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 unsigned long caches; 261 262 all_vm_events(events); 263 si_meminfo(&i); 264 265 available = si_mem_available(); 266 caches = global_node_page_state(NR_FILE_PAGES); 267 268 #ifdef CONFIG_VM_EVENT_COUNTERS 269 update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_IN, 270 pages_to_bytes(events[PSWPIN])); 271 update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_OUT, 272 pages_to_bytes(events[PSWPOUT])); 273 update_stat(vb, idx++, VIRTIO_BALLOON_S_MAJFLT, events[PGMAJFAULT]); 274 update_stat(vb, idx++, VIRTIO_BALLOON_S_MINFLT, events[PGFAULT]); 275 #endif 276 update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMFREE, 277 pages_to_bytes(i.freeram)); 278 update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMTOT, 279 pages_to_bytes(i.totalram)); 280 update_stat(vb, idx++, VIRTIO_BALLOON_S_AVAIL, 281 pages_to_bytes(available)); 282 update_stat(vb, idx++, VIRTIO_BALLOON_S_CACHES, 283 pages_to_bytes(caches)); 284 285 return idx; 286 } 287 288 /* 289 * While most virtqueues communicate guest-initiated requests to the hypervisor, 290 * the stats queue operates in reverse. The driver initializes the virtqueue 291 * with a single buffer. From that point forward, all conversations consist of 292 * a hypervisor request (a call to this function) which directs us to refill 293 * the virtqueue with a fresh stats buffer. Since stats collection can sleep, 294 * we delegate the job to a freezable workqueue that will do the actual work via 295 * stats_handle_request(). 296 */ 297 static void stats_request(struct virtqueue *vq) 298 { 299 struct virtio_balloon *vb = vq->vdev->priv; 300 301 spin_lock(&vb->stop_update_lock); 302 if (!vb->stop_update) 303 queue_work(system_freezable_wq, &vb->update_balloon_stats_work); 304 spin_unlock(&vb->stop_update_lock); 305 } 306 307 static void stats_handle_request(struct virtio_balloon *vb) 308 { 309 struct virtqueue *vq; 310 struct scatterlist sg; 311 unsigned int len, num_stats; 312 313 num_stats = update_balloon_stats(vb); 314 315 vq = vb->stats_vq; 316 if (!virtqueue_get_buf(vq, &len)) 317 return; 318 sg_init_one(&sg, vb->stats, sizeof(vb->stats[0]) * num_stats); 319 virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL); 320 virtqueue_kick(vq); 321 } 322 323 static void virtballoon_changed(struct virtio_device *vdev) 324 { 325 struct virtio_balloon *vb = vdev->priv; 326 unsigned long flags; 327 328 spin_lock_irqsave(&vb->stop_update_lock, flags); 329 if (!vb->stop_update) 330 queue_work(system_freezable_wq, &vb->update_balloon_size_work); 331 spin_unlock_irqrestore(&vb->stop_update_lock, flags); 332 } 333 334 static inline s64 towards_target(struct virtio_balloon *vb) 335 { 336 s64 target; 337 u32 num_pages; 338 339 virtio_cread(vb->vdev, struct virtio_balloon_config, num_pages, 340 &num_pages); 341 342 /* Legacy balloon config space is LE, unlike all other devices. */ 343 if (!virtio_has_feature(vb->vdev, VIRTIO_F_VERSION_1)) 344 num_pages = le32_to_cpu((__force __le32)num_pages); 345 346 target = num_pages; 347 return target - vb->num_pages; 348 } 349 350 static void update_balloon_size(struct virtio_balloon *vb) 351 { 352 u32 actual = vb->num_pages; 353 354 /* Legacy balloon config space is LE, unlike all other devices. */ 355 if (!virtio_has_feature(vb->vdev, VIRTIO_F_VERSION_1)) 356 actual = (__force u32)cpu_to_le32(actual); 357 358 virtio_cwrite(vb->vdev, struct virtio_balloon_config, actual, 359 &actual); 360 } 361 362 /* 363 * virtballoon_oom_notify - release pages when system is under severe 364 * memory pressure (called from out_of_memory()) 365 * @self : notifier block struct 366 * @dummy: not used 367 * @parm : returned - number of freed pages 368 * 369 * The balancing of memory by use of the virtio balloon should not cause 370 * the termination of processes while there are pages in the balloon. 