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 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 OOM_VBALLOON_DEFAULT_PAGES 256 43 #define VIRTBALLOON_OOM_NOTIFY_PRIORITY 80 44 45 static int oom_pages = OOM_VBALLOON_DEFAULT_PAGES; 46 module_param(oom_pages, int, S_IRUSR | S_IWUSR); 47 MODULE_PARM_DESC(oom_pages, "pages to free on OOM"); 48 49 #ifdef CONFIG_BALLOON_COMPACTION 50 static struct vfsmount *balloon_mnt; 51 #endif 52 53 struct virtio_balloon { 54 struct virtio_device *vdev; 55 struct virtqueue *inflate_vq, *deflate_vq, *stats_vq; 56 57 /* The balloon servicing is delegated to a freezable workqueue. */ 58 struct work_struct update_balloon_stats_work; 59 struct work_struct update_balloon_size_work; 60 61 /* Prevent updating balloon when it is being canceled. */ 62 spinlock_t stop_update_lock; 63 bool stop_update; 64 65 /* Waiting for host to ack the pages we released. */ 66 wait_queue_head_t acked; 67 68 /* Number of balloon pages we've told the Host we're not using. */ 69 unsigned int num_pages; 70 /* 71 * The pages we've told the Host we're not using are enqueued 72 * at vb_dev_info->pages list. 73 * Each page on this list adds VIRTIO_BALLOON_PAGES_PER_PAGE 74 * to num_pages above. 75 */ 76 struct balloon_dev_info vb_dev_info; 77 78 /* Synchronize access/update to this struct virtio_balloon elements */ 79 struct mutex balloon_lock; 80 81 /* The array of pfns we tell the Host about. */ 82 unsigned int num_pfns; 83 __virtio32 pfns[VIRTIO_BALLOON_ARRAY_PFNS_MAX]; 84 85 /* Memory statistics */ 86 struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR]; 87 88 /* To register callback in oom notifier call chain */ 89 struct notifier_block nb; 90 }; 91 92 static struct virtio_device_id id_table[] = { 93 { VIRTIO_ID_BALLOON, VIRTIO_DEV_ANY_ID }, 94 { 0 }, 95 }; 96 97 static u32 page_to_balloon_pfn(struct page *page) 98 { 99 unsigned long pfn = page_to_pfn(page); 100 101 BUILD_BUG_ON(PAGE_SHIFT < VIRTIO_BALLOON_PFN_SHIFT); 102 /* Convert pfn from Linux page size to balloon page size. */ 103 return pfn * VIRTIO_BALLOON_PAGES_PER_PAGE; 104 } 105 106 static struct page *balloon_pfn_to_page(u32 pfn) 107 { 108 BUG_ON(pfn % VIRTIO_BALLOON_PAGES_PER_PAGE); 109 return pfn_to_page(pfn / VIRTIO_BALLOON_PAGES_PER_PAGE); 110 } 111 112 static void balloon_ack(struct virtqueue *vq) 113 { 114 struct virtio_balloon *vb = vq->vdev->priv; 115 116 wake_up(&vb->acked); 117 } 118 119 static void tell_host(struct virtio_balloon *vb, struct virtqueue *vq) 120 { 121 struct scatterlist sg; 122 unsigned int len; 123 124 sg_init_one(&sg, vb->pfns, sizeof(vb->pfns[0]) * vb->num_pfns); 125 126 /* We should always be able to add one buffer to an empty queue. */ 127 virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL); 128 virtqueue_kick(vq); 129 130 /* When host has read buffer, this completes via balloon_ack */ 131 wait_event(vb->acked, virtqueue_get_buf(vq, &len)); 132 133 } 134 135 static void set_page_pfns(struct virtio_balloon *vb, 136 __virtio32 pfns[], struct page *page) 137 { 138 unsigned int i; 139 140 /* Set balloon pfns pointing at this page. 141 * Note that the first pfn points at start of the page. */ 142 for (i = 0; i < VIRTIO_BALLOON_PAGES_PER_PAGE; i++) 143 pfns[i] = cpu_to_virtio32(vb->vdev, 144 page_to_balloon_pfn(page) + i); 