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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * Virtio balloon implementation, inspired by Dor Laor and Marcelo4 * Tosatti's implementations.5 *6 * Copyright 2008 Rusty Russell IBM Corporation7 */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 by24 * multiple balloon pages. All memory counters in this driver are in balloon25 * 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 25629/* Maximum number of (4k) pages to deflate on OOM notifications. */30#define VIRTIO_BALLOON_OOM_NR_PAGES 25631#define VIRTIO_BALLOON_OOM_NOTIFY_PRIORITY 8032 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_ORDER37/* 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_MAX49};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 value82 * 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 enqueued97 * at vb_dev_info->pages list.98 * Each page on this list adds VIRTIO_BALLOON_PAGES_PER_PAGE99 * 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 | __GFP_NOWARN);209 210 /*211 * In the extremely unlikely case that something has occurred and we212 * are able to trigger an error we will simply display a warning213 * 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 struct page *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 if332 * virtio_has_feature(vdev, VIRTIO_BALLOON_F_MUST_TELL_HOST);333 * is true, we *have* to do it in this order334 */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_COUNTERS353/* 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_PAGE386 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 virtqueue428 * with a single buffer. From that point forward, all conversations consist of429 * a hypervisor request (a call to this function) which directs us to refill430 * 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 via432 * 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 deflating473 * 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((unsigned long)page_address(page),492 VIRTIO_BALLOON_HINT_BLOCK_ORDER);493 }494 vb->num_free_page_blocks -= num_returned;495 spin_unlock_irq(&vb->free_page_list_lock);496 497 return num_returned;498}499 500static void virtio_balloon_queue_free_page_work(struct virtio_balloon *vb)501{502 if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))503 return;504 505 /* No need to queue the work if the bit was already set. */506 if (test_and_set_bit(VIRTIO_BALLOON_CONFIG_READ_CMD_ID,507 &vb->config_read_bitmap))508 return;509 510 queue_work(vb->balloon_wq, &vb->report_free_page_work);511}512 513static void start_update_balloon_size(struct virtio_balloon *vb)514{515 start_wakeup_event(vb, VIRTIO_BALLOON_WAKEUP_SIGNAL_ADJUST);516 queue_work(system_freezable_wq, &vb->update_balloon_size_work);517}518 519static void virtballoon_changed(struct virtio_device *vdev)520{521 struct virtio_balloon *vb = vdev->priv;522 unsigned long flags;523 524 spin_lock_irqsave(&vb->stop_update_lock, flags);525 if (!vb->stop_update) {526 start_update_balloon_size(vb);527 virtio_balloon_queue_free_page_work(vb);528 }529 spin_unlock_irqrestore(&vb->stop_update_lock, flags);530}531 532static void update_balloon_size(struct virtio_balloon *vb)533{534 u32 actual = vb->num_pages;535 536 /* Legacy balloon config space is LE, unlike all other devices. */537 virtio_cwrite_le(vb->vdev, struct virtio_balloon_config, actual,538 &actual);539}540 541static void update_balloon_stats_func(struct work_struct *work)542{543 struct virtio_balloon *vb;544 545 vb = container_of(work, struct