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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
27
28
29
30#define VIRTIO_BALLOON_PAGES_PER_PAGE (unsigned)(PAGE_SIZE >> VIRTIO_BALLOON_PFN_SHIFT)
31#define VIRTIO_BALLOON_ARRAY_PFNS_MAX 256
32
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
39#define VIRTIO_BALLOON_HINT_BLOCK_ORDER (MAX_ORDER - 1)
40
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
46static struct vfsmount *balloon_mnt;
47#endif
48
49enum 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
58enum virtio_balloon_config_read {
59 VIRTIO_BALLOON_CONFIG_READ_CMD_ID = 0,
60};
61
62struct virtio_balloon {
63 struct virtio_device *vdev;
64 struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq;
65
66
67 struct workqueue_struct *balloon_wq;
68
69 struct work_struct report_free_page_work;
70
71
72 struct work_struct update_balloon_stats_work;
73 struct work_struct update_balloon_size_work;
74
75
76 spinlock_t stop_update_lock;
77 bool stop_update;
78
79 unsigned long config_read_bitmap;
80
81
82 struct list_head free_page_list;
83 spinlock_t free_page_list_lock;
84
85 unsigned long num_free_page_blocks;
86
87
88
89
90
91 u32 cmd_id_received_cache;
92
93 __virtio32 cmd_id_active;
94
95 __virtio32 cmd_id_stop;
96
97
98 wait_queue_head_t acked;
99
100
101 unsigned int num_pages;
102
103
104
105
106
107
108 struct balloon_dev_info vb_dev_info;
109
110
111 struct mutex balloon_lock;
112
113
114 unsigned int num_pfns;
115 __virtio32 pfns[VIRTIO_BALLOON_ARRAY_PFNS_MAX];
116
117
118 struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR];
119
120
121 struct shrinker shrinker;
122
123
124 struct notifier_block oom_nb;
125
126
127 struct virtqueue *reporting_vq;
128 struct page_reporting_dev_info pr_dev_info;
129};
130
131static struct virtio_device_id id_table[] = {
132 { VIRTIO_ID_BALLOON, VIRTIO_DEV_ANY_ID },
133 { 0 },
134};
135
136static 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
142 return pfn * VIRTIO_BALLOON_PAGES_PER_PAGE;
143}
144
145static void balloon_ack(struct virtqueue *vq)
146{
147 struct virtio_balloon *vb = vq->vdev->priv;
148
149 wake_up(&vb->acked);
150}
151
152static 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
160 virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL);
161 virtqueue_kick(vq);
162
163
164 wait_event(vb->acked, virtqueue_get_buf(vq, &len));
165
166}
167
168static 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
177 err = virtqueue_add_inbuf(vq, sg, nents, vb, GFP_NOWAIT | __GFP_NOWARN);
178
179
180
181
182
183
184 if (WARN_ON_ONCE(err))
185 return err;
186
187 virtqueue_kick(vq);
188
189
190 wait_event(vb->acked, virtqueue_get_buf(vq, &unused));
191
192 return 0;
193}
194
195static 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
204
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
211static 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
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
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
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
261static 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);
272 }
273}
274
275static 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
283 num = min(num, ARRAY_SIZE(vb->pfns));
284
285 mutex_lock(&vb->balloon_lock);
286
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
