blob: 05f0a80818a2b1c202e2d5104ced13b9802287d0 [file] [log] [blame]
Sasha Levin1e214a52011-11-03 10:20:04 +02001/*
2 * Virtio balloon implementation, inspired by Dor Laor and Marcelo
Rusty Russell6b35e402008-02-04 23:50:12 -05003 * 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 */
Sasha Levin1e214a52011-11-03 10:20:04 +020021
Rusty Russell6b35e402008-02-04 23:50:12 -050022#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>
Johann Felix Soden6659a0f2008-02-06 01:40:22 -080027#include <linux/delay.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090028#include <linux/slab.h>
Paul Gortmakerb5a2c4f2011-07-03 16:20:30 -040029#include <linux/module.h>
Rusty Russell6b35e402008-02-04 23:50:12 -050030
31struct virtio_balloon
32{
33 struct virtio_device *vdev;
Adam Litke9564e132009-11-30 10:14:15 -060034 struct virtqueue *inflate_vq, *deflate_vq, *stats_vq;
Rusty Russell6b35e402008-02-04 23:50:12 -050035
36 /* Where the ballooning thread waits for config to change. */
37 wait_queue_head_t config_change;
38
39 /* The thread servicing the balloon. */
40 struct task_struct *thread;
41
42 /* Waiting for host to ack the pages we released. */
43 struct completion acked;
44
Rusty Russell6b35e402008-02-04 23:50:12 -050045 /* The pages we've told the Host we're not using. */
46 unsigned int num_pages;
47 struct list_head pages;
48
49 /* The array of pfns we tell the Host about. */
50 unsigned int num_pfns;
51 u32 pfns[256];
Adam Litke9564e132009-11-30 10:14:15 -060052
53 /* Memory statistics */
Adam Litke1f34c712009-12-10 16:35:15 -060054 int need_stats_update;
Adam Litke9564e132009-11-30 10:14:15 -060055 struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR];
Rusty Russell6b35e402008-02-04 23:50:12 -050056};
57
58static struct virtio_device_id id_table[] = {
59 { VIRTIO_ID_BALLOON, VIRTIO_DEV_ANY_ID },
60 { 0 },
61};
62
Hollis Blanchard1b4aa2f2008-11-13 15:48:33 -060063static u32 page_to_balloon_pfn(struct page *page)
64{
65 unsigned long pfn = page_to_pfn(page);
66
67 BUILD_BUG_ON(PAGE_SHIFT < VIRTIO_BALLOON_PFN_SHIFT);
68 /* Convert pfn from Linux page size to balloon page size. */
69 return pfn >> (PAGE_SHIFT - VIRTIO_BALLOON_PFN_SHIFT);
70}
71
Rusty Russell6b35e402008-02-04 23:50:12 -050072static void balloon_ack(struct virtqueue *vq)
73{
74 struct virtio_balloon *vb;
75 unsigned int len;
76
Michael S. Tsirkin946cfe02010-04-12 16:18:28 +030077 vb = virtqueue_get_buf(vq, &len);
Rusty Russell6b35e402008-02-04 23:50:12 -050078 if (vb)
79 complete(&vb->acked);
80}
81
82static void tell_host(struct virtio_balloon *vb, struct virtqueue *vq)
83{
84 struct scatterlist sg;
85
86 sg_init_one(&sg, vb->pfns, sizeof(vb->pfns[0]) * vb->num_pfns);
87
88 init_completion(&vb->acked);
89
90 /* We should always be able to add one buffer to an empty queue. */
Rusty Russellf96fde42012-01-12 15:44:42 +103091 if (virtqueue_add_buf(vq, &sg, 1, 0, vb, GFP_KERNEL) < 0)
Rusty Russell6b35e402008-02-04 23:50:12 -050092 BUG();
Michael S. Tsirkin946cfe02010-04-12 16:18:28 +030093 virtqueue_kick(vq);
Rusty Russell6b35e402008-02-04 23:50:12 -050094
95 /* When host has read buffer, this completes via balloon_ack */
96 wait_for_completion(&vb->acked);
97}
98
99static void fill_balloon(struct virtio_balloon *vb, size_t num)
100{
101 /* We can only do one array worth at a time. */
102 num = min(num, ARRAY_SIZE(vb->pfns));
103
104 for (vb->num_pfns = 0; vb->num_pfns < num; vb->num_pfns++) {
