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1/* Virtio balloon implementation, inspired by Dor Loar and Marcelo
2 * Tosatti's implementations.
3 *
4 * Copyright 2008 Rusty Russell IBM Corporation
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20//#define DEBUG
21#include <linux/virtio.h>
22#include <linux/virtio_balloon.h>
23#include <linux/swap.h>
24#include <linux/kthread.h>
25#include <linux/freezer.h>
26#include <linux/delay.h>
27#include <linux/slab.h>
28
29struct virtio_balloon
30{
31 struct virtio_device *vdev;
32 struct virtqueue *inflate_vq, *deflate_vq, *stats_vq;
33
34 /* Where the ballooning thread waits for config to change. */
35 wait_queue_head_t config_change;
36
37 /* The thread servicing the balloon. */
38 struct task_struct *thread;
39
40 /* Waiting for host to ack the pages we released. */
41 struct completion acked;
42
43 /* The pages we've told the Host we're not using. */
44 unsigned int num_pages;
45 struct list_head pages;
46
47 /* The array of pfns we tell the Host about. */
48 unsigned int num_pfns;
49 u32 pfns[256];
50
51 /* Memory statistics */
52 int need_stats_update;
53 struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR];
54};
55
56static struct virtio_device_id id_table[] = {
57 { VIRTIO_ID_BALLOON, VIRTIO_DEV_ANY_ID },
58 { 0 },
59};
60
61static u32 page_to_balloon_pfn(struct page *page)
62{
63 unsigned long pfn = page_to_pfn(page);
64
65 BUILD_BUG_ON(PAGE_SHIFT < VIRTIO_BALLOON_PFN_SHIFT);
66 /* Convert pfn from Linux page size to balloon page size. */
67 return pfn >> (PAGE_SHIFT - VIRTIO_BALLOON_PFN_SHIFT);
68}
69
70static void balloon_ack(struct virtqueue *vq)
71{
72 struct virtio_balloon *vb;
73 unsigned int len;
74
75 vb = virtqueue_get_buf(vq, &len);
76 if (vb)
77 complete(&vb->acked);
78}
79
80static void tell_host(struct virtio_balloon *vb, struct virtqueue *vq)
81{
82 struct scatterlist sg;
83
84 sg_init_one(&sg, vb->pfns, sizeof(vb->pfns[0]) * vb->num_pfns);
85
86 init_completion(&vb->acked);
87
88 /* We should always be able to add one buffer to an empty queue. */
89 if (virtqueue_add_buf(vq, &sg, 1, 0, vb) < 0)
90 BUG();
91 virtqueue_kick(vq);
92
93 /* When host has read buffer, this completes via balloon_ack */
94 wait_for_completion(&vb->acked);
95}
96
97static void fill_balloon(struct virtio_balloon *vb, size_t num)
98{
99 /* We can only do one array worth at a time. */
100 num = min(num, ARRAY_SIZE(vb->pfns));
101
102 for (vb->num_pfns = 0; vb->num_pfns < num; vb->num_pfns++) {
103 struct page *page = alloc_page(GFP_HIGHUSER | __GFP_NORETRY |
104 __GFP_NOMEMALLOC | __GFP_NOWARN);
105 if (!page) {
106 if (printk_ratelimit())
107 dev_printk(KERN_INFO, &vb->vdev->dev,
108 "Out of puff! Can't get %zu pages\n",
109 num);
110 /* Sleep for at least 1/5 of a second before retry. */
111 msleep(200);
112 break;
113 }
114 vb->pfns[vb->num_pfns] = page_to_balloon_pfn(page);
115 totalram_pages--;
116 vb->num_pages++;
117 list_add(&page->lru, &vb->pages);
118 }
119
120 /* Didn't get any? Oh well. */
121 if (vb->num_pfns == 0)
122 return;
123
124 tell_host(vb, vb->inflate_vq);
125}
126
127static void release_pages_by_pfn(const u32 pfns[], unsigned int num)
128{
129 unsigned int i;
130
131 for (i = 0; i < num; i++) {
132 __free_page(pfn_to_page(pfns[i]));
133 totalram_pages++;
134 }
135}
136
137static void leak_balloon(struct virtio_balloon *vb, size_t num)
138{
139 struct page *page;
140
141 /* We can only do one array worth at a time. */
142 num = min(num, ARRAY_SIZE(vb->pfns));
143
144 for (vb->num_pfns = 0; vb->num_pfns < num; vb->num_pfns++) {
145 page = list_first_entry(&vb->pages, struct page, lru);
