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_dev_flush(struct vhost_dev *dev)
 235 {
 236         struct vhost_flush_struct flush;
 237
 238         if (dev->worker) {
 239                 init_completion(&flush.wait_event);
 240                 vhost_work_init(&flush.work, vhost_flush_work);
 241
 242                 vhost_work_queue(dev, &flush.work);
 243                 wait_for_completion(&flush.wait_event);
 244         }
 245 }
 246 EXPORT_SYMBOL_GPL(vhost_dev_flush);
 247
 248 void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work)
 249 {
 250         if (!dev->worker)
 251                 return;
 252
 253         if (!test_and_set_bit(VHOST_WORK_QUEUED, &work->flags)) {
 254                 /* We can only add the work to the list after we're
 255                  * sure it was not in the list.
 256                  * test_and_set_bit() implies a memory barrier.
 257                  */
 258                 llist_add(&work->node, &dev->work_list);
 259                 wake_up_process(dev->worker);
 260         }
 261 }
 262 EXPORT_SYMBOL_GPL(vhost_work_queue);
 263
 264 /* A lockless hint for busy polling code to exit the loop */
 265 bool vhost_has_work(struct vhost_dev *dev)
 266 {
 267         return !llist_empty(&dev->work_list);
 268 }
 269 EXPORT_SYMBOL_GPL(vhost_has_work);
 270
 271 void vhost_poll_queue(struct vhost_poll *poll)
 272 {
 273         vhost_work_queue(poll->dev, &poll->work);
 274 }
 275 EXPORT_SYMBOL_GPL(vhost_poll_queue);
 276
 277 static void __vhost_vq_meta_reset(struct vhost_virtqueue *vq)
 278 {
 279         int j;
 280
 281         for (j = 0; j < VHOST_NUM_ADDRS; j++)
 282                 vq->meta_iotlb[j] = NULL;
 283 }
 284
 285 static void vhost_vq_meta_reset(struct vhost_dev *d)
 286 {
 287         int i;
 288
 289         for (i = 0; i < d->nvqs; ++i)
 290                 __vhost_vq_meta_reset(d->vqs[i]);
 291 }
 292
 293 static void vhost_vring_call_reset(struct vhost_vring_call *call_ctx)
 294 {
 295         call_ctx->ctx = NULL;
 296         memset(&call_ctx->producer, 0x0, sizeof(struct irq_bypass_producer));
 297 }
 298
 299 bool vhost_vq_is_setup(struct vhost_virtqueue *vq)
 300 {
 301         return vq->avail && vq->desc && vq->used && vhost_vq_access_ok(vq);
 302 }
 303 EXPORT_SYMBOL_GPL(vhost_vq_is_setup);
 304
 305 static void vhost_vq_reset(struct vhost_dev *dev,
 306                            struct vhost_virtqueue *vq)
 307 {
 308         vq->num = 1;
 309         vq->desc = NULL;
 310         vq->avail = NULL;
 311         vq->used = NULL;
 312         vq->last_avail_idx = 0;
 313         vq->avail_idx = 0;
 314         vq->last_used_idx = 0;
 315         vq->signalled_used = 0;
 316         vq->signalled_used_valid = false;
 317         vq->used_flags = 0;
 318         vq->log_used = false;
 319         vq->log_addr = -1ull;
 320         vq->private_data = NULL;
 321         vq->acked_features = 0;
 322         vq->acked_backend_features = 0;
 323         vq->log_base = NULL;
 324         vq->error_ctx = NULL;
 325         vq->kick = NULL;
 326         vq->log_ctx = NULL;
 327         vhost_disable_cross_endian(vq);
 328         vhost_reset_is_le(vq);
 329         vq->busyloop_timeout = 0;
 330         vq->umem = NULL;
 331         vq->iotlb = NULL;
 332         vhost_vring_call_reset(&vq->call_ctx);
 333         __vhost_vq_meta_reset(vq);
 334 }
 335
 336 static int vhost_worker(void *data)
 337 {
 338         struct vhost_dev *dev = data;
 339         struct vhost_work *work, *work_next;
 340         struct llist_node *node;
 341
 342         kthread_use_mm(dev->mm);
 343
 344         for (;;) {
 345                 /* mb paired w/ kthread_stop */
 346                 set_current_state(TASK_INTERRUPTIBLE);
 347
 348                 if (kthread_should_stop()) {
 349                         __set_current_state(TASK_RUNNING);
 350                         break;
 351                 }
 352
 353                 node = llist_del_all(&dev->work_list);
 354                 if (!node)
 355                         schedule();
 356
 357                 node = llist_reverse_order(node);
 358                 /* make sure flag is seen after deletion */
 359                 smp_wmb();
 360                 llist_for_each_entry_safe(work, work_next, node, node) {
 361                         clear_bit(VHOST_WORK_QUEUED, &work->flags);
 362                         __set_current_state(TASK_RUNNING);
 363                         kcov_remote_start_common(dev->kcov_handle);
 364                         work->fn(work);
 365                         kcov_remote_stop();
 366                         if (need_resched())
 367                                 schedule();
 368                 }
 369         }
 370         kthread_unuse_mm(dev->mm);
 371         return 0;
 372 }
 373
 374 static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq)
 375 {
 376         kfree(vq->indirect);
 377         vq->indirect = NULL;
 378         kfree(vq->log);
 379         vq->log = NULL;
 380         kfree(vq->heads);
 381         vq->heads = NULL;
 382 }
 383
 384 /* Helper to allocate iovec buffers for all vqs. */
 385 static long vhost_dev_alloc_iovecs(struct vhost_dev *dev)
 386 {
 387         struct vhost_virtqueue *vq;
 388         int i;
 389
 390         for (i = 0; i < dev->nvqs; ++i) {
 391                 vq = dev->vqs[i];
 392                 vq->indirect = kmalloc_array(UIO_MAXIOV,
 393                                              sizeof(*vq->indirect),
 394                                              GFP_KERNEL);
 395                 vq->log = kmalloc_array(dev->iov_limit, sizeof(*vq->log),
 396                                         GFP_KERNEL);
 397                 vq->heads = kmalloc_array(dev->iov_limit, sizeof(*vq->heads),
 398                                           GFP_KERNEL);
 399                 if (!vq->indirect || !vq->log || !vq->heads)
 400                         goto err_nomem;
 401         }
 402         return 0;
 403
 404 err_nomem:
 405         for (; i >= 0; --i)
 406                 vhost_vq_free_iovecs(dev->vqs[i]);
 407         return -ENOMEM;
 408 }
 409
 410 static void vhost_dev_free_iovecs(struct vhost_dev *dev)
 411 {
 412         int i;
 413
 414         for (i = 0; i < dev->nvqs; ++i)
 415                 vhost_vq_free_iovecs(dev->vqs[i]);
 416 }
 417
 418 bool vhost_exceeds_weight(struct vhost_virtqueue *vq,
 419                           int pkts, int total_len)
 420 {
 421         struct vhost_dev *dev = vq->dev;
 422
 423         if ((dev->byte_weight && total_len >= dev->byte_weight) ||
 424             pkts >= dev->weight) {
 425                 vhost_poll_queue(&vq->poll);
 426                 return true;
 427         }
 428
 429         return false;
 430 }
 431 EXPORT_SYMBOL_GPL(vhost_exceeds_weight);
 432
 433 static size_t vhost_get_avail_size(struct vhost_virtqueue *vq,
 434                                    unsigned int num)
 435 {
 436         size_t event __maybe_unused =
 437                vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
 438
 439         return sizeof(*vq->avail) +
 440                sizeof(*vq->avail->ring) * num + event;
 441 }
 442
 443 static size_t vhost_get_used_size(struct vhost_virtqueue *vq,
 444                                   unsigned int num)
 445 {
 446         size_t event __maybe_unused =
 447                vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
 448
 449         return sizeof(*vq->used) +
 450                sizeof(*vq->used->ring) * num + event;
 451 }
 452
 453 static size_t vhost_get_desc_size(struct vhost_virtqueue *vq,
 454                                   unsigned int num)
 455 {
 456         return sizeof(*vq->desc) * num;
 457 }
 458
 459 void vhost_dev_init(struct vhost_dev *dev,
 460                     struct vhost_virtqueue **vqs, int nvqs,
 461                     int iov_limit, int weight, int byte_weight,
 462                     bool use_worker,
 463                     int (*msg_handler)(struct vhost_dev *dev, u32 asid,
 464                                        struct vhost_iotlb_msg *msg))
 465 {
 466         struct vhost_virtqueue *vq;
 467         int i;
 468
 469         dev->vqs = vqs;
 470         dev->nvqs = nvqs;
 471         mutex_init(&dev->mutex);
 472         dev->log_ctx = NULL;
 473         dev->umem = NULL;
 474         dev->iotlb = NULL;
 475         dev->mm = NULL;
 476         dev->worker = NULL;
 477         dev->iov_limit = iov_limit;
 478         dev->weight = weight;
 479         dev->byte_weight = byte_weight;
 480         dev->use_worker = use_worker;
 481         dev->msg_handler = msg_handler;
 482         init_llist_head(&dev->work_list);
 483         init_waitqueue_head(&dev->wait);
 484         INIT_LIST_HEAD(&dev->read_list);
 485         INIT_LIST_HEAD(&dev->pending_list);
 486         spin_lock_init(&dev->iotlb_lock);
 487
 488
 489         for (i = 0; i < dev->nvqs; ++i) {
 490                 vq = dev->vqs[i];
 491                 vq->log = NULL;
 492                 vq->indirect = NULL;
 493                 vq->heads = NULL;
 494                 vq->dev = dev;
 495                 mutex_init(&vq->mutex);
 496                 vhost_vq_reset(dev, vq);
 497                 if (vq->handle_kick)
 498                         vhost_poll_init(&vq->poll, vq->handle_kick,
 499                                         EPOLLIN, dev);
 500         }
 501 }
 502 EXPORT_SYMBOL_GPL(vhost_dev_init);
 503
 504 /* Caller should have device mutex */
 505 long vhost_dev_check_owner(struct vhost_dev *dev)
 506 {
 507         /* Are you the owner? If not, I don't think you mean to do that */
 508         return dev->mm == current->mm ? 0 : -EPERM;
 509 }
 510 EXPORT_SYMBOL_GPL(vhost_dev_check_owner);
 511
 512 struct vhost_attach_cgroups_struct {
 513         struct vhost_work work;
 514         struct task_struct *owner;
 515         int ret;
 516 };
 517
 518 static void vhost_attach_cgroups_work(struct vhost_work *work)
 519 {
 520         struct vhost_attach_cgroups_struct *s;
 521
 522         s = container_of(work, struct vhost_attach_cgroups_struct, work);
 523         s->ret = cgroup_attach_task_all(s->owner, current);
 524 }
 525
 526 static int vhost_attach_cgroups(struct vhost_dev *dev)
 527 {
 528         struct vhost_attach_cgroups_struct attach;
 529
 530         attach.owner = current;
 531         vhost_work_init(&attach.work, vhost_attach_cgroups_work);
 532         vhost_work_queue(dev, &attach.work);
 533         vhost_dev_flush(dev);
 534         return attach.ret;
 535 }
 536
 537 /* Caller should have device mutex */
 538 bool vhost_dev_has_owner(struct vhost_dev *dev)
 539 {
 540         return dev->mm;
 541 }
 542 EXPORT_SYMBOL_GPL(vhost_dev_has_owner);
 543
 544 static void vhost_attach_mm(struct vhost_dev *dev)
 545 {
 546         /* No owner, become one */
 547         if (dev->use_worker) {
 548                 dev->mm = get_task_mm(current);
 549         } else {
 550                 /* vDPA device does not use worker thead, so there's
 551                  * no need to hold the address space for mm. This help
 552                  * to avoid deadlock in the case of mmap() which may
 553                  * held the refcnt of the file and depends on release
 554                  * method to remove vma.
