Commit | Line | Data |
---|---|---|
1e214a5c SL |
1 | /* |
2 | * Virtio balloon implementation, inspired by Dor Laor and Marcelo | |
6b35e407 RR |
3 | * Tosatti's implementations. |
4 | * | |
5 | * Copyright 2008 Rusty Russell IBM Corporation | |
6 | * | |
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. | |
11 | * | |
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. | |
16 | * | |
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 | |
20 | */ | |
1e214a5c | 21 | |
6b35e407 RR |
22 | #include <linux/virtio.h> |
23 | #include <linux/virtio_balloon.h> | |
24 | #include <linux/swap.h> | |
25 | #include <linux/kthread.h> | |
26 | #include <linux/freezer.h> | |
6659a0f0 | 27 | #include <linux/delay.h> |
5a0e3ad6 | 28 | #include <linux/slab.h> |
b5a2c4f1 | 29 | #include <linux/module.h> |
6b35e407 | 30 | |
3ccc9372 MT |
31 | /* |
32 | * Balloon device works in 4K page units. So each page is pointed to by | |
33 | * multiple balloon pages. All memory counters in this driver are in balloon | |
34 | * page units. | |
35 | */ | |
36 | #define VIRTIO_BALLOON_PAGES_PER_PAGE (PAGE_SIZE >> VIRTIO_BALLOON_PFN_SHIFT) | |
37 | ||
6b35e407 RR |
38 | struct virtio_balloon |
39 | { | |
40 | struct virtio_device *vdev; | |
9564e138 | 41 | struct virtqueue *inflate_vq, *deflate_vq, *stats_vq; |
6b35e407 RR |
42 | |
43 | /* Where the ballooning thread waits for config to change. */ | |
44 | wait_queue_head_t config_change; | |
45 | ||
46 | /* The thread servicing the balloon. */ | |
47 | struct task_struct *thread; | |
48 | ||
49 | /* Waiting for host to ack the pages we released. */ | |
50 | struct completion acked; | |
51 | ||
3ccc9372 | 52 | /* Number of balloon pages we've told the Host we're not using. */ |
6b35e407 | 53 | unsigned int num_pages; |
3ccc9372 MT |
54 | /* |
55 | * The pages we've told the Host we're not using. | |
56 | * Each page on this list adds VIRTIO_BALLOON_PAGES_PER_PAGE | |
57 | * to num_pages above. | |
58 | */ | |
6b35e407 RR |
59 | struct list_head pages; |
60 | ||
61 | /* The array of pfns we tell the Host about. */ | |
62 | unsigned int num_pfns; | |
63 | u32 pfns[256]; | |
9564e138 AL |
64 | |
65 | /* Memory statistics */ | |
1f34c71a | 66 | int need_stats_update; |
9564e138 | 67 | struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR]; |
6b35e407 RR |
68 | }; |
69 | ||
70 | static struct virtio_device_id id_table[] = { | |
71 | { VIRTIO_ID_BALLOON, VIRTIO_DEV_ANY_ID }, | |
72 | { 0 }, | |
73 | }; | |
74 | ||
1b4aa2fa HB |
75 | static u32 page_to_balloon_pfn(struct page *page) |
76 | { | |
77 | unsigned long pfn = page_to_pfn(page); | |
78 | ||
79 | BUILD_BUG_ON(PAGE_SHIFT < VIRTIO_BALLOON_PFN_SHIFT); | |
80 | /* Convert pfn from Linux page size to balloon page size. */ | |
3ccc9372 MT |
81 | return pfn * VIRTIO_BALLOON_PAGES_PER_PAGE; |
82 | } | |
83 | ||
84 | static struct page *balloon_pfn_to_page(u32 pfn) | |
85 | { | |
86 | BUG_ON(pfn % VIRTIO_BALLOON_PAGES_PER_PAGE); | |
87 | return pfn_to_page(pfn / VIRTIO_BALLOON_PAGES_PER_PAGE); | |
1b4aa2fa HB |
88 | } |
89 | ||
6b35e407 RR |
90 | static void balloon_ack(struct virtqueue *vq) |
91 | { | |
92 | struct virtio_balloon *vb; | |
93 | unsigned int len; | |
94 | ||
946cfe0e | 95 | vb = virtqueue_get_buf(vq, &len); |
6b35e407 RR |
96 | if (vb) |
97 | complete(&vb->acked); | |
98 | } | |
99 | ||
100 | static void tell_host(struct virtio_balloon *vb, struct virtqueue *vq) | |
