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 struct page *balloon_pfn_to_page(u32 pfn) 108 { 109 BUG_ON(pfn % VIRTIO_BALLOON_PAGES_PER_PAGE); 110 return pfn_to_page(pfn / VIRTIO_BALLOON_PAGES_PER_PAGE); 111 } 112 113 static void balloon_ack(struct virtqueue *vq) 114 { 115 struct virtio_balloon *vb = vq->vdev->priv; 116 117 wake_up(&vb->acked); 118 } 119 120 static void tell_host(struct virtio_balloon *vb, struct virtqueue *vq) 121 { 122 struct scatterlist sg; 123 unsigned int len; 124 125 sg_init_one(&sg, vb->pfns, sizeof(vb->pfns[0]) * vb->num_pfns); 126 127 /* We should always be able to add one buffer to an empty queue. */ 128 virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL); 129 virtqueue_kick(vq); 130 131 /* When host has read buffer, this completes via balloon_ack */ 132 wait_event(vb->acked, virtqueue_get_buf(vq, &len)); 133 134 } 135 136 static void set_page_pfns(struct virtio_balloon *vb, 137 __virtio32 pfns[], struct page *page) 138 { 139 unsigned int i; 140 141 /* Set balloon pfns pointing at this page. 142 * Note that the first pfn points at start of the page. */ 143 for (i = 0; i < VIRTIO_BALLOON_PAGES_PER_PAGE; i++) 144 pfns[i] = cpu_to_virtio32(vb->vdev, 145 page_to_balloon_pfn(page) + i); 146 } 147 148 static unsigned fill_balloon(struct virtio_balloon *vb, size_t num) 149 { 150 struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info; 151 unsigned num_allocated_pages; 152 153 /* We can only do one array worth at a time. */ 154 num = min(num, ARRAY_SIZE(vb->pfns)); 155 156 mutex_lock(&vb->balloon_lock); 157 for (vb->num_pfns = 0; vb->num_pfns < num; 158 vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) { 159 struct page *page = balloon_page_enqueue(vb_dev_info); 160 161 if (!page) { 162 dev_info_ratelimited(&vb->vdev->dev, 163 "Out of puff! Can't get %u pages\n", 164 VIRTIO_BALLOON_PAGES_PER_PAGE); 165 /* Sleep for at least 1/5 of a second before retry. */ 166 msleep(200); 167 break; 168 } 169 set_page_pfns(vb, vb->pfns + vb->num_pfns, page); 170 vb->num_pages += VIRTIO_BALLOON_PAGES_PER_PAGE; 171 if (!virtio_has_feature(vb->vdev, 172 VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) 173 adjust_managed_page_count(page, -1); 174 } 175 176 num_allocated_pages = vb->num_pfns; 177 /* Did we get any? */ 178 if (vb->num_pfns != 0) 179 tell_host(vb, vb->inflate_vq); 180 mutex_unlock(&vb->balloon_lock); 181 182 return num_allocated_pages; 183 } 184 185 static void release_pages_balloon(struct virtio_balloon *vb) 186 { 187 unsigned int i; 188 struct page *page; 189 190 /* Find pfns pointing at start of each page, get pages and free them. */ 191 for (i = 0; i < vb->num_pfns; i += VIRTIO_BALLOON_PAGES_PER_PAGE) { 192 page = balloon_pfn_to_page(virtio32_to_cpu(vb->vdev, 193 vb->pfns[i])); 194 if (!virtio_has_feature(vb->vdev, 195 VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) 196 adjust_managed_page_count(page, 1); 197 put_page(page); /* balloon reference */ 198 } 199 } 200 201 static unsigned leak_balloon(struct virtio_balloon *vb, size_t num) 202 { 203 unsigned num_freed_pages; 204 struct page *page; 205 struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info; 206 207 /* We can only do one array worth at a time. */ 208 num = min(num, ARRAY_SIZE(vb->pfns)); 209 210 mutex_lock(&vb->balloon_lock); 211 /* We can't release more pages than taken */ 212 num = min(num, (size_t)vb->num_pages); 213 for (vb->num_pfns = 0; vb->num_pfns < num; 214 vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) { 215 page = balloon_page_dequeue(vb_dev_info); 216 if (!page) 217 break; 218 set_page_pfns(vb, vb->pfns + vb->num_pfns, page); 