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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/wait.h>
18#include <linux/mm.h>
19#include <linux/mount.h>
20#include <linux/magic.h>
21#include <linux/pseudo_fs.h>
22
23
24
25
26
27
28#define VIRTIO_BALLOON_PAGES_PER_PAGE (unsigned)(PAGE_SIZE >> VIRTIO_BALLOON_PFN_SHIFT)
29#define VIRTIO_BALLOON_ARRAY_PFNS_MAX 256
30#define VIRTBALLOON_OOM_NOTIFY_PRIORITY 80
31
32#define VIRTIO_BALLOON_FREE_PAGE_ALLOC_FLAG (__GFP_NORETRY | __GFP_NOWARN | \
33 __GFP_NOMEMALLOC)
34
35#define VIRTIO_BALLOON_FREE_PAGE_ORDER (MAX_ORDER - 1)
36
37#define VIRTIO_BALLOON_FREE_PAGE_SIZE \
38 (1 << (VIRTIO_BALLOON_FREE_PAGE_ORDER + PAGE_SHIFT))
39
40#ifdef CONFIG_BALLOON_COMPACTION
41static struct vfsmount *balloon_mnt;
42#endif
43
44enum virtio_balloon_vq {
45 VIRTIO_BALLOON_VQ_INFLATE,
46 VIRTIO_BALLOON_VQ_DEFLATE,
47 VIRTIO_BALLOON_VQ_STATS,
48 VIRTIO_BALLOON_VQ_FREE_PAGE,
49 VIRTIO_BALLOON_VQ_MAX
50};
51
52enum virtio_balloon_config_read {
53 VIRTIO_BALLOON_CONFIG_READ_CMD_ID = 0,
54};
55
56struct virtio_balloon {
57 struct virtio_device *vdev;
58 struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq;
59
60
61 struct workqueue_struct *balloon_wq;
62
63 struct work_struct report_free_page_work;
64
65
66 struct work_struct update_balloon_stats_work;
67 struct work_struct update_balloon_size_work;
68
69
70 spinlock_t stop_update_lock;
71 bool stop_update;
72
73 unsigned long config_read_bitmap;
74
75
76 struct list_head free_page_list;
77 spinlock_t free_page_list_lock;
78
79 unsigned long num_free_page_blocks;
80
81
82
83
84
85 u32 cmd_id_received_cache;
86
87 __virtio32 cmd_id_active;
88
89 __virtio32 cmd_id_stop;
90
91
92 wait_queue_head_t acked;
93
94
95 unsigned int num_pages;
96
97
98
99
100
101
102 struct balloon_dev_info vb_dev_info;
103
104
105 struct mutex balloon_lock;
106
107
108 unsigned int num_pfns;
109 __virtio32 pfns[VIRTIO_BALLOON_ARRAY_PFNS_MAX];
110
111
112 struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR];
113
114
115 struct shrinker shrinker;
116};
117
118static struct virtio_device_id id_table[] = {
119 { VIRTIO_ID_BALLOON, VIRTIO_DEV_ANY_ID },
120 { 0 },
121};
122
123static u32 page_to_balloon_pfn(struct page *page)
124{
125 unsigned long pfn = page_to_pfn(page);
126
127 BUILD_BUG_ON(PAGE_SHIFT < VIRTIO_BALLOON_PFN_SHIFT);
128
129 return pfn * VIRTIO_BALLOON_PAGES_PER_PAGE;
130}
131
132static void balloon_ack(struct virtqueue *vq)
133{
134 struct virtio_balloon *vb = vq->vdev->priv;
135
136 wake_up(&vb->acked);
137}
138
139static void tell_host(struct virtio_balloon *vb, struct virtqueue *vq)
140{
141 struct scatterlist sg;
142 unsigned int len;
143
144 sg_init_one(&sg, vb->pfns, sizeof(vb->pfns[0]) * vb->num_pfns);
145
146
147 virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL);
148 virtqueue_kick(vq);
149
150
151 wait_event(vb->acked, virtqueue_get_buf(vq, &len));
152
153}
154
155static void set_page_pfns(struct virtio_balloon *vb,
156 __virtio32 pfns[], struct page *page)
157{
158 unsigned int i;
159
160
161
162
163
164 for (i = 0; i < VIRTIO_BALLOON_PAGES_PER_PAGE; i++)
165 pfns[i] = cpu_to_virtio32(vb->vdev,
166 page_to_balloon_pfn(page) + i);
167}
168
169static unsigned fill_balloon(struct virtio_balloon *vb, size_t num)
