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/wait.h> 31 #include <linux/mm.h> 32 #include <linux/mount.h> 33 #include <linux/magic.h> 34 35 /* 36 * Balloon device works in 4K page units. So each page is pointed to by 37 * multiple balloon pages. All memory counters in this driver are in balloon 38 * page units. 39 */ 40 #define VIRTIO_BALLOON_PAGES_PER_PAGE (unsigned)(PAGE_SIZE >> VIRTIO_BALLOON_PFN_SHIFT) 41 #define VIRTIO_BALLOON_ARRAY_PFNS_MAX 256 42 #define VIRTBALLOON_OOM_NOTIFY_PRIORITY 80 43 44 #ifdef CONFIG_BALLOON_COMPACTION 45 static struct vfsmount *balloon_mnt; 46 #endif 47 48 struct virtio_balloon { 49 struct virtio_device *vdev; 50 struct virtqueue *inflate_vq, *deflate_vq, *stats_vq; 51 52 /* The balloon servicing is delegated to a freezable workqueue. */ 53 struct work_struct update_balloon_stats_work; 54 struct work_struct update_balloon_size_work; 55 56 /* Prevent updating balloon when it is being canceled. */ 57 spinlock_t stop_update_lock; 58 bool stop_update; 59 60 /* Waiting for host to ack the pages we released. */ 61 wait_queue_head_t acked; 62 63 /* Number of balloon pages we've told the Host we're not using. */ 64 unsigned int num_pages; 65 /* 66 * The pages we've told the Host we're not using are enqueued 67 * at vb_dev_info->pages list. 68 * Each page on this list adds VIRTIO_BALLOON_PAGES_PER_PAGE 69 * to num_pages above. 70 */ 71 struct balloon_dev_info vb_dev_info; 72 73 /* Synchronize access/update to this struct virtio_balloon elements */ 74 struct mutex balloon_lock; 75 76 /* The array of pfns we tell the Host about. */ 77 unsigned int num_pfns; 78 __virtio32 pfns[VIRTIO_BALLOON_ARRAY_PFNS_MAX]; 79 80 /* Memory statistics */ 81 struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR]; 82 83 /* To register a shrinker to shrink memory upon memory pressure */ 84 struct shrinker shrinker; 85 }; 86 87 static struct virtio_device_id id_table[] = { 88 { VIRTIO_ID_BALLOON, VIRTIO_DEV_ANY_ID }, 89 { 0 }, 90 }; 91 92 static u32 page_to_balloon_pfn(struct page *page) 93 { 94 unsigned long pfn = page_to_pfn(page); 95 96 BUILD_BUG_ON(PAGE_SHIFT < VIRTIO_BALLOON_PFN_SHIFT); 97 /* Convert pfn from Linux page size to balloon page size. */ 98 return pfn * VIRTIO_BALLOON_PAGES_PER_PAGE; 99 } 100 101 static void balloon_ack(struct virtqueue *vq) 102 { 103 struct virtio_balloon *vb = vq->vdev->priv; 104 105 wake_up(&vb->acked); 106 } 107 108 static void tell_host(struct virtio_balloon *vb, struct virtqueue *vq) 109 { 110 struct scatterlist sg; 111 unsigned int len; 112 113 sg_init_one(&sg, vb->pfns, sizeof(vb->pfns[0]) * vb->num_pfns); 114 115 /* We should always be able to add one buffer to an empty queue. */ 116 virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL); 117 virtqueue_kick(vq); 118 119 /* When host has read buffer, this completes via balloon_ack */ 120 wait_event(vb->acked, virtqueue_get_buf(vq, &len)); 121 122 } 123 124 static void set_page_pfns(struct virtio_balloon *vb, 125 __virtio32 pfns[], struct page *page) 126 { 127 unsigned int i; 128 129 /* 130 * Set balloon pfns pointing at this page. 131 * Note that the first pfn