virtio_balloon.c

   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * Virtio balloon implementation, inspired by Dor Laor and Marcelo
   4 * Tosatti's implementations.
   5 *
   6 *  Copyright 2008 Rusty Russell IBM Corporation
   7 */
   8
   9#include <linux/virtio.h>
  10#include <linux/virtio_balloon.h>
  11#include <linux/swap.h>
  12#include <linux/workqueue.h>
  13#include <linux/delay.h>
  14#include <linux/slab.h>
  15#include <linux/module.h>
  16#include <linux/balloon_compaction.h>
  17#include <linux/oom.h>
  18#include <linux/wait.h>
  19#include <linux/mm.h>
  20#include <linux/page_reporting.h>
  21
  22/*
  23 * Balloon device works in 4K page units.  So each page is pointed to by
  24 * multiple balloon pages.  All memory counters in this driver are in balloon
  25 * page units.
  26 */
  27#define VIRTIO_BALLOON_PAGES_PER_PAGE (unsigned int)(PAGE_SIZE >> VIRTIO_BALLOON_PFN_SHIFT)
  28#define VIRTIO_BALLOON_ARRAY_PFNS_MAX 256
  29/* Maximum number of (4k) pages to deflate on OOM notifications. */
  30#define VIRTIO_BALLOON_OOM_NR_PAGES 256
  31#define VIRTIO_BALLOON_OOM_NOTIFY_PRIORITY 80
  32
  33#define VIRTIO_BALLOON_FREE_PAGE_ALLOC_FLAG (__GFP_NORETRY | __GFP_NOWARN | \
  34					     __GFP_NOMEMALLOC)
  35/* The order of free page blocks to report to host */
  36#define VIRTIO_BALLOON_HINT_BLOCK_ORDER MAX_PAGE_ORDER
  37/* The size of a free page block in bytes */
  38#define VIRTIO_BALLOON_HINT_BLOCK_BYTES \
  39	(1 << (VIRTIO_BALLOON_HINT_BLOCK_ORDER + PAGE_SHIFT))
  40#define VIRTIO_BALLOON_HINT_BLOCK_PAGES (1 << VIRTIO_BALLOON_HINT_BLOCK_ORDER)
  41
  42enum virtio_balloon_vq {
  43	VIRTIO_BALLOON_VQ_INFLATE,
  44	VIRTIO_BALLOON_VQ_DEFLATE,
  45	VIRTIO_BALLOON_VQ_STATS,
  46	VIRTIO_BALLOON_VQ_FREE_PAGE,
  47	VIRTIO_BALLOON_VQ_REPORTING,
  48	VIRTIO_BALLOON_VQ_MAX
  49};
  50
  51enum virtio_balloon_config_read {
  52	VIRTIO_BALLOON_CONFIG_READ_CMD_ID = 0,
  53};
  54
  55struct virtio_balloon {
  56	struct virtio_device *vdev;
  57	struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq;
  58
  59	/* Balloon's own wq for cpu-intensive work items */
  60	struct workqueue_struct *balloon_wq;
  61	/* The free page reporting work item submitted to the balloon wq */
  62	struct work_struct report_free_page_work;
  63
  64	/* The balloon servicing is delegated to a freezable workqueue. */
  65	struct work_struct update_balloon_stats_work;
  66	struct work_struct update_balloon_size_work;
  67
  68	/* Prevent updating balloon when it is being canceled. */
  69	spinlock_t stop_update_lock;
  70	bool stop_update;
  71	/* Bitmap to indicate if reading the related config fields are needed */
  72	unsigned long config_read_bitmap;
  73
  74	/* The list of allocated free pages, waiting to be given back to mm */
  75	struct list_head free_page_list;
  76	spinlock_t free_page_list_lock;
  77	/* The number of free page blocks on the above list */
  78	unsigned long num_free_page_blocks;
  79	/*
  80	 * The cmd id received from host.
  81	 * Read it via virtio_balloon_cmd_id_received to get the latest value
  82	 * sent from host.
  83	 */
  84	u32 cmd_id_received_cache;
  85	/* The cmd id that is actively in use */
  86	__virtio32 cmd_id_active;
  87	/* Buffer to store the stop sign */
  88	__virtio32 cmd_id_stop;
  89
  90	/* Waiting for host to ack the pages we released. */
  91	wait_queue_head_t acked;
  92
  93	/* Number of balloon pages we've told the Host we're not using. */
  94	unsigned int num_pages;
  95	/*
  96	 * The pages we've told the Host we're not using are enqueued
  97	 * at vb_dev_info->pages list.
  98	 * Each page on this list adds VIRTIO_BALLOON_PAGES_PER_PAGE
  99	 * to num_pages above.