170{
171 unsigned num_allocated_pages;
172 unsigned num_pfns;
173 struct page *page;
174 LIST_HEAD(pages);
175
176
177 num = min(num, ARRAY_SIZE(vb->pfns));
178
179 for (num_pfns = 0; num_pfns < num;
180 num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) {
181 struct page *page = balloon_page_alloc();
182
183 if (!page) {
184 dev_info_ratelimited(&vb->vdev->dev,
185 "Out of puff! Can't get %u pages\n",
186 VIRTIO_BALLOON_PAGES_PER_PAGE);
187
188 msleep(200);
189 break;
190 }
191
192 balloon_page_push(&pages, page);
193 }
194
195 mutex_lock(&vb->balloon_lock);
196
197 vb->num_pfns = 0;
198
199 while ((page = balloon_page_pop(&pages))) {
200 balloon_page_enqueue(&vb->vb_dev_info, page);
201
202 set_page_pfns(vb, vb->pfns + vb->num_pfns, page);
203 vb->num_pages += VIRTIO_BALLOON_PAGES_PER_PAGE;
204 if (!virtio_has_feature(vb->vdev,
205 VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
206 adjust_managed_page_count(page, -1);
207 vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE;
208 }
209
210 num_allocated_pages = vb->num_pfns;
211
212 if (vb->num_pfns != 0)
213 tell_host(vb, vb->inflate_vq);
214 mutex_unlock(&vb->balloon_lock);
215
216 return num_allocated_pages;
217}
218
219static void release_pages_balloon(struct virtio_balloon *vb,
220 struct list_head *pages)
221{
222 struct page *page, *next;
223
224 list_for_each_entry_safe(page, next, pages, lru) {
225 if (!virtio_has_feature(vb->vdev,
226 VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
227 adjust_managed_page_count(page, 1);
228 list_del(&page->lru);
229 put_page(page);
230 }
231}
232
233static unsigned leak_balloon(struct virtio_balloon *vb, size_t num)
234{
235 unsigned num_freed_pages;
236 struct page *page;
237 struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info;
238 LIST_HEAD(pages);
239
240
241 num = min(num, ARRAY_SIZE(vb->pfns));
242
243 mutex_lock(&vb->balloon_lock);
244
245 num = min(num, (size_t)vb->num_pages);
246 for (vb->num_pfns = 0; vb->num_pfns < num;
247 vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) {
248 page = balloon_page_dequeue(vb_dev_info);
249 if (!page)
250 break;
251 set_page_pfns(vb, vb->pfns + vb->num_pfns, page);
252 list_add(&page->lru, &pages);
253 vb->num_pages -= VIRTIO_BALLOON_PAGES_PER_PAGE;
254 }
255
256 num_freed_pages = vb->num_pfns;
257
258
259
260
261
262 if (vb->num_pfns != 0)
263 tell_host(vb, vb->deflate_vq);
264 release_pages_balloon(vb, &pages);
265 mutex_unlock(&vb->balloon_lock);
266 return num_freed_pages;
267}
268
269static inline void update_stat(struct virtio_balloon *vb, int idx,
270 u16 tag, u64 val)
271{
272 BUG_ON(idx >= VIRTIO_BALLOON_S_NR);
273 vb->stats[idx].tag = cpu_to_virtio16(vb->vdev, tag);
274 vb->stats[idx].val = cpu_to_virtio64(vb->vdev, val);
275}
276
277#define pages_to_bytes(x) ((u64)(x) << PAGE_SHIFT)
278
279static unsigned int update_balloon_stats(struct virtio_balloon *vb)
280{
281 unsigned long events[NR_VM_EVENT_ITEMS];
282 struct sysinfo i;
283 unsigned int idx = 0;
284 long available;
285 unsigned long caches;
286
287 all_vm_events(events);
288 si_meminfo(&i);
289
290 available = si_mem_available();
291 caches = global_node_page_state(NR_FILE_PAGES);
292
293#ifdef CONFIG_VM_EVENT_COUNTERS
294 update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_IN,