points at start of the page. 132 */ 133 for (i = 0; i < VIRTIO_BALLOON_PAGES_PER_PAGE; i++) 134 pfns[i] = cpu_to_virtio32(vb->vdev, 135 page_to_balloon_pfn(page) + i); 136 } 137 138 static unsigned fill_balloon(struct virtio_balloon *vb, size_t num) 139 { 140 unsigned num_allocated_pages; 141 unsigned num_pfns; 142 struct page *page; 143 LIST_HEAD(pages); 144 145 /* We can only do one array worth at a time. */ 146 num = min(num, ARRAY_SIZE(vb->pfns)); 147 148 for (num_pfns = 0; num_pfns < num; 149 num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) { 150 struct page *page = balloon_page_alloc(); 151 152 if (!page) { 153 dev_info_ratelimited(&vb->vdev->dev, 154 "Out of puff! Can't get %u pages\n", 155 VIRTIO_BALLOON_PAGES_PER_PAGE); 156 /* Sleep for at least 1/5 of a second before retry. */ 157 msleep(200); 158 break; 159 } 160 161 balloon_page_push(&pages, page); 162 } 163 164 mutex_lock(&vb->balloon_lock); 165 166 vb->num_pfns = 0; 167 168 while ((page = balloon_page_pop(&pages))) { 169 balloon_page_enqueue(&vb->vb_dev_info, page); 170 171 set_page_pfns(vb, vb->pfns + vb->num_pfns, page); 172 vb->num_pages += VIRTIO_BALLOON_PAGES_PER_PAGE; 173 if (!virtio_has_feature(vb->vdev, 174 VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) 175 adjust_managed_page_count(page, -1); 176 vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE; 177 } 178 179 num_allocated_pages = vb->num_pfns; 180 /* Did we get any? */ 181 if (vb->num_pfns != 0) 182 tell_host(vb, vb->inflate_vq); 183 mutex_unlock(&vb->balloon_lock); 184 185 return num_allocated_pages; 186 } 187 188 static void release_pages_balloon(struct virtio_balloon *vb, 189 struct list_head *pages) 190 { 191 struct page *page, *next; 192 193 list_for_each_entry_safe(page, next, pages, lru) { 194 if (!virtio_has_feature(vb->vdev, 195 VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) 196 adjust_managed_page_count(page, 1); 197 list_del(&page->lru); 198 put_page(page); /* balloon reference */ 199 } 200 } 201 202 static unsigned leak_balloon(struct virtio_balloon *vb, size_t num) 203 { 204 unsigned num_freed_pages; 205 struct page *page; 206 struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info; 207 LIST_HEAD(pages); 208 209 /* We can only do one array worth at a time. */ 210 num = min(num, ARRAY_SIZE(vb->pfns)); 211 212 mutex_lock(&vb->balloon_lock); 213 /* We can't release more pages than taken */ 214 num = min(num, (size_t)vb->num_pages); 215 for (vb->num_pfns = 0; vb->num_pfns < num; 216 vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) { 217 page = balloon_page_dequeue(vb_dev_info); 218 if (!page) 219 break; 220 set_page_pfns(vb, vb->pfns + vb->num_pfns, page); 221 list_add(&page->lru, &pages); 222 vb->num_pages -= VIRTIO_BALLOON_PAGES_PER_PAGE; 223 } 224 225 num_freed_pages = vb->num_pfns; 226 /* 227 * Note that if 228 * virtio_has_feature(vdev, VIRTIO_BALLOON_F_MUST_TELL_HOST); 229 * is true, we *have* to do it in this order 230 */ 231 if (vb->num_pfns != 0) 232 tell_host(vb, vb->deflate_vq); 233 release_pages_balloon(vb, &pages); 234 mutex_unlock(&vb->balloon_lock); 235 return num_freed_pages; 