 555                  */
 556                 dev->mm = current->mm;
 557                 mmgrab(dev->mm);
 558         }
 559 }
 560
 561 static void vhost_detach_mm(struct vhost_dev *dev)
 562 {
 563         if (!dev->mm)
 564                 return;
 565
 566         if (dev->use_worker)
 567                 mmput(dev->mm);
 568         else
 569                 mmdrop(dev->mm);
 570
 571         dev->mm = NULL;
 572 }
 573
 574 /* Caller should have device mutex */
 575 long vhost_dev_set_owner(struct vhost_dev *dev)
 576 {
 577         struct task_struct *worker;
 578         int err;
 579
 580         /* Is there an owner already? */
 581         if (vhost_dev_has_owner(dev)) {
 582                 err = -EBUSY;
 583                 goto err_mm;
 584         }
 585
 586         vhost_attach_mm(dev);
 587
 588         dev->kcov_handle = kcov_common_handle();
 589         if (dev->use_worker) {
 590                 worker = kthread_create(vhost_worker, dev,
 591                                         "vhost-%d", current->pid);
 592                 if (IS_ERR(worker)) {
 593                         err = PTR_ERR(worker);
 594                         goto err_worker;
 595                 }
 596
 597                 dev->worker = worker;
 598                 wake_up_process(worker); /* avoid contributing to loadavg */
 599
 600                 err = vhost_attach_cgroups(dev);
 601                 if (err)
 602                         goto err_cgroup;
 603         }
 604
 605         err = vhost_dev_alloc_iovecs(dev);
 606         if (err)
 607                 goto err_cgroup;
 608
 609         return 0;
 610 err_cgroup:
 611         if (dev->worker) {
 612                 kthread_stop(dev->worker);
 613                 dev->worker = NULL;
 614         }
 615 err_worker:
 616         vhost_detach_mm(dev);
 617         dev->kcov_handle = 0;
 618 err_mm:
 619         return err;
 620 }
 621 EXPORT_SYMBOL_GPL(vhost_dev_set_owner);
 622
 623 static struct vhost_iotlb *iotlb_alloc(void)
 624 {
 625         return vhost_iotlb_alloc(max_iotlb_entries,
 626                                  VHOST_IOTLB_FLAG_RETIRE);
 627 }
 628
 629 struct vhost_iotlb *vhost_dev_reset_owner_prepare(void)
 630 {
 631         return iotlb_alloc();
 632 }
 633 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner_prepare);
 634
 635 /* Caller should have device mutex */
 636 void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_iotlb *umem)
 637 {
 638         int i;
 639
 640         vhost_dev_cleanup(dev);
 641
 642         dev->umem = umem;
 643         /* We don't need VQ locks below since vhost_dev_cleanup makes sure
 644          * VQs aren't running.
 645          */
 646         for (i = 0; i < dev->nvqs; ++i)
 647                 dev->vqs[i]->umem = umem;
 648 }
 649 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner);
 650
 651 void vhost_dev_stop(struct vhost_dev *dev)
 652 {
 653         int i;
 654
 655         for (i = 0; i < dev->nvqs; ++i) {
 656                 if (dev->vqs[i]->kick && dev->vqs[i]->handle_kick)
 657                         vhost_poll_stop(&dev->vqs[i]->poll);
 658         }
 659
 660         vhost_dev_flush(dev);
 661 }
 662 EXPORT_SYMBOL_GPL(vhost_dev_stop);
 663
 664 void vhost_clear_msg(struct vhost_dev *dev)
 665 {
 666         struct vhost_msg_node *node, *n;
 667
 668         spin_lock(&dev->iotlb_lock);
 669
 670         list_for_each_entry_safe(node, n, &dev->read_list, node) {
 671                 list_del(&node->node);
 672                 kfree(node);
 673         }
 674
 675         list_for_each_entry_safe(node, n, &dev->pending_list, node) {
 676                 list_del(&node->node);
 677                 kfree(node);
 678         }
 679
 680         spin_unlock(&dev->iotlb_lock);
 681 }
 682 EXPORT_SYMBOL_GPL(vhost_clear_msg);
 683
 684 void vhost_dev_cleanup(struct vhost_dev *dev)
 685 {
 686         int i;
 687
 688         for (i = 0; i < dev->nvqs; ++i) {
 689                 if (dev->vqs[i]->error_ctx)
 690                         eventfd_ctx_put(dev->vqs[i]->error_ctx);
 691                 if (dev->vqs[i]->kick)
 692                         fput(dev->vqs[i]->kick);
 693                 if (dev->vqs[i]->call_ctx.ctx)
 694                         eventfd_ctx_put(dev->vqs[i]->call_ctx.ctx);
 695                 vhost_vq_reset(dev, dev->vqs[i]);
 696         }
 697         vhost_dev_free_iovecs(dev);
 698         if (dev->log_ctx)
 699                 eventfd_ctx_put(dev->log_ctx);
 700         dev->log_ctx = NULL;
 701         /* No one will access memory at this point */
 702         vhost_iotlb_free(dev->umem);
 703         dev->umem = NULL;
 704         vhost_iotlb_free(dev->iotlb);
 705         dev->iotlb = NULL;
 706         vhost_clear_msg(dev);
 707         wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
 708         WARN_ON(!llist_empty(&dev->work_list));
 709         if (dev->worker) {
 710                 kthread_stop(dev->worker);
 711                 dev->worker = NULL;
 712                 dev->kcov_handle = 0;
 713         }
 714         vhost_detach_mm(dev);
 715 }
 716 EXPORT_SYMBOL_GPL(vhost_dev_cleanup);
 717
 718 static bool log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
 719 {
 720         u64 a = addr / VHOST_PAGE_SIZE / 8;
 721
 722         /* Make sure 64 bit math will not overflow. */
 723         if (a > ULONG_MAX - (unsigned long)log_base ||
 724             a + (unsigned long)log_base > ULONG_MAX)
 725                 return false;
 726
 727         return access_ok(log_base + a,
 728                          (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8);
 729 }
 730
 731 /* Make sure 64 bit math will not overflow. */
 732 static bool vhost_overflow(u64 uaddr, u64 size)
 733 {
 734         if (uaddr > ULONG_MAX || size > ULONG_MAX)
 735                 return true;
 736
 737         if (!size)
 738                 return false;
 739
 740         return uaddr > ULONG_MAX - size + 1;
 741 }
 742
 743 /* Caller should have vq mutex and device mutex. */
 744 static bool vq_memory_access_ok(void __user *log_base, struct vhost_iotlb *umem,
 745                                 int log_all)
 746 {
 747         struct vhost_iotlb_map *map;
 748
 749         if (!umem)
 750                 return false;
 751
 752         list_for_each_entry(map, &umem->list, link) {
 753                 unsigned long a = map->addr;
 754
 755                 if (vhost_overflow(map->addr, map->size))
 756                         return false;
 757
 758
 759                 if (!access_ok((void __user *)a, map->size))
 760                         return false;
 761                 else if (log_all && !log_access_ok(log_base,
 762                                                    map->start,
 763                                                    map->size))
 764                         return false;
 765         }
 766         return true;
 767 }
 768
 769 static inline void __user *vhost_vq_meta_fetch(struct vhost_virtqueue *vq,
 770                                                u64 addr, unsigned int size,
 771                                                int type)
 772 {
 773         const struct vhost_iotlb_map *map = vq->meta_iotlb[type];
 774
 775         if (!map)
 776                 return NULL;
 777
 778         return (void __user *)(uintptr_t)(map->addr + addr - map->start);
 779 }
 780
 781 /* Can we switch to this memory table? */
 782 /* Caller should have device mutex but not vq mutex */
 783 static bool memory_access_ok(struct vhost_dev *d, struct vhost_iotlb *umem,
 784                              int log_all)
 785 {
 786         int i;
 787
 788         for (i = 0; i < d->nvqs; ++i) {
 789                 bool ok;
 790                 bool log;
 791
 792                 mutex_lock(&d->vqs[i]->mutex);
 793                 log = log_all || vhost_has_feature(d->vqs[i], VHOST_F_LOG_ALL);
 794                 /* If ring is inactive, will check when it's enabled. */
 795                 if (d->vqs[i]->private_data)
 796                         ok = vq_memory_access_ok(d->vqs[i]->log_base,
 797                                                  umem, log);
 798                 else
 799                         ok = true;
 800                 mutex_unlock(&d->vqs[i]->mutex);
 801                 if (!ok)
 802                         return false;
 803         }
 804         return true;
 805 }
 806
 807 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
 808                           struct iovec iov[], int iov_size, int access);
 809
 810 static int vhost_copy_to_user(struct vhost_virtqueue *vq, void __user *to,
 811                               const void *from, unsigned size)
 812 {
 813         int ret;
 814
 815         if (!vq->iotlb)
 816                 return __copy_to_user(to, from, size);
 817         else {
 818                 /* This function should be called after iotlb
 819                  * prefetch, which means we're sure that all vq
 820                  * could be access through iotlb. So -EAGAIN should
 821                  * not happen in this case.
 822                  */
 823                 struct iov_iter t;
 824                 void __user *uaddr = vhost_vq_meta_fetch(vq,
 825                                      (u64)(uintptr_t)to, size,
 826                                      VHOST_ADDR_USED);
 827
 828                 if (uaddr)
 829                         return __copy_to_user(uaddr, from, size);
 830
 831                 ret = translate_desc(vq, (u64)(uintptr_t)to, size, vq->iotlb_iov,
 832                                      ARRAY_SIZE(vq->iotlb_iov),
 833                                      VHOST_ACCESS_WO);
 834                 if (ret < 0)
 835                         goto out;
 836                 iov_iter_init(&t, ITER_DEST, vq->iotlb_iov, ret, size);
 837                 ret = copy_to_iter(from, size, &t);
 838                 if (ret == size)
 839                         ret = 0;
 840         }
 841 out:
 842         return ret;
 843 }
 844
 845 static int vhost_copy_from_user(struct vhost_virtqueue *vq, void *to,
 846                                 void __user *from, unsigned size)
 847 {
 848         int ret;
 849
 850         if (!vq->iotlb)
 851                 return __copy_from_user(to, from, size);
 852         else {
 853                 /* This function should be called after iotlb
 854                  * prefetch, which means we're sure that vq
 855                  * could be access through iotlb. So -EAGAIN should
 856                  * not happen in this case.
