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/mmu_context.h>
  18 #include <linux/miscdevice.h>
  19 #include <linux/mutex.h>
  20 #include <linux/poll.h>
  21 #include <linux/file.h>
  22 #include <linux/highmem.h>
  23 #include <linux/slab.h>
  24 #include <linux/vmalloc.h>
  25 #include <linux/kthread.h>
  26 #include <linux/cgroup.h>
  27 #include <linux/module.h>
  28 #include <linux/sort.h>
  29 #include <linux/sched/mm.h>
  30 #include <linux/sched/signal.h>
  31 #include <linux/interval_tree_generic.h>
  32 #include <linux/nospec.h>
  33 #include <linux/kcov.h>
  34
  35 #include "vhost.h"
  36
  37 static ushort max_mem_regions = 64;
  38 module_param(max_mem_regions, ushort, 0444);
  39 MODULE_PARM_DESC(max_mem_regions,
  40         "Maximum number of memory regions in memory map. (default: 64)");
  41 static int max_iotlb_entries = 2048;
  42 module_param(max_iotlb_entries, int, 0444);
  43 MODULE_PARM_DESC(max_iotlb_entries,
  44         "Maximum number of iotlb entries. (default: 2048)");
  45
  46 enum {
  47         VHOST_MEMORY_F_LOG = 0x1,
  48 };
  49
  50 #define vhost_used_event(vq) ((__virtio16 __user *)&vq->avail->ring[vq->num])
  51 #define vhost_avail_event(vq) ((__virtio16 __user *)&vq->used->ring[vq->num])
  52
  53 INTERVAL_TREE_DEFINE(struct vhost_umem_node,
  54                      rb, __u64, __subtree_last,
  55                      START, LAST, static inline, vhost_umem_interval_tree);
  56
  57 #ifdef CONFIG_VHOST_CROSS_ENDIAN_LEGACY
  58 static void vhost_disable_cross_endian(struct vhost_virtqueue *vq)
  59 {
  60         vq->user_be = !virtio_legacy_is_little_endian();
  61 }
  62
  63 static void vhost_enable_cross_endian_big(struct vhost_virtqueue *vq)
  64 {
  65         vq->user_be = true;
  66 }
  67
  68 static void vhost_enable_cross_endian_little(struct vhost_virtqueue *vq)
  69 {
  70         vq->user_be = false;
  71 }
  72
  73 static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp)
  74 {
  75         struct vhost_vring_state s;
  76
  77         if (vq->private_data)
  78                 return -EBUSY;
  79
  80         if (copy_from_user(&s, argp, sizeof(s)))
  81                 return -EFAULT;
  82
  83         if (s.num != VHOST_VRING_LITTLE_ENDIAN &&
  84             s.num != VHOST_VRING_BIG_ENDIAN)
  85                 return -EINVAL;
  86
  87         if (s.num == VHOST_VRING_BIG_ENDIAN)
  88                 vhost_enable_cross_endian_big(vq);
  89         else
  90                 vhost_enable_cross_endian_little(vq);
  91
  92         return 0;
  93 }
  94
  95 static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx,
  96                                    int __user *argp)
  97 {
  98         struct vhost_vring_state s = {
  99                 .index = idx,
 100                 .num = vq->user_be
 101         };
 102
 103         if (copy_to_user(argp, &s, sizeof(s)))
 104                 return -EFAULT;
 105
 106         return 0;
 107 }
 108
 109 static void vhost_init_is_le(struct vhost_virtqueue *vq)
 110 {
 111         /* Note for legacy virtio: user_be is initialized at reset time
 112          * according to the host endianness. If userspace does not set an
 113          * explicit endianness, the default behavior is native endian, as
 114          * expected by legacy virtio.
 115          */
 116         vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1) || !vq->user_be;
 117 }
 118 #else
 119 static void vhost_disable_cross_endian(struct vhost_virtqueue *vq)
 120 {
 121 }
 122
 123 static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp)
 124 {
 125         return -ENOIOCTLCMD;
 126 }
 127
 128 static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx,
 129                                    int __user *argp)
 130 {
 131         return -ENOIOCTLCMD;
 132 }
 133
 134 static void vhost_init_is_le(struct vhost_virtqueue *vq)
 135 {
 136         vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1)
 137                 || virtio_legacy_is_little_endian();
 138 }
 139 #endif /* CONFIG_VHOST_CROSS_ENDIAN_LEGACY */
 140
 141 static void vhost_reset_is_le(struct vhost_virtqueue *vq)
 142 {
 143         vhost_init_is_le(vq);
 144 }
 145
 146 struct vhost_flush_struct {
 147         struct vhost_work work;
 148         struct completion wait_event;
 149 };
 150
 151 static void vhost_flush_work(struct vhost_work *work)
 152 {
 153         struct vhost_flush_struct *s;
 154
 155         s = container_of(work, struct vhost_flush_struct, work);
 156         complete(&s->wait_event);
 157 }
 158
 159 static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh,
 160                             poll_table *pt)
 161 {
 162         struct vhost_poll *poll;
 163
 164         poll = container_of(pt, struct vhost_poll, table);
 165         poll->wqh = wqh;
 166         add_wait_queue(wqh, &poll->wait);
 167 }
 168
 169 static int vhost_poll_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync,
 170                              void *key)
 171 {
 172         struct vhost_poll *poll = container_of(wait, struct vhost_poll, wait);
 173
 174         if (!(key_to_poll(key) & poll->mask))
 175                 return 0;
 176
 177         vhost_poll_queue(poll);
 178         return 0;
 179 }
 180
 181 void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn)
 182 {
 183         clear_bit(VHOST_WORK_QUEUED, &work->flags);
 184         work->fn = fn;
 185 }
 186 EXPORT_SYMBOL_GPL(vhost_work_init);
 187
 188 /* Init poll structure */
 189 void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
 190                      __poll_t mask, struct vhost_dev *dev)
 191 {
 192         init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup);
 193         init_poll_funcptr(&poll->table, vhost_poll_func);
 194         poll->mask = mask;
 195         poll->dev = dev;
 196         poll->wqh = NULL;
 197
 198         vhost_work_init(&poll->work, fn);
 199 }
 200 EXPORT_SYMBOL_GPL(vhost_poll_init);
 201
 202 /* Start polling a file. We add ourselves to file's wait queue. The caller must
 203  * keep a reference to a file until after vhost_poll_stop is called. */
 204 int vhost_poll_start(struct vhost_poll *poll, struct file *file)
 205 {
 206         __poll_t mask;
 207
 208         if (poll->wqh)
 209                 return 0;
 210
 211         mask = vfs_poll(file, &poll->table);
 212         if (mask)
 213                 vhost_poll_wakeup(&poll->wait, 0, 0, poll_to_key(mask));
 214         if (mask & EPOLLERR) {
 215                 vhost_poll_stop(poll);
 216                 return -EINVAL;
 217         }
 218
 219         return 0;
 220 }
 221 EXPORT_SYMBOL_GPL(vhost_poll_start);
 222
 223 /* Stop polling a file. After this function returns, it becomes safe to drop the
 224  * file reference. You must also flush afterwards. */
 225 void vhost_poll_stop(struct vhost_poll *poll)
 226 {
 227         if (poll->wqh) {
 228                 remove_wait_queue(poll->wqh, &poll->wait);
 229                 poll->wqh = NULL;
 230         }
 231 }
 232 EXPORT_SYMBOL_GPL(vhost_poll_stop);
 233
 234 void vhost_work_flush(struct vhost_dev *dev, struct vhost_work *work)
 235 {
 236         struct vhost_flush_struct flush;
 237
 238         if (dev->worker) {
 239                 init_completion(&flush.wait_event);
 240                 vhost_work_init(&flush.work, vhost_flush_work);
 241
 242                 vhost_work_queue(dev, &flush.work);
 243                 wait_for_completion(&flush.wait_event);
 244         }
 245 }
 246 EXPORT_SYMBOL_GPL(vhost_work_flush);
 247
 248 /* Flush any work that has been scheduled. When calling this, don't hold any
 249  * locks that are also used by the callback. */
 250 void vhost_poll_flush(struct vhost_poll *poll)
 251 {
 252         vhost_work_flush(poll->dev, &poll->work);
 253 }
 254 EXPORT_SYMBOL_GPL(vhost_poll_flush);
 255
 256 void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work)
 257 {
 258         if (!dev->worker)
 259                 return;
 260
 261         if (!test_and_set_bit(VHOST_WORK_QUEUED, &work->flags)) {
 262                 /* We can only add the work to the list after we're
 263                  * sure it was not in the list.
 264                  * test_and_set_bit() implies a memory barrier.