146 list_del(&page->lru);
147 vb->pfns[vb->num_pfns] = page_to_balloon_pfn(page);
148 vb->num_pages--;
149 }
150
151
152 /*
153 * Note that if
154 * virtio_has_feature(vdev, VIRTIO_BALLOON_F_MUST_TELL_HOST);
155 * is true, we *have* to do it in this order
156 */
157 tell_host(vb, vb->deflate_vq);
158 release_pages_by_pfn(vb->pfns, vb->num_pfns);
159}
160
161static inline void update_stat(struct virtio_balloon *vb, int idx,
162 u16 tag, u64 val)
163{
164 BUG_ON(idx >= VIRTIO_BALLOON_S_NR);
165 vb->stats[idx].tag = tag;
166 vb->stats[idx].val = val;
167}
168
169#define pages_to_bytes(x) ((u64)(x) << PAGE_SHIFT)
170
171static void update_balloon_stats(struct virtio_balloon *vb)
172{
173 unsigned long events[NR_VM_EVENT_ITEMS];
174 struct sysinfo i;
175 int idx = 0;
176
177 all_vm_events(events);
178 si_meminfo(&i);
179
180 update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_IN,
181 pages_to_bytes(events[PSWPIN]));
182 update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_OUT,
183 pages_to_bytes(events[PSWPOUT]));
184 update_stat(vb, idx++, VIRTIO_BALLOON_S_MAJFLT, events[PGMAJFAULT]);
185 update_stat(vb, idx++, VIRTIO_BALLOON_S_MINFLT, events[PGFAULT]);
186 update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMFREE,
187 pages_to_bytes(i.freeram));
188 update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMTOT,
189 pages_to_bytes(i.totalram));
190}
191
192/*
193 * While most virtqueues communicate guest-initiated requests to the hypervisor,
194 * the stats queue operates in reverse. The driver initializes the virtqueue
195 * with a single buffer. From that point forward, all conversations consist of
196 * a hypervisor request (a call to this function) which directs us to refill
197 * the virtqueue with a fresh stats buffer. Since stats collection can sleep,
198 * we notify our kthread which does the actual work via stats_handle_request().
199 */
200static void stats_request(struct virtqueue *vq)
201{
202 struct virtio_balloon *vb;
203 unsigned int len;
204
205 vb = virtqueue_get_buf(vq, &len);
206 if (!vb)
207 return;
208 vb->need_stats_update = 1;
209 wake_up(&vb->config_change);
210}
211
212static void stats_handle_request(struct virtio_balloon *vb)
213{
214 struct virtqueue *vq;
215 struct scatterlist sg;
216
217 vb->need_stats_update = 0;
218 update_balloon_stats(vb);
219
220 vq = vb->stats_vq;
221 sg_init_one(&sg, vb->stats, sizeof(vb->stats));
222 if (virtqueue_add_buf(vq, &sg, 1, 0, vb) < 0)
223 BUG();
224 virtqueue_kick(vq);
225}
226
227static void virtballoon_changed(struct virtio_device *vdev)
228{
229 struct virtio_balloon *vb = vdev->priv;
230
231 wake_up(&vb->config_change);
232}
233
234static inline s64 towards_target(struct virtio_balloon *vb)
235{
236 u32 v;
237 vb->vdev->config->get(vb->vdev,
238 offsetof(struct virtio_balloon_config, num_pages),
239 &v, sizeof(v));
240 return (s64)v - vb->num_pages;
241}
242
243static void update_balloon_size(struct virtio_balloon *vb)
244{
245 __le32 actual = cpu_to_le32(vb->num_pages);
246
247 vb->vdev->config->set(vb->vdev,
248 offsetof(struct virtio_balloon_config, actual),
249 &actual, sizeof(actual));
250}
251
252static int balloon(void *_vballoon)
253{
254 struct virtio_balloon *vb = _vballoon;
255
256 set_freezable();
257 while (!kthread_should_stop()) {
258 s64 diff;
259
260 try_to_freeze();
261 wait_event_interruptible(vb->config_change,
262 (diff = towards_target(vb)) != 0
263 || vb->need_stats_update
264 || kthread_should_stop()
265 || freezing(current));
266 if (vb->need_stats_update)
267 stats_handle_request(vb);
268 if (diff > 0)
