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/cgroup.h>
  26 #include <linux/module.h>
  27 #include <linux/sort.h>
  28 #include <linux/sched/mm.h>
  29 #include <linux/sched/signal.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_work_flush(struct vhost_dev *dev, struct vhost_work *work)
 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_work_flush);
 247
 248 /* Flush any work that has been scheduled. When calling this, don't hold any
 249  * locks that are also used by the callback. */
 250 void vhost_poll_flush(struct vhost_poll *poll)
 251 {
 252         vhost_work_flush(poll->dev, &poll->work);
 253 }
 254 EXPORT_SYMBOL_GPL(vhost_poll_flush);
 255
 256 void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work)
 257 {
 258         if (!dev->worker)
 259                 return;
 260
 261         if (!test_and_set_bit(VHOST_WORK_QUEUED, &work->flags)) {
 262                 /* We can only add the work to the list after we're
 263                  * sure it was not in the list.
 264                  * test_and_set_bit() implies a memory barrier.
 265                  */
 266                 llist_add(&work->node, &dev->work_list);
 267                 wake_up_process(dev->worker);
 268         }
 269 }
 270 EXPORT_SYMBOL_GPL(vhost_work_queue);
 271
 272 /* A lockless hint for busy polling code to exit the loop */
 273 bool vhost_has_work(struct vhost_dev *dev)
 274 {
 275         return !llist_empty(&dev->work_list);
 276 }
 277 EXPORT_SYMBOL_GPL(vhost_has_work);
 278
 279 void vhost_poll_queue(struct vhost_poll *poll)
 280 {
 281         vhost_work_queue(poll->dev, &poll->work);
 282 }
 283 EXPORT_SYMBOL_GPL(vhost_poll_queue);
 284
 285 static void __vhost_vq_meta_reset(struct vhost_virtqueue *vq)
 286 {
 287         int j;
 288
 289         for (j = 0; j < VHOST_NUM_ADDRS; j++)
 290                 vq->meta_iotlb[j] = NULL;
 291 }
 292
 293 static void vhost_vq_meta_reset(struct vhost_dev *d)
 294 {
 295         int i;
 296
 297         for (i = 0; i < d->nvqs; ++i)
 298                 __vhost_vq_meta_reset(d->vqs[i]);
 299 }
 300
 301 static void vhost_vring_call_reset(struct vhost_vring_call *call_ctx)
 302 {
 303         call_ctx->ctx = NULL;
 304         memset(&call_ctx->producer, 0x0, sizeof(struct irq_bypass_producer));
 305 }
 306
 307 bool vhost_vq_is_setup(struct vhost_virtqueue *vq)
 308 {
 309         return vq->avail && vq->desc && vq->used && vhost_vq_access_ok(vq);
 310 }
 311 EXPORT_SYMBOL_GPL(vhost_vq_is_setup);
 312
 313 static void vhost_vq_reset(struct vhost_dev *dev,
 314                            struct vhost_virtqueue *vq)
 315 {
 316         vq->num = 1;
 317         vq->desc = NULL;
 318         vq->avail = NULL;
 319         vq->used = NULL;
 320         vq->last_avail_idx = 0;
 321         vq->avail_idx = 0;
 322         vq->last_used_idx = 0;
 323         vq->signalled_used = 0;
 324         vq->signalled_used_valid = false;
 325         vq->used_flags = 0;
 326         vq->log_used = false;
 327         vq->log_addr = -1ull;
 328         vq->private_data = NULL;
 329         vq->acked_features = 0;
 330         vq->acked_backend_features = 0;
 331         vq->log_base = NULL;
 332         vq->error_ctx = NULL;
 333         vq->kick = NULL;
 334         vq->log_ctx = NULL;
 335         vhost_disable_cross_endian(vq);
 336         vhost_reset_is_le(vq);
 337         vq->busyloop_timeout = 0;
 338         vq->umem = NULL;
 339         vq->iotlb = NULL;
 340         vhost_vring_call_reset(&vq->call_ctx);
 341         __vhost_vq_meta_reset(vq);
 342 }
 343
 344 static int vhost_worker(void *data)
 345 {
 346         struct vhost_dev *dev = data;
 347         struct vhost_work *work, *work_next;
 348         struct llist_node *node;
 349
 350         kthread_use_mm(dev->mm);
 351
 352         for (;;) {
 353                 /* mb paired w/ kthread_stop */
 354                 set_current_state(TASK_INTERRUPTIBLE);
 355
 356                 if (kthread_should_stop()) {
 357                         __set_current_state(TASK_RUNNING);
 358                         break;
 359                 }
 360
 361                 node = llist_del_all(&dev->work_list);
 362                 if (!node)
 363                         schedule();
 364
 365                 node = llist_reverse_order(node);
 366                 /* make sure flag is seen after deletion */
 367                 smp_wmb();
 368                 llist_for_each_entry_safe(work, work_next, node, node) {
 369                         clear_bit(VHOST_WORK_QUEUED, &work->flags);
 370                         __set_current_state(TASK_RUNNING);
 371                         kcov_remote_start_common(dev->kcov_handle);
 372                         work->fn(work);
 373                         kcov_remote_stop();
 374                         if (need_resched())
 375                                 schedule();
 376                 }
 377         }
 378         kthread_unuse_mm(dev->mm);
 379         return 0;
 380 }
 381
 382 static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq)
 383 {
 384         kfree(vq->indirect);
 385         vq->indirect = NULL;
 386         kfree(vq->log);
 387         vq->log = NULL;
 388         kfree(vq->heads);
 389         vq->heads = NULL;
 390 }
 391
 392 /* Helper to allocate iovec buffers for all vqs. */
 393 static long vhost_dev_alloc_iovecs(struct vhost_dev *dev)
 394 {
 395         struct vhost_virtqueue *vq;
 396         int i;
 397
 398         for (i = 0; i < dev->nvqs; ++i) {
 399                 vq = dev->vqs[i];
 400                 vq->indirect = kmalloc_array(UIO_MAXIOV,
 401                                              sizeof(*vq->indirect),
 402                                              GFP_KERNEL);
 403                 vq->log = kmalloc_array(dev->iov_limit, sizeof(*vq->log),
 404                                         GFP_KERNEL);
 405                 vq->heads = kmalloc_array(dev->iov_limit, sizeof(*vq->heads),
 406                                           GFP_KERNEL);
 407                 if (!vq->indirect || !vq->log || !vq->heads)
 408                         goto err_nomem;
 409         }
 410         return 0;
 411
 412 err_nomem:
 413         for (; i >= 0; --i)
 414                 vhost_vq_free_iovecs(dev->vqs[i]);
 415         return -ENOMEM;
 416 }
 417
 418 static void vhost_dev_free_iovecs(struct vhost_dev *dev)
 419 {
 420         int i;
 421
 422         for (i = 0; i < dev->nvqs; ++i)
 423                 vhost_vq_free_iovecs(dev->vqs[i]);
 424 }
 425
 426 bool vhost_exceeds_weight(struct vhost_virtqueue *vq,
 427                           int pkts, int total_len)
 428 {
 429         struct vhost_dev *dev = vq->dev;
 430
 431         if ((dev->byte_weight && total_len >= dev->byte_weight) ||
 432             pkts >= dev->weight) {
 433                 vhost_poll_queue(&vq->poll);
 434                 return true;
 435         }
 436
 437         return false;
 438 }
 439 EXPORT_SYMBOL_GPL(vhost_exceeds_weight);
