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 unsigned num_allocated_pages; 147 unsigned num_pfns; 148 struct page *page; 149 LIST_HEAD(pages); 150 151 /* We can only do one array worth at a time. */ 152 num = min(num, ARRAY_SIZE(vb->pfns)); 153 154 for (num_pfns = 0; num_pfns < num; 155 num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) { 156 struct page *page = balloon_page_alloc(); 157 158 if (!page) { 159 dev_info_ratelimited(&vb->vdev->dev, 160 "Out of puff! Can't get %u pages\n", 161 VIRTIO_BALLOON_PAGES_PER_PAGE); 162 /* Sleep for at least 1/5 of a second before retry. */ 163 msleep(200); 164 break; 165 } 166 167 balloon_page_push(&pages, page); 168 } 169 170 mutex_lock(&vb->balloon_lock); 171 172 vb->num_pfns = 0; 173 174 while ((page = balloon_page_pop(&pages))) { 175 balloon_page_enqueue(&vb->vb_dev_info, page); 176 177 vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE; 178 179 set_page_pfns(vb, vb->pfns + vb->num_pfns, page); 180 vb->num_pages += VIRTIO_BALLOON_PAGES_PER_PAGE; 181 if (!virtio_has_feature(vb->vdev, 182 VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) 183 adjust_managed_page_count(page, -1); 184 } 185 186 num_allocated_pages = vb->num_pfns; 187 /* Did we get any? */ 188 if (vb->num_pfns != 0) 189 tell_host(vb, vb->inflate_vq); 190 mutex_unlock(&vb->balloon_lock); 191 192 return num_allocated_pages; 193 } 194 195 static void release_pages_balloon(struct virtio_balloon *vb, 196 struct list_head *pages) 197 { 198 struct page *page, *next; 199 200 list_for_each_entry_safe(page, next, pages, lru) { 201 if (!virtio_has_feature(vb->vdev, 202 VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) 203 adjust_managed_page_count(page, 1); 204 list_del(&page->lru); 205 put_page(page); /* balloon reference */ 206 } 207 } 208 209 static unsigned leak_balloon(struct virtio_balloon *vb, size_t num) 210 { 211 unsigned num_freed_pages; 212 struct page *page; 213 struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info; 214 LIST_HEAD(pages); 215 216 /* We can only do one array worth at a time. */ 217 num = min(num, ARRAY_SIZE(vb->pfns)); 218 219 mutex_lock(&vb->balloon_lock); 220 /* We can't release more pages than taken */ 221 num = min(num, (size_t)vb->num_pages); 222 for (vb->num_pfns = 0; vb->num_pfns < num; 223 vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) { 224 page = balloon_page_dequeue(vb_dev_info); 225 if (!page) 226 break; 227 set_page_pfns(vb, vb->pfns + vb->num_pfns, page); 228 list_add(&page->lru, &pages); 229 vb->num_pages -= VIRTIO_BALLOON_PAGES_PER_PAGE; 230 } 231 232 num_freed_pages = vb->num_pfns; 233 /* 234 * Note that if 235 * virtio_has_feature(vdev, VIRTIO_BALLOON_F_MUST_TELL_HOST); 236 * is true, we *have* to do it in this order 237 */ 238 if (vb->num_pfns != 0) 239 tell_host(vb, vb->deflate_vq); 240 release_pages_balloon(vb, &pages); 241 mutex_unlock(&vb->balloon_lock); 242 return num_freed_pages; 243 } 244 245 static inline void update_stat(struct virtio_balloon *vb, int idx, 246 u16 tag, u64 val) 247 { 248 BUG_ON(idx >= VIRTIO_BALLOON_S_NR); 249 vb->stats[idx].tag = cpu_to_virtio16(vb->vdev, tag); 250 vb->stats[idx].val = cpu_to_virtio64(vb->vdev, val); 251 } 252 253 #define pages_to_bytes(x) ((u64)(x) << PAGE_SHIFT) 254 255 static unsigned int update_balloon_stats(struct virtio_balloon *vb) 256 { 257 unsigned long events[NR_VM_EVENT_ITEMS]; 258 struct sysinfo i; 259 unsigned int idx = 0; 260 long available; 