 100	 */
 101	struct balloon_dev_info vb_dev_info;
 102
 103	/* Synchronize access/update to this struct virtio_balloon elements */
 104	struct mutex balloon_lock;
 105
 106	/* The array of pfns we tell the Host about. */
 107	unsigned int num_pfns;
 108	__virtio32 pfns[VIRTIO_BALLOON_ARRAY_PFNS_MAX];
 109
 110	/* Memory statistics */
 111	struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR];
 112
 113	/* Shrinker to return free pages - VIRTIO_BALLOON_F_FREE_PAGE_HINT */
 114	struct shrinker *shrinker;
 115
 116	/* OOM notifier to deflate on OOM - VIRTIO_BALLOON_F_DEFLATE_ON_OOM */
 117	struct notifier_block oom_nb;
 118
 119	/* Free page reporting device */
 120	struct virtqueue *reporting_vq;
 121	struct page_reporting_dev_info pr_dev_info;
 122
 123	/* State for keeping the wakeup_source active while adjusting the balloon */
 124	spinlock_t wakeup_lock;
 125	bool processing_wakeup_event;
 126	u32 wakeup_signal_mask;
 127};
 128
 129#define VIRTIO_BALLOON_WAKEUP_SIGNAL_ADJUST (1 << 0)
 130#define VIRTIO_BALLOON_WAKEUP_SIGNAL_STATS (1 << 1)
 131
 132static const struct virtio_device_id id_table[] = {
 133	{ VIRTIO_ID_BALLOON, VIRTIO_DEV_ANY_ID },
 134	{ 0 },
 135};
 136
 137static u32 page_to_balloon_pfn(struct page *page)
 138{
 139	unsigned long pfn = page_to_pfn(page);
 140
 141	BUILD_BUG_ON(PAGE_SHIFT < VIRTIO_BALLOON_PFN_SHIFT);
 142	/* Convert pfn from Linux page size to balloon page size. */
 143	return pfn * VIRTIO_BALLOON_PAGES_PER_PAGE;
 144}
 145
 146static void start_wakeup_event(struct virtio_balloon *vb, u32 mask)
 147{
 148	unsigned long flags;
 149
 150	spin_lock_irqsave(&vb->wakeup_lock, flags);
 151	vb->wakeup_signal_mask |= mask;
 152	if (!vb->processing_wakeup_event) {
 153		vb->processing_wakeup_event = true;
 154		pm_stay_awake(&vb->vdev->dev);
 155	}
 156	spin_unlock_irqrestore(&vb->wakeup_lock, flags);
 157}
 158
 159static void process_wakeup_event(struct virtio_balloon *vb, u32 mask)
 160{
 161	spin_lock_irq(&vb->wakeup_lock);
 162	vb->wakeup_signal_mask &= ~mask;
 163	spin_unlock_irq(&vb->wakeup_lock);
 164}
 165
 166static void finish_wakeup_event(struct virtio_balloon *vb)
 167{
 168	spin_lock_irq(&vb->wakeup_lock);
 169	if (!vb->wakeup_signal_mask && vb->processing_wakeup_event) {
 170		vb->processing_wakeup_event = false;
 171		pm_relax(&vb->vdev->dev);
 172	}
 173	spin_unlock_irq(&vb->wakeup_lock);
 174}
 175
 176static void balloon_ack(struct virtqueue *vq)
 177{
 178	struct virtio_balloon *vb = vq->vdev->priv;
 179
 180	wake_up(&vb->acked);
 181}
 182
 183static void tell_host(struct virtio_balloon *vb, struct virtqueue *vq)
 184{
 185	struct scatterlist sg;
 186	unsigned int len;
 187
 188	sg_init_one(&sg, vb->pfns, sizeof(vb->pfns[0]) * vb->num_pfns);
 189
 190	/* We should always be able to add one buffer to an empty queue. */
 191	virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL);
 192	virtqueue_kick(vq);
 193
 194	/* When host has read buffer, this completes via balloon_ack */
 195	wait_event(vb->acked, virtqueue_get_buf(vq, &len));
 196
 197}
 198
 199static int virtballoon_free_page_report(struct page_reporting_dev_info *pr_dev_info,
 200				   struct scatterlist *sg, unsigned int nents)
 201{
 202	struct virtio_balloon *vb =
 203		container_of(pr_dev_info, struct virtio_balloon, pr_dev_info);
 204	struct virtqueue *vq = vb->reporting_vq;
 205	unsigned int unused, err;
 206
 207	/* We should always be able to add these buffers to an empty queue. */
 208	err = virtqueue_add_inbuf(vq, sg, nents, vb, GFP_NOWAIT);
 209
 210	/*
 211	 * In the extremely unlikely case that something has occurred and we
 212	 * are able to trigger an error we will simply display a warning
 213	 * and exit without actually processing the pages.
 214	 */
 215	if (WARN_ON_ONCE(err))
 216		return err;
 217
 218	virtqueue_kick(vq);
 219
 220	/* When host has read buffer, this completes via balloon_ack */
 221	wait_event(vb->acked, virtqueue_get_buf(vq, &unused));
 222
 223	return 0;
 224}
 225
 226static void set_page_pfns(struct virtio_balloon *vb,
 227			  __virtio32 pfns[], struct page *page)
 228{
 229	unsigned int i;
 230
 231	BUILD_BUG_ON(VIRTIO_BALLOON_PAGES_PER_PAGE > VIRTIO_BALLOON_ARRAY_PFNS_MAX);
 232
 233	/*
 234	 * Set balloon pfns pointing at this page.
 235	 * Note that the first pfn points at start of the page.
 236	 */
 237	for (i = 0; i < VIRTIO_BALLOON_PAGES_PER_PAGE; i++)
 238		pfns[i] = cpu_to_virtio32(vb->vdev,
 239					  page_to_balloon_pfn(page) + i);
 240}
 241
 242static unsigned int fill_balloon(struct virtio_balloon *vb, size_t num)
 243{
 244	unsigned int num_allocated_pages;
 245	unsigned int num_pfns;
 246	struct page *page;
 247	LIST_HEAD(pages);
 248
 249	/* We can only do one array worth at a time. */
 250	num = min(num, ARRAY_SIZE(vb->pfns));
 251
 252	for (num_pfns = 0; num_pfns < num;
 253	     num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) {
 254		page = balloon_page_alloc();
 255
 256		if (!page) {
 257			dev_info_ratelimited(&vb->vdev->dev,
 258					     "Out of puff! Can't get %u pages\n",
 259					     VIRTIO_BALLOON_PAGES_PER_PAGE);
 260			/* Sleep for at least 1/5 of a second before retry. */
 261			msleep(200);
 262			break;
 263		}
 264
 265		balloon_page_push(&pages, page);
 266	}
 267
 268	mutex_lock(&vb->balloon_lock);
 269
 270	vb->num_pfns = 0;
 271
 272	while ((page = balloon_page_pop(&pages))) {
 273		balloon_page_enqueue(&vb->vb_dev_info, page);
 274
 275		set_page_pfns(vb, vb->pfns + vb->num_pfns, page);
 276		vb->num_pages += VIRTIO_BALLOON_PAGES_PER_PAGE;
 277		if (!virtio_has_feature(vb->vdev,