 857                  */
 858                 void __user *uaddr = vhost_vq_meta_fetch(vq,
 859                                      (u64)(uintptr_t)from, size,
 860                                      VHOST_ADDR_DESC);
 861                 struct iov_iter f;
 862
 863                 if (uaddr)
 864                         return __copy_from_user(to, uaddr, size);
 865
 866                 ret = translate_desc(vq, (u64)(uintptr_t)from, size, vq->iotlb_iov,
 867                                      ARRAY_SIZE(vq->iotlb_iov),
 868                                      VHOST_ACCESS_RO);
 869                 if (ret < 0) {
 870                         vq_err(vq, "IOTLB translation failure: uaddr "
 871                                "%p size 0x%llx\n", from,
 872                                (unsigned long long) size);
 873                         goto out;
 874                 }
 875                 iov_iter_init(&f, ITER_SOURCE, vq->iotlb_iov, ret, size);
 876                 ret = copy_from_iter(to, size, &f);
 877                 if (ret == size)
 878                         ret = 0;
 879         }
 880
 881 out:
 882         return ret;
 883 }
 884
 885 static void __user *__vhost_get_user_slow(struct vhost_virtqueue *vq,
 886                                           void __user *addr, unsigned int size,
 887                                           int type)
 888 {
 889         int ret;
 890
 891         ret = translate_desc(vq, (u64)(uintptr_t)addr, size, vq->iotlb_iov,
 892                              ARRAY_SIZE(vq->iotlb_iov),
 893                              VHOST_ACCESS_RO);
 894         if (ret < 0) {
 895                 vq_err(vq, "IOTLB translation failure: uaddr "
 896                         "%p size 0x%llx\n", addr,
 897                         (unsigned long long) size);
 898                 return NULL;
 899         }
 900
 901         if (ret != 1 || vq->iotlb_iov[0].iov_len != size) {
 902                 vq_err(vq, "Non atomic userspace memory access: uaddr "
 903                         "%p size 0x%llx\n", addr,
 904                         (unsigned long long) size);
 905                 return NULL;
 906         }
 907
 908         return vq->iotlb_iov[0].iov_base;
 909 }
 910
 911 /* This function should be called after iotlb
 912  * prefetch, which means we're sure that vq
 913  * could be access through iotlb. So -EAGAIN should
 914  * not happen in this case.
 915  */
 916 static inline void __user *__vhost_get_user(struct vhost_virtqueue *vq,
 917                                             void __user *addr, unsigned int size,
 918                                             int type)
 919 {
 920         void __user *uaddr = vhost_vq_meta_fetch(vq,
 921                              (u64)(uintptr_t)addr, size, type);
 922         if (uaddr)
 923                 return uaddr;
 924
 925         return __vhost_get_user_slow(vq, addr, size, type);
 926 }
 927
 928 #define vhost_put_user(vq, x, ptr)              \
 929 ({ \
 930         int ret; \
 931         if (!vq->iotlb) { \
 932                 ret = __put_user(x, ptr); \
 933         } else { \
 934                 __typeof__(ptr) to = \
 935                         (__typeof__(ptr)) __vhost_get_user(vq, ptr,     \
 936                                           sizeof(*ptr), VHOST_ADDR_USED); \
 937                 if (to != NULL) \
 938                         ret = __put_user(x, to); \
 939                 else \
 940                         ret = -EFAULT;  \
 941         } \
 942         ret; \
 943 })
 944
 945 static inline int vhost_put_avail_event(struct vhost_virtqueue *vq)
 946 {
 947         return vhost_put_user(vq, cpu_to_vhost16(vq, vq->avail_idx),
 948                               vhost_avail_event(vq));
 949 }
 950
 951 static inline int vhost_put_used(struct vhost_virtqueue *vq,
 952                                  struct vring_used_elem *head, int idx,
 953                                  int count)
 954 {
 955         return vhost_copy_to_user(vq, vq->used->ring + idx, head,
 956                                   count * sizeof(*head));
 957 }
 958
 959 static inline int vhost_put_used_flags(struct vhost_virtqueue *vq)
 960
 961 {
 962         return vhost_put_user(vq, cpu_to_vhost16(vq, vq->used_flags),
 963                               &vq->used->flags);
 964 }
 965
 966 static inline int vhost_put_used_idx(struct vhost_virtqueue *vq)
 967
 968 {
 969         return vhost_put_user(vq, cpu_to_vhost16(vq, vq->last_used_idx),
 970                               &vq->used->idx);
 971 }
 972
 973 #define vhost_get_user(vq, x, ptr, type)                \
 974 ({ \
 975         int ret; \
 976         if (!vq->iotlb) { \
 977                 ret = __get_user(x, ptr); \
 978         } else { \
 979                 __typeof__(ptr) from = \
 980                         (__typeof__(ptr)) __vhost_get_user(vq, ptr, \
 981                                                            sizeof(*ptr), \
 982                                                            type); \
 983                 if (from != NULL) \
 984                         ret = __get_user(x, from); \
 985                 else \
 986                         ret = -EFAULT; \
 987         } \
 988         ret; \
 989 })
 990
 991 #define vhost_get_avail(vq, x, ptr) \
 992         vhost_get_user(vq, x, ptr, VHOST_ADDR_AVAIL)
 993
 994 #define vhost_get_used(vq, x, ptr) \
 995         vhost_get_user(vq, x, ptr, VHOST_ADDR_USED)
 996
 997 static void vhost_dev_lock_vqs(struct vhost_dev *d)
 998 {
 999         int i = 0;
1000         for (i = 0; i < d->nvqs; ++i)
1001                 mutex_lock_nested(&d->vqs[i]->mutex, i);
1002 }
1003
1004 static void vhost_dev_unlock_vqs(struct vhost_dev *d)
1005 {
1006         int i = 0;
1007         for (i = 0; i < d->nvqs; ++i)
1008                 mutex_unlock(&d->vqs[i]->mutex);
1009 }
1010
1011 static inline int vhost_get_avail_idx(struct vhost_virtqueue *vq,
1012                                       __virtio16 *idx)
1013 {
1014         return vhost_get_avail(vq, *idx, &vq->avail->idx);
1015 }
1016
1017 static inline int vhost_get_avail_head(struct vhost_virtqueue *vq,
1018                                        __virtio16 *head, int idx)
1019 {
1020         return vhost_get_avail(vq, *head,
1021                                &vq->avail->ring[idx & (vq->num - 1)]);
1022 }
1023
1024 static inline int vhost_get_avail_flags(struct vhost_virtqueue *vq,
1025                                         __virtio16 *flags)
1026 {
1027         return vhost_get_avail(vq, *flags, &vq->avail->flags);
1028 }
1029
1030 static inline int vhost_get_used_event(struct vhost_virtqueue *vq,
1031                                        __virtio16 *event)
1032 {
1033         return vhost_get_avail(vq, *event, vhost_used_event(vq));
1034 }
1035
1036 static inline int vhost_get_used_idx(struct vhost_virtqueue *vq,
1037                                      __virtio16 *idx)
1038 {
1039         return vhost_get_used(vq, *idx, &vq->used->idx);
1040 }
1041
1042 static inline int vhost_get_desc(struct vhost_virtqueue *vq,
1043                                  struct vring_desc *desc, int idx)
1044 {
1045         return vhost_copy_from_user(vq, desc, vq->desc + idx, sizeof(*desc));
1046 }
1047
1048 static void vhost_iotlb_notify_vq(struct vhost_dev *d,
1049                                   struct vhost_iotlb_msg *msg)
1050 {
1051         struct vhost_msg_node *node, *n;
1052
1053         spin_lock(&d->iotlb_lock);
1054
1055         list_for_each_entry_safe(node, n, &d->pending_list, node) {
1056                 struct vhost_iotlb_msg *vq_msg = &node->msg.iotlb;
1057                 if (msg->iova <= vq_msg->iova &&
1058                     msg->iova + msg->size - 1 >= vq_msg->iova &&
1059                     vq_msg->type == VHOST_IOTLB_MISS) {
1060                         vhost_poll_queue(&node->vq->poll);
1061                         list_del(&node->node);
1062                         kfree(node);
1063                 }
1064         }
1065
1066         spin_unlock(&d->iotlb_lock);
1067 }
1068
1069 static bool umem_access_ok(u64 uaddr, u64 size, int access)
1070 {
1071         unsigned long a = uaddr;
1072
1073         /* Make sure 64 bit math will not overflow. */
1074         if (vhost_overflow(uaddr, size))
1075                 return false;
1076
1077         if ((access & VHOST_ACCESS_RO) &&
1078             !access_ok((void __user *)a, size))
1079                 return false;
1080         if ((access & VHOST_ACCESS_WO) &&
1081             !access_ok((void __user *)a, size))
1082                 return false;
1083         return true;
1084 }
1085
1086 static int vhost_process_iotlb_msg(struct vhost_dev *dev, u32 asid,
1087                                    struct vhost_iotlb_msg *msg)
1088 {
1089         int ret = 0;
1090
1091         if (asid != 0)
1092                 return -EINVAL;
1093
1094         mutex_lock(&dev->mutex);
1095         vhost_dev_lock_vqs(dev);
1096         switch (msg->type) {
1097         case VHOST_IOTLB_UPDATE:
1098                 if (!dev->iotlb) {
1099                         ret = -EFAULT;
1100                         break;
1101                 }
1102                 if (!umem_access_ok(msg->uaddr, msg->size, msg->perm)) {
1103                         ret = -EFAULT;
1104                         break;
1105                 }
1106                 vhost_vq_meta_reset(dev);
1107                 if (vhost_iotlb_add_range(dev->iotlb, msg->iova,
1108                                           msg->iova + msg->size - 1,
1109                                           msg->uaddr, msg->perm)) {
1110                         ret = -ENOMEM;
1111                         break;
1112                 }
1113                 vhost_iotlb_notify_vq(dev, msg);
1114                 break;
1115         case VHOST_IOTLB_INVALIDATE:
1116                 if (!dev->iotlb) {
1117                         ret = -EFAULT;
1118                         break;
1119                 }
1120                 vhost_vq_meta_reset(dev);
1121                 vhost_iotlb_del_range(dev->iotlb, msg->iova,
1122                                       msg->iova + msg->size - 1);
1123                 break;
1124         default:
1125                 ret = -EINVAL;
1126                 break;
1127         }
1128
1129         vhost_dev_unlock_vqs(dev);
1130         mutex_unlock(&dev->mutex);
1131
1132         return ret;
1133 }
1134 ssize_t vhost_chr_write_iter(struct vhost_dev *dev,
1135                              struct iov_iter *from)
1136 {
1137         struct vhost_iotlb_msg msg;
1138         size_t offset;
1139         int type, ret;
1140         u32 asid = 0;
1141
1142         ret = copy_from_iter(&type, sizeof(type), from);
1143         if (ret != sizeof(type)) {
1144                 ret = -EINVAL;
1145                 goto done;
1146         }
1147
1148         switch (type) {
1149         case VHOST_IOTLB_MSG:
1150                 /* There maybe a hole after type for V1 message type,
1151                  * so skip it here.
