drivers/vhost/vhost.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* Copyright (C) 2009 Red Hat, Inc.
   3  * Copyright (C) 2006 Rusty Russell IBM Corporation
   4  *
   5  * Author: Michael S. Tsirkin <mst@redhat.com>
   6  *
   7  * Inspiration, some code, and most witty comments come from
   8  * Documentation/virtual/lguest/lguest.c, by Rusty Russell
   9  *
  10  * Generic code for virtio server in host kernel.
  11  */
  12
  13 #include <linux/eventfd.h>
  14 #include <linux/vhost.h>
  15 #include <linux/uio.h>
  16 #include <linux/mm.h>
  17 #include <linux/miscdevice.h>
  18 #include <linux/mutex.h>
  19 #include <linux/poll.h>
  20 #include <linux/file.h>
  21 #include <linux/highmem.h>
  22 #include <linux/slab.h>
  23 #include <linux/vmalloc.h>
  24 #include <linux/kthread.h>
  25 #include <linux/module.h>
  26 #include <linux/sort.h>
  27 #include <linux/sched/mm.h>
  28 #include <linux/sched/signal.h>
  29 #include <linux/sched/vhost_task.h>
  30 #include <linux/interval_tree_generic.h>
  31 #include <linux/nospec.h>
  32 #include <linux/kcov.h>
  33
  34 #include "vhost.h"
  35
  36 static ushort max_mem_regions = 64;
  37 module_param(max_mem_regions, ushort, 0444);
  38 MODULE_PARM_DESC(max_mem_regions,
  39         "Maximum number of memory regions in memory map. (default: 64)");
  40 static int max_iotlb_entries = 2048;
  41 module_param(max_iotlb_entries, int, 0444);
  42 MODULE_PARM_DESC(max_iotlb_entries,
  43         "Maximum number of iotlb entries. (default: 2048)");
  44
  45 enum {
  46         VHOST_MEMORY_F_LOG = 0x1,
  47 };
  48
  49 #define vhost_used_event(vq) ((__virtio16 __user *)&vq->avail->ring[vq->num])
  50 #define vhost_avail_event(vq) ((__virtio16 __user *)&vq->used->ring[vq->num])
  51
  52 #ifdef CONFIG_VHOST_CROSS_ENDIAN_LEGACY
  53 static void vhost_disable_cross_endian(struct vhost_virtqueue *vq)
  54 {
  55         vq->user_be = !virtio_legacy_is_little_endian();
  56 }
  57
  58 static void vhost_enable_cross_endian_big(struct vhost_virtqueue *vq)
  59 {
  60         vq->user_be = true;
  61 }
  62
  63 static void vhost_enable_cross_endian_little(struct vhost_virtqueue *vq)
  64 {
  65         vq->user_be = false;
  66 }
  67
  68 static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp)
  69 {
  70         struct vhost_vring_state s;
  71
  72         if (vq->private_data)
  73                 return -EBUSY;
  74
  75         if (copy_from_user(&s, argp, sizeof(s)))
  76                 return -EFAULT;
  77
  78         if (s.num != VHOST_VRING_LITTLE_ENDIAN &&
  79             s.num != VHOST_VRING_BIG_ENDIAN)
  80                 return -EINVAL;
  81
  82         if (s.num == VHOST_VRING_BIG_ENDIAN)
  83                 vhost_enable_cross_endian_big(vq);
  84         else
  85                 vhost_enable_cross_endian_little(vq);
  86
  87         return 0;
  88 }
  89
  90 static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx,
  91                                    int __user *argp)
  92 {
  93         struct vhost_vring_state s = {
  94                 .index = idx,
  95                 .num = vq->user_be
  96         };
  97
  98         if (copy_to_user(argp, &s, sizeof(s)))
  99                 return -EFAULT;
 100
 101         return 0;
 102 }
 103
 104 static void vhost_init_is_le(struct vhost_virtqueue *vq)
 105 {
 106         /* Note for legacy virtio: user_be is initialized at reset time
 107          * according to the host endianness. If userspace does not set an
 108          * explicit endianness, the default behavior is native endian, as
 109          * expected by legacy virtio.
 110          */
 111         vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1) || !vq->user_be;
 112 }
 113 #else
 114 static void vhost_disable_cross_endian(struct vhost_virtqueue *vq)
 115 {
 116 }
 117
 118 static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp)
 119 {
 120         return -ENOIOCTLCMD;
 121 }
 122
 123 static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx,
 124                                    int __user *argp)
 125 {
 126         return -ENOIOCTLCMD;
 127 }
 128
 129 static void vhost_init_is_le(struct vhost_virtqueue *vq)
 130 {
 131         vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1)
 132                 || virtio_legacy_is_little_endian();
 133 }
 134 #endif /* CONFIG_VHOST_CROSS_ENDIAN_LEGACY */
 135
 136 static void vhost_reset_is_le(struct vhost_virtqueue *vq)
 137 {
 138         vhost_init_is_le(vq);
 139 }
 140
 141 struct vhost_flush_struct {
 142         struct vhost_work work;
 143         struct completion wait_event;
 144 };
 145
 146 static void vhost_flush_work(struct vhost_work *work)
 147 {
 148         struct vhost_flush_struct *s;
 149
 150         s = container_of(work, struct vhost_flush_struct, work);
 151         complete(&s->wait_event);
 152 }
 153
 154 static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh,
 155                             poll_table *pt)
 156 {
 157         struct vhost_poll *poll;
 158
 159         poll = container_of(pt, struct vhost_poll, table);
 160         poll->wqh = wqh;
 161         add_wait_queue(wqh, &poll->wait);
 162 }
 163
 164 static int vhost_poll_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync,
 165                              void *key)
 166 {
 167         struct vhost_poll *poll = container_of(wait, struct vhost_poll, wait);
 168         struct vhost_work *work = &poll->work;
 169
 170         if (!(key_to_poll(key) & poll->mask))
 171                 return 0;
 172
 173         if (!poll->dev->use_worker)
 174                 work->fn(work);
 175         else
 176                 vhost_poll_queue(poll);
 177
 178         return 0;
 179 }
 180
 181 void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn)
 182 {
 183         clear_bit(VHOST_WORK_QUEUED, &work->flags);
 184         work->fn = fn;
 185 }
 186 EXPORT_SYMBOL_GPL(vhost_work_init);
 187
 188 /* Init poll structure */
 189 void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
 190                      __poll_t mask, struct vhost_dev *dev)
 191 {
 192         init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup);
 193         init_poll_funcptr(&poll->table, vhost_poll_func);
 194         poll->mask = mask;
 195         poll->dev = dev;
 196         poll->wqh = NULL;
 197
 198         vhost_work_init(&poll->work, fn);
 199 }
 200 EXPORT_SYMBOL_GPL(vhost_poll_init);
 201
 202 /* Start polling a file. We add ourselves to file's wait queue. The caller must
 203  * keep a reference to a file until after vhost_poll_stop is called. */
 204 int vhost_poll_start(struct vhost_poll *poll, struct file *file)
 205 {
 206         __poll_t mask;
 207
 208         if (poll->wqh)
 209                 return 0;
 210
 211         mask = vfs_poll(file, &poll->table);
 212         if (mask)
 213                 vhost_poll_wakeup(&poll->wait, 0, 0, poll_to_key(mask));
 214         if (mask & EPOLLERR) {
 215                 vhost_poll_stop(poll);
 216                 return -EINVAL;
 217         }
 218
 219         return 0;
 220 }
 221 EXPORT_SYMBOL_GPL(vhost_poll_start);
 222
 223 /* Stop polling a file. After this function returns, it becomes safe to drop the
 224  * file reference. You must also flush afterwards. */
 225 void vhost_poll_stop(struct vhost_poll *poll)
 226 {
 227         if (poll->wqh) {
 228                 remove_wait_queue(poll->wqh, &poll->wait);
 229                 poll->wqh = NULL;
 230         }
 231 }
 232 EXPORT_SYMBOL_GPL(vhost_poll_stop);
 233
 234 void vhost_dev_flush(struct vhost_dev *dev)
 235 {
 236         struct vhost_flush_struct flush;
 237
 238         if (dev->worker) {
 239                 init_completion(&flush.wait_event);
 240                 vhost_work_init(&flush.work, vhost_flush_work);
 241
 242                 vhost_work_queue(dev, &flush.work);
 243                 wait_for_completion(&flush.wait_event);
 244         }
 245 }
 246 EXPORT_SYMBOL_GPL(vhost_dev_flush);
 247
 248 void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work)
 249 {
 250         if (!dev->worker)
 251                 return;
 252
 253         if (!test_and_set_bit(VHOST_WORK_QUEUED, &work->flags)) {
 254                 /* We can only add the work to the list after we're
 255                  * sure it was not in the list.
 256                  * test_and_set_bit() implies a memory barrier.