219 vb->num_pages -= VIRTIO_BALLOON_PAGES_PER_PAGE; 220 } 221 222 num_freed_pages = vb->num_pfns; 223 /* 224 * Note that if 225 * virtio_has_feature(vdev, VIRTIO_BALLOON_F_MUST_TELL_HOST); 226 * is true, we *have* to do it in this order 227 */ 228 if (vb->num_pfns != 0) 229 tell_host(vb, vb->deflate_vq); 230 release_pages_balloon(vb); 231 mutex_unlock(&vb->balloon_lock); 232 return num_freed_pages; 233 } 234 235 static inline void update_stat(struct virtio_balloon *vb, int idx, 236 u16 tag, u64 val) 237 { 238 BUG_ON(idx >= VIRTIO_BALLOON_S_NR); 239 vb->stats[idx].tag = cpu_to_virtio16(vb->vdev, tag); 240 vb->stats[idx].val = cpu_to_virtio64(vb->vdev, val); 241 } 242 243 #define pages_to_bytes(x) ((u64)(x) << PAGE_SHIFT) 244 245 static unsigned int update_balloon_stats(struct virtio_balloon *vb) 246 { 247 unsigned long events[NR_VM_EVENT_ITEMS]; 248 struct sysinfo i; 249 unsigned int idx = 0; 250 long available; 251 252 all_vm_events(events); 253 si_meminfo(&i); 254 255 available = si_mem_available(); 256 257 #ifdef CONFIG_VM_EVENT_COUNTERS 258 update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_IN, 259 pages_to_bytes(events[PSWPIN])); 260 update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_OUT, 261 pages_to_bytes(events[PSWPOUT])); 262 update_stat(vb, idx++, VIRTIO_BALLOON_S_MAJFLT, events[PGMAJFAULT]); 263 update_stat(vb, idx++, VIRTIO_BALLOON_S_MINFLT, events[PGFAULT]); 264 #endif 265 update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMFREE, 266 pages_to_bytes(i.freeram)); 267 update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMTOT, 268 pages_to_bytes(i.totalram)); 269 update_stat(vb, idx++, VIRTIO_BALLOON_S_AVAIL, 270 pages_to_bytes(available)); 271 272 return idx; 273 } 274 275 /* 276 * While most virtqueues communicate guest-initiated requests to the hypervisor, 277 * the stats queue operates in reverse. The driver initializes the virtqueue 278 * with a single buffer. From that point forward, all conversations consist of 279 * a hypervisor request (a call to this function) which directs us to refill 280 * the virtqueue with a fresh stats buffer. Since stats collection can sleep, 281 * we delegate the job to a freezable workqueue that will do the actual work via 282 * stats_handle_request(). 283 */ 284 static void stats_request(struct virtqueue *vq) 285 { 286 struct virtio_balloon *vb = vq->vdev->priv; 287 288 spin_lock(&vb->stop_update_lock); 289 if (!vb->stop_update) 290 queue_work(system_freezable_wq, &vb->update_balloon_stats_work); 291 spin_unlock(&vb->stop_update_lock); 292 } 293 294 static void stats_handle_request(struct virtio_balloon *vb) 295 { 296 struct virtqueue *vq; 297 struct scatterlist sg; 298 unsigned int len, num_stats; 299 300 num_stats = update_balloon_stats(vb); 301 302 vq = vb->stats_vq; 303 if (!virtqueue_get_buf(vq, &len)) 304 return; 305 sg_init_one(&sg, vb->stats, sizeof(vb->stats[0]) * num_stats); 306 virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL); 307 virtqueue_kick(vq); 308 } 309 310 static void virtballoon_changed(struct virtio_device *vdev) 311 { 312 struct virtio_balloon *vb = vdev->priv; 313 unsigned long flags; 314 315 spin_lock_irqsave(&vb->stop_update_lock, flags); 316 if (!vb->stop_update) 317 queue_work(system_freezable_wq, &vb->update_balloon_size_work); 318 spin_unlock_irqrestore(&vb->stop_update_lock, flags); 319 } 320 321 static inline s64 towards_target(struct virtio_balloon *vb) 322 { 323 s64 target; 324 u32 num_pages; 325 326 virtio_cread(vb->vdev, struct virtio_balloon_config, num_pages, 327 &num_pages); 328 329 /* Legacy balloon config space is LE, unlike all