101 | { | |
102 | struct scatterlist sg; | |
103 | ||
104 | sg_init_one(&sg, vb->pfns, sizeof(vb->pfns[0]) * vb->num_pfns); | |
105 | ||
106 | init_completion(&vb->acked); | |
107 | ||
108 | /* We should always be able to add one buffer to an empty queue. */ | |
f96fde41 | 109 | if (virtqueue_add_buf(vq, &sg, 1, 0, vb, GFP_KERNEL) < 0) |
6b35e407 | 110 | BUG(); |
946cfe0e | 111 | virtqueue_kick(vq); |
6b35e407 RR |
112 | |
113 | /* When host has read buffer, this completes via balloon_ack */ | |
114 | wait_for_completion(&vb->acked); | |
115 | } | |
116 | ||
3ccc9372 MT |
117 | static void set_page_pfns(u32 pfns[], struct page *page) |
118 | { | |
119 | unsigned int i; | |
120 | ||
121 | /* Set balloon pfns pointing at this page. | |
122 | * Note that the first pfn points at start of the page. */ | |
123 | for (i = 0; i < VIRTIO_BALLOON_PAGES_PER_PAGE; i++) | |
124 | pfns[i] = page_to_balloon_pfn(page) + i; | |
125 | } | |
126 | ||
6b35e407 RR |
127 | static void fill_balloon(struct virtio_balloon *vb, size_t num) |
128 | { | |
129 | /* We can only do one array worth at a time. */ | |
130 | num = min(num, ARRAY_SIZE(vb->pfns)); | |
131 | ||
3ccc9372 MT |
132 | for (vb->num_pfns = 0; vb->num_pfns < num; |
133 | vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) { | |
61fb06cc BS |
134 | struct page *page = alloc_page(GFP_HIGHUSER | __GFP_NORETRY | |
135 | __GFP_NOMEMALLOC | __GFP_NOWARN); | |
6b35e407 RR |
136 | if (!page) { |
137 | if (printk_ratelimit()) | |
138 | dev_printk(KERN_INFO, &vb->vdev->dev, | |
139 | "Out of puff! Can't get %zu pages\n", | |
140 | num); | |
141 | /* Sleep for at least 1/5 of a second before retry. */ | |
142 | msleep(200); | |
143 | break; | |
144 | } | |
3ccc9372 MT |
145 | set_page_pfns(vb->pfns + vb->num_pfns, page); |
146 | vb->num_pages += VIRTIO_BALLOON_PAGES_PER_PAGE; | |
6b35e407 | 147 | totalram_pages--; |
6b35e407 RR |
148 | list_add(&page->lru, &vb->pages); |
149 | } | |
150 | ||
151 | /* Didn't get any? Oh well. */ | |
152 | if (vb->num_pfns == 0) | |
153 | return; | |
154 | ||
155 | tell_host(vb, vb->inflate_vq); | |
156 | } | |
157 | ||
158 | static void release_pages_by_pfn(const u32 pfns[], unsigned int num) | |
159 | { | |
160 | unsigned int i; | |
161 | ||
3ccc9372 MT |
162 | /* Find pfns pointing at start of each page, get pages and free them. */ |
163 | for (i = 0; i < num; i += VIRTIO_BALLOON_PAGES_PER_PAGE) { | |
164 | __free_page(balloon_pfn_to_page(pfns[i])); | |
6b35e407 RR |
165 | totalram_pages++; |
166 | } | |
167 | } | |
168 | ||
169 | static void leak_balloon(struct virtio_balloon *vb, size_t num) | |
170 | { | |
171 | struct page *page; | |
172 | ||
173 | /* We can only do one array worth at a time. */ | |
174 | num = min(num, ARRAY_SIZE(vb->pfns)); | |
175 | ||
3ccc9372 MT |
176 | for (vb->num_pfns = 0; vb->num_pfns < num; |
177 | vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) { | |
6b35e407 RR |
178 | page = list_first_entry(&vb->pages, struct page, lru); |
179 | list_del(&page->lru); | |
3ccc9372 MT |
180 | set_page_pfns(vb->pfns + vb->num_pfns, page); |
181 | vb->num_pages -= VIRTIO_BALLOON_PAGES_PER_PAGE; | |
6b35e407 RR |
182 | } |
183 | ||
bf50e69f DH |
184 | /* |
185 | * Note that if | |
186 | * virtio_has_feature(vdev, VIRTIO_BALLOON_F_MUST_TELL_HOST); | |
187 | * is true, we *have* to do it in this order | |
188 | */ | |
