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/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> 33 #include <linux/mount.h> 34 35 /* 36 * Balloon device works in 4K page units. So each page is pointed to by 37 * multiple balloon pages. All memory counters in this driver are in balloon 38 * page units. 39 */ 40 #define VIRTIO_BALLOON_PAGES_PER_PAGE (unsigned)(PAGE_SIZE >> VIRTIO_BALLOON_PFN_SHIFT) 41 #define VIRTIO_BALLOON_ARRAY_PFNS_MAX 256 42 #define OOM_VBALLOON_DEFAULT_PAGES 256 43 #define VIRTBALLOON_OOM_NOTIFY_PRIORITY 80 44 45 static int oom_pages = OOM_VBALLOON_DEFAULT_PAGES; 46 module_param(oom_pages, int, S_IRUSR | S_IWUSR); 47 MODULE_PARM_DESC(oom_pages, "pages to free on OOM"); 48 49 #ifdef CONFIG_BALLOON_COMPACTION 50 static struct vfsmount *balloon_mnt; 51 #endif 52 53 struct virtio_balloon { 54 struct virtio_device *vdev; 55 struct virtqueue *inflate_vq, *deflate_vq, *stats_vq; 56 57 /* The balloon servicing is delegated to a freezable workqueue. */ 58 struct work_struct update_balloon_stats_work; 59 struct work_struct update_balloon_size_work; 60 61 /* Prevent updating balloon when it is being canceled. */ 62 spinlock_t stop_update_lock; 63 bool stop_update; 64 65 /* Waiting for host to ack the pages we released. */ 66 wait_queue_head_t acked; 67 68 /* Number of balloon pages we've told the Host we're not using. */ 69 unsigned int num_pages; 70 /* 71 * The pages we've told the Host we're not using are enqueued 72 * at vb_dev_info->pages list. 73 * Each page on this list adds VIRTIO_BALLOON_PAGES_PER_PAGE 74 * to num_pages above. 75 */ 76 struct balloon_dev_info vb_dev_info; 77 78 /* Synchronize access/update to this struct virtio_balloon elements */ 79 struct mutex balloon_lock; 80 81 /* The array of pfns we tell the Host about. */ 82 unsigned int num_pfns; 83 __virtio32 pfns[VIRTIO_BALLOON_ARRAY_PFNS_MAX]; 84 85 /* Memory statistics */ 86 struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR]; 87 88 /* To register callback in oom notifier call chain */ 89 struct notifier_block nb; 90 }; 91 92 static struct virtio_device_id id_table[] = { 93 { VIRTIO_ID_BALLOON, VIRTIO_DEV_ANY_ID }, 94 { 0 }, 95 }; 96 97 static u32 page_to_balloon_pfn(struct page *page) 98 { 99 unsigned long pfn = page_to_pfn(page); 100 101 BUILD_BUG_ON(PAGE_SHIFT < VIRTIO_BALLOON_PFN_SHIFT); 102 /* Convert pfn from Linux page size to balloon page size. */ 103 return pfn * VIRTIO_BALLOON_PAGES_PER_PAGE; 104 } 105 106 static struct page *balloon_pfn_to_page(u32 pfn) 107 { 108 BUG_ON(pfn % VIRTIO_BALLOON_PAGES_PER_PAGE); 109 return pfn_to_page(pfn / VIRTIO_BALLOON_PAGES_PER_PAGE); 110 } 111 112 static void balloon_ack(struct virtqueue *vq) 113 { 114 struct virtio_balloon *vb = vq->vdev->priv; 115 116 wake_up(&vb->acked); 117 } 118 119 static void tell_host(struct virtio_balloon *vb, struct virtqueue *vq) 120 { 121 struct scatterlist sg; 122 unsigned int len; 123 124 sg_init_one(&sg, vb->pfns, sizeof(vb->pfns[0]) * vb->num_pfns); 125 126 /* We should always be able to add one buffer to an empty queue. */ 127 virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL); 128 virtqueue_kick(vq); 129 130 /* When host has read buffer, this completes via balloon_ack */ 131 wait_event(vb->acked, virtqueue_get_buf(vq, &len)); 132 133 } 134 135 static void set_page_pfns(struct virtio_balloon *vb, 136 __virtio32 pfns[], struct page *page) 137 { 