 265                  */
 266                 llist_add(&work->node, &dev->work_list);
 267                 wake_up_process(dev->worker);
 268         }
 269 }
 270 EXPORT_SYMBOL_GPL(vhost_work_queue);
 271
 272 /* A lockless hint for busy polling code to exit the loop */
 273 bool vhost_has_work(struct vhost_dev *dev)
 274 {
 275         return !llist_empty(&dev->work_list);
 276 }
 277 EXPORT_SYMBOL_GPL(vhost_has_work);
 278
 279 void vhost_poll_queue(struct vhost_poll *poll)
 280 {
 281         vhost_work_queue(poll->dev, &poll->work);
 282 }
 283 EXPORT_SYMBOL_GPL(vhost_poll_queue);
 284
 285 static void __vhost_vq_meta_reset(struct vhost_virtqueue *vq)
 286 {
 287         int j;
 288
 289         for (j = 0; j < VHOST_NUM_ADDRS; j++)
 290                 vq->meta_iotlb[j] = NULL;
 291 }
 292
 293 static void vhost_vq_meta_reset(struct vhost_dev *d)
 294 {
 295         int i;
 296
 297         for (i = 0; i < d->nvqs; ++i)
 298                 __vhost_vq_meta_reset(d->vqs[i]);
 299 }
 300
 301 static void vhost_vq_reset(struct vhost_dev *dev,
 302                            struct vhost_virtqueue *vq)
 303 {
 304         vq->num = 1;
 305         vq->desc = NULL;
 306         vq->avail = NULL;
 307         vq->used = NULL;
 308         vq->last_avail_idx = 0;
 309         vq->avail_idx = 0;
 310         vq->last_used_idx = 0;
 311         vq->signalled_used = 0;
 312         vq->signalled_used_valid = false;
 313         vq->used_flags = 0;
 314         vq->log_used = false;
 315         vq->log_addr = -1ull;
 316         vq->private_data = NULL;
 317         vq->acked_features = 0;
 318         vq->acked_backend_features = 0;
 319         vq->log_base = NULL;
 320         vq->error_ctx = NULL;
 321         vq->kick = NULL;
 322         vq->call_ctx = NULL;
 323         vq->log_ctx = NULL;
 324         vhost_reset_is_le(vq);
 325         vhost_disable_cross_endian(vq);
 326         vq->busyloop_timeout = 0;
 327         vq->umem = NULL;
 328         vq->iotlb = NULL;
 329         __vhost_vq_meta_reset(vq);
 330 }
 331
 332 static int vhost_worker(void *data)
 333 {
 334         struct vhost_dev *dev = data;
 335         struct vhost_work *work, *work_next;
 336         struct llist_node *node;
 337         mm_segment_t oldfs = get_fs();
 338
 339         set_fs(USER_DS);
 340         use_mm(dev->mm);
 341
 342         for (;;) {
 343                 /* mb paired w/ kthread_stop */
 344                 set_current_state(TASK_INTERRUPTIBLE);
 345
 346                 if (kthread_should_stop()) {
 347                         __set_current_state(TASK_RUNNING);
 348                         break;
 349                 }
 350
 351                 node = llist_del_all(&dev->work_list);
 352                 if (!node)
 353                         schedule();
 354
 355                 node = llist_reverse_order(node);
 356                 /* make sure flag is seen after deletion */
 357                 smp_wmb();
 358                 llist_for_each_entry_safe(work, work_next, node, node) {
 359                         clear_bit(VHOST_WORK_QUEUED, &work->flags);
 360                         __set_current_state(TASK_RUNNING);
 361                         kcov_remote_start_common(dev->kcov_handle);
 362                         work->fn(work);
 363                         kcov_remote_stop();
 364                         if (need_resched())
 365                                 schedule();
 366                 }
 367         }
 368         unuse_mm(dev->mm);
 369         set_fs(oldfs);
 370         return 0;
 371 }
 372
 373 static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq)
 374 {
 375         kfree(vq->indirect);
 376         vq->indirect = NULL;
 377         kfree(vq->log);
 378         vq->log = NULL;
 379         kfree(vq->heads);
 380         vq->heads = NULL;
 381 }
 382
 383 /* Helper to allocate iovec buffers for all vqs. */
 384 static long vhost_dev_alloc_iovecs(struct vhost_dev *dev)
 385 {
 386         struct vhost_virtqueue *vq;
 387         int i;
 388
 389         for (i = 0; i < dev->nvqs; ++i) {
 390                 vq = dev->vqs[i];
 391                 vq->indirect = kmalloc_array(UIO_MAXIOV,
 392                                              sizeof(*vq->indirect),
 393                                              GFP_KERNEL);
 394                 vq->log = kmalloc_array(dev->iov_limit, sizeof(*vq->log),
 395                                         GFP_KERNEL);
 396                 vq->heads = kmalloc_array(dev->iov_limit, sizeof(*vq->heads),
 397                                           GFP_KERNEL);
 398                 if (!vq->indirect || !vq->log || !vq->heads)
 399                         goto err_nomem;
 400         }
 401         return 0;
 402
 403 err_nomem:
 404         for (; i >= 0; --i)
 405                 vhost_vq_free_iovecs(dev->vqs[i]);
 406         return -ENOMEM;
 407 }
 408
 409 static void vhost_dev_free_iovecs(struct vhost_dev *dev)
 410 {
 411         int i;
 412
 413         for (i = 0; i < dev->nvqs; ++i)
 414                 vhost_vq_free_iovecs(dev->vqs[i]);
 415 }
 416
 417 bool vhost_exceeds_weight(struct vhost_virtqueue *vq,
 418                           int pkts, int total_len)
 419 {
 420         struct vhost_dev *dev = vq->dev;
 421
 422         if ((dev->byte_weight && total_len >= dev->byte_weight) ||
 423             pkts >= dev->weight) {
 424                 vhost_poll_queue(&vq->poll);
 425                 return true;
 426         }
 427
 428         return false;
 429 }
 430 EXPORT_SYMBOL_GPL(vhost_exceeds_weight);
 431
 432 static size_t vhost_get_avail_size(struct vhost_virtqueue *vq,
 433                                    unsigned int num)
 434 {
 435         size_t event __maybe_unused =
 436                vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
 437
 438         return sizeof(*vq->avail) +
 439                sizeof(*vq->avail->ring) * num + event;
 440 }
 441
 442 static size_t vhost_get_used_size(struct vhost_virtqueue *vq,
 443                                   unsigned int num)
 444 {
 445         size_t event __maybe_unused =
 446                vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
 447
 448         return sizeof(*vq->used) +
 449                sizeof(*vq->used->ring) * num + event;
 450 }
 451
 452 static size_t vhost_get_desc_size(struct vhost_virtqueue *vq,
 453                                   unsigned int num)
 454 {
 455         return sizeof(*vq->desc) * num;
 456 }
 457
 458 void vhost_dev_init(struct vhost_dev *dev,
 459                     struct vhost_virtqueue **vqs, int nvqs,
 460                     int iov_limit, int weight, int byte_weight)
 461 {
 462         struct vhost_virtqueue *vq;
 463         int i;
 464
 465         dev->vqs = vqs;
 466         dev->nvqs = nvqs;
 467         mutex_init(&dev->mutex);
 468         dev->log_ctx = NULL;
 469         dev->umem = NULL;
 470         dev->iotlb = NULL;
 471         dev->mm = NULL;
 472         dev->worker = NULL;
 473         dev->iov_limit = iov_limit;
 474         dev->weight = weight;
 475         dev->byte_weight = byte_weight;
 476         init_llist_head(&dev->work_list);
 477         init_waitqueue_head(&dev->wait);
 478         INIT_LIST_HEAD(&dev->read_list);
 479         INIT_LIST_HEAD(&dev->pending_list);
 480         spin_lock_init(&dev->iotlb_lock);
 481
 482
 483         for (i = 0; i < dev->nvqs; ++i) {
 484                 vq = dev->vqs[i];
 485                 vq->log = NULL;
 486                 vq->indirect = NULL;
 487                 vq->heads = NULL;
 488                 vq->dev = dev;
 489                 mutex_init(&vq->mutex);
 490                 vhost_vq_reset(dev, vq);
 491                 if (vq->handle_kick)
 492                         vhost_poll_init(&vq->poll, vq->handle_kick,
 493                                         EPOLLIN, dev);
 494         }
 495 }
 496 EXPORT_SYMBOL_GPL(vhost_dev_init);
 497
 498 /* Caller should have device mutex */
 499 long vhost_dev_check_owner(struct vhost_dev *dev)
 500 {
 501         /* Are you the owner? If not, I don't think you mean to do that */
 502         return dev->mm == current->mm ? 0 : -EPERM;
 503 }
 504 EXPORT_SYMBOL_GPL(vhost_dev_check_owner);
 505
 506 struct vhost_attach_cgroups_struct {
 507         struct vhost_work work;
 508         struct task_struct *owner;
 509         int ret;
 510 };
 511
 512 static void vhost_attach_cgroups_work(struct vhost_work *work)
 513 {
 514         struct vhost_attach_cgroups_struct *s;
 515
 516         s = container_of(work, struct vhost_attach_cgroups_struct, work);
 517         s->ret = cgroup_attach_task_all(s->owner, current);
 518 }
 519
 520 static int vhost_attach_cgroups(struct vhost_dev *dev)
 521 {
 522         struct vhost_attach_cgroups_struct attach;
 523
 524         attach.owner = current;
 525         vhost_work_init(&attach.work, vhost_attach_cgroups_work);
 526         vhost_work_queue(dev, &attach.work);
 527         vhost_work_flush(dev, &attach.work);
 528         return attach.ret;
 529 }
 530
 531 /* Caller should have device mutex */
 532 bool vhost_dev_has_owner(struct vhost_dev *dev)
 533 {
 534         return dev->mm;
 535 }
 536 EXPORT_SYMBOL_GPL(vhost_dev_has_owner);
 537
 538 /* Caller should have device mutex */
 539 long vhost_dev_set_owner(struct vhost_dev *dev)
 540 {
 541         struct task_struct *worker;
 542         int err;
 543
 544         /* Is there an owner already? */
 545         if (vhost_dev_has_owner(dev)) {
 546                 err = -EBUSY;
 547                 goto err_mm;
 548         }
 549
 550         /* No owner, become one */
 551         dev->mm = get_task_mm(current);
 552         dev->kcov_handle = kcov_common_handle();
 553         worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid);
 554         if (IS_ERR(worker)) {
 555                 err = PTR_ERR(worker);
 556                 goto err_worker;
 557         }
 558
 559         dev->worker = worker;
 560         wake_up_process(worker);        /* avoid contributing to loadavg */
 561
 562         err = vhost_attach_cgroups(dev);
 563         if (err)
 564                 goto err_cgroup;
 565
 566         err = vhost_dev_alloc_iovecs(dev);
 567         if (err)
 568                 goto err_cgroup;
 569
 570         return 0;
 571 err_cgroup:
 572         kthread_stop(worker);
 573         dev->worker = NULL;
 574 err_worker:
 575         if (dev->mm)
 576                 mmput(dev->mm);
 577         dev->mm = NULL;
 578         dev->kcov_handle = 0;
 579 err_mm:
 580         return err;
 581 }
 582 EXPORT_SYMBOL_GPL(vhost_dev_set_owner);
 583
 584 struct vhost_umem *vhost_dev_reset_owner_prepare(void)
 585 {
 586         return kvzalloc(sizeof(struct vhost_umem), GFP_KERNEL);
 587 }
 588 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner_prepare);
 589
 590 /* Caller should have device mutex */
 591 void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_umem *umem)
 592 {
 593         int i;
 594
 595         vhost_dev_cleanup(dev);
 596
 597         /* Restore memory to default empty mapping. */
 598         INIT_LIST_HEAD(&umem->umem_list);
 599         dev->umem = umem;
 600         /* We don't need VQ locks below since vhost_dev_cleanup makes sure
 601          * VQs aren't running.