189 | tell_host(vb, vb->deflate_vq); | |
190 | release_pages_by_pfn(vb->pfns, vb->num_pfns); | |
6b35e407 RR |
191 | } |
192 | ||
9564e138 AL |
193 | static inline void update_stat(struct virtio_balloon *vb, int idx, |
194 | u16 tag, u64 val) | |
195 | { | |
196 | BUG_ON(idx >= VIRTIO_BALLOON_S_NR); | |
197 | vb->stats[idx].tag = tag; | |
198 | vb->stats[idx].val = val; | |
199 | } | |
200 | ||
201 | #define pages_to_bytes(x) ((u64)(x) << PAGE_SHIFT) | |
202 | ||
203 | static void update_balloon_stats(struct virtio_balloon *vb) | |
204 | { | |
205 | unsigned long events[NR_VM_EVENT_ITEMS]; | |
206 | struct sysinfo i; | |
207 | int idx = 0; | |
208 | ||
209 | all_vm_events(events); | |
210 | si_meminfo(&i); | |
211 | ||
212 | update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_IN, | |
213 | pages_to_bytes(events[PSWPIN])); | |
214 | update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_OUT, | |
215 | pages_to_bytes(events[PSWPOUT])); | |
216 | update_stat(vb, idx++, VIRTIO_BALLOON_S_MAJFLT, events[PGMAJFAULT]); | |
217 | update_stat(vb, idx++, VIRTIO_BALLOON_S_MINFLT, events[PGFAULT]); | |
218 | update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMFREE, | |
219 | pages_to_bytes(i.freeram)); | |
220 | update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMTOT, | |
221 | pages_to_bytes(i.totalram)); | |
222 | } | |
223 | ||
224 | /* | |
225 | * While most virtqueues communicate guest-initiated requests to the hypervisor, | |
226 | * the stats queue operates in reverse. The driver initializes the virtqueue | |
227 | * with a single buffer. From that point forward, all conversations consist of | |
228 | * a hypervisor request (a call to this function) which directs us to refill | |
1f34c71a AL |
229 | * the virtqueue with a fresh stats buffer. Since stats collection can sleep, |
230 | * we notify our kthread which does the actual work via stats_handle_request(). | |
9564e138 | 231 | */ |
1f34c71a | 232 | static void stats_request(struct virtqueue *vq) |
9564e138 AL |
233 | { |
234 | struct virtio_balloon *vb; | |
235 | unsigned int len; | |
9564e138 | 236 | |
946cfe0e | 237 | vb = virtqueue_get_buf(vq, &len); |
9564e138 AL |
238 | if (!vb) |
239 | return; | |
1f34c71a AL |
240 | vb->need_stats_update = 1; |
241 | wake_up(&vb->config_change); | |
242 | } | |
243 | ||
244 | static void stats_handle_request(struct virtio_balloon *vb) | |
245 | { | |
246 | struct virtqueue *vq; | |
247 | struct scatterlist sg; | |
9564e138 | 248 | |
1f34c71a | 249 | vb->need_stats_update = 0; |
9564e138 AL |
250 | update_balloon_stats(vb); |
251 | ||
1f34c71a | 252 | vq = vb->stats_vq; |
9564e138 | 253 | sg_init_one(&sg, vb->stats, sizeof(vb->stats)); |
f96fde41 | 254 | if (virtqueue_add_buf(vq, &sg, 1, 0, vb, GFP_KERNEL) < 0) |
9564e138 | 255 | BUG(); |
946cfe0e | 256 | virtqueue_kick(vq); |
9564e138 AL |
257 | } |
258 | ||
6b35e407 RR |
259 | static void virtballoon_changed(struct virtio_device *vdev) |
260 | { | |
261 | struct virtio_balloon *vb = vdev->priv; | |
262 | ||
263 | wake_up(&vb->config_change); | |
264 | } | |
265 | ||
bdc1681c | 266 | static inline s64 towards_target(struct virtio_balloon *vb) |
6b35e407 | 267 | { |
1a87228f DG |
268 | __le32 v; |
269 | s64 target; | |
270 | ||
72e61eb4 RR |
271 | vb->vdev->config->get(vb->vdev, |
272 | offsetof(struct virtio_balloon_config, num_pages), | |
273 | &v, sizeof(v)); | |
1a87228f DG |