 278					VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
 279			adjust_managed_page_count(page, -1);
 280		vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE;
 281	}
 282
 283	num_allocated_pages = vb->num_pfns;
 284	/* Did we get any? */
 285	if (vb->num_pfns != 0)
 286		tell_host(vb, vb->inflate_vq);
 287	mutex_unlock(&vb->balloon_lock);
 288
 289	return num_allocated_pages;
 290}
 291
 292static void release_pages_balloon(struct virtio_balloon *vb,
 293				 struct list_head *pages)
 294{
 295	struct page *page, *next;
 296
 297	list_for_each_entry_safe(page, next, pages, lru) {
 298		if (!virtio_has_feature(vb->vdev,
 299					VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
 300			adjust_managed_page_count(page, 1);
 301		list_del(&page->lru);
 302		put_page(page); /* balloon reference */
 303	}
 304}
 305
 306static unsigned int leak_balloon(struct virtio_balloon *vb, size_t num)
 307{
 308	unsigned int num_freed_pages;
 309	struct page *page;
 310	struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info;
 311	LIST_HEAD(pages);
 312
 313	/* We can only do one array worth at a time. */
 314	num = min(num, ARRAY_SIZE(vb->pfns));
 315
 316	mutex_lock(&vb->balloon_lock);
 317	/* We can't release more pages than taken */
 318	num = min(num, (size_t)vb->num_pages);
 319	for (vb->num_pfns = 0; vb->num_pfns < num;
 320	     vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) {
 321		page = balloon_page_dequeue(vb_dev_info);
 322		if (!page)
 323			break;
 324		set_page_pfns(vb, vb->pfns + vb->num_pfns, page);
 325		list_add(&page->lru, &pages);
 326		vb->num_pages -= VIRTIO_BALLOON_PAGES_PER_PAGE;
 327	}
 328
 329	num_freed_pages = vb->num_pfns;
 330	/*
 331	 * Note that if
 332	 * virtio_has_feature(vdev, VIRTIO_BALLOON_F_MUST_TELL_HOST);
 333	 * is true, we *have* to do it in this order
 334	 */
 335	if (vb->num_pfns != 0)
 336		tell_host(vb, vb->deflate_vq);
 337	release_pages_balloon(vb, &pages);
 338	mutex_unlock(&vb->balloon_lock);
 339	return num_freed_pages;
 340}
 341
 342static inline void update_stat(struct virtio_balloon *vb, int idx,
 343			       u16 tag, u64 val)
 344{
 345	BUG_ON(idx >= VIRTIO_BALLOON_S_NR);
 346	vb->stats[idx].tag = cpu_to_virtio16(vb->vdev, tag);
 347	vb->stats[idx].val = cpu_to_virtio64(vb->vdev, val);
 348}
 349
 350#define pages_to_bytes(x) ((u64)(x) << PAGE_SHIFT)
 351
 352#ifdef CONFIG_VM_EVENT_COUNTERS
 353/* Return the number of entries filled by vm events */
 354static inline unsigned int update_balloon_vm_stats(struct virtio_balloon *vb)
 355{
 356	unsigned long events[NR_VM_EVENT_ITEMS];
 357	unsigned int idx = 0;
 358	unsigned int zid;
 359	unsigned long stall = 0;
 360
 361	all_vm_events(events);
 362	update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_IN,
 363		    pages_to_bytes(events[PSWPIN]));
 364	update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_OUT,
 365		    pages_to_bytes(events[PSWPOUT]));
 366	update_stat(vb, idx++, VIRTIO_BALLOON_S_MAJFLT, events[PGMAJFAULT]);
 367	update_stat(vb, idx++, VIRTIO_BALLOON_S_MINFLT, events[PGFAULT]);
 368	update_stat(vb, idx++, VIRTIO_BALLOON_S_OOM_KILL, events[OOM_KILL]);
 369
 370	/* sum all the stall events */
 371	for (zid = 0; zid < MAX_NR_ZONES; zid++)
 372		stall += events[ALLOCSTALL_NORMAL - ZONE_NORMAL + zid];
 373
 374	update_stat(vb, idx++, VIRTIO_BALLOON_S_ALLOC_STALL, stall);
 375
 376	update_stat(vb, idx++, VIRTIO_BALLOON_S_ASYNC_SCAN,
 377		    pages_to_bytes(events[PGSCAN_KSWAPD]));
 378	update_stat(vb, idx++, VIRTIO_BALLOON_S_DIRECT_SCAN,
 379		    pages_to_bytes(events[PGSCAN_DIRECT]));
 380	update_stat(vb, idx++, VIRTIO_BALLOON_S_ASYNC_RECLAIM,
 381		    pages_to_bytes(events[PGSTEAL_KSWAPD]));
 382	update_stat(vb, idx++, VIRTIO_BALLOON_S_DIRECT_RECLAIM,
 383		    pages_to_bytes(events[PGSTEAL_DIRECT]));
 384
 385#ifdef CONFIG_HUGETLB_PAGE
 386	update_stat(vb, idx++, VIRTIO_BALLOON_S_HTLB_PGALLOC,
 387		    events[HTLB_BUDDY_PGALLOC]);
 388	update_stat(vb, idx++, VIRTIO_BALLOON_S_HTLB_PGFAIL,
 389		    events[HTLB_BUDDY_PGALLOC_FAIL]);
 390#endif /* CONFIG_HUGETLB_PAGE */
 391
 392	return idx;
 393}
 394#else /* CONFIG_VM_EVENT_COUNTERS */
 395static inline unsigned int update_balloon_vm_stats(struct virtio_balloon *vb)
 396{
 397	return 0;
 398}
 399#endif /* CONFIG_VM_EVENT_COUNTERS */
 400
 401static unsigned int update_balloon_stats(struct virtio_balloon *vb)
 402{
 403	struct sysinfo i;
 404	unsigned int idx;
 405	long available;
 406	unsigned long caches;
 407
 408	idx = update_balloon_vm_stats(vb);
 409
 410	si_meminfo(&i);
 411	available = si_mem_available();
 412	caches = global_node_page_state(NR_FILE_PAGES);
 413	update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMFREE,
 414				pages_to_bytes(i.freeram));
 415	update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMTOT,
 416				pages_to_bytes(i.totalram));
 417	update_stat(vb, idx++, VIRTIO_BALLOON_S_AVAIL,
 418				pages_to_bytes(available));
 419	update_stat(vb, idx++, VIRTIO_BALLOON_S_CACHES,
 420				pages_to_bytes(caches));
 421
 422	return idx;
 423}
 424
 425/*
 426 * While most virtqueues communicate guest-initiated requests to the hypervisor,
 427 * the stats queue operates in reverse.  The driver initializes the virtqueue
 428 * with a single buffer.  From that point forward, all conversations consist of
 429 * a hypervisor request (a call to this function) which directs us to refill
 430 * the virtqueue with a fresh stats buffer.  Since stats collection can sleep,
 431 * we delegate the job to a freezable workqueue that will do the actual work via
 432 * stats_handle_request().