 257                  */
 258                 llist_add(&work->node, &dev->worker->work_list);
 259                 wake_up_process(dev->worker->vtsk->task);
 260         }
 261 }
 262 EXPORT_SYMBOL_GPL(vhost_work_queue);
 263
 264 /* A lockless hint for busy polling code to exit the loop */
 265 bool vhost_has_work(struct vhost_dev *dev)
 266 {
 267         return dev->worker && !llist_empty(&dev->worker->work_list);
 268 }
 269 EXPORT_SYMBOL_GPL(vhost_has_work);
 270
 271 void vhost_poll_queue(struct vhost_poll *poll)
 272 {
 273         vhost_work_queue(poll->dev, &poll->work);
 274 }
 275 EXPORT_SYMBOL_GPL(vhost_poll_queue);
 276
 277 static void __vhost_vq_meta_reset(struct vhost_virtqueue *vq)
 278 {
 279         int j;
 280
 281         for (j = 0; j < VHOST_NUM_ADDRS; j++)
 282                 vq->meta_iotlb[j] = NULL;
 283 }
 284
 285 static void vhost_vq_meta_reset(struct vhost_dev *d)
 286 {
 287         int i;
 288
 289         for (i = 0; i < d->nvqs; ++i)
 290                 __vhost_vq_meta_reset(d->vqs[i]);
 291 }
 292
 293 static void vhost_vring_call_reset(struct vhost_vring_call *call_ctx)
 294 {
 295         call_ctx->ctx = NULL;
 296         memset(&call_ctx->producer, 0x0, sizeof(struct irq_bypass_producer));
 297 }
 298
 299 bool vhost_vq_is_setup(struct vhost_virtqueue *vq)
 300 {
 301         return vq->avail && vq->desc && vq->used && vhost_vq_access_ok(vq);
 302 }
 303 EXPORT_SYMBOL_GPL(vhost_vq_is_setup);
 304
 305 static void vhost_vq_reset(struct vhost_dev *dev,
 306                            struct vhost_virtqueue *vq)
 307 {
 308         vq->num = 1;
 309         vq->desc = NULL;
 310         vq->avail = NULL;
 311         vq->used = NULL;
 312         vq->last_avail_idx = 0;
 313         vq->avail_idx = 0;
 314         vq->last_used_idx = 0;
 315         vq->signalled_used = 0;
 316         vq->signalled_used_valid = false;
 317         vq->used_flags = 0;
 318         vq->log_used = false;
 319         vq->log_addr = -1ull;
 320         vq->private_data = NULL;
 321         vq->acked_features = 0;
 322         vq->acked_backend_features = 0;
 323         vq->log_base = NULL;
 324         vq->error_ctx = NULL;
 325         vq->kick = NULL;
 326         vq->log_ctx = NULL;
 327         vhost_disable_cross_endian(vq);
 328         vhost_reset_is_le(vq);
 329         vq->busyloop_timeout = 0;
 330         vq->umem = NULL;
 331         vq->iotlb = NULL;
 332         vhost_vring_call_reset(&vq->call_ctx);
 333         __vhost_vq_meta_reset(vq);
 334 }
 335
 336 static int vhost_worker(void *data)
 337 {
 338         struct vhost_worker *worker = data;
 339         struct vhost_work *work, *work_next;
 340         struct llist_node *node;
 341
 342         for (;;) {
 343                 /* mb paired w/ kthread_stop */
 344                 set_current_state(TASK_INTERRUPTIBLE);
 345
 346                 if (vhost_task_should_stop(worker->vtsk)) {
 347                         __set_current_state(TASK_RUNNING);
 348                         break;
 349                 }
 350
 351                 node = llist_del_all(&worker->work_list);
 352                 if (!node)
 353                         schedule();
 354
 355                 node = llist_reverse_order(node);
 356                 /* make sure flag is seen after deletion */
 357                 smp_wmb();
 358                 llist_for_each_entry_safe(work, work_next, node, node) {
 359                         clear_bit(VHOST_WORK_QUEUED, &work->flags);
 360                         __set_current_state(TASK_RUNNING);
 361                         kcov_remote_start_common(worker->kcov_handle);
 362                         work->fn(work);
 363                         kcov_remote_stop();
 364                         if (need_resched())
 365                                 schedule();
 366                 }
 367         }
 368
 369         return 0;
 370 }
 371
 372 static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq)
 373 {
 374         kfree(vq->indirect);
 375         vq->indirect = NULL;
 376         kfree(vq->log);
 377         vq->log = NULL;
 378         kfree(vq->heads);
 379         vq->heads = NULL;
 380 }
 381
 382 /* Helper to allocate iovec buffers for all vqs. */
 383 static long vhost_dev_alloc_iovecs(struct vhost_dev *dev)
 384 {
 385         struct vhost_virtqueue *vq;
 386         int i;
 387
 388         for (i = 0; i < dev->nvqs; ++i) {
 389                 vq = dev->vqs[i];
 390                 vq->indirect = kmalloc_array(UIO_MAXIOV,
 391                                              sizeof(*vq->indirect),
 392                                              GFP_KERNEL);
 393                 vq->log = kmalloc_array(dev->iov_limit, sizeof(*vq->log),
 394                                         GFP_KERNEL);
 395                 vq->heads = kmalloc_array(dev->iov_limit, sizeof(*vq->heads),
 396                                           GFP_KERNEL);
 397                 if (!vq->indirect || !vq->log || !vq->heads)
 398                         goto err_nomem;
 399         }
 400         return 0;
 401
 402 err_nomem:
 403         for (; i >= 0; --i)
 404                 vhost_vq_free_iovecs(dev->vqs[i]);
 405         return -ENOMEM;
 406 }
 407
 408 static void vhost_dev_free_iovecs(struct vhost_dev *dev)
 409 {
 410         int i;
 411
 412         for (i = 0; i < dev->nvqs; ++i)
 413                 vhost_vq_free_iovecs(dev->vqs[i]);
 414 }
 415
 416 bool vhost_exceeds_weight(struct vhost_virtqueue *vq,
 417                           int pkts, int total_len)
 418 {
 419         struct vhost_dev *dev = vq->dev;
 420
 421         if ((dev->byte_weight && total_len >= dev->byte_weight) ||
 422             pkts >= dev->weight) {
 423                 vhost_poll_queue(&vq->poll);
 424                 return true;
 425         }
 426
 427         return false;
 428 }
 429 EXPORT_SYMBOL_GPL(vhost_exceeds_weight);
 430
 431 static size_t vhost_get_avail_size(struct vhost_virtqueue *vq,
 432                                    unsigned int num)
 433 {
 434         size_t event __maybe_unused =
 435                vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
 436
 437         return sizeof(*vq->avail) +
 438                sizeof(*vq->avail->ring) * num + event;
 439 }
 440
 441 static size_t vhost_get_used_size(struct vhost_virtqueue *vq,
 442                                   unsigned int num)
 443 {
 444         size_t event __maybe_unused =
 445                vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
 446
 447         return sizeof(*vq->used) +
 448                sizeof(*vq->used->ring) * num + event;
 449 }
 450
 451 static size_t vhost_get_desc_size(struct vhost_virtqueue *vq,
 452                                   unsigned int num)
 453 {
 454         return sizeof(*vq->desc) * num;
 455 }
 456
 457 void vhost_dev_init(struct vhost_dev *dev,
 458                     struct vhost_virtqueue **vqs, int nvqs,
 459                     int iov_limit, int weight, int byte_weight,
 460                     bool use_worker,
 461                     int (*msg_handler)(struct vhost_dev *dev, u32 asid,
 462                                        struct vhost_iotlb_msg *msg))
 463 {
 464         struct vhost_virtqueue *vq;
 465         int i;
 466
 467         dev->vqs = vqs;
 468         dev->nvqs = nvqs;
 469         mutex_init(&dev->mutex);
 470         dev->log_ctx = NULL;
 471         dev->umem = NULL;
 472         dev->iotlb = NULL;
 473         dev->mm = NULL;
 474         dev->worker = NULL;
 475         dev->iov_limit = iov_limit;
 476         dev->weight = weight;
 477         dev->byte_weight = byte_weight;
 478         dev->use_worker = use_worker;
 479         dev->msg_handler = msg_handler;
 480         init_waitqueue_head(&dev->wait);
 481         INIT_LIST_HEAD(&dev->read_list);
 482         INIT_LIST_HEAD(&dev->pending_list);
 483         spin_lock_init(&dev->iotlb_lock);
 484
 485
 486         for (i = 0; i < dev->nvqs; ++i) {
 487                 vq = dev->vqs[i];
 488                 vq->log = NULL;
 489                 vq->indirect = NULL;
 490                 vq->heads = NULL;
 491                 vq->dev = dev;
 492                 mutex_init(&vq->mutex);
 493                 vhost_vq_reset(dev, vq);
 494                 if (vq->handle_kick)
 495                         vhost_poll_init(&vq->poll, vq->handle_kick,
 496                                         EPOLLIN, dev);
 497         }
 498 }
 499 EXPORT_SYMBOL_GPL(vhost_dev_init);
 500
 501 /* Caller should have device mutex */
 502 long vhost_dev_check_owner(struct vhost_dev *dev)
 503 {
 504         /* Are you the owner? If not, I don't think you mean to do that */
 505         return dev->mm == current->mm ? 0 : -EPERM;
 506 }
 507 EXPORT_SYMBOL_GPL(vhost_dev_check_owner);
 508
 509 /* Caller should have device mutex */
 510 bool vhost_dev_has_owner(struct vhost_dev *dev)
 511 {
 512         return dev->mm;
 513 }
 514 EXPORT_SYMBOL_GPL(vhost_dev_has_owner);
 515
 516 static void vhost_attach_mm(struct vhost_dev *dev)
 517 {
 518         /* No owner, become one */
 519         if (dev->use_worker) {
 520                 dev->mm = get_task_mm(current);
 521         } else {
 522                 /* vDPA device does not use worker thead, so there's
 523                  * no need to hold the address space for mm. This help
 524                  * to avoid deadlock in the case of mmap() which may
 525                  * held the refcnt of the file and depends on release
 526                  * method to remove vma.
 527                  */
 528                 dev->mm = current->mm;
 529                 mmgrab(dev->mm);
 530         }
 531 }
 532
 533 static void vhost_detach_mm(struct vhost_dev *dev)
 534 {
 535         if (!dev->mm)
 536                 return;
 537
 538         if (dev->use_worker)
 539                 mmput(dev->mm);
 540         else
 541                 mmdrop(dev->mm);
 542
 543         dev->mm = NULL;
 544 }
 545
 546 static void vhost_worker_free(struct vhost_dev *dev)
 547 {
 548         struct vhost_worker *worker = dev->worker;
 549
 550         if (!worker)
 551                 return;
 552
 553         dev->worker = NULL;
 554         WARN_ON(!llist_empty(&worker->work_list));
 555         vhost_task_stop(worker->vtsk);
 556         kfree(worker);
 557 }
 558
 559 static int vhost_worker_create(struct vhost_dev *dev)
 560 {
 561         struct vhost_worker *worker;
 562         struct vhost_task *vtsk;
 563         char name[TASK_COMM_LEN];
 564         int ret;
 565
 566         worker = kzalloc(sizeof(*worker), GFP_KERNEL_ACCOUNT);
 567         if (!worker)
 568                 return -ENOMEM;
 569
 570         dev->worker = worker;
 571         worker->kcov_handle = kcov_common_handle();
 572         init_llist_head(&worker->work_list);
 573         snprintf(name, sizeof(name), "vhost-%d", current->pid);
 574
 575         vtsk = vhost_task_create(vhost_worker, worker, name);
 576         if (!vtsk) {
 577                 ret = -ENOMEM;
 578                 goto free_worker;
 579         }
 580
 581         worker->vtsk = vtsk;
 582         vhost_task_start(vtsk);
 583         return 0;
 584
 585 free_worker:
 586         kfree(worker);
 587         dev->worker = NULL;
 588         return ret;
 589 }
 590
 591 /* Caller should have device mutex */
 592 long vhost_dev_set_owner(struct vhost_dev *dev)
 593 {
 594         int err;
 595
 596         /* Is there an owner already? */
 597         if (vhost_dev_has_owner(dev)) {
 598                 err = -EBUSY;
 599                 goto err_mm;
 600         }
 601
 602         vhost_attach_mm(dev);
 603
 604         if (dev->use_worker) {
 605                 err = vhost_worker_create(dev);
 606                 if (err)
 607                         goto err_worker;
 608         }
 609
 610         err = vhost_dev_alloc_iovecs(dev);
 611         if (err)
 612                 goto err_iovecs;
 613
 614         return 0;
 615 err_iovecs:
 616         vhost_worker_free(dev);
 617 err_worker:
 618         vhost_detach_mm(dev);
 619 err_mm:
 620         return err;
 621 }
 622 EXPORT_SYMBOL_GPL(vhost_dev_set_owner);
 623
 624 static struct vhost_iotlb *iotlb_alloc(void)
 625 {
 626         return vhost_iotlb_alloc(max_iotlb_entries,
 627                                  VHOST_IOTLB_FLAG_RETIRE);
 628 }
 629
 630 struct vhost_iotlb *vhost_dev_reset_owner_prepare(void)
 631 {
 632         return iotlb_alloc();
 633 }
 634 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner_prepare);
 635
 636 /* Caller should have device mutex */
 637 void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_iotlb *umem)
 638 {
 639         int i;
 640
 641         vhost_dev_cleanup(dev);
 642
 643         dev->umem = umem;
 644         /* We don't need VQ locks below since vhost_dev_cleanup makes sure
 645          * VQs aren't running.