274 | target = le32_to_cpu(v); |
275 | return target - vb->num_pages; | |
6b35e407 RR |
276 | } |
277 | ||
278 | static void update_balloon_size(struct virtio_balloon *vb) | |
279 | { | |
280 | __le32 actual = cpu_to_le32(vb->num_pages); | |
281 | ||
282 | vb->vdev->config->set(vb->vdev, | |
283 | offsetof(struct virtio_balloon_config, actual), | |
284 | &actual, sizeof(actual)); | |
285 | } | |
286 | ||
287 | static int balloon(void *_vballoon) | |
288 | { | |
289 | struct virtio_balloon *vb = _vballoon; | |
290 | ||
291 | set_freezable(); | |
292 | while (!kthread_should_stop()) { | |
bdc1681c | 293 | s64 diff; |
6b35e407 RR |
294 | |
295 | try_to_freeze(); | |
296 | wait_event_interruptible(vb->config_change, | |
297 | (diff = towards_target(vb)) != 0 | |
1f34c71a | 298 | || vb->need_stats_update |
84a139a9 MT |
299 | || kthread_should_stop() |
300 | || freezing(current)); | |
1f34c71a AL |
301 | if (vb->need_stats_update) |
302 | stats_handle_request(vb); | |
6b35e407 RR |
303 | if (diff > 0) |
304 | fill_balloon(vb, diff); | |
305 | else if (diff < 0) | |
306 | leak_balloon(vb, -diff); | |
307 | update_balloon_size(vb); | |
308 | } | |
309 | return 0; | |
310 | } | |
311 | ||
be91c33d | 312 | static int init_vqs(struct virtio_balloon *vb) |
6b35e407 | 313 | { |
9564e138 | 314 | struct virtqueue *vqs[3]; |
1f34c71a | 315 | vq_callback_t *callbacks[] = { balloon_ack, balloon_ack, stats_request }; |
9564e138 AL |
316 | const char *names[] = { "inflate", "deflate", "stats" }; |
317 | int err, nvqs; | |
6b35e407 | 318 | |
be91c33d AS |
319 | /* |
320 | * We expect two virtqueues: inflate and deflate, and | |
321 | * optionally stat. | |
322 | */ | |
9564e138 | 323 | nvqs = virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ) ? 3 : 2; |
be91c33d | 324 | err = vb->vdev->config->find_vqs(vb->vdev, nvqs, vqs, callbacks, names); |
d2a7ddda | 325 | if (err) |
be91c33d | 326 | return err; |
6b35e407 | 327 | |
d2a7ddda MT |
328 | vb->inflate_vq = vqs[0]; |
329 | vb->deflate_vq = vqs[1]; | |
9564e138 AL |
330 | if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) { |
331 | struct scatterlist sg; | |
332 | vb->stats_vq = vqs[2]; | |
333 | ||
334 | /* | |
335 | * Prime this virtqueue with one buffer so the hypervisor can | |
336 | * use it to signal us later. | |
337 | */ | |
338 | sg_init_one(&sg, vb->stats, sizeof vb->stats); | |
f96fde41 RR |
339 | if (virtqueue_add_buf(vb->stats_vq, &sg, 1, 0, vb, GFP_KERNEL) |
340 | < 0) | |
9564e138 | 341 | BUG(); |
946cfe0e | 342 | virtqueue_kick(vb->stats_vq); |
9564e138 | 343 | } |
be91c33d AS |
344 | return 0; |
345 | } | |
346 | ||
347 | static int virtballoon_probe(struct virtio_device *vdev) | |
348 | { | |
349 | struct virtio_balloon *vb; | |
350 | int err; | |
351 | ||
352 | vdev->priv = vb = kmalloc(sizeof(*vb), GFP_KERNEL); | |
353 | if (!vb) { | |
354 | err = -ENOMEM; | |
355 | goto out; | |
356 | } | |
357 | ||
358 | INIT_LIST_HEAD(&vb->pages); | |
359 | vb->num_pages = 0; | |
360 | init_waitqueue_head(&vb->config_change); | |
361 | vb->vdev = vdev; | |
362 | vb->need_stats_update = 0; | |
363 | ||
364 | err = init_vqs(vb); | |
365 | if (err) | |
366 | goto out_free_vb; | |
6b35e407 RR |
367 | |
368 | vb->thread = kthread_run(balloon, vb, "vballoon"); | |
369 | if (IS_ERR(vb->thread)) { | |
370 | err = PTR_ERR(vb->thread); | |
d2a7ddda | 371 | goto out_del_vqs; |
6b35e407 RR |
372 | } |
373 | ||