1152                  */
1153                 offset = offsetof(struct vhost_msg, iotlb) - sizeof(int);
1154                 break;
1155         case VHOST_IOTLB_MSG_V2:
1156                 if (vhost_backend_has_feature(dev->vqs[0],
1157                                               VHOST_BACKEND_F_IOTLB_ASID)) {
1158                         ret = copy_from_iter(&asid, sizeof(asid), from);
1159                         if (ret != sizeof(asid)) {
1160                                 ret = -EINVAL;
1161                                 goto done;
1162                         }
1163                         offset = 0;
1164                 } else
1165                         offset = sizeof(__u32);
1166                 break;
1167         default:
1168                 ret = -EINVAL;
1169                 goto done;
1170         }
1171
1172         iov_iter_advance(from, offset);
1173         ret = copy_from_iter(&msg, sizeof(msg), from);
1174         if (ret != sizeof(msg)) {
1175                 ret = -EINVAL;
1176                 goto done;
1177         }
1178
1179         if ((msg.type == VHOST_IOTLB_UPDATE ||
1180              msg.type == VHOST_IOTLB_INVALIDATE) &&
1181              msg.size == 0) {
1182                 ret = -EINVAL;
1183                 goto done;
1184         }
1185
1186         if (dev->msg_handler)
1187                 ret = dev->msg_handler(dev, asid, &msg);
1188         else
1189                 ret = vhost_process_iotlb_msg(dev, asid, &msg);
1190         if (ret) {
1191                 ret = -EFAULT;
1192                 goto done;
1193         }
1194
1195         ret = (type == VHOST_IOTLB_MSG) ? sizeof(struct vhost_msg) :
1196               sizeof(struct vhost_msg_v2);
1197 done:
1198         return ret;
1199 }
1200 EXPORT_SYMBOL(vhost_chr_write_iter);
1201
1202 __poll_t vhost_chr_poll(struct file *file, struct vhost_dev *dev,
1203                             poll_table *wait)
1204 {
1205         __poll_t mask = 0;
1206
1207         poll_wait(file, &dev->wait, wait);
1208
1209         if (!list_empty(&dev->read_list))
1210                 mask |= EPOLLIN | EPOLLRDNORM;
1211
1212         return mask;
1213 }
1214 EXPORT_SYMBOL(vhost_chr_poll);
1215
1216 ssize_t vhost_chr_read_iter(struct vhost_dev *dev, struct iov_iter *to,
1217                             int noblock)
1218 {
1219         DEFINE_WAIT(wait);
1220         struct vhost_msg_node *node;
1221         ssize_t ret = 0;
1222         unsigned size = sizeof(struct vhost_msg);
1223
1224         if (iov_iter_count(to) < size)
1225                 return 0;
1226
1227         while (1) {
1228                 if (!noblock)
1229                         prepare_to_wait(&dev->wait, &wait,
1230                                         TASK_INTERRUPTIBLE);
1231
1232                 node = vhost_dequeue_msg(dev, &dev->read_list);
1233                 if (node)
1234                         break;
1235                 if (noblock) {
1236                         ret = -EAGAIN;
1237                         break;
1238                 }
1239                 if (signal_pending(current)) {
1240                         ret = -ERESTARTSYS;
1241                         break;
1242                 }
1243                 if (!dev->iotlb) {
1244                         ret = -EBADFD;
1245                         break;
1246                 }
1247
1248                 schedule();
1249         }
1250
1251         if (!noblock)
1252                 finish_wait(&dev->wait, &wait);
1253
1254         if (node) {
1255                 struct vhost_iotlb_msg *msg;
1256                 void *start = &node->msg;
1257
1258                 switch (node->msg.type) {
1259                 case VHOST_IOTLB_MSG:
1260                         size = sizeof(node->msg);
1261                         msg = &node->msg.iotlb;
1262                         break;
1263                 case VHOST_IOTLB_MSG_V2:
1264                         size = sizeof(node->msg_v2);
1265                         msg = &node->msg_v2.iotlb;
1266                         break;
1267                 default:
1268                         BUG();
1269                         break;
1270                 }
1271
1272                 ret = copy_to_iter(start, size, to);
1273                 if (ret != size || msg->type != VHOST_IOTLB_MISS) {
1274                         kfree(node);
1275                         return ret;
1276                 }
1277                 vhost_enqueue_msg(dev, &dev->pending_list, node);
1278         }
1279
1280         return ret;
1281 }
1282 EXPORT_SYMBOL_GPL(vhost_chr_read_iter);
1283
1284 static int vhost_iotlb_miss(struct vhost_virtqueue *vq, u64 iova, int access)
1285 {
1286         struct vhost_dev *dev = vq->dev;
1287         struct vhost_msg_node *node;
1288         struct vhost_iotlb_msg *msg;
1289         bool v2 = vhost_backend_has_feature(vq, VHOST_BACKEND_F_IOTLB_MSG_V2);
1290
1291         node = vhost_new_msg(vq, v2 ? VHOST_IOTLB_MSG_V2 : VHOST_IOTLB_MSG);
1292         if (!node)
1293                 return -ENOMEM;
1294
1295         if (v2) {
1296                 node->msg_v2.type = VHOST_IOTLB_MSG_V2;
1297                 msg = &node->msg_v2.iotlb;
1298         } else {
1299                 msg = &node->msg.iotlb;
1300         }
1301
1302         msg->type = VHOST_IOTLB_MISS;
1303         msg->iova = iova;
1304         msg->perm = access;
1305
1306         vhost_enqueue_msg(dev, &dev->read_list, node);
1307
1308         return 0;
1309 }
1310
1311 static bool vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
1312                          vring_desc_t __user *desc,
1313                          vring_avail_t __user *avail,
1314                          vring_used_t __user *used)
1315
1316 {
1317         /* If an IOTLB device is present, the vring addresses are
1318          * GIOVAs. Access validation occurs at prefetch time. */
1319         if (vq->iotlb)
1320                 return true;
1321
1322         return access_ok(desc, vhost_get_desc_size(vq, num)) &&
1323                access_ok(avail, vhost_get_avail_size(vq, num)) &&
1324                access_ok(used, vhost_get_used_size(vq, num));
1325 }
1326
1327 static void vhost_vq_meta_update(struct vhost_virtqueue *vq,
1328                                  const struct vhost_iotlb_map *map,
1329                                  int type)
1330 {
1331         int access = (type == VHOST_ADDR_USED) ?
1332                      VHOST_ACCESS_WO : VHOST_ACCESS_RO;
1333
1334         if (likely(map->perm & access))
1335                 vq->meta_iotlb[type] = map;
1336 }
1337
1338 static bool iotlb_access_ok(struct vhost_virtqueue *vq,
1339                             int access, u64 addr, u64 len, int type)
1340 {
1341         const struct vhost_iotlb_map *map;
1342         struct vhost_iotlb *umem = vq->iotlb;
1343         u64 s = 0, size, orig_addr = addr, last = addr + len - 1;
1344
1345         if (vhost_vq_meta_fetch(vq, addr, len, type))
1346                 return true;
1347
1348         while (len > s) {
1349                 map = vhost_iotlb_itree_first(umem, addr, last);
1350                 if (map == NULL || map->start > addr) {
1351                         vhost_iotlb_miss(vq, addr, access);
1352                         return false;
1353                 } else if (!(map->perm & access)) {
1354                         /* Report the possible access violation by
1355                          * request another translation from userspace.
1356                          */
1357                         return false;
1358                 }
1359
1360                 size = map->size - addr + map->start;
1361
1362                 if (orig_addr == addr && size >= len)
1363                         vhost_vq_meta_update(vq, map, type);
1364
1365                 s += size;
1366                 addr += size;
1367         }
1368
1369         return true;
1370 }
1371
1372 int vq_meta_prefetch(struct vhost_virtqueue *vq)
1373 {
1374         unsigned int num = vq->num;
1375
1376         if (!vq->iotlb)
1377                 return 1;
1378
1379         return iotlb_access_ok(vq, VHOST_MAP_RO, (u64)(uintptr_t)vq->desc,
1380                                vhost_get_desc_size(vq, num), VHOST_ADDR_DESC) &&
1381                iotlb_access_ok(vq, VHOST_MAP_RO, (u64)(uintptr_t)vq->avail,
1382                                vhost_get_avail_size(vq, num),
1383                                VHOST_ADDR_AVAIL) &&
1384                iotlb_access_ok(vq, VHOST_MAP_WO, (u64)(uintptr_t)vq->used,
1385                                vhost_get_used_size(vq, num), VHOST_ADDR_USED);
1386 }
1387 EXPORT_SYMBOL_GPL(vq_meta_prefetch);
1388
1389 /* Can we log writes? */
1390 /* Caller should have device mutex but not vq mutex */
1391 bool vhost_log_access_ok(struct vhost_dev *dev)
1392 {
1393         return memory_access_ok(dev, dev->umem, 1);
1394 }
1395 EXPORT_SYMBOL_GPL(vhost_log_access_ok);
1396
1397 static bool vq_log_used_access_ok(struct vhost_virtqueue *vq,
1398                                   void __user *log_base,
1399                                   bool log_used,
1400                                   u64 log_addr)
1401 {
1402         /* If an IOTLB device is present, log_addr is a GIOVA that
1403          * will never be logged by log_used(). */
1404         if (vq->iotlb)
1405                 return true;
1406
1407         return !log_used || log_access_ok(log_base, log_addr,
1408                                           vhost_get_used_size(vq, vq->num));
1409 }
1410
1411 /* Verify access for write logging. */
1412 /* Caller should have vq mutex and device mutex */
1413 static bool vq_log_access_ok(struct vhost_virtqueue *vq,
1414                              void __user *log_base)
1415 {
1416         return vq_memory_access_ok(log_base, vq->umem,
1417                                    vhost_has_feature(vq, VHOST_F_LOG_ALL)) &&
1418                 vq_log_used_access_ok(vq, log_base, vq->log_used, vq->log_addr);
1419 }
1420
1421 /* Can we start vq? */
1422 /* Caller should have vq mutex and device mutex */
1423 bool vhost_vq_access_ok(struct vhost_virtqueue *vq)
1424 {
1425         if (!vq_log_access_ok(vq, vq->log_base))
1426                 return false;
1427
1428         return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used);
1429 }
1430 EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
1431
1432 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
1433 {
1434         struct vhost_memory mem, *newmem;
1435         struct vhost_memory_region *region;
1436         struct vhost_iotlb *newumem, *oldumem;
1437         unsigned long size = offsetof(struct vhost_memory, regions);
1438         int i;
1439
1440         if (copy_from_user(&mem, m, size))
1441                 return -EFAULT;
1442         if (mem.padding)
1443                 return -EOPNOTSUPP;
1444         if (mem.nregions > max_mem_regions)
1445                 return -E2BIG;
1446         newmem = kvzalloc(struct_size(newmem, regions, mem.nregions),
1447                         GFP_KERNEL);
1448         if (!newmem)
1449                 return -ENOMEM;
1450
1451         memcpy(newmem, &mem, size);
1452         if (copy_from_user(newmem->regions, m->regions,
1453                            flex_array_size(newmem, regions, mem.nregions))) {
1454                 kvfree(newmem);
1455                 return -EFAULT;
1456         }
1457
1458         newumem = iotlb_alloc();
1459         if (!newumem) {
1460                 kvfree(newmem);
1461                 return -ENOMEM;
1462         }
1463
1464         for (region = newmem->regions;
1465              region < newmem->regions + mem.nregions;
1466              region++) {
1467                 if (vhost_iotlb_add_range(newumem,
1468                                           region->guest_phys_addr,
1469                                           region->guest_phys_addr +
1470                                           region->memory_size - 1,
1471                                           region->userspace_addr,
1472                                           VHOST_MAP_RW))
1473                         goto err;
1474         }
1475
1476         if (!memory_access_ok(d, newumem, 0))
1477                 goto err;
1478
1479         oldumem = d->umem;
1480         d->umem = newumem;
1481
1482         /* All memory accesses are done under some VQ mutex. */
1483         for (i = 0; i < d->nvqs; ++i) {
1484                 mutex_lock(&d->vqs[i]->mutex);
1485                 d->vqs[i]->umem = newumem;
1486                 mutex_unlock(&d->vqs[i]->mutex);
1487         }
1488
1489         kvfree(newmem);
1490         vhost_iotlb_free(oldumem);
1491         return 0;
1492
1493 err:
1494         vhost_iotlb_free(newumem);
1495         kvfree(newmem);
1496         return -EFAULT;
1497 }
1498
1499 static long vhost_vring_set_num(struct vhost_dev *d,
1500                                 struct vhost_virtqueue *vq,
1501                                 void __user *argp)
1502 {
1503         struct vhost_vring_state s;
1504
1505         /* Resizing ring with an active backend?