 646          */
 647         for (i = 0; i < dev->nvqs; ++i)
 648                 dev->vqs[i]->umem = umem;
 649 }
 650 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner);
 651
 652 void vhost_dev_stop(struct vhost_dev *dev)
 653 {
 654         int i;
 655
 656         for (i = 0; i < dev->nvqs; ++i) {
 657                 if (dev->vqs[i]->kick && dev->vqs[i]->handle_kick)
 658                         vhost_poll_stop(&dev->vqs[i]->poll);
 659         }
 660
 661         vhost_dev_flush(dev);
 662 }
 663 EXPORT_SYMBOL_GPL(vhost_dev_stop);
 664
 665 void vhost_clear_msg(struct vhost_dev *dev)
 666 {
 667         struct vhost_msg_node *node, *n;
 668
 669         spin_lock(&dev->iotlb_lock);
 670
 671         list_for_each_entry_safe(node, n, &dev->read_list, node) {
 672                 list_del(&node->node);
 673                 kfree(node);
 674         }
 675
 676         list_for_each_entry_safe(node, n, &dev->pending_list, node) {
 677                 list_del(&node->node);
 678                 kfree(node);
 679         }
 680
 681         spin_unlock(&dev->iotlb_lock);
 682 }
 683 EXPORT_SYMBOL_GPL(vhost_clear_msg);
 684
 685 void vhost_dev_cleanup(struct vhost_dev *dev)
 686 {
 687         int i;
 688
 689         for (i = 0; i < dev->nvqs; ++i) {
 690                 if (dev->vqs[i]->error_ctx)
 691                         eventfd_ctx_put(dev->vqs[i]->error_ctx);
 692                 if (dev->vqs[i]->kick)
 693                         fput(dev->vqs[i]->kick);
 694                 if (dev->vqs[i]->call_ctx.ctx)
 695                         eventfd_ctx_put(dev->vqs[i]->call_ctx.ctx);
 696                 vhost_vq_reset(dev, dev->vqs[i]);
 697         }
 698         vhost_dev_free_iovecs(dev);
 699         if (dev->log_ctx)
 700                 eventfd_ctx_put(dev->log_ctx);
 701         dev->log_ctx = NULL;
 702         /* No one will access memory at this point */
 703         vhost_iotlb_free(dev->umem);
 704         dev->umem = NULL;
 705         vhost_iotlb_free(dev->iotlb);
 706         dev->iotlb = NULL;
 707         vhost_clear_msg(dev);
 708         wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
 709         vhost_worker_free(dev);
 710         vhost_detach_mm(dev);
 711 }
 712 EXPORT_SYMBOL_GPL(vhost_dev_cleanup);
 713
 714 static bool log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
 715 {
 716         u64 a = addr / VHOST_PAGE_SIZE / 8;
 717
 718         /* Make sure 64 bit math will not overflow. */
 719         if (a > ULONG_MAX - (unsigned long)log_base ||
 720             a + (unsigned long)log_base > ULONG_MAX)
 721                 return false;
 722
 723         return access_ok(log_base + a,
 724                          (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8);
 725 }
 726
 727 /* Make sure 64 bit math will not overflow. */
 728 static bool vhost_overflow(u64 uaddr, u64 size)
 729 {
 730         if (uaddr > ULONG_MAX || size > ULONG_MAX)
 731                 return true;
 732
 733         if (!size)
 734                 return false;
 735
 736         return uaddr > ULONG_MAX - size + 1;
 737 }
 738
 739 /* Caller should have vq mutex and device mutex. */
 740 static bool vq_memory_access_ok(void __user *log_base, struct vhost_iotlb *umem,
 741                                 int log_all)
 742 {
 743         struct vhost_iotlb_map *map;
 744
 745         if (!umem)
 746                 return false;
 747
 748         list_for_each_entry(map, &umem->list, link) {
 749                 unsigned long a = map->addr;
 750
 751                 if (vhost_overflow(map->addr, map->size))
 752                         return false;
 753
 754
 755                 if (!access_ok((void __user *)a, map->size))
 756                         return false;
 757                 else if (log_all && !log_access_ok(log_base,
 758                                                    map->start,
 759                                                    map->size))
 760                         return false;
 761         }
 762         return true;
 763 }
 764
 765 static inline void __user *vhost_vq_meta_fetch(struct vhost_virtqueue *vq,
 766                                                u64 addr, unsigned int size,
 767                                                int type)
 768 {
 769         const struct vhost_iotlb_map *map = vq->meta_iotlb[type];
 770
 771         if (!map)
 772                 return NULL;
 773
 774         return (void __user *)(uintptr_t)(map->addr + addr - map->start);
 775 }
 776
 777 /* Can we switch to this memory table? */
 778 /* Caller should have device mutex but not vq mutex */
 779 static bool memory_access_ok(struct vhost_dev *d, struct vhost_iotlb *umem,
 780                              int log_all)
 781 {
 782         int i;
 783
 784         for (i = 0; i < d->nvqs; ++i) {
 785                 bool ok;
 786                 bool log;
 787
 788                 mutex_lock(&d->vqs[i]->mutex);
 789                 log = log_all || vhost_has_feature(d->vqs[i], VHOST_F_LOG_ALL);
 790                 /* If ring is inactive, will check when it's enabled. */
 791                 if (d->vqs[i]->private_data)
 792                         ok = vq_memory_access_ok(d->vqs[i]->log_base,
 793                                                  umem, log);
 794                 else
 795                         ok = true;
 796                 mutex_unlock(&d->vqs[i]->mutex);
 797                 if (!ok)
 798                         return false;
 799         }
 800         return true;
 801 }
 802
 803 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
 804                           struct iovec iov[], int iov_size, int access);
 805
 806 static int vhost_copy_to_user(struct vhost_virtqueue *vq, void __user *to,
 807                               const void *from, unsigned size)
 808 {
 809         int ret;
 810
 811         if (!vq->iotlb)
 812                 return __copy_to_user(to, from, size);
 813         else {
 814                 /* This function should be called after iotlb
 815                  * prefetch, which means we're sure that all vq
 816                  * could be access through iotlb. So -EAGAIN should
 817                  * not happen in this case.
 818                  */
 819                 struct iov_iter t;
 820                 void __user *uaddr = vhost_vq_meta_fetch(vq,
 821                                      (u64)(uintptr_t)to, size,
 822                                      VHOST_ADDR_USED);
 823
 824                 if (uaddr)
 825                         return __copy_to_user(uaddr, from, size);
 826
 827                 ret = translate_desc(vq, (u64)(uintptr_t)to, size, vq->iotlb_iov,
 828                                      ARRAY_SIZE(vq->iotlb_iov),
 829                                      VHOST_ACCESS_WO);
 830                 if (ret < 0)
 831                         goto out;
 832                 iov_iter_init(&t, ITER_DEST, vq->iotlb_iov, ret, size);
 833                 ret = copy_to_iter(from, size, &t);
 834                 if (ret == size)
 835                         ret = 0;
 836         }
 837 out:
 838         return ret;
 839 }
 840
 841 static int vhost_copy_from_user(struct vhost_virtqueue *vq, void *to,
 842                                 void __user *from, unsigned size)
 843 {
 844         int ret;
 845
 846         if (!vq->iotlb)
 847                 return __copy_from_user(to, from, size);
 848         else {
 849                 /* This function should be called after iotlb
 850                  * prefetch, which means we're sure that vq
 851                  * could be access through iotlb. So -EAGAIN should
 852                  * not happen in this case.
 853                  */
 854                 void __user *uaddr = vhost_vq_meta_fetch(vq,
 855                                      (u64)(uintptr_t)from, size,
 856                                      VHOST_ADDR_DESC);
 857                 struct iov_iter f;
 858
 859                 if (uaddr)
 860                         return __copy_from_user(to, uaddr, size);
 861
 862                 ret = translate_desc(vq, (u64)(uintptr_t)from, size, vq->iotlb_iov,
 863                                      ARRAY_SIZE(vq->iotlb_iov),
 864                                      VHOST_ACCESS_RO);
 865                 if (ret < 0) {
 866                         vq_err(vq, "IOTLB translation failure: uaddr "
 867                                "%p size 0x%llx\n", from,
 868                                (unsigned long long) size);
 869                         goto out;
 870                 }
 871                 iov_iter_init(&f, ITER_SOURCE, vq->iotlb_iov, ret, size);
 872                 ret = copy_from_iter(to, size, &f);
 873                 if (ret == size)
 874                         ret = 0;
 875         }
 876
 877 out:
 878         return ret;
 879 }
 880
 881 static void __user *__vhost_get_user_slow(struct vhost_virtqueue *vq,
 882                                           void __user *addr, unsigned int size,
 883                                           int type)
 884 {
 885         int ret;
 886
 887         ret = translate_desc(vq, (u64)(uintptr_t)addr, size, vq->iotlb_iov,
 888                              ARRAY_SIZE(vq->iotlb_iov),
 889                              VHOST_ACCESS_RO);
 890         if (ret < 0) {
 891                 vq_err(vq, "IOTLB translation failure: uaddr "
 892                         "%p size 0x%llx\n", addr,
 893                         (unsigned long long) size);
 894                 return NULL;
 895         }
 896
 897         if (ret != 1 || vq->iotlb_iov[0].iov_len != size) {
 898                 vq_err(vq, "Non atomic userspace memory access: uaddr "
 899                         "%p size 0x%llx\n", addr,
 900                         (unsigned long long) size);
 901                 return NULL;
 902         }
 903
 904         return vq->iotlb_iov[0].iov_base;
 905 }
 906
 907 /* This function should be called after iotlb
 908  * prefetch, which means we're sure that vq
 909  * could be access through iotlb. So -EAGAIN should
 910  * not happen in this case.
 911  */
 912 static inline void __user *__vhost_get_user(struct vhost_virtqueue *vq,
 913                                             void __user *addr, unsigned int size,
 914                                             int type)
 915 {
 916         void __user *uaddr = vhost_vq_meta_fetch(vq,
 917                              (u64)(uintptr_t)addr, size, type);
 918         if (uaddr)
 919                 return uaddr;
 920
 921         return __vhost_get_user_slow(vq, addr, size, type);
 922 }
 923
 924 #define vhost_put_user(vq, x, ptr)              \
 925 ({ \
 926         int ret; \
 927         if (!vq->iotlb) { \
 928                 ret = __put_user(x, ptr); \
 929         } else { \
 930                 __typeof__(ptr) to = \
 931                         (__typeof__(ptr)) __vhost_get_user(vq, ptr,     \
 932                                           sizeof(*ptr), VHOST_ADDR_USED); \
 933                 if (to != NULL) \
 934                         ret = __put_user(x, to); \
 935                 else \
 936                         ret = -EFAULT;  \
 937         } \
 938         ret; \
 939 })
 940
 941 static inline int vhost_put_avail_event(struct vhost_virtqueue *vq)
 942 {
 943         return vhost_put_user(vq, cpu_to_vhost16(vq, vq->avail_idx),
 944                               vhost_avail_event(vq));
 945 }
 946
 947 static inline int vhost_put_used(struct vhost_virtqueue *vq,
 948                                  struct vring_used_elem *head, int idx,
 949                                  int count)
 950 {
 951         return vhost_copy_to_user(vq, vq->used->ring + idx, head,
 952                                   count * sizeof(*head));
 953 }
 954
 955 static inline int vhost_put_used_flags(struct vhost_virtqueue *vq)
 956
 957 {
 958         return vhost_put_user(vq, cpu_to_vhost16(vq, vq->used_flags),
 959                               &vq->used->flags);
 960 }
 961
 962 static inline int vhost_put_used_idx(struct vhost_virtqueue *vq)
 963
 964 {
 965         return vhost_put_user(vq, cpu_to_vhost16(vq, vq->last_used_idx),
 966                               &vq->used->idx);
 967 }
 968
 969 #define vhost_get_user(vq, x, ptr, type)                \
 970 ({ \
 971         int ret; \
 972         if (!vq->iotlb) { \
 973                 ret = __get_user(x, ptr); \
 974         } else { \
 975                 __typeof__(ptr) from = \
 976                         (__typeof__(ptr)) __vhost_get_user(vq, ptr, \