145 } 146 147 static unsigned fill_balloon(struct virtio_balloon *vb, size_t num) 148 { 149 struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info; 150 unsigned num_allocated_pages; 151 152 /* We can only do one array worth at a time. */ 153 num = min(num, ARRAY_SIZE(vb->pfns)); 154 155 mutex_lock(&vb->balloon_lock); 156 for (vb->num_pfns = 0; vb->num_pfns < num; 157 vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) { 158 struct page *page = balloon_page_enqueue(vb_dev_info); 159 160 if (!page) { 161 dev_info_ratelimited(&vb->vdev->dev, 162 "Out of puff! Can't get %u pages\n", 163 VIRTIO_BALLOON_PAGES_PER_PAGE); 164 /* Sleep for at least 1/5 of a second before retry. */ 165 msleep(200); 166 break; 167 } 168 set_page_pfns(vb, vb->pfns + vb->num_pfns, page); 169 vb->num_pages += VIRTIO_BALLOON_PAGES_PER_PAGE; 170 if (!virtio_has_feature(vb->vdev, 171 VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) 172 adjust_managed_page_count(page, -1); 173 } 174 175 num_allocated_pages = vb->num_pfns; 176 /* Did we get any? */ 177 if (vb->num_pfns != 0) 178 tell_host(vb, vb->inflate_vq); 179 mutex_unlock(&vb->balloon_lock); 180 181 return num_allocated_pages; 182 } 183 184 static void release_pages_balloon(struct virtio_balloon *vb) 185 { 186 unsigned int i; 187 struct page *page; 188 189 /* Find pfns pointing at start of each page, get pages and free them. */ 190 for (i = 0; i < vb->num_pfns; i += VIRTIO_BALLOON_PAGES_PER_PAGE) { 191 page = balloon_pfn_to_page(virtio32_to_cpu(vb->vdev, 192 vb->pfns[i])); 193 if (!virtio_has_feature(vb->vdev, 194 VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) 195 adjust_managed_page_count(page, 1); 196 put_page(page); /* balloon reference */ 197 } 198 } 199 200 static unsigned leak_balloon(struct virtio_balloon *vb, size_t num) 201 { 202 unsigned num_freed_pages; 203 struct page *page; 204 struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info; 205 206 /* We can only do one array worth at a time. */ 207 num = min(num, ARRAY_SIZE(vb->pfns)); 208 209 mutex_lock(&vb->balloon_lock); 210 for (vb->num_pfns = 0; vb->num_pfns < num; 211 vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) { 212 page = balloon_page_dequeue(vb_dev_info); 213 if (!page) 214 break; 215 set_page_pfns(vb, vb->pfns + vb->num_pfns, page); 216 vb->num_pages -= VIRTIO_BALLOON_PAGES_PER_PAGE; 217 } 218 219 num_freed_pages = vb->num_pfns; 220 /* 221 * Note that if 222 * virtio_has_feature(vdev, VIRTIO_BALLOON_F_MUST_TELL_HOST); 223 * is true, we *have* to do it in this order 224 */ 225 if (vb->num_pfns != 0) 226 tell_host(vb, vb->deflate_vq); 227 release_pages_balloon(vb); 228 mutex_unlock(&vb->balloon_lock); 229 return num_freed_pages; 230 } 231 232 static inline void update_stat(struct virtio_balloon *vb, int idx, 233 u16 tag, u64 val) 234 { 235 BUG_ON(idx >= VIRTIO_BALLOON_S_NR); 236 vb->stats[idx].tag = cpu_to_virtio16(vb->vdev, tag); 237 vb->stats[idx].val = cpu_to_virtio64(vb->vdev, val); 238 } 239 240 #define pages_to_bytes(x) ((u64)(x) << PAGE_SHIFT) 241 242 static void update_balloon_stats(struct virtio_balloon *vb) 243 { 244 unsigned long events[NR_VM_EVENT_ITEMS]; 245 struct sysinfo i; 246 int idx = 0; 247 long available; 248 249 all_vm_events(events); 250 si_meminfo(&i); 251 252 available = si_mem_available(); 