watchdog: pic32-dmt: Remove .owner field for driver
[linux/fpc-iii.git] / drivers / virtio / virtio_balloon.c
blob476c0e3a7150694b258e40787f303d6b46c29c17
1 /*
2 * Virtio balloon implementation, inspired by Dor Laor and Marcelo
3 * Tosatti's implementations.
5 * Copyright 2008 Rusty Russell IBM Corporation
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
22 #include <linux/virtio.h>
23 #include <linux/virtio_balloon.h>
24 #include <linux/swap.h>
25 #include <linux/workqueue.h>
26 #include <linux/delay.h>
27 #include <linux/slab.h>
28 #include <linux/module.h>
29 #include <linux/balloon_compaction.h>
30 #include <linux/oom.h>
31 #include <linux/wait.h>
32 #include <linux/mm.h>
35 * Balloon device works in 4K page units. So each page is pointed to by
36 * multiple balloon pages. All memory counters in this driver are in balloon
37 * page units.
39 #define VIRTIO_BALLOON_PAGES_PER_PAGE (unsigned)(PAGE_SIZE >> VIRTIO_BALLOON_PFN_SHIFT)
40 #define VIRTIO_BALLOON_ARRAY_PFNS_MAX 256
41 #define OOM_VBALLOON_DEFAULT_PAGES 256
42 #define VIRTBALLOON_OOM_NOTIFY_PRIORITY 80
44 static int oom_pages = OOM_VBALLOON_DEFAULT_PAGES;
45 module_param(oom_pages, int, S_IRUSR | S_IWUSR);
46 MODULE_PARM_DESC(oom_pages, "pages to free on OOM");
48 struct virtio_balloon {
49 struct virtio_device *vdev;
50 struct virtqueue *inflate_vq, *deflate_vq, *stats_vq;
52 /* The balloon servicing is delegated to a freezable workqueue. */
53 struct work_struct update_balloon_stats_work;
54 struct work_struct update_balloon_size_work;
56 /* Prevent updating balloon when it is being canceled. */
57 spinlock_t stop_update_lock;
58 bool stop_update;
60 /* Waiting for host to ack the pages we released. */
61 wait_queue_head_t acked;
63 /* Number of balloon pages we've told the Host we're not using. */
64 unsigned int num_pages;
66 * The pages we've told the Host we're not using are enqueued
67 * at vb_dev_info->pages list.
68 * Each page on this list adds VIRTIO_BALLOON_PAGES_PER_PAGE
69 * to num_pages above.
71 struct balloon_dev_info vb_dev_info;
73 /* Synchronize access/update to this struct virtio_balloon elements */
74 struct mutex balloon_lock;
76 /* The array of pfns we tell the Host about. */
77 unsigned int num_pfns;
78 __virtio32 pfns[VIRTIO_BALLOON_ARRAY_PFNS_MAX];
80 /* Memory statistics */
81 struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR];
83 /* To register callback in oom notifier call chain */
84 struct notifier_block nb;
87 static struct virtio_device_id id_table[] = {
88 { VIRTIO_ID_BALLOON, VIRTIO_DEV_ANY_ID },
89 { 0 },
92 static u32 page_to_balloon_pfn(struct page *page)
94 unsigned long pfn = page_to_pfn(page);
96 BUILD_BUG_ON(PAGE_SHIFT < VIRTIO_BALLOON_PFN_SHIFT);
97 /* Convert pfn from Linux page size to balloon page size. */
98 return pfn * VIRTIO_BALLOON_PAGES_PER_PAGE;
101 static struct page *balloon_pfn_to_page(u32 pfn)
103 BUG_ON(pfn % VIRTIO_BALLOON_PAGES_PER_PAGE);
104 return pfn_to_page(pfn / VIRTIO_BALLOON_PAGES_PER_PAGE);
107 static void balloon_ack(struct virtqueue *vq)
109 struct virtio_balloon *vb = vq->vdev->priv;
111 wake_up(&vb->acked);
114 static void tell_host(struct virtio_balloon *vb, struct virtqueue *vq)
116 struct scatterlist sg;
117 unsigned int len;
119 sg_init_one(&sg, vb->pfns, sizeof(vb->pfns[0]) * vb->num_pfns);
121 /* We should always be able to add one buffer to an empty queue. */
122 virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL);
123 virtqueue_kick(vq);
125 /* When host has read buffer, this completes via balloon_ack */
126 wait_event(vb->acked, virtqueue_get_buf(vq, &len));
130 static void set_page_pfns(struct virtio_balloon *vb,
131 __virtio32 pfns[], struct page *page)
133 unsigned int i;
135 /* Set balloon pfns pointing at this page.