Balbir Singh61fb06c2010-04-22 12:22:34 +0930105 struct page *page = alloc_page(GFP_HIGHUSER | __GFP_NORETRY |
106 __GFP_NOMEMALLOC | __GFP_NOWARN);
Rusty Russell6b35e402008-02-04 23:50:12 -0500107 if (!page) {
108 if (printk_ratelimit())
109 dev_printk(KERN_INFO, &vb->vdev->dev,
110 "Out of puff! Can't get %zu pages\n",
111 num);
112 /* Sleep for at least 1/5 of a second before retry. */
113 msleep(200);
114 break;
115 }
Hollis Blanchard1b4aa2f2008-11-13 15:48:33 -0600116 vb->pfns[vb->num_pfns] = page_to_balloon_pfn(page);
Rusty Russell6b35e402008-02-04 23:50:12 -0500117 totalram_pages--;
118 vb->num_pages++;
119 list_add(&page->lru, &vb->pages);
120 }
121
122 /* Didn't get any? Oh well. */
123 if (vb->num_pfns == 0)
124 return;
125
126 tell_host(vb, vb->inflate_vq);
127}
128
129static void release_pages_by_pfn(const u32 pfns[], unsigned int num)
130{
131 unsigned int i;
132
133 for (i = 0; i < num; i++) {
134 __free_page(pfn_to_page(pfns[i]));
135 totalram_pages++;
136 }
137}
138
139static void leak_balloon(struct virtio_balloon *vb, size_t num)
140{
141 struct page *page;
142
143 /* We can only do one array worth at a time. */
144 num = min(num, ARRAY_SIZE(vb->pfns));
145
146 for (vb->num_pfns = 0; vb->num_pfns < num; vb->num_pfns++) {
147 page = list_first_entry(&vb->pages, struct page, lru);
148 list_del(&page->lru);
Hollis Blanchard1b4aa2f2008-11-13 15:48:33 -0600149 vb->pfns[vb->num_pfns] = page_to_balloon_pfn(page);
Rusty Russell6b35e402008-02-04 23:50:12 -0500150 vb->num_pages--;
151 }
152
Dave Hansenbf50e692011-04-07 10:43:25 -0700153 /*
154 * Note that if
155 * virtio_has_feature(vdev, VIRTIO_BALLOON_F_MUST_TELL_HOST);
156 * is true, we *have* to do it in this order
157 */
158 tell_host(vb, vb->deflate_vq);
159 release_pages_by_pfn(vb->pfns, vb->num_pfns);
Rusty Russell6b35e402008-02-04 23:50:12 -0500160}
161
Adam Litke9564e132009-11-30 10:14:15 -0600162static inline void update_stat(struct virtio_balloon *vb, int idx,
163 u16 tag, u64 val)
164{
165 BUG_ON(idx >= VIRTIO_BALLOON_S_NR);
166 vb->stats[idx].tag = tag;
167 vb->stats[idx].val = val;
168}
169
170#define pages_to_bytes(x) ((u64)(x) << PAGE_SHIFT)
171
172static void update_balloon_stats(struct virtio_balloon *vb)
173{
174 unsigned long events[NR_VM_EVENT_ITEMS];
175 struct sysinfo i;
176 int idx = 0;
177
178 all_vm_events(events);
179 si_meminfo(&i);
180
181 update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_IN,
182 pages_to_bytes(events[PSWPIN]));
183 update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_OUT,
184 pages_to_bytes(events[PSWPOUT]));
185 update_stat(vb, idx++, VIRTIO_BALLOON_S_MAJFLT, events[PGMAJFAULT]);
186 update_stat(vb, idx++, VIRTIO_BALLOON_S_MINFLT, events[PGFAULT]);
187 update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMFREE,
188 pages_to_bytes(i.freeram));
189 update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMTOT,
190 pages_to_bytes(i.totalram));
191}
192
193/*
194 * While most virtqueues communicate guest-initiated requests to the hypervisor,
195 * the stats queue operates in reverse. The driver initializes the virtqueue
196 * with a single buffer. From that point forward, all conversations consist of
197 * a hypervisor request (a call to this function) which directs us to refill
Adam Litke1f34c712009-12-10 16:35:15 -0600198 * the virtqueue with a fresh stats buffer. Since stats collection can sleep,
199 * we notify our kthread which does the actual work via stats_handle_request().