236 } 237 238 static inline void update_stat(struct virtio_balloon *vb, int idx, 239 u16 tag, u64 val) 240 { 241 BUG_ON(idx >= VIRTIO_BALLOON_S_NR); 242 vb->stats[idx].tag = cpu_to_virtio16(vb->vdev, tag); 243 vb->stats[idx].val = cpu_to_virtio64(vb->vdev, val); 244 } 245 246 #define pages_to_bytes(x) ((u64)(x) << PAGE_SHIFT) 247 248 static unsigned int update_balloon_stats(struct virtio_balloon *vb) 249 { 250 unsigned long events[NR_VM_EVENT_ITEMS]; 251 struct sysinfo i; 252 unsigned int idx = 0; 253 long available; 254 unsigned long caches; 255 256 all_vm_events(events); 257 si_meminfo(&i); 258 259 available = si_mem_available(); 260 caches = global_node_page_state(NR_FILE_PAGES); 261 262 #ifdef CONFIG_VM_EVENT_COUNTERS 263 update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_IN, 264 pages_to_bytes(events[PSWPIN])); 265 update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_OUT, 266 pages_to_bytes(events[PSWPOUT])); 267 update_stat(vb, idx++, VIRTIO_BALLOON_S_MAJFLT, events[PGMAJFAULT]); 268 update_stat(vb, idx++, VIRTIO_BALLOON_S_MINFLT, events[PGFAULT]); 269 #ifdef CONFIG_HUGETLB_PAGE 270 update_stat(vb, idx++, VIRTIO_BALLOON_S_HTLB_PGALLOC, 271 events[HTLB_BUDDY_PGALLOC]); 272 update_stat(vb, idx++, VIRTIO_BALLOON_S_HTLB_PGFAIL, 273 events[HTLB_BUDDY_PGALLOC_FAIL]); 274 #endif 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 static void update_balloon_stats_func(struct work_struct *work) 363 { 364 struct virtio_balloon *vb; 365 366 vb = container_of(work, struct virtio_balloon, 367 update_balloon_stats_work); 368 stats_handle_request(vb); 369 } 370 371 static void update_balloon_size_func(struct work_struct *work) 372 { 373 struct virtio_balloon *vb; 374 s64 diff; 375 376 vb = container_of(work, struct virtio_balloon, 377 update_balloon_size_work); 378 diff = towards_target(vb); 379 380 if (diff > 0) 381 diff -= fill_balloon(vb, diff); 382 else if (diff < 0) 383 diff += leak_balloon(vb, -diff); 384 update_balloon_size(vb); 385 386 if (diff) 387 queue_work(system_freezable_wq, work); 388 } 389 390 static int init_vqs(struct virtio_balloon *vb) 391 { 392 struct virtqueue *vqs[3]; 393 vq_callback_t *callbacks[] = { balloon_ack, balloon_ack, stats_request }; 394 static const char * const names[] = { "inflate", "deflate", "stats" }; 395 int err, nvqs; 396 397 /* 398 * We expect two virtqueues: inflate and deflate, and 399 * optionally stat. 400 */ 401 nvqs = virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ) ? 3 : 2; 402 err = virtio_find_vqs(vb->vdev, nvqs, vqs, callbacks, names, NULL); 403 if (err) 404 return err; 405 406 vb->inflate_vq = vqs[0]; 407 vb->deflate_vq = vqs[1]; 408 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) { 409 struct scatterlist sg; 410 unsigned int num_stats; 411 vb->stats_vq = vqs[2]; 412 413 /* 414 * Prime this virtqueue with one buffer so the hypervisor can 415 * use it to signal us later (it can't be broken yet!). 