Initial import

1 files changed, 651 insertions, 0 deletions

diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
new file mode 100644
index 000000000..fd933695f
--- /dev/null
+++ b/drivers/xen/balloon.c
@@ -0,0 +1,651 @@
+/******************************************************************************
+ * Xen balloon driver - enables returning/claiming memory to/from Xen.
+ *
+ * Copyright (c) 2003, B Dragovic
+ * Copyright (c) 2003-2004, M Williamson, K Fraser
+ * Copyright (c) 2005 Dan M. Smith, IBM Corporation
+ * Copyright (c) 2010 Daniel Kiper
+ *
+ * Memory hotplug support was written by Daniel Kiper. Work on
+ * it was sponsored by Google under Google Summer of Code 2010
+ * program. Jeremy Fitzhardinge from Citrix was the mentor for
+ * this project.
+ *
+ * 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; or, when distributed
+ * separately from the Linux kernel or incorporated into other
+ * software packages, subject to the following license:
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this source file (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy, modify,
+ * merge, publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
+
+#include <linux/cpu.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/errno.h>
+#include <linux/module.h>
+#include <linux/mm.h>
+#include <linux/bootmem.h>
+#include <linux/pagemap.h>
+#include <linux/highmem.h>
+#include <linux/mutex.h>
+#include <linux/list.h>
+#include <linux/gfp.h>
+#include <linux/notifier.h>
+#include <linux/memory.h>
+#include <linux/memory_hotplug.h>
+#include <linux/percpu-defs.h>
+
+#include <asm/page.h>
+#include <asm/pgalloc.h>
+#include <asm/pgtable.h>
+#include <asm/tlb.h>
+
+#include <asm/xen/hypervisor.h>
+#include <asm/xen/hypercall.h>
+
+#include <xen/xen.h>
+#include <xen/interface/xen.h>
+#include <xen/interface/memory.h>
+#include <xen/balloon.h>
+#include <xen/features.h>
+#include <xen/page.h>
+
+/*
+ * balloon_process() state:
+ *
+ * BP_DONE: done or nothing to do,
+ * BP_EAGAIN: error, go to sleep,
+ * BP_ECANCELED: error, balloon operation canceled.
+ */
+
+enum bp_state {
+	BP_DONE,
+	BP_EAGAIN,
+	BP_ECANCELED
+};
+
+
+static DEFINE_MUTEX(balloon_mutex);
+
+struct balloon_stats balloon_stats;
+EXPORT_SYMBOL_GPL(balloon_stats);
+
+/* We increase/decrease in batches which fit in a page */
+static xen_pfn_t frame_list[PAGE_SIZE / sizeof(unsigned long)];
+
+
+/* List of ballooned pages, threaded through the mem_map array. */
+static LIST_HEAD(ballooned_pages);
+
+/* Main work function, always executed in process context. */
+static void balloon_process(struct work_struct *work);
+static DECLARE_DELAYED_WORK(balloon_worker, balloon_process);
+
+/* When ballooning out (allocating memory to return to Xen) we don't really
+   want the kernel to try too hard since that can trigger the oom killer. */
+#define GFP_BALLOON \
+	(GFP_HIGHUSER | __GFP_NOWARN | __GFP_NORETRY | __GFP_NOMEMALLOC)
+
+static void scrub_page(struct page *page)
+{
+#ifdef CONFIG_XEN_SCRUB_PAGES
+	clear_highpage(page);
+#endif
+}
+
+/* balloon_append: add the given page to the balloon. */
+static void __balloon_append(struct page *page)
+{
+	/* Lowmem is re-populated first, so highmem pages go at list tail. */
+	if (PageHighMem(page)) {
+		list_add_tail(&page->lru, &ballooned_pages);
+		balloon_stats.balloon_high++;
+	} else {
+		list_add(&page->lru, &ballooned_pages);
