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 #include <linux/magic.h> 35 36 /* 37 * Balloon device works in 4K page units. So each page is pointed to by 38 * multiple balloon pages. All memory counters in this driver are in balloon 39 * page units. 40 */ 41 #define VIRTIO_BALLOON_PAGES_PER_PAGE (unsigned)(PAGE_SIZE >> VIRTIO_BALLOON_PFN_SHIFT) 42 #define VIRTIO_BALLOON_ARRAY_PFNS_MAX 256 43 #define OOM_VBALLOON_DEFAULT_PAGES 256 44 #define VIRTBALLOON_OOM_NOTIFY_PRIORITY 80 45 46 static int oom_pages = OOM_VBALLOON_DEFAULT_PAGES; 47 module_param(oom_pages, int, S_IRUSR | S_IWUSR); 48 MODULE_PARM_DESC(oom_pages, "pages to free on OOM"); 49 50 #ifdef CONFIG_BALLOON_COMPACTION 51 static struct vfsmount *balloon_mnt; 52 #endif 53 54 struct virtio_balloon { 55 struct virtio_device *vdev; 56 struct virtqueue *inflate_vq, *deflate_vq, *stats_vq; 57 58 /* The balloon servicing is delegated to a freezable workqueue. */ 59 struct work_struct update_balloon_stats_work; 60 struct work_struct update_balloon_size_work; 61 62 /* Prevent updating balloon when it is being canceled. */ 63 spinlock_t stop_update_lock; 64 bool stop_update; 65 66 /* Waiting for host to ack the pages we released. */ 67 wait_queue_head_t acked; 68 69 /* Number of balloon pages we've told the Host we're not using. */ 70 unsigned int num_pages; 71 /* 72 * The pages we've told the Host we're not using are enqueued 73 * at vb_dev_info->pages list. 74 * Each page on this list adds VIRTIO_BALLOON_PAGES_PER_PAGE 75 * to num_pages above. 76 */ 77 struct balloon_dev_info vb_dev_info; 78 79 /* Synchronize access/update to this struct virtio_balloon elements */ 80 struct mutex balloon_lock; 81 82 /* The array of pfns we tell the Host about. */ 83 unsigned int num_pfns; 84 __virtio32 pfns[VIRTIO_BALLOON_ARRAY_PFNS_MAX]; 85 86 /* Memory statistics */ 87 struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR]; 88 89 /* To register callback in oom notifier call chain */ 90 struct notifier_block nb; 91 }; 92 93 static struct virtio_device_id id_table[] = { 94 { VIRTIO_ID_BALLOON, VIRTIO_DEV_ANY_ID }, 95 { 0 }, 96 }; 97 98 static u32 page_to_balloon_pfn(struct page *page) 99 { 100 unsigned long pfn = page_to_pfn(page); 101 102 BUILD_BUG_ON(PAGE_SHIFT < VIRTIO_BALLOON_PFN_SHIFT); 103 /* Convert pfn from Linux page size to balloon page size. */ 104 return pfn * VIRTIO_BALLOON_PAGES_PER_PAGE; 105 } 106 107 static void balloon_ack(struct virtqueue *vq) 108 { 109 struct virtio_balloon *vb = vq->vdev->priv; 110 111 wake_up(&vb->acked); 112 } 113 114 static void tell_host(struct virtio_balloon *vb, struct virtqueue *vq) 115 { 116 struct scatterlist sg; 117 unsigned int len; 118 119 sg_init_one(&sg, vb->pfns, sizeof(vb->pfns[0]) * vb->num_pfns); 120 121 /* We should always be able to add one buffer to an empty queue. */ 122 virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL); 123 virtqueue_kick(vq); 124 125 /* When host has read buffer, this completes via balloon_ack */ 126 wait_event(vb->acked, virtqueue_get_buf(vq, &len)); 127 128 } 129 130 static void set_page_pfns(struct virtio_balloon *vb, 131 __virtio32 pfns[], struct page *page) 132 { 133 unsigned int i; 134 135 /* 136 * Set balloon pfns pointing at this page. 137 * Note that the first pfn points at start of the page. 138 */ 139 for (i = 0; i < VIRTIO_BALLOON_PAGES_PER_PAGE; i++) 140 pfns[i] = cpu_to_virtio32(vb->vdev, 141 