Adam Litke9564e132009-11-30 10:14:15 -0600200 */
Adam Litke1f34c712009-12-10 16:35:15 -0600201static void stats_request(struct virtqueue *vq)
Adam Litke9564e132009-11-30 10:14:15 -0600202{
203 struct virtio_balloon *vb;
204 unsigned int len;
Adam Litke9564e132009-11-30 10:14:15 -0600205
Michael S. Tsirkin946cfe02010-04-12 16:18:28 +0300206 vb = virtqueue_get_buf(vq, &len);
Adam Litke9564e132009-11-30 10:14:15 -0600207 if (!vb)
208 return;
Adam Litke1f34c712009-12-10 16:35:15 -0600209 vb->need_stats_update = 1;
210 wake_up(&vb->config_change);
211}
Adam Litke9564e132009-11-30 10:14:15 -0600212
Adam Litke1f34c712009-12-10 16:35:15 -0600213static void stats_handle_request(struct virtio_balloon *vb)
214{
215 struct virtqueue *vq;
216 struct scatterlist sg;
217
218 vb->need_stats_update = 0;
Adam Litke9564e132009-11-30 10:14:15 -0600219 update_balloon_stats(vb);
220
Adam Litke1f34c712009-12-10 16:35:15 -0600221 vq = vb->stats_vq;
Adam Litke9564e132009-11-30 10:14:15 -0600222 sg_init_one(&sg, vb->stats, sizeof(vb->stats));
Rusty Russellf96fde42012-01-12 15:44:42 +1030223 if (virtqueue_add_buf(vq, &sg, 1, 0, vb, GFP_KERNEL) < 0)
Adam Litke9564e132009-11-30 10:14:15 -0600224 BUG();
Michael S. Tsirkin946cfe02010-04-12 16:18:28 +0300225 virtqueue_kick(vq);
Adam Litke9564e132009-11-30 10:14:15 -0600226}
227
Rusty Russell6b35e402008-02-04 23:50:12 -0500228static void virtballoon_changed(struct virtio_device *vdev)
229{
230 struct virtio_balloon *vb = vdev->priv;
231
232 wake_up(&vb->config_change);
233}
234
Rusty Russellbdc16812008-03-17 22:58:15 -0500235static inline s64 towards_target(struct virtio_balloon *vb)
Rusty Russell6b35e402008-02-04 23:50:12 -0500236{
237 u32 v;
Rusty Russell72e61eb2008-05-02 21:50:49 -0500238 vb->vdev->config->get(vb->vdev,
239 offsetof(struct virtio_balloon_config, num_pages),
240 &v, sizeof(v));
Anthony Liguori532a6082008-08-18 17:15:31 -0500241 return (s64)v - vb->num_pages;
Rusty Russell6b35e402008-02-04 23:50:12 -0500242}
243
244static void update_balloon_size(struct virtio_balloon *vb)
245{
246 __le32 actual = cpu_to_le32(vb->num_pages);
247
248 vb->vdev->config->set(vb->vdev,
249 offsetof(struct virtio_balloon_config, actual),
250 &actual, sizeof(actual));
251}
252
253static int balloon(void *_vballoon)
254{
255 struct virtio_balloon *vb = _vballoon;
256
257 set_freezable();
258 while (!kthread_should_stop()) {
Rusty Russellbdc16812008-03-17 22:58:15 -0500259 s64 diff;
Rusty Russell6b35e402008-02-04 23:50:12 -0500260
261 try_to_freeze();
262 wait_event_interruptible(vb->config_change,
263 (diff = towards_target(vb)) != 0
Adam Litke1f34c712009-12-10 16:35:15 -0600264 || vb->need_stats_update
Marcelo Tosatti84a139a2009-04-16 21:14:04 -0300265 || kthread_should_stop()
266 || freezing(current));
Adam Litke1f34c712009-12-10 16:35:15 -0600267 if (vb->need_stats_update)
268 stats_handle_request(vb);
Rusty Russell6b35e402008-02-04 23:50:12 -0500269 if (diff > 0)
270 fill_balloon(vb, diff);
271 else if (diff < 0)
272 leak_balloon(vb, -diff);
273 update_balloon_size(vb);
274 }
275 return 0;
276}
277
Amit Shahbe91c332011-12-22 16:58:34 +0530278static int init_vqs(struct virtio_balloon *vb)
Rusty Russell6b35e402008-02-04 23:50:12 -0500279{
Adam Litke9564e132009-11-30 10:14:15 -0600280 struct virtqueue *vqs[3];
Adam Litke1f34c712009-12-10 16:35:15 -0600281 vq_callback_t *callbacks[] = { balloon_ack, balloon_ack, stats_request };
Adam Litke9564e132009-11-30 10:14:15 -0600282 const char *names[] = { "inflate", "deflate", "stats" };
283 int err, nvqs;
Rusty Russell6b35e402008-02-04 23:50:12 -0500284
Amit Shahbe91c332011-12-22 16:58:34 +0530285 /*
286 * We expect two virtqueues: inflate and deflate, and
287 * optionally stat.