416 */ 417 num_stats = update_balloon_stats(vb); 418 419 sg_init_one(&sg, vb->stats, sizeof(vb->stats[0]) * num_stats); 420 err = virtqueue_add_outbuf(vb->stats_vq, &sg, 1, vb, 421 GFP_KERNEL); 422 if (err) { 423 dev_warn(&vb->vdev->dev, "%s: add stat_vq failed\n", 424 __func__); 425 return err; 426 } 427 virtqueue_kick(vb->stats_vq); 428 } 429 return 0; 430 } 431 432 #ifdef CONFIG_BALLOON_COMPACTION 433 /* 434 * virtballoon_migratepage - perform the balloon page migration on behalf of 435 * a compation thread. (called under page lock) 436 * @vb_dev_info: the balloon device 437 * @newpage: page that will replace the isolated page after migration finishes. 438 * @page : the isolated (old) page that is about to be migrated to newpage. 439 * @mode : compaction mode -- not used for balloon page migration. 440 * 441 * After a ballooned page gets isolated by compaction procedures, this is the 442 * function that performs the page migration on behalf of a compaction thread 443 * The page migration for virtio balloon is done in a simple swap fashion which 444 * follows these two macro steps: 445 * 1) insert newpage into vb->pages list and update the host about it; 446 * 2) update the host about the old page removed from vb->pages list; 447 * 448 * This function preforms the balloon page migration task. 449 * Called through balloon_mapping->a_ops->migratepage 450 */ 451 static int virtballoon_migratepage(struct balloon_dev_info *vb_dev_info, 452 struct page *newpage, struct page *page, enum migrate_mode mode) 453 { 454 struct virtio_balloon *vb = container_of(vb_dev_info, 455 struct virtio_balloon, vb_dev_info); 456 unsigned long flags; 457 458 /* 459 * In order to avoid lock contention while migrating pages concurrently 460 * to leak_balloon() or fill_balloon() we just give up the balloon_lock 461 * this turn, as it is easier to retry the page migration later. 462 * This also prevents fill_balloon() getting stuck into a mutex 463 * recursion in the case it ends up triggering memory compaction 464 * while it is attempting to inflate the ballon. 465 */ 466 if (!mutex_trylock(&vb->balloon_lock)) 467 return -EAGAIN; 468 469 get_page(newpage); /* balloon reference */ 470 471 /* balloon's page migration 1st step -- inflate "newpage" */ 472 spin_lock_irqsave(&vb_dev_info->pages_lock, flags); 473 balloon_page_insert(vb_dev_info, newpage); 474 vb_dev_info->isolated_pages--; 475 __count_vm_event(BALLOON_MIGRATE); 476 spin_unlock_irqrestore(&vb_dev_info->pages_lock, flags); 477 vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE; 478 set_page_pfns(vb, vb->pfns, newpage); 479 tell_host(vb, vb->inflate_vq); 480 481 /* balloon's page migration 2nd step -- deflate "page" */ 482 spin_lock_irqsave(&vb_dev_info->pages_lock, flags); 483 balloon_page_delete(page); 484 spin_unlock_irqrestore(&vb_dev_info->pages_lock, flags); 485 vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE; 486 set_page_pfns(vb, vb->pfns, page); 487 tell_host(vb, vb->deflate_vq); 488 489 mutex_unlock(&vb->balloon_lock); 490 491 put_page(page); /* balloon reference */ 492 493 return MIGRATEPAGE_SUCCESS; 494 } 495 496 static struct dentry *balloon_mount(struct file_system_type *fs_type, 497 int flags, const char *dev_name, void *data) 498 { 499 static const struct dentry_operations ops = { 500 .d_dname = simple_dname, 