138 unsigned int i; 139 140 /* Set balloon pfns pointing at this page. 141 * Note that the first pfn points at start of the page. */ 142 for (i = 0; i < VIRTIO_BALLOON_PAGES_PER_PAGE; i++) 143 pfns[i] = cpu_to_virtio32(vb->vdev, 144 page_to_balloon_pfn(page) + i); 145 } 146 147 static unsigned fill_balloon(struct virtio_balloon *vb, size_t num) 148 { 149 struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info; 150 unsigned num_allocated_pages; 151 152 /* We can only do one array worth at a time. */ 153 num = min(num, ARRAY_SIZE(vb->pfns)); 154 155 mutex_lock(&vb->balloon_lock); 156 for (vb->num_pfns = 0; vb->num_pfns < num; 157 vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) { 158 struct page *page = balloon_page_enqueue(vb_dev_info); 159 160 if (!page) { 161 dev_info_ratelimited(&vb->vdev->dev, 162 "Out of puff! Can't get %u pages\n", 163 VIRTIO_BALLOON_PAGES_PER_PAGE); 164 /* Sleep for at least 1/5 of a second before retry. */ 165 msleep(200); 166 break; 167 } 168 set_page_pfns(vb, vb->pfns + vb->num_pfns, page); 169 vb->num_pages += VIRTIO_BALLOON_PAGES_PER_PAGE; 170 if (!virtio_has_feature(vb->vdev, 171 VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) 172 adjust_managed_page_count(page, -1); 173 } 174 175 num_allocated_pages = vb->num_pfns; 176 /* Did we get any? */ 177 if (vb->num_pfns != 0) 178 tell_host(vb, vb->inflate_vq); 179 mutex_unlock(&vb->balloon_lock); 180 181 return num_allocated_pages; 182 } 183 184 static void release_pages_balloon(struct virtio_balloon *vb) 185 { 186 unsigned int i; 187 struct page *page; 188 189 /* Find pfns pointing at start of each page, get pages and free them. */ 190 for (i = 0; i < vb->num_pfns; i += VIRTIO_BALLOON_PAGES_PER_PAGE) { 191 page = balloon_pfn_to_page(virtio32_to_cpu(vb->vdev, 192 vb->pfns[i])); 193 if (!virtio_has_feature(vb->vdev, 194 VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) 195 adjust_managed_page_count(page, 1); 196 put_page(page); /* balloon reference */ 197 } 198 } 199 200 static unsigned leak_balloon(struct virtio_balloon *vb, size_t num) 201 { 202 unsigned num_freed_pages; 203 struct page *page; 204 struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info; 205 206 /* We can only do one array worth at a time. */ 207 num = min(num, ARRAY_SIZE(vb->pfns)); 208 209 mutex_lock(&vb->balloon_lock); 210 /* We can't release more pages than taken */ 211 num = min(num, (size_t)vb->num_pages); 212 for (vb->num_pfns = 0; vb->num_pfns < num; 213 vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) { 214 page = balloon_page_dequeue(vb_dev_info); 215 if (!page) 216 break; 217 set_page_pfns(vb, vb->pfns + vb->num_pfns, page); 218 vb->num_pages -= VIRTIO_BALLOON_PAGES_PER_PAGE; 219 } 220 221 num_freed_pages = vb->num_pfns; 222 /* 223 * Note that if 224 * virtio_has_feature(vdev, VIRTIO_BALLOON_F_MUST_TELL_HOST); 225 * is true, we *have* to do it in this order 226 */ 227 if (vb->num_pfns != 0) 228 tell_host(vb, vb->deflate_vq); 229 release_pages_balloon(vb); 230 mutex_unlock(&vb->balloon_lock); 231 return num_freed_pages; 232 } 233 234 static inline void update_stat(struct virtio_balloon *vb, int idx, 235 u16 tag, u64 val) 236 { 237 BUG_ON(idx >= VIRTIO_BALLOON_S_NR); 238 vb->stats[idx].tag = cpu_to_virtio16(vb->vdev, tag); 239 vb->stats[idx].val = cpu_to_virtio64(vb->vdev, val); 240 } 241 242 #define pages_to_bytes(x) ((u64)(x) << PAGE_SHIFT) 243 