 433 */
 434static void stats_request(struct virtqueue *vq)
 435{
 436	struct virtio_balloon *vb = vq->vdev->priv;
 437
 438	spin_lock(&vb->stop_update_lock);
 439	if (!vb->stop_update) {
 440		start_wakeup_event(vb, VIRTIO_BALLOON_WAKEUP_SIGNAL_STATS);
 441		queue_work(system_freezable_wq, &vb->update_balloon_stats_work);
 442	}
 443	spin_unlock(&vb->stop_update_lock);
 444}
 445
 446static void stats_handle_request(struct virtio_balloon *vb)
 447{
 448	struct virtqueue *vq;
 449	struct scatterlist sg;
 450	unsigned int len, num_stats;
 451
 452	num_stats = update_balloon_stats(vb);
 453
 454	vq = vb->stats_vq;
 455	if (!virtqueue_get_buf(vq, &len))
 456		return;
 457	sg_init_one(&sg, vb->stats, sizeof(vb->stats[0]) * num_stats);
 458	virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL);
 459	virtqueue_kick(vq);
 460}
 461
 462static inline s64 towards_target(struct virtio_balloon *vb)
 463{
 464	s64 target;
 465	u32 num_pages;
 466
 467	/* Legacy balloon config space is LE, unlike all other devices. */
 468	virtio_cread_le(vb->vdev, struct virtio_balloon_config, num_pages,
 469			&num_pages);
 470
 471	/*
 472	 * Aligned up to guest page size to avoid inflating and deflating
 473	 * balloon endlessly.
 474	 */
 475	target = ALIGN(num_pages, VIRTIO_BALLOON_PAGES_PER_PAGE);
 476	return target - vb->num_pages;
 477}
 478
 479/* Gives back @num_to_return blocks of free pages to mm. */
 480static unsigned long return_free_pages_to_mm(struct virtio_balloon *vb,
 481					     unsigned long num_to_return)
 482{
 483	struct page *page;
 484	unsigned long num_returned;
 485
 486	spin_lock_irq(&vb->free_page_list_lock);
 487	for (num_returned = 0; num_returned < num_to_return; num_returned++) {
 488		page = balloon_page_pop(&vb->free_page_list);
 489		if (!page)
 490			break;
 491		__free_pages(page, VIRTIO_BALLOON_HINT_BLOCK_ORDER);
 492	}
 493	vb->num_free_page_blocks -= num_returned;
 494	spin_unlock_irq(&vb->free_page_list_lock);
 495
 496	return num_returned;
 497}
 498
 499static void virtio_balloon_queue_free_page_work(struct virtio_balloon *vb)
 500{
 501	if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
 502		return;
 503
 504	/* No need to queue the work if the bit was already set. */
 505	if (test_and_set_bit(VIRTIO_BALLOON_CONFIG_READ_CMD_ID,
 506			     &vb->config_read_bitmap))
 507		return;
 508
 509	queue_work(vb->balloon_wq, &vb->report_free_page_work);
 510}
 511
 512static void start_update_balloon_size(struct virtio_balloon *vb)
 513{
 514	start_wakeup_event(vb, VIRTIO_BALLOON_WAKEUP_SIGNAL_ADJUST);
 515	queue_work(system_freezable_wq, &vb->update_balloon_size_work);
 516}
 517
 518static void virtballoon_changed(struct virtio_device *vdev)
 519{
 520	struct virtio_balloon *vb = vdev->priv;
 521	unsigned long flags;
 522
 523	spin_lock_irqsave(&vb->stop_update_lock, flags);
 524	if (!vb->stop_update) {
 525		start_update_balloon_size(vb);
 526		virtio_balloon_queue_free_page_work(vb);
 527	}
 528	spin_unlock_irqrestore(&vb->stop_update_lock, flags);
 529}
 530
 531static void update_balloon_size(struct virtio_balloon *vb)
 532{
 533	u32 actual = vb->num_pages;
 534
 535	/* Legacy balloon config space is LE, unlike all other devices. */
 536	virtio_cwrite_le(vb->vdev, struct virtio_balloon_config, actual,
 537			 &actual);
 538}
 539
 540static void update_balloon_stats_func(struct work_struct *work)
 541{
 542	struct virtio_balloon *vb;
 543
 544	vb = container_of(work, struct virtio_balloon,
 545			  update_balloon_stats_work);
 546
 547	process_wakeup_event(vb, VIRTIO_BALLOON_WAKEUP_SIGNAL_STATS);
 548	stats_handle_request(vb);
 549	finish_wakeup_event(vb);
 550}
 551
 552static void update_balloon_size_func(struct work_struct *work)
 553{
 554	struct virtio_balloon *vb;
 555	s64 diff;
 556
 557	vb = container_of(work, struct virtio_balloon,
 558			  update_balloon_size_work);
 559
 560	process_wakeup_event(vb, VIRTIO_BALLOON_WAKEUP_SIGNAL_ADJUST);
 561
 562	diff = towards_target(vb);
 563
 564	if (diff) {
 565		if (diff > 0)
 566			diff -= fill_balloon(vb, diff);
 567		else
 568			diff += leak_balloon(vb, -diff);
 569		update_balloon_size(vb);
 570	}
 571
 572	if (diff)
 573		queue_work(system_freezable_wq, work);
 574	else
 575		finish_wakeup_event(vb);
 576}
 577
 578static int init_vqs(struct virtio_balloon *vb)
 579{
 580	struct virtqueue_info vqs_info[VIRTIO_BALLOON_VQ_MAX] = {};
 581	struct virtqueue *vqs[VIRTIO_BALLOON_VQ_MAX];
 582	int err;
 583
 584	/*
 585	 * Inflateq and deflateq are used unconditionally. The names[]
 586	 * will be NULL if the related feature is not enabled, which will
 587	 * cause no allocation for the corresponding virtqueue in find_vqs.
