blob: 50c5f42d7a9f3010c5f12275b7fd540161900392 [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>
Rafael Aquinie2250422012-12-11 16:02:45 -080030#include <linux/balloon_compaction.h>
Raushaniya Maksudova5a10b7d2014-11-10 09:36:29 +103031#include <linux/oom.h>
Rusty Russell6b35e402008-02-04 23:50:12 -050032
Michael S. Tsirkin3ccc9372012-04-12 16:38:00 +030033/*
34 * Balloon device works in 4K page units. So each page is pointed to by
35 * multiple balloon pages. All memory counters in this driver are in balloon
36 * page units.
37 */
Rafael Aquinie2250422012-12-11 16:02:45 -080038#define VIRTIO_BALLOON_PAGES_PER_PAGE (unsigned)(PAGE_SIZE >> VIRTIO_BALLOON_PFN_SHIFT)
39#define VIRTIO_BALLOON_ARRAY_PFNS_MAX 256
Raushaniya Maksudova5a10b7d2014-11-10 09:36:29 +103040#define OOM_VBALLOON_DEFAULT_PAGES 256
41#define VIRTBALLOON_OOM_NOTIFY_PRIORITY 80
42
43static int oom_pages = OOM_VBALLOON_DEFAULT_PAGES;
44module_param(oom_pages, int, S_IRUSR | S_IWUSR);
45MODULE_PARM_DESC(oom_pages, "pages to free on OOM");
Michael S. Tsirkin3ccc9372012-04-12 16:38:00 +030046
Rusty Russell6b35e402008-02-04 23:50:12 -050047struct virtio_balloon
48{
49 struct virtio_device *vdev;
Adam Litke9564e132009-11-30 10:14:15 -060050 struct virtqueue *inflate_vq, *deflate_vq, *stats_vq;
Rusty Russell6b35e402008-02-04 23:50:12 -050051
52 /* Where the ballooning thread waits for config to change. */
53 wait_queue_head_t config_change;
54
55 /* The thread servicing the balloon. */
56 struct task_struct *thread;
57
58 /* Waiting for host to ack the pages we released. */
Michael S. Tsirkin9c378ab2012-07-02 10:33:08 +030059 wait_queue_head_t acked;
Rusty Russell6b35e402008-02-04 23:50:12 -050060
Michael S. Tsirkin3ccc9372012-04-12 16:38:00 +030061 /* Number of balloon pages we've told the Host we're not using. */
Rusty Russell6b35e402008-02-04 23:50:12 -050062 unsigned int num_pages;
Michael S. Tsirkin3ccc9372012-04-12 16:38:00 +030063 /*
Rafael Aquinie2250422012-12-11 16:02:45 -080064 * The pages we've told the Host we're not using are enqueued
65 * at vb_dev_info->pages list.
Michael S. Tsirkin3ccc9372012-04-12 16:38:00 +030066 * Each page on this list adds VIRTIO_BALLOON_PAGES_PER_PAGE
67 * to num_pages above.
68 */
Konstantin Khlebnikov9d1ba802014-10-09 15:29:29 -070069 struct balloon_dev_info vb_dev_info;
Rafael Aquinie2250422012-12-11 16:02:45 -080070
71 /* Synchronize access/update to this struct virtio_balloon elements */
72 struct mutex balloon_lock;
Rusty Russell6b35e402008-02-04 23:50:12 -050073
74 /* The array of pfns we tell the Host about. */
75 unsigned int num_pfns;
Rafael Aquinie2250422012-12-11 16:02:45 -080076 u32 pfns[VIRTIO_BALLOON_ARRAY_PFNS_MAX];
Adam Litke9564e132009-11-30 10:14:15 -060077
78 /* Memory statistics */
Adam Litke1f34c712009-12-10 16:35:15 -060079 int need_stats_update;
Adam Litke9564e132009-11-30 10:14:15 -060080 struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR];
Raushaniya Maksudova5a10b7d2014-11-10 09:36:29 +103081
82 /* To register callback in oom notifier call chain */
83 struct notifier_block nb;
Rusty Russell6b35e402008-02-04 23:50:12 -050084};
85
86static struct virtio_device_id id_table[] = {
87 { VIRTIO_ID_BALLOON, VIRTIO_DEV_ANY_ID },
88 { 0 },
89};
90
Hollis Blanchard1b4aa2f2008-11-13 15:48:33 -060091static u32 page_to_balloon_pfn(struct page *page)
92{
93 unsigned long pfn = page_to_pfn(page);
94
95 BUILD_BUG_ON(PAGE_SHIFT < VIRTIO_BALLOON_PFN_SHIFT);
96 /* Convert pfn from Linux page size to balloon page size. */
Michael S. Tsirkin3ccc9372012-04-12 16:38:00 +030097 return pfn * VIRTIO_BALLOON_PAGES_PER_PAGE;
98}
99
100static struct page *balloon_pfn_to_page(u32 pfn)
101{
102 BUG_ON(pfn % VIRTIO_BALLOON_PAGES_PER_PAGE);