295 pages_to_bytes(events[PSWPIN]));
296 update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_OUT,
297 pages_to_bytes(events[PSWPOUT]));
298 update_stat(vb, idx++, VIRTIO_BALLOON_S_MAJFLT, events[PGMAJFAULT]);
299 update_stat(vb, idx++, VIRTIO_BALLOON_S_MINFLT, events[PGFAULT]);
300#ifdef CONFIG_HUGETLB_PAGE
301 update_stat(vb, idx++, VIRTIO_BALLOON_S_HTLB_PGALLOC,
302 events[HTLB_BUDDY_PGALLOC]);
303 update_stat(vb, idx++, VIRTIO_BALLOON_S_HTLB_PGFAIL,
304 events[HTLB_BUDDY_PGALLOC_FAIL]);
305#endif
306#endif
307 update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMFREE,
308 pages_to_bytes(i.freeram));
309 update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMTOT,
310 pages_to_bytes(i.totalram));
311 update_stat(vb, idx++, VIRTIO_BALLOON_S_AVAIL,
312 pages_to_bytes(available));
313 update_stat(vb, idx++, VIRTIO_BALLOON_S_CACHES,
314 pages_to_bytes(caches));
315
316 return idx;
317}
318
319
320
321
322
323
324
325
326
327
328static void stats_request(struct virtqueue *vq)
329{
330 struct virtio_balloon *vb = vq->vdev->priv;
331
332 spin_lock(&vb->stop_update_lock);
333 if (!vb->stop_update)
334 queue_work(system_freezable_wq, &vb->update_balloon_stats_work);
335 spin_unlock(&vb->stop_update_lock);
336}
337
338static void stats_handle_request(struct virtio_balloon *vb)
339{
340 struct virtqueue *vq;
341 struct scatterlist sg;
342 unsigned int len, num_stats;
343
344 num_stats = update_balloon_stats(vb);
345
346 vq = vb->stats_vq;
347 if (!virtqueue_get_buf(vq, &len))
348 return;
349 sg_init_one(&sg, vb->stats, sizeof(vb->stats[0]) * num_stats);
350 virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL);
351 virtqueue_kick(vq);
352}
353
354static inline s64 towards_target(struct virtio_balloon *vb)
355{
356 s64 target;
357 u32 num_pages;
358
359 virtio_cread(vb->vdev, struct virtio_balloon_config, num_pages,
360 &num_pages);
361
362
363 if (!virtio_has_feature(vb->vdev, VIRTIO_F_VERSION_1))
364 num_pages = le32_to_cpu((__force __le32)num_pages);
365
366 target = num_pages;
367 return target - vb->num_pages;
368}
369
370
371static unsigned long return_free_pages_to_mm(struct virtio_balloon *vb,
372 unsigned long num_to_return)
373{
374 struct page *page;
375 unsigned long num_returned;
376
377 spin_lock_irq(&vb->free_page_list_lock);
378 for (num_returned = 0; num_returned < num_to_return; num_returned++) {
379 page = balloon_page_pop(&vb->free_page_list);
380 if (!page)
381 break;
382 free_pages((unsigned long)page_address(page),
383 VIRTIO_BALLOON_FREE_PAGE_ORDER);
384 }
385 vb->num_free_page_blocks -= num_returned;
386 spin_unlock_irq(&vb->free_page_list_lock);
387
388 return num_returned;
389}
390
391static void virtio_balloon_queue_free_page_work(struct virtio_balloon *vb)
392{
393 if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
394 return;
395
396
397 if (test_and_set_bit(VIRTIO_BALLOON_CONFIG_READ_CMD_ID,
398 &vb->config_read_bitmap))
399 return;
400
401 queue_work(vb->balloon_wq, &vb->report_free_page_work);
402}
403
404static void virtballoon_changed(struct virtio_device *vdev)
405{
406 struct virtio_balloon *vb = vdev->priv;
407 unsigned long flags;
408
409 spin_lock_irqsave(&vb->stop_update_lock, flags);
410 if (!vb->stop_update) {