 440
 441 static size_t vhost_get_avail_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->avail) +
 448                sizeof(*vq->avail->ring) * num + event;
 449 }
 450
 451 static size_t vhost_get_used_size(struct vhost_virtqueue *vq,
 452                                   unsigned int num)
 453 {
 454         size_t event __maybe_unused =
 455                vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
 456
 457         return sizeof(*vq->used) +
 458                sizeof(*vq->used->ring) * num + event;
 459 }
 460
 461 static size_t vhost_get_desc_size(struct vhost_virtqueue *vq,
 462                                   unsigned int num)
 463 {
 464         return sizeof(*vq->desc) * num;
 465 }
 466
 467 void vhost_dev_init(struct vhost_dev *dev,
 468                     struct vhost_virtqueue **vqs, int nvqs,
 469                     int iov_limit, int weight, int byte_weight,
 470                     bool use_worker,
 471                     int (*msg_handler)(struct vhost_dev *dev,
 472                                        struct vhost_iotlb_msg *msg))
 473 {
 474         struct vhost_virtqueue *vq;
 475         int i;
 476
 477         dev->vqs = vqs;
 478         dev->nvqs = nvqs;
 479         mutex_init(&dev->mutex);
 480         dev->log_ctx = NULL;
 481         dev->umem = NULL;
 482         dev->iotlb = NULL;
 483         dev->mm = NULL;
 484         dev->worker = NULL;
 485         dev->iov_limit = iov_limit;
 486         dev->weight = weight;
 487         dev->byte_weight = byte_weight;
 488         dev->use_worker = use_worker;
 489         dev->msg_handler = msg_handler;
 490         init_llist_head(&dev->work_list);
 491         init_waitqueue_head(&dev->wait);
 492         INIT_LIST_HEAD(&dev->read_list);
 493         INIT_LIST_HEAD(&dev->pending_list);
 494         spin_lock_init(&dev->iotlb_lock);
 495
 496
 497         for (i = 0; i < dev->nvqs; ++i) {
 498                 vq = dev->vqs[i];
 499                 vq->log = NULL;
 500                 vq->indirect = NULL;
 501                 vq->heads = NULL;
 502                 vq->dev = dev;
 503                 mutex_init(&vq->mutex);
 504                 vhost_vq_reset(dev, vq);
 505                 if (vq->handle_kick)
 506                         vhost_poll_init(&vq->poll, vq->handle_kick,
 507                                         EPOLLIN, dev);
 508         }
 509 }
 510 EXPORT_SYMBOL_GPL(vhost_dev_init);
 511
 512 /* Caller should have device mutex */
 513 long vhost_dev_check_owner(struct vhost_dev *dev)
 514 {
 515         /* Are you the owner? If not, I don't think you mean to do that */
 516         return dev->mm == current->mm ? 0 : -EPERM;
 517 }
 518 EXPORT_SYMBOL_GPL(vhost_dev_check_owner);
 519
 520 struct vhost_attach_cgroups_struct {
 521         struct vhost_work work;
 522         struct task_struct *owner;
 523         int ret;
 524 };
 525
 526 static void vhost_attach_cgroups_work(struct vhost_work *work)
 527 {
 528         struct vhost_attach_cgroups_struct *s;
 529
 530         s = container_of(work, struct vhost_attach_cgroups_struct, work);
 531         s->ret = cgroup_attach_task_all(s->owner, current);
 532 }
 533
 534 static int vhost_attach_cgroups(struct vhost_dev *dev)
 535 {
 536         struct vhost_attach_cgroups_struct attach;
 537
 538         attach.owner = current;
 539         vhost_work_init(&attach.work, vhost_attach_cgroups_work);
 540         vhost_work_queue(dev, &attach.work);
 541         vhost_work_flush(dev, &attach.work);
 542         return attach.ret;
 543 }
 544
 545 /* Caller should have device mutex */
 546 bool vhost_dev_has_owner(struct vhost_dev *dev)
 547 {
 548         return dev->mm;
 549 }
 550 EXPORT_SYMBOL_GPL(vhost_dev_has_owner);
 551
 552 static void vhost_attach_mm(struct vhost_dev *dev)
 553 {
 554         /* No owner, become one */
 555         if (dev->use_worker) {
 556                 dev->mm = get_task_mm(current);
 557         } else {
 558                 /* vDPA device does not use worker thead, so there's
 559                  * no need to hold the address space for mm. This help
 560                  * to avoid deadlock in the case of mmap() which may
 561                  * held the refcnt of the file and depends on release
 562                  * method to remove vma.
 563                  */
 564                 dev->mm = current->mm;
 565                 mmgrab(dev->mm);
 566         }
 567 }
 568
 569 static void vhost_detach_mm(struct vhost_dev *dev)
 570 {
 571         if (!dev->mm)
 572                 return;
 573
 574         if (dev->use_worker)
 575                 mmput(dev->mm);
 576         else
 577                 mmdrop(dev->mm);
 578
 579         dev->mm = NULL;
 580 }
 581
 582 /* Caller should have device mutex */
 583 long vhost_dev_set_owner(struct vhost_dev *dev)
 584 {
 585         struct task_struct *worker;
 586         int err;
 587
 588         /* Is there an owner already? */
 589         if (vhost_dev_has_owner(dev)) {
 590                 err = -EBUSY;
 591                 goto err_mm;
 592         }
 593
 594         vhost_attach_mm(dev);
 595
 596         dev->kcov_handle = kcov_common_handle();
 597         if (dev->use_worker) {
 598                 worker = kthread_create(vhost_worker, dev,
 599                                         "vhost-%d", current->pid);
 600                 if (IS_ERR(worker)) {
 601                         err = PTR_ERR(worker);
 602                         goto err_worker;
 603                 }
 604
 605                 dev->worker = worker;
 606                 wake_up_process(worker); /* avoid contributing to loadavg */
 607
 608                 err = vhost_attach_cgroups(dev);
 609                 if (err)
 610                         goto err_cgroup;
 611         }
 612
 613         err = vhost_dev_alloc_iovecs(dev);
 614         if (err)
 615                 goto err_cgroup;
 616
 617         return 0;
 618 err_cgroup:
 619         if (dev->worker) {
 620                 kthread_stop(dev->worker);
 621                 dev->worker = NULL;
 622         }
 623 err_worker:
 624         vhost_detach_mm(dev);
 625         dev->kcov_handle = 0;
 626 err_mm:
 627         return err;
 628 }
 629 EXPORT_SYMBOL_GPL(vhost_dev_set_owner);
 630
 631 static struct vhost_iotlb *iotlb_alloc(void)
 632 {
 633         return vhost_iotlb_alloc(max_iotlb_entries,
 634                                  VHOST_IOTLB_FLAG_RETIRE);
 635 }
 636
 637 struct vhost_iotlb *vhost_dev_reset_owner_prepare(void)
 638 {
 639         return iotlb_alloc();
 640 }
 641 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner_prepare);
 642
 643 /* Caller should have device mutex */
 644 void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_iotlb *umem)
 645 {
 646         int i;
 647
 648         vhost_dev_cleanup(dev);
 649
 650         dev->umem = umem;
 651         /* We don't need VQ locks below since vhost_dev_cleanup makes sure
 652          * VQs aren't running.