other devices. */ 330 if (!virtio_has_feature(vb->vdev, VIRTIO_F_VERSION_1)) 331 num_pages = le32_to_cpu((__force __le32)num_pages); 332 333 target = num_pages; 334 return target - vb->num_pages; 335 } 336 337 static void update_balloon_size(struct virtio_balloon *vb) 338 { 339 u32 actual = vb->num_pages; 340 341 /* Legacy balloon config space is LE, unlike all other devices. */ 342 if (!virtio_has_feature(vb->vdev, VIRTIO_F_VERSION_1)) 343 actual = (__force u32)cpu_to_le32(actual); 344 345 virtio_cwrite(vb->vdev, struct virtio_balloon_config, actual, 346 &actual); 347 } 348 349 /* 350 * virtballoon_oom_notify - release pages when system is under severe 351 * memory pressure (called from out_of_memory()) 352 * @self : notifier block struct 353 * @dummy: not used 354 * @parm : returned - number of freed pages 355 * 356 * The balancing of memory by use of the virtio balloon should not cause 357 * the termination of processes while there are pages in the balloon. 358 * If virtio balloon manages to release some memory, it will make the 359 * system return and retry the allocation that forced the OOM killer 360 * to run. 361 */ 362 static int virtballoon_oom_notify(struct notifier_block *self, 363 unsigned long dummy, void *parm) 364 { 365 struct virtio_balloon *vb; 366 unsigned long *freed; 367 unsigned num_freed_pages; 368 369 vb = container_of(self, struct virtio_balloon, nb); 370 if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) 371 return NOTIFY_OK; 372 373 freed = parm; 374 num_freed_pages = leak_balloon(vb, oom_pages); 375 update_balloon_size(vb); 376 *freed += num_freed_pages; 377 378 return NOTIFY_OK; 379 } 380 381 static void update_balloon_stats_func(struct work_struct *work) 382 { 383 struct virtio_balloon *vb; 384 385 vb = container_of(work, struct virtio_balloon, 386 update_balloon_stats_work); 387 stats_handle_request(vb); 388 } 389 390 static void update_balloon_size_func(struct work_struct *work) 391 { 392 struct virtio_balloon *vb; 393 s64 diff; 394 395 vb = container_of(work, struct virtio_balloon, 396 update_balloon_size_work); 397 diff = towards_target(vb); 398 399 if (diff > 0) 400 diff -= fill_balloon(vb, diff); 401 else if (diff < 0) 402 diff += leak_balloon(vb, -diff); 403 update_balloon_size(vb); 404 405 if (diff) 406 queue_work(system_freezable_wq, work); 407 } 408 409 static int init_vqs(struct virtio_balloon *vb) 410 { 411 struct virtqueue *vqs[3]; 412 vq_callback_t *callbacks[] = { balloon_ack, balloon_ack, stats_request }; 413 static const char * const names[] = { "inflate", "deflate", "stats" }; 414 int err, nvqs; 415 416 /* 417 * We expect two virtqueues: inflate and deflate, and 418 * optionally stat. 419 */ 420 nvqs = virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ) ? 3 : 2; 421 err = virtio_find_vqs(vb->vdev, nvqs, vqs, callbacks, names, NULL); 422 if (err) 423 return err; 424 425 vb->inflate_vq = vqs[0]; 426 vb->deflate_vq = vqs[1]; 427 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) { 428 struct scatterlist sg; 429 unsigned int num_stats; 430 vb->stats_vq = vqs[2]; 431 432 /* 433 * Prime this virtqueue with one buffer so the hypervisor can 434 * use it to signal us later (it can't be broken yet!). 435 */ 436 num_stats = update_balloon_stats(vb); 437 438 sg_init_one(&sg, vb->stats, sizeof(vb->stats[0]) * num_stats); 439 if (virtqueue_add_outbuf(vb->stats_vq, &sg, 1, vb, GFP_KERNEL) 440 < 0) 441 BUG(); 442 virtqueue_kick(vb->stats_vq); 443 } 444 return 0; 445 } 446 447 #ifdef CONFIG_BALLOON_COMPACTION 448 /* 449 * virtballoon_migratepage - perform the balloon page migration on behalf of 450 * a compation thread. (called under page lock) 451 * @vb_dev_info: the balloon device 452 * @newpage: page that will replace the isolated page after migration finishes. 