371 * If virtio balloon manages to release some memory, it will make the 372 * system return and retry the allocation that forced the OOM killer 373 * to run. 374 */ 375 static int virtballoon_oom_notify(struct notifier_block *self, 376 unsigned long dummy, void *parm) 377 { 378 struct virtio_balloon *vb; 379 unsigned long *freed; 380 unsigned num_freed_pages; 381 382 vb = container_of(self, struct virtio_balloon, nb); 383 if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) 384 return NOTIFY_OK; 385 386 freed = parm; 387 num_freed_pages = leak_balloon(vb, oom_pages); 388 update_balloon_size(vb); 389 *freed += num_freed_pages; 390 391 return NOTIFY_OK; 392 } 393 394 static void update_balloon_stats_func(struct work_struct *work) 395 { 396 struct virtio_balloon *vb; 397 398 vb = container_of(work, struct virtio_balloon, 399 update_balloon_stats_work); 400 stats_handle_request(vb); 401 } 402 403 static void update_balloon_size_func(struct work_struct *work) 404 { 405 struct virtio_balloon *vb; 406 s64 diff; 407 408 vb = container_of(work, struct virtio_balloon, 409 update_balloon_size_work); 410 diff = towards_target(vb); 411 412 if (diff > 0) 413 diff -= fill_balloon(vb, diff); 414 else if (diff < 0) 415 diff += leak_balloon(vb, -diff); 416 update_balloon_size(vb); 417 418 if (diff) 419 queue_work(system_freezable_wq, work); 420 } 421 422 static int init_vqs(struct virtio_balloon *vb) 423 { 424 struct virtqueue *vqs[3]; 425 vq_callback_t *callbacks[] = { balloon_ack, balloon_ack, stats_request }; 426 static const char * const names[] = { "inflate", "deflate", "stats" }; 427 int err, nvqs; 428 429 /* 430 * We expect two virtqueues: inflate and deflate, and 431 * optionally stat. 432 */ 433 nvqs = virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ) ? 3 : 2; 434 err = virtio_find_vqs(vb->vdev, nvqs, vqs, callbacks, names, NULL); 435 if (err) 436 return err; 437 438 vb->inflate_vq = vqs[0]; 439 vb->deflate_vq = vqs[1]; 440 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) { 441 struct scatterlist sg; 442 unsigned int num_stats; 443 vb->stats_vq = vqs[2]; 444 445 /* 446 * Prime this virtqueue with one buffer so the hypervisor can 447 * use it to signal us later (it can't be broken yet!). 448 */ 449 num_stats = update_balloon_stats(vb); 450 451 sg_init_one(&sg, vb->stats, sizeof(vb->stats[0]) * num_stats); 452 if (virtqueue_add_outbuf(vb->stats_vq, &sg, 1, vb, GFP_KERNEL) 453 < 0) 454 BUG(); 455 virtqueue_kick(vb->stats_vq); 456 } 457 return 0; 458 } 459 460 #ifdef CONFIG_BALLOON_COMPACTION 461 /* 462 * virtballoon_migratepage - perform the balloon page migration on behalf of 463 * a compation thread. (called under page lock) 464 * @vb_dev_info: the balloon device 465 * @newpage: page that will replace the isolated page after migration finishes. 466 * @page : the isolated (old) page that is about to be migrated to newpage. 467 * @mode : compaction mode -- not used for balloon page migration. 