103 return pfn_to_page(pfn / VIRTIO_BALLOON_PAGES_PER_PAGE);
Hollis Blanchard1b4aa2f2008-11-13 15:48:33 -0600104}
105
Rusty Russell6b35e402008-02-04 23:50:12 -0500106static void balloon_ack(struct virtqueue *vq)
107{
Michael S. Tsirkin9c378ab2012-07-02 10:33:08 +0300108 struct virtio_balloon *vb = vq->vdev->priv;
Rusty Russell6b35e402008-02-04 23:50:12 -0500109
Michael S. Tsirkin9c378ab2012-07-02 10:33:08 +0300110 wake_up(&vb->acked);
Rusty Russell6b35e402008-02-04 23:50:12 -0500111}
112
113static void tell_host(struct virtio_balloon *vb, struct virtqueue *vq)
114{
115 struct scatterlist sg;
Michael S. Tsirkin9c378ab2012-07-02 10:33:08 +0300116 unsigned int len;
Rusty Russell6b35e402008-02-04 23:50:12 -0500117
118 sg_init_one(&sg, vb->pfns, sizeof(vb->pfns[0]) * vb->num_pfns);
119
Rusty Russell6b35e402008-02-04 23:50:12 -0500120 /* We should always be able to add one buffer to an empty queue. */
Rusty Russell4951cc92014-03-13 11:23:40 +1030121 virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL);
Michael S. Tsirkin946cfe02010-04-12 16:18:28 +0300122 virtqueue_kick(vq);
Rusty Russell6b35e402008-02-04 23:50:12 -0500123
124 /* When host has read buffer, this completes via balloon_ack */
Michael S. Tsirkin9c378ab2012-07-02 10:33:08 +0300125 wait_event(vb->acked, virtqueue_get_buf(vq, &len));
Rusty Russell6b35e402008-02-04 23:50:12 -0500126}
127
Michael S. Tsirkin3ccc9372012-04-12 16:38:00 +0300128static void set_page_pfns(u32 pfns[], struct page *page)
129{
130 unsigned int i;
131
132 /* Set balloon pfns pointing at this page.
133 * Note that the first pfn points at start of the page. */
134 for (i = 0; i < VIRTIO_BALLOON_PAGES_PER_PAGE; i++)
135 pfns[i] = page_to_balloon_pfn(page) + i;
136}
137
Rusty Russell6b35e402008-02-04 23:50:12 -0500138static void fill_balloon(struct virtio_balloon *vb, size_t num)
139{
Konstantin Khlebnikov9d1ba802014-10-09 15:29:29 -0700140 struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info;
Rafael Aquinie2250422012-12-11 16:02:45 -0800141
Rusty Russell6b35e402008-02-04 23:50:12 -0500142 /* We can only do one array worth at a time. */
143 num = min(num, ARRAY_SIZE(vb->pfns));
144
Rafael Aquinie2250422012-12-11 16:02:45 -0800145 mutex_lock(&vb->balloon_lock);
Michael S. Tsirkin3ccc9372012-04-12 16:38:00 +0300146 for (vb->num_pfns = 0; vb->num_pfns < num;
147 vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) {
Rafael Aquinie2250422012-12-11 16:02:45 -0800148 struct page *page = balloon_page_enqueue(vb_dev_info);
149
Rusty Russell6b35e402008-02-04 23:50:12 -0500150 if (!page) {
Joe Perches800ba5e2012-10-31 09:27:22 +1030151 dev_info_ratelimited(&vb->vdev->dev,
Linus Torvaldsb7dfde92012-12-20 08:37:04 -0800152 "Out of puff! Can't get %u pages\n",
153 VIRTIO_BALLOON_PAGES_PER_PAGE);
Rusty Russell6b35e402008-02-04 23:50:12 -0500154 /* Sleep for at least 1/5 of a second before retry. */
155 msleep(200);
156 break;
157 }
Michael S. Tsirkin3ccc9372012-04-12 16:38:00 +0300158 set_page_pfns(vb->pfns + vb->num_pfns, page);
159 vb->num_pages += VIRTIO_BALLOON_PAGES_PER_PAGE;
Jiang Liu3dcc0572013-07-03 15:03:21 -0700160 adjust_managed_page_count(page, -1);
Rusty Russell6b35e402008-02-04 23:50:12 -0500161 }
162
Rafael Aquinie2250422012-12-11 16:02:45 -0800163 /* Did we get any? */
164 if (vb->num_pfns != 0)
165 tell_host(vb, vb->inflate_vq);
166 mutex_unlock(&vb->balloon_lock);
Rusty Russell6b35e402008-02-04 23:50:12 -0500167}
168
169static void release_pages_by_pfn(const u32 pfns[], unsigned int num)
170{
171 unsigned int i;
172
Michael S. Tsirkin3ccc9372012-04-12 16:38:00 +0300173 /* Find pfns pointing at start of each page, get pages and free them. */
174 for (i = 0; i < num; i += VIRTIO_BALLOON_PAGES_PER_PAGE) {
Jiang Liu3dcc0572013-07-03 15:03:21 -0700175 struct page *page = balloon_pfn_to_page(pfns[i]);