288 */
Adam Litke9564e132009-11-30 10:14:15 -0600289 nvqs = virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ) ? 3 : 2;
Amit Shahbe91c332011-12-22 16:58:34 +0530290 err = vb->vdev->config->find_vqs(vb->vdev, nvqs, vqs, callbacks, names);
Michael S. Tsirkind2a7ddd2009-06-12 22:16:36 -0600291 if (err)
Amit Shahbe91c332011-12-22 16:58:34 +0530292 return err;
Rusty Russell6b35e402008-02-04 23:50:12 -0500293
Michael S. Tsirkind2a7ddd2009-06-12 22:16:36 -0600294 vb->inflate_vq = vqs[0];
295 vb->deflate_vq = vqs[1];
Adam Litke9564e132009-11-30 10:14:15 -0600296 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {
297 struct scatterlist sg;
298 vb->stats_vq = vqs[2];
299
300 /*
301 * Prime this virtqueue with one buffer so the hypervisor can
302 * use it to signal us later.
303 */
304 sg_init_one(&sg, vb->stats, sizeof vb->stats);
Rusty Russellf96fde42012-01-12 15:44:42 +1030305 if (virtqueue_add_buf(vb->stats_vq, &sg, 1, 0, vb, GFP_KERNEL)
306 < 0)
Adam Litke9564e132009-11-30 10:14:15 -0600307 BUG();
Michael S. Tsirkin946cfe02010-04-12 16:18:28 +0300308 virtqueue_kick(vb->stats_vq);
Adam Litke9564e132009-11-30 10:14:15 -0600309 }
Amit Shahbe91c332011-12-22 16:58:34 +0530310 return 0;
311}
312
313static int virtballoon_probe(struct virtio_device *vdev)
314{
315 struct virtio_balloon *vb;
316 int err;
317
318 vdev->priv = vb = kmalloc(sizeof(*vb), GFP_KERNEL);
319 if (!vb) {
320 err = -ENOMEM;
321 goto out;
322 }
323
324 INIT_LIST_HEAD(&vb->pages);
325 vb->num_pages = 0;
326 init_waitqueue_head(&vb->config_change);
327 vb->vdev = vdev;
328 vb->need_stats_update = 0;
329
330 err = init_vqs(vb);
331 if (err)
332 goto out_free_vb;
Rusty Russell6b35e402008-02-04 23:50:12 -0500333
334 vb->thread = kthread_run(balloon, vb, "vballoon");
335 if (IS_ERR(vb->thread)) {
336 err = PTR_ERR(vb->thread);
Michael S. Tsirkind2a7ddd2009-06-12 22:16:36 -0600337 goto out_del_vqs;
Rusty Russell6b35e402008-02-04 23:50:12 -0500338 }
339
Rusty Russell6b35e402008-02-04 23:50:12 -0500340 return 0;
341
Michael S. Tsirkind2a7ddd2009-06-12 22:16:36 -0600342out_del_vqs:
343 vdev->config->del_vqs(vdev);
Rusty Russell6b35e402008-02-04 23:50:12 -0500344out_free_vb:
345 kfree(vb);
346out:
347 return err;
348}
349
Uwe Kleine-König1e651752009-10-01 10:28:33 +0200350static void __devexit virtballoon_remove(struct virtio_device *vdev)
Rusty Russell6b35e402008-02-04 23:50:12 -0500351{
352 struct virtio_balloon *vb = vdev->priv;
353
354 kthread_stop(vb->thread);
355
356 /* There might be pages left in the balloon: free them. */
357 while (vb->num_pages)
358 leak_balloon(vb, vb->num_pages);
359
360 /* Now we reset the device so we can clean up the queues. */
361 vdev->config->reset(vdev);
362
Michael S. Tsirkind2a7ddd2009-06-12 22:16:36 -0600363 vdev->config->del_vqs(vdev);
Rusty Russell6b35e402008-02-04 23:50:12 -0500364 kfree(vb);
365}
366
Amit Shahe5629662011-12-22 16:58:35 +0530367#ifdef CONFIG_PM
368static int virtballoon_freeze(struct virtio_device *vdev)
369{
Amit Shah4eb05d52012-02-29 17:42:51 +0530370 struct virtio_balloon *vb = vdev->priv;
371
Amit Shahe5629662011-12-22 16:58:35 +0530372 /*
373 * The kthread is already frozen by the PM core before this
374 * function is called.