 602          */
 603         for (i = 0; i < dev->nvqs; ++i)
 604                 dev->vqs[i]->umem = umem;
 605 }
 606 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner);
 607
 608 void vhost_dev_stop(struct vhost_dev *dev)
 609 {
 610         int i;
 611
 612         for (i = 0; i < dev->nvqs; ++i) {
 613                 if (dev->vqs[i]->kick && dev->vqs[i]->handle_kick) {
 614                         vhost_poll_stop(&dev->vqs[i]->poll);
 615                         vhost_poll_flush(&dev->vqs[i]->poll);
 616                 }
 617         }
 618 }
 619 EXPORT_SYMBOL_GPL(vhost_dev_stop);
 620
 621 static void vhost_umem_free(struct vhost_umem *umem,
 622                             struct vhost_umem_node *node)
 623 {
 624         vhost_umem_interval_tree_remove(node, &umem->umem_tree);
 625         list_del(&node->link);
 626         kfree(node);
 627         umem->numem--;
 628 }
 629
 630 static void vhost_umem_clean(struct vhost_umem *umem)
 631 {
 632         struct vhost_umem_node *node, *tmp;
 633
 634         if (!umem)
 635                 return;
 636
 637         list_for_each_entry_safe(node, tmp, &umem->umem_list, link)
 638                 vhost_umem_free(umem, node);
 639
 640         kvfree(umem);
 641 }
 642
 643 static void vhost_clear_msg(struct vhost_dev *dev)
 644 {
 645         struct vhost_msg_node *node, *n;
 646
 647         spin_lock(&dev->iotlb_lock);
 648
 649         list_for_each_entry_safe(node, n, &dev->read_list, node) {
 650                 list_del(&node->node);
 651                 kfree(node);
 652         }
 653
 654         list_for_each_entry_safe(node, n, &dev->pending_list, node) {
 655                 list_del(&node->node);
 656                 kfree(node);
 657         }
 658
 659         spin_unlock(&dev->iotlb_lock);
 660 }
 661
 662 void vhost_dev_cleanup(struct vhost_dev *dev)
 663 {
 664         int i;
 665
 666         for (i = 0; i < dev->nvqs; ++i) {
 667                 if (dev->vqs[i]->error_ctx)
 668                         eventfd_ctx_put(dev->vqs[i]->error_ctx);
 669                 if (dev->vqs[i]->kick)
 670                         fput(dev->vqs[i]->kick);
 671                 if (dev->vqs[i]->call_ctx)
 672                         eventfd_ctx_put(dev->vqs[i]->call_ctx);
 673                 vhost_vq_reset(dev, dev->vqs[i]);
 674         }
 675         vhost_dev_free_iovecs(dev);
 676         if (dev->log_ctx)
 677                 eventfd_ctx_put(dev->log_ctx);
 678         dev->log_ctx = NULL;
 679         /* No one will access memory at this point */
 680         vhost_umem_clean(dev->umem);
 681         dev->umem = NULL;
 682         vhost_umem_clean(dev->iotlb);
 683         dev->iotlb = NULL;
 684         vhost_clear_msg(dev);
 685         wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
 686         WARN_ON(!llist_empty(&dev->work_list));
 687         if (dev->worker) {
 688                 kthread_stop(dev->worker);
 689                 dev->worker = NULL;
 690                 dev->kcov_handle = 0;
 691         }
 692         if (dev->mm)
 693                 mmput(dev->mm);
 694         dev->mm = NULL;
 695 }
 696 EXPORT_SYMBOL_GPL(vhost_dev_cleanup);
 697
 698 static bool log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
 699 {
 700         u64 a = addr / VHOST_PAGE_SIZE / 8;
 701
 702         /* Make sure 64 bit math will not overflow. */
 703         if (a > ULONG_MAX - (unsigned long)log_base ||
 704             a + (unsigned long)log_base > ULONG_MAX)
 705                 return false;
 706
 707         return access_ok(log_base + a,
 708                          (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8);
 709 }
 710
 711 static bool vhost_overflow(u64 uaddr, u64 size)
 712 {
 713         /* Make sure 64 bit math will not overflow. */
 714         return uaddr > ULONG_MAX || size > ULONG_MAX || uaddr > ULONG_MAX - size;
 715 }
 716
 717 /* Caller should have vq mutex and device mutex. */
 718 static bool vq_memory_access_ok(void __user *log_base, struct vhost_umem *umem,
 719                                 int log_all)
 720 {
 721         struct vhost_umem_node *node;
 722
 723         if (!umem)
 724                 return false;
 725
 726         list_for_each_entry(node, &umem->umem_list, link) {
 727                 unsigned long a = node->userspace_addr;
 728
 729                 if (vhost_overflow(node->userspace_addr, node->size))
 730                         return false;
 731
 732
 733                 if (!access_ok((void __user *)a,
 734                                     node->size))
 735                         return false;
 736                 else if (log_all && !log_access_ok(log_base,
 737                                                    node->start,
 738                                                    node->size))
 739                         return false;
 740         }
 741         return true;
 742 }
 743
 744 static inline void __user *vhost_vq_meta_fetch(struct vhost_virtqueue *vq,
 745                                                u64 addr, unsigned int size,
 746                                                int type)
 747 {
 748         const struct vhost_umem_node *node = vq->meta_iotlb[type];
 749
 750         if (!node)
 751                 return NULL;
 752
 753         return (void *)(uintptr_t)(node->userspace_addr + addr - node->start);
 754 }
 755
 756 /* Can we switch to this memory table? */
 757 /* Caller should have device mutex but not vq mutex */
 758 static bool memory_access_ok(struct vhost_dev *d, struct vhost_umem *umem,
 759                              int log_all)
 760 {
 761         int i;
 762
 763         for (i = 0; i < d->nvqs; ++i) {
 764                 bool ok;
 765                 bool log;
 766
 767                 mutex_lock(&d->vqs[i]->mutex);
 768                 log = log_all || vhost_has_feature(d->vqs[i], VHOST_F_LOG_ALL);
 769                 /* If ring is inactive, will check when it's enabled. */
 770                 if (d->vqs[i]->private_data)
 771                         ok = vq_memory_access_ok(d->vqs[i]->log_base,
 772                                                  umem, log);
 773                 else
 774                         ok = true;
 775                 mutex_unlock(&d->vqs[i]->mutex);
 776                 if (!ok)
 777                         return false;
 778         }
 779         return true;
 780 }
 781
 782 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
 783                           struct iovec iov[], int iov_size, int access);
 784
 785 static int vhost_copy_to_user(struct vhost_virtqueue *vq, void __user *to,
 786                               const void *from, unsigned size)
 787 {
 788         int ret;
 789
 790         if (!vq->iotlb)
 791                 return __copy_to_user(to, from, size);
 792         else {
 793                 /* This function should be called after iotlb
 794                  * prefetch, which means we're sure that all vq
 795                  * could be access through iotlb. So -EAGAIN should
 796                  * not happen in this case.
 797                  */
 798                 struct iov_iter t;
 799                 void __user *uaddr = vhost_vq_meta_fetch(vq,
 800                                      (u64)(uintptr_t)to, size,
 801                                      VHOST_ADDR_USED);
 802
 803                 if (uaddr)
 804                         return __copy_to_user(uaddr, from, size);
 805
 806                 ret = translate_desc(vq, (u64)(uintptr_t)to, size, vq->iotlb_iov,
 807                                      ARRAY_SIZE(vq->iotlb_iov),
 808                                      VHOST_ACCESS_WO);
 809                 if (ret < 0)
 810                         goto out;
 811                 iov_iter_init(&t, WRITE, vq->iotlb_iov, ret, size);
 812                 ret = copy_to_iter(from, size, &t);
 813                 if (ret == size)
 814                         ret = 0;
 815         }
 816 out:
 817         return ret;
 818 }
 819
 820 static int vhost_copy_from_user(struct vhost_virtqueue *vq, void *to,
 821                                 void __user *from, unsigned size)
 822 {
 823         int ret;
 824
 825         if (!vq->iotlb)
 826                 return __copy_from_user(to, from, size);
 827         else {
 828                 /* This function should be called after iotlb
 829                  * prefetch, which means we're sure that vq
 830                  * could be access through iotlb. So -EAGAIN should
 831                  * not happen in this case.
 832                  */
 833                 void __user *uaddr = vhost_vq_meta_fetch(vq,
 834                                      (u64)(uintptr_t)from, size,
 835                                      VHOST_ADDR_DESC);
 836                 struct iov_iter f;
 837
 838                 if (uaddr)
 839                         return __copy_from_user(to, uaddr, size);
 840
 841                 ret = translate_desc(vq, (u64)(uintptr_t)from, size, vq->iotlb_iov,
 842                                      ARRAY_SIZE(vq->iotlb_iov),
 843                                      VHOST_ACCESS_RO);
 844                 if (ret < 0) {
 845                         vq_err(vq, "IOTLB translation failure: uaddr "
 846                                "%p size 0x%llx\n", from,
 847                                (unsigned long long) size);
 848                         goto out;
 849                 }
 850                 iov_iter_init(&f, READ, vq->iotlb_iov, ret, size);
 851                 ret = copy_from_iter(to, size, &f);
 852                 if (ret == size)
 853                         ret = 0;
 854         }
 855
 856 out:
 857         return ret;
 858 }
 859
 860 static void __user *__vhost_get_user_slow(struct vhost_virtqueue *vq,
 861                                           void __user *addr, unsigned int size,
 862                                           int type)
 863 {
 864         int ret;
 865
 866         ret = translate_desc(vq, (u64)(uintptr_t)addr, 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", addr,
 872                         (unsigned long long) size);
 873                 return NULL;
 874         }
 875
 876         if (ret != 1 || vq->iotlb_iov[0].iov_len != size) {
 877                 vq_err(vq, "Non atomic userspace memory access: uaddr "
 878                         "%p size 0x%llx\n", addr,
 879                         (unsigned long long) size);
 880                 return NULL;
 881         }
 882
 883         return vq->iotlb_iov[0].iov_base;
 884 }
 885
 886 /* This function should be called after iotlb
 887  * prefetch, which means we're sure that vq
 888  * could be access through iotlb. So -EAGAIN should
 889  * not happen in this case.