Jiang Liu3dcc0572013-07-03 15:03:21 -0700176 adjust_managed_page_count(page, 1);
Konstantin Khlebnikovd6d86c02014-10-09 15:29:27 -0700177 put_page(page); /* balloon reference */
Rusty Russell6b35e402008-02-04 23:50:12 -0500178 }
179}
180
Raushaniya Maksudova1fd9c672014-11-10 09:35:29 +1030181static unsigned leak_balloon(struct virtio_balloon *vb, size_t num)
Rusty Russell6b35e402008-02-04 23:50:12 -0500182{
Raushaniya Maksudova1fd9c672014-11-10 09:35:29 +1030183 unsigned num_freed_pages;
Rusty Russell6b35e402008-02-04 23:50:12 -0500184 struct page *page;
Konstantin Khlebnikov9d1ba802014-10-09 15:29:29 -0700185 struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info;
Rusty Russell6b35e402008-02-04 23:50:12 -0500186
187 /* We can only do one array worth at a time. */
188 num = min(num, ARRAY_SIZE(vb->pfns));
189
Rafael Aquinie2250422012-12-11 16:02:45 -0800190 mutex_lock(&vb->balloon_lock);
Michael S. Tsirkin3ccc9372012-04-12 16:38:00 +0300191 for (vb->num_pfns = 0; vb->num_pfns < num;
192 vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) {
Rafael Aquinie2250422012-12-11 16:02:45 -0800193 page = balloon_page_dequeue(vb_dev_info);
194 if (!page)
195 break;
Michael S. Tsirkin3ccc9372012-04-12 16:38:00 +0300196 set_page_pfns(vb->pfns + vb->num_pfns, page);
197 vb->num_pages -= VIRTIO_BALLOON_PAGES_PER_PAGE;
Rusty Russell6b35e402008-02-04 23:50:12 -0500198 }
199
Raushaniya Maksudova1fd9c672014-11-10 09:35:29 +1030200 num_freed_pages = vb->num_pfns;
Dave Hansenbf50e692011-04-07 10:43:25 -0700201 /*
202 * Note that if
203 * virtio_has_feature(vdev, VIRTIO_BALLOON_F_MUST_TELL_HOST);
204 * is true, we *have* to do it in this order
205 */
Luiz Capitulino8c6bab42013-07-02 15:35:13 +0930206 if (vb->num_pfns != 0)
207 tell_host(vb, vb->deflate_vq);
Rafael Aquinie2250422012-12-11 16:02:45 -0800208 mutex_unlock(&vb->balloon_lock);
Dave Hansenbf50e692011-04-07 10:43:25 -0700209 release_pages_by_pfn(vb->pfns, vb->num_pfns);
Raushaniya Maksudova1fd9c672014-11-10 09:35:29 +1030210 return num_freed_pages;
Rusty Russell6b35e402008-02-04 23:50:12 -0500211}
212
Adam Litke9564e132009-11-30 10:14:15 -0600213static inline void update_stat(struct virtio_balloon *vb, int idx,
214 u16 tag, u64 val)
215{
216 BUG_ON(idx >= VIRTIO_BALLOON_S_NR);
217 vb->stats[idx].tag = tag;
218 vb->stats[idx].val = val;
219}
220
221#define pages_to_bytes(x) ((u64)(x) << PAGE_SHIFT)
222
223static void update_balloon_stats(struct virtio_balloon *vb)
224{
225 unsigned long events[NR_VM_EVENT_ITEMS];
226 struct sysinfo i;
227 int idx = 0;
228
229 all_vm_events(events);
230 si_meminfo(&i);
231
232 update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_IN,
233 pages_to_bytes(events[PSWPIN]));
234 update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_OUT,
235 pages_to_bytes(events[PSWPOUT]));
236 update_stat(vb, idx++, VIRTIO_BALLOON_S_MAJFLT, events[PGMAJFAULT]);
237 update_stat(vb, idx++, VIRTIO_BALLOON_S_MINFLT, events[PGFAULT]);
238 update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMFREE,
239 pages_to_bytes(i.freeram));
240 update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMTOT,
241 pages_to_bytes(i.totalram));
242}
243
244/*
245 * While most virtqueues communicate guest-initiated requests to the hypervisor,
246 * the stats queue operates in reverse. The driver initializes the virtqueue
247 * with a single buffer. From that point forward, all conversations consist of
248 * a hypervisor request (a call to this function) which directs us to refill
Adam Litke1f34c712009-12-10 16:35:15 -0600249 * the virtqueue with a fresh stats buffer. Since stats collection can sleep,
250 * we notify our kthread which does the actual work via stats_handle_request().