136 * Note that the first pfn points at start of the page. */
137 for (i = 0; i < VIRTIO_BALLOON_PAGES_PER_PAGE; i++)
138 pfns[i] = cpu_to_virtio32(vb->vdev,
139 page_to_balloon_pfn(page) + i);
142 static unsigned fill_balloon(struct virtio_balloon *vb, size_t num)
144 struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info;
145 unsigned num_allocated_pages;
147 /* We can only do one array worth at a time. */
148 num = min(num, ARRAY_SIZE(vb->pfns));
150 mutex_lock(&vb->balloon_lock);
151 for (vb->num_pfns = 0; vb->num_pfns < num;
152 vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) {
153 struct page *page = balloon_page_enqueue(vb_dev_info);
155 if (!page) {
156 dev_info_ratelimited(&vb->vdev->dev,
157 "Out of puff! Can't get %u pages\n",
158 VIRTIO_BALLOON_PAGES_PER_PAGE);
159 /* Sleep for at least 1/5 of a second before retry. */
160 msleep(200);
161 break;
163 set_page_pfns(vb, vb->pfns + vb->num_pfns, page);
164 vb->num_pages += VIRTIO_BALLOON_PAGES_PER_PAGE;
165 if (!virtio_has_feature(vb->vdev,
166 VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
167 adjust_managed_page_count(page, -1);
170 num_allocated_pages = vb->num_pfns;
171 /* Did we get any? */
172 if (vb->num_pfns != 0)
173 tell_host(vb, vb->inflate_vq);
174 mutex_unlock(&vb->balloon_lock);
176 return num_allocated_pages;
179 static void release_pages_balloon(struct virtio_balloon *vb)
181 unsigned int i;
182 struct page *page;
184 /* Find pfns pointing at start of each page, get pages and free them. */
185 for (i = 0; i < vb->num_pfns; i += VIRTIO_BALLOON_PAGES_PER_PAGE) {
186 page = balloon_pfn_to_page(virtio32_to_cpu(vb->vdev,
187 vb->pfns[i]));
188 if (!virtio_has_feature(vb->vdev,
189 VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
190 adjust_managed_page_count(page, 1);
191 put_page(page); /* balloon reference */
195 static unsigned leak_balloon(struct virtio_balloon *vb, size_t num)
197 unsigned num_freed_pages;
198 struct page *page;
199 struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info;
201 /* We can only do one array worth at a time. */
202 num = min(num, ARRAY_SIZE(vb->pfns));
204 mutex_lock(&vb->balloon_lock);
205 for (vb->num_pfns = 0; vb->num_pfns < num;
206 vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) {
207 page = balloon_page_dequeue(vb_dev_info);
208 if (!page)
209 break;
210 set_page_pfns(vb, vb->pfns + vb->num_pfns, page);
211 vb->num_pages -= VIRTIO_BALLOON_PAGES_PER_PAGE;
214 num_freed_pages = vb->num_pfns;
216 * Note that if
217 * virtio_has_feature(vdev, VIRTIO_BALLOON_F_MUST_TELL_HOST);
218 * is true, we *have* to do it in this order
220 if (vb->num_pfns != 0)
221 tell_host(vb, vb->deflate_vq);
222 release_pages_balloon(vb);
223 mutex_unlock(&vb->balloon_lock);
224 return num_freed_pages;
227 static inline void update_stat(struct virtio_balloon *vb, int idx,
228 u16 tag, u64 val)
230 BUG_ON(idx >= VIRTIO_BALLOON_S_NR);
231 vb->stats[idx].tag = cpu_to_virtio16(vb->vdev, tag);
232 vb->stats[idx].val = cpu_to_virtio64(vb->vdev, val);
235 #define pages_to_bytes(x) ((u64)(x) << PAGE_SHIFT)
237 static void update_balloon_stats(struct virtio_balloon *vb)
239 unsigned long events[NR_VM_EVENT_ITEMS];
240 struct sysinfo i;
241 int idx = 0;
242 long available;
244 all_vm_events(events);
245 si_meminfo(&i);
247 available = si_mem_available();
249 update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_IN,
250 pages_to_bytes(events[PSWPIN]));
251 update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_OUT,
252 pages_to_bytes(events[PSWPOUT]));
253 update_stat(vb, idx++, VIRTIO_BALLOON_S_MAJFLT, events[PGMAJFAULT]);
254 update_stat(vb, idx++, VIRTIO_BALLOON_S_MINFLT, events[PGFAULT]);
255 update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMFREE,
256 pages_to_bytes(i.freeram));
257 update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMTOT,
258 pages_to_bytes(i.totalram));
259 update_stat(vb, idx++, VIRTIO_BALLOON_S_AVAIL,
260 pages_to_bytes(available));
264 * While most virtqueues communicate guest-initiated requests to the hypervisor,
265 * the stats queue operates in reverse. The driver initializes the virtqueue
266 * with a single buffer. From that point forward, all conversations consist of
267 * a hypervisor request (a call to this function) which directs us to refill
268 * the virtqueue with a fresh stats buffer. Since stats collection can sleep,
269 * we delegate the job to a freezable workqueue that will do the actual work via
270 * stats_handle_request().