261 262 all_vm_events(events); 263 si_meminfo(&i); 264 265 available = si_mem_available(); 266 267 #ifdef CONFIG_VM_EVENT_COUNTERS 268 update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_IN, 269 pages_to_bytes(events[PSWPIN])); 270 update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_OUT, 271 pages_to_bytes(events[PSWPOUT])); 272 update_stat(vb, idx++, VIRTIO_BALLOON_S_MAJFLT, events[PGMAJFAULT]); 273 update_stat(vb, idx++, VIRTIO_BALLOON_S_MINFLT, events[PGFAULT]); 274 #endif 275 update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMFREE, 276 pages_to_bytes(i.freeram)); 277 update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMTOT, 278 pages_to_bytes(i.totalram)); 279 update_stat(vb, idx++, VIRTIO_BALLOON_S_AVAIL, 280 pages_to_bytes(available)); 281 282 return idx; 283 } 284 285 /* 286 * While most virtqueues communicate guest-initiated requests to the hypervisor, 287 * the stats queue operates in reverse. The driver initializes the virtqueue 288 * with a single buffer. From that point forward, all conversations consist of 289 * a hypervisor request (a call to this function) which directs us to refill 290 * the virtqueue with a fresh stats buffer. Since stats collection can sleep, 291 * we delegate the job to a freezable workqueue that will do the actual work via 292 * stats_handle_request(). 293 */ 294 static void stats_request(struct virtqueue *vq) 295 { 296 struct virtio_balloon *vb = vq->vdev->priv; 297 298 spin_lock(&vb->stop_update_lock); 299 if (!vb->stop_update) 300 queue_work(system_freezable_wq, &vb->update_balloon_stats_work); 301 spin_unlock(&vb->stop_update_lock); 302 } 303 304 static void stats_handle_request(struct virtio_balloon *vb) 305 { 306 struct virtqueue *vq; 307 struct scatterlist sg; 308 unsigned int len, num_stats; 309 310 num_stats = update_balloon_stats(vb); 311 312 vq = vb->stats_vq; 313 if (!virtqueue_get_buf(vq, &len)) 314 return; 315 sg_init_one(&sg, vb->stats, sizeof(vb->stats[0]) * num_stats); 316 virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL); 317 virtqueue_kick(vq); 318 } 319 320 static void virtballoon_changed(struct virtio_device *vdev) 321 { 322 struct virtio_balloon *vb = vdev->priv; 323 unsigned long flags; 324 325 spin_lock_irqsave(&vb->stop_update_lock, flags); 326 if (!vb->stop_update) 327 queue_work(system_freezable_wq, &vb->update_balloon_size_work); 328 spin_unlock_irqrestore(&vb->stop_update_lock, flags); 329 } 330 331 static inline s64 towards_target(struct virtio_balloon *vb) 332 { 333 s64 target; 334 u32 num_pages; 335 336 virtio_cread(vb->vdev, struct virtio_balloon_config, num_pages, 337 &num_pages); 338 339 /* Legacy balloon config space is LE, unlike all other devices. */ 340 if (!virtio_has_feature(vb->vdev, VIRTIO_F_VERSION_1)) 341 num_pages = le32_to_cpu((__force __le32)num_pages); 342 343 target = num_pages; 344 return target - vb->num_pages; 345 } 346 347 static void update_balloon_size(struct virtio_balloon *vb) 348 { 349 u32 actual = vb->num_pages; 350 351 /* Legacy balloon config space is LE, unlike all other devices. */ 352 if (!virtio_has_feature(vb->vdev, VIRTIO_F_VERSION_1)) 353 actual = (__force u32)cpu_to_le32(actual); 354 355 virtio_cwrite(vb->vdev, struct virtio_balloon_config, actual, 356 &actual); 357 } 358 359 /* 360 * virtballoon_oom_notify - release pages when system is under severe 361 * memory pressure (called from out_of_memory()) 362 * @self : notifier block struct 363 * @dummy: not used 364 * @parm : returned - number of freed pages 365 * 366 * The balancing of memory by use of the virtio balloon should not cause 367 * the termination of processes while there are pages in the balloon. 