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
42 enum 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
51 enum virtio_balloon_config_read {
52 VIRTIO_BALLOON_CONFIG_READ_CMD_ID = 0,
53 };
54
55 struct 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
132 static const struct virtio_device_id id_table[] = {
133 { VIRTIO_ID_BALLOON, VIRTIO_DEV_ANY_ID },
134 { 0 },
135 };
136
page_to_balloon_pfn(struct page * page)137 static 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
start_wakeup_event(struct virtio_balloon * vb,u32 mask)146 static 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
process_wakeup_event(struct virtio_balloon * vb,u32 mask)159 static 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
finish_wakeup_event(struct virtio_balloon * vb)166 static 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
balloon_ack(struct virtqueue * vq)176 static void balloon_ack(struct virtqueue *vq)
177 {
178 struct virtio_balloon *vb = vq->vdev->priv;
179
180 wake_up(&vb->acked);
181 }
182
tell_host(struct virtio_balloon * vb,struct virtqueue * vq)183 static 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
virtballoon_free_page_report(struct page_reporting_dev_info * pr_dev_info,struct scatterlist * sg,unsigned int nents)199 static 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 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
set_page_pfns(struct virtio_balloon * vb,__virtio32 pfns[],struct page * page)226 static 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
fill_balloon(struct virtio_balloon * vb,size_t num)242 static 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
release_pages_balloon(struct virtio_balloon * vb,struct list_head * pages)292 static 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
leak_balloon(struct virtio_balloon * vb,size_t num)306 static 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
update_stat(struct virtio_balloon * vb,int idx,u16 tag,u64 val)342 static 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 */
update_balloon_vm_stats(struct virtio_balloon * vb)354 static 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 */
update_balloon_vm_stats(struct virtio_balloon * vb)395 static inline unsigned int update_balloon_vm_stats(struct virtio_balloon *vb)
396 {
397 return 0;
398 }
399 #endif /* CONFIG_VM_EVENT_COUNTERS */
400
update_balloon_stats(struct virtio_balloon * vb)401 static 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 */
stats_request(struct virtqueue * vq)434 static 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
stats_handle_request(struct virtio_balloon * vb)446 static 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
towards_target(struct virtio_balloon * vb)462 static 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. */
return_free_pages_to_mm(struct virtio_balloon * vb,unsigned long num_to_return)480 static 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
virtio_balloon_queue_free_page_work(struct virtio_balloon * vb)499 static 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
start_update_balloon_size(struct virtio_balloon * vb)512 static 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
virtballoon_changed(struct virtio_device * vdev)518 static 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
update_balloon_size(struct virtio_balloon * vb)531 static 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
update_balloon_stats_func(struct work_struct * work)540 static 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
update_balloon_size_func(struct work_struct * work)552 static 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
init_vqs(struct virtio_balloon * vb)578 static 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
virtio_balloon_cmd_id_received(struct virtio_balloon * vb)645 static 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
send_cmd_id_start(struct virtio_balloon * vb)658 static 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
send_cmd_id_stop(struct virtio_balloon * vb)677 static 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
get_free_page_and_send(struct virtio_balloon * vb)694 static 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
send_free_pages(struct virtio_balloon * vb)740 static 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
virtio_balloon_report_free_page(struct virtio_balloon * vb)769 static 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
report_free_page_func(struct work_struct * work)789 static 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 */
virtballoon_migratepage(struct balloon_dev_info * vb_dev_info,struct page * newpage,struct page * page,enum migrate_mode mode)825 static 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
shrink_free_pages(struct virtio_balloon * vb,unsigned long pages_to_free)880 static 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
virtio_balloon_shrinker_scan(struct shrinker * shrinker,struct shrink_control * sc)893 static 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
virtio_balloon_shrinker_count(struct shrinker * shrinker,struct shrink_control * sc)901 static 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
virtio_balloon_oom_notify(struct notifier_block * nb,unsigned long dummy,void * parm)909 static 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
virtio_balloon_unregister_shrinker(struct virtio_balloon * vb)923 static void virtio_balloon_unregister_shrinker(struct virtio_balloon *vb)
924 {
925 shrinker_free(vb->shrinker);
926 }
927
virtio_balloon_register_shrinker(struct virtio_balloon * vb)928 static 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
virtballoon_probe(struct virtio_device * vdev)943 static 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, 0);
987 if (!vb->balloon_wq) {
988 err = -ENOMEM;
989 goto out_del_vqs;
990 }
991 INIT_WORK(&vb->report_free_page_work, report_free_page_func);
992 vb->cmd_id_received_cache = VIRTIO_BALLOON_CMD_ID_STOP;
993 vb->cmd_id_active = cpu_to_virtio32(vb->vdev,
994 VIRTIO_BALLOON_CMD_ID_STOP);
995 vb->cmd_id_stop = cpu_to_virtio32(vb->vdev,
996 VIRTIO_BALLOON_CMD_ID_STOP);
997 spin_lock_init(&vb->free_page_list_lock);
998 INIT_LIST_HEAD(&vb->free_page_list);
999 /*
1000 * We're allowed to reuse any free pages, even if they are
1001 * still to be processed by the host.