 588	 */
 589	vqs_info[VIRTIO_BALLOON_VQ_INFLATE].callback = balloon_ack;
 590	vqs_info[VIRTIO_BALLOON_VQ_INFLATE].name = "inflate";
 591	vqs_info[VIRTIO_BALLOON_VQ_DEFLATE].callback = balloon_ack;
 592	vqs_info[VIRTIO_BALLOON_VQ_DEFLATE].name = "deflate";
 593
 594	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {
 595		vqs_info[VIRTIO_BALLOON_VQ_STATS].name = "stats";
 596		vqs_info[VIRTIO_BALLOON_VQ_STATS].callback = stats_request;
 597	}
 598
 599	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
 600		vqs_info[VIRTIO_BALLOON_VQ_FREE_PAGE].name = "free_page_vq";
 601
 602	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING)) {
 603		vqs_info[VIRTIO_BALLOON_VQ_REPORTING].name = "reporting_vq";
 604		vqs_info[VIRTIO_BALLOON_VQ_REPORTING].callback = balloon_ack;
 605	}
 606
 607	err = virtio_find_vqs(vb->vdev, VIRTIO_BALLOON_VQ_MAX, vqs,
 608			      vqs_info, NULL);
 609	if (err)
 610		return err;
 611
 612	vb->inflate_vq = vqs[VIRTIO_BALLOON_VQ_INFLATE];
 613	vb->deflate_vq = vqs[VIRTIO_BALLOON_VQ_DEFLATE];
 614	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {
 615		struct scatterlist sg;
 616		unsigned int num_stats;
 617		vb->stats_vq = vqs[VIRTIO_BALLOON_VQ_STATS];
 618
 619		/*
 620		 * Prime this virtqueue with one buffer so the hypervisor can
 621		 * use it to signal us later (it can't be broken yet!).
 622		 */
 623		num_stats = update_balloon_stats(vb);
 624
 625		sg_init_one(&sg, vb->stats, sizeof(vb->stats[0]) * num_stats);
 626		err = virtqueue_add_outbuf(vb->stats_vq, &sg, 1, vb,
 627					   GFP_KERNEL);
 628		if (err) {
 629			dev_warn(&vb->vdev->dev, "%s: add stat_vq failed\n",
 630				 __func__);
 631			return err;
 632		}
 633		virtqueue_kick(vb->stats_vq);
 634	}
 635
 636	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
 637		vb->free_page_vq = vqs[VIRTIO_BALLOON_VQ_FREE_PAGE];
 638
 639	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING))
 640		vb->reporting_vq = vqs[VIRTIO_BALLOON_VQ_REPORTING];
 641
 642	return 0;
 643}
 644
 645static u32 virtio_balloon_cmd_id_received(struct virtio_balloon *vb)
 646{
 647	if (test_and_clear_bit(VIRTIO_BALLOON_CONFIG_READ_CMD_ID,
 648			       &vb->config_read_bitmap)) {
 649		/* Legacy balloon config space is LE, unlike all other devices. */
 650		virtio_cread_le(vb->vdev, struct virtio_balloon_config,
 651				free_page_hint_cmd_id,
 652				&vb->cmd_id_received_cache);
 653	}
 654
 655	return vb->cmd_id_received_cache;
 656}
 657
 658static int send_cmd_id_start(struct virtio_balloon *vb)
 659{
 660	struct scatterlist sg;
 661	struct virtqueue *vq = vb->free_page_vq;
 662	int err, unused;
 663
 664	/* Detach all the used buffers from the vq */
 665	while (virtqueue_get_buf(vq, &unused))
 666		;
 667
 668	vb->cmd_id_active = cpu_to_virtio32(vb->vdev,
 669					virtio_balloon_cmd_id_received(vb));
 670	sg_init_one(&sg, &vb->cmd_id_active, sizeof(vb->cmd_id_active));
 671	err = virtqueue_add_outbuf(vq, &sg, 1, &vb->cmd_id_active, GFP_KERNEL);
 672	if (!err)
 673		virtqueue_kick(vq);
 674	return err;
 675}
 676
 677static int send_cmd_id_stop(struct virtio_balloon *vb)
 678{
 679	struct scatterlist sg;
 680	struct virtqueue *vq = vb->free_page_vq;
 681	int err, unused;
 682
 683	/* Detach all the used buffers from the vq */
 684	while (virtqueue_get_buf(vq, &unused))
 685		;
 686
 687	sg_init_one(&sg, &vb->cmd_id_stop, sizeof(vb->cmd_id_stop));
 688	err = virtqueue_add_outbuf(vq, &sg, 1, &vb->cmd_id_stop, GFP_KERNEL);
 689	if (!err)
 690		virtqueue_kick(vq);
 691	return err;
 692}
 693
 694static int get_free_page_and_send(struct virtio_balloon *vb)
 695{
 696	struct virtqueue *vq = vb->free_page_vq;
 697	struct page *page;
 698	struct scatterlist sg;
 699	int err, unused;
 700	void *p;
 701
 702	/* Detach all the used buffers from the vq */
 703	while (virtqueue_get_buf(vq, &unused))
 704		;
 705
 706	page = alloc_pages(VIRTIO_BALLOON_FREE_PAGE_ALLOC_FLAG,
 707			   VIRTIO_BALLOON_HINT_BLOCK_ORDER);
 708	/*
 709	 * When the allocation returns NULL, it indicates that we have got all
 710	 * the possible free pages, so return -EINTR to stop.
 711	 */
 712	if (!page)
 713		return -EINTR;
 714
 715	p = page_address(page);
 716	sg_init_one(&sg, p, VIRTIO_BALLOON_HINT_BLOCK_BYTES);
 717	/* There is always 1 entry reserved for the cmd id to use. */
 718	if (vq->num_free > 1) {
 719		err = virtqueue_add_inbuf(vq, &sg, 1, p, GFP_KERNEL);
 720		if (unlikely(err)) {
 721			__free_pages(page, VIRTIO_BALLOON_HINT_BLOCK_ORDER);
 722			return err;
 723		}
 724		virtqueue_kick(vq);
 725		spin_lock_irq(&vb->free_page_list_lock);
 726		balloon_page_push(&vb->free_page_list, page);
 727		vb->num_free_page_blocks++;
 728		spin_unlock_irq(&vb->free_page_list_lock);
 729	} else {
 730		/*
 731		 * The vq has no available entry to add this page block, so
 732		 * just free it.
 733		 */
 734		__free_pages(page, VIRTIO_BALLOON_HINT_BLOCK_ORDER);
 735	}
 736
 737	return 0;
 738}
 739
 740static int send_free_pages(struct virtio_balloon *vb)
 741{
 742	int err;
 743	u32 cmd_id_active;
 744
 745	while (1) {
 746		/*
 747		 * If a stop id or a new cmd id was just received from host,
 748		 * stop the reporting.