virtio_balloon,546 update_balloon_stats_work);547 548 process_wakeup_event(vb, VIRTIO_BALLOON_WAKEUP_SIGNAL_STATS);549 stats_handle_request(vb);550 finish_wakeup_event(vb);551}552 553static void update_balloon_size_func(struct work_struct *work)554{555 struct virtio_balloon *vb;556 s64 diff;557 558 vb = container_of(work, struct virtio_balloon,559 update_balloon_size_work);560 561 process_wakeup_event(vb, VIRTIO_BALLOON_WAKEUP_SIGNAL_ADJUST);562 563 diff = towards_target(vb);564 565 if (diff) {566 if (diff > 0)567 diff -= fill_balloon(vb, diff);568 else569 diff += leak_balloon(vb, -diff);570 update_balloon_size(vb);571 }572 573 if (diff)574 queue_work(system_freezable_wq, work);575 else576 finish_wakeup_event(vb);577}578 579static int init_vqs(struct virtio_balloon *vb)580{581 struct virtqueue_info vqs_info[VIRTIO_BALLOON_VQ_MAX] = {};582 struct virtqueue *vqs[VIRTIO_BALLOON_VQ_MAX];583 int err;584 585 /*586 * Inflateq and deflateq are used unconditionally. The names[]587 * will be NULL if the related feature is not enabled, which will588 * cause no allocation for the corresponding virtqueue in find_vqs.589 */590 vqs_info[VIRTIO_BALLOON_VQ_INFLATE].callback = balloon_ack;591 vqs_info[VIRTIO_BALLOON_VQ_INFLATE].name = "inflate";592 vqs_info[VIRTIO_BALLOON_VQ_DEFLATE].callback = balloon_ack;593 vqs_info[VIRTIO_BALLOON_VQ_DEFLATE].name = "deflate";594 595 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {596 vqs_info[VIRTIO_BALLOON_VQ_STATS].name = "stats";597 vqs_info[VIRTIO_BALLOON_VQ_STATS].callback = stats_request;598 }599 600 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))601 vqs_info[VIRTIO_BALLOON_VQ_FREE_PAGE].name = "free_page_vq";602 603 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING)) {604 vqs_info[VIRTIO_BALLOON_VQ_REPORTING].name = "reporting_vq";605 vqs_info[VIRTIO_BALLOON_VQ_REPORTING].callback = balloon_ack;606 }607 608 err = virtio_find_vqs(vb->vdev, VIRTIO_BALLOON_VQ_MAX, vqs,609 vqs_info, NULL);610 if (err)611 return err;612 613 vb->inflate_vq = vqs[VIRTIO_BALLOON_VQ_INFLATE];614 vb->deflate_vq = vqs[VIRTIO_BALLOON_VQ_DEFLATE];615 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {616 struct scatterlist sg;617 unsigned int num_stats;618 vb->stats_vq = vqs[VIRTIO_BALLOON_VQ_STATS];619 620 /*621 * Prime this virtqueue with one buffer so the hypervisor can622 * use it to signal us later (it can't be broken yet!).623 */624 num_stats = update_balloon_stats(vb);625 626 sg_init_one(&sg, vb->stats, sizeof(vb->stats[0]) * num_stats);627 err = virtqueue_add_outbuf(vb->stats_vq, &sg, 1, vb,628 GFP_KERNEL);629 if (err) {630 dev_warn(&vb->vdev->dev, "%s: add stat_vq failed\n",631 __func__);632 return err;633 }634 virtqueue_kick(vb->stats_vq);635 }636 637 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))638 vb->free_page_vq = vqs[VIRTIO_BALLOON_VQ_FREE_PAGE];639 640 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING))641 vb->reporting_vq = vqs[VIRTIO_BALLOON_VQ_REPORTING];642 643 return 0;644}645 646static u32 virtio_balloon_cmd_id_received(struct virtio_balloon *vb)647{648 if (test_and_clear_bit(VIRTIO_BALLOON_CONFIG_READ_CMD_ID,649 &vb->config_read_bitmap)) {650 /* Legacy balloon config space is LE, unlike all other devices. */651 virtio_cread_le(vb->vdev, struct virtio_balloon_config,652 free_page_hint_cmd_id,653 &vb->cmd_id_received_cache);654 }655 656 return vb->cmd_id_received_cache;657}658 659static int send_cmd_id_start(struct virtio_balloon *vb)660{661 struct scatterlist sg;662 struct virtqueue *vq = vb->free_page_vq;663 