269 fill_balloon(vb, diff);
270 else if (diff < 0)
271 leak_balloon(vb, -diff);
272 update_balloon_size(vb);
273 }
274 return 0;
275}
276
277static int virtballoon_probe(struct virtio_device *vdev)
278{
279 struct virtio_balloon *vb;
280 struct virtqueue *vqs[3];
281 vq_callback_t *callbacks[] = { balloon_ack, balloon_ack, stats_request };
282 const char *names[] = { "inflate", "deflate", "stats" };
283 int err, nvqs;
284
285 vdev->priv = vb = kmalloc(sizeof(*vb), GFP_KERNEL);
286 if (!vb) {
287 err = -ENOMEM;
288 goto out;
289 }
290
291 INIT_LIST_HEAD(&vb->pages);
292 vb->num_pages = 0;
293 init_waitqueue_head(&vb->config_change);
294 vb->vdev = vdev;
295 vb->need_stats_update = 0;
296
297 /* We expect two virtqueues: inflate and deflate,
298 * and optionally stat. */
299 nvqs = virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ) ? 3 : 2;
300 err = vdev->config->find_vqs(vdev, nvqs, vqs, callbacks, names);
301 if (err)
302 goto out_free_vb;
303
304 vb->inflate_vq = vqs[0];
305 vb->deflate_vq = vqs[1];
306 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {
307 struct scatterlist sg;
308 vb->stats_vq = vqs[2];
309
310 /*
311 * Prime this virtqueue with one buffer so the hypervisor can
312 * use it to signal us later.
313 */
314 sg_init_one(&sg, vb->stats, sizeof vb->stats);
315 if (virtqueue_add_buf(vb->stats_vq, &sg, 1, 0, vb) < 0)
316 BUG();
317 virtqueue_kick(vb->stats_vq);
318 }
319
320 vb->thread = kthread_run(balloon, vb, "vballoon");
321 if (IS_ERR(vb->thread)) {
322 err = PTR_ERR(vb->thread);
323 goto out_del_vqs;
324 }
325
326 return 0;
327
328out_del_vqs:
329 vdev->config->del_vqs(vdev);
330out_free_vb:
331 kfree(vb);
332out:
333 return err;
334}
335
336static void __devexit virtballoon_remove(struct virtio_device *vdev)
337{
338 struct virtio_balloon *vb = vdev->priv;
339
340 kthread_stop(vb->thread);
341
342 /* There might be pages left in the balloon: free them. */
343 while (vb->num_pages)
344 leak_balloon(vb, vb->num_pages);
345
346 /* Now we reset the device so we can clean up the queues. */
347 vdev->config->reset(vdev);
348
349 vdev->config->del_vqs(vdev);
350 kfree(vb);
351}
352
353static unsigned int features[] = {
354 VIRTIO_BALLOON_F_MUST_TELL_HOST,
355 VIRTIO_BALLOON_F_STATS_VQ,
356};
357
358static struct virtio_driver virtio_balloon_driver = {
359 .feature_table = features,
360 .feature_table_size = ARRAY_SIZE(features),
361 .driver.name = KBUILD_MODNAME,
362 .driver.owner = THIS_MODULE,
363 .id_table = id_table,
364 .probe = virtballoon_probe,
365 .remove = __devexit_p(virtballoon_remove),
366 .config_changed = virtballoon_changed,
367};
368
369static int __init init(void)
370{
371 return register_virtio_driver(&virtio_balloon_driver);
372}
373
374static void __exit fini(void)
375{
376 unregister_virtio_driver(&virtio_balloon_driver);
377}
378module_init(init);
379module_exit(fini);
380
381MODULE_DEVICE_TABLE(virtio, id_table);
382MODULE_DESCRIPTION("Virtio balloon driver");
383MODULE_LICENSE("GPL");
1/*
2 * Virtio balloon implementation, inspired by Dor Laor and Marcelo
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 */
21
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>
27#include <linux/delay.h>
28#include <linux/slab.h>
29#include <linux/module.h>
30
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
38struct virtio_balloon
39{
40 struct virtio_device *vdev;
41 struct virtqueue *inflate_vq, *deflate_vq, *stats_vq;
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 wait_queue_head_t acked;
51
52 /* Number of balloon pages we've told the Host we're not using. */
53 unsigned int num_pages;