1506          * You don't want to do that. */
1507         if (vq->private_data)
1508                 return -EBUSY;
1509
1510         if (copy_from_user(&s, argp, sizeof s))
1511                 return -EFAULT;
1512
1513         if (!s.num || s.num > 0xffff || (s.num & (s.num - 1)))
1514                 return -EINVAL;
1515         vq->num = s.num;
1516
1517         return 0;
1518 }
1519
1520 static long vhost_vring_set_addr(struct vhost_dev *d,
1521                                  struct vhost_virtqueue *vq,
1522                                  void __user *argp)
1523 {
1524         struct vhost_vring_addr a;
1525
1526         if (copy_from_user(&a, argp, sizeof a))
1527                 return -EFAULT;
1528         if (a.flags & ~(0x1 << VHOST_VRING_F_LOG))
1529                 return -EOPNOTSUPP;
1530
1531         /* For 32bit, verify that the top 32bits of the user
1532            data are set to zero. */
1533         if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr ||
1534             (u64)(unsigned long)a.used_user_addr != a.used_user_addr ||
1535             (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr)
1536                 return -EFAULT;
1537
1538         /* Make sure it's safe to cast pointers to vring types. */
1539         BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE);
1540         BUILD_BUG_ON(__alignof__ *vq->used > VRING_USED_ALIGN_SIZE);
1541         if ((a.avail_user_addr & (VRING_AVAIL_ALIGN_SIZE - 1)) ||
1542             (a.used_user_addr & (VRING_USED_ALIGN_SIZE - 1)) ||
1543             (a.log_guest_addr & (VRING_USED_ALIGN_SIZE - 1)))
1544                 return -EINVAL;
1545
1546         /* We only verify access here if backend is configured.
1547          * If it is not, we don't as size might not have been setup.
1548          * We will verify when backend is configured. */
1549         if (vq->private_data) {
1550                 if (!vq_access_ok(vq, vq->num,
1551                         (void __user *)(unsigned long)a.desc_user_addr,
1552                         (void __user *)(unsigned long)a.avail_user_addr,
1553                         (void __user *)(unsigned long)a.used_user_addr))
1554                         return -EINVAL;
1555
1556                 /* Also validate log access for used ring if enabled. */
1557                 if (!vq_log_used_access_ok(vq, vq->log_base,
1558                                 a.flags & (0x1 << VHOST_VRING_F_LOG),
1559                                 a.log_guest_addr))
1560                         return -EINVAL;
1561         }
1562
1563         vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
1564         vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
1565         vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
1566         vq->log_addr = a.log_guest_addr;
1567         vq->used = (void __user *)(unsigned long)a.used_user_addr;
1568
1569         return 0;
1570 }
1571
1572 static long vhost_vring_set_num_addr(struct vhost_dev *d,
1573                                      struct vhost_virtqueue *vq,
1574                                      unsigned int ioctl,
1575                                      void __user *argp)
1576 {
1577         long r;
1578
1579         mutex_lock(&vq->mutex);
1580
1581         switch (ioctl) {
1582         case VHOST_SET_VRING_NUM:
1583                 r = vhost_vring_set_num(d, vq, argp);
1584                 break;
1585         case VHOST_SET_VRING_ADDR:
1586                 r = vhost_vring_set_addr(d, vq, argp);
1587                 break;
1588         default:
1589                 BUG();
1590         }
1591
1592         mutex_unlock(&vq->mutex);
1593
1594         return r;
1595 }
1596 long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
1597 {
1598         struct file *eventfp, *filep = NULL;
1599         bool pollstart = false, pollstop = false;
1600         struct eventfd_ctx *ctx = NULL;
1601         u32 __user *idxp = argp;
1602         struct vhost_virtqueue *vq;
1603         struct vhost_vring_state s;
1604         struct vhost_vring_file f;
1605         u32 idx;
1606         long r;
1607
1608         r = get_user(idx, idxp);
1609         if (r < 0)
1610                 return r;
1611         if (idx >= d->nvqs)
1612                 return -ENOBUFS;
1613
1614         idx = array_index_nospec(idx, d->nvqs);
1615         vq = d->vqs[idx];
1616
1617         if (ioctl == VHOST_SET_VRING_NUM ||
1618             ioctl == VHOST_SET_VRING_ADDR) {
1619                 return vhost_vring_set_num_addr(d, vq, ioctl, argp);
1620         }
1621
1622         mutex_lock(&vq->mutex);
1623
1624         switch (ioctl) {
1625         case VHOST_SET_VRING_BASE:
1626                 /* Moving base with an active backend?
1627                  * You don't want to do that. */
1628                 if (vq->private_data) {
1629                         r = -EBUSY;
1630                         break;
1631                 }
1632                 if (copy_from_user(&s, argp, sizeof s)) {
1633                         r = -EFAULT;
1634                         break;
1635                 }
1636                 if (s.num > 0xffff) {
1637                         r = -EINVAL;
1638                         break;
1639                 }
1640                 vq->last_avail_idx = s.num;
1641                 /* Forget the cached index value. */
1642                 vq->avail_idx = vq->last_avail_idx;
1643                 break;
1644         case VHOST_GET_VRING_BASE:
1645                 s.index = idx;
1646                 s.num = vq->last_avail_idx;
1647                 if (copy_to_user(argp, &s, sizeof s))
1648                         r = -EFAULT;
1649                 break;
1650         case VHOST_SET_VRING_KICK:
1651                 if (copy_from_user(&f, argp, sizeof f)) {
1652                         r = -EFAULT;
1653                         break;
1654                 }
1655                 eventfp = f.fd == VHOST_FILE_UNBIND ? NULL : eventfd_fget(f.fd);
1656                 if (IS_ERR(eventfp)) {
1657                         r = PTR_ERR(eventfp);
1658                         break;
1659                 }
1660                 if (eventfp != vq->kick) {
1661                         pollstop = (filep = vq->kick) != NULL;
1662                         pollstart = (vq->kick = eventfp) != NULL;
1663                 } else
1664                         filep = eventfp;
1665                 break;
1666         case VHOST_SET_VRING_CALL:
1667                 if (copy_from_user(&f, argp, sizeof f)) {
1668                         r = -EFAULT;
1669                         break;
1670                 }
1671                 ctx = f.fd == VHOST_FILE_UNBIND ? NULL : eventfd_ctx_fdget(f.fd);
1672                 if (IS_ERR(ctx)) {
1673                         r = PTR_ERR(ctx);
1674                         break;
1675                 }
1676
1677                 swap(ctx, vq->call_ctx.ctx);
1678                 break;
1679         case VHOST_SET_VRING_ERR:
1680                 if (copy_from_user(&f, argp, sizeof f)) {
1681                         r = -EFAULT;
1682                         break;
1683                 }
1684                 ctx = f.fd == VHOST_FILE_UNBIND ? NULL : eventfd_ctx_fdget(f.fd);
1685                 if (IS_ERR(ctx)) {
1686                         r = PTR_ERR(ctx);
1687                         break;
1688                 }
1689                 swap(ctx, vq->error_ctx);
1690                 break;
1691         case VHOST_SET_VRING_ENDIAN:
1692                 r = vhost_set_vring_endian(vq, argp);
1693                 break;
1694         case VHOST_GET_VRING_ENDIAN:
1695                 r = vhost_get_vring_endian(vq, idx, argp);
1696                 break;
1697         case VHOST_SET_VRING_BUSYLOOP_TIMEOUT:
1698                 if (copy_from_user(&s, argp, sizeof(s))) {
1699                         r = -EFAULT;
1700                         break;
1701                 }
1702                 vq->busyloop_timeout = s.num;
1703                 break;
1704         case VHOST_GET_VRING_BUSYLOOP_TIMEOUT:
1705                 s.index = idx;
1706                 s.num = vq->busyloop_timeout;
1707                 if (copy_to_user(argp, &s, sizeof(s)))
1708                         r = -EFAULT;
1709                 break;
1710         default:
1711                 r = -ENOIOCTLCMD;
1712         }
1713
1714         if (pollstop && vq->handle_kick)
1715                 vhost_poll_stop(&vq->poll);
1716
1717         if (!IS_ERR_OR_NULL(ctx))
1718                 eventfd_ctx_put(ctx);
1719         if (filep)
1720                 fput(filep);
1721
1722         if (pollstart && vq->handle_kick)
1723                 r = vhost_poll_start(&vq->poll, vq->kick);
1724
1725         mutex_unlock(&vq->mutex);
1726
1727         if (pollstop && vq->handle_kick)
1728                 vhost_dev_flush(vq->poll.dev);
1729         return r;
1730 }
1731 EXPORT_SYMBOL_GPL(vhost_vring_ioctl);
1732
1733 int vhost_init_device_iotlb(struct vhost_dev *d)
1734 {
1735         struct vhost_iotlb *niotlb, *oiotlb;
1736         int i;
1737
1738         niotlb = iotlb_alloc();
1739         if (!niotlb)
1740                 return -ENOMEM;
1741
1742         oiotlb = d->iotlb;
1743         d->iotlb = niotlb;
1744
1745         for (i = 0; i < d->nvqs; ++i) {
1746                 struct vhost_virtqueue *vq = d->vqs[i];
1747
1748                 mutex_lock(&vq->mutex);
1749                 vq->iotlb = niotlb;
1750                 __vhost_vq_meta_reset(vq);
1751                 mutex_unlock(&vq->mutex);
1752         }
1753
1754         vhost_iotlb_free(oiotlb);
1755
1756         return 0;
1757 }
1758 EXPORT_SYMBOL_GPL(vhost_init_device_iotlb);
1759
1760 /* Caller must have device mutex */
1761 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
1762 {
1763         struct eventfd_ctx *ctx;
1764         u64 p;
1765         long r;
1766         int i, fd;
1767
1768         /* If you are not the owner, you can become one */
1769         if (ioctl == VHOST_SET_OWNER) {
1770                 r = vhost_dev_set_owner(d);
1771                 goto done;
1772         }
1773
1774         /* You must be the owner to do anything else */
1775         r = vhost_dev_check_owner(d);
1776         if (r)
1777                 goto done;
1778
1779         switch (ioctl) {
1780         case VHOST_SET_MEM_TABLE:
1781                 r = vhost_set_memory(d, argp);
1782                 break;
1783         case VHOST_SET_LOG_BASE:
1784                 if (copy_from_user(&p, argp, sizeof p)) {
1785                         r = -EFAULT;
1786                         break;
1787                 }
1788                 if ((u64)(unsigned long)p != p) {
1789                         r = -EFAULT;
1790                         break;
1791                 }
1792                 for (i = 0; i < d->nvqs; ++i) {
1793                         struct vhost_virtqueue *vq;
1794                         void __user *base = (void __user *)(unsigned long)p;
1795                         vq = d->vqs[i];
1796                         mutex_lock(&vq->mutex);
1797                         /* If ring is inactive, will check when it's enabled. */
1798                         if (vq->private_data && !vq_log_access_ok(vq, base))
1799                                 r = -EFAULT;
1800                         else
1801                                 vq->log_base = base;
1802                         mutex_unlock(&vq->mutex);
1803                 }
1804                 break;
1805         case VHOST_SET_LOG_FD:
1806                 r = get_user(fd, (int __user *)argp);