int err, unused;664 665 /* Detach all the used buffers from the vq */666 while (virtqueue_get_buf(vq, &unused))667 ;668 669 vb->cmd_id_active = cpu_to_virtio32(vb->vdev,670 virtio_balloon_cmd_id_received(vb));671 sg_init_one(&sg, &vb->cmd_id_active, sizeof(vb->cmd_id_active));672 err = virtqueue_add_outbuf(vq, &sg, 1, &vb->cmd_id_active, GFP_KERNEL);673 if (!err)674 virtqueue_kick(vq);675 return err;676}677 678static int send_cmd_id_stop(struct virtio_balloon *vb)679{680 struct scatterlist sg;681 struct virtqueue *vq = vb->free_page_vq;682 int err, unused;683 684 /* Detach all the used buffers from the vq */685 while (virtqueue_get_buf(vq, &unused))686 ;687 688 sg_init_one(&sg, &vb->cmd_id_stop, sizeof(vb->cmd_id_stop));689 err = virtqueue_add_outbuf(vq, &sg, 1, &vb->cmd_id_stop, GFP_KERNEL);690 if (!err)691 virtqueue_kick(vq);692 return err;693}694 695static int get_free_page_and_send(struct virtio_balloon *vb)696{697 struct virtqueue *vq = vb->free_page_vq;698 struct page *page;699 struct scatterlist sg;700 int err, unused;701 void *p;702 703 /* Detach all the used buffers from the vq */704 while (virtqueue_get_buf(vq, &unused))705 ;706 707 page = alloc_pages(VIRTIO_BALLOON_FREE_PAGE_ALLOC_FLAG,708 VIRTIO_BALLOON_HINT_BLOCK_ORDER);709 /*710 * When the allocation returns NULL, it indicates that we have got all711 * the possible free pages, so return -EINTR to stop.712 */713 if (!page)714 return -EINTR;715 716 p = page_address(page);717 sg_init_one(&sg, p, VIRTIO_BALLOON_HINT_BLOCK_BYTES);718 /* There is always 1 entry reserved for the cmd id to use. */719 if (vq->num_free > 1) {720 err = virtqueue_add_inbuf(vq, &sg, 1, p, GFP_KERNEL);721 if (unlikely(err)) {722 free_pages((unsigned long)p,723 VIRTIO_BALLOON_HINT_BLOCK_ORDER);724 return err;725 }726 virtqueue_kick(vq);727 spin_lock_irq(&vb->free_page_list_lock);728 balloon_page_push(&vb->free_page_list, page);729 vb->num_free_page_blocks++;730 spin_unlock_irq(&vb->free_page_list_lock);731 } else {732 /*733 * The vq has no available entry to add this page block, so734 * just free it.735 */736 free_pages((unsigned long)p, VIRTIO_BALLOON_HINT_BLOCK_ORDER);737 }738 739 return 0;740}741 742static int send_free_pages(struct virtio_balloon *vb)743{744 int err;745 u32 cmd_id_active;746 747 while (1) {748 /*749 * If a stop id or a new cmd id was just received from host,750 * stop the reporting.751 */752 cmd_id_active = virtio32_to_cpu(vb->vdev, vb->cmd_id_active);753 if (unlikely(cmd_id_active !=754 virtio_balloon_cmd_id_received(vb)))755 break;756 757 /*758 * The free page blocks are allocated and sent to host one by759 * one.760 */761 err = get_free_page_and_send(vb);762 if (err == -EINTR)763 break;764 else if (unlikely(err))765 return err;766 }767 768 return 0;769}770 771static void virtio_balloon_report_free_page(struct virtio_balloon *vb)772{773 int err;774 struct device *dev = &vb->vdev->dev;775 776 /* Start by sending the received cmd id to host with an outbuf. */777 err = send_cmd_id_start(vb);778 if (unlikely(err))779 dev_err(dev, "Failed to send a start id, err = %d\n", err);780 781 err = send_free_pages(vb);782 if (unlikely(err))783 dev_err(dev, "Failed to send a free page, err = %d\n", err);784 785 /* End by sending a stop id to host with an outbuf. */786 err = send_cmd_id_stop(vb);787 if (unlikely(err))788 dev_err(dev, "Failed to send a stop id, err = %d\n", err);789}790 791static void report_free_page_func(struct work_struct *work)792{793 struct virtio_balloon *vb = container_of(work, struct virtio_balloon,794 report_free_page_work);795 u32 cmd_id_received;796 797 cmd_id_received = virtio_balloon_cmd_id_received(vb);798 if (cmd_id_received == VIRTIO_BALLOON_CMD_ID_DONE) {799 /* Pass ULONG_MAX to give back all the free pages */800 return_free_pages_to_mm(vb, ULONG_MAX);801 } else if (cmd_id_received != VIRTIO_BALLOON_CMD_ID_STOP &&802 cmd_id_received !