 749		 */
 750		cmd_id_active = virtio32_to_cpu(vb->vdev, vb->cmd_id_active);
 751		if (unlikely(cmd_id_active !=
 752			     virtio_balloon_cmd_id_received(vb)))
 753			break;
 754
 755		/*
 756		 * The free page blocks are allocated and sent to host one by
 757		 * one.
 758		 */
 759		err = get_free_page_and_send(vb);
 760		if (err == -EINTR)
 761			break;
 762		else if (unlikely(err))
 763			return err;
 764	}
 765
 766	return 0;
 767}
 768
 769static void virtio_balloon_report_free_page(struct virtio_balloon *vb)
 770{
 771	int err;
 772	struct device *dev = &vb->vdev->dev;
 773
 774	/* Start by sending the received cmd id to host with an outbuf. */
 775	err = send_cmd_id_start(vb);
 776	if (unlikely(err))
 777		dev_err(dev, "Failed to send a start id, err = %d\n", err);
 778
 779	err = send_free_pages(vb);
 780	if (unlikely(err))
 781		dev_err(dev, "Failed to send a free page, err = %d\n", err);
 782
 783	/* End by sending a stop id to host with an outbuf. */
 784	err = send_cmd_id_stop(vb);
 785	if (unlikely(err))
 786		dev_err(dev, "Failed to send a stop id, err = %d\n", err);
 787}
 788
 789static void report_free_page_func(struct work_struct *work)
 790{
 791	struct virtio_balloon *vb = container_of(work, struct virtio_balloon,
 792						 report_free_page_work);
 793	u32 cmd_id_received;
 794
 795	cmd_id_received = virtio_balloon_cmd_id_received(vb);
 796	if (cmd_id_received == VIRTIO_BALLOON_CMD_ID_DONE) {
 797		/* Pass ULONG_MAX to give back all the free pages */
 798		return_free_pages_to_mm(vb, ULONG_MAX);
 799	} else if (cmd_id_received != VIRTIO_BALLOON_CMD_ID_STOP &&
 800		   cmd_id_received !=
 801		   virtio32_to_cpu(vb->vdev, vb->cmd_id_active)) {
 802		virtio_balloon_report_free_page(vb);
 803	}
 804}
 805
 806#ifdef CONFIG_BALLOON_COMPACTION
 807/*
 808 * virtballoon_migratepage - perform the balloon page migration on behalf of
 809 *			     a compaction thread.     (called under page lock)
 810 * @vb_dev_info: the balloon device
 811 * @newpage: page that will replace the isolated page after migration finishes.
 812 * @page   : the isolated (old) page that is about to be migrated to newpage.
 813 * @mode   : compaction mode -- not used for balloon page migration.
 814 *
 815 * After a ballooned page gets isolated by compaction procedures, this is the
 816 * function that performs the page migration on behalf of a compaction thread
 817 * The page migration for virtio balloon is done in a simple swap fashion which
 818 * follows these two macro steps:
 819 *  1) insert newpage into vb->pages list and update the host about it;
 820 *  2) update the host about the old page removed from vb->pages list;
 821 *
 822 * This function preforms the balloon page migration task.
 823 * Called through movable_operations->migrate_page
 824 */
 825static int virtballoon_migratepage(struct balloon_dev_info *vb_dev_info,
 826		struct page *newpage, struct page *page, enum migrate_mode mode)
 827{
 828	struct virtio_balloon *vb = container_of(vb_dev_info,
 829			struct virtio_balloon, vb_dev_info);
 830	unsigned long flags;
 831
 832	/*
 833	 * In order to avoid lock contention while migrating pages concurrently
 834	 * to leak_balloon() or fill_balloon() we just give up the balloon_lock
 835	 * this turn, as it is easier to retry the page migration later.
 836	 * This also prevents fill_balloon() getting stuck into a mutex
 837	 * recursion in the case it ends up triggering memory compaction
 838	 * while it is attempting to inflate the ballon.
 839	 */
 840	if (!mutex_trylock(&vb->balloon_lock))
 841		return -EAGAIN;
 842
 843	get_page(newpage); /* balloon reference */
 844
 845	/*
 846	  * When we migrate a page to a different zone and adjusted the
 847	  * managed page count when inflating, we have to fixup the count of
 848	  * both involved zones.
 849	  */
 850	if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM) &&
 851	    page_zone(page) != page_zone(newpage)) {
 852		adjust_managed_page_count(page, 1);
 853		adjust_managed_page_count(newpage, -1);
 854	}
 855
 856	/* balloon's page migration 1st step  -- inflate "newpage" */
 857	spin_lock_irqsave(&vb_dev_info->pages_lock, flags);
 858	balloon_page_insert(vb_dev_info, newpage);
 859	vb_dev_info->isolated_pages--;
 860	__count_vm_event(BALLOON_MIGRATE);
 861	spin_unlock_irqrestore(&vb_dev_info->pages_lock, flags);
 862	vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE;
 863	set_page_pfns(vb, vb->pfns, newpage);
 864	tell_host(vb, vb->inflate_vq);
 865
 866	/* balloon's page migration 2nd step -- deflate "page" */
 867	vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE;
 868	set_page_pfns(vb, vb->pfns, page);
 869	tell_host(vb, vb->deflate_vq);
 870
 871	mutex_unlock(&vb->balloon_lock);
 872
 873	balloon_page_finalize(page);
 874	put_page(page); /* balloon reference */
 875
 876	return 0;
 877}
 878#endif /* CONFIG_BALLOON_COMPACTION */
 879
 880static unsigned long shrink_free_pages(struct virtio_balloon *vb,
 881				       unsigned long pages_to_free)
 882{
 883	unsigned long blocks_to_free, blocks_freed;
 884
 885	pages_to_free = round_up(pages_to_free,
 886				 VIRTIO_BALLOON_HINT_BLOCK_PAGES);
 887	blocks_to_free = pages_to_free / VIRTIO_BALLOON_HINT_BLOCK_PAGES;
 888	blocks_freed = return_free_pages_to_mm(vb, blocks_to_free);
 889