page_to_balloon_pfn(page) + i); 142 } 143 144 static unsigned fill_balloon(struct virtio_balloon *vb, size_t num) 145 { 146 struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info; 147 unsigned num_allocated_pages; 148 149 /* We can only do one array worth at a time. */ 150 num = min(num, ARRAY_SIZE(vb->pfns)); 151 152 mutex_lock(&vb->balloon_lock); 153 for (vb->num_pfns = 0; vb->num_pfns < num; 154 vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) { 155 struct page *page = balloon_page_enqueue(vb_dev_info); 156 157 if (!page) { 158 dev_info_ratelimited(&vb->vdev->dev, 159 "Out of puff! Can't get %u pages\n", 160 VIRTIO_BALLOON_PAGES_PER_PAGE); 161 /* Sleep for at least 1/5 of a second before retry. */ 162 msleep(200); 163 break; 164 } 165 set_page_pfns(vb, vb->pfns + vb->num_pfns, page); 166 vb->num_pages += VIRTIO_BALLOON_PAGES_PER_PAGE; 167 if (!virtio_has_feature(vb->vdev, 168 VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) 169 adjust_managed_page_count(page, -1); 170 } 171 172 num_allocated_pages = vb->num_pfns; 173 /* Did we get any? */ 174 if (vb->num_pfns != 0) 175 tell_host(vb, vb->inflate_vq); 176 mutex_unlock(&vb->balloon_lock); 177 178 return num_allocated_pages; 179 } 180 181 static void release_pages_balloon(struct virtio_balloon *vb, 182 struct list_head *pages) 183 { 184 struct page *page, *next; 185 186 list_for_each_entry_safe(page, next, pages, lru) { 187 if (!virtio_has_feature(vb->vdev, 188 VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) 189 adjust_managed_page_count(page, 1); 190 list_del(&page->lru); 191 put_page(page); /* balloon reference */ 192 } 193 } 194 195 static unsigned leak_balloon(struct virtio_balloon *vb, size_t num) 196 { 197 unsigned num_freed_pages; 198 struct page *page; 199 struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info; 200 LIST_HEAD(pages); 201 202 /* We can only do one array worth at a time. */ 203 num = min(num, ARRAY_SIZE(vb->pfns)); 204 205 mutex_lock(&vb->balloon_lock); 206 /* We can't release more pages than taken */ 207 num = min(num, (size_t)vb->num_pages); 208 for (vb->num_pfns = 0; vb->num_pfns < num; 209 vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) { 210 page = balloon_page_dequeue(vb_dev_info); 211 if (!page) 212 break; 213 set_page_pfns(vb, vb->pfns + vb->num_pfns, page); 214 list_add(&page->lru, &pages); 215 vb->num_pages -= VIRTIO_BALLOON_PAGES_PER_PAGE; 216 } 217 218 num_freed_pages = vb->num_pfns; 219 /* 220 * Note that if 221 * virtio_has_feature(vdev, VIRTIO_BALLOON_F_MUST_TELL_HOST); 222 * is true, we *have* to do it in this order 223 */ 224 if (vb->num_pfns != 0) 225 tell_host(vb, vb->deflate_vq); 226 release_pages_balloon(vb, &pages); 227 mutex_unlock(&vb->balloon_lock); 228 return num_freed_pages; 229 } 230 231 static inline void update_stat(struct virtio_balloon *vb, int idx, 232 u16 tag, u64 val) 233 { 234 BUG_ON(idx >= VIRTIO_BALLOON_S_NR); 235 vb->stats[idx].tag = cpu_to_virtio16(vb->vdev, tag); 236 vb->stats[idx].val = cpu_to_virtio64(vb->vdev, val); 237 } 238 239 #define pages_to_bytes(x) ((u64)(x) << PAGE_SHIFT) 240 241 static unsigned int update_balloon_stats(struct virtio_balloon *vb) 242 { 243 unsigned long events[NR_VM_EVENT_ITEMS]; 244 struct sysinfo i; 245 unsigned int idx = 0; 246 long available; 247 248 all_vm_events(events); 249 si_meminfo(&i); 250 251 available = si_mem_available(); 252 253 #ifdef CONFIG_VM_EVENT_COUNTERS 