=803 virtio32_to_cpu(vb->vdev, vb->cmd_id_active)) {804 virtio_balloon_report_free_page(vb);805 }806}807 808#ifdef CONFIG_BALLOON_COMPACTION809/*810 * virtballoon_migratepage - perform the balloon page migration on behalf of811 * a compaction thread. (called under page lock)812 * @vb_dev_info: the balloon device813 * @newpage: page that will replace the isolated page after migration finishes.814 * @page : the isolated (old) page that is about to be migrated to newpage.815 * @mode : compaction mode -- not used for balloon page migration.816 *817 * After a ballooned page gets isolated by compaction procedures, this is the818 * function that performs the page migration on behalf of a compaction thread819 * The page migration for virtio balloon is done in a simple swap fashion which820 * follows these two macro steps:821 * 1) insert newpage into vb->pages list and update the host about it;822 * 2) update the host about the old page removed from vb->pages list;823 *824 * This function preforms the balloon page migration task.825 * Called through movable_operations->migrate_page826 */827static int virtballoon_migratepage(struct balloon_dev_info *vb_dev_info,828 struct page *newpage, struct page *page, enum migrate_mode mode)829{830 struct virtio_balloon *vb = container_of(vb_dev_info,831 struct virtio_balloon, vb_dev_info);832 unsigned long flags;833 834 /*835 * In order to avoid lock contention while migrating pages concurrently836 * to leak_balloon() or fill_balloon() we just give up the balloon_lock837 * this turn, as it is easier to retry the page migration later.838 * This also prevents fill_balloon() getting stuck into a mutex839 * recursion in the case it ends up triggering memory compaction840 * while it is attempting to inflate the ballon.841 */842 if (!mutex_trylock(&vb->balloon_lock))843 return -EAGAIN;844 845 get_page(newpage); /* balloon reference */846 847 /*848 * When we migrate a page to a different zone and adjusted the849 * managed page count when inflating, we have to fixup the count of850 * both involved zones.851 */852 if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM) &&853 page_zone(page) != page_zone(newpage)) {854 adjust_managed_page_count(page, 1);855 adjust_managed_page_count(newpage, -1);856 }857 858 /* balloon's page migration 1st step -- inflate "newpage" */859 spin_lock_irqsave(&vb_dev_info->pages_lock, flags);860 balloon_page_insert(vb_dev_info, newpage);861 vb_dev_info->isolated_pages--;862 __count_vm_event(BALLOON_MIGRATE);863 spin_unlock_irqrestore(&vb_dev_info->pages_lock, flags);864 vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE;865 set_page_pfns(vb, vb->pfns, newpage);866 tell_host(vb, vb->inflate_vq);867 868 /* balloon's page migration 2nd step -- deflate "page" */869 spin_lock_irqsave(&vb_dev_info->pages_lock, flags);870 balloon_page_delete(page);871 spin_unlock_irqrestore(&vb_dev_info->pages_lock, flags);872 vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE;873 set_page_pfns(vb, vb->pfns, page);874 tell_host(vb, vb->deflate_vq);875 876 mutex_unlock(&vb->balloon_lock);877 878 put_page(page); /* balloon reference */879 880 return MIGRATEPAGE_SUCCESS;881}882#endif /* CONFIG_BALLOON_COMPACTION */883 884static unsigned long shrink_free_pages(struct virtio_balloon *vb,885 unsigned long pages_to_free)886{887 unsigned long blocks_to_free, blocks_freed;888 889 pages_to_free = round_up(pages_to_free,890 VIRTIO_BALLOON_HINT_BLOCK_PAGES);891 blocks_to_free = pages_to_free / VIRTIO_BALLOON_HINT_BLOCK_PAGES;892 blocks_freed = return_free_pages_to_mm(vb, blocks_to_free);893 894 return blocks_freed * VIRTIO_BALLOON_HINT_BLOCK_PAGES;895}896 897static unsigned long virtio_balloon_shrinker_scan(struct shrinker *shrinker,898 struct shrink_control *sc)899{900 struct virtio_balloon *vb = shrinker->private_data;901 902 return shrink_free_pages(vb, sc->nr_to_scan);903}904 905static unsigned long virtio_balloon_shrinker_count(struct shrinker *shrinker,906 struct shrink_control *sc)907{908 struct virtio_balloon *vb = shrinker->private_data;909 910 return vb->num_free_page_blocks * VIRTIO_BALLOON_HINT_BLOCK_PAGES;911}912 913static int virtio_balloon_oom_notify(struct notifier_block *nb,914 unsigned long dummy, void *parm)915{916 struct virtio_balloon *vb = container_of(nb,917 struct virtio_balloon, oom_nb);918 unsigned long *freed = parm;919 920 *freed += leak_balloon(vb, VIRTIO_BALLOON_OOM_NR_PAGES) /921 VIRTIO_BALLOON_PAGES_PER_PAGE;922 update_balloon_size(vb);923 924 return NOTIFY_OK;925}926 927static void virtio_balloon_unregister_shrinker(struct virtio_balloon *vb)928{929 shrinker_free(vb->shrinker);930}931 932static int virtio_balloon_register_shrinker(struct virtio_balloon *vb)933{934 vb->shrinker = shrinker_alloc(0, "virtio-balloon");935 if (!vb->shrinker)936 return -ENOMEM;937 938 vb->shrinker->scan_objects = virtio_balloon_shrinker_scan;939 vb->shrinker->count_objects = virtio_balloon_shrinker_count;940 vb->shrinker->private_data = vb;941 942 shrinker_register(vb->shrinker);943 944 return 0;945}946 947static int virtballoon_probe(struct virtio_device *vdev)948{949 struct virtio_balloon *vb;950 int err;951 952 if (!vdev->config->get) {953 dev_err(&vdev->dev, "%s failure: config access disabled\n",954 __func__);955 return -EINVAL;956 }957 958 vdev->priv = vb = kzalloc(sizeof(*vb), GFP_KERNEL);959 if (!vb) {960 err = -ENOMEM;961 goto out;962 }963 964 INIT_WORK(&vb->update_balloon_stats_work, update_balloon_stats_func);965 INIT_WORK(&vb->update_balloon_size_work, update_balloon_size_func);966 spin_lock_init(&vb->stop_update_lock);967 mutex_init(&vb->balloon_lock);968 init_waitqueue_head(&vb->acked);969 vb->vdev = vdev;970 971 balloon_devinfo_init(&vb->vb_dev_info);972 973 err = init_vqs(vb);974 if (err)975 goto out_free_vb;976 977#ifdef CONFIG_BALLOON_COMPACTION978 vb->vb_dev_info.migratepage = virtballoon_migratepage;979#endif980 if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {981 /*982 * There is always one entry reserved for cmd id, so the ring983 * size needs to be at least two to report free page hints.984 */985 if (virtqueue_get_vring_size(vb->free_page_vq) < 2) {986 err = -ENOSPC;987 goto out_del_vqs;988 }989 vb->balloon_wq = alloc_workqueue("balloon-wq",990 WQ_FREEZABLE | WQ_CPU_INTENSIVE, 0);991 if (!vb->balloon_wq) {992 err = -ENOMEM;993 goto out_del_vqs;994 }995 INIT_WORK(&vb->report_free_page_work, report_free_page_func);996 vb->cmd_id_received_cache = VIRTIO_BALLOON_CMD_ID_STOP;997 vb->cmd_id_active = cpu_to_virtio32(vb->vdev,998 VIRTIO_BALLOON_CMD_ID_STOP);999 vb->cmd_id_stop = cpu_to_virtio32(vb->vdev,1000 VIRTIO_BALLOON_CMD_ID_STOP);1001 spin_lock_init(&vb->free_page_list_lock);1002 INIT_LIST_HEAD(&vb->free_page_list);1003 /*1004 * We're allowed to reuse any free pages, even if they are1005 * still to be processed by the host.1006 */1007 err = virtio_balloon_register_shrinker(vb);1008 if (err)1009 goto out_del_balloon_wq;1010 }1011 1012 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) {1013 vb->oom_nb.notifier_call = virtio_balloon_oom_notify;1014 vb->oom_nb.priority = VIRTIO_BALLOON_OOM_NOTIFY_PRIORITY;1015 err = register_oom_notifier(&vb->oom_nb);1016 if (err < 0)1017 goto out_unregister_shrinker;1018 }1019 1020 if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON)) {1021 /* Start with poison val of 0 representing general init */1022 __u32 poison_val = 0;1023 1024 /*1025 * Let the hypervisor know that we are expecting a1026 * specific value to be written back in balloon pages.1027 *1028 * If the PAGE_POISON value was larger than a byte we would1029 * need to byte swap poison_val here to guarantee it is1030 * little-endian. However for now it is a single byte so we1031 * can pass it as-is.1032 */1033 if (!want_init_on_free())1034 memset(&poison_val, PAGE_POISON, sizeof(poison_val));1035 1036 virtio_cwrite_le(vb->vdev, struct virtio_balloon_config,1037 poison_val, &poison_val);1038 }1039 1040 vb->pr_dev_info.report = virtballoon_free_page_report;1041 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING)) {1042 unsigned int capacity;1043 1044 capacity = virtqueue_get_vring_size(vb->reporting_vq);1045 if (capacity < PAGE_REPORTING_CAPACITY) {1046 err = -ENOSPC;1047 goto out_unregister_oom;1048 }1049 1050 /*1051 * The default page reporting order is @pageblock_order, which1052 * corresponds to 512MB in size on ARM64 when 64KB base page1053 * size is used. The page reporting won't be triggered if the1054 * freeing page can't come up with a free area like that huge.1055 * So we specify the page reporting order to 5, corresponding1056 * to 2MB. It helps to avoid THP splitting if 4KB base page1057 * size is used by host.1058 *1059 * Ideally, the page reporting order is selected based on the1060 * host's base page size. However, it needs more work to report1061 * that value. The hard-coded order would be fine currently.1062 */1063#if defined(CONFIG_ARM64) && defined(CONFIG_ARM64_64K_PAGES)1064 vb->pr_dev_info.order = 5;1065#endif1066 1067 err = page_reporting_register(&vb->pr_dev_info);1068 if (err)1069 goto out_unregister_oom;1070 }1071 1072 spin_lock_init(&vb->wakeup_lock);1073 1074 /*1075 * The virtio balloon itself can't wake up the device, but it is1076 * responsible for processing wakeup events passed up from the transport1077 * layer. Wakeup sources don't support nesting/chaining calls, so we use1078 * our own wakeup source to ensure wakeup events are properly handled1079 * without trampling on the transport layer's wakeup source.1080 */1081 device_set_wakeup_capable(&vb->vdev->dev, true);1082 1083 virtio_device_ready(vdev);1084 1085 if (towards_target(vb))1086 virtballoon_changed(vdev);1087 return 0;1088 1089out_unregister_oom:1090 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM))1091 unregister_oom_notifier(&vb->oom_nb);1092out_unregister_shrinker:1093 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))1094 virtio_balloon_unregister_shrinker(vb);1095out_del_balloon_wq:1096 if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))1097 destroy_workqueue(vb->balloon_wq);1098out_del_vqs:1099 vdev->config->del_vqs(vdev);1100out_free_vb:1101 kfree(vb);1102out:1103 return err;1104}1105 1106static void remove_common(struct virtio_balloon *vb)1107{1108 /* There