 977                                                            sizeof(*ptr), \
 978                                                            type); \
 979                 if (from != NULL) \
 980                         ret = __get_user(x, from); \
 981                 else \
 982                         ret = -EFAULT; \
 983         } \
 984         ret; \
 985 })
 986
 987 #define vhost_get_avail(vq, x, ptr) \
 988         vhost_get_user(vq, x, ptr, VHOST_ADDR_AVAIL)
 989
 990 #define vhost_get_used(vq, x, ptr) \
 991         vhost_get_user(vq, x, ptr, VHOST_ADDR_USED)
 992
 993 static void vhost_dev_lock_vqs(struct vhost_dev *d)
 994 {
 995         int i = 0;
 996         for (i = 0; i < d->nvqs; ++i)
 997                 mutex_lock_nested(&d->vqs[i]->mutex, i);
 998 }
 999
1000 static void vhost_dev_unlock_vqs(struct vhost_dev *d)
1001 {
1002         int i = 0;
1003         for (i = 0; i < d->nvqs; ++i)
1004                 mutex_unlock(&d->vqs[i]->mutex);
1005 }
1006
1007 static inline int vhost_get_avail_idx(struct vhost_virtqueue *vq,
1008                                       __virtio16 *idx)
1009 {
1010         return vhost_get_avail(vq, *idx, &vq->avail->idx);
1011 }
1012
1013 static inline int vhost_get_avail_head(struct vhost_virtqueue *vq,
1014                                        __virtio16 *head, int idx)
1015 {
1016         return vhost_get_avail(vq, *head,
1017                                &vq->avail->ring[idx & (vq->num - 1)]);
1018 }
1019
1020 static inline int vhost_get_avail_flags(struct vhost_virtqueue *vq,
1021                                         __virtio16 *flags)
1022 {
1023         return vhost_get_avail(vq, *flags, &vq->avail->flags);
1024 }
1025
1026 static inline int vhost_get_used_event(struct vhost_virtqueue *vq,
1027                                        __virtio16 *event)
1028 {
1029         return vhost_get_avail(vq, *event, vhost_used_event(vq));
1030 }
1031
1032 static inline int vhost_get_used_idx(struct vhost_virtqueue *vq,
1033                                      __virtio16 *idx)
1034 {
1035         return vhost_get_used(vq, *idx, &vq->used->idx);
1036 }
1037
1038 static inline int vhost_get_desc(struct vhost_virtqueue *vq,
1039                                  struct vring_desc *desc, int idx)
1040 {
1041         return vhost_copy_from_user(vq, desc, vq->desc + idx, sizeof(*desc));
1042 }
1043
1044 static void vhost_iotlb_notify_vq(struct vhost_dev *d,
1045                                   struct vhost_iotlb_msg *msg)
1046 {
1047         struct vhost_msg_node *node, *n;
1048
1049         spin_lock(&d->iotlb_lock);
1050
1051         list_for_each_entry_safe(node, n, &d->pending_list, node) {
1052                 struct vhost_iotlb_msg *vq_msg = &node->msg.iotlb;
1053                 if (msg->iova <= vq_msg->iova &&
1054                     msg->iova + msg->size - 1 >= vq_msg->iova &&
1055                     vq_msg->type == VHOST_IOTLB_MISS) {
1056                         vhost_poll_queue(&node->vq->poll);
1057                         list_del(&node->node);
1058                         kfree(node);
1059                 }
1060         }
1061
1062         spin_unlock(&d->iotlb_lock);
1063 }
1064
1065 static bool umem_access_ok(u64 uaddr, u64 size, int access)
1066 {
1067         unsigned long a = uaddr;
1068
1069         /* Make sure 64 bit math will not overflow. */
1070         if (vhost_overflow(uaddr, size))
1071                 return false;
1072
1073         if ((access & VHOST_ACCESS_RO) &&
1074             !access_ok((void __user *)a, size))
1075                 return false;
1076         if ((access & VHOST_ACCESS_WO) &&
1077             !access_ok((void __user *)a, size))
1078                 return false;
1079         return true;
1080 }
1081
1082 static int vhost_process_iotlb_msg(struct vhost_dev *dev, u32 asid,
1083                                    struct vhost_iotlb_msg *msg)
1084 {
1085         int ret = 0;
1086
1087         if (asid != 0)
1088                 return -EINVAL;
1089
1090         mutex_lock(&dev->mutex);
1091         vhost_dev_lock_vqs(dev);
1092         switch (msg->type) {
1093         case VHOST_IOTLB_UPDATE:
1094                 if (!dev->iotlb) {
1095                         ret = -EFAULT;
1096                         break;
1097                 }
1098                 if (!umem_access_ok(msg->uaddr, msg->size, msg->perm)) {
1099                         ret = -EFAULT;
1100                         break;
1101                 }
1102                 vhost_vq_meta_reset(dev);
1103                 if (vhost_iotlb_add_range(dev->iotlb, msg->iova,
1104                                           msg->iova + msg->size - 1,
1105                                           msg->uaddr, msg->perm)) {
1106                         ret = -ENOMEM;
1107                         break;
1108                 }
1109                 vhost_iotlb_notify_vq(dev, msg);
1110                 break;
1111         case VHOST_IOTLB_INVALIDATE:
1112                 if (!dev->iotlb) {
1113                         ret = -EFAULT;
1114                         break;
1115                 }
1116                 vhost_vq_meta_reset(dev);
1117                 vhost_iotlb_del_range(dev->iotlb, msg->iova,
1118                                       msg->iova + msg->size - 1);
1119                 break;
1120         default:
1121                 ret = -EINVAL;
1122                 break;
1123         }
1124
1125         vhost_dev_unlock_vqs(dev);
1126         mutex_unlock(&dev->mutex);
1127
1128         return ret;
1129 }
1130 ssize_t vhost_chr_write_iter(struct vhost_dev *dev,
1131                              struct iov_iter *from)
1132 {
1133         struct vhost_iotlb_msg msg;
1134         size_t offset;
1135         int type, ret;
1136         u32 asid = 0;
1137
1138         ret = copy_from_iter(&type, sizeof(type), from);
1139         if (ret != sizeof(type)) {
1140                 ret = -EINVAL;
1141                 goto done;
1142         }
1143
1144         switch (type) {
1145         case VHOST_IOTLB_MSG:
1146                 /* There maybe a hole after type for V1 message type,
1147                  * so skip it here.
1148                  */
1149                 offset = offsetof(struct vhost_msg, iotlb) - sizeof(int);
1150                 break;
1151         case VHOST_IOTLB_MSG_V2:
1152                 if (vhost_backend_has_feature(dev->vqs[0],
1153                                               VHOST_BACKEND_F_IOTLB_ASID)) {
1154                         ret = copy_from_iter(&asid, sizeof(asid), from);
1155                         if (ret != sizeof(asid)) {
1156                                 ret = -EINVAL;
1157                                 goto done;
1158                         }
1159                         offset = 0;
1160                 } else
1161                         offset = sizeof(__u32);
1162                 break;
1163         default:
1164                 ret = -EINVAL;
1165                 goto done;
1166         }
1167
1168         iov_iter_advance(from, offset);
1169         ret = copy_from_iter(&msg, sizeof(msg), from);
1170         if (ret != sizeof(msg)) {
1171                 ret = -EINVAL;
1172                 goto done;
1173         }
1174
1175         if ((msg.type == VHOST_IOTLB_UPDATE ||
1176              msg.type == VHOST_IOTLB_INVALIDATE) &&
1177              msg.size == 0) {
1178                 ret = -EINVAL;
1179                 goto done;
1180         }
1181
1182         if (dev->msg_handler)
1183                 ret = dev->msg_handler(dev, asid, &msg);
1184         else
1185                 ret = vhost_process_iotlb_msg(dev, asid, &msg);
1186         if (ret) {
1187                 ret = -EFAULT;
1188                 goto done;
1189         }
1190
1191         ret = (type == VHOST_IOTLB_MSG) ? sizeof(struct vhost_msg) :
1192               sizeof(struct vhost_msg_v2);
1193 done:
1194         return ret;
1195 }
1196 EXPORT_SYMBOL(vhost_chr_write_iter);
1197
1198 __poll_t vhost_chr_poll(struct file *file, struct vhost_dev *dev,
1199                             poll_table *wait)
1200 {
1201         __poll_t mask = 0;
1202
1203         poll_wait(file, &dev->wait, wait);
1204
1205         if (!list_empty(&dev->read_list))
1206                 mask |= EPOLLIN | EPOLLRDNORM;
1207
1208         return mask;
1209 }
1210 EXPORT_SYMBOL(vhost_chr_poll);
1211
1212 ssize_t vhost_chr_read_iter(struct vhost_dev *dev, struct iov_iter *to,
1213                             int noblock)
1214 {
1215         DEFINE_WAIT(wait);
1216         struct vhost_msg_node *node;
1217         ssize_t ret = 0;
1218         unsigned size = sizeof(struct vhost_msg);
1219
1220         if (iov_iter_count(to) < size)
1221                 return 0;
1222
1223         while (1) {
1224                 if (!noblock)
1225                         prepare_to_wait(&dev->wait, &wait,
1226                                         TASK_INTERRUPTIBLE);
1227
1228                 node = vhost_dequeue_msg(dev, &dev->read_list);
1229                 if (node)
1230                         break;
1231                 if (noblock) {
1232                         ret = -EAGAIN;
1233                         break;
1234                 }
1235                 if (signal_pending(current)) {
1236                         ret = -ERESTARTSYS;
1237                         break;
1238                 }
1239                 if (!dev->iotlb) {
1240                         ret = -EBADFD;
1241                         break;
1242                 }
1243
1244                 schedule();
1245         }
1246
1247         if (!noblock)
1248                 finish_wait(&dev->wait, &wait);
1249
1250         if (node) {
1251                 struct vhost_iotlb_msg *msg;
1252                 void *start = &node->msg;
1253
1254                 switch (node->msg.type) {
1255                 case VHOST_IOTLB_MSG:
1256                         size = sizeof(node->msg);
1257                         msg = &node->msg.iotlb;
1258                         break;
1259                 case VHOST_IOTLB_MSG_V2:
1260                         size = sizeof(node->msg_v2);
1261                         msg = &node->msg_v2.iotlb;
1262                         break;
1263                 default:
1264                         BUG();
1265                         break;
1266                 }
1267
1268                 ret = copy_to_iter(start, size, to);
1269                 if (ret != size || msg->type != VHOST_IOTLB_MISS) {
1270                         kfree(node);
1271                         return ret;
1272                 }
1273                 vhost_enqueue_msg(dev, &dev->pending_list, node);
1274         }
1275
1276         return ret;
1277 }
1278 EXPORT_SYMBOL_GPL(vhost_chr_read_iter);
1279
1280 static int vhost_iotlb_miss(struct vhost_virtqueue *vq, u64 iova, int access)
1281 {
1282         struct vhost_dev *dev = vq->dev;
1283         struct vhost_msg_node *node;
1284         struct vhost_iotlb_msg *msg;
1285         bool v2 = vhost_backend_has_feature(vq, VHOST_BACKEND_F_IOTLB_MSG_V2);
1286
1287         node = vhost_new_msg(vq, v2 ? VHOST_IOTLB_MSG_V2 : VHOST_IOTLB_MSG);
1288         if (!node)
1289                 return -ENOMEM;
1290
1291         if (v2) {
1292                 node->msg_v2.type = VHOST_IOTLB_MSG_V2;
1293                 msg = &node->msg_v2.iotlb;
1294         } else {
1295                 msg = &node->msg.iotlb;
1296         }
1297
1298         msg->type = VHOST_IOTLB_MISS;
1299         msg->iova = iova;
1300         msg->perm = access;
1301
1302         vhost_enqueue_msg(dev, &dev->read_list, node);
1303
1304         return 0;
1305 }
1306
1307 static bool vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
1308                          vring_desc_t __user *desc,
1309                          vring_avail_t __user *avail,
1310                          vring_used_t __user *used)
1311
1312 {
1313         /* If an IOTLB device is present, the vring addresses are
1314          * GIOVAs. Access validation occurs at prefetch time. */
1315         if (vq->iotlb)
1316                 return true;
1317
1318         return access_ok(desc, vhost_get_desc_size(vq, num)) &&
1319                access_ok(avail, vhost_get_avail_size(vq, num)) &&
1320                access_ok(used, vhost_get_used_size(vq, num));
1321 }
1322
1323 static void vhost_vq_meta_update(struct vhost_virtqueue *vq,
1324                                  const struct vhost_iotlb_map *map,
1325                                  int type)
1326 {
1327         int access = (type == VHOST_ADDR_USED) ?