468 * 469 * After a ballooned page gets isolated by compaction procedures, this is the 470 * function that performs the page migration on behalf of a compaction thread 471 * The page migration for virtio balloon is done in a simple swap fashion which 472 * follows these two macro steps: 473 * 1) insert newpage into vb->pages list and update the host about it; 474 * 2) update the host about the old page removed from vb->pages list; 475 * 476 * This function preforms the balloon page migration task. 477 * Called through balloon_mapping->a_ops->migratepage 478 */ 479 static int virtballoon_migratepage(struct balloon_dev_info *vb_dev_info, 480 struct page *newpage, struct page *page, enum migrate_mode mode) 481 { 482 struct virtio_balloon *vb = container_of(vb_dev_info, 483 struct virtio_balloon, vb_dev_info); 484 unsigned long flags; 485 486 /* 487 * In order to avoid lock contention while migrating pages concurrently 488 * to leak_balloon() or fill_balloon() we just give up the balloon_lock 489 * this turn, as it is easier to retry the page migration later. 490 * This also prevents fill_balloon() getting stuck into a mutex 491 * recursion in the case it ends up triggering memory compaction 492 * while it is attempting to inflate the ballon. 493 */ 494 if (!mutex_trylock(&vb->balloon_lock)) 495 return -EAGAIN; 496 497 get_page(newpage); /* balloon reference */ 498 499 /* balloon's page migration 1st step -- inflate "newpage" */ 500 spin_lock_irqsave(&vb_dev_info->pages_lock, flags); 501 balloon_page_insert(vb_dev_info, newpage); 502 vb_dev_info->isolated_pages--; 503 __count_vm_event(BALLOON_MIGRATE); 504 spin_unlock_irqrestore(&vb_dev_info->pages_lock, flags); 505 vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE; 506 set_page_pfns(vb, vb->pfns, newpage); 507 tell_host(vb, vb->inflate_vq); 508 509 /* balloon's page migration 2nd step -- deflate "page" */ 510 balloon_page_delete(page); 511 vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE; 512 set_page_pfns(vb, vb->pfns, page); 513 tell_host(vb, vb->deflate_vq); 514 515 mutex_unlock(&vb->balloon_lock); 516 517 put_page(page); /* balloon reference */ 518 519 return MIGRATEPAGE_SUCCESS; 520 } 521 522 static struct dentry *balloon_mount(struct file_system_type *fs_type, 523 int flags, const char *dev_name, void *data) 524 { 525 static const struct dentry_operations ops = { 526 .d_dname = simple_dname, 527 }; 528 529 return mount_pseudo(fs_type, "balloon-kvm:", NULL, &ops, 530 BALLOON_KVM_MAGIC); 531 } 532 533 static struct file_system_type balloon_fs = { 534 .name = "balloon-kvm", 535 .mount = balloon_mount, 536 .kill_sb = kill_anon_super, 537 }; 538 539 #endif /* CONFIG_BALLOON_COMPACTION */ 540 541 static int virtballoon_probe(struct virtio_device *vdev) 542 { 543 struct virtio_balloon *vb; 544 int err; 545 546 if (!vdev->config->get) { 547 dev_err(&vdev->dev, "%s failure: config access disabled\n", 548 __func__); 549 return -EINVAL; 550 } 551 552 vdev->priv = vb = kmalloc(sizeof(*vb), GFP_KERNEL); 553 if (!vb) { 554 err = -ENOMEM; 555 goto out; 556 } 557 558 INIT_WORK(&vb->update_balloon_stats_work, update_balloon_stats_func); 559 INIT_WORK(&vb->update_balloon_size_work, update_balloon_size_func); 560 spin_lock_init(&vb->stop_update_lock); 561 vb->stop_update = false; 562 vb->num_pages = 0; 563 mutex_init(&vb->balloon_lock); 564 init_waitqueue_head(&vb->acked); 565 vb->vdev = vdev; 566 567 balloon_devinfo_init(&vb->vb_dev_info); 568 569 err = init_vqs(vb); 570 if (err) 571 goto out_free_vb; 572 573 vb->nb.notifier_call = virtballoon_oom_notify; 574 vb->nb.priority = VIRTBALLOON_OOM_NOTIFY_PRIORITY; 575 err = register_oom_notifier(&vb->nb); 