 890	return blocks_freed * VIRTIO_BALLOON_HINT_BLOCK_PAGES;
 891}
 892
 893static unsigned long virtio_balloon_shrinker_scan(struct shrinker *shrinker,
 894						  struct shrink_control *sc)
 895{
 896	struct virtio_balloon *vb = shrinker->private_data;
 897
 898	return shrink_free_pages(vb, sc->nr_to_scan);
 899}
 900
 901static unsigned long virtio_balloon_shrinker_count(struct shrinker *shrinker,
 902						   struct shrink_control *sc)
 903{
 904	struct virtio_balloon *vb = shrinker->private_data;
 905
 906	return vb->num_free_page_blocks * VIRTIO_BALLOON_HINT_BLOCK_PAGES;
 907}
 908
 909static int virtio_balloon_oom_notify(struct notifier_block *nb,
 910				     unsigned long dummy, void *parm)
 911{
 912	struct virtio_balloon *vb = container_of(nb,
 913						 struct virtio_balloon, oom_nb);
 914	unsigned long *freed = parm;
 915
 916	*freed += leak_balloon(vb, VIRTIO_BALLOON_OOM_NR_PAGES) /
 917		  VIRTIO_BALLOON_PAGES_PER_PAGE;
 918	update_balloon_size(vb);
 919
 920	return NOTIFY_OK;
 921}
 922
 923static void virtio_balloon_unregister_shrinker(struct virtio_balloon *vb)
 924{
 925	shrinker_free(vb->shrinker);
 926}
 927
 928static int virtio_balloon_register_shrinker(struct virtio_balloon *vb)
 929{
 930	vb->shrinker = shrinker_alloc(0, "virtio-balloon");
 931	if (!vb->shrinker)
 932		return -ENOMEM;
 933
 934	vb->shrinker->scan_objects = virtio_balloon_shrinker_scan;
 935	vb->shrinker->count_objects = virtio_balloon_shrinker_count;
 936	vb->shrinker->private_data = vb;
 937
 938	shrinker_register(vb->shrinker);
 939
 940	return 0;
 941}
 942
 943static int virtballoon_probe(struct virtio_device *vdev)
 944{
 945	struct virtio_balloon *vb;
 946	int err;
 947
 948	if (!vdev->config->get) {
 949		dev_err(&vdev->dev, "%s failure: config access disabled\n",
 950			__func__);
 951		return -EINVAL;
 952	}
 953
 954	vdev->priv = vb = kzalloc(sizeof(*vb), GFP_KERNEL);
 955	if (!vb) {
 956		err = -ENOMEM;
 957		goto out;
 958	}
 959
 960	INIT_WORK(&vb->update_balloon_stats_work, update_balloon_stats_func);
 961	INIT_WORK(&vb->update_balloon_size_work, update_balloon_size_func);
 962	spin_lock_init(&vb->stop_update_lock);
 963	mutex_init(&vb->balloon_lock);
 964	init_waitqueue_head(&vb->acked);
 965	vb->vdev = vdev;
 966
 967	balloon_devinfo_init(&vb->vb_dev_info);
 968
 969	err = init_vqs(vb);
 970	if (err)
 971		goto out_free_vb;
 972
 973#ifdef CONFIG_BALLOON_COMPACTION
 974	vb->vb_dev_info.migratepage = virtballoon_migratepage;
 975#endif
 976	if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {
 977		/*
 978		 * There is always one entry reserved for cmd id, so the ring
 979		 * size needs to be at least two to report free page hints.
 980		 */
 981		if (virtqueue_get_vring_size(vb->free_page_vq) < 2) {
 982			err = -ENOSPC;
 983			goto out_del_vqs;
 984		}
 985		vb->balloon_wq = alloc_workqueue("balloon-wq",
 986					WQ_FREEZABLE | WQ_CPU_INTENSIVE | WQ_PERCPU,
 987					0);
 988		if (!vb->balloon_wq) {
 989			err = -ENOMEM;
 990			goto out_del_vqs;
 991		}
 992		INIT_WORK(&vb->report_free_page_work, report_free_page_func);
 993		vb->cmd_id_received_cache = VIRTIO_BALLOON_CMD_ID_STOP;
 994		vb->cmd_id_active = cpu_to_virtio32(vb->vdev,
 995						  VIRTIO_BALLOON_CMD_ID_STOP);
 996		vb->cmd_id_stop = cpu_to_virtio32(vb->vdev,
 997						  VIRTIO_BALLOON_CMD_ID_STOP);
 998		spin_lock_init(&vb->free_page_list_lock);
 999		INIT_LIST_HEAD(&vb->free_page_list);
1000		/*
1001		 * We're allowed to reuse any free pages, even if they are
1002		 * still to be processed by the host.
1003		 */
1004		err = virtio_balloon_register_shrinker(vb);
1005		if (err)
1006			goto out_del_balloon_wq;
1007	}
1008
1009	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) {
1010		vb->oom_nb.notifier_call = virtio_balloon_oom_notify;
1011		vb->oom_nb.priority = VIRTIO_BALLOON_OOM_NOTIFY_PRIORITY;
1012		err = register_oom_notifier(&vb->oom_nb);
1013		if (err < 0)
1014			goto out_unregister_shrinker;
1015	}
1016
1017	if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON)) {
1018		/* Start with poison val of 0 representing general init */
1019		__u32 poison_val = 0;
1020
1021		/*
1022		 * Let the hypervisor know that we are expecting a
1023		 * specific value to be written back in balloon pages.
1024		 *
1025		 * If the PAGE_POISON value was larger than a byte we would
1026		 * need to byte swap poison_val here to guarantee it is
1027		 * little-endian. However for now it is a single byte so we
1028		 * can pass it as-is.
1029		 */
1030		if (!want_init_on_free())
1031			memset(&poison_val, PAGE_POISON, sizeof(poison_val));
1032
1033		virtio_cwrite_le(vb->vdev, struct virtio_balloon_config,
1034				 poison_val, &poison_val);
1035	}
1036
1037	vb->pr_dev_info.report = virtballoon_free_page_report;
1038	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING)) {
1039		unsigned int capacity;
1040
1041		capacity = virtqueue_get_vring_size(vb->reporting_vq);
1042		if (capacity < PAGE_REPORTING_CAPACITY) {
1043			err = -ENOSPC;
1044			goto out_unregister_oom;
1045		}
1046
1047		/*
1048		 * The default page reporting order is @pageblock_order, which
1049		 * corresponds to 512MB in size on ARM64 when 64KB base page
1050		 * size is used. The page reporting won't be triggered if the
1051		 * freeing page can't come up with a free area like that huge.