1328                      VHOST_ACCESS_WO : VHOST_ACCESS_RO;
1329
1330         if (likely(map->perm & access))
1331                 vq->meta_iotlb[type] = map;
1332 }
1333
1334 static bool iotlb_access_ok(struct vhost_virtqueue *vq,
1335                             int access, u64 addr, u64 len, int type)
1336 {
1337         const struct vhost_iotlb_map *map;
1338         struct vhost_iotlb *umem = vq->iotlb;
1339         u64 s = 0, size, orig_addr = addr, last = addr + len - 1;
1340
1341         if (vhost_vq_meta_fetch(vq, addr, len, type))
1342                 return true;
1343
1344         while (len > s) {
1345                 map = vhost_iotlb_itree_first(umem, addr, last);
1346                 if (map == NULL || map->start > addr) {
1347                         vhost_iotlb_miss(vq, addr, access);
1348                         return false;
1349                 } else if (!(map->perm & access)) {
1350                         /* Report the possible access violation by
1351                          * request another translation from userspace.
1352                          */
1353                         return false;
1354                 }
1355
1356                 size = map->size - addr + map->start;
1357
1358                 if (orig_addr == addr && size >= len)
1359                         vhost_vq_meta_update(vq, map, type);
1360
1361                 s += size;
1362                 addr += size;
1363         }
1364
1365         return true;
1366 }
1367
1368 int vq_meta_prefetch(struct vhost_virtqueue *vq)
1369 {
1370         unsigned int num = vq->num;
1371
1372         if (!vq->iotlb)
1373                 return 1;
1374
1375         return iotlb_access_ok(vq, VHOST_MAP_RO, (u64)(uintptr_t)vq->desc,
1376                                vhost_get_desc_size(vq, num), VHOST_ADDR_DESC) &&
1377                iotlb_access_ok(vq, VHOST_MAP_RO, (u64)(uintptr_t)vq->avail,
1378                                vhost_get_avail_size(vq, num),
1379                                VHOST_ADDR_AVAIL) &&
1380                iotlb_access_ok(vq, VHOST_MAP_WO, (u64)(uintptr_t)vq->used,
1381                                vhost_get_used_size(vq, num), VHOST_ADDR_USED);
1382 }
1383 EXPORT_SYMBOL_GPL(vq_meta_prefetch);
1384
1385 /* Can we log writes? */
1386 /* Caller should have device mutex but not vq mutex */
1387 bool vhost_log_access_ok(struct vhost_dev *dev)
1388 {
1389         return memory_access_ok(dev, dev->umem, 1);
1390 }
1391 EXPORT_SYMBOL_GPL(vhost_log_access_ok);
1392
1393 static bool vq_log_used_access_ok(struct vhost_virtqueue *vq,
1394                                   void __user *log_base,
1395                                   bool log_used,
1396                                   u64 log_addr)
1397 {
1398         /* If an IOTLB device is present, log_addr is a GIOVA that
1399          * will never be logged by log_used(). */
1400         if (vq->iotlb)
1401                 return true;
1402
1403         return !log_used || log_access_ok(log_base, log_addr,
1404                                           vhost_get_used_size(vq, vq->num));
1405 }
1406
1407 /* Verify access for write logging. */
1408 /* Caller should have vq mutex and device mutex */
1409 static bool vq_log_access_ok(struct vhost_virtqueue *vq,
1410                              void __user *log_base)
1411 {
1412         return vq_memory_access_ok(log_base, vq->umem,
1413                                    vhost_has_feature(vq, VHOST_F_LOG_ALL)) &&
1414                 vq_log_used_access_ok(vq, log_base, vq->log_used, vq->log_addr);
1415 }
1416
1417 /* Can we start vq? */
1418 /* Caller should have vq mutex and device mutex */
1419 bool vhost_vq_access_ok(struct vhost_virtqueue *vq)
1420 {
1421         if (!vq_log_access_ok(vq, vq->log_base))
1422                 return false;
1423
1424         return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used);
1425 }
1426 EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
1427
1428 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
1429 {
1430         struct vhost_memory mem, *newmem;
1431         struct vhost_memory_region *region;
1432         struct vhost_iotlb *newumem, *oldumem;
1433         unsigned long size = offsetof(struct vhost_memory, regions);
1434         int i;
1435
1436         if (copy_from_user(&mem, m, size))
1437                 return -EFAULT;
1438         if (mem.padding)
1439                 return -EOPNOTSUPP;
1440         if (mem.nregions > max_mem_regions)
1441                 return -E2BIG;
1442         newmem = kvzalloc(struct_size(newmem, regions, mem.nregions),
1443                         GFP_KERNEL);
1444         if (!newmem)
1445                 return -ENOMEM;
1446
1447         memcpy(newmem, &mem, size);
1448         if (copy_from_user(newmem->regions, m->regions,
1449                            flex_array_size(newmem, regions, mem.nregions))) {
1450                 kvfree(newmem);
1451                 return -EFAULT;
1452         }
1453
1454         newumem = iotlb_alloc();
1455         if (!newumem) {
1456                 kvfree(newmem);
1457                 return -ENOMEM;
1458         }
1459
1460         for (region = newmem->regions;
1461              region < newmem->regions + mem.nregions;
1462              region++) {
1463                 if (vhost_iotlb_add_range(newumem,
1464                                           region->guest_phys_addr,
1465                                           region->guest_phys_addr +
1466                                           region->memory_size - 1,
1467                                           region->userspace_addr,
1468                                           VHOST_MAP_RW))
1469                         goto err;
1470         }
1471
1472         if (!memory_access_ok(d, newumem, 0))
1473                 goto err;
1474
1475         oldumem = d->umem;
1476         d->umem = newumem;
1477
1478         /* All memory accesses are done under some VQ mutex. */
1479         for (i = 0; i < d->nvqs; ++i) {
1480                 mutex_lock(&d->vqs[i]->mutex);
1481                 d->vqs[i]->umem = newumem;
1482                 mutex_unlock(&d->vqs[i]->mutex);
1483         }
1484
1485         kvfree(newmem);
1486         vhost_iotlb_free(oldumem);
1487         return 0;
1488
1489 err:
1490         vhost_iotlb_free(newumem);
1491         kvfree(newmem);
1492         return -EFAULT;
1493 }
1494
1495 static long vhost_vring_set_num(struct vhost_dev *d,
1496                                 struct vhost_virtqueue *vq,
1497                                 void __user *argp)
1498 {
1499         struct vhost_vring_state s;
1500
1501         /* Resizing ring with an active backend?
1502          * You don't want to do that. */
1503         if (vq->private_data)
1504                 return -EBUSY;
1505
1506         if (copy_from_user(&s, argp, sizeof s))
1507                 return -EFAULT;
1508
1509         if (!s.num || s.num > 0xffff || (s.num & (s.num - 1)))
1510                 return -EINVAL;
1511         vq->num = s.num;
1512
1513         return 0;
1514 }
1515
1516 static long vhost_vring_set_addr(struct vhost_dev *d,
1517                                  struct vhost_virtqueue *vq,
1518                                  void __user *argp)
1519 {
1520         struct vhost_vring_addr a;
1521
1522         if (copy_from_user(&a, argp, sizeof a))
1523                 return -EFAULT;
1524         if (a.flags & ~(0x1 << VHOST_VRING_F_LOG))
1525                 return -EOPNOTSUPP;
1526
1527         /* For 32bit, verify that the top 32bits of the user
1528            data are set to zero. */
1529         if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr ||
1530             (u64)(unsigned long)a.used_user_addr != a.used_user_addr ||
1531             (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr)
1532                 return -EFAULT;
1533
1534         /* Make sure it's safe to cast pointers to vring types. */
1535         BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE);
1536         BUILD_BUG_ON(__alignof__ *vq->used > VRING_USED_ALIGN_SIZE);
1537         if ((a.avail_user_addr & (VRING_AVAIL_ALIGN_SIZE - 1)) ||
1538             (a.used_user_addr & (VRING_USED_ALIGN_SIZE - 1)) ||
1539             (a.log_guest_addr & (VRING_USED_ALIGN_SIZE - 1)))
1540                 return -EINVAL;
1541
1542         /* We only verify access here if backend is configured.
1543          * If it is not, we don't as size might not have been setup.
1544          * We will verify when backend is configured. */
1545         if (vq->private_data) {
1546                 if (!vq_access_ok(vq, vq->num,
1547                         (void __user *)(unsigned long)a.desc_user_addr,
1548                         (void __user *)(unsigned long)a.avail_user_addr,
1549                         (void __user *)(unsigned long)a.used_user_addr))
1550                         return -EINVAL;
1551
1552                 /* Also validate log access for used ring if enabled. */
1553                 if (!vq_log_used_access_ok(vq, vq->log_base,
1554                                 a.flags & (0x1 << VHOST_VRING_F_LOG),
1555                                 a.log_guest_addr))
1556                         return -EINVAL;
1557         }
1558
1559         vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
1560         vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
1561         vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
1562         vq->log_addr = a.log_guest_addr;
1563         vq->used = (void __user *)(unsigned long)a.used_user_addr;
1564
1565         return 0;
1566 }
1567
1568 static long vhost_vring_set_num_addr(struct vhost_dev *d,
1569                                      struct vhost_virtqueue *vq,
1570                                      unsigned int ioctl,
1571                                      void __user *argp)
1572 {
1573         long r;
1574
1575         mutex_lock(&vq->mutex);
1576
1577         switch (ioctl) {
1578         case VHOST_SET_VRING_NUM:
1579                 r = vhost_vring_set_num(d, vq, argp);
1580                 break;
1581         case VHOST_SET_VRING_ADDR:
1582                 r = vhost_vring_set_addr(d, vq, argp);
1583                 break;
1584         default:
1585                 BUG();
1586         }
1587
1588         mutex_unlock(&vq->mutex);
1589
1590         return r;
1591 }
1592 long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
1593 {
1594         struct file *eventfp, *filep = NULL;
1595         bool pollstart = false, pollstop = false;
1596         struct eventfd_ctx *ctx = NULL;
1597         u32 __user *idxp = argp;
1598         struct vhost_virtqueue *vq;
1599         struct vhost_vring_state s;
1600         struct vhost_vring_file f;
1601         u32 idx;
1602         long r;
1603
1604         r = get_user(idx, idxp);
1605         if (r < 0)
1606                 return r;
1607         if (idx >= d->nvqs)
1608                 return -ENOBUFS;
1609
1610         idx = array_index_nospec(idx, d->nvqs);
1611         vq = d->vqs[idx];
1612
1613         if (ioctl == VHOST_SET_VRING_NUM ||
1614             ioctl == VHOST_SET_VRING_ADDR) {
1615                 return vhost_vring_set_num_addr(d, vq, ioctl, argp);
1616         }
1617
1618         mutex_lock(&vq->mutex);
1619
1620         switch (ioctl) {
1621         case VHOST_SET_VRING_BASE:
1622                 /* Moving base with an active backend?