576 if (err < 0) 577 goto out_del_vqs; 578 579 #ifdef CONFIG_BALLOON_COMPACTION 580 balloon_mnt = kern_mount(&balloon_fs); 581 if (IS_ERR(balloon_mnt)) { 582 err = PTR_ERR(balloon_mnt); 583 unregister_oom_notifier(&vb->nb); 584 goto out_del_vqs; 585 } 586 587 vb->vb_dev_info.migratepage = virtballoon_migratepage; 588 vb->vb_dev_info.inode = alloc_anon_inode(balloon_mnt->mnt_sb); 589 if (IS_ERR(vb->vb_dev_info.inode)) { 590 err = PTR_ERR(vb->vb_dev_info.inode); 591 kern_unmount(balloon_mnt); 592 unregister_oom_notifier(&vb->nb); 593 vb->vb_dev_info.inode = NULL; 594 goto out_del_vqs; 595 } 596 vb->vb_dev_info.inode->i_mapping->a_ops = &balloon_aops; 597 #endif 598 599 virtio_device_ready(vdev); 600 601 if (towards_target(vb)) 602 virtballoon_changed(vdev); 603 return 0; 604 605 out_del_vqs: 606 vdev->config->del_vqs(vdev); 607 out_free_vb: 608 kfree(vb); 609 out: 610 return err; 611 } 612 613 static void remove_common(struct virtio_balloon *vb) 614 { 615 /* There might be pages left in the balloon: free them. */ 616 while (vb->num_pages) 617 leak_balloon(vb, vb->num_pages); 618 update_balloon_size(vb); 619 620 /* Now we reset the device so we can clean up the queues. */ 621 vb->vdev->config->reset(vb->vdev); 622 623 vb->vdev->config->del_vqs(vb->vdev); 624 } 625 626 static void virtballoon_remove(struct virtio_device *vdev) 627 { 628 struct virtio_balloon *vb = vdev->priv; 629 630 unregister_oom_notifier(&vb->nb); 631 632 spin_lock_irq(&vb->stop_update_lock); 633 vb->stop_update = true; 634 spin_unlock_irq(&vb->stop_update_lock); 635 cancel_work_sync(&vb->update_balloon_size_work); 636 cancel_work_sync(&vb->update_balloon_stats_work); 637 638 remove_common(vb); 639 #ifdef CONFIG_BALLOON_COMPACTION 640 if (vb->vb_dev_info.inode) 641 iput(vb->vb_dev_info.inode); 642 643 kern_unmount(balloon_mnt); 644 #endif 645 kfree(vb); 646 } 647 648 #ifdef CONFIG_PM_SLEEP 649 static int virtballoon_freeze(struct virtio_device *vdev) 650 { 651 struct virtio_balloon *vb = vdev->priv; 652 653 /* 654 * The workqueue is already frozen by the PM core before this 655 * function is called. 656 */ 657 remove_common(vb); 658 return 0; 659 } 660 661 static int virtballoon_restore(struct virtio_device *vdev) 662 { 663 struct virtio_balloon *vb = vdev->priv; 664 int ret; 665 666 ret = init_vqs(vdev->priv); 667 if (ret) 668 return ret; 669 670 virtio_device_ready(vdev); 671 672 if (towards_target(vb)) 673 virtballoon_changed(vdev); 674 update_balloon_size(vb); 675 return 0; 676 } 677 #endif 678 679 static int virtballoon_validate(struct virtio_device *vdev) 680 { 681 __virtio_clear_bit(vdev, VIRTIO_F_IOMMU_PLATFORM); 682 return 0; 683 } 684 685 static unsigned int features[] = { 686 VIRTIO_BALLOON_F_MUST_TELL_HOST, 687 VIRTIO_BALLOON_F_STATS_VQ, 688 VIRTIO_BALLOON_F_DEFLATE_ON_OOM, 689 }; 690 691 static struct virtio_driver virtio_balloon_driver = { 692 .feature_table = features, 693 .feature_table_size = ARRAY_SIZE(features), 694 .driver.name = KBUILD_MODNAME, 695 .driver.owner = THIS_MODULE, 696 .id_table = id_table, 697 .validate = virtballoon_validate, 698 .probe = virtballoon_probe, 699 .remove = virtballoon_remove, 700 .config_changed = virtballoon_changed, 701 #ifdef CONFIG_PM_SLEEP 702 .freeze = virtballoon_freeze, 703 .restore = virtballoon_restore, 704 #endif 705 }; 706 707 module_virtio_driver(virtio_balloon_driver); 708 MODULE_DEVICE_TABLE(virtio, id_table); 709 MODULE_DESCRIPTION("Virtio balloon driver"); 710 MODULE_LICENSE("GPL"); 711