 890  */
 891 static inline void __user *__vhost_get_user(struct vhost_virtqueue *vq,
 892                                             void *addr, unsigned int size,
 893                                             int type)
 894 {
 895         void __user *uaddr = vhost_vq_meta_fetch(vq,
 896                              (u64)(uintptr_t)addr, size, type);
 897         if (uaddr)
 898                 return uaddr;
 899
 900         return __vhost_get_user_slow(vq, addr, size, type);
 901 }
 902
 903 #define vhost_put_user(vq, x, ptr)              \
 904 ({ \
 905         int ret = -EFAULT; \
 906         if (!vq->iotlb) { \
 907                 ret = __put_user(x, ptr); \
 908         } else { \
 909                 __typeof__(ptr) to = \
 910                         (__typeof__(ptr)) __vhost_get_user(vq, ptr,     \
 911                                           sizeof(*ptr), VHOST_ADDR_USED); \
 912                 if (to != NULL) \
 913                         ret = __put_user(x, to); \
 914                 else \
 915                         ret = -EFAULT;  \
 916         } \
 917         ret; \
 918 })
 919
 920 static inline int vhost_put_avail_event(struct vhost_virtqueue *vq)
 921 {
 922         return vhost_put_user(vq, cpu_to_vhost16(vq, vq->avail_idx),
 923                               vhost_avail_event(vq));
 924 }
 925
 926 static inline int vhost_put_used(struct vhost_virtqueue *vq,
 927                                  struct vring_used_elem *head, int idx,
 928                                  int count)
 929 {
 930         return vhost_copy_to_user(vq, vq->used->ring + idx, head,
 931                                   count * sizeof(*head));
 932 }
 933
 934 static inline int vhost_put_used_flags(struct vhost_virtqueue *vq)
 935
 936 {
 937         return vhost_put_user(vq, cpu_to_vhost16(vq, vq->used_flags),
 938                               &vq->used->flags);
 939 }
 940
 941 static inline int vhost_put_used_idx(struct vhost_virtqueue *vq)
 942
 943 {
 944         return vhost_put_user(vq, cpu_to_vhost16(vq, vq->last_used_idx),
 945                               &vq->used->idx);
 946 }
 947
 948 #define vhost_get_user(vq, x, ptr, type)                \
 949 ({ \
 950         int ret; \
 951         if (!vq->iotlb) { \
 952                 ret = __get_user(x, ptr); \
 953         } else { \
 954                 __typeof__(ptr) from = \
 955                         (__typeof__(ptr)) __vhost_get_user(vq, ptr, \
 956                                                            sizeof(*ptr), \
 957                                                            type); \
 958                 if (from != NULL) \
 959                         ret = __get_user(x, from); \
 960                 else \
 961                         ret = -EFAULT; \
 962         } \
 963         ret; \
 964 })
 965
 966 #define vhost_get_avail(vq, x, ptr) \
 967         vhost_get_user(vq, x, ptr, VHOST_ADDR_AVAIL)
 968
 969 #define vhost_get_used(vq, x, ptr) \
 970         vhost_get_user(vq, x, ptr, VHOST_ADDR_USED)
 971
 972 static void vhost_dev_lock_vqs(struct vhost_dev *d)
 973 {
 974         int i = 0;
 975         for (i = 0; i < d->nvqs; ++i)
 976                 mutex_lock_nested(&d->vqs[i]->mutex, i);
 977 }
 978
 979 static void vhost_dev_unlock_vqs(struct vhost_dev *d)
 980 {
 981         int i = 0;
 982         for (i = 0; i < d->nvqs; ++i)
 983                 mutex_unlock(&d->vqs[i]->mutex);
 984 }
 985
 986 static inline int vhost_get_avail_idx(struct vhost_virtqueue *vq,
 987                                       __virtio16 *idx)
 988 {
 989         return vhost_get_avail(vq, *idx, &vq->avail->idx);
 990 }
 991
 992 static inline int vhost_get_avail_head(struct vhost_virtqueue *vq,
 993                                        __virtio16 *head, int idx)
 994 {
 995         return vhost_get_avail(vq, *head,
 996                                &vq->avail->ring[idx & (vq->num - 1)]);
 997 }
 998
 999 static inline int vhost_get_avail_flags(struct vhost_virtqueue *vq,
1000                                         __virtio16 *flags)
1001 {
1002         return vhost_get_avail(vq, *flags, &vq->avail->flags);
1003 }
1004
1005 static inline int vhost_get_used_event(struct vhost_virtqueue *vq,
1006                                        __virtio16 *event)
1007 {
1008         return vhost_get_avail(vq, *event, vhost_used_event(vq));
1009 }
1010
1011 static inline int vhost_get_used_idx(struct vhost_virtqueue *vq,
1012                                      __virtio16 *idx)
1013 {
1014         return vhost_get_used(vq, *idx, &vq->used->idx);
1015 }
1016
1017 static inline int vhost_get_desc(struct vhost_virtqueue *vq,
1018                                  struct vring_desc *desc, int idx)
1019 {
1020         return vhost_copy_from_user(vq, desc, vq->desc + idx, sizeof(*desc));
1021 }
1022
1023 static int vhost_new_umem_range(struct vhost_umem *umem,
1024                                 u64 start, u64 size, u64 end,
1025                                 u64 userspace_addr, int perm)
1026 {
1027         struct vhost_umem_node *tmp, *node;
1028
1029         if (!size)
1030                 return -EFAULT;
1031
1032         node = kmalloc(sizeof(*node), GFP_ATOMIC);
1033         if (!node)
1034                 return -ENOMEM;
1035
1036         if (umem->numem == max_iotlb_entries) {
1037                 tmp = list_first_entry(&umem->umem_list, typeof(*tmp), link);
1038                 vhost_umem_free(umem, tmp);
1039         }
1040
1041         node->start = start;
1042         node->size = size;
1043         node->last = end;
1044         node->userspace_addr = userspace_addr;
1045         node->perm = perm;
1046         INIT_LIST_HEAD(&node->link);
1047         list_add_tail(&node->link, &umem->umem_list);
1048         vhost_umem_interval_tree_insert(node, &umem->umem_tree);
1049         umem->numem++;
1050
1051         return 0;
1052 }
1053
1054 static void vhost_del_umem_range(struct vhost_umem *umem,
1055                                  u64 start, u64 end)
1056 {
1057         struct vhost_umem_node *node;
1058
1059         while ((node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
1060                                                            start, end)))
1061                 vhost_umem_free(umem, node);
1062 }
1063
1064 static void vhost_iotlb_notify_vq(struct vhost_dev *d,
1065                                   struct vhost_iotlb_msg *msg)
1066 {
1067         struct vhost_msg_node *node, *n;
1068
1069         spin_lock(&d->iotlb_lock);
1070
1071         list_for_each_entry_safe(node, n, &d->pending_list, node) {
1072                 struct vhost_iotlb_msg *vq_msg = &node->msg.iotlb;
1073                 if (msg->iova <= vq_msg->iova &&
1074                     msg->iova + msg->size - 1 >= vq_msg->iova &&
1075                     vq_msg->type == VHOST_IOTLB_MISS) {
1076                         vhost_poll_queue(&node->vq->poll);
1077                         list_del(&node->node);
1078                         kfree(node);
1079                 }
1080         }
1081
1082         spin_unlock(&d->iotlb_lock);
1083 }
1084
1085 static bool umem_access_ok(u64 uaddr, u64 size, int access)
1086 {
1087         unsigned long a = uaddr;
1088
1089         /* Make sure 64 bit math will not overflow. */
1090         if (vhost_overflow(uaddr, size))
1091                 return false;
1092
1093         if ((access & VHOST_ACCESS_RO) &&
1094             !access_ok((void __user *)a, size))
1095                 return false;
1096         if ((access & VHOST_ACCESS_WO) &&
1097             !access_ok((void __user *)a, size))
1098                 return false;
1099         return true;
1100 }
1101
1102 static int vhost_process_iotlb_msg(struct vhost_dev *dev,
1103                                    struct vhost_iotlb_msg *msg)
1104 {
1105         int ret = 0;
1106
1107         mutex_lock(&dev->mutex);
1108         vhost_dev_lock_vqs(dev);
1109         switch (msg->type) {
1110         case VHOST_IOTLB_UPDATE:
1111                 if (!dev->iotlb) {
1112                         ret = -EFAULT;
1113                         break;
1114                 }
1115                 if (!umem_access_ok(msg->uaddr, msg->size, msg->perm)) {
1116                         ret = -EFAULT;
1117                         break;
1118                 }
1119                 vhost_vq_meta_reset(dev);
1120                 if (vhost_new_umem_range(dev->iotlb, msg->iova, msg->size,
1121                                          msg->iova + msg->size - 1,
1122                                          msg->uaddr, msg->perm)) {
1123                         ret = -ENOMEM;
1124                         break;
1125                 }
1126                 vhost_iotlb_notify_vq(dev, msg);
1127                 break;
1128         case VHOST_IOTLB_INVALIDATE:
1129                 if (!dev->iotlb) {
1130                         ret = -EFAULT;
1131                         break;
1132                 }
1133                 vhost_vq_meta_reset(dev);
1134                 vhost_del_umem_range(dev->iotlb, msg->iova,
1135                                      msg->iova + msg->size - 1);
1136                 break;
1137         default:
1138                 ret = -EINVAL;
1139                 break;
1140         }
1141
1142         vhost_dev_unlock_vqs(dev);
1143         mutex_unlock(&dev->mutex);
1144
1145         return ret;
1146 }
1147 ssize_t vhost_chr_write_iter(struct vhost_dev *dev,
1148                              struct iov_iter *from)
1149 {
1150         struct vhost_iotlb_msg msg;
1151         size_t offset;
1152         int type, ret;
1153
1154         ret = copy_from_iter(&type, sizeof(type), from);
1155         if (ret != sizeof(type)) {
1156                 ret = -EINVAL;
1157                 goto done;
1158         }
1159
1160         switch (type) {
1161         case VHOST_IOTLB_MSG:
1162                 /* There maybe a hole after type for V1 message type,
1163                  * so skip it here.
1164                  */
1165                 offset = offsetof(struct vhost_msg, iotlb) - sizeof(int);
1166                 break;
1167         case VHOST_IOTLB_MSG_V2:
1168                 offset = sizeof(__u32);
1169                 break;
1170         default:
1171                 ret = -EINVAL;
1172                 goto done;
1173         }
1174
1175         iov_iter_advance(from, offset);
1176         ret = copy_from_iter(&msg, sizeof(msg), from);
1177         if (ret != sizeof(msg)) {
1178                 ret = -EINVAL;
1179                 goto done;
1180         }
1181         if (vhost_process_iotlb_msg(dev, &msg)) {
1182                 ret = -EFAULT;
1183                 goto done;
1184         }
1185
1186         ret = (type == VHOST_IOTLB_MSG) ? sizeof(struct vhost_msg) :
1187               sizeof(struct vhost_msg_v2);
1188 done:
1189         return ret;
1190 }
1191 EXPORT_SYMBOL(vhost_chr_write_iter);
1192
1193 __poll_t vhost_chr_poll(struct file *file, struct vhost_dev *dev,
1194                             poll_table *wait)
1195 {
1196         __poll_t mask = 0;
1197
1198         poll_wait(file, &dev->wait, wait);
1199
1200         if (!list_empty(&dev->read_list))
1201                 mask |= EPOLLIN | EPOLLRDNORM;
1202
1203         return mask;
1204 }
1205 EXPORT_SYMBOL(vhost_chr_poll);
1206
1207 ssize_t vhost_chr_read_iter(struct vhost_dev *dev, struct iov_iter *to,
1208                             int noblock)
1209 {
1210         DEFINE_WAIT(wait);
1211         struct vhost_msg_node *node;
1212         ssize_t ret = 0;
1213         unsigned size = sizeof(struct vhost_msg);
1214
1215         if (iov_iter_count(to) < size)
1216                 return 0;
1217
1218         while (1) {
1219                 if (!noblock)
1220                         prepare_to_wait(&dev->wait, &wait,
1221                                         TASK_INTERRUPTIBLE);
1222
1223                 node = vhost_dequeue_msg(dev, &dev->read_list);
1224                 if (node)
1225                         break;
1226                 if (noblock) {
1227                         ret = -EAGAIN;
1228                         break;
1229                 }
1230                 if (signal_pending(current)) {
1231                         ret = -ERESTARTSYS;
1232                         break;
1233                 }
1234                 if (!dev->iotlb) {
1235                         ret = -EBADFD;
1236                         break;
1237                 }
1238
1239                 schedule();
1240         }
1241
1242         if (!noblock)
1243                 finish_wait(&dev->wait, &wait);
1244
1245         if (node) {
1246                 struct vhost_iotlb_msg *msg;
1247                 void *start = &node->msg;
1248
1249                 switch (node->msg.type) {
1250                 case VHOST_IOTLB_MSG:
1251                         size = sizeof(node->msg);
1252                         msg = &node->msg.iotlb;
1253                         break;
1254                 case VHOST_IOTLB_MSG_V2:
1255                         size = sizeof(node->msg_v2);
1256                         msg = &node->msg_v2.iotlb;
1257                         break;
1258                 default:
1259                         BUG();
1260                         break;
1261                 }
1262
1263                 ret = copy_to_iter(start, size, to);
1264                 if (ret != size || msg->type != VHOST_IOTLB_MISS) {
1265                         kfree(node);
1266                         return ret;
1267                 }
1268                 vhost_enqueue_msg(dev, &dev->pending_list, node);
1269         }
1270
1271         return ret;
1272 }
1273 EXPORT_SYMBOL_GPL(vhost_chr_read_iter);
1274
1275 static int vhost_iotlb_miss(struct vhost_virtqueue *vq, u64 iova, int access)
1276 {
1277         struct vhost_dev *dev = vq->dev;
1278         struct vhost_msg_node *node;
1279         struct vhost_iotlb_msg *msg;
1280         bool v2 = vhost_backend_has_feature(vq, VHOST_BACKEND_F_IOTLB_MSG_V2);
1281
1282         node = vhost_new_msg(vq, v2 ? VHOST_IOTLB_MSG_V2 : VHOST_IOTLB_MSG);
1283         if (!node)
1284                 return -ENOMEM;
1285
1286         if (v2) {
1287                 node->msg_v2.type = VHOST_IOTLB_MSG_V2;
1288                 msg = &node->msg_v2.iotlb;
1289         } else {
1290                 msg = &node->msg.iotlb;
1291         }
1292
1293         msg->type = VHOST_IOTLB_MISS;
1294         msg->iova = iova;
1295         msg->perm = access;
1296
1297         vhost_enqueue_msg(dev, &dev->read_list, node);
1298
1299         return 0;
1300 }
1301
1302 static bool vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
1303                          struct vring_desc __user *desc,
1304                          struct vring_avail __user *avail,
1305                          struct vring_used __user *used)
1306
1307 {
1308         return access_ok(desc, vhost_get_desc_size(vq, num)) &&
1309                access_ok(avail, vhost_get_avail_size(vq, num)) &&
1310                access_ok(used, vhost_get_used_size(vq, num));
1311 }
1312
1313 static void vhost_vq_meta_update(struct vhost_virtqueue *vq,
1314                                  const struct vhost_umem_node *node,
1315                                  int type)
1316 {
1317         int access = (type == VHOST_ADDR_USED) ?