254 update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_IN, 255 pages_to_bytes(events[PSWPIN])); 256 update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_OUT, 257 pages_to_bytes(events[PSWPOUT])); 258 update_stat(vb, idx++, VIRTIO_BALLOON_S_MAJFLT, events[PGMAJFAULT]); 259 update_stat(vb, idx++, VIRTIO_BALLOON_S_MINFLT, events[PGFAULT]); 260 #endif 261 update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMFREE, 262 pages_to_bytes(i.freeram)); 263 update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMTOT, 264 pages_to_bytes(i.totalram)); 265 update_stat(vb, idx++, VIRTIO_BALLOON_S_AVAIL, 266 pages_to_bytes(available)); 267 268 return idx; 269 } 270 271 /* 272 * While most virtqueues communicate guest-initiated requests to the hypervisor, 273 * the stats queue operates in reverse. The driver initializes the virtqueue 274 * with a single buffer. From that point forward, all conversations consist of 275 * a hypervisor request (a call to this function) which directs us to refill 276 * the virtqueue with a fresh stats buffer. Since stats collection can sleep, 277 * we delegate the job to a freezable workqueue that will do the actual work via 278 * stats_handle_request(). 279 */ 280 static void stats_request(struct virtqueue *vq) 281 { 282 struct virtio_balloon *vb = vq->vdev->priv; 283 284 spin_lock(&vb->stop_update_lock); 285 if (!vb->stop_update) 286 queue_work(system_freezable_wq, &vb->update_balloon_stats_work); 287 spin_unlock(&vb->stop_update_lock); 288 } 289 290 static void stats_handle_request(struct virtio_balloon *vb) 291 { 292 struct virtqueue *vq; 293 struct scatterlist sg; 294 unsigned int len, num_stats; 295 296 num_stats = update_balloon_stats(vb); 297 298 vq = vb->stats_vq; 299 if (!virtqueue_get_buf(vq, &len)) 300 return; 301 sg_init_one(&sg, vb->stats, sizeof(vb->stats[0]) * num_stats); 302 virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL); 303 virtqueue_kick(vq); 304 } 305 306 static void virtballoon_changed(struct virtio_device *vdev) 307 { 308 struct virtio_balloon *vb = vdev->priv; 309 unsigned long flags; 310 311 spin_lock_irqsave(&vb->stop_update_lock, flags); 312 if (!vb->stop_update) 313 queue_work(system_freezable_wq, &vb->update_balloon_size_work); 314 spin_unlock_irqrestore(&vb->stop_update_lock, flags); 315 } 316 317 static inline s64 towards_target(struct virtio_balloon *vb) 318 { 319 s64 target; 320 u32 num_pages; 321 322 virtio_cread(vb->vdev, struct virtio_balloon_config, num_pages, 323 &num_pages); 324 325 /* Legacy balloon config space is LE, unlike all other devices. */ 326 if (!virtio_has_feature(vb->vdev, VIRTIO_F_VERSION_1)) 327 num_pages = le32_to_cpu((__force __le32)num_pages); 328 329 target = num_pages; 330 return target - vb->num_pages; 331 } 332 333 static void update_balloon_size(struct virtio_balloon *vb) 334 { 335 u32 actual = vb->num_pages; 336 337 /* Legacy balloon config space is LE, unlike all other devices. */ 338 if (!virtio_has_feature(vb->vdev, VIRTIO_F_VERSION_1)) 339 actual = (__force u32)cpu_to_le32(actual); 340 341 virtio_cwrite(vb->vdev, struct virtio_balloon_config, actual, 342 &actual); 343 } 344 345 /* 346 * virtballoon_oom_notify - release pages when system is under severe 347 * memory pressure (called from out_of_memory()) 348 * @self : notifier block struct 349 * @dummy: not used 350 * @parm : returned - number of freed pages 351 * 352 * The balancing of memory by use of the virtio balloon should not cause 353 * the termination of processes while there are pages in the balloon. 