 653          */
 654         for (i = 0; i < dev->nvqs; ++i)
 655                 dev->vqs[i]->umem = umem;
 656 }
 657 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner);
 658
 659 void vhost_dev_stop(struct vhost_dev *dev)
 660 {
 661         int i;
 662
 663         for (i = 0; i < dev->nvqs; ++i) {
 664                 if (dev->vqs[i]->kick && dev->vqs[i]->handle_kick) {
 665                         vhost_poll_stop(&dev->vqs[i]->poll);
 666                         vhost_poll_flush(&dev->vqs[i]->poll);
 667                 }
 668         }
 669 }
 670 EXPORT_SYMBOL_GPL(vhost_dev_stop);
 671
 672 void vhost_clear_msg(struct vhost_dev *dev)
 673 {
 674         struct vhost_msg_node *node, *n;
 675
 676         spin_lock(&dev->iotlb_lock);
 677
 678         list_for_each_entry_safe(node, n, &dev->read_list, node) {
 679                 list_del(&node->node);
 680                 kfree(node);
 681         }
 682
 683         list_for_each_entry_safe(node, n, &dev->pending_list, node) {
 684                 list_del(&node->node);
 685                 kfree(node);
 686         }
 687
 688         spin_unlock(&dev->iotlb_lock);
 689 }
 690 EXPORT_SYMBOL_GPL(vhost_clear_msg);
 691
 692 void vhost_dev_cleanup(struct vhost_dev *dev)
 693 {
 694         int i;
 695
 696         for (i = 0; i < dev->nvqs; ++i) {
 697                 if (dev->vqs[i]->error_ctx)
 698                         eventfd_ctx_put(dev->vqs[i]->error_ctx);
 699                 if (dev->vqs[i]->kick)
 700                         fput(dev->vqs[i]->kick);
 701                 if (dev->vqs[i]->call_ctx.ctx)
 702                         eventfd_ctx_put(dev->vqs[i]->call_ctx.ctx);
 703                 vhost_vq_reset(dev, dev->vqs[i]);
 704         }
 705         vhost_dev_free_iovecs(dev);
 706         if (dev->log_ctx)
 707                 eventfd_ctx_put(dev->log_ctx);
 708         dev->log_ctx = NULL;
 709         /* No one will access memory at this point */
 710         vhost_iotlb_free(dev->umem);
 711         dev->umem = NULL;
 712         vhost_iotlb_free(dev->iotlb);
 713         dev->iotlb = NULL;
 714         vhost_clear_msg(dev);
 715         wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
 716         WARN_ON(!llist_empty(&dev->work_list));
 717         if (dev->worker) {
 718                 kthread_stop(dev->worker);
 719                 dev->worker = NULL;
 720                 dev->kcov_handle = 0;
 721         }
 722         vhost_detach_mm(dev);
 723 }
 724 EXPORT_SYMBOL_GPL(vhost_dev_cleanup);
 725
 726 static bool log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
 727 {
 728         u64 a = addr / VHOST_PAGE_SIZE / 8;
 729
 730         /* Make sure 64 bit math will not overflow. */
 731         if (a > ULONG_MAX - (unsigned long)log_base ||
 732             a + (unsigned long)log_base > ULONG_MAX)
 733                 return false;
 734
 735         return access_ok(log_base + a,
 736                          (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8);
 737 }
 738
 739 /* Make sure 64 bit math will not overflow. */
 740 static bool vhost_overflow(u64 uaddr, u64 size)
 741 {
 742         if (uaddr > ULONG_MAX || size > ULONG_MAX)
 743                 return true;
 744
 745         if (!size)
 746                 return false;
 747
 748         return uaddr > ULONG_MAX - size + 1;
 749 }
 750
 751 /* Caller should have vq mutex and device mutex. */
 752 static bool vq_memory_access_ok(void __user *log_base, struct vhost_iotlb *umem,
 753                                 int log_all)
 754 {
 755         struct vhost_iotlb_map *map;
 756
 757         if (!umem)
 758                 return false;
 759
 760         list_for_each_entry(map, &umem->list, link) {
 761                 unsigned long a = map->addr;
 762
 763                 if (vhost_overflow(map->addr, map->size))
 764                         return false;
 765
 766
 767                 if (!access_ok((void __user *)a, map->size))
 768                         return false;
 769                 else if (log_all && !log_access_ok(log_base,
 770                                                    map->start,
 771                                                    map->size))
 772                         return false;
 773         }
 774         return true;
 775 }
 776
 777 static inline void __user *vhost_vq_meta_fetch(struct vhost_virtqueue *vq,
 778                                                u64 addr, unsigned int size,
 779                                                int type)
 780 {
 781         const struct vhost_iotlb_map *map = vq->meta_iotlb[type];
 782
 783         if (!map)
 784                 return NULL;
 785
 786         return (void __user *)(uintptr_t)(map->addr + addr - map->start);
 787 }
 788
 789 /* Can we switch to this memory table? */
 790 /* Caller should have device mutex but not vq mutex */
 791 static bool memory_access_ok(struct vhost_dev *d, struct vhost_iotlb *umem,
 792                              int log_all)
 793 {
 794         int i;
 795
 796         for (i = 0; i < d->nvqs; ++i) {
 797                 bool ok;
 798                 bool log;
 799
 800                 mutex_lock(&d->vqs[i]->mutex);
 801                 log = log_all || vhost_has_feature(d->vqs[i], VHOST_F_LOG_ALL);
 802                 /* If ring is inactive, will check when it's enabled. */
 803                 if (d->vqs[i]->private_data)
 804                         ok = vq_memory_access_ok(d->vqs[i]->log_base,
 805                                                  umem, log);
 806                 else
 807                         ok = true;
 808                 mutex_unlock(&d->vqs[i]->mutex);
 809                 if (!ok)
 810                         return false;
 811         }
 812         return true;
 813 }
 814
 815 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
 816                           struct iovec iov[], int iov_size, int access);
 817
 818 static int vhost_copy_to_user(struct vhost_virtqueue *vq, void __user *to,
 819                               const void *from, unsigned size)
 820 {
 821         int ret;
 822
 823         if (!vq->iotlb)
 824                 return __copy_to_user(to, from, size);
 825         else {
 826                 /* This function should be called after iotlb
 827                  * prefetch, which means we're sure that all vq
 828                  * could be access through iotlb. So -EAGAIN should
 829                  * not happen in this case.