1318                      VHOST_ACCESS_WO : VHOST_ACCESS_RO;
1319
1320         if (likely(node->perm & access))
1321                 vq->meta_iotlb[type] = node;
1322 }
1323
1324 static bool iotlb_access_ok(struct vhost_virtqueue *vq,
1325                             int access, u64 addr, u64 len, int type)
1326 {
1327         const struct vhost_umem_node *node;
1328         struct vhost_umem *umem = vq->iotlb;
1329         u64 s = 0, size, orig_addr = addr, last = addr + len - 1;
1330
1331         if (vhost_vq_meta_fetch(vq, addr, len, type))
1332                 return true;
1333
1334         while (len > s) {
1335                 node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
1336                                                            addr,
1337                                                            last);
1338                 if (node == NULL || node->start > addr) {
1339                         vhost_iotlb_miss(vq, addr, access);
1340                         return false;
1341                 } else if (!(node->perm & access)) {
1342                         /* Report the possible access violation by
1343                          * request another translation from userspace.
1344                          */
1345                         return false;
1346                 }
1347
1348                 size = node->size - addr + node->start;
1349
1350                 if (orig_addr == addr && size >= len)
1351                         vhost_vq_meta_update(vq, node, type);
1352
1353                 s += size;
1354                 addr += size;
1355         }
1356
1357         return true;
1358 }
1359
1360 int vq_meta_prefetch(struct vhost_virtqueue *vq)
1361 {
1362         unsigned int num = vq->num;
1363
1364         if (!vq->iotlb)
1365                 return 1;
1366
1367         return iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->desc,
1368                                vhost_get_desc_size(vq, num), VHOST_ADDR_DESC) &&
1369                iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->avail,
1370                                vhost_get_avail_size(vq, num),
1371                                VHOST_ADDR_AVAIL) &&
1372                iotlb_access_ok(vq, VHOST_ACCESS_WO, (u64)(uintptr_t)vq->used,
1373                                vhost_get_used_size(vq, num), VHOST_ADDR_USED);
1374 }
1375 EXPORT_SYMBOL_GPL(vq_meta_prefetch);
1376
1377 /* Can we log writes? */
1378 /* Caller should have device mutex but not vq mutex */
1379 bool vhost_log_access_ok(struct vhost_dev *dev)
1380 {
1381         return memory_access_ok(dev, dev->umem, 1);
1382 }
1383 EXPORT_SYMBOL_GPL(vhost_log_access_ok);
1384
1385 /* Verify access for write logging. */
1386 /* Caller should have vq mutex and device mutex */
1387 static bool vq_log_access_ok(struct vhost_virtqueue *vq,
1388                              void __user *log_base)
1389 {
1390         return vq_memory_access_ok(log_base, vq->umem,
1391                                    vhost_has_feature(vq, VHOST_F_LOG_ALL)) &&
1392                 (!vq->log_used || log_access_ok(log_base, vq->log_addr,
1393                                   vhost_get_used_size(vq, vq->num)));
1394 }
1395
1396 /* Can we start vq? */
1397 /* Caller should have vq mutex and device mutex */
1398 bool vhost_vq_access_ok(struct vhost_virtqueue *vq)
1399 {
1400         if (!vq_log_access_ok(vq, vq->log_base))
1401                 return false;
1402
1403         /* Access validation occurs at prefetch time with IOTLB */
1404         if (vq->iotlb)
1405                 return true;
1406
1407         return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used);
1408 }
1409 EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
1410
1411 static struct vhost_umem *vhost_umem_alloc(void)
1412 {
1413         struct vhost_umem *umem = kvzalloc(sizeof(*umem), GFP_KERNEL);
1414
1415         if (!umem)
1416                 return NULL;
1417
1418         umem->umem_tree = RB_ROOT_CACHED;
1419         umem->numem = 0;
1420         INIT_LIST_HEAD(&umem->umem_list);
1421
1422         return umem;
1423 }
1424
1425 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
1426 {
1427         struct vhost_memory mem, *newmem;
1428         struct vhost_memory_region *region;
1429         struct vhost_umem *newumem, *oldumem;
1430         unsigned long size = offsetof(struct vhost_memory, regions);
1431         int i;
1432
1433         if (copy_from_user(&mem, m, size))
1434                 return -EFAULT;
1435         if (mem.padding)
1436                 return -EOPNOTSUPP;
1437         if (mem.nregions > max_mem_regions)
1438                 return -E2BIG;
1439         newmem = kvzalloc(struct_size(newmem, regions, mem.nregions),
1440                         GFP_KERNEL);
1441         if (!newmem)
1442                 return -ENOMEM;
1443
1444         memcpy(newmem, &mem, size);
1445         if (copy_from_user(newmem->regions, m->regions,
1446                            mem.nregions * sizeof *m->regions)) {
1447                 kvfree(newmem);
1448                 return -EFAULT;
1449         }
1450
1451         newumem = vhost_umem_alloc();
1452         if (!newumem) {
1453                 kvfree(newmem);
1454                 return -ENOMEM;
1455         }
1456
1457         for (region = newmem->regions;
1458              region < newmem->regions + mem.nregions;
1459              region++) {
1460                 if (vhost_new_umem_range(newumem,
1461                                          region->guest_phys_addr,
1462                                          region->memory_size,
1463                                          region->guest_phys_addr +
1464                                          region->memory_size - 1,
1465                                          region->userspace_addr,
1466                                          VHOST_ACCESS_RW))
1467                         goto err;
1468         }
1469
1470         if (!memory_access_ok(d, newumem, 0))
1471                 goto err;
1472
1473         oldumem = d->umem;
1474         d->umem = newumem;
1475
1476         /* All memory accesses are done under some VQ mutex. */
1477         for (i = 0; i < d->nvqs; ++i) {
1478                 mutex_lock(&d->vqs[i]->mutex);
1479                 d->vqs[i]->umem = newumem;
1480                 mutex_unlock(&d->vqs[i]->mutex);
1481         }
1482
1483         kvfree(newmem);
1484         vhost_umem_clean(oldumem);
1485         return 0;
1486
1487 err:
1488         vhost_umem_clean(newumem);
1489         kvfree(newmem);
1490         return -EFAULT;
1491 }
1492
1493 static long vhost_vring_set_num(struct vhost_dev *d,
1494                                 struct vhost_virtqueue *vq,
1495                                 void __user *argp)
1496 {
1497         struct vhost_vring_state s;
1498
1499         /* Resizing ring with an active backend?
1500          * You don't want to do that. */
1501         if (vq->private_data)
1502                 return -EBUSY;
1503
1504         if (copy_from_user(&s, argp, sizeof s))
1505                 return -EFAULT;
1506
1507         if (!s.num || s.num > 0xffff || (s.num & (s.num - 1)))
1508                 return -EINVAL;
1509         vq->num = s.num;
1510
1511         return 0;
1512 }
1513
1514 static long vhost_vring_set_addr(struct vhost_dev *d,
1515                                  struct vhost_virtqueue *vq,
1516                                  void __user *argp)
1517 {
1518         struct vhost_vring_addr a;
1519
1520         if (copy_from_user(&a, argp, sizeof a))
1521                 return -EFAULT;
1522         if (a.flags & ~(0x1 << VHOST_VRING_F_LOG))
1523                 return -EOPNOTSUPP;
1524
1525         /* For 32bit, verify that the top 32bits of the user
1526            data are set to zero. */
1527         if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr ||
1528             (u64)(unsigned long)a.used_user_addr != a.used_user_addr ||
1529             (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr)
1530                 return -EFAULT;
1531
1532         /* Make sure it's safe to cast pointers to vring types. */
1533         BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE);
1534         BUILD_BUG_ON(__alignof__ *vq->used > VRING_USED_ALIGN_SIZE);
1535         if ((a.avail_user_addr & (VRING_AVAIL_ALIGN_SIZE - 1)) ||
1536             (a.used_user_addr & (VRING_USED_ALIGN_SIZE - 1)) ||
1537             (a.log_guest_addr & (VRING_USED_ALIGN_SIZE - 1)))
1538                 return -EINVAL;
1539
1540         /* We only verify access here if backend is configured.
1541          * If it is not, we don't as size might not have been setup.