Adam Litke9564e132009-11-30 10:14:15 -0600251 */
Adam Litke1f34c712009-12-10 16:35:15 -0600252static void stats_request(struct virtqueue *vq)
Adam Litke9564e132009-11-30 10:14:15 -0600253{
Michael S. Tsirkin9c378ab2012-07-02 10:33:08 +0300254 struct virtio_balloon *vb = vq->vdev->priv;
Adam Litke9564e132009-11-30 10:14:15 -0600255
Adam Litke1f34c712009-12-10 16:35:15 -0600256 vb->need_stats_update = 1;
257 wake_up(&vb->config_change);
258}
Adam Litke9564e132009-11-30 10:14:15 -0600259
Adam Litke1f34c712009-12-10 16:35:15 -0600260static void stats_handle_request(struct virtio_balloon *vb)
261{
262 struct virtqueue *vq;
263 struct scatterlist sg;
Michael S. Tsirkin9c378ab2012-07-02 10:33:08 +0300264 unsigned int len;
Adam Litke1f34c712009-12-10 16:35:15 -0600265
266 vb->need_stats_update = 0;
Adam Litke9564e132009-11-30 10:14:15 -0600267 update_balloon_stats(vb);
268
Adam Litke1f34c712009-12-10 16:35:15 -0600269 vq = vb->stats_vq;
Michael S. Tsirkin9c378ab2012-07-02 10:33:08 +0300270 if (!virtqueue_get_buf(vq, &len))
271 return;
Adam Litke9564e132009-11-30 10:14:15 -0600272 sg_init_one(&sg, vb->stats, sizeof(vb->stats));
Rusty Russell4951cc92014-03-13 11:23:40 +1030273 virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL);
Michael S. Tsirkin946cfe02010-04-12 16:18:28 +0300274 virtqueue_kick(vq);
Adam Litke9564e132009-11-30 10:14:15 -0600275}
276
Rusty Russell6b35e402008-02-04 23:50:12 -0500277static void virtballoon_changed(struct virtio_device *vdev)
278{
279 struct virtio_balloon *vb = vdev->priv;
280
281 wake_up(&vb->config_change);
282}
283
Rusty Russellbdc16812008-03-17 22:58:15 -0500284static inline s64 towards_target(struct virtio_balloon *vb)
Rusty Russell6b35e402008-02-04 23:50:12 -0500285{
David Gibson1a872282012-04-12 15:36:34 +1000286 __le32 v;
287 s64 target;
288
Rusty Russell855e0c52013-10-14 18:11:51 +1030289 virtio_cread(vb->vdev, struct virtio_balloon_config, num_pages, &v);
290
David Gibson1a872282012-04-12 15:36:34 +1000291 target = le32_to_cpu(v);
292 return target - vb->num_pages;
Rusty Russell6b35e402008-02-04 23:50:12 -0500293}
294
295static void update_balloon_size(struct virtio_balloon *vb)
296{
297 __le32 actual = cpu_to_le32(vb->num_pages);
298
Luiz Capitulino3459f112013-12-05 13:04:10 +1030299 virtio_cwrite(vb->vdev, struct virtio_balloon_config, actual,
Rusty Russell855e0c52013-10-14 18:11:51 +1030300 &actual);
Rusty Russell6b35e402008-02-04 23:50:12 -0500301}
302
Raushaniya Maksudova5a10b7d2014-11-10 09:36:29 +1030303/*
304 * virtballoon_oom_notify - release pages when system is under severe
305 * memory pressure (called from out_of_memory())
306 * @self : notifier block struct
307 * @dummy: not used
308 * @parm : returned - number of freed pages
309 *
310 * The balancing of memory by use of the virtio balloon should not cause
311 * the termination of processes while there are pages in the balloon.