+		balloon_stats.balloon_low++;
+	}
+}
+
+static void balloon_append(struct page *page)
+{
+	__balloon_append(page);
+	adjust_managed_page_count(page, -1);
+}
+
+/* balloon_retrieve: rescue a page from the balloon, if it is not empty. */
+static struct page *balloon_retrieve(bool prefer_highmem)
+{
+	struct page *page;
+
+	if (list_empty(&ballooned_pages))
+		return NULL;
+
+	if (prefer_highmem)
+		page = list_entry(ballooned_pages.prev, struct page, lru);
+	else
+		page = list_entry(ballooned_pages.next, struct page, lru);
+	list_del(&page->lru);
+
+	if (PageHighMem(page))
+		balloon_stats.balloon_high--;
+	else
+		balloon_stats.balloon_low--;
+
+	adjust_managed_page_count(page, 1);
+
+	return page;
+}
+
+static struct page *balloon_next_page(struct page *page)
+{
+	struct list_head *next = page->lru.next;
+	if (next == &ballooned_pages)
+		return NULL;
+	return list_entry(next, struct page, lru);
+}
+
+static enum bp_state update_schedule(enum bp_state state)
+{
+	if (state == BP_ECANCELED)
+		return BP_ECANCELED;
+
+	if (state == BP_DONE) {
+		balloon_stats.schedule_delay = 1;
+		balloon_stats.retry_count = 1;
+		return BP_DONE;
+	}
+
+	++balloon_stats.retry_count;
+
+	if (balloon_stats.max_retry_count != RETRY_UNLIMITED &&
+			balloon_stats.retry_count > balloon_stats.max_retry_count) {
+		balloon_stats.schedule_delay = 1;
+		balloon_stats.retry_count = 1;
+		return BP_ECANCELED;
+	}
+
+	balloon_stats.schedule_delay <<= 1;
+
+	if (balloon_stats.schedule_delay > balloon_stats.max_schedule_delay)
+		balloon_stats.schedule_delay = balloon_stats.max_schedule_delay;
+
+	return BP_EAGAIN;
+}
+
+#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
+static long current_credit(void)
+{
+	return balloon_stats.target_pages - balloon_stats.current_pages -
+		balloon_stats.hotplug_pages;
+}
+
+static bool balloon_is_inflated(void)
+{
+	if (balloon_stats.balloon_low || balloon_stats.balloon_high ||
+			balloon_stats.balloon_hotplug)
+		return true;
+	else
+		return false;
+}
+
+/*
+ * reserve_additional_memory() adds memory region of size >= credit above
+ * max_pfn. New region is section aligned and size is modified to be multiple
+ * of section size. Those features allow optimal use of address space and
+ * establish proper alignment when this function is called first time after
+ * boot (last section not fully populated at boot time contains unused memory
+ * pages with PG_reserved bit not set; online_pages_range() does not allow page
+ * onlining in whole range if first onlined page does not have PG_reserved
+ * bit set). Real size of added memory is established at page onlining stage.
+ */
+
+static enum bp_state reserve_additional_memory(long credit)
+{
+	int nid, rc;
+	u64 hotplug_start_paddr;
+	unsigned long balloon_hotplug = credit;
+
+	hotplug_start_paddr = PFN_PHYS(SECTION_ALIGN_UP(max_pfn));
+	balloon_hotplug = round_up(balloon_hotplug, PAGES_PER_SECTION);
+	nid = memory_add_physaddr_to_nid(hotplug_start_paddr);
+
+#ifdef CONFIG_XEN_HAVE_PVMMU
+        /*
+         * add_memory() will build page tables for the new memory so
+         * the p2m must contain invalid entries so the correct
+         * non-present PTEs will be written.
+         *
+         * If a failure occurs, the original (identity) p2m entries
+         * are not restored since this region is now known not to
+         * conflict with any devices.