1052		 * So we specify the page reporting order to 5, corresponding
1053		 * to 2MB. It helps to avoid THP splitting if 4KB base page
1054		 * size is used by host.
1055		 *
1056		 * Ideally, the page reporting order is selected based on the
1057		 * host's base page size. However, it needs more work to report
1058		 * that value. The hard-coded order would be fine currently.
1059		 */
1060#if defined(CONFIG_ARM64) && defined(CONFIG_ARM64_64K_PAGES)
1061		vb->pr_dev_info.order = 5;
1062#endif
1063
1064		err = page_reporting_register(&vb->pr_dev_info);
1065		if (err)
1066			goto out_unregister_oom;
1067	}
1068
1069	spin_lock_init(&vb->wakeup_lock);
1070
1071	/*
1072	 * The virtio balloon itself can't wake up the device, but it is
1073	 * responsible for processing wakeup events passed up from the transport
1074	 * layer. Wakeup sources don't support nesting/chaining calls, so we use
1075	 * our own wakeup source to ensure wakeup events are properly handled
1076	 * without trampling on the transport layer's wakeup source.
1077	 */
1078	device_set_wakeup_capable(&vb->vdev->dev, true);
1079
1080	virtio_device_ready(vdev);
1081
1082	if (towards_target(vb))
1083		virtballoon_changed(vdev);
1084	return 0;
1085
1086out_unregister_oom:
1087	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
1088		unregister_oom_notifier(&vb->oom_nb);
1089out_unregister_shrinker:
1090	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
1091		virtio_balloon_unregister_shrinker(vb);
1092out_del_balloon_wq:
1093	if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
1094		destroy_workqueue(vb->balloon_wq);
1095out_del_vqs:
1096	vdev->config->del_vqs(vdev);
1097out_free_vb:
1098	kfree(vb);
1099out:
1100	return err;
1101}
1102
1103static void remove_common(struct virtio_balloon *vb)
1104{
1105	/* There might be pages left in the balloon: free them. */
1106	while (vb->num_pages)
1107		leak_balloon(vb, vb->num_pages);
1108	update_balloon_size(vb);
1109
1110	/* There might be free pages that are being reported: release them. */
1111	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
1112		return_free_pages_to_mm(vb, ULONG_MAX);
1113
1114	/* Now we reset the device so we can clean up the queues. */
1115	virtio_reset_device(vb->vdev);
1116
1117	vb->vdev->config->del_vqs(vb->vdev);
1118}
1119
1120static void virtballoon_remove(struct virtio_device *vdev)
1121{
1122	struct virtio_balloon *vb = vdev->priv;
1123
1124	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING))
1125		page_reporting_unregister(&vb->pr_dev_info);
1126	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
1127		unregister_oom_notifier(&vb->oom_nb);
1128	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
1129		virtio_balloon_unregister_shrinker(vb);
1130	spin_lock_irq(&vb->stop_update_lock);
1131	vb->stop_update = true;
1132	spin_unlock_irq(&vb->stop_update_lock);
1133	cancel_work_sync(&vb->update_balloon_size_work);
1134	cancel_work_sync(&vb->update_balloon_stats_work);
1135
1136	if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {
1137		cancel_work_sync(&vb->report_free_page_work);
1138		destroy_workqueue(vb->balloon_wq);
1139	}
1140
1141	remove_common(vb);
1142	kfree(vb);
1143}
1144
1145#ifdef CONFIG_PM_SLEEP
1146static int virtballoon_freeze(struct virtio_device *vdev)
1147{
1148	struct virtio_balloon *vb = vdev->priv;
1149
1150	/*
1151	 * The workqueue is already frozen by the PM core before this
1152	 * function is called.
1153	 */
1154	remove_common(vb);
1155	return 0;
1156}
1157
1158static int virtballoon_restore(struct virtio_device *vdev)
1159{
1160	struct virtio_balloon *vb = vdev->priv;
1161	int ret;
1162
1163	ret = init_vqs(vdev->priv);
1164	if (ret)
1165		return ret;
1166
1167	virtio_device_ready(vdev);
1168
1169	if (towards_target(vb))
1170		virtballoon_changed(vdev);
1171	update_balloon_size(vb);
1172	return 0;
1173}
1174#endif
1175
1176static int virtballoon_validate(struct virtio_device *vdev)
1177{
1178	/*
1179	 * Inform the hypervisor that our pages are poisoned or
1180	 * initialized. If we cannot do that then we should disable
1181	 * page reporting as it could potentially change the contents
1182	 * of our free pages.
1183	 */
1184	if (!want_init_on_free() && !page_poisoning_enabled_static())
1185		__virtio_clear_bit(vdev, VIRTIO_BALLOON_F_PAGE_POISON);
1186	else if (!virtio_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON))
1187		__virtio_clear_bit(vdev, VIRTIO_BALLOON_F_REPORTING);
1188
1189	__virtio_clear_bit(vdev, VIRTIO_F_ACCESS_PLATFORM);
1190	return 0;
1191}
1192
1193static unsigned int features[] = {
1194	VIRTIO_BALLOON_F_MUST_TELL_HOST,
1195	VIRTIO_BALLOON_F_STATS_VQ,
1196	VIRTIO_BALLOON_F_DEFLATE_ON_OOM,
1197	VIRTIO_BALLOON_F_FREE_PAGE_HINT,
1198	VIRTIO_BALLOON_F_PAGE_POISON,
1199	VIRTIO_BALLOON_F_REPORTING,
1200};
1201
1202static struct virtio_driver virtio_balloon_driver = {
1203	.feature_table = features,
1204	.feature_table_size = ARRAY_SIZE(features),
1205	.driver.name =	KBUILD_MODNAME,
1206	.id_table =	id_table,
1207	.validate =	virtballoon_validate,
1208	.probe =	virtballoon_probe,
1209	.remove =	virtballoon_remove,
1210	.config_changed = virtballoon_changed,
1211#ifdef CONFIG_PM_SLEEP
1212	.freeze	=	virtballoon_freeze,
1213	.restore =	virtballoon_restore,
1214#endif
1215};
1216
1217module_virtio_driver(virtio_balloon_driver);
1218MODULE_DEVICE_TABLE(virtio, id_table);
1219MODULE_DESCRIPTION("Virtio balloon driver");
1220MODULE_LICENSE("GPL");