1542          * We will verify when backend is configured. */
1543         if (vq->private_data) {
1544                 if (!vq_access_ok(vq, vq->num,
1545                         (void __user *)(unsigned long)a.desc_user_addr,
1546                         (void __user *)(unsigned long)a.avail_user_addr,
1547                         (void __user *)(unsigned long)a.used_user_addr))
1548                         return -EINVAL;
1549
1550                 /* Also validate log access for used ring if enabled. */
1551                 if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) &&
1552                         !log_access_ok(vq->log_base, a.log_guest_addr,
1553                                 sizeof *vq->used +
1554                                 vq->num * sizeof *vq->used->ring))
1555                         return -EINVAL;
1556         }
1557
1558         vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
1559         vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
1560         vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
1561         vq->log_addr = a.log_guest_addr;
1562         vq->used = (void __user *)(unsigned long)a.used_user_addr;
1563
1564         return 0;
1565 }
1566
1567 static long vhost_vring_set_num_addr(struct vhost_dev *d,
1568                                      struct vhost_virtqueue *vq,
1569                                      unsigned int ioctl,
1570                                      void __user *argp)
1571 {
1572         long r;
1573
1574         mutex_lock(&vq->mutex);
1575
1576         switch (ioctl) {
1577         case VHOST_SET_VRING_NUM:
1578                 r = vhost_vring_set_num(d, vq, argp);
1579                 break;
1580         case VHOST_SET_VRING_ADDR:
1581                 r = vhost_vring_set_addr(d, vq, argp);
1582                 break;
1583         default:
1584                 BUG();
1585         }
1586
1587         mutex_unlock(&vq->mutex);
1588
1589         return r;
1590 }
1591 long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
1592 {
1593         struct file *eventfp, *filep = NULL;
1594         bool pollstart = false, pollstop = false;
1595         struct eventfd_ctx *ctx = NULL;
1596         u32 __user *idxp = argp;
1597         struct vhost_virtqueue *vq;
1598         struct vhost_vring_state s;
1599         struct vhost_vring_file f;
1600         u32 idx;
1601         long r;
1602
1603         r = get_user(idx, idxp);
1604         if (r < 0)
1605                 return r;
1606         if (idx >= d->nvqs)
1607                 return -ENOBUFS;
1608
1609         idx = array_index_nospec(idx, d->nvqs);
1610         vq = d->vqs[idx];
1611
1612         if (ioctl == VHOST_SET_VRING_NUM ||
1613             ioctl == VHOST_SET_VRING_ADDR) {
1614                 return vhost_vring_set_num_addr(d, vq, ioctl, argp);
1615         }
1616
1617         mutex_lock(&vq->mutex);
1618
1619         switch (ioctl) {
1620         case VHOST_SET_VRING_BASE:
1621                 /* Moving base with an active backend?
1622                  * You don't want to do that. */
1623                 if (vq->private_data) {
1624                         r = -EBUSY;
1625                         break;
1626                 }
1627                 if (copy_from_user(&s, argp, sizeof s)) {
1628                         r = -EFAULT;
1629                         break;
1630                 }
1631                 if (s.num > 0xffff) {
1632                         r = -EINVAL;
1633                         break;
1634                 }
1635                 vq->last_avail_idx = s.num;
1636                 /* Forget the cached index value. */
1637                 vq->avail_idx = vq->last_avail_idx;
1638                 break;
1639         case VHOST_GET_VRING_BASE:
1640                 s.index = idx;
1641                 s.num = vq->last_avail_idx;
1642                 if (copy_to_user(argp, &s, sizeof s))
1643                         r = -EFAULT;
1644                 break;
1645         case VHOST_SET_VRING_KICK:
1646                 if (copy_from_user(&f, argp, sizeof f)) {
1647                         r = -EFAULT;
1648                         break;
1649                 }
1650                 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
1651                 if (IS_ERR(eventfp)) {
1652                         r = PTR_ERR(eventfp);
1653                         break;
1654                 }
1655                 if (eventfp != vq->kick) {
1656                         pollstop = (filep = vq->kick) != NULL;
1657                         pollstart = (vq->kick = eventfp) != NULL;
1658                 } else
1659                         filep = eventfp;
1660                 break;
1661         case VHOST_SET_VRING_CALL:
1662                 if (copy_from_user(&f, argp, sizeof f)) {
1663                         r = -EFAULT;
1664                         break;
1665                 }
1666                 ctx = f.fd == -1 ? NULL : eventfd_ctx_fdget(f.fd);
1667                 if (IS_ERR(ctx)) {
1668                         r = PTR_ERR(ctx);
1669                         break;
1670                 }
1671                 swap(ctx, vq->call_ctx);
1672                 break;
1673         case VHOST_SET_VRING_ERR:
1674                 if (copy_from_user(&f, argp, sizeof f)) {
1675                         r = -EFAULT;
1676                         break;
1677                 }
1678                 ctx = f.fd == -1 ? NULL : eventfd_ctx_fdget(f.fd);
1679                 if (IS_ERR(ctx)) {
1680                         r = PTR_ERR(ctx);
1681                         break;
1682                 }
1683                 swap(ctx, vq->error_ctx);
1684                 break;
1685         case VHOST_SET_VRING_ENDIAN:
1686                 r = vhost_set_vring_endian(vq, argp);
1687                 break;
1688         case VHOST_GET_VRING_ENDIAN:
1689                 r = vhost_get_vring_endian(vq, idx, argp);
1690                 break;
1691         case VHOST_SET_VRING_BUSYLOOP_TIMEOUT:
1692                 if (copy_from_user(&s, argp, sizeof(s))) {
1693                         r = -EFAULT;
1694                         break;
1695                 }
1696                 vq->busyloop_timeout = s.num;
1697                 break;
1698         case VHOST_GET_VRING_BUSYLOOP_TIMEOUT:
1699                 s.index = idx;
1700                 s.num = vq->busyloop_timeout;
1701                 if (copy_to_user(argp, &s, sizeof(s)))
1702                         r = -EFAULT;
1703                 break;
1704         default:
1705                 r = -ENOIOCTLCMD;
1706         }
1707
1708         if (pollstop && vq->handle_kick)
1709                 vhost_poll_stop(&vq->poll);
1710
1711         if (!IS_ERR_OR_NULL(ctx))
1712                 eventfd_ctx_put(ctx);
1713         if (filep)
1714                 fput(filep);
1715
1716         if (pollstart && vq->handle_kick)
1717                 r = vhost_poll_start(&vq->poll, vq->kick);
1718
1719         mutex_unlock(&vq->mutex);
1720
1721         if (pollstop && vq->handle_kick)
1722                 vhost_poll_flush(&vq->poll);
1723         return r;
1724 }
1725 EXPORT_SYMBOL_GPL(vhost_vring_ioctl);
1726
1727 int vhost_init_device_iotlb(struct vhost_dev *d, bool enabled)
1728 {
1729         struct vhost_umem *niotlb, *oiotlb;
1730         int i;
1731
1732         niotlb = vhost_umem_alloc();
1733         if (!niotlb)
1734                 return -ENOMEM;
1735
1736         oiotlb = d->iotlb;
1737         d->iotlb = niotlb;
1738
1739         for (i = 0; i < d->nvqs; ++i) {
1740                 struct vhost_virtqueue *vq = d->vqs[i];
1741
1742                 mutex_lock(&vq->mutex);
1743                 vq->iotlb = niotlb;
1744                 __vhost_vq_meta_reset(vq);
1745                 mutex_unlock(&vq->mutex);
1746         }
1747
1748         vhost_umem_clean(oiotlb);
1749
1750         return 0;
1751 }
1752 EXPORT_SYMBOL_GPL(vhost_init_device_iotlb);
1753
1754 /* Caller must have device mutex */
1755 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
1756 {
1757         struct eventfd_ctx *ctx;
1758         u64 p;
1759         long r;
1760         int i, fd;
1761
1762         /* If you are not the owner, you can become one */
1763         if (ioctl == VHOST_SET_OWNER) {
1764                 r = vhost_dev_set_owner(d);
1765                 goto done;
1766         }
1767
1768         /* You must be the owner to do anything else */
1769         r = vhost_dev_check_owner(d);
1770         if (r)
1771                 goto done;
1772
1773         switch (ioctl) {
1774         case VHOST_SET_MEM_TABLE:
1775                 r = vhost_set_memory(d, argp);
1776                 break;
1777         case VHOST_SET_LOG_BASE:
1778                 if (copy_from_user(&p, argp, sizeof p)) {
1779                         r = -EFAULT;
1780                         break;
1781                 }
1782                 if ((u64)(unsigned long)p != p) {
1783                         r = -EFAULT;
1784                         break;
1785                 }
1786                 for (i = 0; i < d->nvqs; ++i) {
1787                         struct vhost_virtqueue *vq;
1788                         void __user *base = (void __user *)(unsigned long)p;
1789                         vq = d->vqs[i];
1790                         mutex_lock(&vq->mutex);
1791                         /* If ring is inactive, will check when it's enabled. */
1792                         if (vq->private_data && !vq_log_access_ok(vq, base))
1793                                 r = -EFAULT;
1794                         else
1795                                 vq->log_base = base;
1796                         mutex_unlock(&vq->mutex);
1797                 }
1798                 break;
1799         case VHOST_SET_LOG_FD:
1800                 r = get_user(fd, (int __user *)argp);
1801                 if (r < 0)
1802                         break;
1803                 ctx = fd == -1 ? NULL : eventfd_ctx_fdget(fd);
1804                 if (IS_ERR(ctx)) {
1805                         r = PTR_ERR(ctx);
1806                         break;
1807                 }
1808                 swap(ctx, d->log_ctx);
1809                 for (i = 0; i < d->nvqs; ++i) {
1810                         mutex_lock(&d->vqs[i]->mutex);
1811                         d->vqs[i]->log_ctx = d->log_ctx;
1812                         mutex_unlock(&d->vqs[i]->mutex);
1813                 }
1814                 if (ctx)
1815                         eventfd_ctx_put(ctx);
1816                 break;
1817         default:
1818                 r = -ENOIOCTLCMD;
1819                 break;
1820         }
1821 done:
1822         return r;
1823 }
1824 EXPORT_SYMBOL_GPL(vhost_dev_ioctl);
1825
1826 /* TODO: This is really inefficient.  We need something like get_user()
1827  * (instruction directly accesses the data, with an exception table entry
1828  * returning -EFAULT). See Documentation/x86/exception-tables.rst.
1829  */
1830 static int set_bit_to_user(int nr, void __user *addr)
1831 {
1832         unsigned long log = (unsigned long)addr;
1833         struct page *page;
1834         void *base;
1835         int bit = nr + (log % PAGE_SIZE) * 8;
1836         int r;
1837
1838         r = get_user_pages_fast(log, 1, FOLL_WRITE, &page);
1839         if (r < 0)
1840                 return r;
1841         BUG_ON(r != 1);
1842         base = kmap_atomic(page);
1843         set_bit(bit, base);
1844         kunmap_atomic(base);
1845         set_page_dirty_lock(page);
1846         put_page(page);
1847         return 0;
1848 }
1849
1850 static int log_write(void __user *log_base,
1851                      u64 write_address, u64 write_length)
1852 {
1853         u64 write_page = write_address / VHOST_PAGE_SIZE;
1854         int r;
1855
1856         if (!write_length)
1857                 return 0;
1858         write_length += write_address % VHOST_PAGE_SIZE;
1859         for (;;) {
1860                 u64 base = (u64)(unsigned long)log_base;
1861                 u64 log = base + write_page / 8;
1862                 int bit = write_page % 8;
1863                 if ((u64)(unsigned long)log != log)
1864                         return -EFAULT;
1865                 r = set_bit_to_user(bit, (void __user *)(unsigned long)log);
1866                 if (r < 0)
1867                         return r;
1868                 if (write_length <= VHOST_PAGE_SIZE)
1869                         break;
1870                 write_length -= VHOST_PAGE_SIZE;
1871                 write_page += 1;
1872         }
1873         return r;
1874 }
1875
1876 static int log_write_hva(struct vhost_virtqueue *vq, u64 hva, u64 len)
1877 {
1878         struct vhost_umem *umem = vq->umem;
1879         struct vhost_umem_node *u;
1880         u64 start, end, l, min;
1881         int r;
1882         bool hit = false;
1883
1884         while (len) {
1885                 min = len;
1886                 /* More than one GPAs can be mapped into a single HVA. So
1887                  * iterate all possible umems here to be safe.