312 * If virtio balloon manages to release some memory, it will make the
313 * system return and retry the allocation that forced the OOM killer
314 * to run.
315 */
316static int virtballoon_oom_notify(struct notifier_block *self,
317 unsigned long dummy, void *parm)
318{
319 struct virtio_balloon *vb;
320 unsigned long *freed;
321 unsigned num_freed_pages;
322
323 vb = container_of(self, struct virtio_balloon, nb);
324 if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
325 return NOTIFY_OK;
326
327 freed = parm;
328 num_freed_pages = leak_balloon(vb, oom_pages);
329 update_balloon_size(vb);
330 *freed += num_freed_pages;
331
332 return NOTIFY_OK;
333}
334
Rusty Russell6b35e402008-02-04 23:50:12 -0500335static int balloon(void *_vballoon)
336{
337 struct virtio_balloon *vb = _vballoon;
338
339 set_freezable();
340 while (!kthread_should_stop()) {
Rusty Russellbdc16812008-03-17 22:58:15 -0500341 s64 diff;
Rusty Russell6b35e402008-02-04 23:50:12 -0500342
343 try_to_freeze();
344 wait_event_interruptible(vb->config_change,
345 (diff = towards_target(vb)) != 0
Adam Litke1f34c712009-12-10 16:35:15 -0600346 || vb->need_stats_update
Marcelo Tosatti84a139a2009-04-16 21:14:04 -0300347 || kthread_should_stop()
348 || freezing(current));
Adam Litke1f34c712009-12-10 16:35:15 -0600349 if (vb->need_stats_update)
350 stats_handle_request(vb);
Rusty Russell6b35e402008-02-04 23:50:12 -0500351 if (diff > 0)
352 fill_balloon(vb, diff);
353 else if (diff < 0)
354 leak_balloon(vb, -diff);
355 update_balloon_size(vb);
Rusty Russell1f74ef02014-03-13 11:23:38 +1030356
357 /*
358 * For large balloon changes, we could spend a lot of time
359 * and always have work to do. Be nice if preempt disabled.
360 */
361 cond_resched();
Rusty Russell6b35e402008-02-04 23:50:12 -0500362 }
363 return 0;
364}
365
Amit Shahbe91c332011-12-22 16:58:34 +0530366static int init_vqs(struct virtio_balloon *vb)
Rusty Russell6b35e402008-02-04 23:50:12 -0500367{
Adam Litke9564e132009-11-30 10:14:15 -0600368 struct virtqueue *vqs[3];
Adam Litke1f34c712009-12-10 16:35:15 -0600369 vq_callback_t *callbacks[] = { balloon_ack, balloon_ack, stats_request };
Adam Litke9564e132009-11-30 10:14:15 -0600370 const char *names[] = { "inflate", "deflate", "stats" };
371 int err, nvqs;
Rusty Russell6b35e402008-02-04 23:50:12 -0500372
Amit Shahbe91c332011-12-22 16:58:34 +0530373 /*
374 * We expect two virtqueues: inflate and deflate, and
375 * optionally stat.
376 */
Adam Litke9564e132009-11-30 10:14:15 -0600377 nvqs = virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ) ? 3 : 2;
Amit Shahbe91c332011-12-22 16:58:34 +0530378 err = vb->vdev->config->find_vqs(vb->vdev, nvqs, vqs, callbacks, names);
Michael S. Tsirkind2a7ddd2009-06-12 22:16:36 -0600379 if (err)
Amit Shahbe91c332011-12-22 16:58:34 +0530380 return err;
Rusty Russell6b35e402008-02-04 23:50:12 -0500381
Michael S. Tsirkind2a7ddd2009-06-12 22:16:36 -0600382 vb->inflate_vq = vqs[0];
383 vb->deflate_vq = vqs[1];
Adam Litke9564e132009-11-30 10:14:15 -0600384 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {
385 struct scatterlist sg;
386 vb->stats_vq = vqs[2];
387
388 /*
389 * Prime this virtqueue with one buffer so the hypervisor can
Rusty Russell4951cc92014-03-13 11:23:40 +1030390 * use it to signal us later (it can't be broken yet!).