 830                  */
 831                 struct iov_iter t;
 832                 void __user *uaddr = vhost_vq_meta_fetch(vq,
 833                                      (u64)(uintptr_t)to, size,
 834                                      VHOST_ADDR_USED);
 835
 836                 if (uaddr)
 837                         return __copy_to_user(uaddr, from, size);
 838
 839                 ret = translate_desc(vq, (u64)(uintptr_t)to, size, vq->iotlb_iov,
 840                                      ARRAY_SIZE(vq->iotlb_iov),
 841                                      VHOST_ACCESS_WO);
 842                 if (ret < 0)
 843                         goto out;
 844                 iov_iter_init(&t, WRITE, vq->iotlb_iov, ret, size);
 845                 ret = copy_to_iter(from, size, &t);
 846                 if (ret == size)
 847                         ret = 0;
 848         }
 849 out:
 850         return ret;
 851 }
 852
 853 static int vhost_copy_from_user(struct vhost_virtqueue *vq, void *to,
 854                                 void __user *from, unsigned size)
 855 {
 856         int ret;
 857
 858         if (!vq->iotlb)
 859                 return __copy_from_user(to, from, size);
 860         else {
 861                 /* This function should be called after iotlb
 862                  * prefetch, which means we're sure that vq
 863                  * could be access through iotlb. So -EAGAIN should
 864                  * not happen in this case.
 865                  */
 866                 void __user *uaddr = vhost_vq_meta_fetch(vq,
 867                                      (u64)(uintptr_t)from, size,
 868                                      VHOST_ADDR_DESC);
 869                 struct iov_iter f;
 870
 871                 if (uaddr)
 872                         return __copy_from_user(to, uaddr, size);
 873
 874                 ret = translate_desc(vq, (u64)(uintptr_t)from, size, vq->iotlb_iov,
 875                                      ARRAY_SIZE(vq->iotlb_iov),
 876                                      VHOST_ACCESS_RO);
 877                 if (ret < 0) {
 878                         vq_err(vq, "IOTLB translation failure: uaddr "
 879                                "%p size 0x%llx\n", from,
 880                                (unsigned long long) size);
 881                         goto out;
 882                 }
 883                 iov_iter_init(&f, READ, vq->iotlb_iov, ret, size);
 884                 ret = copy_from_iter(to, size, &f);
 885                 if (ret == size)
 886                         ret = 0;
 887         }
 888
 889 out:
 890         return ret;
 891 }
 892
 893 static void __user *__vhost_get_user_slow(struct vhost_virtqueue *vq,
 894                                           void __user *addr, unsigned int size,
 895                                           int type)
 896 {
 897         int ret;
 898
 899         ret = translate_desc(vq, (u64)(uintptr_t)addr, size, vq->iotlb_iov,
 900                              ARRAY_SIZE(vq->iotlb_iov),
 901                              VHOST_ACCESS_RO);
 902         if (ret < 0) {
 903                 vq_err(vq, "IOTLB translation failure: uaddr "
 904                         "%p size 0x%llx\n", addr,
 905                         (unsigned long long) size);
 906                 return NULL;
 907         }
 908
 909         if (ret != 1 || vq->iotlb_iov[0].iov_len != size) {
 910                 vq_err(vq, "Non atomic userspace memory access: uaddr "
 911                         "%p size 0x%llx\n", addr,
 912                         (unsigned long long) size);
 913                 return NULL;
 914         }
 915
 916         return vq->iotlb_iov[0].iov_base;
 917 }
 918
 919 /* This function should be called after iotlb
 920  * prefetch, which means we're sure that vq
 921  * could be access through iotlb. So -EAGAIN should
 922  * not happen in this case.
 923  */
 924 static inline void __user *__vhost_get_user(struct vhost_virtqueue *vq,
 925                                             void __user *addr, unsigned int size,
 926                                             int type)
 927 {
 928         void __user *uaddr = vhost_vq_meta_fetch(vq,
 929                              (u64)(uintptr_t)addr, size, type);
 930         if (uaddr)
 931                 return uaddr;
 932
 933         return __vhost_get_user_slow(vq, addr, size, type);
 934 }
 935
 936 #define vhost_put_user(vq, x, ptr)              \
 937 ({ \
 938         int ret; \
 939         if (!vq->iotlb) { \
 940                 ret = __put_user(x, ptr); \
 941         } else { \
 942                 __typeof__(ptr) to = \
 943                         (__typeof__(ptr)) __vhost_get_user(vq, ptr,     \
 944                                           sizeof(*ptr), VHOST_ADDR_USED); \
 945                 if (to != NULL) \
 946                         ret = __put_user(x, to); \
 947                 else \
 948                         ret = -EFAULT;  \
 949         } \
 950         ret; \
 951 })
 952
 953 static inline int vhost_put_avail_event(struct vhost_virtqueue *vq)
 954 {
 955         return vhost_put_user(vq, cpu_to_vhost16(vq, vq->avail_idx),
 956                               vhost_avail_event(vq));
 957 }
 958
 959 static inline int vhost_put_used(struct vhost_virtqueue *vq,
 960                                  struct vring_used_elem *head, int idx,
 961                                  int count)
 962 {
 963         return vhost_copy_to_user(vq, vq->used->ring + idx, head,
 964                                   count * sizeof(*head));
 965 }
 966
 967 static inline int vhost_put_used_flags(struct vhost_virtqueue *vq)
 968
 969 {
 970         return vhost_put_user(vq, cpu_to_vhost16(vq, vq->used_flags),
 971                               &vq->used->flags);
 972 }
 973
 974 static inline int vhost_put_used_idx(struct vhost_virtqueue *vq)
 975
 976 {
 977         return vhost_put_user(vq, cpu_to_vhost16(vq, vq->last_used_idx),
 978                               &vq->used->idx);
 979 }
 980
 981 #define vhost_get_user(vq, x, ptr, type)                \
 982 ({ \
 983         int ret; \
 984         if (!vq->iotlb) { \
 985                 ret = __get_user(x, ptr); \