411 queue_work(system_freezable_wq,
412 &vb->update_balloon_size_work);
413 virtio_balloon_queue_free_page_work(vb);
414 }
415 spin_unlock_irqrestore(&vb->stop_update_lock, flags);
416}
417
418static void update_balloon_size(struct virtio_balloon *vb)
419{
420 u32 actual = vb->num_pages;
421
422
423 if (!virtio_has_feature(vb->vdev, VIRTIO_F_VERSION_1))
424 actual = (__force u32)cpu_to_le32(actual);
425
426 virtio_cwrite(vb->vdev, struct virtio_balloon_config, actual,
427 &actual);
428}
429
430static void update_balloon_stats_func(struct work_struct *work)
431{
432 struct virtio_balloon *vb;
433
434 vb = container_of(work, struct virtio_balloon,
435 update_balloon_stats_work);
436 stats_handle_request(vb);
437}
438
439static void update_balloon_size_func(struct work_struct *work)
440{
441 struct virtio_balloon *vb;
442 s64 diff;
443
444 vb = container_of(work, struct virtio_balloon,
445 update_balloon_size_work);
446 diff = towards_target(vb);
447
448 if (!diff)
449 return;
450
451 if (diff > 0)
452 diff -= fill_balloon(vb, diff);
453 else
454 diff += leak_balloon(vb, -diff);
455 update_balloon_size(vb);
456
457 if (diff)
458 queue_work(system_freezable_wq, work);
459}
460
461static int init_vqs(struct virtio_balloon *vb)
462{
463 struct virtqueue *vqs[VIRTIO_BALLOON_VQ_MAX];
464 vq_callback_t *callbacks[VIRTIO_BALLOON_VQ_MAX];
465 const char *names[VIRTIO_BALLOON_VQ_MAX];
466 int err;
467
468
469
470
471
472
473 callbacks[VIRTIO_BALLOON_VQ_INFLATE] = balloon_ack;
474 names[VIRTIO_BALLOON_VQ_INFLATE] = "inflate";
475 callbacks[VIRTIO_BALLOON_VQ_DEFLATE] = balloon_ack;
476 names[VIRTIO_BALLOON_VQ_DEFLATE] = "deflate";
477 names[VIRTIO_BALLOON_VQ_STATS] = NULL;
478 names[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL;
479
480 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {
481 names[VIRTIO_BALLOON_VQ_STATS] = "stats";
482 callbacks[VIRTIO_BALLOON_VQ_STATS] = stats_request;
483 }
484
485 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {
486 names[VIRTIO_BALLOON_VQ_FREE_PAGE] = "free_page_vq";
487 callbacks[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL;
488 }
489
490 err = vb->vdev->config->find_vqs(vb->vdev, VIRTIO_BALLOON_VQ_MAX,
491 vqs, callbacks, names, NULL, NULL);
492 if (err)
493 return err;
494
495 vb->inflate_vq = vqs[VIRTIO_BALLOON_VQ_INFLATE];
496 vb->deflate_vq = vqs[VIRTIO_BALLOON_VQ_DEFLATE];
497 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {
498 struct scatterlist sg;
499 unsigned int num_stats;
500 vb->stats_vq = vqs[VIRTIO_BALLOON_VQ_STATS];
501
502
503
504
505
506 num_stats = update_balloon_stats(vb);
507
508 sg_init_one(&sg, vb->stats, sizeof(vb->stats[0]) * num_stats);
509 err = virtqueue_add_outbuf(vb->stats_vq, &sg, 1, vb,
510 GFP_KERNEL);
511 if (err) {
512 dev_warn(&vb->vdev->dev, "%s: add stat_vq failed\n",
513 __func__);
514 return err;
515 }
516 virtqueue_kick(vb->stats_vq);
517 }
518
519 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
520 vb->free_page_vq = vqs[VIRTIO_BALLOON_VQ_FREE_PAGE];
521
522 return 0;
523}
524
525static u32 virtio_balloon_cmd_id_received(struct virtio_balloon *vb)
526{
527 if (test_and_clear_bit(VIRTIO_BALLOON_CONFIG_READ_CMD_ID,
528 &vb->config_read_bitmap))
529 virtio_cread(vb->vdev, struct virtio_balloon_config,
