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