1623                  * You don't want to do that. */
1624                 if (vq->private_data) {
1625                         r = -EBUSY;
1626                         break;
1627                 }
1628                 if (copy_from_user(&s, argp, sizeof s)) {
1629                         r = -EFAULT;
1630                         break;
1631                 }
1632                 if (s.num > 0xffff) {
1633                         r = -EINVAL;
1634                         break;
1635                 }
1636                 vq->last_avail_idx = s.num;
1637                 /* Forget the cached index value. */
1638                 vq->avail_idx = vq->last_avail_idx;
1639                 break;
1640         case VHOST_GET_VRING_BASE:
1641                 s.index = idx;
1642                 s.num = vq->last_avail_idx;
1643                 if (copy_to_user(argp, &s, sizeof s))
1644                         r = -EFAULT;
1645                 break;
1646         case VHOST_SET_VRING_KICK:
1647                 if (copy_from_user(&f, argp, sizeof f)) {
1648                         r = -EFAULT;
1649                         break;
1650                 }
1651                 eventfp = f.fd == VHOST_FILE_UNBIND ? NULL : eventfd_fget(f.fd);
1652                 if (IS_ERR(eventfp)) {
1653                         r = PTR_ERR(eventfp);
1654                         break;
1655                 }
1656                 if (eventfp != vq->kick) {
1657                         pollstop = (filep = vq->kick) != NULL;
1658                         pollstart = (vq->kick = eventfp) != NULL;
1659                 } else
1660                         filep = eventfp;
1661                 break;
1662         case VHOST_SET_VRING_CALL:
1663                 if (copy_from_user(&f, argp, sizeof f)) {
1664                         r = -EFAULT;
1665                         break;
1666                 }
1667                 ctx = f.fd == VHOST_FILE_UNBIND ? NULL : eventfd_ctx_fdget(f.fd);
1668                 if (IS_ERR(ctx)) {
1669                         r = PTR_ERR(ctx);
1670                         break;
1671                 }
1672
1673                 swap(ctx, vq->call_ctx.ctx);
1674                 break;
1675         case VHOST_SET_VRING_ERR:
1676                 if (copy_from_user(&f, argp, sizeof f)) {
1677                         r = -EFAULT;
1678                         break;
1679                 }
1680                 ctx = f.fd == VHOST_FILE_UNBIND ? NULL : eventfd_ctx_fdget(f.fd);
1681                 if (IS_ERR(ctx)) {
1682                         r = PTR_ERR(ctx);
1683                         break;
1684                 }
1685                 swap(ctx, vq->error_ctx);
1686                 break;
1687         case VHOST_SET_VRING_ENDIAN:
1688                 r = vhost_set_vring_endian(vq, argp);
1689                 break;
1690         case VHOST_GET_VRING_ENDIAN:
1691                 r = vhost_get_vring_endian(vq, idx, argp);
1692                 break;
1693         case VHOST_SET_VRING_BUSYLOOP_TIMEOUT:
1694                 if (copy_from_user(&s, argp, sizeof(s))) {
1695                         r = -EFAULT;
1696                         break;
1697                 }
1698                 vq->busyloop_timeout = s.num;
1699                 break;
1700         case VHOST_GET_VRING_BUSYLOOP_TIMEOUT:
1701                 s.index = idx;
1702                 s.num = vq->busyloop_timeout;
1703                 if (copy_to_user(argp, &s, sizeof(s)))
1704                         r = -EFAULT;
1705                 break;
1706         default:
1707                 r = -ENOIOCTLCMD;
1708         }
1709
1710         if (pollstop && vq->handle_kick)
1711                 vhost_poll_stop(&vq->poll);
1712
1713         if (!IS_ERR_OR_NULL(ctx))
1714                 eventfd_ctx_put(ctx);
1715         if (filep)
1716                 fput(filep);
1717
1718         if (pollstart && vq->handle_kick)
1719                 r = vhost_poll_start(&vq->poll, vq->kick);
1720
1721         mutex_unlock(&vq->mutex);
1722
1723         if (pollstop && vq->handle_kick)
1724                 vhost_dev_flush(vq->poll.dev);
1725         return r;
1726 }
1727 EXPORT_SYMBOL_GPL(vhost_vring_ioctl);
1728
1729 int vhost_init_device_iotlb(struct vhost_dev *d)
1730 {
1731         struct vhost_iotlb *niotlb, *oiotlb;
1732         int i;
1733
1734         niotlb = iotlb_alloc();
1735         if (!niotlb)
1736                 return -ENOMEM;
1737
1738         oiotlb = d->iotlb;
1739         d->iotlb = niotlb;
1740
1741         for (i = 0; i < d->nvqs; ++i) {
1742                 struct vhost_virtqueue *vq = d->vqs[i];
1743
1744                 mutex_lock(&vq->mutex);
1745                 vq->iotlb = niotlb;
1746                 __vhost_vq_meta_reset(vq);
1747                 mutex_unlock(&vq->mutex);
1748         }
1749
1750         vhost_iotlb_free(oiotlb);
1751
1752         return 0;
1753 }
1754 EXPORT_SYMBOL_GPL(vhost_init_device_iotlb);
1755
1756 /* Caller must have device mutex */
1757 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
1758 {
1759         struct eventfd_ctx *ctx;
1760         u64 p;
1761         long r;
1762         int i, fd;
1763
1764         /* If you are not the owner, you can become one */
1765         if (ioctl == VHOST_SET_OWNER) {
1766                 r = vhost_dev_set_owner(d);
1767                 goto done;
1768         }
1769
1770         /* You must be the owner to do anything else */
1771         r = vhost_dev_check_owner(d);
1772         if (r)
1773                 goto done;
1774
1775         switch (ioctl) {
1776         case VHOST_SET_MEM_TABLE:
1777                 r = vhost_set_memory(d, argp);
1778                 break;
1779         case VHOST_SET_LOG_BASE:
1780                 if (copy_from_user(&p, argp, sizeof p)) {
1781                         r = -EFAULT;
1782                         break;
1783                 }
1784                 if ((u64)(unsigned long)p != p) {
1785                         r = -EFAULT;
1786                         break;
1787                 }
1788                 for (i = 0; i < d->nvqs; ++i) {
1789                         struct vhost_virtqueue *vq;
1790                         void __user *base = (void __user *)(unsigned long)p;
1791                         vq = d->vqs[i];
1792                         mutex_lock(&vq->mutex);
1793                         /* If ring is inactive, will check when it's enabled. */
1794                         if (vq->private_data && !vq_log_access_ok(vq, base))
1795                                 r = -EFAULT;
1796                         else
1797                                 vq->log_base = base;
1798                         mutex_unlock(&vq->mutex);
1799                 }
1800                 break;
1801         case VHOST_SET_LOG_FD:
1802                 r = get_user(fd, (int __user *)argp);
1803                 if (r < 0)
1804                         break;
1805                 ctx = fd == VHOST_FILE_UNBIND ? NULL : eventfd_ctx_fdget(fd);
1806                 if (IS_ERR(ctx)) {
1807                         r = PTR_ERR(ctx);
1808                         break;
1809                 }
1810                 swap(ctx, d->log_ctx);
1811                 for (i = 0; i < d->nvqs; ++i) {
1812                         mutex_lock(&d->vqs[i]->mutex);
1813                         d->vqs[i]->log_ctx = d->log_ctx;
1814                         mutex_unlock(&d->vqs[i]->mutex);
1815                 }
1816                 if (ctx)
1817                         eventfd_ctx_put(ctx);
1818                 break;
1819         default:
1820                 r = -ENOIOCTLCMD;
1821                 break;
1822         }
1823 done:
1824         return r;
1825 }
1826 EXPORT_SYMBOL_GPL(vhost_dev_ioctl);
1827
1828 /* TODO: This is really inefficient.  We need something like get_user()
1829  * (instruction directly accesses the data, with an exception table entry
1830  * returning -EFAULT). See Documentation/arch/x86/exception-tables.rst.
1831  */
1832 static int set_bit_to_user(int nr, void __user *addr)
1833 {
1834         unsigned long log = (unsigned long)addr;
1835         struct page *page;
1836         void *base;
1837         int bit = nr + (log % PAGE_SIZE) * 8;
1838         int r;
1839
1840         r = pin_user_pages_fast(log, 1, FOLL_WRITE, &page);
1841         if (r < 0)
1842                 return r;
1843         BUG_ON(r != 1);
1844         base = kmap_atomic(page);
1845         set_bit(bit, base);
1846         kunmap_atomic(base);
1847         unpin_user_pages_dirty_lock(&page, 1, true);
1848         return 0;
1849 }
1850
1851 static int log_write(void __user *log_base,
1852                      u64 write_address, u64 write_length)
1853 {
1854         u64 write_page = write_address / VHOST_PAGE_SIZE;
1855         int r;
1856
1857         if (!write_length)
1858                 return 0;
1859         write_length += write_address % VHOST_PAGE_SIZE;
1860         for (;;) {
1861                 u64 base = (u64)(unsigned long)log_base;
1862                 u64 log = base + write_page / 8;
1863                 int bit = write_page % 8;
1864                 if ((u64)(unsigned long)log != log)
1865                         return -EFAULT;
1866                 r = set_bit_to_user(bit, (void __user *)(unsigned long)log);
1867                 if (r < 0)
1868                         return r;
1869                 if (write_length <= VHOST_PAGE_SIZE)
1870                         break;
1871                 write_length -= VHOST_PAGE_SIZE;
1872                 write_page += 1;
1873         }
1874         return r;
1875 }
1876
1877 static int log_write_hva(struct vhost_virtqueue *vq, u64 hva, u64 len)
1878 {
1879         struct vhost_iotlb *umem = vq->umem;
1880         struct vhost_iotlb_map *u;
1881         u64 start, end, l, min;
1882         int r;
1883         bool hit = false;
1884
1885         while (len) {
1886                 min = len;
1887                 /* More than one GPAs can be mapped into a single HVA. So
1888                  * iterate all possible umems here to be safe.
