;
+	memory = vhost_dev_reset_owner_prepare();
+	if (!memory) {
+		err = -ENOMEM;
+		goto done;
+	}
+	vhost_net_stop(n, &tx_sock, &rx_sock);
+	vhost_net_flush(n);
+	vhost_dev_reset_owner(&n->dev, memory);
+	vhost_net_vq_reset(n);
+done:
+	mutex_unlock(&n->dev.mutex);
+	if (tx_sock)
+		sockfd_put(tx_sock);
+	if (rx_sock)
+		sockfd_put(rx_sock);
+	return err;
+}
+
+static int vhost_net_set_features(struct vhost_net *n, u64 features)
+{
+	size_t vhost_hlen, sock_hlen, hdr_len;
+	int i;
+
+	hdr_len = (features & ((1ULL << VIRTIO_NET_F_MRG_RXBUF) |
+			       (1ULL << VIRTIO_F_VERSION_1))) ?
+			sizeof(struct virtio_net_hdr_mrg_rxbuf) :
+			sizeof(struct virtio_net_hdr);
+	if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
+		/* vhost provides vnet_hdr */
+		vhost_hlen = hdr_len;
+		sock_hlen = 0;
+	} else {
+		/* socket provides vnet_hdr */
+		vhost_hlen = 0;
+		sock_hlen = hdr_len;
+	}
+	mutex_lock(&n->dev.mutex);
+	if ((features & (1 << VHOST_F_LOG_ALL)) &&
+	    !vhost_log_access_ok(&n->dev)) {
+		mutex_unlock(&n->dev.mutex);
+		return -EFAULT;
+	}
+	for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
+		mutex_lock(&n->vqs[i].vq.mutex);
+		n->vqs[i].vq.acked_features = features;
+		n->vqs[i].vhost_hlen = vhost_hlen;
+		n->vqs[i].sock_hlen = sock_hlen;
+		mutex_unlock(&n->vqs[i].vq.mutex);
+	}
+	mutex_unlock(&n->dev.mutex);
+	return 0;
+}
+
+static long vhost_net_set_owner(struct vhost_net *n)
+{
+	int r;
+
+	mutex_lock(&n->dev.mutex);
+	if (vhost_dev_has_owner(&n->dev)) {
+		r = -EBUSY;
+		goto out;
+	}
+	r = vhost_net_set_ubuf_info(n);
+	if (r)
+		goto out;
+	r = vhost_dev_set_owner(&n->dev);
+	if (r)
+		vhost_net_clear_ubuf_info(n);
+	vhost_net_flush(n);
+out:
+	mutex_unlock(&n->dev.mutex);
+	return r;
+}
+
+static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
+			    unsigned long arg)
+{
+	struct vhost_net *n = f->private_data;
+	void __user *argp = (void __user *)arg;
+	u64 __user *featurep = argp;
+	struct vhost_vring_file backend;
+	u64 features;
+	int r;
+
+	switch (ioctl) {
+	case VHOST_NET_SET_BACKEND:
+		if (copy_from_user(&backend, argp, sizeof backend))
+			return -EFAULT;
+		return vhost_net_set_backend(n, backend.index, backend.fd);
+	case VHOST_GET_FEATURES:
+		features = VHOST_NET_FEATURES;
+		if (copy_to_user(featurep, &features, sizeof features))
+			return -EFAULT;
+		return 0;
+	case VHOST_SET_FEATURES:
+		if (copy_from_user(&features, featurep, sizeof features))
+			return -EFAULT;
+		if (features & ~VHOST_NET_FEATURES)
+			return -EOPNOTSUPP;
+		return vhost_net_set_features(n, features);
+	case VHOST_RESET_OWNER:
+		return vhost_net_reset_owner(n);
+	case VHOST_SET_OWNER:
+		return vhost_net_set_owner(n);
+	default:
+		mutex_lock(&n->dev.mutex);
+		r = vhost_dev_ioctl(&n->dev, ioctl, argp);
+		if (r == -ENOIOCTLCMD)
+			r = vhost_vring_ioctl(&n->dev, ioctl, argp);
+		else
+			vhost_net_flush(n);
+		mutex_unlock(&n->dev.mutex);
+		return r;
+	}
+}
+
+#ifdef CONFIG_COMPAT
+static long vhost_net_compat_ioctl(struct file *f, unsigned int ioctl,
+				   unsigned long arg)
+{
+	return vhost_net_ioctl(f, ioctl, (unsigned long)compat_ptr(arg));
+}
+#endif
+
+static const struct file_operations vhost_net_fops = {
+	.owner          = THIS_MODULE,
+	.release        = vhost_net_release,
+	.unlocked_ioctl = vhost_net_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl   = vhost_net_compat_ioctl,
+#endif
+	.open           = vhost_net_open,
+	.llseek		= noop_llseek,
+};
+
+static struct miscdevice vhost_net_misc = {
+	.minor = VHOST_NET_MINOR,
+	.name = "vhost-net",
+	.fops = &vhost_net_fops,
+};
+
+static int vhost_net_init(void)
+{
+	if (experimental_zcopytx)
+		vhost_net_enable_zcopy(VHOST_NET_VQ_TX);
+	return misc_register(&vhost_net_misc);
+}
+module_init(vhost_net_init);
+
+static void vhost_net_exit(void)
+{
+	misc_deregister(&vhost_net_misc);
+}
+module_exit(vhost_net_exit);
+
+MODULE_VERSION("0.0.1");
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Michael S. Tsirkin");
+MODULE_DESCRIPTION("Host kernel accelerator for virtio net");
+MODULE_ALIAS_MISCDEV(VHOST_NET_MINOR);
+MODULE_ALIAS("devname:vhost-net");