375 */
376
Amit Shah4eb05d52012-02-29 17:42:51 +0530377 while (vb->num_pages)
378 leak_balloon(vb, vb->num_pages);
379 update_balloon_size(vb);
380
Amit Shahe5629662011-12-22 16:58:35 +0530381 /* Ensure we don't get any more requests from the host */
382 vdev->config->reset(vdev);
383 vdev->config->del_vqs(vdev);
384 return 0;
385}
386
Amit Shah4eb05d52012-02-29 17:42:51 +0530387static int restore_common(struct virtio_device *vdev)
388{
389 struct virtio_balloon *vb = vdev->priv;
390 int ret;
391
392 ret = init_vqs(vdev->priv);
393 if (ret)
394 return ret;
395
396 fill_balloon(vb, towards_target(vb));
397 update_balloon_size(vb);
398 return 0;
399}
400
Amit Shahe5629662011-12-22 16:58:35 +0530401static int virtballoon_restore(struct virtio_device *vdev)
402{
Amit Shah4eb05d52012-02-29 17:42:51 +0530403 return restore_common(vdev);
Amit Shahe5629662011-12-22 16:58:35 +0530404}
405#endif
406
Adam Litke9564e132009-11-30 10:14:15 -0600407static unsigned int features[] = {
408 VIRTIO_BALLOON_F_MUST_TELL_HOST,
409 VIRTIO_BALLOON_F_STATS_VQ,
410};
Rusty Russellc45a6812008-05-02 21:50:50 -0500411
Jeff Mahoneyd817cd52010-01-15 17:01:26 -0800412static struct virtio_driver virtio_balloon_driver = {
Rusty Russellc45a6812008-05-02 21:50:50 -0500413 .feature_table = features,
414 .feature_table_size = ARRAY_SIZE(features),
Rusty Russell6b35e402008-02-04 23:50:12 -0500415 .driver.name = KBUILD_MODNAME,
416 .driver.owner = THIS_MODULE,
417 .id_table = id_table,
418 .probe = virtballoon_probe,
419 .remove = __devexit_p(virtballoon_remove),
420 .config_changed = virtballoon_changed,
Amit Shahe5629662011-12-22 16:58:35 +0530421#ifdef CONFIG_PM
422 .freeze = virtballoon_freeze,
423 .restore = virtballoon_restore,
Amit Shahe5629662011-12-22 16:58:35 +0530424#endif
Rusty Russell6b35e402008-02-04 23:50:12 -0500425};
426
427static int __init init(void)
428{
Jeff Mahoneyd817cd52010-01-15 17:01:26 -0800429 return register_virtio_driver(&virtio_balloon_driver);
Rusty Russell6b35e402008-02-04 23:50:12 -0500430}
431
432static void __exit fini(void)
433{
Jeff Mahoneyd817cd52010-01-15 17:01:26 -0800434 unregister_virtio_driver(&virtio_balloon_driver);
Rusty Russell6b35e402008-02-04 23:50:12 -0500435}
436module_init(init);
437module_exit(fini);
438
439MODULE_DEVICE_TABLE(virtio, id_table);
440MODULE_DESCRIPTION("Virtio balloon driver");
441MODULE_LICENSE("GPL");