253 254 update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_IN, 255 pages_to_bytes(events[PSWPIN])); 256 update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_OUT, 257 pages_to_bytes(events[PSWPOUT])); 258 update_stat(vb, idx++, VIRTIO_BALLOON_S_MAJFLT, events[PGMAJFAULT]); 259 update_stat(vb, idx++, VIRTIO_BALLOON_S_MINFLT, events[PGFAULT]); 260 update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMFREE, 261 pages_to_bytes(i.freeram)); 262 update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMTOT, 263 pages_to_bytes(i.totalram)); 264 update_stat(vb, idx++, VIRTIO_BALLOON_S_AVAIL, 265 pages_to_bytes(available)); 266 } 267 268 /* 269 * While most virtqueues communicate guest-initiated requests to the hypervisor, 270 * the stats queue operates in reverse. The driver initializes the virtqueue 271 * with a single buffer. From that point forward, all conversations consist of 272 * a hypervisor request (a call to this function) which directs us to refill 273 * the virtqueue with a fresh stats buffer. Since stats collection can sleep, 274 * we delegate the job to a freezable workqueue that will do the actual work via 275 * stats_handle_request(). 276 */ 277 static void stats_request(struct virtqueue *vq) 278 { 279 struct virtio_balloon *vb = vq->vdev->priv; 280 281 spin_lock(&vb->stop_update_lock); 282 if (!vb->stop_update) 283 queue_work(system_freezable_wq, &vb->update_balloon_stats_work); 284 spin_unlock(&vb->stop_update_lock); 285 } 286 287 static void stats_handle_request(struct virtio_balloon *vb) 288 { 289 struct virtqueue *vq; 290 struct scatterlist sg; 291 unsigned int len; 292 293 update_balloon_stats(vb); 294 295 vq = vb->stats_vq; 296 if (!virtqueue_get_buf(vq, &len)) 297 return; 298 sg_init_one(&sg, vb->stats, sizeof(vb->stats)); 299 virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL); 300 virtqueue_kick(vq); 301 } 302 303 static void virtballoon_changed(struct virtio_device *vdev) 304 { 305 struct virtio_balloon *vb = vdev->priv; 306 unsigned long flags; 307 308 spin_lock_irqsave(&vb->stop_update_lock, flags); 309 if (!vb->stop_update) 310 queue_work(system_freezable_wq, &vb->update_balloon_size_work); 311 spin_unlock_irqrestore(&vb->stop_update_lock, flags); 312 } 313 314 static inline s64 towards_target(struct virtio_balloon *vb) 315 { 316 s64 target; 317 u32 num_pages; 318 319 virtio_cread(vb->vdev, struct virtio_balloon_config, num_pages, 320 &num_pages); 321 322 /* Legacy balloon config space is LE, unlike all other devices. */ 323 if (!virtio_has_feature(vb->vdev, VIRTIO_F_VERSION_1)) 324 num_pages = le32_to_cpu((__force __le32)num_pages); 325 326 target = num_pages; 327 return target - vb->num_pages; 328 } 329 330 static void update_balloon_size(struct virtio_balloon *vb) 331 { 332 u32 actual = vb->num_pages; 333 334 /* Legacy balloon config space is LE, unlike all other devices. */ 335 if (!virtio_has_feature(vb->vdev, VIRTIO_F_VERSION_1)) 336 actual = (__force u32)cpu_to_le32(actual); 337 338 virtio_cwrite(vb->vdev, struct virtio_balloon_config, actual, 339 &actual); 340 } 341 342 /* 343 * virtballoon_oom_notify - release pages when system is under severe 344 * memory pressure (called from out_of_memory()) 345 * @self : notifier block struct 346 * @dummy: not used 347 * @parm : returned - number of freed pages 348 * 349 * The balancing of memory by use of the virtio balloon should not cause 350 * the termination of processes while there are pages in the balloon. 