1889                  */
1890                 list_for_each_entry(u, &umem->list, link) {
1891                         if (u->addr > hva - 1 + len ||
1892                             u->addr - 1 + u->size < hva)
1893                                 continue;
1894                         start = max(u->addr, hva);
1895                         end = min(u->addr - 1 + u->size, hva - 1 + len);
1896                         l = end - start + 1;
1897                         r = log_write(vq->log_base,
1898                                       u->start + start - u->addr,
1899                                       l);
1900                         if (r < 0)
1901                                 return r;
1902                         hit = true;
1903                         min = min(l, min);
1904                 }
1905
1906                 if (!hit)
1907                         return -EFAULT;
1908
1909                 len -= min;
1910                 hva += min;
1911         }
1912
1913         return 0;
1914 }
1915
1916 static int log_used(struct vhost_virtqueue *vq, u64 used_offset, u64 len)
1917 {
1918         struct iovec *iov = vq->log_iov;
1919         int i, ret;
1920
1921         if (!vq->iotlb)
1922                 return log_write(vq->log_base, vq->log_addr + used_offset, len);
1923
1924         ret = translate_desc(vq, (uintptr_t)vq->used + used_offset,
1925                              len, iov, 64, VHOST_ACCESS_WO);
1926         if (ret < 0)
1927                 return ret;
1928
1929         for (i = 0; i < ret; i++) {
1930                 ret = log_write_hva(vq, (uintptr_t)iov[i].iov_base,
1931                                     iov[i].iov_len);
1932                 if (ret)
1933                         return ret;
1934         }
1935
1936         return 0;
1937 }
1938
1939 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
1940                     unsigned int log_num, u64 len, struct iovec *iov, int count)
1941 {
1942         int i, r;
1943
1944         /* Make sure data written is seen before log. */
1945         smp_wmb();
1946
1947         if (vq->iotlb) {
1948                 for (i = 0; i < count; i++) {
1949                         r = log_write_hva(vq, (uintptr_t)iov[i].iov_base,
1950                                           iov[i].iov_len);
1951                         if (r < 0)
1952                                 return r;
1953                 }
1954                 return 0;
1955         }
1956
1957         for (i = 0; i < log_num; ++i) {
1958                 u64 l = min(log[i].len, len);
1959                 r = log_write(vq->log_base, log[i].addr, l);
1960                 if (r < 0)
1961                         return r;
1962                 len -= l;
1963                 if (!len) {
1964                         if (vq->log_ctx)
1965                                 eventfd_signal(vq->log_ctx, 1);
1966                         return 0;
1967                 }
1968         }
1969         /* Length written exceeds what we have stored. This is a bug. */
1970         BUG();
1971         return 0;
1972 }
1973 EXPORT_SYMBOL_GPL(vhost_log_write);
1974
1975 static int vhost_update_used_flags(struct vhost_virtqueue *vq)
1976 {
1977         void __user *used;
1978         if (vhost_put_used_flags(vq))
1979                 return -EFAULT;
1980         if (unlikely(vq->log_used)) {
1981                 /* Make sure the flag is seen before log. */
1982                 smp_wmb();
1983                 /* Log used flag write. */
1984                 used = &vq->used->flags;
1985                 log_used(vq, (used - (void __user *)vq->used),
1986                          sizeof vq->used->flags);
1987                 if (vq->log_ctx)
1988                         eventfd_signal(vq->log_ctx, 1);
1989         }
1990         return 0;
1991 }
1992
1993 static int vhost_update_avail_event(struct vhost_virtqueue *vq)
1994 {
1995         if (vhost_put_avail_event(vq))
1996                 return -EFAULT;
1997         if (unlikely(vq->log_used)) {
1998                 void __user *used;
1999                 /* Make sure the event is seen before log. */
2000                 smp_wmb();
2001                 /* Log avail event write */
2002                 used = vhost_avail_event(vq);
2003                 log_used(vq, (used - (void __user *)vq->used),
2004                          sizeof *vhost_avail_event(vq));
2005                 if (vq->log_ctx)
2006                         eventfd_signal(vq->log_ctx, 1);
2007         }
2008         return 0;
2009 }
2010
2011 int vhost_vq_init_access(struct vhost_virtqueue *vq)
2012 {
2013         __virtio16 last_used_idx;
2014         int r;
2015         bool is_le = vq->is_le;
2016
2017         if (!vq->private_data)
2018                 return 0;
2019
2020         vhost_init_is_le(vq);
2021
2022         r = vhost_update_used_flags(vq);
2023         if (r)
2024                 goto err;
2025         vq->signalled_used_valid = false;
2026         if (!vq->iotlb &&
2027             !access_ok(&vq->used->idx, sizeof vq->used->idx)) {
2028                 r = -EFAULT;
2029                 goto err;
2030         }
2031         r = vhost_get_used_idx(vq, &last_used_idx);
2032         if (r) {
2033                 vq_err(vq, "Can't access used idx at %p\n",
2034                        &vq->used->idx);
2035                 goto err;
2036         }
2037         vq->last_used_idx = vhost16_to_cpu(vq, last_used_idx);
2038         return 0;
2039
2040 err:
2041         vq->is_le = is_le;
2042         return r;
2043 }
2044 EXPORT_SYMBOL_GPL(vhost_vq_init_access);
2045
2046 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
2047                           struct iovec iov[], int iov_size, int access)
2048 {
2049         const struct vhost_iotlb_map *map;
2050         struct vhost_dev *dev = vq->dev;
2051         struct vhost_iotlb *umem = dev->iotlb ? dev->iotlb : dev->umem;
2052         struct iovec *_iov;
2053         u64 s = 0, last = addr + len - 1;
2054         int ret = 0;
2055
2056         while ((u64)len > s) {
2057                 u64 size;
2058                 if (unlikely(ret >= iov_size)) {
2059                         ret = -ENOBUFS;
2060                         break;
2061                 }
2062
2063                 map = vhost_iotlb_itree_first(umem, addr, last);
2064                 if (map == NULL || map->start > addr) {
2065                         if (umem != dev->iotlb) {
2066                                 ret = -EFAULT;
2067                                 break;
2068                         }
2069                         ret = -EAGAIN;
2070                         break;
2071                 } else if (!(map->perm & access)) {
2072                         ret = -EPERM;
2073                         break;
2074                 }
2075
2076                 _iov = iov + ret;
2077                 size = map->size - addr + map->start;
2078                 _iov->iov_len = min((u64)len - s, size);
2079                 _iov->iov_base = (void __user *)(unsigned long)
2080                                  (map->addr + addr - map->start);
2081                 s += size;
2082                 addr += size;
2083                 ++ret;
2084         }
2085
2086         if (ret == -EAGAIN)
2087                 vhost_iotlb_miss(vq, addr, access);
2088         return ret;
2089 }
2090
2091 /* Each buffer in the virtqueues is actually a chain of descriptors.  This
2092  * function returns the next descriptor in the chain,
2093  * or -1U if we're at the end. */
2094 static unsigned next_desc(struct vhost_virtqueue *vq, struct vring_desc *desc)
2095 {
2096         unsigned int next;
2097
2098         /* If this descriptor says it doesn't chain, we're done. */
2099         if (!(desc->flags & cpu_to_vhost16(vq, VRING_DESC_F_NEXT)))
2100                 return -1U;
2101
2102         /* Check they're not leading us off end of descriptors. */
2103         next = vhost16_to_cpu(vq, READ_ONCE(desc->next));
2104         return next;
2105 }
2106
2107 static int get_indirect(struct vhost_virtqueue *vq,
2108                         struct iovec iov[], unsigned int iov_size,
2109                         unsigned int *out_num, unsigned int *in_num,
2110                         struct vhost_log *log, unsigned int *log_num,
2111                         struct vring_desc *indirect)
2112 {
2113         struct vring_desc desc;
2114         unsigned int i = 0, count, found = 0;
2115         u32 len = vhost32_to_cpu(vq, indirect->len);
2116         struct iov_iter from;
2117         int ret, access;
2118
2119         /* Sanity check */
2120         if (unlikely(len % sizeof desc)) {
2121                 vq_err(vq, "Invalid length in indirect descriptor: "
2122                        "len 0x%llx not multiple of 0x%zx\n",
2123                        (unsigned long long)len,
2124                        sizeof desc);
2125                 return -EINVAL;
2126         }
2127
2128         ret = translate_desc(vq, vhost64_to_cpu(vq, indirect->addr), len, vq->indirect,
2129                              UIO_MAXIOV, VHOST_ACCESS_RO);
2130         if (unlikely(ret < 0)) {
2131                 if (ret != -EAGAIN)
2132                         vq_err(vq, "Translation failure %d in indirect.\n", ret);
2133                 return ret;
2134         }
2135         iov_iter_init(&from, ITER_SOURCE, vq->indirect, ret, len);
2136         count = len / sizeof desc;
2137         /* Buffers are chained via a 16 bit next field, so
2138          * we can have at most 2^16 of these. */
2139         if (unlikely(count > USHRT_MAX + 1)) {
2140                 vq_err(vq, "Indirect buffer length too big: %d\n",
2141                        indirect->len);
2142                 return -E2BIG;
2143         }
2144
2145         do {
2146                 unsigned iov_count = *in_num + *out_num;
2147                 if (unlikely(++found > count)) {
2148                         vq_err(vq, "Loop detected: last one at %u "
2149                                "indirect size %u\n",
2150                                i, count);
2151                         return -EINVAL;
2152                 }
2153                 if (unlikely(!copy_from_iter_full(&desc, sizeof(desc), &from))) {
2154                         vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n",
2155                                i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
2156                         return -EINVAL;
2157                 }
2158                 if (unlikely(desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT))) {
2159                         vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n",
2160                                i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
2161                         return -EINVAL;
2162                 }
2163
2164                 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
2165                         access = VHOST_ACCESS_WO;
2166                 else
2167                         access = VHOST_ACCESS_RO;
2168
2169                 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
2170                                      vhost32_to_cpu(vq, desc.len), iov + iov_count,
2171                                      iov_size - iov_count, access);
2172                 if (unlikely(ret < 0)) {
2173                         if (ret != -EAGAIN)
2174                                 vq_err(vq, "Translation failure %d indirect idx %d\n",
2175                                         ret, i);
2176                         return ret;
2177                 }
2178                 /* If this is an input descriptor, increment that count. */
2179                 if (access == VHOST_ACCESS_WO) {
2180                         *in_num += ret;
2181                         if (unlikely(log && ret)) {
2182                                 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
2183                                 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
2184                                 ++*log_num;
2185                         }
2186                 } else {
2187                         /* If it's an output descriptor, they're all supposed
2188                          * to come before any input descriptors. */
2189                         if (unlikely(*in_num)) {
2190                                 vq_err(vq, "Indirect descriptor "
2191                                        "has out after in: idx %d\n", i);
2192                                 return -EINVAL;
2193                         }
2194                         *out_num += ret;
2195                 }
2196         } while ((i = next_desc(vq, &desc)) != -1);
2197         return 0;
2198 }
2199
2200 /* This looks in the virtqueue and for the first available buffer, and converts
2201  * it to an iovec for convenient access.  Since descriptors consist of some
2202  * number of output then some number of input descriptors, it's actually two
2203  * iovecs, but we pack them into one and note how many of each there were.
2204  *
2205  * This function returns the descriptor number found, or vq->num (which is
2206  * never a valid descriptor number) if none was found.  A negative code is
2207  * returned on error. */
2208 int vhost_get_vq_desc(struct vhost_virtqueue *vq,
2209                       struct iovec iov[], unsigned int iov_size,
2210                       unsigned int *out_num, unsigned int *in_num,
2211                       struct vhost_log *log, unsigned int *log_num)
2212 {
2213         struct vring_desc desc;
2214         unsigned int i, head, found = 0;
2215         u16 last_avail_idx;
2216         __virtio16 avail_idx;
2217         __virtio16 ring_head;
2218         int ret, access;
2219
2220         /* Check it isn't doing very strange things with descriptor numbers. */
2221         last_avail_idx = vq->last_avail_idx;
2222
2223         if (vq->avail_idx == vq->last_avail_idx) {
2224                 if (unlikely(vhost_get_avail_idx(vq, &avail_idx))) {
2225                         vq_err(vq, "Failed to access avail idx at %p\n",
2226                                 &vq->avail->idx);
2227                         return -EFAULT;
2228                 }
2229                 vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
2230
2231                 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
2232                         vq_err(vq, "Guest moved used index from %u to %u",
2233                                 last_avail_idx, vq->avail_idx);
2234                         return -EFAULT;
2235                 }
2236
2237                 /* If there's nothing new since last we looked, return
2238                  * invalid.
2239                  */
2240                 if (vq->avail_idx == last_avail_idx)
2241                         return vq->num;
2242
2243                 /* Only get avail ring entries after they have been
2244                  * exposed by guest.