354 * If virtio balloon manages to release some memory, it will make the 355 * system return and retry the allocation that forced the OOM killer 356 * to run. 357 */ 358 static int virtballoon_oom_notify(struct notifier_block *self, 359 unsigned long dummy, void *parm) 360 { 361 struct virtio_balloon *vb; 362 unsigned long *freed; 363 unsigned num_freed_pages; 364 365 vb = container_of(self, struct virtio_balloon, nb); 366 if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) 367 return NOTIFY_OK; 368 369 freed = parm; 370 num_freed_pages = leak_balloon(vb, oom_pages); 371 update_balloon_size(vb); 372 *freed += num_freed_pages; 373 374 return NOTIFY_OK; 375 } 376 377 static void update_balloon_stats_func(struct work_struct *work) 378 { 379 struct virtio_balloon *vb; 380 381 vb = container_of(work, struct virtio_balloon, 382 update_balloon_stats_work); 383 stats_handle_request(vb); 384 } 385 386 static void update_balloon_size_func(struct work_struct *work) 387 { 388 struct virtio_balloon *vb; 389 s64 diff; 390 391 vb = container_of(work, struct virtio_balloon, 392 update_balloon_size_work); 393 diff = towards_target(vb); 394 395 if (diff > 0) 396 diff -= fill_balloon(vb, diff); 397 else if (diff < 0) 398 diff += leak_balloon(vb, -diff); 399 update_balloon_size(vb); 400 401 if (diff) 402 queue_work(system_freezable_wq, work); 403 } 404 405 static int init_vqs(struct virtio_balloon *vb) 406 { 407 struct virtqueue *vqs[3]; 408 vq_callback_t *callbacks[] = { balloon_ack, balloon_ack, stats_request }; 409 static const char * const names[] = { "inflate", "deflate", "stats" }; 410 int err, nvqs; 411 412 /* 413 * We expect two virtqueues: inflate and deflate, and 414 * optionally stat. 415 */ 416 nvqs = virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ) ? 3 : 2; 417 err = virtio_find_vqs(vb->vdev, nvqs, vqs, callbacks, names, NULL); 418 if (err) 419 return err; 420 421 vb->inflate_vq = vqs[0]; 422 vb->deflate_vq = vqs[1]; 423 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) { 424 struct scatterlist sg; 425 unsigned int num_stats; 426 vb->stats_vq = vqs[2]; 427 428 /* 429 * Prime this virtqueue with one buffer so the hypervisor can 430 * use it to signal us later (it can't be broken yet!). 431 */ 432 num_stats = update_balloon_stats(vb); 433 434 sg_init_one(&sg, vb->stats, sizeof(vb->stats[0]) * num_stats); 435 if (virtqueue_add_outbuf(vb->stats_vq, &sg, 1, vb, GFP_KERNEL) 436 < 0) 437 BUG(); 438 virtqueue_kick(vb->stats_vq); 439 } 440 return 0; 441 } 442 443 #ifdef CONFIG_BALLOON_COMPACTION 444 /* 445 * virtballoon_migratepage - perform the balloon page migration on behalf of 446 * a compation thread. (called under page lock) 447 * @vb_dev_info: the balloon device 448 * @newpage: page that will replace the isolated page after migration finishes. 449 * @page : the isolated (old) page that is about to be migrated to newpage. 450 * @mode : compaction mode -- not used for balloon page migration. 