Adam Litke9564e132009-11-30 10:14:15 -0600391 */
392 sg_init_one(&sg, vb->stats, sizeof vb->stats);
Rusty Russell92549ab2013-03-20 15:44:30 +1030393 if (virtqueue_add_outbuf(vb->stats_vq, &sg, 1, vb, GFP_KERNEL)
Rusty Russellf96fde42012-01-12 15:44:42 +1030394 < 0)
Adam Litke9564e132009-11-30 10:14:15 -0600395 BUG();
Michael S. Tsirkin946cfe02010-04-12 16:18:28 +0300396 virtqueue_kick(vb->stats_vq);
Adam Litke9564e132009-11-30 10:14:15 -0600397 }
Amit Shahbe91c332011-12-22 16:58:34 +0530398 return 0;
399}
400
Rafael Aquinie2250422012-12-11 16:02:45 -0800401#ifdef CONFIG_BALLOON_COMPACTION
402/*
403 * virtballoon_migratepage - perform the balloon page migration on behalf of
404 * a compation thread. (called under page lock)
Konstantin Khlebnikov9d1ba802014-10-09 15:29:29 -0700405 * @vb_dev_info: the balloon device
Rafael Aquinie2250422012-12-11 16:02:45 -0800406 * @newpage: page that will replace the isolated page after migration finishes.
407 * @page : the isolated (old) page that is about to be migrated to newpage.
408 * @mode : compaction mode -- not used for balloon page migration.
409 *
410 * After a ballooned page gets isolated by compaction procedures, this is the
411 * function that performs the page migration on behalf of a compaction thread
412 * The page migration for virtio balloon is done in a simple swap fashion which
413 * follows these two macro steps:
414 * 1) insert newpage into vb->pages list and update the host about it;
415 * 2) update the host about the old page removed from vb->pages list;
416 *
417 * This function preforms the balloon page migration task.
418 * Called through balloon_mapping->a_ops->migratepage
419 */
Konstantin Khlebnikov9d1ba802014-10-09 15:29:29 -0700420static int virtballoon_migratepage(struct balloon_dev_info *vb_dev_info,
Rafael Aquinie2250422012-12-11 16:02:45 -0800421 struct page *newpage, struct page *page, enum migrate_mode mode)
422{
Konstantin Khlebnikov9d1ba802014-10-09 15:29:29 -0700423 struct virtio_balloon *vb = container_of(vb_dev_info,
424 struct virtio_balloon, vb_dev_info);
Rafael Aquinie2250422012-12-11 16:02:45 -0800425 unsigned long flags;
426
Rafael Aquinie2250422012-12-11 16:02:45 -0800427 /*
428 * In order to avoid lock contention while migrating pages concurrently
429 * to leak_balloon() or fill_balloon() we just give up the balloon_lock
430 * this turn, as it is easier to retry the page migration later.
431 * This also prevents fill_balloon() getting stuck into a mutex
432 * recursion in the case it ends up triggering memory compaction
433 * while it is attempting to inflate the ballon.