 986         } else { \
 987                 __typeof__(ptr) from = \
 988                         (__typeof__(ptr)) __vhost_get_user(vq, ptr, \
 989                                                            sizeof(*ptr), \
 990                                                            type); \
 991                 if (from != NULL) \
 992                         ret = __get_user(x, from); \
 993                 else \
 994                         ret = -EFAULT; \
 995         } \
 996         ret; \
 997 })
 998
 999 #define vhost_get_avail(vq, x, ptr) \
1000         vhost_get_user(vq, x, ptr, VHOST_ADDR_AVAIL)
1001
1002 #define vhost_get_used(vq, x, ptr) \
1003         vhost_get_user(vq, x, ptr, VHOST_ADDR_USED)
1004
1005 static void vhost_dev_lock_vqs(struct vhost_dev *d)
1006 {
1007         int i = 0;
1008         for (i = 0; i < d->nvqs; ++i)
1009                 mutex_lock_nested(&d->vqs[i]->mutex, i);
1010 }
1011
1012 static void vhost_dev_unlock_vqs(struct vhost_dev *d)
1013 {
1014         int i = 0;
1015         for (i = 0; i < d->nvqs; ++i)
1016                 mutex_unlock(&d->vqs[i]->mutex);
1017 }
1018
1019 static inline int vhost_get_avail_idx(struct vhost_virtqueue *vq,
1020                                       __virtio16 *idx)
1021 {
1022         return vhost_get_avail(vq, *idx, &vq->avail->idx);
1023 }
1024
1025 static inline int vhost_get_avail_head(struct vhost_virtqueue *vq,
1026                                        __virtio16 *head, int idx)
1027 {
1028         return vhost_get_avail(vq, *head,
1029                                &vq->avail->ring[idx & (vq->num - 1)]);
1030 }
1031
1032 static inline int vhost_get_avail_flags(struct vhost_virtqueue *vq,
1033                                         __virtio16 *flags)
1034 {
1035         return vhost_get_avail(vq, *flags, &vq->avail->flags);
1036 }
1037
1038 static inline int vhost_get_used_event(struct vhost_virtqueue *vq,
1039                                        __virtio16 *event)
1040 {
1041         return vhost_get_avail(vq, *event, vhost_used_event(vq));
1042 }
1043
1044 static inline int vhost_get_used_idx(struct vhost_virtqueue *vq,
1045                                      __virtio16 *idx)
1046 {
1047         return vhost_get_used(vq, *idx, &vq->used->idx);
1048 }
1049
1050 static inline int vhost_get_desc(struct vhost_virtqueue *vq,
1051                                  struct vring_desc *desc, int idx)
1052 {
1053         return vhost_copy_from_user(vq, desc, vq->desc + idx, sizeof(*desc));
1054 }
1055
1056 static void vhost_iotlb_notify_vq(struct vhost_dev *d,
1057                                   struct vhost_iotlb_msg *msg)
1058 {
1059         struct vhost_msg_node *node, *n;
1060
1061         spin_lock(&d->iotlb_lock);
1062
1063         list_for_each_entry_safe(node, n, &d->pending_list, node) {
1064                 struct vhost_iotlb_msg *vq_msg = &node->msg.iotlb;
1065                 if (msg->iova <= vq_msg->iova &&
1066                     msg->iova + msg->size - 1 >= vq_msg->iova &&
1067                     vq_msg->type == VHOST_IOTLB_MISS) {
1068                         vhost_poll_queue(&node->vq->poll);
1069                         list_del(&node->node);
1070                         kfree(node);
1071                 }
1072         }
1073
1074         spin_unlock(&d->iotlb_lock);
1075 }
1076
1077 static bool umem_access_ok(u64 uaddr, u64 size, int access)
1078 {
1079         unsigned long a = uaddr;
1080
1081         /* Make sure 64 bit math will not overflow. */
1082         if (vhost_overflow(uaddr, size))
1083                 return false;
1084
1085         if ((access & VHOST_ACCESS_RO) &&
1086             !access_ok((void __user *)a, size))
1087                 return false;
1088         if ((access & VHOST_ACCESS_WO) &&
1089             !access_ok((void __user *)a, size))
1090                 return false;
1091         return true;
1092 }
1093
1094 static int vhost_process_iotlb_msg(struct vhost_dev *dev,
1095                                    struct vhost_iotlb_msg *msg)
1096 {
1097         int ret = 0;
1098
1099         mutex_lock(&dev->mutex);
1100         vhost_dev_lock_vqs(dev);
1101         switch (msg->type) {
1102         case VHOST_IOTLB_UPDATE:
1103                 if (!dev->iotlb) {
1104                         ret = -EFAULT;
1105                         break;
1106                 }
1107                 if (!umem_access_ok(msg->uaddr, msg->size, msg->perm)) {
1108                         ret = -EFAULT;
1109                         break;
1110                 }
1111                 vhost_vq_meta_reset(dev);
1112                 if (vhost_iotlb_add_range(dev->iotlb, msg->iova,
1113                                           msg->iova + msg->size - 1,
1114                                           msg->uaddr, msg->perm)) {
1115                         ret = -ENOMEM;
1116                         break;
1117                 }
1118                 vhost_iotlb_notify_vq(dev, msg);
1119                 break;
1120         case VHOST_IOTLB_INVALIDATE:
1121                 if (!dev->iotlb) {
1122                         ret = -EFAULT;
1123                         break;
1124                 }
1125                 vhost_vq_meta_reset(dev);
1126                 vhost_iotlb_del_range(dev->iotlb, msg->iova,
1127                                       msg->iova + msg->size - 1);
1128                 break;
1129         default:
1130                 ret = -EINVAL;
1131                 break;
1132         }
1133
1134         vhost_dev_unlock_vqs(dev);
1135         mutex_unlock(&dev->mutex);
1136
1137         return ret;
1138 }
1139 ssize_t vhost_chr_write_iter(struct vhost_dev *dev,
1140                              struct iov_iter *from)
1141 {
1142         struct vhost_iotlb_msg msg;
1143         size_t offset;
1144         int type, ret;
1145
1146         ret = copy_from_iter(&type, sizeof(type), from);
1147         if (ret != sizeof(type)) {
1148                 ret = -EINVAL;
1149                 goto done;
1150         }
1151
1152         switch (type) {
1153         case VHOST_IOTLB_MSG:
1154                 /* There maybe a hole after type for V1 message type,
1155                  * so skip it here.