530 free_page_report_cmd_id,
531 &vb->cmd_id_received_cache);
532
533 return vb->cmd_id_received_cache;
534}
535
536static int send_cmd_id_start(struct virtio_balloon *vb)
537{
538 struct scatterlist sg;
539 struct virtqueue *vq = vb->free_page_vq;
540 int err, unused;
541
542
543 while (virtqueue_get_buf(vq, &unused))
544 ;
545
546 vb->cmd_id_active = virtio32_to_cpu(vb->vdev,
547 virtio_balloon_cmd_id_received(vb));
548 sg_init_one(&sg, &vb->cmd_id_active, sizeof(vb->cmd_id_active));
549 err = virtqueue_add_outbuf(vq, &sg, 1, &vb->cmd_id_active, GFP_KERNEL);
550 if (!err)
551 virtqueue_kick(vq);
552 return err;
553}
554
555static int send_cmd_id_stop(struct virtio_balloon *vb)
556{
557 struct scatterlist sg;
558 struct virtqueue *vq = vb->free_page_vq;
559 int err, unused;
560
561
562 while (virtqueue_get_buf(vq, &unused))
563 ;
564
565 sg_init_one(&sg, &vb->cmd_id_stop, sizeof(vb->cmd_id_stop));
566 err = virtqueue_add_outbuf(vq, &sg, 1, &vb->cmd_id_stop, GFP_KERNEL);
567 if (!err)
568 virtqueue_kick(vq);
569 return err;
570}
571
572static int get_free_page_and_send(struct virtio_balloon *vb)
573{
574 struct virtqueue *vq = vb->free_page_vq;
575 struct page *page;
576 struct scatterlist sg;
577 int err, unused;
578 void *p;
579
580
581 while (virtqueue_get_buf(vq, &unused))
582 ;
583
584 page = alloc_pages(VIRTIO_BALLOON_FREE_PAGE_ALLOC_FLAG,
585 VIRTIO_BALLOON_FREE_PAGE_ORDER);
586
587
588
589
590 if (!page)
591 return -EINTR;
592
593 p = page_address(page);
594 sg_init_one(&sg, p, VIRTIO_BALLOON_FREE_PAGE_SIZE);
595
596 if (vq->num_free > 1) {
597 err = virtqueue_add_inbuf(vq, &sg, 1, p, GFP_KERNEL);
598 if (unlikely(err)) {
599 free_pages((unsigned long)p,
600 VIRTIO_BALLOON_FREE_PAGE_ORDER);
601 return err;
602 }
603 virtqueue_kick(vq);
604 spin_lock_irq(&vb->free_page_list_lock);
605 balloon_page_push(&vb->free_page_list, page);
606 vb->num_free_page_blocks++;
607 spin_unlock_irq(&vb->free_page_list_lock);
608 } else {
609
610
611
612
613 free_pages((unsigned long)p, VIRTIO_BALLOON_FREE_PAGE_ORDER);
614 }
615
616 return 0;
617}
618
619static int send_free_pages(struct virtio_balloon *vb)
620{
621 int err;
622 u32 cmd_id_active;
623
624 while (1) {
625
626
627
628
629 cmd_id_active = virtio32_to_cpu(vb->vdev, vb->cmd_id_active);
630 if (unlikely(cmd_id_active !=
631 virtio_balloon_cmd_id_received(vb)))
632 break;
633
634
635
636
637
638 err = get_free_page_and_send(vb);
639 if (err == -EINTR)
640 break;
641 else if (unlikely(err))
642 return err;
643 }
644
645 return 0;
646}
647
648static void virtio_balloon_report_free_page(struct virtio_balloon *vb)
649{
650 int err;
651 struct device *dev = &vb->vdev->dev;
652
653
654 err = send_cmd_id_start(vb);
655 if (unlikely(err))
656 dev_err(dev, "Failed to send a start id, err = %d\n", err);
657
658 err = send_free_pages(vb);
659 if (unlikely(err))
660 dev_err(dev, "Failed to send a free page, err = %d\n", err);
661
662
663 err = send_cmd_id_stop(vb);
664 if (unlikely(err))
665 dev_err(dev, "Failed to send a stop id, err = %d\n", err);
666}
667
668static void report_free_page_func(struct work_struct *work)
669{
670 struct virtio_balloon *vb = container_of(work, struct virtio_balloon,
671 report_free_page_work);
672 u32 cmd_id_received;
673