501 }; 502 503 return mount_pseudo(fs_type, "balloon-kvm:", NULL, &ops, 504 BALLOON_KVM_MAGIC); 505 } 506 507 static struct file_system_type balloon_fs = { 508 .name = "balloon-kvm", 509 .mount = balloon_mount, 510 .kill_sb = kill_anon_super, 511 }; 512 513 #endif /* CONFIG_BALLOON_COMPACTION */ 514 515 static unsigned long virtio_balloon_shrinker_scan(struct shrinker *shrinker, 516 struct shrink_control *sc) 517 { 518 unsigned long pages_to_free, pages_freed = 0; 519 struct virtio_balloon *vb = container_of(shrinker, 520 struct virtio_balloon, shrinker); 521 522 pages_to_free = sc->nr_to_scan * VIRTIO_BALLOON_PAGES_PER_PAGE; 523 524 /* 525 * One invocation of leak_balloon can deflate at most 526 * VIRTIO_BALLOON_ARRAY_PFNS_MAX balloon pages, so we call it 527 * multiple times to deflate pages till reaching pages_to_free. 528 */ 529 while (vb->num_pages && pages_to_free) { 530 pages_to_free -= pages_freed; 531 pages_freed += leak_balloon(vb, pages_to_free); 532 } 533 update_balloon_size(vb); 534 535 return pages_freed / VIRTIO_BALLOON_PAGES_PER_PAGE; 536 } 537 538 static unsigned long virtio_balloon_shrinker_count(struct shrinker *shrinker, 539 struct shrink_control *sc) 540 { 541 struct virtio_balloon *vb = container_of(shrinker, 542 struct virtio_balloon, shrinker); 543 544 return vb->num_pages / VIRTIO_BALLOON_PAGES_PER_PAGE; 545 } 546 547 static void virtio_balloon_unregister_shrinker(struct virtio_balloon *vb) 548 { 549 unregister_shrinker(&vb->shrinker); 550 } 551 552 static int virtio_balloon_register_shrinker(struct virtio_balloon *vb) 553 { 554 vb->shrinker.scan_objects = virtio_balloon_shrinker_scan; 555 vb->shrinker.count_objects = virtio_balloon_shrinker_count; 556 vb->shrinker.seeks = DEFAULT_SEEKS; 557 558 return register_shrinker(&vb->shrinker); 559 } 560 561 static int virtballoon_probe(struct virtio_device *vdev) 562 { 563 struct virtio_balloon *vb; 564 int err; 565 566 if (!vdev->config->get) { 567 dev_err(&vdev->dev, "%s failure: config access disabled\n", 568 __func__); 569 return -EINVAL; 570 } 571 572 vdev->priv = vb = kzalloc(sizeof(*vb), GFP_KERNEL); 573 if (!vb) { 574 err = -ENOMEM; 575 goto out; 576 } 577 578 INIT_WORK(&vb->update_balloon_stats_work, update_balloon_stats_func); 579 INIT_WORK(&vb->update_balloon_size_work, update_balloon_size_func); 580 spin_lock_init(&vb->stop_update_lock); 581 mutex_init(&vb->balloon_lock); 582 init_waitqueue_head(&vb->acked); 583 vb->vdev = vdev; 584 585 balloon_devinfo_init(&vb->vb_dev_info); 586 587 err = init_vqs(vb); 588 if (err) 589 goto out_free_vb; 590 591 #ifdef CONFIG_BALLOON_COMPACTION 592 balloon_mnt = kern_mount(&balloon_fs); 593 if (IS_ERR(balloon_mnt)) { 594 err = PTR_ERR(balloon_mnt); 595 goto out_del_vqs; 596 } 597 598 vb->vb_dev_info.migratepage = virtballoon_migratepage; 599 vb->vb_dev_info.inode = alloc_anon_inode(balloon_mnt->mnt_sb); 600 if (IS_ERR(vb->vb_dev_info.inode)) { 601 err = PTR_ERR(vb->vb_dev_info.inode); 602 kern_unmount(balloon_mnt); 603 goto out_del_vqs; 604 } 605 vb->vb_dev_info.inode->i_mapping->a_ops = &balloon_aops; 606 #endif 607 /* 608 * We continue to use VIRTIO_BALLOON_F_DEFLATE_ON_OOM to decide if a 609 * shrinker needs to be registered to relieve memory pressure. 