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