1156                  */
1157                 offset = offsetof(struct vhost_msg, iotlb) - sizeof(int);
1158                 break;
1159         case VHOST_IOTLB_MSG_V2:
1160                 offset = sizeof(__u32);
1161                 break;
1162         default:
1163                 ret = -EINVAL;
1164                 goto done;
1165         }
1166
1167         iov_iter_advance(from, offset);
1168         ret = copy_from_iter(&msg, sizeof(msg), from);
1169         if (ret != sizeof(msg)) {
1170                 ret = -EINVAL;
1171                 goto done;
1172         }
1173
1174         if (dev->msg_handler)
1175                 ret = dev->msg_handler(dev, &msg);
1176         else
1177                 ret = vhost_process_iotlb_msg(dev, &msg);
1178         if (ret) {
1179                 ret = -EFAULT;
1180                 goto done;
1181         }
1182
1183         ret = (type == VHOST_IOTLB_MSG) ? sizeof(struct vhost_msg) :
1184               sizeof(struct vhost_msg_v2);
1185 done:
1186         return ret;
1187 }
1188 EXPORT_SYMBOL(vhost_chr_write_iter);
1189
1190 __poll_t vhost_chr_poll(struct file *file, struct vhost_dev *dev,
1191                             poll_table *wait)
1192 {
1193         __poll_t mask = 0;
1194
1195         poll_wait(file, &dev->wait, wait);
1196
1197         if (!list_empty(&dev->read_list))
1198                 mask |= EPOLLIN | EPOLLRDNORM;
1199
1200         return mask;
1201 }
1202 EXPORT_SYMBOL(vhost_chr_poll);
1203
1204 ssize_t vhost_chr_read_iter(struct vhost_dev *dev, struct iov_iter *to,
1205                             int noblock)
1206 {
1207         DEFINE_WAIT(wait);
1208         struct vhost_msg_node *node;
1209         ssize_t ret = 0;
1210         unsigned size = sizeof(struct vhost_msg);
1211
1212         if (iov_iter_count(to) < size)
1213                 return 0;
1214
1215         while (1) {
1216                 if (!noblock)
1217                         prepare_to_wait(&dev->wait, &wait,
1218                                         TASK_INTERRUPTIBLE);
1219
1220                 node = vhost_dequeue_msg(dev, &dev->read_list);
1221                 if (node)
1222                         break;
1223                 if (noblock) {
1224                         ret = -EAGAIN;
1225                         break;
1226                 }
1227                 if (signal_pending(current)) {
1228                         ret = -ERESTARTSYS;
1229                         break;
1230                 }
1231                 if (!dev->iotlb) {
1232                         ret = -EBADFD;
1233                         break;
1234                 }
1235
1236                 schedule();
1237         }
1238
1239         if (!noblock)
1240                 finish_wait(&dev->wait, &wait);
1241
1242         if (node) {
1243                 struct vhost_iotlb_msg *msg;
1244                 void *start = &node->msg;
1245
1246                 switch (node->msg.type) {
1247                 case VHOST_IOTLB_MSG:
1248                         size = sizeof(node->msg);
1249                         msg = &node->msg.iotlb;
1250                         break;
1251                 case VHOST_IOTLB_MSG_V2:
1252                         size = sizeof(node->msg_v2);
1253                         msg = &node->msg_v2.iotlb;
1254                         break;
1255                 default:
1256                         BUG();
1257                         break;
1258                 }
1259
1260                 ret = copy_to_iter(start, size, to);
1261                 if (ret != size || msg->type != VHOST_IOTLB_MISS) {
1262                         kfree(node);
1263                         return ret;
1264                 }
1265                 vhost_enqueue_msg(dev, &dev->pending_list, node);
1266         }
1267
1268         return ret;
1269 }
1270 EXPORT_SYMBOL_GPL(vhost_chr_read_iter);
1271
1272 static int vhost_iotlb_miss(struct vhost_virtqueue *vq, u64 iova, int access)
1273 {
1274         struct vhost_dev *dev = vq->dev;
1275         struct vhost_msg_node *node;
1276         struct vhost_iotlb_msg *msg;
1277         bool v2 = vhost_backend_has_feature(vq, VHOST_BACKEND_F_IOTLB_MSG_V2);
1278
1279         node = vhost_new_msg(vq, v2 ? VHOST_IOTLB_MSG_V2 : VHOST_IOTLB_MSG);
1280         if (!node)
1281                 return -ENOMEM;
1282
1283         if (v2) {
1284                 node->msg_v2.type = VHOST_IOTLB_MSG_V2;
1285                 msg = &node->msg_v2.iotlb;
1286         } else {
1287                 msg = &node->msg.iotlb;
1288         }
1289
1290         msg->type = VHOST_IOTLB_MISS;
1291         msg->iova = iova;
1292         msg->perm = access;
1293
1294         vhost_enqueue_msg(dev, &dev->read_list, node);
1295
1296         return 0;
1297 }
1298
1299 static bool vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
1300                          vring_desc_t __user *desc,
1301                          vring_avail_t __user *avail,
1302                          vring_used_t __user *used)
1303
1304 {
1305         /* If an IOTLB device is present, the vring addresses are
1306          * GIOVAs. Access validation occurs at prefetch time. */
1307         if (vq->iotlb)
1308                 return true;
1309
1310         return access_ok(desc, vhost_get_desc_size(vq, num)) &&
1311                access_ok(avail, vhost_get_avail_size(vq, num)) &&
1312                access_ok(used, vhost_get_used_size(vq, num));
1313 }
1314
1315 static void vhost_vq_meta_update(struct vhost_virtqueue *vq,
1316                                  const struct vhost_iotlb_map *map,
1317                                  int type)
1318 {
1319         int access = (type == VHOST_ADDR_USED) ?
1320                      VHOST_ACCESS_WO : VHOST_ACCESS_RO;
1321
1322         if (likely(map->perm & access))
1323                 vq->meta_iotlb[type] = map;
1324 }
1325
1326 static bool iotlb_access_ok(struct vhost_virtqueue *vq,
1327                             int access, u64 addr, u64 len, int type)
1328 {
1329         const struct vhost_iotlb_map *map;
1330         struct vhost_iotlb *umem = vq->iotlb;
1331         u64 s = 0, size, orig_addr = addr, last = addr + len - 1;
1332
1333         if (vhost_vq_meta_fetch(vq, addr, len, type))
1334                 return true;
1335
1336         while (len > s) {
1337                 map = vhost_iotlb_itree_first(umem, addr, last);
1338                 if (map == NULL || map->start > addr) {
1339                         vhost_iotlb_miss(vq, addr, access);
1340                         return false;
1341                 } else if (!(map->perm & access)) {
1342                         /* Report the possible access violation by
1343                          * request another translation from userspace.
1344                          */
1345                         return false;
1346                 }
1347
1348                 size = map->size - addr + map->start;
1349
1350                 if (orig_addr == addr && size >= len)
1351                         vhost_vq_meta_update(vq, map, type);
1352
1353                 s += size;
1354                 addr += size;
1355         }
1356
1357         return true;
1358 }
1359
1360 int vq_meta_prefetch(struct vhost_virtqueue *vq)
1361 {
1362         unsigned int num = vq->num;
1363
1364         if (!vq->iotlb)
1365                 return 1;
1366
1367         return iotlb_access_ok(vq, VHOST_MAP_RO, (u64)(uintptr_t)vq->desc,
1368                                vhost_get_desc_size(vq, num), VHOST_ADDR_DESC) &&
1369                iotlb_access_ok(vq, VHOST_MAP_RO, (u64)(uintptr_t)vq->avail,
1370                                vhost_get_avail_size(vq, num),
1371                                VHOST_ADDR_AVAIL) &&
1372                iotlb_access_ok(vq, VHOST_MAP_WO, (u64)(uintptr_t)vq->used,
1373                                vhost_get_used_size(vq, num), VHOST_ADDR_USED);
1374 }
1375 EXPORT_SYMBOL_GPL(vq_meta_prefetch);
1376
1377 /* Can we log writes? */
1378 /* Caller should have device mutex but not vq mutex */
1379 bool vhost_log_access_ok(struct vhost_dev *dev)
1380 {
1381         return memory_access_ok(dev, dev->umem, 1);
1382 }
1383 EXPORT_SYMBOL_GPL(vhost_log_access_ok);
1384
1385 static bool vq_log_used_access_ok(struct vhost_virtqueue *vq,
1386                                   void __user *log_base,
1387                                   bool log_used,
1388                                   u64 log_addr)
1389 {
1390         /* If an IOTLB device is present, log_addr is a GIOVA that
1391          * will never be logged by log_used(). */