368 * If virtio balloon manages to release some memory, it will make the 369 * system return and retry the allocation that forced the OOM killer 370 * to run. 371 */ 372 static int virtballoon_oom_notify(struct notifier_block *self, 373 unsigned long dummy, void *parm) 374 { 375 struct virtio_balloon *vb; 376 unsigned long *freed; 377 unsigned num_freed_pages; 378 379 vb = container_of(self, struct virtio_balloon, nb); 380 if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) 381 return NOTIFY_OK; 382 383 freed = parm; 384 num_freed_pages = leak_balloon(vb, oom_pages); 385 update_balloon_size(vb); 386 *freed += num_freed_pages; 387 388 return NOTIFY_OK; 389 } 390 391 static void update_balloon_stats_func(struct work_struct *work) 392 { 393 struct virtio_balloon *vb; 394 395 vb = container_of(work, struct virtio_balloon, 396 update_balloon_stats_work); 397 stats_handle_request(vb); 398 } 399 400 static void update_balloon_size_func(struct work_struct *work) 401 { 402 struct virtio_balloon *vb; 403 s64 diff; 404 405 vb = container_of(work, struct virtio_balloon, 406 update_balloon_size_work); 407 diff = towards_target(vb); 408 409 if (diff > 0) 410 diff -= fill_balloon(vb, diff); 411 else if (diff < 0) 412 diff += leak_balloon(vb, -diff); 413 update_balloon_size(vb); 414 415 if (diff) 416 queue_work(system_freezable_wq, work); 417 } 418 419 static int init_vqs(struct virtio_balloon *vb) 420 { 421 struct virtqueue *vqs[3]; 422 vq_callback_t *callbacks[] = { balloon_ack, balloon_ack, stats_request }; 423 static const char * const names[] = { "inflate", "deflate", "stats" }; 424 int err, nvqs; 425 426 /* 427 * We expect two virtqueues: inflate and deflate, and 428 * optionally stat. 429 */ 430 nvqs = virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ) ? 3 : 2; 431 err = virtio_find_vqs(vb->vdev, nvqs, vqs, callbacks, names, NULL); 432 if (err) 433 return err; 434 435 vb->inflate_vq = vqs[0]; 436 vb->deflate_vq = vqs[1]; 437 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) { 438 struct scatterlist sg; 439 unsigned int num_stats; 440 vb->stats_vq = vqs[2]; 441 442 /* 443 * Prime this virtqueue with one buffer so the hypervisor can 444 * use it to signal us later (it can't be broken yet!). 445 */ 446 num_stats = update_balloon_stats(vb); 447 448 sg_init_one(&sg, vb->stats, sizeof(vb->stats[0]) * num_stats); 449 if (virtqueue_add_outbuf(vb->stats_vq, &sg, 1, vb, GFP_KERNEL) 450 < 0) 451 BUG(); 452 virtqueue_kick(vb->stats_vq); 453 } 454 return 0; 455 } 456 457 #ifdef CONFIG_BALLOON_COMPACTION 458 /* 459 * virtballoon_migratepage - perform the balloon page migration on behalf of 460 * a compation thread. (called under page lock) 461 * @vb_dev_info: the balloon device 462 * @newpage: page that will replace the isolated page after migration finishes. 463 * @page : the isolated (old) page that is about to be migrated to newpage. 464 * @mode : compaction mode -- not used for balloon page migration. 