351 * If virtio balloon manages to release some memory, it will make the 352 * system return and retry the allocation that forced the OOM killer 353 * to run. 354 */ 355 static int virtballoon_oom_notify(struct notifier_block *self, 356 unsigned long dummy, void *parm) 357 { 358 struct virtio_balloon *vb; 359 unsigned long *freed; 360 unsigned num_freed_pages; 361 362 vb = container_of(self, struct virtio_balloon, nb); 363 if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) 364 return NOTIFY_OK; 365 366 freed = parm; 367 num_freed_pages = leak_balloon(vb, oom_pages); 368 update_balloon_size(vb); 369 *freed += num_freed_pages; 370 371 return NOTIFY_OK; 372 } 373 374 static void update_balloon_stats_func(struct work_struct *work) 375 { 376 struct virtio_balloon *vb; 377 378 vb = container_of(work, struct virtio_balloon, 379 update_balloon_stats_work); 380 stats_handle_request(vb); 381 } 382 383 static void update_balloon_size_func(struct work_struct *work) 384 { 385 struct virtio_balloon *vb; 386 s64 diff; 387 388 vb = container_of(work, struct virtio_balloon, 389 update_balloon_size_work); 390 diff = towards_target(vb); 391 392 if (diff > 0) 393 diff -= fill_balloon(vb, diff); 394 else if (diff < 0) 395 diff += leak_balloon(vb, -diff); 396 update_balloon_size(vb); 397 398 if (diff) 399 queue_work(system_freezable_wq, work); 400 } 401 402 static int init_vqs(struct virtio_balloon *vb) 403 { 404 struct virtqueue *vqs[3]; 405 vq_callback_t *callbacks[] = { balloon_ack, balloon_ack, stats_request }; 406 static const char * const names[] = { "inflate", "deflate", "stats" }; 407 int err, nvqs; 408 409 /* 410 * We expect two virtqueues: inflate and deflate, and 411 * optionally stat. 412 */ 413 nvqs = virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ) ? 3 : 2; 414 err = vb->vdev->config->find_vqs(vb->vdev, nvqs, vqs, callbacks, names); 415 if (err) 416 return err; 417 418 vb->inflate_vq = vqs[0]; 419 vb->deflate_vq = vqs[1]; 420 if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) { 421 struct scatterlist sg; 422 vb->stats_vq = vqs[2]; 423 424 /* 425 * Prime this virtqueue with one buffer so the hypervisor can 426 * use it to signal us later (it can't be broken yet!). 427 */ 428 sg_init_one(&sg, vb->stats, sizeof vb->stats); 429 if (virtqueue_add_outbuf(vb->stats_vq, &sg, 1, vb, GFP_KERNEL) 430 < 0) 431 BUG(); 432 virtqueue_kick(vb->stats_vq); 433 } 434 return 0; 435 } 436 437 #ifdef CONFIG_BALLOON_COMPACTION 438 /* 439 * virtballoon_migratepage - perform the balloon page migration on behalf of 440 * a compation thread. (called under page lock) 441 * @vb_dev_info: the balloon device 442 * @newpage: page that will replace the isolated page after migration finishes. 443 * @page : the isolated (old) page that is about to be migrated to newpage. 444 * @mode : compaction mode -- not used for balloon page migration. 