1888                  */
1889                 list_for_each_entry(u, &umem->umem_list, link) {
1890                         if (u->userspace_addr > hva - 1 + len ||
1891                             u->userspace_addr - 1 + u->size < hva)
1892                                 continue;
1893                         start = max(u->userspace_addr, hva);
1894                         end = min(u->userspace_addr - 1 + u->size,
1895                                   hva - 1 + len);
1896                         l = end - start + 1;
1897                         r = log_write(vq->log_base,
1898                                       u->start + start - u->userspace_addr,
1899                                       l);
1900                         if (r < 0)
1901                                 return r;
1902                         hit = true;
1903                         min = min(l, min);
1904                 }
1905
1906                 if (!hit)
1907                         return -EFAULT;
1908
1909                 len -= min;
1910                 hva += min;
1911         }
1912
1913         return 0;
1914 }
1915
1916 static int log_used(struct vhost_virtqueue *vq, u64 used_offset, u64 len)
1917 {
1918         struct iovec iov[64];
1919         int i, ret;
1920
1921         if (!vq->iotlb)
1922                 return log_write(vq->log_base, vq->log_addr + used_offset, len);
1923
1924         ret = translate_desc(vq, (uintptr_t)vq->used + used_offset,
1925                              len, iov, 64, VHOST_ACCESS_WO);
1926         if (ret < 0)
1927                 return ret;
1928
1929         for (i = 0; i < ret; i++) {
1930                 ret = log_write_hva(vq, (uintptr_t)iov[i].iov_base,
1931                                     iov[i].iov_len);
1932                 if (ret)
1933                         return ret;
1934         }
1935
1936         return 0;
1937 }
1938
1939 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
1940                     unsigned int log_num, u64 len, struct iovec *iov, int count)
1941 {
1942         int i, r;
1943
1944         /* Make sure data written is seen before log. */
1945         smp_wmb();
1946
1947         if (vq->iotlb) {
1948                 for (i = 0; i < count; i++) {
1949                         r = log_write_hva(vq, (uintptr_t)iov[i].iov_base,
1950                                           iov[i].iov_len);
1951                         if (r < 0)
1952                                 return r;
1953                 }
1954                 return 0;
1955         }
1956
1957         for (i = 0; i < log_num; ++i) {
1958                 u64 l = min(log[i].len, len);
1959                 r = log_write(vq->log_base, log[i].addr, l);
1960                 if (r < 0)
1961                         return r;
1962                 len -= l;
1963                 if (!len) {
1964                         if (vq->log_ctx)
1965                                 eventfd_signal(vq->log_ctx, 1);
1966                         return 0;
1967                 }
1968         }
1969         /* Length written exceeds what we have stored. This is a bug. */
1970         BUG();
1971         return 0;
1972 }
1973 EXPORT_SYMBOL_GPL(vhost_log_write);
1974
1975 static int vhost_update_used_flags(struct vhost_virtqueue *vq)
1976 {
1977         void __user *used;
1978         if (vhost_put_used_flags(vq))
1979                 return -EFAULT;
1980         if (unlikely(vq->log_used)) {
1981                 /* Make sure the flag is seen before log. */
1982                 smp_wmb();
1983                 /* Log used flag write. */
1984                 used = &vq->used->flags;
1985                 log_used(vq, (used - (void __user *)vq->used),
1986                          sizeof vq->used->flags);
1987                 if (vq->log_ctx)
1988                         eventfd_signal(vq->log_ctx, 1);
1989         }
1990         return 0;
1991 }
1992
1993 static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event)
1994 {
1995         if (vhost_put_avail_event(vq))
1996                 return -EFAULT;
1997         if (unlikely(vq->log_used)) {
1998                 void __user *used;
1999                 /* Make sure the event is seen before log. */
2000                 smp_wmb();
2001                 /* Log avail event write */
2002                 used = vhost_avail_event(vq);
2003                 log_used(vq, (used - (void __user *)vq->used),
2004                          sizeof *vhost_avail_event(vq));
2005                 if (vq->log_ctx)
2006                         eventfd_signal(vq->log_ctx, 1);
2007         }
2008         return 0;
2009 }
2010
2011 int vhost_vq_init_access(struct vhost_virtqueue *vq)
2012 {
2013         __virtio16 last_used_idx;
2014         int r;
2015         bool is_le = vq->is_le;
2016
2017         if (!vq->private_data)
2018                 return 0;
2019
2020         vhost_init_is_le(vq);
2021
2022         r = vhost_update_used_flags(vq);
2023         if (r)
2024                 goto err;
2025         vq->signalled_used_valid = false;
2026         if (!vq->iotlb &&
2027             !access_ok(&vq->used->idx, sizeof vq->used->idx)) {
2028                 r = -EFAULT;
2029                 goto err;
2030         }
2031         r = vhost_get_used_idx(vq, &last_used_idx);
2032         if (r) {
2033                 vq_err(vq, "Can't access used idx at %p\n",
2034                        &vq->used->idx);
2035                 goto err;
2036         }
2037         vq->last_used_idx = vhost16_to_cpu(vq, last_used_idx);
2038         return 0;
2039
2040 err:
2041         vq->is_le = is_le;
2042         return r;
2043 }
2044 EXPORT_SYMBOL_GPL(vhost_vq_init_access);
2045
2046 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
2047                           struct iovec iov[], int iov_size, int access)
2048 {
2049         const struct vhost_umem_node *node;
2050         struct vhost_dev *dev = vq->dev;
2051         struct vhost_umem *umem = dev->iotlb ? dev->iotlb : dev->umem;
2052         struct iovec *_iov;
2053         u64 s = 0;
2054         int ret = 0;
2055
2056         while ((u64)len > s) {
2057                 u64 size;
2058                 if (unlikely(ret >= iov_size)) {
2059                         ret = -ENOBUFS;
2060                         break;
2061                 }
2062
2063                 node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
2064                                                         addr, addr + len - 1);
2065                 if (node == NULL || node->start > addr) {
2066                         if (umem != dev->iotlb) {
2067                                 ret = -EFAULT;
2068                                 break;
2069                         }
2070                         ret = -EAGAIN;
2071                         break;
2072                 } else if (!(node->perm & access)) {
2073                         ret = -EPERM;
2074                         break;
2075                 }
2076
2077                 _iov = iov + ret;
2078                 size = node->size - addr + node->start;
2079                 _iov->iov_len = min((u64)len - s, size);
2080                 _iov->iov_base = (void __user *)(unsigned long)
2081                         (node->userspace_addr + addr - node->start);
2082                 s += size;
2083                 addr += size;
2084                 ++ret;
2085         }
2086
2087         if (ret == -EAGAIN)
2088                 vhost_iotlb_miss(vq, addr, access);
2089         return ret;
2090 }
2091
2092 /* Each buffer in the virtqueues is actually a chain of descriptors.  This
2093  * function returns the next descriptor in the chain,
2094  * or -1U if we're at the end. */
2095 static unsigned next_desc(struct vhost_virtqueue *vq, struct vring_desc *desc)
2096 {
2097         unsigned int next;
2098
2099         /* If this descriptor says it doesn't chain, we're done. */
2100         if (!(desc->flags & cpu_to_vhost16(vq, VRING_DESC_F_NEXT)))
2101                 return -1U;
2102
2103         /* Check they're not leading us off end of descriptors. */
2104         next = vhost16_to_cpu(vq, READ_ONCE(desc->next));
2105         return next;
2106 }
2107
2108 static int get_indirect(struct vhost_virtqueue *vq,
2109                         struct iovec iov[], unsigned int iov_size,
2110                         unsigned int *out_num, unsigned int *in_num,
2111                         struct vhost_log *log, unsigned int *log_num,
2112                         struct vring_desc *indirect)
2113 {
2114         struct vring_desc desc;
2115         unsigned int i = 0, count, found = 0;
2116         u32 len = vhost32_to_cpu(vq, indirect->len);
2117         struct iov_iter from;
2118         int ret, access;
2119
2120         /* Sanity check */
2121         if (unlikely(len % sizeof desc)) {
2122                 vq_err(vq, "Invalid length in indirect descriptor: "
2123                        "len 0x%llx not multiple of 0x%zx\n",
2124                        (unsigned long long)len,
2125                        sizeof desc);
2126                 return -EINVAL;
2127         }
2128
2129         ret = translate_desc(vq, vhost64_to_cpu(vq, indirect->addr), len, vq->indirect,
2130                              UIO_MAXIOV, VHOST_ACCESS_RO);
2131         if (unlikely(ret < 0)) {
2132                 if (ret != -EAGAIN)
2133                         vq_err(vq, "Translation failure %d in indirect.\n", ret);
2134                 return ret;
2135         }
2136         iov_iter_init(&from, READ, vq->indirect, ret, len);
2137
2138         /* We will use the result as an address to read from, so most
2139          * architectures only need a compiler barrier here. */
2140         read_barrier_depends();
2141
2142         count = len / sizeof desc;
2143         /* Buffers are chained via a 16 bit next field, so
2144          * we can have at most 2^16 of these. */
2145         if (unlikely(count > USHRT_MAX + 1)) {
2146                 vq_err(vq, "Indirect buffer length too big: %d\n",
2147                        indirect->len);
2148                 return -E2BIG;
2149         }
2150
2151         do {
2152                 unsigned iov_count = *in_num + *out_num;
2153                 if (unlikely(++found > count)) {
2154                         vq_err(vq, "Loop detected: last one at %u "
2155                                "indirect size %u\n",
2156                                i, count);
2157                         return -EINVAL;
2158                 }
2159                 if (unlikely(!copy_from_iter_full(&desc, sizeof(desc), &from))) {
2160                         vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n",
2161                                i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
2162                         return -EINVAL;
2163                 }
2164                 if (unlikely(desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT))) {
2165                         vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n",
2166                                i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
2167                         return -EINVAL;
2168                 }
2169
2170                 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
2171                         access = VHOST_ACCESS_WO;
2172                 else
2173                         access = VHOST_ACCESS_RO;
2174
2175                 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
2176                                      vhost32_to_cpu(vq, desc.len), iov + iov_count,
2177                                      iov_size - iov_count, access);
2178                 if (unlikely(ret < 0)) {
2179                         if (ret != -EAGAIN)
2180                                 vq_err(vq, "Translation failure %d indirect idx %d\n",
2181                                         ret, i);
2182                         return ret;
2183                 }
2184                 /* If this is an input descriptor, increment that count. */
2185                 if (access == VHOST_ACCESS_WO) {
2186                         *in_num += ret;
2187                         if (unlikely(log && ret)) {
2188                                 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
2189                                 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
2190                                 ++*log_num;
2191                         }
2192                 } else {
2193                         /* If it's an output descriptor, they're all supposed
2194                          * to come before any input descriptors. */
2195                         if (unlikely(*in_num)) {
2196                                 vq_err(vq, "Indirect descriptor "
2197                                        "has out after in: idx %d\n", i);
2198                                 return -EINVAL;
2199                         }
2200                         *out_num += ret;
2201                 }
2202         } while ((i = next_desc(vq, &desc)) != -1);
2203         return 0;
2204 }
2205
2206 /* This looks in the virtqueue and for the first available buffer, and converts
2207  * it to an iovec for convenient access.  Since descriptors consist of some
2208  * number of output then some number of input descriptors, it's actually two
2209  * iovecs, but we pack them into one and note how many of each there were.