2245                  */
2246                 smp_rmb();
2247         }
2248
2249         /* Grab the next descriptor number they're advertising, and increment
2250          * the index we've seen. */
2251         if (unlikely(vhost_get_avail_head(vq, &ring_head, last_avail_idx))) {
2252                 vq_err(vq, "Failed to read head: idx %d address %p\n",
2253                        last_avail_idx,
2254                        &vq->avail->ring[last_avail_idx % vq->num]);
2255                 return -EFAULT;
2256         }
2257
2258         head = vhost16_to_cpu(vq, ring_head);
2259
2260         /* If their number is silly, that's an error. */
2261         if (unlikely(head >= vq->num)) {
2262                 vq_err(vq, "Guest says index %u > %u is available",
2263                        head, vq->num);
2264                 return -EINVAL;
2265         }
2266
2267         /* When we start there are none of either input nor output. */
2268         *out_num = *in_num = 0;
2269         if (unlikely(log))
2270                 *log_num = 0;
2271
2272         i = head;
2273         do {
2274                 unsigned iov_count = *in_num + *out_num;
2275                 if (unlikely(i >= vq->num)) {
2276                         vq_err(vq, "Desc index is %u > %u, head = %u",
2277                                i, vq->num, head);
2278                         return -EINVAL;
2279                 }
2280                 if (unlikely(++found > vq->num)) {
2281                         vq_err(vq, "Loop detected: last one at %u "
2282                                "vq size %u head %u\n",
2283                                i, vq->num, head);
2284                         return -EINVAL;
2285                 }
2286                 ret = vhost_get_desc(vq, &desc, i);
2287                 if (unlikely(ret)) {
2288                         vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
2289                                i, vq->desc + i);
2290                         return -EFAULT;
2291                 }
2292                 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT)) {
2293                         ret = get_indirect(vq, iov, iov_size,
2294                                            out_num, in_num,
2295                                            log, log_num, &desc);
2296                         if (unlikely(ret < 0)) {
2297                                 if (ret != -EAGAIN)
2298                                         vq_err(vq, "Failure detected "
2299                                                 "in indirect descriptor at idx %d\n", i);
2300                                 return ret;
2301                         }
2302                         continue;
2303                 }
2304
2305                 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
2306                         access = VHOST_ACCESS_WO;
2307                 else
2308                         access = VHOST_ACCESS_RO;
2309                 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
2310                                      vhost32_to_cpu(vq, desc.len), iov + iov_count,
2311                                      iov_size - iov_count, access);
2312                 if (unlikely(ret < 0)) {
2313                         if (ret != -EAGAIN)
2314                                 vq_err(vq, "Translation failure %d descriptor idx %d\n",
2315                                         ret, i);
2316                         return ret;
2317                 }
2318                 if (access == VHOST_ACCESS_WO) {
2319                         /* If this is an input descriptor,
2320                          * increment that count. */
2321                         *in_num += ret;
2322                         if (unlikely(log && ret)) {
2323                                 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
2324                                 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
2325                                 ++*log_num;
2326                         }
2327                 } else {
2328                         /* If it's an output descriptor, they're all supposed
2329                          * to come before any input descriptors. */
2330                         if (unlikely(*in_num)) {
2331                                 vq_err(vq, "Descriptor has out after in: "
2332                                        "idx %d\n", i);
2333                                 return -EINVAL;
2334                         }
2335                         *out_num += ret;
2336                 }
2337         } while ((i = next_desc(vq, &desc)) != -1);
2338
2339         /* On success, increment avail index. */
2340         vq->last_avail_idx++;
2341
2342         /* Assume notifications from guest are disabled at this point,
2343          * if they aren't we would need to update avail_event index. */
2344         BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
2345         return head;
2346 }
2347 EXPORT_SYMBOL_GPL(vhost_get_vq_desc);
2348
2349 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
2350 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
2351 {
2352         vq->last_avail_idx -= n;
2353 }
2354 EXPORT_SYMBOL_GPL(vhost_discard_vq_desc);
2355
2356 /* After we've used one of their buffers, we tell them about it.  We'll then
2357  * want to notify the guest, using eventfd. */
2358 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
2359 {
2360         struct vring_used_elem heads = {
2361                 cpu_to_vhost32(vq, head),
2362                 cpu_to_vhost32(vq, len)
2363         };
2364
2365         return vhost_add_used_n(vq, &heads, 1);
2366 }
2367 EXPORT_SYMBOL_GPL(vhost_add_used);
2368
2369 static int __vhost_add_used_n(struct vhost_virtqueue *vq,
2370                             struct vring_used_elem *heads,
2371                             unsigned count)
2372 {
2373         vring_used_elem_t __user *used;
2374         u16 old, new;
2375         int start;
2376
2377         start = vq->last_used_idx & (vq->num - 1);
2378         used = vq->used->ring + start;
2379         if (vhost_put_used(vq, heads, start, count)) {
2380                 vq_err(vq, "Failed to write used");
2381                 return -EFAULT;
2382         }
2383         if (unlikely(vq->log_used)) {
2384                 /* Make sure data is seen before log. */
2385                 smp_wmb();
2386                 /* Log used ring entry write. */
2387                 log_used(vq, ((void __user *)used - (void __user *)vq->used),
2388                          count * sizeof *used);
2389         }
2390         old = vq->last_used_idx;
2391         new = (vq->last_used_idx += count);
2392         /* If the driver never bothers to signal in a very long while,
2393          * used index might wrap around. If that happens, invalidate
2394          * signalled_used index we stored. TODO: make sure driver
2395          * signals at least once in 2^16 and remove this. */
2396         if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old)))
2397                 vq->signalled_used_valid = false;
2398         return 0;
2399 }
2400
2401 /* After we've used one of their buffers, we tell them about it.  We'll then
2402  * want to notify the guest, using eventfd. */
2403 int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
2404                      unsigned count)
2405 {
2406         int start, n, r;
2407
2408         start = vq->last_used_idx & (vq->num - 1);
2409         n = vq->num - start;
2410         if (n < count) {
2411                 r = __vhost_add_used_n(vq, heads, n);
2412                 if (r < 0)
2413                         return r;
2414                 heads += n;
2415                 count -= n;
2416         }
2417         r = __vhost_add_used_n(vq, heads, count);
2418
2419         /* Make sure buffer is written before we update index. */
2420         smp_wmb();
2421         if (vhost_put_used_idx(vq)) {
2422                 vq_err(vq, "Failed to increment used idx");
2423                 return -EFAULT;
2424         }
2425         if (unlikely(vq->log_used)) {
2426                 /* Make sure used idx is seen before log. */
2427                 smp_wmb();
2428                 /* Log used index update. */
2429                 log_used(vq, offsetof(struct vring_used, idx),
2430                          sizeof vq->used->idx);
2431                 if (vq->log_ctx)
2432                         eventfd_signal(vq->log_ctx, 1);
2433         }
2434         return r;
2435 }
2436 EXPORT_SYMBOL_GPL(vhost_add_used_n);
2437
2438 static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2439 {
2440         __u16 old, new;
2441         __virtio16 event;
2442         bool v;
2443         /* Flush out used index updates. This is paired
2444          * with the barrier that the Guest executes when enabling
2445          * interrupts. */
2446         smp_mb();
2447
2448         if (vhost_has_feature(vq, VIRTIO_F_NOTIFY_ON_EMPTY) &&
2449             unlikely(vq->avail_idx == vq->last_avail_idx))
2450                 return true;
2451
2452         if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2453                 __virtio16 flags;
2454                 if (vhost_get_avail_flags(vq, &flags)) {
2455                         vq_err(vq, "Failed to get flags");
2456                         return true;
2457                 }
2458                 return !(flags & cpu_to_vhost16(vq, VRING_AVAIL_F_NO_INTERRUPT));
2459         }
2460         old = vq->signalled_used;
2461         v = vq->signalled_used_valid;
2462         new = vq->signalled_used = vq->last_used_idx;
2463         vq->signalled_used_valid = true;
2464
2465         if (unlikely(!v))
2466                 return true;
2467
2468         if (vhost_get_used_event(vq, &event)) {
2469                 vq_err(vq, "Failed to get used event idx");
2470                 return true;
2471         }
2472         return vring_need_event(vhost16_to_cpu(vq, event), new, old);
2473 }
2474
2475 /* This actually signals the guest, using eventfd. */
2476 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2477 {
2478         /* Signal the Guest tell them we used something up. */
2479         if (vq->call_ctx.ctx && vhost_notify(dev, vq))
2480                 eventfd_signal(vq->call_ctx.ctx, 1);
2481 }
2482 EXPORT_SYMBOL_GPL(vhost_signal);
2483
2484 /* And here's the combo meal deal.  Supersize me! */
2485 void vhost_add_used_and_signal(struct vhost_dev *dev,
2486                                struct vhost_virtqueue *vq,
2487                                unsigned int head, int len)
2488 {
2489         vhost_add_used(vq, head, len);
2490         vhost_signal(dev, vq);
2491 }
2492 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal);
2493
2494 /* multi-buffer version of vhost_add_used_and_signal */
2495 void vhost_add_used_and_signal_n(struct vhost_dev *dev,
2496                                  struct vhost_virtqueue *vq,
2497                                  struct vring_used_elem *heads, unsigned count)
2498 {
2499         vhost_add_used_n(vq, heads, count);
2500         vhost_signal(dev, vq);
2501 }
2502 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n);
2503
2504 /* return true if we're sure that avaiable ring is empty */
2505 bool vhost_vq_avail_empty(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2506 {
2507         __virtio16 avail_idx;
2508         int r;
2509
2510         if (vq->avail_idx != vq->last_avail_idx)
2511                 return false;
2512
2513         r = vhost_get_avail_idx(vq, &avail_idx);
2514         if (unlikely(r))
2515                 return false;
2516         vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
2517
2518         return vq->avail_idx == vq->last_avail_idx;
2519 }
2520 EXPORT_SYMBOL_GPL(vhost_vq_avail_empty);
2521
2522 /* OK, now we need to know about added descriptors. */
2523 bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2524 {
2525         __virtio16 avail_idx;
2526         int r;
2527
2528         if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
2529                 return false;
2530         vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
2531         if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2532                 r = vhost_update_used_flags(vq);
2533                 if (r) {
2534                         vq_err(vq, "Failed to enable notification at %p: %d\n",
2535                                &vq->used->flags, r);
2536                         return false;
2537                 }
2538         } else {
2539                 r = vhost_update_avail_event(vq);
2540                 if (r) {
2541                         vq_err(vq, "Failed to update avail event index at %p: %d\n",
2542                                vhost_avail_event(vq), r);
2543                         return false;
2544                 }
2545         }
2546         /* They could have slipped one in as we were doing that: make
2547          * sure it's written, then check again. */
2548         smp_mb();
2549         r = vhost_get_avail_idx(vq, &avail_idx);
2550         if (r) {
2551                 vq_err(vq, "Failed to check avail idx at %p: %d\n",
2552                        &vq->avail->idx, r);
2553                 return false;
2554         }
2555         vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
2556
2557         return vq->avail_idx != vq->last_avail_idx;
2558 }
2559 EXPORT_SYMBOL_GPL(vhost_enable_notify);
2560
2561 /* We don't need to be notified again. */
2562 void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2563 {
2564         int r;
2565
2566         if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
2567                 return;
2568         vq->used_flags |= VRING_USED_F_NO_NOTIFY;
2569         if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2570                 r = vhost_update_used_flags(vq);
2571                 if (r)
2572                         vq_err(vq, "Failed to disable notification at %p: %d\n",
2573                                &vq->used->flags, r);
2574         }
2575 }
2576 EXPORT_SYMBOL_GPL(vhost_disable_notify);
2577
2578 /* Create a new message. */
2579 struct vhost_msg_node *vhost_new_msg(struct vhost_virtqueue *vq, int type)
2580 {
2581         struct vhost_msg_node *node = kmalloc(sizeof *node, GFP_KERNEL);
2582         if (!node)
2583                 return NULL;
2584
2585         /* Make sure all padding within the structure is initialized. */
2586         memset(&node->msg, 0, sizeof node->msg);
2587         node->vq = vq;
2588         node->msg.type = type;
2589         return node;
2590 }
2591 EXPORT_SYMBOL_GPL(vhost_new_msg);
2592
2593 void vhost_enqueue_msg(struct vhost_dev *dev, struct list_head *head,
2594                        struct vhost_msg_node *node)
2595 {
2596         spin_lock(&dev->iotlb_lock);
2597         list_add_tail(&node->node, head);
2598         spin_unlock(&dev->iotlb_lock);
2599
2600         wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
2601 }
2602 EXPORT_SYMBOL_GPL(vhost_enqueue_msg);
2603
2604 struct vhost_msg_node *vhost_dequeue_msg(struct vhost_dev *dev,
2605                                          struct list_head *head)
2606 {
2607         struct vhost_msg_node *node = NULL;
2608
2609         spin_lock(&dev->iotlb_lock);
2610         if (!list_empty(head)) {
2611                 node = list_first_entry(head, struct vhost_msg_node,
2612                                         node);
2613                 list_del(&node->node);
2614         }
2615         spin_unlock(&dev->iotlb_lock);
2616
2617         return node;
2618 }
2619 EXPORT_SYMBOL_GPL(vhost_dequeue_msg);
2620
2621 void vhost_set_backend_features(struct vhost_dev *dev, u64 features)
2622 {
2623         struct vhost_virtqueue *vq;
2624         int i;
2625
2626         mutex_lock(&dev->mutex);
2627         for (i = 0; i < dev->nvqs; ++i) {
2628                 vq = dev->vqs[i];
2629                 mutex_lock(&vq->mutex);
2630                 vq->acked_backend_features = features;
2631                 mutex_unlock(&vq->mutex);
2632         }
2633         mutex_unlock(&dev->mutex);
2634 }
2635 EXPORT_SYMBOL_GPL(vhost_set_backend_features);
2636
2637 static int __init vhost_init(void)
2638 {
2639         return 0;
2640 }
2641
2642 static void __exit vhost_exit(void)
2643 {
2644 }
2645
2646 module_init(vhost_init);
2647 module_exit(vhost_exit);
2648
2649 MODULE_VERSION("0.0.1");
2650 MODULE_LICENSE("GPL v2");
2651 MODULE_AUTHOR("Michael S. Tsirkin");
2652 MODULE_DESCRIPTION("Host kernel accelerator for virtio");