1807                 if (r < 0)
1808                         break;
1809                 ctx = fd == VHOST_FILE_UNBIND ? NULL : eventfd_ctx_fdget(fd);
1810                 if (IS_ERR(ctx)) {
1811                         r = PTR_ERR(ctx);
1812                         break;
1813                 }
1814                 swap(ctx, d->log_ctx);
1815                 for (i = 0; i < d->nvqs; ++i) {
1816                         mutex_lock(&d->vqs[i]->mutex);
1817                         d->vqs[i]->log_ctx = d->log_ctx;
1818                         mutex_unlock(&d->vqs[i]->mutex);
1819                 }
1820                 if (ctx)
1821                         eventfd_ctx_put(ctx);
1822                 break;
1823         default:
1824                 r = -ENOIOCTLCMD;
1825                 break;
1826         }
1827 done:
1828         return r;
1829 }
1830 EXPORT_SYMBOL_GPL(vhost_dev_ioctl);
1831
1832 /* TODO: This is really inefficient.  We need something like get_user()
1833  * (instruction directly accesses the data, with an exception table entry
1834  * returning -EFAULT). See Documentation/x86/exception-tables.rst.
1835  */
1836 static int set_bit_to_user(int nr, void __user *addr)
1837 {
1838         unsigned long log = (unsigned long)addr;
1839         struct page *page;
1840         void *base;
1841         int bit = nr + (log % PAGE_SIZE) * 8;
1842         int r;
1843
1844         r = pin_user_pages_fast(log, 1, FOLL_WRITE, &page);
1845         if (r < 0)
1846                 return r;
1847         BUG_ON(r != 1);
1848         base = kmap_atomic(page);
1849         set_bit(bit, base);
1850         kunmap_atomic(base);
1851         unpin_user_pages_dirty_lock(&page, 1, true);
1852         return 0;
1853 }
1854
1855 static int log_write(void __user *log_base,
1856                      u64 write_address, u64 write_length)
1857 {
1858         u64 write_page = write_address / VHOST_PAGE_SIZE;
1859         int r;
1860
1861         if (!write_length)
1862                 return 0;
1863         write_length += write_address % VHOST_PAGE_SIZE;
1864         for (;;) {
1865                 u64 base = (u64)(unsigned long)log_base;
1866                 u64 log = base + write_page / 8;
1867                 int bit = write_page % 8;
1868                 if ((u64)(unsigned long)log != log)
1869                         return -EFAULT;
1870                 r = set_bit_to_user(bit, (void __user *)(unsigned long)log);
1871                 if (r < 0)
1872                         return r;
1873                 if (write_length <= VHOST_PAGE_SIZE)
1874                         break;
1875                 write_length -= VHOST_PAGE_SIZE;
1876                 write_page += 1;
1877         }
1878         return r;
1879 }
1880
1881 static int log_write_hva(struct vhost_virtqueue *vq, u64 hva, u64 len)
1882 {
1883         struct vhost_iotlb *umem = vq->umem;
1884         struct vhost_iotlb_map *u;
1885         u64 start, end, l, min;
1886         int r;
1887         bool hit = false;
1888
1889         while (len) {
1890                 min = len;
1891                 /* More than one GPAs can be mapped into a single HVA. So
1892                  * iterate all possible umems here to be safe.
1893                  */
1894                 list_for_each_entry(u, &umem->list, link) {
1895                         if (u->addr > hva - 1 + len ||
1896                             u->addr - 1 + u->size < hva)
1897                                 continue;
1898                         start = max(u->addr, hva);
1899                         end = min(u->addr - 1 + u->size, hva - 1 + len);
1900                         l = end - start + 1;
1901                         r = log_write(vq->log_base,
1902                                       u->start + start - u->addr,
1903                                       l);
1904                         if (r < 0)
1905                                 return r;
1906                         hit = true;
1907                         min = min(l, min);
1908                 }
1909
1910                 if (!hit)
1911                         return -EFAULT;
1912
1913                 len -= min;
1914                 hva += min;
1915         }
1916
1917         return 0;
1918 }
1919
1920 static int log_used(struct vhost_virtqueue *vq, u64 used_offset, u64 len)
1921 {
1922         struct iovec *iov = vq->log_iov;
1923         int i, ret;
1924
1925         if (!vq->iotlb)
1926                 return log_write(vq->log_base, vq->log_addr + used_offset, len);
1927
1928         ret = translate_desc(vq, (uintptr_t)vq->used + used_offset,
1929                              len, iov, 64, VHOST_ACCESS_WO);
1930         if (ret < 0)
1931                 return ret;
1932
1933         for (i = 0; i < ret; i++) {
1934                 ret = log_write_hva(vq, (uintptr_t)iov[i].iov_base,
1935                                     iov[i].iov_len);
1936                 if (ret)
1937                         return ret;
1938         }
1939
1940         return 0;
1941 }
1942
1943 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
1944                     unsigned int log_num, u64 len, struct iovec *iov, int count)
1945 {
1946         int i, r;
1947
1948         /* Make sure data written is seen before log. */
1949         smp_wmb();
1950
1951         if (vq->iotlb) {
1952                 for (i = 0; i < count; i++) {
1953                         r = log_write_hva(vq, (uintptr_t)iov[i].iov_base,
1954                                           iov[i].iov_len);
1955                         if (r < 0)
1956                                 return r;
1957                 }
1958                 return 0;
1959         }
1960
1961         for (i = 0; i < log_num; ++i) {
1962                 u64 l = min(log[i].len, len);
1963                 r = log_write(vq->log_base, log[i].addr, l);
1964                 if (r < 0)
1965                         return r;
1966                 len -= l;
1967                 if (!len) {
1968                         if (vq->log_ctx)
1969                                 eventfd_signal(vq->log_ctx, 1);
1970                         return 0;
1971                 }
1972         }
1973         /* Length written exceeds what we have stored. This is a bug. */
1974         BUG();
1975         return 0;
1976 }
1977 EXPORT_SYMBOL_GPL(vhost_log_write);
1978
1979 static int vhost_update_used_flags(struct vhost_virtqueue *vq)
1980 {
1981         void __user *used;
1982         if (vhost_put_used_flags(vq))
1983                 return -EFAULT;
1984         if (unlikely(vq->log_used)) {
1985                 /* Make sure the flag is seen before log. */
1986                 smp_wmb();
1987                 /* Log used flag write. */
1988                 used = &vq->used->flags;
1989                 log_used(vq, (used - (void __user *)vq->used),
1990                          sizeof vq->used->flags);
1991                 if (vq->log_ctx)
1992                         eventfd_signal(vq->log_ctx, 1);
1993         }
1994         return 0;
1995 }
1996
1997 static int vhost_update_avail_event(struct vhost_virtqueue *vq)
1998 {
1999         if (vhost_put_avail_event(vq))
2000                 return -EFAULT;
2001         if (unlikely(vq->log_used)) {
2002                 void __user *used;
2003                 /* Make sure the event is seen before log. */
2004                 smp_wmb();
2005                 /* Log avail event write */
2006                 used = vhost_avail_event(vq);
2007                 log_used(vq, (used - (void __user *)vq->used),
2008                          sizeof *vhost_avail_event(vq));
2009                 if (vq->log_ctx)
2010                         eventfd_signal(vq->log_ctx, 1);
2011         }
2012         return 0;
2013 }
2014
2015 int vhost_vq_init_access(struct vhost_virtqueue *vq)
2016 {
2017         __virtio16 last_used_idx;
2018         int r;
2019         bool is_le = vq->is_le;
2020
2021         if (!vq->private_data)
2022                 return 0;
2023
2024         vhost_init_is_le(vq);
2025
2026         r = vhost_update_used_flags(vq);
2027         if (r)
2028                 goto err;
2029         vq->signalled_used_valid = false;
2030         if (!vq->iotlb &&
2031             !access_ok(&vq->used->idx, sizeof vq->used->idx)) {
2032                 r = -EFAULT;
2033                 goto err;
2034         }
2035         r = vhost_get_used_idx(vq, &last_used_idx);
2036         if (r) {
2037                 vq_err(vq, "Can't access used idx at %p\n",
2038                        &vq->used->idx);
2039                 goto err;
2040         }
2041         vq->last_used_idx = vhost16_to_cpu(vq, last_used_idx);
2042         return 0;
2043
2044 err:
2045         vq->is_le = is_le;
2046         return r;
2047 }
2048 EXPORT_SYMBOL_GPL(vhost_vq_init_access);
2049
2050 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
2051                           struct iovec iov[], int iov_size, int access)
2052 {
2053         const struct vhost_iotlb_map *map;
2054         struct vhost_dev *dev = vq->dev;
2055         struct vhost_iotlb *umem = dev->iotlb ? dev->iotlb : dev->umem;
2056         struct iovec *_iov;
2057         u64 s = 0, last = addr + len - 1;
2058         int ret = 0;
2059
2060         while ((u64)len > s) {
2061                 u64 size;
2062                 if (unlikely(ret >= iov_size)) {
2063                         ret = -ENOBUFS;
2064                         break;
2065                 }
2066
2067                 map = vhost_iotlb_itree_first(umem, addr, last);
2068                 if (map == NULL || map->start > addr) {
2069                         if (umem != dev->iotlb) {
2070                                 ret = -EFAULT;
2071                                 break;
2072                         }
2073                         ret = -EAGAIN;
2074                         break;
2075                 } else if (!(map->perm & access)) {
2076                         ret = -EPERM;
2077                         break;
2078                 }
2079
2080                 _iov = iov + ret;
2081                 size = map->size - addr + map->start;
2082                 _iov->iov_len = min((u64)len - s, size);
2083                 _iov->iov_base = (void __user *)(unsigned long)
2084                                  (map->addr + addr - map->start);
2085                 s += size;
2086                 addr += size;
2087                 ++ret;
2088         }
2089
2090         if (ret == -EAGAIN)
2091                 vhost_iotlb_miss(vq, addr, access);
2092         return ret;
2093 }
2094
2095 /* Each buffer in the virtqueues is actually a chain of descriptors.  This
2096  * function returns the next descriptor in the chain,
2097  * or -1U if we're at the end. */
2098 static unsigned next_desc(struct vhost_virtqueue *vq, struct vring_desc *desc)
2099 {
2100         unsigned int next;
2101
2102         /* If this descriptor says it doesn't chain, we're done. */
2103         if (!(desc->flags & cpu_to_vhost16(vq, VRING_DESC_F_NEXT)))
2104                 return -1U;
2105
2106         /* Check they're not leading us off end of descriptors. */
2107         next = vhost16_to_cpu(vq, READ_ONCE(desc->next));
2108         return next;
2109 }
2110
2111 static int get_indirect(struct vhost_virtqueue *vq,
2112                         struct iovec iov[], unsigned int iov_size,
2113                         unsigned int *out_num, unsigned int *in_num,
2114                         struct vhost_log *log, unsigned int *log_num,
2115                         struct vring_desc *indirect)
2116 {