244 static void update_balloon_stats(struct virtio_balloon *vb) 245 { 246 unsigned long events[NR_VM_EVENT_ITEMS]; 247 struct sysinfo i; 248 int idx = 0; 249 long available; 250 251 all_vm_events(events); 252 si_meminfo(&i); 253 254 available = si_mem_available(); 255 256 update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_IN, 257 pages_to_bytes(events[PSWPIN])); 258 update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_OUT, 259 pages_to_bytes(events[PSWPOUT])); 260 update_stat(vb, idx++, VIRTIO_BALLOON_S_MAJFLT, events[PGMAJFAULT]); 261 update_stat(vb, idx++, VIRTIO_BALLOON_S_MINFLT, events[PGFAULT]); 262 update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMFREE, 263 pages_to_bytes(i.freeram)); 264 update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMTOT, 265 pages_to_bytes(i.totalram)); 266 update_stat(vb, idx++, VIRTIO_BALLOON_S_AVAIL, 267 pages_to_bytes(available)); 268 } 269 270 /* 271 * While most virtqueues communicate guest-initiated requests to the hypervisor, 272 * the stats queue operates in reverse. The driver initializes the virtqueue 273 * with a single buffer. From that point forward, all conversations consist of 274 * a hypervisor request (a call to this function) which directs us to refill 275 * the virtqueue with a fresh stats buffer. Since stats collection can sleep, 276 * we delegate the job to a freezable workqueue that will do the actual work via 277 * stats_handle_request(). 278 */ 279 static void stats_request(struct virtqueue *vq) 280 { 281 struct virtio_balloon *vb = vq->vdev->priv; 282 283 spin_lock(&vb->stop_update_lock); 284 if (!vb->stop_update) 285 queue_work(system_freezable_wq, &vb->update_balloon_stats_work); 286 spin_unlock(&vb->stop_update_lock); 287 } 288 289 static void stats_handle_request(struct virtio_balloon *vb) 290 { 291 struct virtqueue *vq; 292 struct scatterlist sg; 293 unsigned int len; 294 295 update_balloon_stats(vb); 296 297 vq = vb->stats_vq; 298 if (!virtqueue_get_buf(vq, &len)) 299 return; 300 sg_init_one(&sg, vb->stats, sizeof(vb->stats)); 301 virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL); 302 virtqueue_kick(vq); 303 } 304 305 static void virtballoon_changed(struct virtio_device *vdev) 306 { 307 struct virtio_balloon *vb = vdev->priv; 308 unsigned long flags; 309 310 spin_lock_irqsave(&vb->stop_update_lock, flags); 311 if (!vb->stop_update) 312 queue_work(system_freezable_wq, &vb->update_balloon_size_work); 313 spin_unlock_irqrestore(&vb->stop_update_lock, flags); 314 } 315 316 static inline s64 towards_target(struct virtio_balloon *vb) 317 { 318 s64 target; 319 u32 num_pages; 320 321 virtio_cread(vb->vdev, struct virtio_balloon_config, num_pages, 322 &num_pages); 323 324 /* Legacy balloon config space is LE, unlike all other devices. */ 325 if (!virtio_has_feature(vb->vdev, VIRTIO_F_VERSION_1)) 326 num_pages = le32_to_cpu((__force __le32)num_pages); 327 328 target = num_pages; 329 return target - vb->num_pages; 330 } 331 332 static void update_balloon_size(struct virtio_balloon *vb) 333 { 334 u32 actual = vb->num_pages; 335 336 /* Legacy balloon config space is LE, unlike all other devices. */ 337 if (!virtio_has_feature(vb->vdev, VIRTIO_F_VERSION_1)) 338 actual = (__force u32)cpu_to_le32(actual); 339 340 virtio_cwrite(vb->vdev, struct virtio_balloon_config, actual, 341 &actual); 342 } 343 344 /* 345 * virtballoon_oom_notify - release pages when system is under severe 346 * memory pressure (called from out_of_memory()) 347 * @self : notifier block struct 348 * @dummy: not used 349 * @parm : returned - number of freed pages 350 * 351 * The balancing of memory by use of the virtio balloon should not cause 352 * the termination of processes while there are pages in the balloon. 