451 * 452 * After a ballooned page gets isolated by compaction procedures, this is the 453 * function that performs the page migration on behalf of a compaction thread 454 * The page migration for virtio balloon is done in a simple swap fashion which 455 * follows these two macro steps: 456 * 1) insert newpage into vb->pages list and update the host about it; 457 * 2) update the host about the old page removed from vb->pages list; 458 * 459 * This function preforms the balloon page migration task. 460 * Called through balloon_mapping->a_ops->migratepage 461 */ 462 static int virtballoon_migratepage(struct balloon_dev_info *vb_dev_info, 463 struct page *newpage, struct page *page, enum migrate_mode mode) 464 { 465 struct virtio_balloon *vb = container_of(vb_dev_info, 466 struct virtio_balloon, vb_dev_info); 467 unsigned long flags; 468 469 /* 470 * In order to avoid lock contention while migrating pages concurrently 471 * to leak_balloon() or fill_balloon() we just give up the balloon_lock 472 * this turn, as it is easier to retry the page migration later. 473 * This also prevents fill_balloon() getting stuck into a mutex 474 * recursion in the case it ends up triggering memory compaction 475 * while it is attempting to inflate the ballon. 476 */ 477 if (!mutex_trylock(&vb->balloon_lock)) 478 return -EAGAIN; 479 480 get_page(newpage); /* balloon reference */ 481 482 /* balloon's page migration 1st step -- inflate "newpage" */ 483 spin_lock_irqsave(&vb_dev_info->pages_lock, flags); 484 balloon_page_insert(vb_dev_info, newpage); 485 vb_dev_info->isolated_pages--; 486 __count_vm_event(BALLOON_MIGRATE); 487 spin_unlock_irqrestore(&vb_dev_info->pages_lock, flags); 488 vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE; 489 set_page_pfns(vb, vb->pfns, newpage); 490 tell_host(vb, vb->inflate_vq); 491 492 /* balloon's page migration 2nd step -- deflate "page" */ 493 balloon_page_delete(page); 494 vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE; 495 set_page_pfns(vb, vb->pfns, page); 496 tell_host(vb, vb->deflate_vq); 497 498 mutex_unlock(&vb->balloon_lock); 499 500 put_page(page); /* balloon reference */ 501 502 return MIGRATEPAGE_SUCCESS; 503 } 504 505 static struct dentry *balloon_mount(struct file_system_type *fs_type, 506 int flags, const char *dev_name, void *data) 507 { 508 static const struct dentry_operations ops = { 509 .d_dname = simple_dname, 510 }; 511 512 return mount_pseudo(fs_type, "balloon-kvm:", NULL, &ops, 513 BALLOON_KVM_MAGIC); 514 } 515 516 static struct file_system_type balloon_fs = { 517 .name = "balloon-kvm", 518 .mount = balloon_mount, 519 .kill_sb = kill_anon_super, 520 }; 521 522 #endif /* CONFIG_BALLOON_COMPACTION */ 523 524 static int virtballoon_probe(struct virtio_device *vdev) 525 { 526 struct virtio_balloon *vb; 527 int err; 528 529 if (!vdev->config->get) { 530 dev_err(&vdev->dev, "%s failure: config access disabled\n", 531 __func__); 532 return -EINVAL; 533 } 534 535 vdev->priv = vb = kmalloc(sizeof(*vb), GFP_KERNEL); 536 if (!vb) { 537 err = -ENOMEM; 538 goto out; 539 } 540 541 INIT_WORK(&vb->update_balloon_stats_work, update_balloon_stats_func); 542 INIT_WORK(&vb->update_balloon_size_work, update_balloon_size_func); 543 spin_lock_init(&vb->stop_update_lock); 544 vb->stop_update = false; 545 vb->num_pages = 0; 546 mutex_init(&vb->balloon_lock); 547 init_waitqueue_head(&vb->acked); 548 vb->vdev = vdev; 549 550 balloon_devinfo_init(&vb->vb_dev_info); 551 552 err = init_vqs(vb); 553 if (err) 554 goto out_free_vb; 555 556 vb->nb.notifier_call = virtballoon_oom_notify; 557 vb->nb.priority = VIRTBALLOON_OOM_NOTIFY_PRIORITY; 558 err = register_oom_notifier(&vb->nb); 559 if (err < 0) 560 goto out_del_vqs; 561 562 #ifdef CONFIG_BALLOON_COMPACTION 