272 static void stats_request(struct virtqueue *vq)
274 struct virtio_balloon *vb = vq->vdev->priv;
276 spin_lock(&vb->stop_update_lock);
277 if (!vb->stop_update)
278 queue_work(system_freezable_wq, &vb->update_balloon_stats_work);
279 spin_unlock(&vb->stop_update_lock);
282 static void stats_handle_request(struct virtio_balloon *vb)
284 struct virtqueue *vq;
285 struct scatterlist sg;
286 unsigned int len;
288 update_balloon_stats(vb);
290 vq = vb->stats_vq;
291 if (!virtqueue_get_buf(vq, &len))
292 return;
293 sg_init_one(&sg, vb->stats, sizeof(vb->stats));
294 virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL);
295 virtqueue_kick(vq);
298 static void virtballoon_changed(struct virtio_device *vdev)
300 struct virtio_balloon *vb = vdev->priv;
301 unsigned long flags;
303 spin_lock_irqsave(&vb->stop_update_lock, flags);
304 if (!vb->stop_update)
305 queue_work(system_freezable_wq, &vb->update_balloon_size_work);
306 spin_unlock_irqrestore(&vb->stop_update_lock, flags);
309 static inline s64 towards_target(struct virtio_balloon *vb)
311 s64 target;
312 u32 num_pages;
314 virtio_cread(vb->vdev, struct virtio_balloon_config, num_pages,
315 &num_pages);
317 /* Legacy balloon config space is LE, unlike all other devices. */
318 if (!virtio_has_feature(vb->vdev, VIRTIO_F_VERSION_1))
319 num_pages = le32_to_cpu((__force __le32)num_pages);
321 target = num_pages;
322 return target - vb->num_pages;
325 static void update_balloon_size(struct virtio_balloon *vb)
327 u32 actual = vb->num_pages;
329 /* Legacy balloon config space is LE, unlike all other devices. */
330 if (!virtio_has_feature(vb->vdev, VIRTIO_F_VERSION_1))
331 actual = (__force u32)cpu_to_le32(actual);
333 virtio_cwrite(vb->vdev, struct virtio_balloon_config, actual,
334 &actual);
338 * virtballoon_oom_notify - release pages when system is under severe
339 * memory pressure (called from out_of_memory())
340 * @self : notifier block struct
341 * @dummy: not used
342 * @parm : returned - number of freed pages
344 * The balancing of memory by use of the virtio balloon should not cause
345 * the termination of processes while there are pages in the balloon.
346 * If virtio balloon manages to release some memory, it will make the
347 * system return and retry the allocation that forced the OOM killer
348 * to run.