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 */
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];
64
65 /* Memory statistics */
66 int need_stats_update;
67 struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR];
68};
69
70static struct virtio_device_id id_table[] = {
71 { VIRTIO_ID_BALLOON, VIRTIO_DEV_ANY_ID },
72 { 0 },
73};
74
75static 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. */
81 return pfn * VIRTIO_BALLOON_PAGES_PER_PAGE;
82}
83
84static 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);
88}
89
90static void balloon_ack(struct virtqueue *vq)
91{
92 struct virtio_balloon *vb = vq->vdev->priv;
93
94 wake_up(&vb->acked);
95}
96
97static void tell_host(struct virtio_balloon *vb, struct virtqueue *vq)
98{
99 struct scatterlist sg;
100 unsigned int len;
101
102 sg_init_one(&sg, vb->pfns, sizeof(vb->pfns[0]) * vb->num_pfns);
103
104 /* We should always be able to add one buffer to an empty queue. */
105 if (virtqueue_add_buf(vq, &sg, 1, 0, vb, GFP_KERNEL) < 0)
106 BUG();
107 virtqueue_kick(vq);
108
109 /* When host has read buffer, this completes via balloon_ack */
110 wait_event(vb->acked, virtqueue_get_buf(vq, &len));
111}
112
113static void set_page_pfns(u32 pfns[], struct page *page)
114{
115 unsigned int i;
116
117 /* Set balloon pfns pointing at this page.
118 * Note that the first pfn points at start of the page. */
119 for (i = 0; i < VIRTIO_BALLOON_PAGES_PER_PAGE; i++)
120 pfns[i] = page_to_balloon_pfn(page) + i;
121}
122
123static void fill_balloon(struct virtio_balloon *vb, size_t num)
124{
125 /* We can only do one array worth at a time. */
126 num = min(num, ARRAY_SIZE(vb->pfns));
127
128 for (vb->num_pfns = 0; vb->num_pfns < num;
129 vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) {
130 struct page *page = alloc_page(GFP_HIGHUSER | __GFP_NORETRY |
131 __GFP_NOMEMALLOC | __GFP_NOWARN);
132 if (!page) {
133 if (printk_ratelimit())
134 dev_printk(KERN_INFO, &vb->vdev->dev,
135 "Out of puff! Can't get %zu pages\n",
136 num);
137 /* Sleep for at least 1/5 of a second before retry. */
138 msleep(200);
139 break;
140 }
141 set_page_pfns(vb->pfns + vb->num_pfns, page);
142 vb->num_pages += VIRTIO_BALLOON_PAGES_PER_PAGE;
143 totalram_pages--;
144 list_add(&page->lru, &vb->pages);
145 }
146
147 /* Didn't get any? Oh well. */
148 if (vb->num_pfns == 0)
149 return;
150
151 tell_host(vb, vb->inflate_vq);
152}
153
154static void release_pages_by_pfn(const u32 pfns[], unsigned int num)
155{
156 unsigned int i;
157
158 /* Find pfns pointing at start of each page, get pages and free them. */
159 for (i = 0; i < num; i += VIRTIO_BALLOON_PAGES_PER_PAGE) {
160 __free_page(balloon_pfn_to_page(pfns[i]));
161 totalram_pages++;
162 }
163}
164
165static void leak_balloon(struct virtio_balloon *vb, size_t num)
166{
167 struct page *page;
168
169 /* We can only do one array worth at a time. */
170 num = min(num, ARRAY_SIZE(vb->pfns));
171
172 for (vb->num_pfns = 0; vb->num_pfns < num;
173 vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) {
174 page = list_first_entry(&vb->pages, struct page, lru);
175 list_del(&page->lru);
176 set_page_pfns(vb->pfns + vb->num_pfns, page);
177 vb->num_pages -= VIRTIO_BALLOON_PAGES_PER_PAGE;
178 }
179
180 /*
181 * Note that if
182 * virtio_has_feature(vdev, VIRTIO_BALLOON_F_MUST_TELL_HOST);
183 * is true, we *have* to do it in this order
184 */
185 tell_host(vb, vb->deflate_vq);
186 release_pages_by_pfn(vb->pfns, vb->num_pfns);
187}
188
189static inline void update_stat(struct virtio_balloon *vb, int idx,
190 u16 tag, u64 val)
191{
192 BUG_ON(idx >= VIRTIO_BALLOON_S_NR);
193 vb->stats[idx].tag = tag;