301
302
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
311static 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
321static 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
363
364
365
366
367
368
369
370static 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
380static 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
396static inline s64 towards_target(struct virtio_balloon *vb)
397{
398 s64 target;
399 u32 num_pages;
400
401 virtio_cread(vb->vdev, struct virtio_balloon_config, num_pages,
402 &num_pages);
403
404
405 if (!virtio_has_feature(vb->vdev, VIRTIO_F_VERSION_1))
406 num_pages = le32_to_cpu((__force __le32)num_pages);
407
408 target = num_pages;
409 return target - vb->num_pages;
410}
411
412
413static unsigned long return_free_pages_to_mm(struct virtio_balloon *vb,
414 unsigned long num_to_return)
415{
416 struct page *page;
417 unsigned long num_returned;
418
419 spin_lock_irq(&vb->free_page_list_lock);
420 for (num_returned = 0; num_returned < num_to_return; num_returned++) {
421 page = balloon_page_pop(&vb->free_page_list);
422 if (!page)
423 break;
424 free_pages((unsigned long)page_address(page),
425 VIRTIO_BALLOON_HINT_BLOCK_ORDER);
426 }
427 vb->num_free_page_blocks -= num_returned;
428 spin_unlock_irq(&vb->free_page_list_lock);
429
430 return num_returned;
431}
432
433static void virtio_balloon_queue_free_page_work(struct virtio_balloon *vb)
434{
435 if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
436 return;
437
438
439 if (test_and_set_bit(VIRTIO_BALLOON_CONFIG_READ_CMD_ID,
440 &vb->config_read_bitmap))
441 return;
442
443 queue_work(vb->balloon_wq, &vb->report_free_page_work);
444}
445
446static void virtballoon_changed(struct virtio_device *vdev)
447{
448 struct virtio_balloon *vb = vdev->priv;
449 unsigned long flags;
450
451 spin_lock_irqsave(&vb->stop_update_lock, flags);
452 if (!vb->stop_update) {
453 queue_work(system_freezable_wq,
454 &vb->update_balloon_size_work);
455 virtio_balloon_queue_free_page_work(vb);
456 }
457 spin_unlock_irqrestore(&vb->stop_update_lock, flags);
458}
459
460static void update_balloon_size(struct virtio_balloon *vb)
461{
462 u32 actual = vb->num_pages;
463
464
465 if (!virtio_has_feature(vb->vdev, VIRTIO_F_VERSION_1))
466 actual = (__force u32)cpu_to_le32(actual);
467
468 virtio_cwrite(vb->vdev, struct virtio_balloon_config, actual,
469 &actual);
470}
471
472static void update_balloon_stats_func(struct work_struct *work)
473{
474 struct virtio_balloon *vb;
475
476 vb = container_of(work, struct virtio_balloon,
477 update_balloon_stats_work);
478 stats_handle_request(vb);
479}
480
481static void update_balloon_size_func(struct work_struct *work)
482{
483 struct virtio_balloon *vb;
484 s64 diff;
485
486 vb = container_of(work, struct virtio_balloon,
487 update_balloon_size_work);
488 diff = towards_target(vb);
489
490 if (!diff)
491 return;
492
493 if (diff > 0)
494 diff -= fill_balloon(vb, diff);
495 else
496 diff += leak_balloon(vb, -diff);
497 update_balloon_size(vb);
498
499 if (diff)
500 queue_work(system_freezable_wq, work);
501}
502
503static int init_vqs(struct virtio_balloon *vb)
504{
505 struct virtqueue *vqs[VIRTIO_BALLOON_VQ_MAX];
506 vq_callback_t *callbacks[VIRTIO_BALLOON_VQ_MAX];
507 const char *names[VIRTIO_BALLOON_VQ_MAX];
508 int err;
509
510
511
512
513
514