1392         if (vq->iotlb)
1393                 return true;
1394
1395         return !log_used || log_access_ok(log_base, log_addr,
1396                                           vhost_get_used_size(vq, vq->num));
1397 }
1398
1399 /* Verify access for write logging. */
1400 /* Caller should have vq mutex and device mutex */
1401 static bool vq_log_access_ok(struct vhost_virtqueue *vq,
1402                              void __user *log_base)
1403 {
1404         return vq_memory_access_ok(log_base, vq->umem,
1405                                    vhost_has_feature(vq, VHOST_F_LOG_ALL)) &&
1406                 vq_log_used_access_ok(vq, log_base, vq->log_used, vq->log_addr);
1407 }
1408
1409 /* Can we start vq? */
1410 /* Caller should have vq mutex and device mutex */
1411 bool vhost_vq_access_ok(struct vhost_virtqueue *vq)
1412 {
1413         if (!vq_log_access_ok(vq, vq->log_base))
1414                 return false;
1415
1416         return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used);
1417 }
1418 EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
1419
1420 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
1421 {
1422         struct vhost_memory mem, *newmem;
1423         struct vhost_memory_region *region;
1424         struct vhost_iotlb *newumem, *oldumem;
1425         unsigned long size = offsetof(struct vhost_memory, regions);
1426         int i;
1427
1428         if (copy_from_user(&mem, m, size))
1429                 return -EFAULT;
1430         if (mem.padding)
1431                 return -EOPNOTSUPP;
1432         if (mem.nregions > max_mem_regions)
1433                 return -E2BIG;
1434         newmem = kvzalloc(struct_size(newmem, regions, mem.nregions),
1435                         GFP_KERNEL);
1436         if (!newmem)
1437                 return -ENOMEM;
1438
1439         memcpy(newmem, &mem, size);
1440         if (copy_from_user(newmem->regions, m->regions,
1441                            flex_array_size(newmem, regions, mem.nregions))) {
1442                 kvfree(newmem);
1443                 return -EFAULT;
1444         }
1445
1446         newumem = iotlb_alloc();
1447         if (!newumem) {
1448                 kvfree(newmem);
1449                 return -ENOMEM;
1450         }
1451
1452         for (region = newmem->regions;
1453              region < newmem->regions + mem.nregions;
1454              region++) {
1455                 if (vhost_iotlb_add_range(newumem,
1456                                           region->guest_phys_addr,
1457                                           region->guest_phys_addr +
1458                                           region->memory_size - 1,
1459                                           region->userspace_addr,
1460                                           VHOST_MAP_RW))
1461                         goto err;
1462         }
1463
1464         if (!memory_access_ok(d, newumem, 0))
1465                 goto err;
1466
1467         oldumem = d->umem;
1468         d->umem = newumem;
1469
1470         /* All memory accesses are done under some VQ mutex. */
1471         for (i = 0; i < d->nvqs; ++i) {
1472                 mutex_lock(&d->vqs[i]->mutex);
1473                 d->vqs[i]->umem = newumem;
1474                 mutex_unlock(&d->vqs[i]->mutex);
1475         }
1476
1477         kvfree(newmem);
1478         vhost_iotlb_free(oldumem);
1479         return 0;
1480
1481 err:
1482         vhost_iotlb_free(newumem);
1483         kvfree(newmem);
1484         return -EFAULT;
1485 }
1486
1487 static long vhost_vring_set_num(struct vhost_dev *d,
1488                                 struct vhost_virtqueue *vq,
1489                                 void __user *argp)
1490 {
1491         struct vhost_vring_state s;
1492
1493         /* Resizing ring with an active backend?
1494          * You don't want to do that. */
1495         if (vq->private_data)
1496                 return -EBUSY;
1497
1498         if (copy_from_user(&s, argp, sizeof s))
1499                 return -EFAULT;
1500
1501         if (!s.num || s.num > 0xffff || (s.num & (s.num - 1)))
1502                 return -EINVAL;
1503         vq->num = s.num;
1504
1505         return 0;
1506 }
1507
1508 static long vhost_vring_set_addr(struct vhost_dev *d,
1509                                  struct vhost_virtqueue *vq,
1510                                  void __user *argp)
1511 {
1512         struct vhost_vring_addr a;
1513
1514         if (copy_from_user(&a, argp, sizeof a))
1515                 return -EFAULT;
1516         if (a.flags & ~(0x1 << VHOST_VRING_F_LOG))
1517                 return -EOPNOTSUPP;
1518
1519         /* For 32bit, verify that the top 32bits of the user
1520            data are set to zero. */
1521         if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr ||
1522             (u64)(unsigned long)a.used_user_addr != a.used_user_addr ||
1523             (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr)
1524                 return -EFAULT;
1525
1526         /* Make sure it's safe to cast pointers to vring types. */
1527         BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE);
1528         BUILD_BUG_ON(__alignof__ *vq->used > VRING_USED_ALIGN_SIZE);
1529         if ((a.avail_user_addr & (VRING_AVAIL_ALIGN_SIZE - 1)) ||
1530             (a.used_user_addr & (VRING_USED_ALIGN_SIZE - 1)) ||
1531             (a.log_guest_addr & (VRING_USED_ALIGN_SIZE - 1)))
1532                 return -EINVAL;
1533
1534         /* We only verify access here if backend is configured.
1535          * If it is not, we don't as size might not have been setup.
1536          * We will verify when backend is configured. */
1537         if (vq->private_data) {
1538                 if (!vq_access_ok(vq, vq->num,
1539                         (void __user *)(unsigned long)a.desc_user_addr,
1540                         (void __user *)(unsigned long)a.avail_user_addr,
1541                         (void __user *)(unsigned long)a.used_user_addr))
1542                         return -EINVAL;
1543
1544                 /* Also validate log access for used ring if enabled. */
1545                 if (!vq_log_used_access_ok(vq, vq->log_base,
1546                                 a.flags & (0x1 << VHOST_VRING_F_LOG),
1547                                 a.log_guest_addr))
1548                         return -EINVAL;
1549         }
1550
1551         vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
1552         vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
1553         vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
1554         vq->log_addr = a.log_guest_addr;
1555         vq->used = (void __user *)(unsigned long)a.used_user_addr;
1556
1557         return 0;
1558 }
1559
1560 static long vhost_vring_set_num_addr(struct vhost_dev *d,
1561                                      struct vhost_virtqueue *vq,
1562                                      unsigned int ioctl,
1563                                      void __user *argp)
1564 {
1565         long r;
1566
1567         mutex_lock(&vq->mutex);
1568
1569         switch (ioctl) {
1570         case VHOST_SET_VRING_NUM:
1571                 r = vhost_vring_set_num(d, vq, argp);
1572                 break;
1573         case VHOST_SET_VRING_ADDR:
1574                 r = vhost_vring_set_addr(d, vq, argp);
1575                 break;
1576         default:
1577                 BUG();
1578         }
1579
1580         mutex_unlock(&vq->mutex);
1581
1582         return r;
1583 }
1584 long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
1585 {
1586         struct file *eventfp, *filep = NULL;
1587         bool pollstart = false, pollstop = false;
1588         struct eventfd_ctx *ctx = NULL;
1589         u32 __user *idxp = argp;
1590         struct vhost_virtqueue *vq;
1591         struct vhost_vring_state s;
1592         struct vhost_vring_file f;
1593         u32 idx;
1594         long r;
1595
1596         r = get_user(idx, idxp);
1597         if (r < 0)
1598                 return r;
1599         if (idx >= d->nvqs)
1600                 return -ENOBUFS;
1601
1602         idx = array_index_nospec(idx, d->nvqs);
1603         vq = d->vqs[idx];
1604
1605         if (ioctl == VHOST_SET_VRING_NUM ||
1606             ioctl == VHOST_SET_VRING_ADDR) {
1607                 return vhost_vring_set_num_addr(d, vq, ioctl, argp);
1608         }
1609
1610         mutex_lock(&vq->mutex);
1611
1612         switch (ioctl) {
1613         case VHOST_SET_VRING_BASE:
1614                 /* Moving base with an active backend?