453 * @page : the isolated (old) page that is about to be migrated to newpage. 454 * @mode : compaction mode -- not used for balloon page migration. 455 * 456 * After a ballooned page gets isolated by compaction procedures, this is the 457 * function that performs the page migration on behalf of a compaction thread 458 * The page migration for virtio balloon is done in a simple swap fashion which 459 * follows these two macro steps: 460 * 1) insert newpage into vb->pages list and update the host about it; 461 * 2) update the host about the old page removed from vb->pages list; 462 * 463 * This function preforms the balloon page migration task. 464 * Called through balloon_mapping->a_ops->migratepage 465 */ 466 static int virtballoon_migratepage(struct balloon_dev_info *vb_dev_info, 467 struct page *newpage, struct page *page, enum migrate_mode mode) 468 { 469 struct virtio_balloon *vb = container_of(vb_dev_info, 470 struct virtio_balloon, vb_dev_info); 471 unsigned long flags; 472 473 /* 474 * In order to avoid lock contention while migrating pages concurrently 475 * to leak_balloon() or fill_balloon() we just give up the balloon_lock 476 * this turn, as it is easier to retry the page migration later. 477 * This also prevents fill_balloon() getting stuck into a mutex 478 * recursion in the case it ends up triggering memory compaction 479 * while it is attempting to inflate the ballon. 480 */ 481 if (!mutex_trylock(&vb->balloon_lock)) 482 return -EAGAIN; 483 484 get_page(newpage); /* balloon reference */ 485 486 /* balloon's page migration 1st step -- inflate "newpage" */ 487 spin_lock_irqsave(&vb_dev_info->pages_lock, flags); 488 balloon_page_insert(vb_dev_info, newpage); 489 vb_dev_info->isolated_pages--; 490 __count_vm_event(BALLOON_MIGRATE); 491 spin_unlock_irqrestore(&vb_dev_info->pages_lock, flags); 492 vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE; 493 set_page_pfns(vb, vb->pfns, newpage); 494 tell_host(vb, vb->inflate_vq); 495 496 /* balloon's page migration 2nd step -- deflate "page" */ 497 balloon_page_delete(page); 498 vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE; 499 set_page_pfns(vb, vb->pfns, page); 500 tell_host(vb, vb->deflate_vq); 501 502 mutex_unlock(&vb->balloon_lock); 503 504 put_page(page); /* balloon reference */ 505 506 return MIGRATEPAGE_SUCCESS; 507 } 508 509 static struct dentry *balloon_mount(struct file_system_type *fs_type, 510 int flags, const char *dev_name, void *data) 511 { 512 static const struct dentry_operations ops = { 513 .d_dname = simple_dname, 514 }; 515 516 return mount_pseudo(fs_type, "balloon-kvm:", NULL, &ops, 517 BALLOON_KVM_MAGIC); 518 } 519 520 static struct file_system_type balloon_fs = { 521 .name = "balloon-kvm", 522 .mount = balloon_mount, 523 .kill_sb = kill_anon_super, 524 }; 525 526 #endif /* CONFIG_BALLOON_COMPACTION */ 527 528 static int virtballoon_probe(struct virtio_device *vdev) 529 { 530 struct virtio_balloon *vb; 531 int err; 532 533 if (!vdev->config->get) { 534 dev_err(&vdev->dev, "%s failure: config access disabled\n", 535 __func__); 536 return -EINVAL; 537 } 538 539 vdev->priv = vb = kmalloc(sizeof(*vb), GFP_KERNEL); 540 if (!vb) { 541 err = -ENOMEM; 542 goto out; 543 } 544 545 INIT_WORK(&vb->update_balloon_stats_work, update_balloon_stats_func); 546 INIT_WORK(&vb->update_balloon_size_work, update_balloon_size_func); 547 spin_lock_init(&vb->stop_update_lock); 548 vb->stop_update = false; 549 vb->num_pages = 0; 550 mutex_init(&vb->balloon_lock); 