+         */ 
+	if (!xen_feature(XENFEAT_auto_translated_physmap)) {
+		unsigned long pfn, i;
+
+		pfn = PFN_DOWN(hotplug_start_paddr);
+		for (i = 0; i < balloon_hotplug; i++) {
+			if (!set_phys_to_machine(pfn + i, INVALID_P2M_ENTRY)) {
+				pr_warn("set_phys_to_machine() failed, no memory added\n");
+				return BP_ECANCELED;
+			}
+                }
+	}
+#endif
+
+	rc = add_memory(nid, hotplug_start_paddr, balloon_hotplug << PAGE_SHIFT);
+
+	if (rc) {
+		pr_warn("Cannot add additional memory (%i)\n", rc);
+		return BP_ECANCELED;
+	}
+
+	balloon_hotplug -= credit;
+
+	balloon_stats.hotplug_pages += credit;
+	balloon_stats.balloon_hotplug = balloon_hotplug;
+
+	return BP_DONE;
+}
+
+static void xen_online_page(struct page *page)
+{
+	__online_page_set_limits(page);
+
+	mutex_lock(&balloon_mutex);
+
+	__balloon_append(page);
+
+	if (balloon_stats.hotplug_pages)
+		--balloon_stats.hotplug_pages;
+	else
+		--balloon_stats.balloon_hotplug;
+
+	mutex_unlock(&balloon_mutex);
+}
+
+static int xen_memory_notifier(struct notifier_block *nb, unsigned long val, void *v)
+{
+	if (val == MEM_ONLINE)
+		schedule_delayed_work(&balloon_worker, 0);
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block xen_memory_nb = {
+	.notifier_call = xen_memory_notifier,
+	.priority = 0
+};
+#else
+static long current_credit(void)
+{
+	unsigned long target = balloon_stats.target_pages;
+
+	target = min(target,
+		     balloon_stats.current_pages +
+		     balloon_stats.balloon_low +
+		     balloon_stats.balloon_high);
+
+	return target - balloon_stats.current_pages;
+}
+
+static bool balloon_is_inflated(void)
+{
+	if (balloon_stats.balloon_low || balloon_stats.balloon_high)
+		return true;
+	else
+		return false;
+}
+
+static enum bp_state reserve_additional_memory(long credit)
+{
+	balloon_stats.target_pages = balloon_stats.current_pages;
+	return BP_DONE;
+}
+#endif /* CONFIG_XEN_BALLOON_MEMORY_HOTPLUG */
+
+static enum bp_state increase_reservation(unsigned long nr_pages)
+{
+	int rc;
+	unsigned long  pfn, i;
+	struct page   *page;
+	struct xen_memory_reservation reservation = {
+		.address_bits = 0,
+		.extent_order = 0,
+		.domid        = DOMID_SELF
+	};
+
+#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
+	if (!balloon_stats.balloon_low && !balloon_stats.balloon_high) {
+		nr_pages = min(nr_pages, balloon_stats.balloon_hotplug);
+		balloon_stats.hotplug_pages += nr_pages;
+		balloon_stats.balloon_hotplug -= nr_pages;
+		return BP_DONE;
+	}
+#endif
+
+	if (nr_pages > ARRAY_SIZE(frame_list))
+		nr_pages = ARRAY_SIZE(frame_list);
+
+	page = list_first_entry_or_null(&ballooned_pages, struct page, lru);
+	for (i = 0; i < nr_pages; i++) {
+		if (!page) {
+			nr_pages = i;
+			break;
+		}
+		frame_list[i] = page_to_pfn(page);
+		page = balloon_next_page(page);
+	}
+
+	set_xen_guest_handle(reservation.extent_start, frame_list);
+	reservation.nr_extents = nr_pages;
+	rc = HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation);
+	if (rc <= 0)
+		return BP_EAGAIN;
+
+	for (i = 0; i < rc; i++) {
+		page = balloon_retrieve(false);
+		BUG_ON(page == NULL);
+
+		pfn = page_to_pfn(page);
+
+#ifdef CONFIG_XEN_HAVE_PVMMU
+		if (!xen_feature(XENFEAT_auto_translated_physmap)) {
+			set_phys_to_machine(pfn, frame_list[i]);
+
+			/* Link back into the page tables if not highmem. */
+			if (!PageHighMem(page)) {
+				int ret;
+				ret = HYPERVISOR_update_va_mapping(
+						(unsigned long)__va(pfn << PAGE_SHIFT),
+						mfn_pte(frame_list[i], PAGE_KERNEL),
+						0);
+				BUG_ON(ret);
+			}
+		}
+#endif
+
+		/* Relinquish the page back to the allocator. */
+		__free_reserved_page(page);
+	}
+
+	balloon_stats.current_pages += rc;
+
+	return BP_DONE;
+}
+
+static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
+{
+	enum bp_state state = BP_DONE;
+	unsigned long  pfn, i;
+	struct page   *page;
+	int ret;
+	struct xen_memory_reservation reservation = {
+		.address_bits = 0,
+		.extent_order = 0,
+		.domid        = DOMID_SELF
+	};
+
+#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
+	if (balloon_stats.hotplug_pages) {
+		nr_pages = min(nr_pages, balloon_stats.hotplug_pages);
+		balloon_stats.hotplug_pages -= nr_pages;
+		balloon_stats.balloon_hotplug += nr_pages;
+		return BP_DONE;
+	}
+#endif
+
+	if (nr_pages > ARRAY_SIZE(frame_list))
+		nr_pages = ARRAY_SIZE(frame_list);
+
+	for (i = 0; i < nr_pages; i++) {
+		page = alloc_page(gfp);
+		if (page == NULL) {
+			nr_pages = i;
+			state = BP_EAGAIN;
+			break;
+		}
+		scrub_page(page);
+
+		frame_list[i] = page_to_pfn(page);
+	}
+
+	/*
+	 * Ensure that ballooned highmem pages don't have kmaps.