515 callbacks[VIRTIO_BALLOON_VQ_INFLATE] = balloon_ack;
516 names[VIRTIO_BALLOON_VQ_INFLATE] = "inflate";
517 callbacks[VIRTIO_BALLOON_VQ_DEFLATE] = balloon_ack;
518 names[VIRTIO_BALLOON_VQ_DEFLATE] = "deflate";
519 callbacks[VIRTIO_BALLOON_VQ_STATS] = NULL;
520 names[VIRTIO_BALLOON_VQ_STATS] = NULL;
521 callbacks[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL;
522 names[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL;
523 names[VIRTIO_BALLOON_VQ_REPORTING] = NULL;
524
525 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {
526 names[VIRTIO_BALLOON_VQ_STATS] = "stats";
527 callbacks[VIRTIO_BALLOON_VQ_STATS] = stats_request;
528 }
529
530 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {
531 names[VIRTIO_BALLOON_VQ_FREE_PAGE] = "free_page_vq";
532 callbacks[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL;
533 }
534
535 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING)) {
536 names[VIRTIO_BALLOON_VQ_REPORTING] = "reporting_vq";
537 callbacks[VIRTIO_BALLOON_VQ_REPORTING] = balloon_ack;
538 }
539
540 err = vb->vdev->config->find_vqs(vb->vdev, VIRTIO_BALLOON_VQ_MAX,
541 vqs, callbacks, names, NULL, NULL);
542 if (err)
543 return err;
544
545 vb->inflate_vq = vqs[VIRTIO_BALLOON_VQ_INFLATE];
546 vb->deflate_vq = vqs[VIRTIO_BALLOON_VQ_DEFLATE];
547 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {
548 struct scatterlist sg;
549 unsigned int num_stats;
550 vb->stats_vq = vqs[VIRTIO_BALLOON_VQ_STATS];
551
552
553
554
555
556 num_stats = update_balloon_stats(vb);
557
558 sg_init_one(&sg, vb->stats, sizeof(vb->stats[0]) * num_stats);
559 err = virtqueue_add_outbuf(vb->stats_vq, &sg, 1, vb,
560 GFP_KERNEL);
561 if (err) {
562 dev_warn(&vb->vdev->dev, "%s: add stat_vq failed\n",
563 __func__);
564 return err;
565 }
566 virtqueue_kick(vb->stats_vq);
567 }
568
569 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
570 vb->free_page_vq = vqs[VIRTIO_BALLOON_VQ_FREE_PAGE];
571
572 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING))
573 vb->reporting_vq = vqs[VIRTIO_BALLOON_VQ_REPORTING];
574
575 return 0;
576}
577
578static u32 virtio_balloon_cmd_id_received(struct virtio_balloon *vb)
579{
580 if (test_and_clear_bit(VIRTIO_BALLOON_CONFIG_READ_CMD_ID,
581 &vb->config_read_bitmap))
582 virtio_cread(vb->vdev, struct virtio_balloon_config,
583 free_page_hint_cmd_id,
584 &vb->cmd_id_received_cache);
585
586 return vb->cmd_id_received_cache;
587}
588
589static int send_cmd_id_start(struct virtio_balloon *vb)
590{
591 struct scatterlist sg;
592 struct virtqueue *vq = vb->free_page_vq;
593 int err, unused;
594
595
596 while (virtqueue_get_buf(vq, &unused))
597 ;
598
599 vb->cmd_id_active = virtio32_to_cpu(vb->vdev,
600 virtio_balloon_cmd_id_received(vb));
601 sg_init_one(&sg, &vb->cmd_id_active, sizeof(vb->cmd_id_active));
602 err = virtqueue_add_outbuf(vq, &sg, 1, &vb->cmd_id_active, GFP_KERNEL);
603 if (!err)
604 virtqueue_kick(vq);
605 return err;
606}
607
608static int send_cmd_id_stop(struct virtio_balloon *vb)
609{
610 struct scatterlist sg;
611 struct virtqueue *vq = vb->free_page_vq;
612 int err, unused;
613
614
615 while (virtqueue_get_buf(vq, &unused))
616 ;
617
618 sg_init_one(&sg, &vb->cmd_id_stop, sizeof(vb->cmd_id_stop));
619 err = virtqueue_add_outbuf(vq, &sg, 1, &vb->cmd_id_stop, GFP_KERNEL);
620 if (!err)
621 virtqueue_kick(vq);
622 return err;
623}
624