434 */
435 if (!mutex_trylock(&vb->balloon_lock))
436 return -EAGAIN;
437
Konstantin Khlebnikovd6d86c02014-10-09 15:29:27 -0700438 get_page(newpage); /* balloon reference */
439
Rafael Aquinie2250422012-12-11 16:02:45 -0800440 /* balloon's page migration 1st step -- inflate "newpage" */
441 spin_lock_irqsave(&vb_dev_info->pages_lock, flags);
Konstantin Khlebnikov9d1ba802014-10-09 15:29:29 -0700442 balloon_page_insert(vb_dev_info, newpage);
Rafael Aquinie2250422012-12-11 16:02:45 -0800443 vb_dev_info->isolated_pages--;
Konstantin Khlebnikov09316c02014-10-09 15:29:32 -0700444 __count_vm_event(BALLOON_MIGRATE);
Rafael Aquinie2250422012-12-11 16:02:45 -0800445 spin_unlock_irqrestore(&vb_dev_info->pages_lock, flags);
446 vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE;
447 set_page_pfns(vb->pfns, newpage);
448 tell_host(vb, vb->inflate_vq);
449
Konstantin Khlebnikovd6d86c02014-10-09 15:29:27 -0700450 /* balloon's page migration 2nd step -- deflate "page" */
Rafael Aquinie2250422012-12-11 16:02:45 -0800451 balloon_page_delete(page);
452 vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE;
453 set_page_pfns(vb->pfns, page);
454 tell_host(vb, vb->deflate_vq);
455
456 mutex_unlock(&vb->balloon_lock);
457
Konstantin Khlebnikovd6d86c02014-10-09 15:29:27 -0700458 put_page(page); /* balloon reference */
459
460 return MIGRATEPAGE_SUCCESS;
Rafael Aquinie2250422012-12-11 16:02:45 -0800461}
Rafael Aquinie2250422012-12-11 16:02:45 -0800462#endif /* CONFIG_BALLOON_COMPACTION */
463
Amit Shahbe91c332011-12-22 16:58:34 +0530464static int virtballoon_probe(struct virtio_device *vdev)
465{
466 struct virtio_balloon *vb;
467 int err;
468
469 vdev->priv = vb = kmalloc(sizeof(*vb), GFP_KERNEL);
470 if (!vb) {
471 err = -ENOMEM;
472 goto out;
473 }
474
Amit Shahbe91c332011-12-22 16:58:34 +0530475 vb->num_pages = 0;
Rafael Aquinie2250422012-12-11 16:02:45 -0800476 mutex_init(&vb->balloon_lock);
Amit Shahbe91c332011-12-22 16:58:34 +0530477 init_waitqueue_head(&vb->config_change);
Michael S. Tsirkin9c378ab2012-07-02 10:33:08 +0300478 init_waitqueue_head(&vb->acked);
Amit Shahbe91c332011-12-22 16:58:34 +0530479 vb->vdev = vdev;
480 vb->need_stats_update = 0;
481
Konstantin Khlebnikov9d1ba802014-10-09 15:29:29 -0700482 balloon_devinfo_init(&vb->vb_dev_info);
483#ifdef CONFIG_BALLOON_COMPACTION
484 vb->vb_dev_info.migratepage = virtballoon_migratepage;
485#endif
Rafael Aquinie2250422012-12-11 16:02:45 -0800486
Amit Shahbe91c332011-12-22 16:58:34 +0530487 err = init_vqs(vb);
488 if (err)
Konstantin Khlebnikov9d1ba802014-10-09 15:29:29 -0700489 goto out_free_vb;
Rusty Russell6b35e402008-02-04 23:50:12 -0500490
Raushaniya Maksudova5a10b7d2014-11-10 09:36:29 +1030491 vb->nb.notifier_call = virtballoon_oom_notify;
492 vb->nb.priority = VIRTBALLOON_OOM_NOTIFY_PRIORITY;
493 err = register_oom_notifier(&vb->nb);
494 if (err < 0)
495 goto out_oom_notify;
496
Rusty Russell6b35e402008-02-04 23:50:12 -0500497 vb->thread = kthread_run(balloon, vb, "vballoon");
498 if (IS_ERR(vb->thread)) {
499 err = PTR_ERR(vb->thread);
Michael S. Tsirkind2a7ddd2009-06-12 22:16:36 -0600500 goto out_del_vqs;
Rusty Russell6b35e402008-02-04 23:50:12 -0500501 }
502
Rusty Russell6b35e402008-02-04 23:50:12 -0500503 return 0;
504
Michael S. Tsirkind2a7ddd2009-06-12 22:16:36 -0600505out_del_vqs:
Raushaniya Maksudova5a10b7d2014-11-10 09:36:29 +1030506 unregister_oom_notifier(&vb->nb);
507out_oom_notify:
Michael S. Tsirkind2a7ddd2009-06-12 22:16:36 -0600508 vdev->config->del_vqs(vdev);
Rusty Russell6b35e402008-02-04 23:50:12 -0500509out_free_vb:
510 kfree(vb);
511out:
512 return err;
513}
514
Amit Shahc877bab2012-04-27 00:45:57 +0530515static void remove_common(struct virtio_balloon *vb)