+	 *
+	 * Do this before changing the p2m as kmap_flush_unused()
+	 * reads PTEs to obtain pages (and hence needs the original
+	 * p2m entry).
+	 */
+	kmap_flush_unused();
+
+	/* Update direct mapping, invalidate P2M, and add to balloon. */
+	for (i = 0; i < nr_pages; i++) {
+		pfn = frame_list[i];
+		frame_list[i] = pfn_to_mfn(pfn);
+		page = pfn_to_page(pfn);
+
+#ifdef CONFIG_XEN_HAVE_PVMMU
+		if (!xen_feature(XENFEAT_auto_translated_physmap)) {
+			if (!PageHighMem(page)) {
+				ret = HYPERVISOR_update_va_mapping(
+						(unsigned long)__va(pfn << PAGE_SHIFT),
+						__pte_ma(0), 0);
+				BUG_ON(ret);
+			}
+			__set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
+		}
+#endif
+
+		balloon_append(page);
+	}
+
+	flush_tlb_all();
+
+	set_xen_guest_handle(reservation.extent_start, frame_list);
+	reservation.nr_extents   = nr_pages;
+	ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation);
+	BUG_ON(ret != nr_pages);
+
+	balloon_stats.current_pages -= nr_pages;
+
+	return state;
+}
+
+/*
+ * We avoid multiple worker processes conflicting via the balloon mutex.
+ * We may of course race updates of the target counts (which are protected
+ * by the balloon lock), or with changes to the Xen hard limit, but we will
+ * recover from these in time.
+ */
+static void balloon_process(struct work_struct *work)
+{
+	enum bp_state state = BP_DONE;
+	long credit;
+
+	mutex_lock(&balloon_mutex);
+
+	do {
+		credit = current_credit();
+
+		if (credit > 0) {
+			if (balloon_is_inflated())
+				state = increase_reservation(credit);
+			else
+				state = reserve_additional_memory(credit);
+		}
+
+		if (credit < 0)
+			state = decrease_reservation(-credit, GFP_BALLOON);
+
+		state = update_schedule(state);
+
+#ifndef CONFIG_PREEMPT
+		if (need_resched())
+			schedule();
+#endif
+	} while (credit && state == BP_DONE);
+
+	/* Schedule more work if there is some still to be done. */
+	if (state == BP_EAGAIN)
+		schedule_delayed_work(&balloon_worker, balloon_stats.schedule_delay * HZ);
+
+	mutex_unlock(&balloon_mutex);
+}
+
+/* Resets the Xen limit, sets new target, and kicks off processing. */
+void balloon_set_new_target(unsigned long target)
+{
+	/* No need for lock. Not read-modify-write updates. */
+	balloon_stats.target_pages = target;
+	schedule_delayed_work(&balloon_worker, 0);
+}
+EXPORT_SYMBOL_GPL(balloon_set_new_target);
+
+/**
+ * alloc_xenballooned_pages - get pages that have been ballooned out
+ * @nr_pages: Number of pages to get
+ * @pages: pages returned
+ * @highmem: allow highmem pages
+ * @return 0 on success, error otherwise
+ */
+int alloc_xenballooned_pages(int nr_pages, struct page **pages, bool highmem)
+{
+	int pgno = 0;
+	struct page *page;
+	mutex_lock(&balloon_mutex);
+	while (pgno < nr_pages) {
+		page = balloon_retrieve(highmem);
+		if (page && (highmem || !PageHighMem(page))) {
+			pages[pgno++] = page;