625static int get_free_page_and_send(struct virtio_balloon *vb)
626{
627 struct virtqueue *vq = vb->free_page_vq;
628 struct page *page;
629 struct scatterlist sg;
630 int err, unused;
631 void *p;
632
633
634 while (virtqueue_get_buf(vq, &unused))
635 ;
636
637 page = alloc_pages(VIRTIO_BALLOON_FREE_PAGE_ALLOC_FLAG,
638 VIRTIO_BALLOON_HINT_BLOCK_ORDER);
639
640
641
642
643 if (!page)
644 return -EINTR;
645
646 p = page_address(page);
647 sg_init_one(&sg, p, VIRTIO_BALLOON_HINT_BLOCK_BYTES);
648
649 if (vq->num_free > 1) {
650 err = virtqueue_add_inbuf(vq, &sg, 1, p, GFP_KERNEL);
651 if (unlikely(err)) {
652 free_pages((unsigned long)p,
653 VIRTIO_BALLOON_HINT_BLOCK_ORDER);
654 return err;
655 }
656 virtqueue_kick(vq);
657 spin_lock_irq(&vb->free_page_list_lock);
658 balloon_page_push(&vb->free_page_list, page);
659 vb->num_free_page_blocks++;
660 spin_unlock_irq(&vb->free_page_list_lock);
661 } else {
662
663
664
665
666 free_pages((unsigned long)p, VIRTIO_BALLOON_HINT_BLOCK_ORDER);
667 }
668
669 return 0;
670}
671
672static int send_free_pages(struct virtio_balloon *vb)
673{
674 int err;
675 u32 cmd_id_active;
676
677 while (1) {
678
679
680
681
682 cmd_id_active = virtio32_to_cpu(vb->vdev, vb->cmd_id_active);
683 if (unlikely(cmd_id_active !=
684 virtio_balloon_cmd_id_received(vb)))
685 break;
686
687
688
689
690
691 err = get_free_page_and_send(vb);
692 if (err == -EINTR)
693 break;
694 else if (unlikely(err))
695 return err;
696 }
697
698 return 0;
699}
700
701static void virtio_balloon_report_free_page(struct virtio_balloon *vb)
702{
703 int err;
704 struct device *dev = &vb->vdev->dev;
705
706
707 err = send_cmd_id_start(vb);
708 if (unlikely(err))
709 dev_err(dev, "Failed to send a start id, err = %d\n", err);
710
711 err = send_free_pages(vb);
712 if (unlikely(err))
713 dev_err(dev, "Failed to send a free page, err = %d\n", err);
714
715
716 err = send_cmd_id_stop(vb);
717 if (unlikely(err))
718 dev_err(dev, "Failed to send a stop id, err = %d\n", err);
719}
720
721static void report_free_page_func(struct work_struct *work)
722{
723 struct virtio_balloon *vb = container_of(work, struct virtio_balloon,
724 report_free_page_work);
725 u32 cmd_id_received;
726
727 cmd_id_received = virtio_balloon_cmd_id_received(vb);
728 if (cmd_id_received == VIRTIO_BALLOON_CMD_ID_DONE) {
729
730 return_free_pages_to_mm(vb, ULONG_MAX);
731 } else if (cmd_id_received != VIRTIO_BALLOON_CMD_ID_STOP &&
732 cmd_id_received !=
733 virtio32_to_cpu(vb->vdev, vb->cmd_id_active)) {
734 virtio_balloon_report_free_page(vb);
735 }
736}
737
738#ifdef CONFIG_BALLOON_COMPACTION
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757static int virtballoon_migratepage(struct balloon_dev_info *vb_dev_info,
758 struct page *newpage, struct page *page, enum migrate_mode mode)
759{
760 struct virtio_balloon *vb = container_of(vb_dev_info,
761 struct virtio_balloon, vb_dev_info);
762 unsigned long flags;
763
764
765
766
767
768
769
770
771
772 if (!mutex_trylock(&vb->balloon_lock))
773 return -EAGAIN;
774
775 get_page(newpage);
776
777
778
779
780
781
782 if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM) &&
783 page_zone(page) != page_zone(newpage)) {
784 adjust_managed_page_count(page, 1);
785 adjust_managed_page_count(newpage, -1);
786 }
787
788
789 spin_lock_irqsave(&vb_dev_info->pages_lock, flags);