1002 */
1003 err = virtio_balloon_register_shrinker(vb);
1004 if (err)
1005 goto out_del_balloon_wq;
1006 }
1007
1008 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) {
1009 vb->oom_nb.notifier_call = virtio_balloon_oom_notify;
1010 vb->oom_nb.priority = VIRTIO_BALLOON_OOM_NOTIFY_PRIORITY;
1011 err = register_oom_notifier(&vb->oom_nb);
1012 if (err < 0)
1013 goto out_unregister_shrinker;
1014 }
1015
1016 if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON)) {
1017 /* Start with poison val of 0 representing general init */
1018 __u32 poison_val = 0;
1019
1020 /*
1021 * Let the hypervisor know that we are expecting a
1022 * specific value to be written back in balloon pages.
1023 *
1024 * If the PAGE_POISON value was larger than a byte we would
1025 * need to byte swap poison_val here to guarantee it is
1026 * little-endian. However for now it is a single byte so we
1027 * can pass it as-is.
1028 */
1029 if (!want_init_on_free())
1030 memset(&poison_val, PAGE_POISON, sizeof(poison_val));
1031
1032 virtio_cwrite_le(vb->vdev, struct virtio_balloon_config,
1033 poison_val, &poison_val);
1034 }
1035
1036 vb->pr_dev_info.report = virtballoon_free_page_report;
1037 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING)) {
1038 unsigned int capacity;
1039
1040 capacity = virtqueue_get_vring_size(vb->reporting_vq);
1041 if (capacity < PAGE_REPORTING_CAPACITY) {
1042 err = -ENOSPC;
1043 goto out_unregister_oom;
1044 }
1045
1046 /*
1047 * The default page reporting order is @pageblock_order, which
1048 * corresponds to 512MB in size on ARM64 when 64KB base page
1049 * size is used. The page reporting won't be triggered if the
1050 * freeing page can't come up with a free area like that huge.
1051 * So we specify the page reporting order to 5, corresponding
1052 * to 2MB. It helps to avoid THP splitting if 4KB base page
1053 * size is used by host.
1054 *
1055 * Ideally, the page reporting order is selected based on the
1056 * host's base page size. However, it needs more work to report
1057 * that value. The hard-coded order would be fine currently.
1058 */
1059 #if defined(CONFIG_ARM64) && defined(CONFIG_ARM64_64K_PAGES)
1060 vb->pr_dev_info.order = 5;
1061 #endif
1062
1063 err = page_reporting_register(&vb->pr_dev_info);
1064 if (err)
1065 goto out_unregister_oom;
1066 }
1067
1068 spin_lock_init(&vb->wakeup_lock);
1069
1070 /*
1071 * The virtio balloon itself can't wake up the device, but it is
1072 * responsible for processing wakeup events passed up from the transport
1073 * layer. Wakeup sources don't support nesting/chaining calls, so we use
1074 * our own wakeup source to ensure wakeup events are properly handled
1075 * without trampling on the transport layer's wakeup source.