445 * 446 * After a ballooned page gets isolated by compaction procedures, this is the 447 * function that performs the page migration on behalf of a compaction thread 448 * The page migration for virtio balloon is done in a simple swap fashion which 449 * follows these two macro steps: 450 * 1) insert newpage into vb->pages list and update the host about it; 451 * 2) update the host about the old page removed from vb->pages list; 452 * 453 * This function preforms the balloon page migration task. 454 * Called through balloon_mapping->a_ops->migratepage 455 */ 456 static int virtballoon_migratepage(struct balloon_dev_info *vb_dev_info, 457 struct page *newpage, struct page *page, enum migrate_mode mode) 458 { 459 struct virtio_balloon *vb = container_of(vb_dev_info, 460 struct virtio_balloon, vb_dev_info); 461 unsigned long flags; 462 463 /* 464 * In order to avoid lock contention while migrating pages concurrently 465 * to leak_balloon() or fill_balloon() we just give up the balloon_lock 466 * this turn, as it is easier to retry the page migration later. 467 * This also prevents fill_balloon() getting stuck into a mutex 468 * recursion in the case it ends up triggering memory compaction 469 * while it is attempting to inflate the ballon. 470 */ 471 if (!mutex_trylock(&vb->balloon_lock)) 472 return -EAGAIN; 473 474 get_page(newpage); /* balloon reference */ 475 476 /* balloon's page migration 1st step -- inflate "newpage" */ 477 spin_lock_irqsave(&vb_dev_info->pages_lock, flags); 478 balloon_page_insert(vb_dev_info, newpage); 479 vb_dev_info->isolated_pages--; 480 __count_vm_event(BALLOON_MIGRATE); 481 spin_unlock_irqrestore(&vb_dev_info->pages_lock, flags); 482 vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE; 483 set_page_pfns(vb, vb->pfns, newpage); 484 tell_host(vb, vb->inflate_vq); 485 486 /* balloon's page migration 2nd step -- deflate "page" */ 487 balloon_page_delete(page); 488 vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE; 489 set_page_pfns(vb, vb->pfns, page); 490 tell_host(vb, vb->deflate_vq); 491 492 mutex_unlock(&vb->balloon_lock); 493 494 put_page(page); /* balloon reference */ 495 496 return MIGRATEPAGE_SUCCESS; 497 } 498 499 static struct dentry *balloon_mount(struct file_system_type *fs_type, 500 int flags, const char *dev_name, void *data) 501 { 502 static const struct dentry_operations ops = { 503 .d_dname = simple_dname, 504 }; 505 506 return mount_pseudo(fs_type, "balloon-kvm:", NULL, &ops, 507 BALLOON_KVM_MAGIC); 508 } 509 510 static struct file_system_type balloon_fs = { 511 .name = "balloon-kvm", 512 .mount = balloon_mount, 513 .kill_sb = kill_anon_super, 514 }; 515 516 #endif /* CONFIG_BALLOON_COMPACTION */ 517 518 static int virtballoon_probe(struct virtio_device *vdev) 519 { 520 struct virtio_balloon *vb; 521 int err; 522 523 if (!vdev->config->get) { 524 dev_err(&vdev->dev, "%s failure: config access disabled\n", 525 __func__); 526 return -EINVAL; 527 } 528 529 vdev->priv = vb = kmalloc(sizeof(*vb), GFP_KERNEL); 530 if (!vb) { 531 err = -ENOMEM; 532 goto out; 533 } 534 535 INIT_WORK(&vb->update_balloon_stats_work, update_balloon_stats_func); 536 INIT_WORK(&vb->update_balloon_size_work, update_balloon_size_func); 537 spin_lock_init(&vb->stop_update_lock); 538 vb->stop_update = false; 539 vb->num_pages = 0; 540 mutex_init(&vb->balloon_lock); 541 init_waitqueue_head(&vb->acked); 542 vb->vdev = vdev; 543 544 balloon_devinfo_init(&vb->vb_dev_info); 545 546 err = init_vqs(vb); 547 if (err) 548 goto out_free_vb; 549 550 