Rusty Russell6b35e402008-02-04 23:50:12 -0500516{
Rusty Russell6b35e402008-02-04 23:50:12 -0500517 /* There might be pages left in the balloon: free them. */
518 while (vb->num_pages)
519 leak_balloon(vb, vb->num_pages);
Amit Shahb8ae0eb2012-04-27 00:45:56 +0530520 update_balloon_size(vb);
Rusty Russell6b35e402008-02-04 23:50:12 -0500521
522 /* Now we reset the device so we can clean up the queues. */
Amit Shahc877bab2012-04-27 00:45:57 +0530523 vb->vdev->config->reset(vb->vdev);
Rusty Russell6b35e402008-02-04 23:50:12 -0500524
Amit Shahc877bab2012-04-27 00:45:57 +0530525 vb->vdev->config->del_vqs(vb->vdev);
526}
527
Greg Kroah-Hartman8590dbc2012-12-21 13:05:30 -0800528static void virtballoon_remove(struct virtio_device *vdev)
Amit Shahc877bab2012-04-27 00:45:57 +0530529{
530 struct virtio_balloon *vb = vdev->priv;
531
Raushaniya Maksudova5a10b7d2014-11-10 09:36:29 +1030532 unregister_oom_notifier(&vb->nb);
Amit Shahc877bab2012-04-27 00:45:57 +0530533 kthread_stop(vb->thread);
534 remove_common(vb);
Rusty Russell6b35e402008-02-04 23:50:12 -0500535 kfree(vb);
536}
537
Aaron Lu89107002013-09-17 09:25:23 +0930538#ifdef CONFIG_PM_SLEEP
Amit Shahe5629662011-12-22 16:58:35 +0530539static int virtballoon_freeze(struct virtio_device *vdev)
540{
Amit Shah4eb05d52012-02-29 17:42:51 +0530541 struct virtio_balloon *vb = vdev->priv;
542
Amit Shahe5629662011-12-22 16:58:35 +0530543 /*
544 * The kthread is already frozen by the PM core before this
545 * function is called.
546 */
547
Amit Shahc877bab2012-04-27 00:45:57 +0530548 remove_common(vb);
Amit Shahe5629662011-12-22 16:58:35 +0530549 return 0;
550}
551
Amit Shahc45b4162012-04-27 00:45:55 +0530552static int virtballoon_restore(struct virtio_device *vdev)
Amit Shah4eb05d52012-02-29 17:42:51 +0530553{
554 struct virtio_balloon *vb = vdev->priv;
555 int ret;
556
557 ret = init_vqs(vdev->priv);
558 if (ret)
559 return ret;
560
Michael S. Tsirkin486d2e62014-10-15 10:22:33 +1030561 virtio_device_ready(vdev);
562
Amit Shah4eb05d52012-02-29 17:42:51 +0530563 fill_balloon(vb, towards_target(vb));
564 update_balloon_size(vb);
565 return 0;
566}
Amit Shahe5629662011-12-22 16:58:35 +0530567#endif
568
Adam Litke9564e132009-11-30 10:14:15 -0600569static unsigned int features[] = {
570 VIRTIO_BALLOON_F_MUST_TELL_HOST,
571 VIRTIO_BALLOON_F_STATS_VQ,
Raushaniya Maksudova5a10b7d2014-11-10 09:36:29 +1030572 VIRTIO_BALLOON_F_DEFLATE_ON_OOM,
Adam Litke9564e132009-11-30 10:14:15 -0600573};
Rusty Russellc45a6812008-05-02 21:50:50 -0500574
Jeff Mahoneyd817cd52010-01-15 17:01:26 -0800575static struct virtio_driver virtio_balloon_driver = {
Rusty Russellc45a6812008-05-02 21:50:50 -0500576 .feature_table = features,
577 .feature_table_size = ARRAY_SIZE(features),
Rusty Russell6b35e402008-02-04 23:50:12 -0500578 .driver.name = KBUILD_MODNAME,
579 .driver.owner = THIS_MODULE,
580 .id_table = id_table,
581 .probe = virtballoon_probe,
Greg Kroah-Hartman8590dbc2012-12-21 13:05:30 -0800582 .remove = virtballoon_remove,
Rusty Russell6b35e402008-02-04 23:50:12 -0500583 .config_changed = virtballoon_changed,
Aaron Lu89107002013-09-17 09:25:23 +0930584#ifdef CONFIG_PM_SLEEP
Amit Shahe5629662011-12-22 16:58:35 +0530585 .freeze = virtballoon_freeze,
586 .restore = virtballoon_restore,
Amit Shahe5629662011-12-22 16:58:35 +0530587#endif
Rusty Russell6b35e402008-02-04 23:50:12 -0500588};
589
Rusty Russellb2a17022013-02-13 16:59:28 +1030590module_virtio_driver(virtio_balloon_driver);
Rusty Russell6b35e402008-02-04 23:50:12 -0500591MODULE_DEVICE_TABLE(virtio, id_table);
592MODULE_DESCRIPTION("Virtio balloon driver");
593MODULE_LICENSE("GPL");