1076 */
1077 device_set_wakeup_capable(&vb->vdev->dev, true);
1078
1079 virtio_device_ready(vdev);
1080
1081 if (towards_target(vb))
1082 virtballoon_changed(vdev);
1083 return 0;
1084
1085 out_unregister_oom:
1086 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
1087 unregister_oom_notifier(&vb->oom_nb);
1088 out_unregister_shrinker:
1089 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
1090 virtio_balloon_unregister_shrinker(vb);
1091 out_del_balloon_wq:
1092 if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
1093 destroy_workqueue(vb->balloon_wq);
1094 out_del_vqs:
1095 vdev->config->del_vqs(vdev);
1096 out_free_vb:
1097 kfree(vb);
1098 out:
1099 return err;
1100 }
1101
remove_common(struct virtio_balloon * vb)1102 static void remove_common(struct virtio_balloon *vb)
1103 {
1104 /* There might be pages left in the balloon: free them. */
1105 while (vb->num_pages)
1106 leak_balloon(vb, vb->num_pages);
1107 update_balloon_size(vb);
1108
1109 /* There might be free pages that are being reported: release them. */
1110 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
1111 return_free_pages_to_mm(vb, ULONG_MAX);
1112
1113 /* Now we reset the device so we can clean up the queues. */
1114 virtio_reset_device(vb->vdev);
1115
1116 vb->vdev->config->del_vqs(vb->vdev);
1117 }
1118
virtballoon_remove(struct virtio_device * vdev)1119 static void virtballoon_remove(struct virtio_device *vdev)
1120 {
1121 struct virtio_balloon *vb = vdev->priv;
1122
1123 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING))
1124 page_reporting_unregister(&vb->pr_dev_info);
1125 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
1126 unregister_oom_notifier(&vb->oom_nb);
1127 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
1128 virtio_balloon_unregister_shrinker(vb);
1129 spin_lock_irq(&vb->stop_update_lock);
1130 vb->stop_update = true;
1131 spin_unlock_irq(&vb->stop_update_lock);
1132 cancel_work_sync(&vb->update_balloon_size_work);
1133 cancel_work_sync(&vb->update_balloon_stats_work);
1134
1135 if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {
1136 cancel_work_sync(&vb->report_free_page_work);
1137 destroy_workqueue(vb->balloon_wq);
1138 }
1139
1140 remove_common(vb);
1141 kfree(vb);
1142 }
1143
1144 #ifdef CONFIG_PM_SLEEP
virtballoon_freeze(struct virtio_device * vdev)1145 static int virtballoon_freeze(struct virtio_device *vdev)
1146 {
1147 struct virtio_balloon *vb = vdev->priv;
1148
1149 /*
1150 * The workqueue is already frozen by the PM core before this
1151 * function is called.
1152 */
1153 remove_common(vb);
1154 return 0;
1155 }
1156
virtballoon_restore(struct virtio_device * vdev)1157 static int virtballoon_restore(struct virtio_device *vdev)
1158 {
1159 struct virtio_balloon *vb = vdev->priv;
1160 int ret;
1161
1162 ret = init_vqs(vdev->priv);
1163 if (ret)
1164 return ret;
1165
1166 virtio_device_ready(vdev);
1167
1168 if (towards_target(vb))
1169 virtballoon_changed(vdev);
1170 update_balloon_size(vb);
1171 return 0;
1172 }
1173 #endif
1174
virtballoon_validate(struct virtio_device * vdev)1175 static int virtballoon_validate(struct virtio_device *vdev)
1176 {
1177 /*
1178 * Inform the hypervisor that our pages are poisoned or
1179 * initialized. If we cannot do that then we should disable
1180 * page reporting as it could potentially change the contents
1181 * of our free pages.
1182 */
1183 if (!want_init_on_free() && !page_poisoning_enabled_static())
1184 __virtio_clear_bit(vdev, VIRTIO_BALLOON_F_PAGE_POISON);
1185 else if (!virtio_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON))
1186 __virtio_clear_bit(vdev, VIRTIO_BALLOON_F_REPORTING);
1187
1188 __virtio_clear_bit(vdev, VIRTIO_F_ACCESS_PLATFORM);
1189 return 0;
1190 }
1191
1192 static unsigned int features[] = {
1193 VIRTIO_BALLOON_F_MUST_TELL_HOST,
1194 VIRTIO_BALLOON_F_STATS_VQ,
1195 VIRTIO_BALLOON_F_DEFLATE_ON_OOM,
1196 VIRTIO_BALLOON_F_FREE_PAGE_HINT,
1197 VIRTIO_BALLOON_F_PAGE_POISON,
1198 VIRTIO_BALLOON_F_REPORTING,
1199 };
1200
1201 static struct virtio_driver virtio_balloon_driver = {
1202 .feature_table = features,
1203 .feature_table_size = ARRAY_SIZE(features),
1204 .driver.name = KBUILD_MODNAME,
1205 .id_table = id_table,
1206 .validate = virtballoon_validate,
1207 .probe = virtballoon_probe,
1208 .remove = virtballoon_remove,
1209 .config_changed = virtballoon_changed,
1210 #ifdef CONFIG_PM_SLEEP
1211 .freeze = virtballoon_freeze,
1212 .restore = virtballoon_restore,
1213 #endif
1214 };
1215
1216 module_virtio_driver(virtio_balloon_driver);
1217 MODULE_DEVICE_TABLE(virtio, id_table);
1218 MODULE_DESCRIPTION("Virtio balloon driver");
1219 MODULE_LICENSE("GPL");
1220