563 balloon_mnt = kern_mount(&balloon_fs); 564 if (IS_ERR(balloon_mnt)) { 565 err = PTR_ERR(balloon_mnt); 566 unregister_oom_notifier(&vb->nb); 567 goto out_del_vqs; 568 } 569 570 vb->vb_dev_info.migratepage = virtballoon_migratepage; 571 vb->vb_dev_info.inode = alloc_anon_inode(balloon_mnt->mnt_sb); 572 if (IS_ERR(vb->vb_dev_info.inode)) { 573 err = PTR_ERR(vb->vb_dev_info.inode); 574 kern_unmount(balloon_mnt); 575 unregister_oom_notifier(&vb->nb); 576 vb->vb_dev_info.inode = NULL; 577 goto out_del_vqs; 578 } 579 vb->vb_dev_info.inode->i_mapping->a_ops = &balloon_aops; 580 #endif 581 582 virtio_device_ready(vdev); 583 584 if (towards_target(vb)) 585 virtballoon_changed(vdev); 586 return 0; 587 588 out_del_vqs: 589 vdev->config->del_vqs(vdev); 590 out_free_vb: 591 kfree(vb); 592 out: 593 return err; 594 } 595 596 static void remove_common(struct virtio_balloon *vb) 597 { 598 /* There might be pages left in the balloon: free them. */ 599 while (vb->num_pages) 600 leak_balloon(vb, vb->num_pages); 601 update_balloon_size(vb); 602 603 /* Now we reset the device so we can clean up the queues. */ 604 vb->vdev->config->reset(vb->vdev); 605 606 vb->vdev->config->del_vqs(vb->vdev); 607 } 608 609 static void virtballoon_remove(struct virtio_device *vdev) 610 { 611 struct virtio_balloon *vb = vdev->priv; 612 613 unregister_oom_notifier(&vb->nb); 614 615 spin_lock_irq(&vb->stop_update_lock); 616 vb->stop_update = true; 617 spin_unlock_irq(&vb->stop_update_lock); 618 cancel_work_sync(&vb->update_balloon_size_work); 619 cancel_work_sync(&vb->update_balloon_stats_work); 620 621 remove_common(vb); 622 #ifdef CONFIG_BALLOON_COMPACTION 623 if (vb->vb_dev_info.inode) 624 iput(vb->vb_dev_info.inode); 625 626 kern_unmount(balloon_mnt); 627 #endif 628 kfree(vb); 629 } 630 631 #ifdef CONFIG_PM_SLEEP 632 static int virtballoon_freeze(struct virtio_device *vdev) 633 { 634 struct virtio_balloon *vb = vdev->priv; 635 636 /* 637 * The workqueue is already frozen by the PM core before this 638 * function is called. 639 */ 640 remove_common(vb); 641 return 0; 642 } 643 644 static int virtballoon_restore(struct virtio_device *vdev) 645 { 646 struct virtio_balloon *vb = vdev->priv; 647 int ret; 648 649 ret = init_vqs(vdev->priv); 650 if (ret) 651 return ret; 652 653 virtio_device_ready(vdev); 654 655 if (towards_target(vb)) 656 virtballoon_changed(vdev); 657 update_balloon_size(vb); 658 return 0; 659 } 660 #endif 661 662 static int virtballoon_validate(struct virtio_device *vdev) 663 { 664 __virtio_clear_bit(vdev, VIRTIO_F_IOMMU_PLATFORM); 665 return 0; 666 } 667 668 static unsigned int features[] = { 669 VIRTIO_BALLOON_F_MUST_TELL_HOST, 670 VIRTIO_BALLOON_F_STATS_VQ, 671 VIRTIO_BALLOON_F_DEFLATE_ON_OOM, 672 }; 673 674 static struct virtio_driver virtio_balloon_driver = { 675 .feature_table = features, 676 .feature_table_size = ARRAY_SIZE(features), 677 .driver.name = KBUILD_MODNAME, 678 .driver.owner = THIS_MODULE, 679 .id_table = id_table, 680 .validate = virtballoon_validate, 681 .probe = virtballoon_probe, 682 .remove = virtballoon_remove, 683 .config_changed = virtballoon_changed, 684 #ifdef CONFIG_PM_SLEEP 685 .freeze = virtballoon_freeze, 686 .restore = virtballoon_restore, 687 #endif 688 }; 689 690 module_virtio_driver(virtio_balloon_driver); 691 MODULE_DEVICE_TABLE(virtio, id_table); 692 MODULE_DESCRIPTION("Virtio balloon driver"); 693 MODULE_LICENSE("GPL"); 694