194 vb->stats[idx].val = val;
195}
196
197#define pages_to_bytes(x) ((u64)(x) << PAGE_SHIFT)
198
199static void update_balloon_stats(struct virtio_balloon *vb)
200{
201 unsigned long events[NR_VM_EVENT_ITEMS];
202 struct sysinfo i;
203 int idx = 0;
204
205 all_vm_events(events);
206 si_meminfo(&i);
207
208 update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_IN,
209 pages_to_bytes(events[PSWPIN]));
210 update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_OUT,
211 pages_to_bytes(events[PSWPOUT]));
212 update_stat(vb, idx++, VIRTIO_BALLOON_S_MAJFLT, events[PGMAJFAULT]);
213 update_stat(vb, idx++, VIRTIO_BALLOON_S_MINFLT, events[PGFAULT]);
214 update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMFREE,
215 pages_to_bytes(i.freeram));
216 update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMTOT,
217 pages_to_bytes(i.totalram));
218}
219
220/*
221 * While most virtqueues communicate guest-initiated requests to the hypervisor,
222 * the stats queue operates in reverse. The driver initializes the virtqueue
223 * with a single buffer. From that point forward, all conversations consist of
224 * a hypervisor request (a call to this function) which directs us to refill
225 * the virtqueue with a fresh stats buffer. Since stats collection can sleep,
226 * we notify our kthread which does the actual work via stats_handle_request().
227 */
228static void stats_request(struct virtqueue *vq)
229{
230 struct virtio_balloon *vb = vq->vdev->priv;
231
232 vb->need_stats_update = 1;
233 wake_up(&vb->config_change);
234}
235
236static void stats_handle_request(struct virtio_balloon *vb)
237{
238 struct virtqueue *vq;
239 struct scatterlist sg;
240 unsigned int len;
241
242 vb->need_stats_update = 0;
243 update_balloon_stats(vb);
244
245 vq = vb->stats_vq;
246 if (!virtqueue_get_buf(vq, &len))
247 return;
248 sg_init_one(&sg, vb->stats, sizeof(vb->stats));
249 if (virtqueue_add_buf(vq, &sg, 1, 0, vb, GFP_KERNEL) < 0)
250 BUG();
251 virtqueue_kick(vq);
252}
253
254static void virtballoon_changed(struct virtio_device *vdev)
255{
256 struct virtio_balloon *vb = vdev->priv;
257
258 wake_up(&vb->config_change);
259}
260
261static inline s64 towards_target(struct virtio_balloon *vb)
262{
263 __le32 v;
264 s64 target;
265
266 vb->vdev->config->get(vb->vdev,
267 offsetof(struct virtio_balloon_config, num_pages),
268 &v, sizeof(v));
269 target = le32_to_cpu(v);
270 return target - vb->num_pages;
271}
272
273static void update_balloon_size(struct virtio_balloon *vb)
274{
275 __le32 actual = cpu_to_le32(vb->num_pages);
276
277 vb->vdev->config->set(vb->vdev,
278 offsetof(struct virtio_balloon_config, actual),
279 &actual, sizeof(actual));
280}
281
282static int balloon(void *_vballoon)
283{
284 struct virtio_balloon *vb = _vballoon;
285
286 set_freezable();
287 while (!kthread_should_stop()) {
288 s64 diff;
289
290 try_to_freeze();
291 wait_event_interruptible(vb->config_change,
292 (diff = towards_target(vb)) != 0
293 || vb->need_stats_update
294 || kthread_should_stop()
295 || freezing(current));
296 if (vb->need_stats_update)
297 stats_handle_request(vb);
298 if (diff > 0)
299 fill_balloon(vb, diff);
300 else if (diff < 0)
301 leak_balloon(vb, -diff);
302 update_balloon_size(vb);
303 }
304 return 0;
305}
306
307static int init_vqs(struct virtio_balloon *vb)
308{
309 struct virtqueue *vqs[3];
310 vq_callback_t *callbacks[] = { balloon_ack, balloon_ack, stats_request };
311 const char *names[] = { "inflate", "deflate", "stats" };
312 int err, nvqs;
313
314 /*
315 * We expect two virtqueues: inflate and deflate, and
316 * optionally stat.