might be pages left in the balloon: free them. */1109 while (vb->num_pages)1110 leak_balloon(vb, vb->num_pages);1111 update_balloon_size(vb);1112 1113 /* There might be free pages that are being reported: release them. */1114 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))1115 return_free_pages_to_mm(vb, ULONG_MAX);1116 1117 /* Now we reset the device so we can clean up the queues. */1118 virtio_reset_device(vb->vdev);1119 1120 vb->vdev->config->del_vqs(vb->vdev);1121}1122 1123static void virtballoon_remove(struct virtio_device *vdev)1124{1125 struct virtio_balloon *vb = vdev->priv;1126 1127 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING))1128 page_reporting_unregister(&vb->pr_dev_info);1129 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM))1130 unregister_oom_notifier(&vb->oom_nb);1131 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))1132 virtio_balloon_unregister_shrinker(vb);1133 spin_lock_irq(&vb->stop_update_lock);1134 vb->stop_update = true;1135 spin_unlock_irq(&vb->stop_update_lock);1136 cancel_work_sync(&vb->update_balloon_size_work);1137 cancel_work_sync(&vb->update_balloon_stats_work);1138 1139 if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {1140 cancel_work_sync(&vb->report_free_page_work);1141 destroy_workqueue(vb->balloon_wq);1142 }1143 1144 remove_common(vb);1145 kfree(vb);1146}1147 1148#ifdef CONFIG_PM_SLEEP1149static int virtballoon_freeze(struct virtio_device *vdev)1150{1151 struct virtio_balloon *vb = vdev->priv;1152 1153 /*1154 * The workqueue is already frozen by the PM core before this1155 * function is called.1156 */1157 remove_common(vb);1158 return 0;1159}1160 1161static int virtballoon_restore(struct virtio_device *vdev)1162{1163 struct virtio_balloon *vb = vdev->priv;1164 int ret;1165 1166 ret = init_vqs(vdev->priv);1167 if (ret)1168 return ret;1169 1170 virtio_device_ready(vdev);1171 1172 if (towards_target(vb))1173 virtballoon_changed(vdev);1174 update_balloon_size(vb);1175 return 0;1176}1177#endif1178 1179static int virtballoon_validate(struct virtio_device *vdev)1180{1181 /*1182 * Inform the hypervisor that our pages are poisoned or1183 * initialized. If we cannot do that then we should disable1184 * page reporting as it could potentially change the contents1185 * of our free pages.1186 */1187 if (!want_init_on_free() && !page_poisoning_enabled_static())1188 __virtio_clear_bit(vdev, VIRTIO_BALLOON_F_PAGE_POISON);1189 else if (!virtio_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON))1190 __virtio_clear_bit(vdev, VIRTIO_BALLOON_F_REPORTING);1191 1192 __virtio_clear_bit(vdev, VIRTIO_F_ACCESS_PLATFORM);1193 return 0;1194}1195 1196static unsigned int features[] = {1197 VIRTIO_BALLOON_F_MUST_TELL_HOST,1198 VIRTIO_BALLOON_F_STATS_VQ,1199 VIRTIO_BALLOON_F_DEFLATE_ON_OOM,1200 VIRTIO_BALLOON_F_FREE_PAGE_HINT,1201 VIRTIO_BALLOON_F_PAGE_POISON,1202 VIRTIO_BALLOON_F_REPORTING,1203};1204 1205static struct virtio_driver virtio_balloon_driver = {1206 .feature_table = features,1207 .feature_table_size = ARRAY_SIZE(features),1208 .driver.name = KBUILD_MODNAME,1209 .id_table = id_table,1210 .validate = virtballoon_validate,1211 .probe = virtballoon_probe,1212 .remove = virtballoon_remove,1213 .config_changed = virtballoon_changed,1214#ifdef CONFIG_PM_SLEEP1215 .freeze = virtballoon_freeze,1216 .restore = virtballoon_restore,1217#endif1218};1219 1220module_virtio_driver(virtio_balloon_driver);1221MODULE_DEVICE_TABLE(virtio, id_table);1222MODULE_DESCRIPTION("Virtio balloon driver");1223MODULE_LICENSE("GPL");1224