+		} else {
+			enum bp_state st;
+			if (page)
+				balloon_append(page);
+			st = decrease_reservation(nr_pages - pgno,
+					highmem ? GFP_HIGHUSER : GFP_USER);
+			if (st != BP_DONE)
+				goto out_undo;
+		}
+	}
+	mutex_unlock(&balloon_mutex);
+	return 0;
+ out_undo:
+	while (pgno)
+		balloon_append(pages[--pgno]);
+	/* Free the memory back to the kernel soon */
+	schedule_delayed_work(&balloon_worker, 0);
+	mutex_unlock(&balloon_mutex);
+	return -ENOMEM;
+}
+EXPORT_SYMBOL(alloc_xenballooned_pages);
+
+/**
+ * free_xenballooned_pages - return pages retrieved with get_ballooned_pages
+ * @nr_pages: Number of pages
+ * @pages: pages to return
+ */
+void free_xenballooned_pages(int nr_pages, struct page **pages)
+{
+	int i;
+
+	mutex_lock(&balloon_mutex);
+
+	for (i = 0; i < nr_pages; i++) {
+		if (pages[i])
+			balloon_append(pages[i]);
+	}
+
+	/* The balloon may be too large now. Shrink it if needed. */
+	if (current_credit())
+		schedule_delayed_work(&balloon_worker, 0);
+
+	mutex_unlock(&balloon_mutex);
+}
+EXPORT_SYMBOL(free_xenballooned_pages);
+
+static void __init balloon_add_region(unsigned long start_pfn,
+				      unsigned long pages)
+{
+	unsigned long pfn, extra_pfn_end;
+	struct page *page;
+
+	/*
+	 * If the amount of usable memory has been limited (e.g., with
+	 * the 'mem' command line parameter), don't add pages beyond
+	 * this limit.
+	 */
+	extra_pfn_end = min(max_pfn, start_pfn + pages);
+
+	for (pfn = start_pfn; pfn < extra_pfn_end; pfn++) {
+		page = pfn_to_page(pfn);
+		/* totalram_pages and totalhigh_pages do not
+		   include the boot-time balloon extension, so
+		   don't subtract from it. */
+		__balloon_append(page);
+	}
+}
+
+static int __init balloon_init(void)
+{
+	int i;
+
+	if (!xen_domain())
+		return -ENODEV;
+
+	pr_info("Initialising balloon driver\n");
+
+	balloon_stats.current_pages = xen_pv_domain()
+		? min(xen_start_info->nr_pages - xen_released_pages, max_pfn)
+		: get_num_physpages();
+	balloon_stats.target_pages  = balloon_stats.current_pages;
+	balloon_stats.balloon_low   = 0;
+	balloon_stats.balloon_high  = 0;
+
+	balloon_stats.schedule_delay = 1;
+	balloon_stats.max_schedule_delay = 32;
+	balloon_stats.retry_count = 1;
+	balloon_stats.max_retry_count = RETRY_UNLIMITED;
+
+#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
+	balloon_stats.hotplug_pages = 0;
+	balloon_stats.balloon_hotplug = 0;
+
+	set_online_page_callback(&xen_online_page);
+	register_memory_notifier(&xen_memory_nb);
+#endif
+
+	/*
+	 * Initialize the balloon with pages from the extra memory
+	 * regions (see arch/x86/xen/setup.c).
+	 */
+	for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++)
+		if (xen_extra_mem[i].size)
+			balloon_add_region(PFN_UP(xen_extra_mem[i].start),
+					   PFN_DOWN(xen_extra_mem[i].size));
+
+	return 0;
+}
+
+subsys_initcall(balloon_init);
+
+MODULE_LICENSE("GPL");