465 * 466 * After a ballooned page gets isolated by compaction procedures, this is the 467 * function that performs the page migration on behalf of a compaction thread 468 * The page migration for virtio balloon is done in a simple swap fashion which 469 * follows these two macro steps: 470 * 1) insert newpage into vb->pages list and update the host about it; 471 * 2) update the host about the old page removed from vb->pages list; 472 * 473 * This function preforms the balloon page migration task. 474 * Called through balloon_mapping->a_ops->migratepage 475 */ 476 static int virtballoon_migratepage(struct balloon_dev_info *vb_dev_info, 477 struct page *newpage, struct page *page, enum migrate_mode mode) 478 { 479 struct virtio_balloon *vb = container_of(vb_dev_info, 480 struct virtio_balloon, vb_dev_info); 481 unsigned long flags; 482 483 /* 484 * In order to avoid lock contention while migrating pages concurrently 485 * to leak_balloon() or fill_balloon() we just give up the balloon_lock 486 * this turn, as it is easier to retry the page migration later. 487 * This also prevents fill_balloon() getting stuck into a mutex 488 * recursion in the case it ends up triggering memory compaction 489 * while it is attempting to inflate the ballon. 490 */ 491 if (!mutex_trylock(&vb->balloon_lock)) 492 return -EAGAIN; 493 494 get_page(newpage); /* balloon reference */ 495 496 /* balloon's page migration 1st step -- inflate "newpage" */ 497 spin_lock_irqsave(&vb_dev_info->pages_lock, flags); 498 balloon_page_insert(vb_dev_info, newpage); 499 vb_dev_info->isolated_pages--; 500 __count_vm_event(BALLOON_MIGRATE); 501 spin_unlock_irqrestore(&vb_dev_info->pages_lock, flags); 502 vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE; 503 set_page_pfns(vb, vb->pfns, newpage); 504 tell_host(vb, vb->inflate_vq); 505 506 /* balloon's page migration 2nd step -- deflate "page" */ 507 balloon_page_delete(page); 508 vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE; 509 set_page_pfns(vb, vb->pfns, page); 510 tell_host(vb, vb->deflate_vq); 511 512 mutex_unlock(&vb->balloon_lock); 513 514 put_page(page); /* balloon reference */ 515 516 return MIGRATEPAGE_SUCCESS; 517 } 518 519 static struct dentry *balloon_mount(struct file_system_type *fs_type, 520 int flags, const char *dev_name, void *data) 521 { 522 static const struct dentry_operations ops = { 523 .d_dname = simple_dname, 524 }; 525 526 return mount_pseudo(fs_type, "balloon-kvm:", NULL, &ops, 527 BALLOON_KVM_MAGIC); 528 } 529 530 static struct file_system_type balloon_fs = { 531 .name = "balloon-kvm", 532 .mount = balloon_mount, 533 .kill_sb = kill_anon_super, 534 }; 535 536 #endif /* CONFIG_BALLOON_COMPACTION */ 537 538 static int virtballoon_probe(struct virtio_device *vdev) 539 { 540 struct virtio_balloon *vb; 541 int err; 542 543 if (!vdev->config->get) { 544 dev_err(&vdev->dev, "%s failure: config access disabled\n", 545 __func__); 546 return -EINVAL; 547 } 548 549 vdev->priv = vb = kmalloc(sizeof(*vb), GFP_KERNEL); 550 if (!vb) { 551 err = -ENOMEM; 552 goto out; 553 } 554 555 INIT_WORK(&vb->update_balloon_stats_work, update_balloon_stats_func); 556 INIT_WORK(&vb->update_balloon_size_work, update_balloon_size_func); 557 spin_lock_init(&vb->stop_update_lock); 558 vb->stop_update = false; 559 vb->num_pages = 0; 560 mutex_init(&vb->balloon_lock); 561 init_waitqueue_head(&vb->acked); 562 vb->vdev = vdev; 563 564 balloon_devinfo_init(&vb->vb_dev_info); 565 566 err = init_vqs(vb); 567 if (err) 568 goto out_free_vb; 569 570 vb->nb.notifier_call = virtballoon_oom_notify; 571 vb->nb.priority = VIRTBALLOON_OOM_NOTIFY_PRIORITY; 572 err = register_oom_notifier(&vb->nb); 573 if (err < 0) 574 goto out_del_vqs; 