2117         struct vring_desc desc;
2118         unsigned int i = 0, count, found = 0;
2119         u32 len = vhost32_to_cpu(vq, indirect->len);
2120         struct iov_iter from;
2121         int ret, access;
2122
2123         /* Sanity check */
2124         if (unlikely(len % sizeof desc)) {
2125                 vq_err(vq, "Invalid length in indirect descriptor: "
2126                        "len 0x%llx not multiple of 0x%zx\n",
2127                        (unsigned long long)len,
2128                        sizeof desc);
2129                 return -EINVAL;
2130         }
2131
2132         ret = translate_desc(vq, vhost64_to_cpu(vq, indirect->addr), len, vq->indirect,
2133                              UIO_MAXIOV, VHOST_ACCESS_RO);
2134         if (unlikely(ret < 0)) {
2135                 if (ret != -EAGAIN)
2136                         vq_err(vq, "Translation failure %d in indirect.\n", ret);
2137                 return ret;
2138         }
2139         iov_iter_init(&from, ITER_SOURCE, vq->indirect, ret, len);
2140         count = len / sizeof desc;
2141         /* Buffers are chained via a 16 bit next field, so
2142          * we can have at most 2^16 of these. */
2143         if (unlikely(count > USHRT_MAX + 1)) {
2144                 vq_err(vq, "Indirect buffer length too big: %d\n",
2145                        indirect->len);
2146                 return -E2BIG;
2147         }
2148
2149         do {
2150                 unsigned iov_count = *in_num + *out_num;
2151                 if (unlikely(++found > count)) {
2152                         vq_err(vq, "Loop detected: last one at %u "
2153                                "indirect size %u\n",
2154                                i, count);
2155                         return -EINVAL;
2156                 }
2157                 if (unlikely(!copy_from_iter_full(&desc, sizeof(desc), &from))) {
2158                         vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n",
2159                                i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
2160                         return -EINVAL;
2161                 }
2162                 if (unlikely(desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT))) {
2163                         vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n",
2164                                i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
2165                         return -EINVAL;
2166                 }
2167
2168                 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
2169                         access = VHOST_ACCESS_WO;
2170                 else
2171                         access = VHOST_ACCESS_RO;
2172
2173                 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
2174                                      vhost32_to_cpu(vq, desc.len), iov + iov_count,
2175                                      iov_size - iov_count, access);
2176                 if (unlikely(ret < 0)) {
2177                         if (ret != -EAGAIN)
2178                                 vq_err(vq, "Translation failure %d indirect idx %d\n",
2179                                         ret, i);
2180                         return ret;
2181                 }
2182                 /* If this is an input descriptor, increment that count. */
2183                 if (access == VHOST_ACCESS_WO) {
2184                         *in_num += ret;
2185                         if (unlikely(log && ret)) {
2186                                 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
2187                                 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
2188                                 ++*log_num;
2189                         }
2190                 } else {
2191                         /* If it's an output descriptor, they're all supposed
2192                          * to come before any input descriptors. */
2193                         if (unlikely(*in_num)) {
2194                                 vq_err(vq, "Indirect descriptor "
2195                                        "has out after in: idx %d\n", i);
2196                                 return -EINVAL;
2197                         }
2198                         *out_num += ret;
2199                 }
2200         } while ((i = next_desc(vq, &desc)) != -1);
2201         return 0;
2202 }
2203
2204 /* This looks in the virtqueue and for the first available buffer, and converts
2205  * it to an iovec for convenient access.  Since descriptors consist of some
2206  * number of output then some number of input descriptors, it's actually two
2207  * iovecs, but we pack them into one and note how many of each there were.
2208  *
2209  * This function returns the descriptor number found, or vq->num (which is
2210  * never a valid descriptor number) if none was found.  A negative code is
2211  * returned on error. */
2212 int vhost_get_vq_desc(struct vhost_virtqueue *vq,
2213                       struct iovec iov[], unsigned int iov_size,
2214                       unsigned int *out_num, unsigned int *in_num,
2215                       struct vhost_log *log, unsigned int *log_num)
2216 {
2217         struct vring_desc desc;
2218         unsigned int i, head, found = 0;
2219         u16 last_avail_idx;
2220         __virtio16 avail_idx;
2221         __virtio16 ring_head;
2222         int ret, access;
2223
2224         /* Check it isn't doing very strange things with descriptor numbers. */
2225         last_avail_idx = vq->last_avail_idx;
2226
2227         if (vq->avail_idx == vq->last_avail_idx) {
2228                 if (unlikely(vhost_get_avail_idx(vq, &avail_idx))) {
2229                         vq_err(vq, "Failed to access avail idx at %p\n",
2230                                 &vq->avail->idx);
2231                         return -EFAULT;
2232                 }
2233                 vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
2234
2235                 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
2236                         vq_err(vq, "Guest moved used index from %u to %u",
2237                                 last_avail_idx, vq->avail_idx);
2238                         return -EFAULT;
2239                 }
2240
2241                 /* If there's nothing new since last we looked, return
2242                  * invalid.
2243                  */
2244                 if (vq->avail_idx == last_avail_idx)
2245                         return vq->num;
2246
2247                 /* Only get avail ring entries after they have been
2248                  * exposed by guest.
2249                  */
2250                 smp_rmb();
2251         }
2252
2253         /* Grab the next descriptor number they're advertising, and increment
2254          * the index we've seen. */
2255         if (unlikely(vhost_get_avail_head(vq, &ring_head, last_avail_idx))) {
2256                 vq_err(vq, "Failed to read head: idx %d address %p\n",
2257                        last_avail_idx,
2258                        &vq->avail->ring[last_avail_idx % vq->num]);
2259                 return -EFAULT;
2260         }
2261
2262         head = vhost16_to_cpu(vq, ring_head);
2263
2264         /* If their number is silly, that's an error. */
2265         if (unlikely(head >= vq->num)) {
2266                 vq_err(vq, "Guest says index %u > %u is available",
2267                        head, vq->num);
2268                 return -EINVAL;
2269         }
2270
2271         /* When we start there are none of either input nor output. */
2272         *out_num = *in_num = 0;
2273         if (unlikely(log))
2274                 *log_num = 0;
2275
2276         i = head;
2277         do {
2278                 unsigned iov_count = *in_num + *out_num;
2279                 if (unlikely(i >= vq->num)) {
2280                         vq_err(vq, "Desc index is %u > %u, head = %u",
2281                                i, vq->num, head);
2282                         return -EINVAL;
2283                 }
2284                 if (unlikely(++found > vq->num)) {
2285                         vq_err(vq, "Loop detected: last one at %u "
2286                                "vq size %u head %u\n",
2287                                i, vq->num, head);
2288                         return -EINVAL;
2289                 }
2290                 ret = vhost_get_desc(vq, &desc, i);
2291                 if (unlikely(ret)) {
2292                         vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
2293                                i, vq->desc + i);
2294                         return -EFAULT;
2295                 }
2296                 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT)) {
2297                         ret = get_indirect(vq, iov, iov_size,
2298                                            out_num, in_num,
2299                                            log, log_num, &desc);
2300                         if (unlikely(ret < 0)) {
2301                                 if (ret != -EAGAIN)
2302                                         vq_err(vq, "Failure detected "
2303                                                 "in indirect descriptor at idx %d\n", i);
2304                                 return ret;
2305                         }
2306                         continue;
2307                 }
2308
2309                 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
2310                         access = VHOST_ACCESS_WO;
2311                 else
2312                         access = VHOST_ACCESS_RO;
2313                 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
2314                                      vhost32_to_cpu(vq, desc.len), iov + iov_count,
2315                                      iov_size - iov_count, access);
2316                 if (unlikely(ret < 0)) {
2317                         if (ret != -EAGAIN)
2318                                 vq_err(vq, "Translation failure %d descriptor idx %d\n",
2319                                         ret, i);
2320                         return ret;
2321                 }
2322                 if (access == VHOST_ACCESS_WO) {
2323                         /* If this is an input descriptor,
2324                          * increment that count. */
2325                         *in_num += ret;
2326                         if (unlikely(log && ret)) {
2327                                 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
2328                                 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
2329                                 ++*log_num;
2330                         }
2331                 } else {
2332                         /* If it's an output descriptor, they're all supposed
2333                          * to come before any input descriptors. */
2334                         if (unlikely(*in_num)) {
2335                                 vq_err(vq, "Descriptor has out after in: "
2336                                        "idx %d\n", i);
2337                                 return -EINVAL;
2338                         }
2339                         *out_num += ret;
2340                 }
2341         } while ((i = next_desc(vq, &desc)) != -1);
2342
2343         /* On success, increment avail index. */
2344         vq->last_avail_idx++;
2345
2346         /* Assume notifications from guest are disabled at this point,
2347          * if they aren't we would need to update avail_event index. */
2348         BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
2349         return head;
2350 }