674 cmd_id_received = virtio_balloon_cmd_id_received(vb);
675 if (cmd_id_received == VIRTIO_BALLOON_CMD_ID_DONE) {
676
677 return_free_pages_to_mm(vb, ULONG_MAX);
678 } else if (cmd_id_received != VIRTIO_BALLOON_CMD_ID_STOP &&
679 cmd_id_received !=
680 virtio32_to_cpu(vb->vdev, vb->cmd_id_active)) {
681 virtio_balloon_report_free_page(vb);
682 }
683}
684
685#ifdef CONFIG_BALLOON_COMPACTION
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704static int virtballoon_migratepage(struct balloon_dev_info *vb_dev_info,
705 struct page *newpage, struct page *page, enum migrate_mode mode)
706{
707 struct virtio_balloon *vb = container_of(vb_dev_info,
708 struct virtio_balloon, vb_dev_info);
709 unsigned long flags;
710
711
712
713
714
715
716
717
718
719 if (!mutex_trylock(&vb->balloon_lock))
720 return -EAGAIN;
721
722 get_page(newpage);
723
724
725 spin_lock_irqsave(&vb_dev_info->pages_lock, flags);
726 balloon_page_insert(vb_dev_info, newpage);
727 vb_dev_info->isolated_pages--;
728 __count_vm_event(BALLOON_MIGRATE);
729 spin_unlock_irqrestore(&vb_dev_info->pages_lock, flags);
730 vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE;
731 set_page_pfns(vb, vb->pfns, newpage);
732 tell_host(vb, vb->inflate_vq);
733
734
735 spin_lock_irqsave(&vb_dev_info->pages_lock, flags);
736 balloon_page_delete(page);
737 spin_unlock_irqrestore(&vb_dev_info->pages_lock, flags);
738 vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE;
739 set_page_pfns(vb, vb->pfns, page);
740 tell_host(vb, vb->deflate_vq);
741
742 mutex_unlock(&vb->balloon_lock);
743
744 put_page(page);
745
746 return MIGRATEPAGE_SUCCESS;
747}
748
749static int balloon_init_fs_context(struct fs_context *fc)
750{
751 return init_pseudo(fc, BALLOON_KVM_MAGIC) ? 0 : -ENOMEM;
752}
753
754static struct file_system_type balloon_fs = {
755 .name = "balloon-kvm",
756 .init_fs_context = balloon_init_fs_context,
757 .kill_sb = kill_anon_super,
758};
759
760#endif
761
762static unsigned long shrink_free_pages(struct virtio_balloon *vb,
763 unsigned long pages_to_free)
764{
765 unsigned long blocks_to_free, blocks_freed;
766
767 pages_to_free = round_up(pages_to_free,
768 1 << VIRTIO_BALLOON_FREE_PAGE_ORDER);
769 blocks_to_free = pages_to_free >> VIRTIO_BALLOON_FREE_PAGE_ORDER;
770 blocks_freed = return_free_pages_to_mm(vb, blocks_to_free);
771
772 return blocks_freed << VIRTIO_BALLOON_FREE_PAGE_ORDER;
773}
774
775static unsigned long shrink_balloon_pages(struct virtio_balloon *vb,
776 unsigned long pages_to_free)
777{
778 unsigned long pages_freed = 0;
779
780
781
782
783
784
785 while (vb->num_pages && pages_to_free) {
786 pages_freed += leak_balloon(vb, pages_to_free) /
787 VIRTIO_BALLOON_PAGES_PER_PAGE;
788 pages_to_free -= pages_freed;
789 }
790 update_balloon_size(vb);
791
792 return pages_freed;
793}
794
795static unsigned long virtio_balloon_shrinker_scan(struct shrinker *shrinker,
796 struct shrink_control *sc)
797{
798 unsigned long pages_to_free, pages_freed = 0;
799 struct virtio_balloon *vb = container_of(shrinker,
800 struct virtio_balloon, shrinker);
801
802 pages_to_free = sc->nr_to_scan * VIRTIO_BALLOON_PAGES_PER_PAGE;
803
804 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
805 pages_freed = shrink_free_pages(vb, pages_to_free);
806
807 if (pages_freed >= pages_to_free)