790 balloon_page_insert(vb_dev_info, newpage);
791 vb_dev_info->isolated_pages--;
792 __count_vm_event(BALLOON_MIGRATE);
793 spin_unlock_irqrestore(&vb_dev_info->pages_lock, flags);
794 vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE;
795 set_page_pfns(vb, vb->pfns, newpage);
796 tell_host(vb, vb->inflate_vq);
797
798
799 spin_lock_irqsave(&vb_dev_info->pages_lock, flags);
800 balloon_page_delete(page);
801 spin_unlock_irqrestore(&vb_dev_info->pages_lock, flags);
802 vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE;
803 set_page_pfns(vb, vb->pfns, page);
804 tell_host(vb, vb->deflate_vq);
805
806 mutex_unlock(&vb->balloon_lock);
807
808 put_page(page);
809
810 return MIGRATEPAGE_SUCCESS;
811}
812
813static int balloon_init_fs_context(struct fs_context *fc)
814{
815 return init_pseudo(fc, BALLOON_KVM_MAGIC) ? 0 : -ENOMEM;
816}
817
818static struct file_system_type balloon_fs = {
819 .name = "balloon-kvm",
820 .init_fs_context = balloon_init_fs_context,
821 .kill_sb = kill_anon_super,
822};
823
824#endif
825
826static unsigned long shrink_free_pages(struct virtio_balloon *vb,
827 unsigned long pages_to_free)
828{
829 unsigned long blocks_to_free, blocks_freed;
830
831 pages_to_free = round_up(pages_to_free,
832 VIRTIO_BALLOON_HINT_BLOCK_PAGES);
833 blocks_to_free = pages_to_free / VIRTIO_BALLOON_HINT_BLOCK_PAGES;
834 blocks_freed = return_free_pages_to_mm(vb, blocks_to_free);
835
836 return blocks_freed * VIRTIO_BALLOON_HINT_BLOCK_PAGES;
837}
838
839static unsigned long virtio_balloon_shrinker_scan(struct shrinker *shrinker,
840 struct shrink_control *sc)
841{
842 struct virtio_balloon *vb = container_of(shrinker,
843 struct virtio_balloon, shrinker);
844
845 return shrink_free_pages(vb, sc->nr_to_scan);
846}
847
848static unsigned long virtio_balloon_shrinker_count(struct shrinker *shrinker,
849 struct shrink_control *sc)
850{
851 struct virtio_balloon *vb = container_of(shrinker,
852 struct virtio_balloon, shrinker);
853
854 return vb->num_free_page_blocks * VIRTIO_BALLOON_HINT_BLOCK_PAGES;
855}
856
857static int virtio_balloon_oom_notify(struct notifier_block *nb,
858 unsigned long dummy, void *parm)
859{
860 struct virtio_balloon *vb = container_of(nb,
861 struct virtio_balloon, oom_nb);
862 unsigned long *freed = parm;
863
864 *freed += leak_balloon(vb, VIRTIO_BALLOON_OOM_NR_PAGES) /
865 VIRTIO_BALLOON_PAGES_PER_PAGE;
866 update_balloon_size(vb);
867
868 return NOTIFY_OK;
869}
870
871static void virtio_balloon_unregister_shrinker(struct virtio_balloon *vb)
872{
873 unregister_shrinker(&vb->shrinker);
874}
875
876static int virtio_balloon_register_shrinker(struct virtio_balloon *vb)
877{
878 vb->shrinker.scan_objects = virtio_balloon_shrinker_scan;
879 vb->shrinker.count_objects = virtio_balloon_shrinker_count;
880 vb->shrinker.seeks = DEFAULT_SEEKS;
881
882 return register_shrinker(&vb->shrinker);
883}
884
885static int virtballoon_probe(struct virtio_device *vdev)
886{
887 struct virtio_balloon *vb;
888 int err;
889
890 if (!vdev->config->get) {
891 dev_err(&vdev->dev, "%s failure: config access disabled\n",
892 __func__);
893 return -EINVAL;
894 }
895
896 vdev->priv = vb = kzalloc(sizeof(*vb), GFP_KERNEL);
897 if (!vb) {
898 err = -ENOMEM;
899 goto out;
900 }
901
902 INIT_WORK(&vb->update_balloon_stats_work, update_balloon_stats_func);
903 INIT_WORK(&vb->update_balloon_size_work, update_balloon_size_func);