6b35e407 RR |
374 | return 0; |
375 | ||
d2a7ddda MT |
376 | out_del_vqs: |
377 | vdev->config->del_vqs(vdev); | |
6b35e407 RR |
378 | out_free_vb: |
379 | kfree(vb); | |
380 | out: | |
381 | return err; | |
382 | } | |
383 | ||
1e65175c | 384 | static void __devexit virtballoon_remove(struct virtio_device *vdev) |
6b35e407 RR |
385 | { |
386 | struct virtio_balloon *vb = vdev->priv; | |
387 | ||
388 | kthread_stop(vb->thread); | |
389 | ||
390 | /* There might be pages left in the balloon: free them. */ | |
391 | while (vb->num_pages) | |
392 | leak_balloon(vb, vb->num_pages); | |
b8ae0eb3 | 393 | update_balloon_size(vb); |
6b35e407 RR |
394 | |
395 | /* Now we reset the device so we can clean up the queues. */ | |
396 | vdev->config->reset(vdev); | |
397 | ||
d2a7ddda | 398 | vdev->config->del_vqs(vdev); |
6b35e407 RR |
399 | kfree(vb); |
400 | } | |
401 | ||
e562966d AS |
402 | #ifdef CONFIG_PM |
403 | static int virtballoon_freeze(struct virtio_device *vdev) | |
404 | { | |
4eb05d56 AS |
405 | struct virtio_balloon *vb = vdev->priv; |
406 | ||
e562966d AS |
407 | /* |
408 | * The kthread is already frozen by the PM core before this | |
409 | * function is called. | |
410 | */ | |
411 | ||
4eb05d56 AS |
412 | while (vb->num_pages) |
413 | leak_balloon(vb, vb->num_pages); | |
414 | update_balloon_size(vb); | |
415 | ||
e562966d AS |
416 | /* Ensure we don't get any more requests from the host */ |
417 | vdev->config->reset(vdev); | |
418 | vdev->config->del_vqs(vdev); | |
419 | return 0; | |
420 | } | |
421 | ||
4eb05d56 AS |
422 | static int restore_common(struct virtio_device *vdev) |
423 | { | |
424 | struct virtio_balloon *vb = vdev->priv; | |
425 | int ret; | |
426 | ||
427 | ret = init_vqs(vdev->priv); | |
428 | if (ret) | |
429 | return ret; | |
430 | ||
431 | fill_balloon(vb, towards_target(vb)); | |
432 | update_balloon_size(vb); | |
433 | return 0; | |
434 | } | |
435 | ||
e562966d AS |
436 | static int virtballoon_restore(struct virtio_device *vdev) |
437 | { | |
4eb05d56 | 438 | return restore_common(vdev); |
e562966d AS |
439 | } |
440 | #endif | |
441 | ||
9564e138 AL |
442 | static unsigned int features[] = { |
443 | VIRTIO_BALLOON_F_MUST_TELL_HOST, | |
444 | VIRTIO_BALLOON_F_STATS_VQ, | |
445 | }; | |
c45a6816 | 446 | |
d817cd52 | 447 | static struct virtio_driver virtio_balloon_driver = { |
c45a6816 RR |
448 | .feature_table = features, |
449 | .feature_table_size = ARRAY_SIZE(features), | |
6b35e407 RR |
450 | .driver.name = KBUILD_MODNAME, |
451 | .driver.owner = THIS_MODULE, | |
452 | .id_table = id_table, | |
453 | .probe = virtballoon_probe, | |
454 | .remove = __devexit_p(virtballoon_remove), | |
455 | .config_changed = virtballoon_changed, | |
e562966d AS |
456 | #ifdef CONFIG_PM |
457 | .freeze = virtballoon_freeze, | |
458 | .restore = virtballoon_restore, | |
e562966d | 459 | #endif |
6b35e407 RR |
460 | }; |
461 | ||
462 | static int __init init(void) | |
463 | { | |
d817cd52 | 464 | return register_virtio_driver(&virtio_balloon_driver); |
6b35e407 RR |
465 | } |
466 | ||
467 | static void __exit fini(void) | |
468 | { | |
d817cd52 | 469 | unregister_virtio_driver(&virtio_balloon_driver); |
6b35e407 RR |
470 | } |
471 | module_init(init); | |
472 | module_exit(fini); | |
473 | ||
474 | MODULE_DEVICE_TABLE(virtio, id_table); | |
475 | MODULE_DESCRIPTION("Virtio balloon driver"); | |
476 | MODULE_LICENSE("GPL"); |