610 */ 611 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) { 612 err = virtio_balloon_register_shrinker(vb); 613 if (err) 614 goto out_del_vqs; 615 } 616 virtio_device_ready(vdev); 617 618 if (towards_target(vb)) 619 virtballoon_changed(vdev); 620 return 0; 621 622 out_del_vqs: 623 vdev->config->del_vqs(vdev); 624 out_free_vb: 625 kfree(vb); 626 out: 627 return err; 628 } 629 630 static void remove_common(struct virtio_balloon *vb) 631 { 632 /* There might be pages left in the balloon: free them. */ 633 while (vb->num_pages) 634 leak_balloon(vb, vb->num_pages); 635 update_balloon_size(vb); 636 637 /* Now we reset the device so we can clean up the queues. */ 638 vb->vdev->config->reset(vb->vdev); 639 640 vb->vdev->config->del_vqs(vb->vdev); 641 } 642 643 static void virtballoon_remove(struct virtio_device *vdev) 644 { 645 struct virtio_balloon *vb = vdev->priv; 646 647 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) 648 virtio_balloon_unregister_shrinker(vb); 649 spin_lock_irq(&vb->stop_update_lock); 650 vb->stop_update = true; 651 spin_unlock_irq(&vb->stop_update_lock); 652 cancel_work_sync(&vb->update_balloon_size_work); 653 cancel_work_sync(&vb->update_balloon_stats_work); 654 655 remove_common(vb); 656 #ifdef CONFIG_BALLOON_COMPACTION 657 if (vb->vb_dev_info.inode) 658 iput(vb->vb_dev_info.inode); 659 660 kern_unmount(balloon_mnt); 661 #endif 662 kfree(vb); 663 } 664 665 #ifdef CONFIG_PM_SLEEP 666 static int virtballoon_freeze(struct virtio_device *vdev) 667 { 668 struct virtio_balloon *vb = vdev->priv; 669 670 /* 671 * The workqueue is already frozen by the PM core before this 672 * function is called. 673 */ 674 remove_common(vb); 675 return 0; 676 } 677 678 static int virtballoon_restore(struct virtio_device *vdev) 679 { 680 struct virtio_balloon *vb = vdev->priv; 681 int ret; 682 683 ret = init_vqs(vdev->priv); 684 if (ret) 685 return ret; 686 687 virtio_device_ready(vdev); 688 689 if (towards_target(vb)) 690 virtballoon_changed(vdev); 691 update_balloon_size(vb); 692 return 0; 693 } 694 #endif 695 696 static int virtballoon_validate(struct virtio_device *vdev) 697 { 698 __virtio_clear_bit(vdev, VIRTIO_F_IOMMU_PLATFORM); 699 return 0; 700 } 701 702 static unsigned int features[] = { 703 VIRTIO_BALLOON_F_MUST_TELL_HOST, 704 VIRTIO_BALLOON_F_STATS_VQ, 705 VIRTIO_BALLOON_F_DEFLATE_ON_OOM, 706 }; 707 708 static struct virtio_driver virtio_balloon_driver = { 709 .feature_table = features, 710 .feature_table_size = ARRAY_SIZE(features), 711 .driver.name = KBUILD_MODNAME, 712 .driver.owner = THIS_MODULE, 713 .id_table = id_table, 714 .validate = virtballoon_validate, 715 .probe = virtballoon_probe, 716 .remove = virtballoon_remove, 717 .config_changed = virtballoon_changed, 718 #ifdef CONFIG_PM_SLEEP 719 .freeze = virtballoon_freeze, 720 .restore = virtballoon_restore, 721 #endif 722 }; 723 724 module_virtio_driver(virtio_balloon_driver); 725 MODULE_DEVICE_TABLE(virtio, id_table); 726 MODULE_DESCRIPTION("Virtio balloon driver"); 727 MODULE_LICENSE("GPL"); 728