353 * If virtio balloon manages to release some memory, it will make the 354 * system return and retry the allocation that forced the OOM killer 355 * to run. 356 */ 357 static int virtballoon_oom_notify(struct notifier_block *self, 358 unsigned long dummy, void *parm) 359 { 360 struct virtio_balloon *vb; 361 unsigned long *freed; 362 unsigned num_freed_pages; 363 364 vb = container_of(self, struct virtio_balloon, nb); 365 if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) 366 return NOTIFY_OK; 367 368 freed = parm; 369 num_freed_pages = leak_balloon(vb, oom_pages); 370 update_balloon_size(vb); 371 *freed += num_freed_pages; 372 373 return NOTIFY_OK; 374 } 375 376 static void update_balloon_stats_func(struct work_struct *work) 377 { 378 struct virtio_balloon *vb; 379 380 vb = container_of(work, struct virtio_balloon, 381 update_balloon_stats_work); 382 stats_handle_request(vb); 383 } 384 385 static void update_balloon_size_func(struct work_struct *work) 386 { 387 struct virtio_balloon *vb; 388 s64 diff; 389 390 vb = container_of(work, struct virtio_balloon, 391 update_balloon_size_work); 392 diff = towards_target(vb); 393 394 if (diff > 0) 395 diff -= fill_balloon(vb, diff); 396 else if (diff < 0) 397 diff += leak_balloon(vb, -diff); 398 update_balloon_size(vb); 399 400 if (diff) 401 queue_work(system_freezable_wq, work); 402 } 403 404 static int init_vqs(struct virtio_balloon *vb) 405 { 406 struct virtqueue *vqs[3]; 407 vq_callback_t *callbacks[] = { balloon_ack, balloon_ack, stats_request }; 408 static const char * const names[] = { "inflate", "deflate", "stats" }; 409 int err, nvqs; 410 411 /* 412 * We expect two virtqueues: inflate and deflate, and 413 * optionally stat. 414 */ 415 nvqs = virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ) ? 3 : 2; 416 err = vb->vdev->config->find_vqs(vb->vdev, nvqs, vqs, callbacks, names); 417 if (err) 418 return err; 419 420 vb->inflate_vq = vqs[0]; 421 vb->deflate_vq = vqs[1]; 422 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) { 423 struct scatterlist sg; 424 vb->stats_vq = vqs[2]; 425 426 /* 427 * Prime this virtqueue with one buffer so the hypervisor can 428 * use it to signal us later (it can't be broken yet!). 429 */ 430 sg_init_one(&sg, vb->stats, sizeof vb->stats); 431 if (virtqueue_add_outbuf(vb->stats_vq, &sg, 1, vb, GFP_KERNEL) 432 < 0) 433 BUG(); 434 virtqueue_kick(vb->stats_vq); 435 } 436 return 0; 437 } 438 439 #ifdef CONFIG_BALLOON_COMPACTION 440 /* 441 * virtballoon_migratepage - perform the balloon page migration on behalf of 442 * a compation thread. (called under page lock) 443 * @vb_dev_info: the balloon device 444 * @newpage: page that will replace the isolated page after migration finishes. 445 * @page : the isolated (old) page that is about to be migrated to newpage. 446 * @mode : compaction mode -- not used for balloon page migration. 