808 return pages_freed;
809
810 pages_freed += shrink_balloon_pages(vb, pages_to_free - pages_freed);
811
812 return pages_freed;
813}
814
815static unsigned long virtio_balloon_shrinker_count(struct shrinker *shrinker,
816 struct shrink_control *sc)
817{
818 struct virtio_balloon *vb = container_of(shrinker,
819 struct virtio_balloon, shrinker);
820 unsigned long count;
821
822 count = vb->num_pages / VIRTIO_BALLOON_PAGES_PER_PAGE;
823 count += vb->num_free_page_blocks >> VIRTIO_BALLOON_FREE_PAGE_ORDER;
824
825 return count;
826}
827
828static void virtio_balloon_unregister_shrinker(struct virtio_balloon *vb)
829{
830 unregister_shrinker(&vb->shrinker);
831}
832
833static int virtio_balloon_register_shrinker(struct virtio_balloon *vb)
834{
835 vb->shrinker.scan_objects = virtio_balloon_shrinker_scan;
836 vb->shrinker.count_objects = virtio_balloon_shrinker_count;
837 vb->shrinker.seeks = DEFAULT_SEEKS;
838
839 return register_shrinker(&vb->shrinker);
840}
841
842static int virtballoon_probe(struct virtio_device *vdev)
843{
844 struct virtio_balloon *vb;
845 __u32 poison_val;
846 int err;
847
848 if (!vdev->config->get) {
849 dev_err(&vdev->dev, "%s failure: config access disabled\n",
850 __func__);
851 return -EINVAL;
852 }
853
854 vdev->priv = vb = kzalloc(sizeof(*vb), GFP_KERNEL);
855 if (!vb) {
856 err = -ENOMEM;
857 goto out;
858 }
859
860 INIT_WORK(&vb->update_balloon_stats_work, update_balloon_stats_func);
861 INIT_WORK(&vb->update_balloon_size_work, update_balloon_size_func);
862 spin_lock_init(&vb->stop_update_lock);
863 mutex_init(&vb->balloon_lock);
864 init_waitqueue_head(&vb->acked);
865 vb->vdev = vdev;
866
867 balloon_devinfo_init(&vb->vb_dev_info);
868
869 err = init_vqs(vb);
870 if (err)
871 goto out_free_vb;
872
873#ifdef CONFIG_BALLOON_COMPACTION
874 balloon_mnt = kern_mount(&balloon_fs);
875 if (IS_ERR(balloon_mnt)) {
876 err = PTR_ERR(balloon_mnt);
877 goto out_del_vqs;
878 }
879
880 vb->vb_dev_info.migratepage = virtballoon_migratepage;
881 vb->vb_dev_info.inode = alloc_anon_inode(balloon_mnt->mnt_sb);
882 if (IS_ERR(vb->vb_dev_info.inode)) {
883 err = PTR_ERR(vb->vb_dev_info.inode);
884 kern_unmount(balloon_mnt);
885 goto out_del_vqs;
886 }
887 vb->vb_dev_info.inode->i_mapping->a_ops = &balloon_aops;
888#endif
889 if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {
890
891
892
893
894 if (virtqueue_get_vring_size(vb->free_page_vq) < 2) {
895 err = -ENOSPC;
896 goto out_del_vqs;
897 }
898 vb->balloon_wq = alloc_workqueue("balloon-wq",
899 WQ_FREEZABLE | WQ_CPU_INTENSIVE, 0);
900 if (!vb->balloon_wq) {
901 err = -ENOMEM;
902 goto out_del_vqs;
903 }
904 INIT_WORK(&vb->report_free_page_work, report_free_page_func);
905 vb->cmd_id_received_cache = VIRTIO_BALLOON_CMD_ID_STOP;
906 vb->cmd_id_active = cpu_to_virtio32(vb->vdev,
907 VIRTIO_BALLOON_CMD_ID_STOP);
908 vb->cmd_id_stop = cpu_to_virtio32(vb->vdev,
909 VIRTIO_BALLOON_CMD_ID_STOP);
910 spin_lock_init(&vb->free_page_list_lock);
911 INIT_LIST_HEAD(&vb->free_page_list);
912 if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON)) {
913 memset(&poison_val, PAGE_POISON, sizeof(poison_val));
914 virtio_cwrite(vb->vdev, struct virtio_balloon_config,
915 poison_val, &poison_val);
916 }
917 }
918
919
920
921