350 static int virtballoon_oom_notify(struct notifier_block *self,
351 unsigned long dummy, void *parm)
353 struct virtio_balloon *vb;
354 unsigned long *freed;
355 unsigned num_freed_pages;
357 vb = container_of(self, struct virtio_balloon, nb);
358 if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
359 return NOTIFY_OK;
361 freed = parm;
362 num_freed_pages = leak_balloon(vb, oom_pages);
363 update_balloon_size(vb);
364 *freed += num_freed_pages;
366 return NOTIFY_OK;
369 static void update_balloon_stats_func(struct work_struct *work)
371 struct virtio_balloon *vb;
373 vb = container_of(work, struct virtio_balloon,
374 update_balloon_stats_work);
375 stats_handle_request(vb);
378 static void update_balloon_size_func(struct work_struct *work)
380 struct virtio_balloon *vb;
381 s64 diff;
383 vb = container_of(work, struct virtio_balloon,
384 update_balloon_size_work);
385 diff = towards_target(vb);
387 if (diff > 0)
388 diff -= fill_balloon(vb, diff);
389 else if (diff < 0)
390 diff += leak_balloon(vb, -diff);
391 update_balloon_size(vb);
393 if (diff)
394 queue_work(system_freezable_wq, work);
397 static int init_vqs(struct virtio_balloon *vb)
399 struct virtqueue *vqs[3];
400 vq_callback_t *callbacks[] = { balloon_ack, balloon_ack, stats_request };
401 static const char * const names[] = { "inflate", "deflate", "stats" };
402 int err, nvqs;
405 * We expect two virtqueues: inflate and deflate, and
406 * optionally stat.
408 nvqs = virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ) ? 3 : 2;
409 err = vb->vdev->config->find_vqs(vb->vdev, nvqs, vqs, callbacks, names);
410 if (err)
411 return err;
413 vb->inflate_vq = vqs[0];
414 vb->deflate_vq = vqs[1];
415 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {
416 struct scatterlist sg;
417 vb->stats_vq = vqs[2];
420 * Prime this virtqueue with one buffer so the hypervisor can
421 * use it to signal us later (it can't be broken yet!).
423 sg_init_one(&sg, vb->stats, sizeof vb->stats);
424 if (virtqueue_add_outbuf(vb->stats_vq, &sg, 1, vb, GFP_KERNEL)
425 < 0)
426 BUG();
427 virtqueue_kick(vb->stats_vq);
429 return 0;
432 #ifdef CONFIG_BALLOON_COMPACTION
434 * virtballoon_migratepage - perform the balloon page migration on behalf of
435 * a compation thread. (called under page lock)
436 * @vb_dev_info: the balloon device
437 * @newpage: page that will replace the isolated page after migration finishes.
438 * @page : the isolated (old) page that is about to be migrated to newpage.
439 * @mode : compaction mode -- not used for balloon page migration.
441 * After a ballooned page gets isolated by compaction procedures, this is the
442 * function that performs the page migration on behalf of a compaction thread
443 * The page migration for virtio balloon is done in a simple swap fashion which
444 * follows these two macro steps:
445 * 1) insert newpage into vb->pages list and update the host about it;
446 * 2) update the host about the old page removed from vb->pages list;
448 * This function preforms the balloon page migration task.
449 * Called through balloon_mapping->a_ops->migratepage
451 static int virtballoon_migratepage(struct balloon_dev_info *vb_dev_info,
452 struct page *newpage, struct page *page, enum migrate_mode mode)
454 struct virtio_balloon *vb = container_of(vb_dev_info,
455 struct virtio_balloon, vb_dev_info);
456 unsigned long flags;
459 * In order to avoid lock contention while migrating pages concurrently
460 * to leak_balloon() or fill_balloon() we just give up the balloon_lock
461 * this turn, as it is easier to retry the page migration later.
462 * This also prevents fill_balloon() getting stuck into a mutex
463 * recursion in the case it ends up triggering memory compaction
464 * while it is attempting to inflate the ballon.