2351 EXPORT_SYMBOL_GPL(vhost_get_vq_desc);
2352
2353 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
2354 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
2355 {
2356         vq->last_avail_idx -= n;
2357 }
2358 EXPORT_SYMBOL_GPL(vhost_discard_vq_desc);
2359
2360 /* After we've used one of their buffers, we tell them about it.  We'll then
2361  * want to notify the guest, using eventfd. */
2362 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
2363 {
2364         struct vring_used_elem heads = {
2365                 cpu_to_vhost32(vq, head),
2366                 cpu_to_vhost32(vq, len)
2367         };
2368
2369         return vhost_add_used_n(vq, &heads, 1);
2370 }
2371 EXPORT_SYMBOL_GPL(vhost_add_used);
2372
2373 static int __vhost_add_used_n(struct vhost_virtqueue *vq,
2374                             struct vring_used_elem *heads,
2375                             unsigned count)
2376 {
2377         vring_used_elem_t __user *used;
2378         u16 old, new;
2379         int start;
2380
2381         start = vq->last_used_idx & (vq->num - 1);
2382         used = vq->used->ring + start;
2383         if (vhost_put_used(vq, heads, start, count)) {
2384                 vq_err(vq, "Failed to write used");
2385                 return -EFAULT;
2386         }
2387         if (unlikely(vq->log_used)) {
2388                 /* Make sure data is seen before log. */
2389                 smp_wmb();
2390                 /* Log used ring entry write. */
2391                 log_used(vq, ((void __user *)used - (void __user *)vq->used),
2392                          count * sizeof *used);
2393         }
2394         old = vq->last_used_idx;
2395         new = (vq->last_used_idx += count);
2396         /* If the driver never bothers to signal in a very long while,
2397          * used index might wrap around. If that happens, invalidate
2398          * signalled_used index we stored. TODO: make sure driver
2399          * signals at least once in 2^16 and remove this. */
2400         if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old)))
2401                 vq->signalled_used_valid = false;
2402         return 0;
2403 }
2404
2405 /* After we've used one of their buffers, we tell them about it.  We'll then
2406  * want to notify the guest, using eventfd. */
2407 int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
2408                      unsigned count)
2409 {
2410         int start, n, r;
2411
2412         start = vq->last_used_idx & (vq->num - 1);
2413         n = vq->num - start;
2414         if (n < count) {
2415                 r = __vhost_add_used_n(vq, heads, n);
2416                 if (r < 0)
2417                         return r;
2418                 heads += n;
2419                 count -= n;
2420         }
2421         r = __vhost_add_used_n(vq, heads, count);
2422
2423         /* Make sure buffer is written before we update index. */
2424         smp_wmb();
2425         if (vhost_put_used_idx(vq)) {
2426                 vq_err(vq, "Failed to increment used idx");
2427                 return -EFAULT;
2428         }
2429         if (unlikely(vq->log_used)) {
2430                 /* Make sure used idx is seen before log. */
2431                 smp_wmb();
2432                 /* Log used index update. */
2433                 log_used(vq, offsetof(struct vring_used, idx),
2434                          sizeof vq->used->idx);
2435                 if (vq->log_ctx)
2436                         eventfd_signal(vq->log_ctx, 1);
2437         }
2438         return r;
2439 }
2440 EXPORT_SYMBOL_GPL(vhost_add_used_n);
2441
2442 static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2443 {
2444         __u16 old, new;
2445         __virtio16 event;
2446         bool v;
2447         /* Flush out used index updates. This is paired
2448          * with the barrier that the Guest executes when enabling
2449          * interrupts. */
2450         smp_mb();
2451
2452         if (vhost_has_feature(vq, VIRTIO_F_NOTIFY_ON_EMPTY) &&
2453             unlikely(vq->avail_idx == vq->last_avail_idx))
2454                 return true;
2455
2456         if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2457                 __virtio16 flags;
2458                 if (vhost_get_avail_flags(vq, &flags)) {
2459                         vq_err(vq, "Failed to get flags");
2460                         return true;
2461                 }
2462                 return !(flags & cpu_to_vhost16(vq, VRING_AVAIL_F_NO_INTERRUPT));
2463         }
2464         old = vq->signalled_used;
2465         v = vq->signalled_used_valid;
2466         new = vq->signalled_used = vq->last_used_idx;
2467         vq->signalled_used_valid = true;
2468
2469         if (unlikely(!v))
2470                 return true;
2471
2472         if (vhost_get_used_event(vq, &event)) {
2473                 vq_err(vq, "Failed to get used event idx");
2474                 return true;
2475         }
2476         return vring_need_event(vhost16_to_cpu(vq, event), new, old);
2477 }
2478
2479 /* This actually signals the guest, using eventfd. */
2480 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2481 {
2482         /* Signal the Guest tell them we used something up. */
2483         if (vq->call_ctx.ctx && vhost_notify(dev, vq))
2484                 eventfd_signal(vq->call_ctx.ctx, 1);
2485 }
2486 EXPORT_SYMBOL_GPL(vhost_signal);
2487
2488 /* And here's the combo meal deal.  Supersize me! */
2489 void vhost_add_used_and_signal(struct vhost_dev *dev,
2490                                struct vhost_virtqueue *vq,
2491                                unsigned int head, int len)
2492 {
2493         vhost_add_used(vq, head, len);
2494         vhost_signal(dev, vq);
2495 }
2496 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal);
2497
2498 /* multi-buffer version of vhost_add_used_and_signal */
2499 void vhost_add_used_and_signal_n(struct vhost_dev *dev,
2500                                  struct vhost_virtqueue *vq,
2501                                  struct vring_used_elem *heads, unsigned count)
2502 {
2503         vhost_add_used_n(vq, heads, count);
2504         vhost_signal(dev, vq);
2505 }
2506 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n);
2507
2508 /* return true if we're sure that avaiable ring is empty */
2509 bool vhost_vq_avail_empty(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2510 {
2511         __virtio16 avail_idx;
2512         int r;
2513
2514         if (vq->avail_idx != vq->last_avail_idx)
2515                 return false;
2516
2517         r = vhost_get_avail_idx(vq, &avail_idx);
2518         if (unlikely(r))
2519                 return false;
2520         vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
2521
2522         return vq->avail_idx == vq->last_avail_idx;
2523 }
2524 EXPORT_SYMBOL_GPL(vhost_vq_avail_empty);
2525
2526 /* OK, now we need to know about added descriptors. */
2527 bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2528 {
2529         __virtio16 avail_idx;
2530         int r;
2531
2532         if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
2533                 return false;
2534         vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
2535         if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2536                 r = vhost_update_used_flags(vq);
2537                 if (r) {
2538                         vq_err(vq, "Failed to enable notification at %p: %d\n",
2539                                &vq->used->flags, r);
2540                         return false;
2541                 }
2542         } else {
2543                 r = vhost_update_avail_event(vq);
2544                 if (r) {
2545                         vq_err(vq, "Failed to update avail event index at %p: %d\n",
2546                                vhost_avail_event(vq), r);
2547                         return false;
2548                 }
2549         }
2550         /* They could have slipped one in as we were doing that: make
2551          * sure it's written, then check again. */
2552         smp_mb();
2553         r = vhost_get_avail_idx(vq, &avail_idx);
2554         if (r) {
2555                 vq_err(vq, "Failed to check avail idx at %p: %d\n",
2556                        &vq->avail->idx, r);
2557                 return false;
2558         }
2559         vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
2560
2561         return vq->avail_idx != vq->last_avail_idx;
2562 }
2563 EXPORT_SYMBOL_GPL(vhost_enable_notify);
2564
2565 /* We don't need to be notified again. */
2566 void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2567 {
2568         int r;
2569
2570         if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
2571                 return;
2572         vq->used_flags |= VRING_USED_F_NO_NOTIFY;
2573         if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2574                 r = vhost_update_used_flags(vq);
2575                 if (r)
2576                         vq_err(vq, "Failed to disable notification at %p: %d\n",
2577                                &vq->used->flags, r);
2578         }
2579 }
2580 EXPORT_SYMBOL_GPL(vhost_disable_notify);
2581
2582 /* Create a new message. */
2583 struct vhost_msg_node *vhost_new_msg(struct vhost_virtqueue *vq, int type)
2584 {
2585         struct vhost_msg_node *node = kmalloc(sizeof *node, GFP_KERNEL);
2586         if (!node)
2587                 return NULL;
2588
2589         /* Make sure all padding within the structure is initialized. */
2590         memset(&node->msg, 0, sizeof node->msg);
2591         node->vq = vq;
2592         node->msg.type = type;
2593         return node;
2594 }
2595 EXPORT_SYMBOL_GPL(vhost_new_msg);
2596
2597 void vhost_enqueue_msg(struct vhost_dev *dev, struct list_head *head,
2598                        struct vhost_msg_node *node)
2599 {
2600         spin_lock(&dev->iotlb_lock);
2601         list_add_tail(&node->node, head);
2602         spin_unlock(&dev->iotlb_lock);
2603
2604         wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
2605 }
2606 EXPORT_SYMBOL_GPL(vhost_enqueue_msg);
2607
2608 struct vhost_msg_node *vhost_dequeue_msg(struct vhost_dev *dev,
2609                                          struct list_head *head)
2610 {
2611         struct vhost_msg_node *node = NULL;
2612
2613         spin_lock(&dev->iotlb_lock);
2614         if (!list_empty(head)) {
2615                 node = list_first_entry(head, struct vhost_msg_node,
2616                                         node);
2617                 list_del(&node->node);
2618         }
2619         spin_unlock(&dev->iotlb_lock);
2620
2621         return node;
2622 }
2623 EXPORT_SYMBOL_GPL(vhost_dequeue_msg);
2624
2625 void vhost_set_backend_features(struct vhost_dev *dev, u64 features)
2626 {
2627         struct vhost_virtqueue *vq;
2628         int i;
2629
2630         mutex_lock(&dev->mutex);
2631         for (i = 0; i < dev->nvqs; ++i) {
2632                 vq = dev->vqs[i];
2633                 mutex_lock(&vq->mutex);
2634                 vq->acked_backend_features = features;
2635                 mutex_unlock(&vq->mutex);
2636         }
2637         mutex_unlock(&dev->mutex);
2638 }
2639 EXPORT_SYMBOL_GPL(vhost_set_backend_features);
2640
2641 static int __init vhost_init(void)
2642 {
2643         return 0;
2644 }
2645
2646 static void __exit vhost_exit(void)
2647 {
2648 }
2649
2650 module_init(vhost_init);
2651 module_exit(vhost_exit);
2652
2653 MODULE_VERSION("0.0.1");
2654 MODULE_LICENSE("GPL v2");
2655 MODULE_AUTHOR("Michael S. Tsirkin");
2656 MODULE_DESCRIPTION("Host kernel accelerator for virtio");