922 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) {
923 err = virtio_balloon_register_shrinker(vb);
924 if (err)
925 goto out_del_balloon_wq;
926 }
927 virtio_device_ready(vdev);
928
929 if (towards_target(vb))
930 virtballoon_changed(vdev);
931 return 0;
932
933out_del_balloon_wq:
934 if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
935 destroy_workqueue(vb->balloon_wq);
936out_del_vqs:
937 vdev->config->del_vqs(vdev);
938out_free_vb:
939 kfree(vb);
940out:
941 return err;
942}
943
944static void remove_common(struct virtio_balloon *vb)
945{
946
947 while (vb->num_pages)
948 leak_balloon(vb, vb->num_pages);
949 update_balloon_size(vb);
950
951
952 vb->vdev->config->reset(vb->vdev);
953
954 vb->vdev->config->del_vqs(vb->vdev);
955}
956
957static void virtballoon_remove(struct virtio_device *vdev)
958{
959 struct virtio_balloon *vb = vdev->priv;
960
961 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
962 virtio_balloon_unregister_shrinker(vb);
963 spin_lock_irq(&vb->stop_update_lock);
964 vb->stop_update = true;
965 spin_unlock_irq(&vb->stop_update_lock);
966 cancel_work_sync(&vb->update_balloon_size_work);
967 cancel_work_sync(&vb->update_balloon_stats_work);
968
969 if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {
970 cancel_work_sync(&vb->report_free_page_work);
971 destroy_workqueue(vb->balloon_wq);
972 }
973
974 remove_common(vb);
975#ifdef CONFIG_BALLOON_COMPACTION
976 if (vb->vb_dev_info.inode)
977 iput(vb->vb_dev_info.inode);
978
979 kern_unmount(balloon_mnt);
980#endif
981 kfree(vb);
982}
983
984#ifdef CONFIG_PM_SLEEP
985static int virtballoon_freeze(struct virtio_device *vdev)
986{
987 struct virtio_balloon *vb = vdev->priv;
988
989
990
991
992
993 remove_common(vb);
994 return 0;
995}
996
997static int virtballoon_restore(struct virtio_device *vdev)
998{
999 struct virtio_balloon *vb = vdev->priv;
1000 int ret;
1001
1002 ret = init_vqs(vdev->priv);
1003 if (ret)
1004 return ret;
1005
1006 virtio_device_ready(vdev);
1007
1008 if (towards_target(vb))
1009 virtballoon_changed(vdev);
1010 update_balloon_size(vb);
1011 return 0;
1012}
1013#endif
1014
1015static int virtballoon_validate(struct virtio_device *vdev)
1016{
1017 if (!page_poisoning_enabled())
1018 __virtio_clear_bit(vdev, VIRTIO_BALLOON_F_PAGE_POISON);
1019
1020 __virtio_clear_bit(vdev, VIRTIO_F_IOMMU_PLATFORM);
1021 return 0;
1022}
1023
1024static unsigned int features[] = {
1025 VIRTIO_BALLOON_F_MUST_TELL_HOST,
1026 VIRTIO_BALLOON_F_STATS_VQ,
1027 VIRTIO_BALLOON_F_DEFLATE_ON_OOM,
1028 VIRTIO_BALLOON_F_FREE_PAGE_HINT,
1029 VIRTIO_BALLOON_F_PAGE_POISON,
1030};
1031
1032static struct virtio_driver virtio_balloon_driver = {
1033 .feature_table = features,
1034 .feature_table_size = ARRAY_SIZE(features),
1035 .driver.name = KBUILD_MODNAME,
1036 .driver.owner = THIS_MODULE,
1037 .id_table = id_table,
1038 .validate = virtballoon_validate,
1039 .probe = virtballoon_probe,
1040 .remove = virtballoon_remove,
1041 .config_changed = virtballoon_changed,
1042#ifdef CONFIG_PM_SLEEP
1043 .freeze = virtballoon_freeze,
1044 .restore = virtballoon_restore,
1045#endif
1046};
1047
1048module_virtio_driver(virtio_balloon_driver);
1049MODULE_DEVICE_TABLE(virtio, id_table);
1050MODULE_DESCRIPTION("Virtio balloon driver");
1051MODULE_LICENSE("GPL");
1052