551 init_waitqueue_head(&vb->acked); 552 vb->vdev = vdev; 553 554 balloon_devinfo_init(&vb->vb_dev_info); 555 556 err = init_vqs(vb); 557 if (err) 558 goto out_free_vb; 559 560 vb->nb.notifier_call = virtballoon_oom_notify; 561 vb->nb.priority = VIRTBALLOON_OOM_NOTIFY_PRIORITY; 562 err = register_oom_notifier(&vb->nb); 563 if (err < 0) 564 goto out_del_vqs; 565 566 #ifdef CONFIG_BALLOON_COMPACTION 567 balloon_mnt = kern_mount(&balloon_fs); 568 if (IS_ERR(balloon_mnt)) { 569 err = PTR_ERR(balloon_mnt); 570 unregister_oom_notifier(&vb->nb); 571 goto out_del_vqs; 572 } 573 574 vb->vb_dev_info.migratepage = virtballoon_migratepage; 575 vb->vb_dev_info.inode = alloc_anon_inode(balloon_mnt->mnt_sb); 576 if (IS_ERR(vb->vb_dev_info.inode)) { 577 err = PTR_ERR(vb->vb_dev_info.inode); 578 kern_unmount(balloon_mnt); 579 unregister_oom_notifier(&vb->nb); 580 vb->vb_dev_info.inode = NULL; 581 goto out_del_vqs; 582 } 583 vb->vb_dev_info.inode->i_mapping->a_ops = &balloon_aops; 584 #endif 585 586 virtio_device_ready(vdev); 587 588 if (towards_target(vb)) 589 virtballoon_changed(vdev); 590 return 0; 591 592 out_del_vqs: 593 vdev->config->del_vqs(vdev); 594 out_free_vb: 595 kfree(vb); 596 out: 597 return err; 598 } 599 600 static void remove_common(struct virtio_balloon *vb) 601 { 602 /* There might be pages left in the balloon: free them. */ 603 while (vb->num_pages) 604 leak_balloon(vb, vb->num_pages); 605 update_balloon_size(vb); 606 607 /* Now we reset the device so we can clean up the queues. */ 608 vb->vdev->config->reset(vb->vdev); 609 610 vb->vdev->config->del_vqs(vb->vdev); 611 } 612 613 static void virtballoon_remove(struct virtio_device *vdev) 614 { 615 struct virtio_balloon *vb = vdev->priv; 616 617 unregister_oom_notifier(&vb->nb); 618 619 spin_lock_irq(&vb->stop_update_lock); 620 vb->stop_update = true; 621 spin_unlock_irq(&vb->stop_update_lock); 622 cancel_work_sync(&vb->update_balloon_size_work); 623 cancel_work_sync(&vb->update_balloon_stats_work); 624 625 remove_common(vb); 626 #ifdef CONFIG_BALLOON_COMPACTION 627 if (vb->vb_dev_info.inode) 628 iput(vb->vb_dev_info.inode); 629 630 kern_unmount(balloon_mnt); 631 #endif 632 kfree(vb); 633 } 634 635 #ifdef CONFIG_PM_SLEEP 636 static int virtballoon_freeze(struct virtio_device *vdev) 637 { 638 struct virtio_balloon *vb = vdev->priv; 639 640 /* 641 * The workqueue is already frozen by the PM core before this 642 * function is called. 643 */ 644 remove_common(vb); 645 return 0; 646 } 647 648 static int virtballoon_restore(struct virtio_device *vdev) 649 { 650 struct virtio_balloon *vb = vdev->priv; 651 int ret; 652 653 ret = init_vqs(vdev->priv); 654 if (ret) 655 return ret; 656 657 virtio_device_ready(vdev); 658 659 if (towards_target(vb)) 660 virtballoon_changed(vdev); 661 update_balloon_size(vb); 662 return 0; 663 } 664 #endif 665 666 static unsigned int features[] = { 667 VIRTIO_BALLOON_F_MUST_TELL_HOST, 668 VIRTIO_BALLOON_F_STATS_VQ, 669 VIRTIO_BALLOON_F_DEFLATE_ON_OOM, 670 }; 671 672 static struct virtio_driver virtio_balloon_driver = { 673 .feature_table = features, 674 .feature_table_size = ARRAY_SIZE(features), 675 .driver.name = KBUILD_MODNAME, 676 .driver.owner = THIS_MODULE, 677 .id_table = id_table, 678 .probe = virtballoon_probe, 679 .remove = virtballoon_remove, 680 .config_changed = virtballoon_changed, 681 #ifdef CONFIG_PM_SLEEP 682 .freeze = virtballoon_freeze, 683 .restore = virtballoon_restore, 684 #endif 685 }; 686 687 module_virtio_driver(virtio_balloon_driver); 688 MODULE_DEVICE_TABLE(virtio, id_table); 689 MODULE_DESCRIPTION("Virtio balloon driver"); 690 MODULE_LICENSE("GPL"); 691