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