317 */
318 nvqs = virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ) ? 3 : 2;
319 err = vb->vdev->config->find_vqs(vb->vdev, nvqs, vqs, callbacks, names);
320 if (err)
321 return err;
322
323 vb->inflate_vq = vqs[0];
324 vb->deflate_vq = vqs[1];
325 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {
326 struct scatterlist sg;
327 vb->stats_vq = vqs[2];
328
329 /*
330 * Prime this virtqueue with one buffer so the hypervisor can
331 * use it to signal us later.
332 */
333 sg_init_one(&sg, vb->stats, sizeof vb->stats);
334 if (virtqueue_add_buf(vb->stats_vq, &sg, 1, 0, vb, GFP_KERNEL)
335 < 0)
336 BUG();
337 virtqueue_kick(vb->stats_vq);
338 }
339 return 0;
340}
341
342static int virtballoon_probe(struct virtio_device *vdev)
343{
344 struct virtio_balloon *vb;
345 int err;
346
347 vdev->priv = vb = kmalloc(sizeof(*vb), GFP_KERNEL);
348 if (!vb) {
349 err = -ENOMEM;
350 goto out;
351 }
352
353 INIT_LIST_HEAD(&vb->pages);
354 vb->num_pages = 0;
355 init_waitqueue_head(&vb->config_change);
356 init_waitqueue_head(&vb->acked);
357 vb->vdev = vdev;
358 vb->need_stats_update = 0;
359
360 err = init_vqs(vb);
361 if (err)
362 goto out_free_vb;
363
364 vb->thread = kthread_run(balloon, vb, "vballoon");
365 if (IS_ERR(vb->thread)) {
366 err = PTR_ERR(vb->thread);
367 goto out_del_vqs;
368 }
369
370 return 0;
371
372out_del_vqs:
373 vdev->config->del_vqs(vdev);
374out_free_vb:
375 kfree(vb);
376out:
377 return err;
378}
379
380static void remove_common(struct virtio_balloon *vb)
381{
382 /* There might be pages left in the balloon: free them. */
383 while (vb->num_pages)
384 leak_balloon(vb, vb->num_pages);
385 update_balloon_size(vb);
386
387 /* Now we reset the device so we can clean up the queues. */
388 vb->vdev->config->reset(vb->vdev);
389
390 vb->vdev->config->del_vqs(vb->vdev);
391}
392
393static void __devexit virtballoon_remove(struct virtio_device *vdev)
394{
395 struct virtio_balloon *vb = vdev->priv;
396
397 kthread_stop(vb->thread);
398 remove_common(vb);
399 kfree(vb);
400}
401
402#ifdef CONFIG_PM
403static int virtballoon_freeze(struct virtio_device *vdev)
404{
405 struct virtio_balloon *vb = vdev->priv;
406
407 /*
408 * The kthread is already frozen by the PM core before this
409 * function is called.
410 */
411
412 remove_common(vb);
413 return 0;
414}
415
416static int virtballoon_restore(struct virtio_device *vdev)
417{
418 struct virtio_balloon *vb = vdev->priv;
419 int ret;
420
421 ret = init_vqs(vdev->priv);
422 if (ret)
423 return ret;
424
425 fill_balloon(vb, towards_target(vb));
426 update_balloon_size(vb);
427 return 0;
428}
429#endif
430
431static unsigned int features[] = {
432 VIRTIO_BALLOON_F_MUST_TELL_HOST,
433 VIRTIO_BALLOON_F_STATS_VQ,
434};
435
436static struct virtio_driver virtio_balloon_driver = {
437 .feature_table = features,
438 .feature_table_size = ARRAY_SIZE(features),
439 .driver.name = KBUILD_MODNAME,
440 .driver.owner = THIS_MODULE,
441 .id_table = id_table,
442 .probe = virtballoon_probe,
443 .remove = __devexit_p(virtballoon_remove),
444 .config_changed = virtballoon_changed,
445#ifdef CONFIG_PM
446 .freeze = virtballoon_freeze,
447 .restore = virtballoon_restore,
448#endif
449};
450
451static int __init init(void)
452{
453 return register_virtio_driver(&virtio_balloon_driver);
454}
455
456static void __exit fini(void)
457{
458 unregister_virtio_driver(&virtio_balloon_driver);
459}
460module_init(init);
461module_exit(fini);
462
463MODULE_DEVICE_TABLE(virtio, id_table);
464MODULE_DESCRIPTION("Virtio balloon driver");
465MODULE_LICENSE("GPL");