1615                  * You don't want to do that. */
1616                 if (vq->private_data) {
1617                         r = -EBUSY;
1618                         break;
1619                 }
1620                 if (copy_from_user(&s, argp, sizeof s)) {
1621                         r = -EFAULT;
1622                         break;
1623                 }
1624                 if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) {
1625                         vq->last_avail_idx = s.num & 0xffff;
1626                         vq->last_used_idx = (s.num >> 16) & 0xffff;
1627                 } else {
1628                         if (s.num > 0xffff) {
1629                                 r = -EINVAL;
1630                                 break;
1631                         }
1632                         vq->last_avail_idx = s.num;
1633                 }
1634                 /* Forget the cached index value. */
1635                 vq->avail_idx = vq->last_avail_idx;
1636                 break;
1637         case VHOST_GET_VRING_BASE:
1638                 s.index = idx;
1639                 if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED))
1640                         s.num = (u32)vq->last_avail_idx | ((u32)vq->last_used_idx << 16);
1641                 else
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_poll_flush(&vq->poll);
1725         return r;
1726 }
1727 EXPORT_SYMBOL_GPL(vhost_vring_ioctl);
1728
1729 int vhost_init_device_iotlb(struct vhost_dev *d, bool enabled)
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/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, u16 avail_event)
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, READ, 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
2517         vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
2518         if (vq->avail_idx != vq->last_avail_idx) {
2519                 /* Since we have updated avail_idx, the following
2520                  * call to vhost_get_vq_desc() will read available
2521                  * ring entries. Make sure that read happens after
2522                  * the avail_idx read.
2523                  */
2524                 smp_rmb();
2525                 return false;
2526         }
2527
2528         return true;
2529 }
2530 EXPORT_SYMBOL_GPL(vhost_vq_avail_empty);
2531
2532 /* OK, now we need to know about added descriptors. */
2533 bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2534 {
2535         __virtio16 avail_idx;
2536         int r;
2537
2538         if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
2539                 return false;
2540         vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
2541         if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2542                 r = vhost_update_used_flags(vq);
2543                 if (r) {
2544                         vq_err(vq, "Failed to enable notification at %p: %d\n",
2545                                &vq->used->flags, r);
2546                         return false;
2547                 }
2548         } else {
2549                 r = vhost_update_avail_event(vq, vq->avail_idx);
2550                 if (r) {
2551                         vq_err(vq, "Failed to update avail event index at %p: %d\n",
2552                                vhost_avail_event(vq), r);
2553                         return false;
2554                 }
2555         }
2556         /* They could have slipped one in as we were doing that: make
2557          * sure it's written, then check again. */
2558         smp_mb();
2559         r = vhost_get_avail_idx(vq, &avail_idx);
2560         if (r) {
2561                 vq_err(vq, "Failed to check avail idx at %p: %d\n",
2562                        &vq->avail->idx, r);
2563                 return false;
2564         }
2565
2566         return vhost16_to_cpu(vq, avail_idx) != vq->avail_idx;
2567 }
2568 EXPORT_SYMBOL_GPL(vhost_enable_notify);
2569
2570 /* We don't need to be notified again. */
2571 void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2572 {
2573         int r;
2574
2575         if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
2576                 return;
2577         vq->used_flags |= VRING_USED_F_NO_NOTIFY;
2578         if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2579                 r = vhost_update_used_flags(vq);
2580                 if (r)
2581                         vq_err(vq, "Failed to disable notification at %p: %d\n",
2582                                &vq->used->flags, r);
2583         }
2584 }
2585 EXPORT_SYMBOL_GPL(vhost_disable_notify);
2586
2587 /* Create a new message. */
2588 struct vhost_msg_node *vhost_new_msg(struct vhost_virtqueue *vq, int type)
2589 {
2590         /* Make sure all padding within the structure is initialized. */
2591         struct vhost_msg_node *node = kzalloc(sizeof(*node), GFP_KERNEL);
2592         if (!node)
2593                 return NULL;
2594
2595         node->vq = vq;
2596         node->msg.type = type;
2597         return node;
2598 }
2599 EXPORT_SYMBOL_GPL(vhost_new_msg);
2600
2601 void vhost_enqueue_msg(struct vhost_dev *dev, struct list_head *head,
2602                        struct vhost_msg_node *node)
2603 {
2604         spin_lock(&dev->iotlb_lock);
2605         list_add_tail(&node->node, head);
2606         spin_unlock(&dev->iotlb_lock);
2607
2608         wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
2609 }
2610 EXPORT_SYMBOL_GPL(vhost_enqueue_msg);
2611
2612 struct vhost_msg_node *vhost_dequeue_msg(struct vhost_dev *dev,
2613                                          struct list_head *head)
2614 {
2615         struct vhost_msg_node *node = NULL;
2616
2617         spin_lock(&dev->iotlb_lock);
2618         if (!list_empty(head)) {
2619                 node = list_first_entry(head, struct vhost_msg_node,
2620                                         node);
2621                 list_del(&node->node);
2622         }
2623         spin_unlock(&dev->iotlb_lock);
2624
2625         return node;
2626 }
2627 EXPORT_SYMBOL_GPL(vhost_dequeue_msg);
2628
2629 void vhost_set_backend_features(struct vhost_dev *dev, u64 features)
2630 {
2631         struct vhost_virtqueue *vq;
2632         int i;
2633
2634         mutex_lock(&dev->mutex);
2635         for (i = 0; i < dev->nvqs; ++i) {
2636                 vq = dev->vqs[i];
2637                 mutex_lock(&vq->mutex);
2638                 vq->acked_backend_features = features;
2639                 mutex_unlock(&vq->mutex);
2640         }
2641         mutex_unlock(&dev->mutex);
2642 }
2643 EXPORT_SYMBOL_GPL(vhost_set_backend_features);
2644
2645 static int __init vhost_init(void)
2646 {
2647         return 0;
2648 }
2649
2650 static void __exit vhost_exit(void)
2651 {
2652 }
2653
2654 module_init(vhost_init);
2655 module_exit(vhost_exit);
2656
2657 MODULE_VERSION("0.0.1");
2658 MODULE_LICENSE("GPL v2");
2659 MODULE_AUTHOR("Michael S. Tsirkin");
2660 MODULE_DESCRIPTION("Host kernel accelerator for virtio");