vb->nb.notifier_call = virtballoon_oom_notify; 551 vb->nb.priority = VIRTBALLOON_OOM_NOTIFY_PRIORITY; 552 err = register_oom_notifier(&vb->nb); 553 if (err < 0) 554 goto out_del_vqs; 555 556 #ifdef CONFIG_BALLOON_COMPACTION 557 balloon_mnt = kern_mount(&balloon_fs); 558 if (IS_ERR(balloon_mnt)) { 559 err = PTR_ERR(balloon_mnt); 560 unregister_oom_notifier(&vb->nb); 561 goto out_del_vqs; 562 } 563 564 vb->vb_dev_info.migratepage = virtballoon_migratepage; 565 vb->vb_dev_info.inode = alloc_anon_inode(balloon_mnt->mnt_sb); 566 if (IS_ERR(vb->vb_dev_info.inode)) { 567 err = PTR_ERR(vb->vb_dev_info.inode); 568 kern_unmount(balloon_mnt); 569 unregister_oom_notifier(&vb->nb); 570 vb->vb_dev_info.inode = NULL; 571 goto out_del_vqs; 572 } 573 vb->vb_dev_info.inode->i_mapping->a_ops = &balloon_aops; 574 #endif 575 576 virtio_device_ready(vdev); 577 578 return 0; 579 580 out_del_vqs: 581 vdev->config->del_vqs(vdev); 582 out_free_vb: 583 kfree(vb); 584 out: 585 return err; 586 } 587 588 static void remove_common(struct virtio_balloon *vb) 589 { 590 /* There might be pages left in the balloon: free them. */ 591 while (vb->num_pages) 592 leak_balloon(vb, vb->num_pages); 593 update_balloon_size(vb); 594 595 /* Now we reset the device so we can clean up the queues. */ 596 vb->vdev->config->reset(vb->vdev); 597 598 vb->vdev->config->del_vqs(vb->vdev); 599 } 600 601 static void virtballoon_remove(struct virtio_device *vdev) 602 { 603 struct virtio_balloon *vb = vdev->priv; 604 605 unregister_oom_notifier(&vb->nb); 606 607 spin_lock_irq(&vb->stop_update_lock); 608 vb->stop_update = true; 609 spin_unlock_irq(&vb->stop_update_lock); 610 cancel_work_sync(&vb->update_balloon_size_work); 611 cancel_work_sync(&vb->update_balloon_stats_work); 612 613 remove_common(vb); 614 if (vb->vb_dev_info.inode) 615 iput(vb->vb_dev_info.inode); 616 kfree(vb); 617 } 618 619 #ifdef CONFIG_PM_SLEEP 620 static int virtballoon_freeze(struct virtio_device *vdev) 621 { 622 struct virtio_balloon *vb = vdev->priv; 623 624 /* 625 * The workqueue is already frozen by the PM core before this 626 * function is called. 627 */ 628 remove_common(vb); 629 return 0; 630 } 631 632 static int virtballoon_restore(struct virtio_device *vdev) 633 { 634 struct virtio_balloon *vb = vdev->priv; 635 int ret; 636 637 ret = init_vqs(vdev->priv); 638 if (ret) 639 return ret; 640 641 virtio_device_ready(vdev); 642 643 if (towards_target(vb)) 644 virtballoon_changed(vdev); 645 update_balloon_size(vb); 646 return 0; 647 } 648 #endif 649 650 static unsigned int features[] = { 651 VIRTIO_BALLOON_F_MUST_TELL_HOST, 652 VIRTIO_BALLOON_F_STATS_VQ, 653 VIRTIO_BALLOON_F_DEFLATE_ON_OOM, 654 }; 655 656 static struct virtio_driver virtio_balloon_driver = { 657 .feature_table = features, 658 .feature_table_size = ARRAY_SIZE(features), 659 .driver.name = KBUILD_MODNAME, 660 .driver.owner = THIS_MODULE, 661 .id_table = id_table, 662 .probe = virtballoon_probe, 663 .remove = virtballoon_remove, 664 .config_changed = virtballoon_changed, 665 #ifdef CONFIG_PM_SLEEP 666 .freeze = virtballoon_freeze, 667 .restore = virtballoon_restore, 668 #endif 669 }; 670 671 module_virtio_driver(virtio_balloon_driver); 672 MODULE_DEVICE_TABLE(virtio, id_table); 673 MODULE_DESCRIPTION("Virtio balloon driver"); 674 MODULE_LICENSE("GPL"); 675