466 if (!mutex_trylock(&vb->balloon_lock))
467 return -EAGAIN;
469 get_page(newpage); /* balloon reference */
471 /* balloon's page migration 1st step -- inflate "newpage" */
472 spin_lock_irqsave(&vb_dev_info->pages_lock, flags);
473 balloon_page_insert(vb_dev_info, newpage);
474 vb_dev_info->isolated_pages--;
475 __count_vm_event(BALLOON_MIGRATE);
476 spin_unlock_irqrestore(&vb_dev_info->pages_lock, flags);
477 vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE;
478 set_page_pfns(vb, vb->pfns, newpage);
479 tell_host(vb, vb->inflate_vq);
481 /* balloon's page migration 2nd step -- deflate "page" */
482 balloon_page_delete(page);
483 vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE;
484 set_page_pfns(vb, vb->pfns, page);
485 tell_host(vb, vb->deflate_vq);
487 mutex_unlock(&vb->balloon_lock);
489 put_page(page); /* balloon reference */
491 return MIGRATEPAGE_SUCCESS;
493 #endif /* CONFIG_BALLOON_COMPACTION */
495 static int virtballoon_probe(struct virtio_device *vdev)
497 struct virtio_balloon *vb;
498 int err;
500 if (!vdev->config->get) {
501 dev_err(&vdev->dev, "%s failure: config access disabled\n",
502 __func__);
503 return -EINVAL;
506 vdev->priv = vb = kmalloc(sizeof(*vb), GFP_KERNEL);
507 if (!vb) {
508 err = -ENOMEM;
509 goto out;
512 INIT_WORK(&vb->update_balloon_stats_work, update_balloon_stats_func);
513 INIT_WORK(&vb->update_balloon_size_work, update_balloon_size_func);
514 spin_lock_init(&vb->stop_update_lock);
515 vb->stop_update = false;
516 vb->num_pages = 0;
517 mutex_init(&vb->balloon_lock);
518 init_waitqueue_head(&vb->acked);
519 vb->vdev = vdev;
521 balloon_devinfo_init(&vb->vb_dev_info);
522 #ifdef CONFIG_BALLOON_COMPACTION
523 vb->vb_dev_info.migratepage = virtballoon_migratepage;
524 #endif
526 err = init_vqs(vb);
527 if (err)
528 goto out_free_vb;
530 vb->nb.notifier_call = virtballoon_oom_notify;
531 vb->nb.priority = VIRTBALLOON_OOM_NOTIFY_PRIORITY;
532 err = register_oom_notifier(&vb->nb);
533 if (err < 0)
534 goto out_oom_notify;
536 virtio_device_ready(vdev);
538 return 0;
540 out_oom_notify:
541 vdev->config->del_vqs(vdev);
542 out_free_vb:
543 kfree(vb);
544 out:
545 return err;
548 static void remove_common(struct virtio_balloon *vb)
550 /* There might be pages left in the balloon: free them. */
551 while (vb->num_pages)
552 leak_balloon(vb, vb->num_pages);
553 update_balloon_size(vb);
555 /* Now we reset the device so we can clean up the queues. */
556 vb->vdev->config->reset(vb->vdev);
558 vb->vdev->config->del_vqs(vb->vdev);
561 static void virtballoon_remove(struct virtio_device *vdev)
563 struct virtio_balloon *vb = vdev->priv;
565 unregister_oom_notifier(&vb->nb);
567 spin_lock_irq(&vb->stop_update_lock);
568 vb->stop_update = true;
569 spin_unlock_irq(&vb->stop_update_lock);
570 cancel_work_sync(&vb->update_balloon_size_work);
571 cancel_work_sync(&vb->update_balloon_stats_work);
573 remove_common(vb);
574 kfree(vb);
577 #ifdef CONFIG_PM_SLEEP
578 static int virtballoon_freeze(struct virtio_device *vdev)
580 struct virtio_balloon *vb = vdev->priv;
583 * The workqueue is already frozen by the PM core before this
584 * function is called.
586 remove_common(vb);
587 return 0;
590 static int virtballoon_restore(struct virtio_device *vdev)
592 struct virtio_balloon *vb = vdev->priv;
593 int ret;
595 ret = init_vqs(vdev->priv);
596 if (ret)
597 return ret;
599 virtio_device_ready(vdev);
601 if (towards_target(vb))
602 virtballoon_changed(vdev);
603 update_balloon_size(vb);
604 return 0;
606 #endif
608 static unsigned int features[] = {
609 VIRTIO_BALLOON_F_MUST_TELL_HOST,
610 VIRTIO_BALLOON_F_STATS_VQ,
611 VIRTIO_BALLOON_F_DEFLATE_ON_OOM,
614 static struct virtio_driver virtio_balloon_driver = {
615 .feature_table = features,
616 .feature_table_size = ARRAY_SIZE(features),
617 .driver.name = KBUILD_MODNAME,
618 .driver.owner = THIS_MODULE,
619 .id_table = id_table,
620 .probe = virtballoon_probe,
621 .remove = virtballoon_remove,
622 .config_changed = virtballoon_changed,
623 #ifdef CONFIG_PM_SLEEP
624 .freeze = virtballoon_freeze,
625 .restore = virtballoon_restore,
626 #endif
629 module_virtio_driver(virtio_balloon_driver);
630 MODULE_DEVICE_TABLE(virtio, id_table);
631 MODULE_DESCRIPTION("Virtio balloon driver");
632 MODULE_LICENSE("GPL");