575 576 #ifdef CONFIG_BALLOON_COMPACTION 577 balloon_mnt = kern_mount(&balloon_fs); 578 if (IS_ERR(balloon_mnt)) { 579 err = PTR_ERR(balloon_mnt); 580 unregister_oom_notifier(&vb->nb); 581 goto out_del_vqs; 582 } 583 584 vb->vb_dev_info.migratepage = virtballoon_migratepage; 585 vb->vb_dev_info.inode = alloc_anon_inode(balloon_mnt->mnt_sb); 586 if (IS_ERR(vb->vb_dev_info.inode)) { 587 err = PTR_ERR(vb->vb_dev_info.inode); 588 kern_unmount(balloon_mnt); 589 unregister_oom_notifier(&vb->nb); 590 vb->vb_dev_info.inode = NULL; 591 goto out_del_vqs; 592 } 593 vb->vb_dev_info.inode->i_mapping->a_ops = &balloon_aops; 594 #endif 595 596 virtio_device_ready(vdev); 597 598 if (towards_target(vb)) 599 virtballoon_changed(vdev); 600 return 0; 601 602 out_del_vqs: 603 vdev->config->del_vqs(vdev); 604 out_free_vb: 605 kfree(vb); 606 out: 607 return err; 608 } 609 610 static void remove_common(struct virtio_balloon *vb) 611 { 612 /* There might be pages left in the balloon: free them. */ 613 while (vb->num_pages) 614 leak_balloon(vb, vb->num_pages); 615 update_balloon_size(vb); 616 617 /* Now we reset the device so we can clean up the queues. */ 618 vb->vdev->config->reset(vb->vdev); 619 620 vb->vdev->config->del_vqs(vb->vdev); 621 } 622 623 static void virtballoon_remove(struct virtio_device *vdev) 624 { 625 struct virtio_balloon *vb = vdev->priv; 626 627 unregister_oom_notifier(&vb->nb); 628 629 spin_lock_irq(&vb->stop_update_lock); 630 vb->stop_update = true; 631 spin_unlock_irq(&vb->stop_update_lock); 632 cancel_work_sync(&vb->update_balloon_size_work); 633 cancel_work_sync(&vb->update_balloon_stats_work); 634 635 remove_common(vb); 636 #ifdef CONFIG_BALLOON_COMPACTION 637 if (vb->vb_dev_info.inode) 638 iput(vb->vb_dev_info.inode); 639 640 kern_unmount(balloon_mnt); 641 #endif 642 kfree(vb); 643 } 644 645 #ifdef CONFIG_PM_SLEEP 646 static int virtballoon_freeze(struct virtio_device *vdev) 647 { 648 struct virtio_balloon *vb = vdev->priv; 649 650 /* 651 * The workqueue is already frozen by the PM core before this 652 * function is called. 653 */ 654 remove_common(vb); 655 return 0; 656 } 657 658 static int virtballoon_restore(struct virtio_device *vdev) 659 { 660 struct virtio_balloon *vb = vdev->priv; 661 int ret; 662 663 ret = init_vqs(vdev->priv); 664 if (ret) 665 return ret; 666 667 virtio_device_ready(vdev); 668 669 if (towards_target(vb)) 670 virtballoon_changed(vdev); 671 update_balloon_size(vb); 672 return 0; 673 } 674 #endif 675 676 static int virtballoon_validate(struct virtio_device *vdev) 677 { 678 __virtio_clear_bit(vdev, VIRTIO_F_IOMMU_PLATFORM); 679 return 0; 680 } 681 682 static unsigned int features[] = { 683 VIRTIO_BALLOON_F_MUST_TELL_HOST, 684 VIRTIO_BALLOON_F_STATS_VQ, 685 VIRTIO_BALLOON_F_DEFLATE_ON_OOM, 686 }; 687 688 static struct virtio_driver virtio_balloon_driver = { 689 .feature_table = features, 690 .feature_table_size = ARRAY_SIZE(features), 691 .driver.name = KBUILD_MODNAME, 692 .driver.owner = THIS_MODULE, 693 .id_table = id_table, 694 .validate = virtballoon_validate, 695 .probe = virtballoon_probe, 696 .remove = virtballoon_remove, 697 .config_changed = virtballoon_changed, 698 #ifdef CONFIG_PM_SLEEP 699 .freeze = virtballoon_freeze, 700 .restore = virtballoon_restore, 701 #endif 702 }; 703 704 module_virtio_driver(virtio_balloon_driver); 705 MODULE_DEVICE_TABLE(virtio, id_table); 706 MODULE_DESCRIPTION("Virtio balloon driver"); 707 MODULE_LICENSE("GPL"); 708