904 spin_lock_init(&vb->stop_update_lock);
905 mutex_init(&vb->balloon_lock);
906 init_waitqueue_head(&vb->acked);
907 vb->vdev = vdev;
908
909 balloon_devinfo_init(&vb->vb_dev_info);
910
911 err = init_vqs(vb);
912 if (err)
913 goto out_free_vb;
914
915#ifdef CONFIG_BALLOON_COMPACTION
916 balloon_mnt = kern_mount(&balloon_fs);
917 if (IS_ERR(balloon_mnt)) {
918 err = PTR_ERR(balloon_mnt);
919 goto out_del_vqs;
920 }
921
922 vb->vb_dev_info.migratepage = virtballoon_migratepage;
923 vb->vb_dev_info.inode = alloc_anon_inode(balloon_mnt->mnt_sb);
924 if (IS_ERR(vb->vb_dev_info.inode)) {
925 err = PTR_ERR(vb->vb_dev_info.inode);
926 goto out_kern_unmount;
927 }
928 vb->vb_dev_info.inode->i_mapping->a_ops = &balloon_aops;
929#endif
930 if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {
931
932
933
934
935 if (virtqueue_get_vring_size(vb->free_page_vq) < 2) {
936 err = -ENOSPC;
937 goto out_iput;
938 }
939 vb->balloon_wq = alloc_workqueue("balloon-wq",
940 WQ_FREEZABLE | WQ_CPU_INTENSIVE, 0);
941 if (!vb->balloon_wq) {
942 err = -ENOMEM;
943 goto out_iput;
944 }
945 INIT_WORK(&vb->report_free_page_work, report_free_page_func);
946 vb->cmd_id_received_cache = VIRTIO_BALLOON_CMD_ID_STOP;
947 vb->cmd_id_active = cpu_to_virtio32(vb->vdev,
948 VIRTIO_BALLOON_CMD_ID_STOP);
949 vb->cmd_id_stop = cpu_to_virtio32(vb->vdev,
950 VIRTIO_BALLOON_CMD_ID_STOP);
951 spin_lock_init(&vb->free_page_list_lock);
952 INIT_LIST_HEAD(&vb->free_page_list);
953
954
955
956
957 err = virtio_balloon_register_shrinker(vb);
958 if (err)
959 goto out_del_balloon_wq;
960 }
961
962 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) {
963 vb->oom_nb.notifier_call = virtio_balloon_oom_notify;
964 vb->oom_nb.priority = VIRTIO_BALLOON_OOM_NOTIFY_PRIORITY;
965 err = register_oom_notifier(&vb->oom_nb);
966 if (err < 0)
967 goto out_unregister_shrinker;
968 }
969
970 if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON)) {
971
972 __u32 poison_val = 0;
973
974
975
976
977
978 if (!want_init_on_free())
979 memset(&poison_val, PAGE_POISON, sizeof(poison_val));
980
981 virtio_cwrite(vb->vdev, struct virtio_balloon_config,
982 poison_val, &poison_val);
983 }
984
985 vb->pr_dev_info.report = virtballoon_free_page_report;
986 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING)) {
987 unsigned int capacity;
988
989 capacity = virtqueue_get_vring_size(vb->reporting_vq);
990 if (capacity < PAGE_REPORTING_CAPACITY) {
991 err = -ENOSPC;
992 goto out_unregister_oom;
993 }
994
995 err = page_reporting_register(&vb->pr_dev_info);
996 if (err)
997 goto out_unregister_oom;
998 }
999
1000 virtio_device_ready(vdev);
1001
1002 if (towards_target(vb))
1003 virtballoon_changed(vdev);
1004 return 0;
1005
1006out_unregister_oom:
1007 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
1008 unregister_oom_notifier(&vb->oom_nb);
1009out_unregister_shrinker:
1010 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
1011 virtio_balloon_unregister_shrinker(vb);
1012out_del_balloon_wq:
1013 if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
1014 destroy_workqueue(vb->balloon_wq);
1015out_iput:
1016#ifdef CONFIG_BALLOON_COMPACTION
1017 iput(vb->vb_dev_info.inode);
1018out_kern_unmount:
1019 kern_unmount(balloon_mnt);
1020out_del_vqs:
1021#endif
1022 vdev->config->del_vqs(vdev);
1023out_free_vb:
1024 kfree(vb);
1025out:
1026 return err;
1027}
1028
1029static void remove_common(struct virtio_balloon *vb)
1030{
1031
1032 while (vb->num_pages)
1033 leak_balloon(vb, vb->num_pages);
1034 update_balloon_size(vb);
1035
1036
1037 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
1038 return_free_pages_to_mm(vb, ULONG_MAX);
1039
1040
1041 vb->vdev->config->reset(vb->vdev);
1042
1043 vb->vdev->config->del_vqs(vb->vdev);
1044}
1045
1046static void virtballoon_remove(struct virtio_device *vdev)
1047{
1048 struct virtio_balloon *vb = vdev->priv;
1049
1050 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING))
1051 page_reporting_unregister(&vb->pr_dev_info);
1052 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
1053 unregister_oom_notifier(&vb->oom_nb);
1054 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
1055 virtio_balloon_unregister_shrinker(vb);
1056 spin_lock_irq(&vb->stop_update_lock);
1057 vb->stop_update = true;
1058 spin_unlock_irq(&vb->stop_update_lock);
1059 cancel_work_sync(&vb->update_balloon_size_work);
1060 cancel_work_sync(&vb->update_balloon_stats_work);
1061
1062 if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {
1063 cancel_work_sync(&vb->report_free_page_work);
1064 destroy_workqueue(vb->balloon_wq);
1065 }
1066
1067 remove_common(vb);
1068#ifdef CONFIG_BALLOON_COMPACTION
1069 if (vb->vb_dev_info.inode)
1070 iput(vb->vb_dev_info.inode);
1071
1072 kern_unmount(balloon_mnt);
1073#endif
1074 kfree(vb);
1075}
1076
1077#ifdef CONFIG_PM_SLEEP
1078static int virtballoon_freeze(struct virtio_device *vdev)
1079{
1080 struct virtio_balloon *vb = vdev->priv;
1081
1082
1083
1084
1085
1086 remove_common(vb);
1087 return 0;
1088}
1089
1090static int virtballoon_restore(struct virtio_device *vdev)
1091{
1092 struct virtio_balloon *vb = vdev->priv;
1093 int ret;
1094
1095 ret = init_vqs(vdev->priv);
1096 if (ret)
1097 return ret;
1098
1099 virtio_device_ready(vdev);
1100
1101 if (towards_target(vb))
1102 virtballoon_changed(vdev);
1103 update_balloon_size(vb);
1104 return 0;
1105}
1106#endif
1107
1108static int virtballoon_validate(struct virtio_device *vdev)
1109{
1110
1111 if (!want_init_on_free() &&
1112 (IS_ENABLED(CONFIG_PAGE_POISONING_NO_SANITY) ||
1113 !page_poisoning_enabled()))
1114 __virtio_clear_bit(vdev, VIRTIO_BALLOON_F_PAGE_POISON);
1115
1116 __virtio_clear_bit(vdev, VIRTIO_F_IOMMU_PLATFORM);
1117 return 0;
1118}
1119
1120static unsigned int features[] = {
1121 VIRTIO_BALLOON_F_MUST_TELL_HOST,
1122 VIRTIO_BALLOON_F_STATS_VQ,
1123 VIRTIO_BALLOON_F_DEFLATE_ON_OOM,
1124 VIRTIO_BALLOON_F_FREE_PAGE_HINT,
1125 VIRTIO_BALLOON_F_PAGE_POISON,
1126 VIRTIO_BALLOON_F_REPORTING,
1127};
1128
1129static struct virtio_driver virtio_balloon_driver = {
1130 .feature_table = features,
1131 .feature_table_size = ARRAY_SIZE(features),
1132 .driver.name = KBUILD_MODNAME,
1133 .driver.owner = THIS_MODULE,
1134 .id_table = id_table,
1135 .validate = virtballoon_validate,
1136 .probe = virtballoon_probe,
1137 .remove = virtballoon_remove,
1138 .config_changed = virtballoon_changed,
1139#ifdef CONFIG_PM_SLEEP
1140 .freeze = virtballoon_freeze,
1141 .restore = virtballoon_restore,
1142#endif
1143};
1144
1145module_virtio_driver(virtio_balloon_driver);
1146MODULE_DEVICE_TABLE(virtio, id_table);
1147MODULE_DESCRIPTION("Virtio balloon driver");
1148MODULE_LICENSE("GPL");
1149