447 * 448 * After a ballooned page gets isolated by compaction procedures, this is the 449 * function that performs the page migration on behalf of a compaction thread 450 * The page migration for virtio balloon is done in a simple swap fashion which 451 * follows these two macro steps: 452 * 1) insert newpage into vb->pages list and update the host about it; 453 * 2) update the host about the old page removed from vb->pages list; 454 * 455 * This function preforms the balloon page migration task. 456 * Called through balloon_mapping->a_ops->migratepage 457 */ 458 static int virtballoon_migratepage(struct balloon_dev_info *vb_dev_info, 459 struct page *newpage, struct page *page, enum migrate_mode mode) 460 { 461 struct virtio_balloon *vb = container_of(vb_dev_info, 462 struct virtio_balloon, vb_dev_info); 463 unsigned long flags; 464 465 /* 466 * In order to avoid lock contention while migrating pages concurrently 467 * to leak_balloon() or fill_balloon() we just give up the balloon_lock 468 * this turn, as it is easier to retry the page migration later. 469 * This also prevents fill_balloon() getting stuck into a mutex 470 * recursion in the case it ends up triggering memory compaction 471 * while it is attempting to inflate the ballon. 472 */ 473 if (!mutex_trylock(&vb->balloon_lock)) 474 return -EAGAIN; 475 476 get_page(newpage); /* balloon reference */ 477 478 /* balloon's page migration 1st step -- inflate "newpage" */ 479 spin_lock_irqsave(&vb_dev_info->pages_lock, flags); 480 balloon_page_insert(vb_dev_info, newpage); 481 vb_dev_info->isolated_pages--; 482 __count_vm_event(BALLOON_MIGRATE); 483 spin_unlock_irqrestore(&vb_dev_info->pages_lock, flags); 484 vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE; 485 set_page_pfns(vb, vb->pfns, newpage); 486 tell_host(vb, vb->inflate_vq); 487 488 /* balloon's page migration 2nd step -- deflate "page" */ 489 balloon_page_delete(page); 490 vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE; 491 set_page_pfns(vb, vb->pfns, page); 492 tell_host(vb, vb->deflate_vq); 493 494 mutex_unlock(&vb->balloon_lock); 495 496 put_page(page); /* balloon reference */ 497 498 return MIGRATEPAGE_SUCCESS; 499 } 500 501 static struct dentry *balloon_mount(struct file_system_type *fs_type, 502 int flags, const char *dev_name, void *data) 503 { 504 static const struct dentry_operations ops = { 505 .d_dname = simple_dname, 506 }; 507 508 return mount_pseudo(fs_type, "balloon-kvm:", NULL, &ops, 509 BALLOON_KVM_MAGIC); 510 } 511 512 static struct file_system_type balloon_fs = { 513 .name = "balloon-kvm", 514 .mount = balloon_mount, 515 .kill_sb = kill_anon_super, 516 }; 517 518 #endif /* CONFIG_BALLOON_COMPACTION */ 519 520 static int virtballoon_probe(struct virtio_device *vdev) 521 { 522 struct virtio_balloon *vb; 523 int err; 524 525 if (!vdev->config->get) { 526 dev_err(&vdev->dev, "%s failure: config access disabled\n", 527 __func__); 528 return -EINVAL; 529 } 530 531 vdev->priv = vb = kmalloc(sizeof(*vb), GFP_KERNEL); 532 if (!vb) { 533 err = -ENOMEM; 534 goto out; 535 } 536 537 INIT_WORK(&vb->update_balloon_stats_work, update_balloon_stats_func); 538 INIT_WORK(&vb->update_balloon_size_work, update_balloon_size_func); 539 spin_lock_init(&vb->stop_update_lock); 540 vb->stop_update = false; 541 vb->num_pages = 0; 542 mutex_init(&vb->balloon_lock); 543 init_waitqueue_head(&vb->acked); 544 vb->vdev = vdev; 545 546 balloon_devinfo_init(&vb->vb_dev_info); 547 548 err = init_vqs(vb); 549 if (err) 550 goto out_free_vb; 551 552 vb->nb.notifier_call = virtballoon_oom_notify; 553 vb->nb.priority = VIRTBALLOON_OOM_NOTIFY_PRIORITY; 554 err = register_oom_notifier(&vb->nb); 555 if (err < 0) 556 goto out_del_vqs; 557 558 #ifdef CONFIG_BALLOON_COMPACTION 559 balloon_mnt = kern_mount(&balloon_fs); 560 if (IS_ERR(balloon_mnt)) { 561 err = PTR_ERR(balloon_mnt); 562 unregister_oom_notifier(&vb->nb); 563 goto out_del_vqs; 564 } 565 566 vb->vb_dev_info.migratepage = virtballoon_migratepage; 567 vb->vb_dev_info.inode = alloc_anon_inode(balloon_mnt->mnt_sb); 568 if (IS_ERR(vb->vb_dev_info.inode)) { 569 err = PTR_ERR(vb->vb_dev_info.inode); 570 kern_unmount(balloon_mnt); 571 unregister_oom_notifier(&vb->nb); 572 vb->vb_dev_info.inode = NULL; 573 goto out_del_vqs; 574 } 575 vb->vb_dev_info.inode->i_mapping->a_ops = &balloon_aops; 576 #endif 577 578 virtio_device_ready(vdev); 579 580 if (towards_target(vb)) 581 virtballoon_changed(vdev); 582 return 0; 583 584 out_del_vqs: 585 vdev->config->del_vqs(vdev); 586 out_free_vb: 587 kfree(vb); 588 out: 589 return err; 590 } 591 592 static void remove_common(struct virtio_balloon *vb) 593 { 594 /* There might be pages left in the balloon: free them. */ 595 while (vb->num_pages) 596 leak_balloon(vb, vb->num_pages); 597 update_balloon_size(vb); 598 599 /* Now we reset the device so we can clean up the queues. */ 600 vb->vdev->config->reset(vb->vdev); 601 602 vb->vdev->config->del_vqs(vb->vdev); 603 } 604 605 static void virtballoon_remove(struct virtio_device *vdev) 606 { 607 struct virtio_balloon *vb = vdev->priv; 608 609 unregister_oom_notifier(&vb->nb); 610 611 spin_lock_irq(&vb->stop_update_lock); 612 vb->stop_update = true; 613 spin_unlock_irq(&vb->stop_update_lock); 614 cancel_work_sync(&vb->update_balloon_size_work); 615 cancel_work_sync(&vb->update_balloon_stats_work); 616 617 remove_common(vb); 618 #ifdef CONFIG_BALLOON_COMPACTION 619 if (vb->vb_dev_info.inode) 620 iput(vb->vb_dev_info.inode); 621 622 kern_unmount(balloon_mnt); 623 #endif 624 kfree(vb); 625 } 626 627 #ifdef CONFIG_PM_SLEEP 628 static int virtballoon_freeze(struct virtio_device *vdev) 629 { 630 struct virtio_balloon *vb = vdev->priv; 631 632 /* 633 * The workqueue is already frozen by the PM core before this 634 * function is called. 635 */ 636 remove_common(vb); 637 return 0; 638 } 639 640 static int virtballoon_restore(struct virtio_device *vdev) 641 { 642 struct virtio_balloon *vb = vdev->priv; 643 int ret; 644 645 ret = init_vqs(vdev->priv); 646 if (ret) 647 return ret; 648 649 virtio_device_ready(vdev); 650 651 if (towards_target(vb)) 652 virtballoon_changed(vdev); 653 update_balloon_size(vb); 654 return 0; 655 } 656 #endif 657 658 static unsigned int features[] = { 659 VIRTIO_BALLOON_F_MUST_TELL_HOST, 660 VIRTIO_BALLOON_F_STATS_VQ, 661 VIRTIO_BALLOON_F_DEFLATE_ON_OOM, 662 }; 663 664 static struct virtio_driver virtio_balloon_driver = { 665 .feature_table = features, 666 .feature_table_size = ARRAY_SIZE(features), 667 .driver.name = KBUILD_MODNAME, 668 .driver.owner = THIS_MODULE, 669 .id_table = id_table, 670 .probe = virtballoon_probe, 671 .remove = virtballoon_remove, 672 .config_changed = virtballoon_changed, 673 #ifdef CONFIG_PM_SLEEP 674 .freeze = virtballoon_freeze, 675 .restore = virtballoon_restore, 676 #endif 677 }; 678 679 module_virtio_driver(virtio_balloon_driver); 680 MODULE_DEVICE_TABLE(virtio, id_table); 681 MODULE_DESCRIPTION("Virtio balloon driver"); 682 MODULE_LICENSE("GPL"); 683