2210  *
2211  * This function returns the descriptor number found, or vq->num (which is
2212  * never a valid descriptor number) if none was found.  A negative code is
2213  * returned on error. */
2214 int vhost_get_vq_desc(struct vhost_virtqueue *vq,
2215                       struct iovec iov[], unsigned int iov_size,
2216                       unsigned int *out_num, unsigned int *in_num,
2217                       struct vhost_log *log, unsigned int *log_num)
2218 {
2219         struct vring_desc desc;
2220         unsigned int i, head, found = 0;
2221         u16 last_avail_idx;
2222         __virtio16 avail_idx;
2223         __virtio16 ring_head;
2224         int ret, access;
2225
2226         /* Check it isn't doing very strange things with descriptor numbers. */
2227         last_avail_idx = vq->last_avail_idx;
2228
2229         if (vq->avail_idx == vq->last_avail_idx) {
2230                 if (unlikely(vhost_get_avail_idx(vq, &avail_idx))) {
2231                         vq_err(vq, "Failed to access avail idx at %p\n",
2232                                 &vq->avail->idx);
2233                         return -EFAULT;
2234                 }
2235                 vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
2236
2237                 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
2238                         vq_err(vq, "Guest moved used index from %u to %u",
2239                                 last_avail_idx, vq->avail_idx);
2240                         return -EFAULT;
2241                 }
2242
2243                 /* If there's nothing new since last we looked, return
2244                  * invalid.
2245                  */
2246                 if (vq->avail_idx == last_avail_idx)
2247                         return vq->num;
2248
2249                 /* Only get avail ring entries after they have been
2250                  * exposed by guest.
2251                  */
2252                 smp_rmb();
2253         }
2254
2255         /* Grab the next descriptor number they're advertising, and increment
2256          * the index we've seen. */
2257         if (unlikely(vhost_get_avail_head(vq, &ring_head, last_avail_idx))) {
2258                 vq_err(vq, "Failed to read head: idx %d address %p\n",
2259                        last_avail_idx,
2260                        &vq->avail->ring[last_avail_idx % vq->num]);
2261                 return -EFAULT;
2262         }
2263
2264         head = vhost16_to_cpu(vq, ring_head);
2265
2266         /* If their number is silly, that's an error. */
2267         if (unlikely(head >= vq->num)) {
2268                 vq_err(vq, "Guest says index %u > %u is available",
2269                        head, vq->num);
2270                 return -EINVAL;
2271         }
2272
2273         /* When we start there are none of either input nor output. */
2274         *out_num = *in_num = 0;
2275         if (unlikely(log))
2276                 *log_num = 0;
2277
2278         i = head;
2279         do {
2280                 unsigned iov_count = *in_num + *out_num;
2281                 if (unlikely(i >= vq->num)) {
2282                         vq_err(vq, "Desc index is %u > %u, head = %u",
2283                                i, vq->num, head);
2284                         return -EINVAL;
2285                 }
2286                 if (unlikely(++found > vq->num)) {
2287                         vq_err(vq, "Loop detected: last one at %u "
2288                                "vq size %u head %u\n",
2289                                i, vq->num, head);
2290                         return -EINVAL;
2291                 }
2292                 ret = vhost_get_desc(vq, &desc, i);
2293                 if (unlikely(ret)) {
2294                         vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
2295                                i, vq->desc + i);
2296                         return -EFAULT;
2297                 }
2298                 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT)) {
2299                         ret = get_indirect(vq, iov, iov_size,
2300                                            out_num, in_num,
2301                                            log, log_num, &desc);
2302                         if (unlikely(ret < 0)) {
2303                                 if (ret != -EAGAIN)
2304                                         vq_err(vq, "Failure detected "
2305                                                 "in indirect descriptor at idx %d\n", i);
2306                                 return ret;
2307                         }
2308                         continue;
2309                 }
2310
2311                 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
2312                         access = VHOST_ACCESS_WO;
2313                 else
2314                         access = VHOST_ACCESS_RO;
2315                 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
2316                                      vhost32_to_cpu(vq, desc.len), iov + iov_count,
2317                                      iov_size - iov_count, access);
2318                 if (unlikely(ret < 0)) {
2319                         if (ret != -EAGAIN)
2320                                 vq_err(vq, "Translation failure %d descriptor idx %d\n",
2321                                         ret, i);
2322                         return ret;
2323                 }
2324                 if (access == VHOST_ACCESS_WO) {
2325                         /* If this is an input descriptor,
2326                          * increment that count. */
2327                         *in_num += ret;
2328                         if (unlikely(log && ret)) {
2329                                 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
2330                                 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
2331                                 ++*log_num;
2332                         }
2333                 } else {
2334                         /* If it's an output descriptor, they're all supposed
2335                          * to come before any input descriptors. */
2336                         if (unlikely(*in_num)) {
2337                                 vq_err(vq, "Descriptor has out after in: "
2338                                        "idx %d\n", i);
2339                                 return -EINVAL;
2340                         }
2341                         *out_num += ret;
2342                 }
2343         } while ((i = next_desc(vq, &desc)) != -1);
2344
2345         /* On success, increment avail index. */
2346         vq->last_avail_idx++;
2347
2348         /* Assume notifications from guest are disabled at this point,
2349          * if they aren't we would need to update avail_event index. */
2350         BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
2351         return head;
2352 }
2353 EXPORT_SYMBOL_GPL(vhost_get_vq_desc);
2354
2355 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
2356 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
2357 {
2358         vq->last_avail_idx -= n;
2359 }
2360 EXPORT_SYMBOL_GPL(vhost_discard_vq_desc);
2361
2362 /* After we've used one of their buffers, we tell them about it.  We'll then
2363  * want to notify the guest, using eventfd. */
2364 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
2365 {
2366         struct vring_used_elem heads = {
2367                 cpu_to_vhost32(vq, head),
2368                 cpu_to_vhost32(vq, len)
2369         };
2370
2371         return vhost_add_used_n(vq, &heads, 1);
2372 }
2373 EXPORT_SYMBOL_GPL(vhost_add_used);
2374
2375 static int __vhost_add_used_n(struct vhost_virtqueue *vq,
2376                             struct vring_used_elem *heads,
2377                             unsigned count)
2378 {
2379         struct vring_used_elem __user *used;
2380         u16 old, new;
2381         int start;
2382
2383         start = vq->last_used_idx & (vq->num - 1);
2384         used = vq->used->ring + start;
2385         if (vhost_put_used(vq, heads, start, count)) {
2386                 vq_err(vq, "Failed to write used");
2387                 return -EFAULT;
2388         }
2389         if (unlikely(vq->log_used)) {
2390                 /* Make sure data is seen before log. */
2391                 smp_wmb();
2392                 /* Log used ring entry write. */
2393                 log_used(vq, ((void __user *)used - (void __user *)vq->used),
2394                          count * sizeof *used);
2395         }
2396         old = vq->last_used_idx;
2397         new = (vq->last_used_idx += count);
2398         /* If the driver never bothers to signal in a very long while,
2399          * used index might wrap around. If that happens, invalidate
2400          * signalled_used index we stored. TODO: make sure driver
2401          * signals at least once in 2^16 and remove this. */
2402         if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old)))
2403                 vq->signalled_used_valid = false;
2404         return 0;
2405 }
2406
2407 /* After we've used one of their buffers, we tell them about it.  We'll then
2408  * want to notify the guest, using eventfd. */
2409 int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
2410                      unsigned count)
2411 {
2412         int start, n, r;
2413
2414         start = vq->last_used_idx & (vq->num - 1);
2415         n = vq->num - start;
2416         if (n < count) {
2417                 r = __vhost_add_used_n(vq, heads, n);
2418                 if (r < 0)
2419                         return r;
2420                 heads += n;
2421                 count -= n;
2422         }
2423         r = __vhost_add_used_n(vq, heads, count);
2424
2425         /* Make sure buffer is written before we update index. */
2426         smp_wmb();
2427         if (vhost_put_used_idx(vq)) {
2428                 vq_err(vq, "Failed to increment used idx");
2429                 return -EFAULT;
2430         }
2431         if (unlikely(vq->log_used)) {
2432                 /* Make sure used idx is seen before log. */
2433                 smp_wmb();
2434                 /* Log used index update. */
2435                 log_used(vq, offsetof(struct vring_used, idx),
2436                          sizeof vq->used->idx);
2437                 if (vq->log_ctx)
2438                         eventfd_signal(vq->log_ctx, 1);
2439         }
2440         return r;
2441 }
2442 EXPORT_SYMBOL_GPL(vhost_add_used_n);
2443
2444 static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2445 {
2446         __u16 old, new;
2447         __virtio16 event;
2448         bool v;
2449         /* Flush out used index updates. This is paired
2450          * with the barrier that the Guest executes when enabling
2451          * interrupts. */
2452         smp_mb();
2453
2454         if (vhost_has_feature(vq, VIRTIO_F_NOTIFY_ON_EMPTY) &&
2455             unlikely(vq->avail_idx == vq->last_avail_idx))
2456                 return true;
2457
2458         if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2459                 __virtio16 flags;
2460                 if (vhost_get_avail_flags(vq, &flags)) {
2461                         vq_err(vq, "Failed to get flags");
2462                         return true;
2463                 }
2464                 return !(flags & cpu_to_vhost16(vq, VRING_AVAIL_F_NO_INTERRUPT));
2465         }
2466         old = vq->signalled_used;
2467         v = vq->signalled_used_valid;
2468         new = vq->signalled_used = vq->last_used_idx;
2469         vq->signalled_used_valid = true;
2470
2471         if (unlikely(!v))
2472                 return true;
2473
2474         if (vhost_get_used_event(vq, &event)) {
2475                 vq_err(vq, "Failed to get used event idx");
2476                 return true;
2477         }
2478         return vring_need_event(vhost16_to_cpu(vq, event), new, old);
2479 }
2480
2481 /* This actually signals the guest, using eventfd. */
2482 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2483 {
2484         /* Signal the Guest tell them we used something up. */
2485         if (vq->call_ctx && vhost_notify(dev, vq))
2486                 eventfd_signal(vq->call_ctx, 1);
2487 }
2488 EXPORT_SYMBOL_GPL(vhost_signal);
2489
2490 /* And here's the combo meal deal.  Supersize me! */
2491 void vhost_add_used_and_signal(struct vhost_dev *dev,
2492                                struct vhost_virtqueue *vq,
2493                                unsigned int head, int len)
2494 {
2495         vhost_add_used(vq, head, len);
2496         vhost_signal(dev, vq);
2497 }
2498 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal);
2499
2500 /* multi-buffer version of vhost_add_used_and_signal */
2501 void vhost_add_used_and_signal_n(struct vhost_dev *dev,
2502                                  struct vhost_virtqueue *vq,
2503                                  struct vring_used_elem *heads, unsigned count)
2504 {
2505         vhost_add_used_n(vq, heads, count);
2506         vhost_signal(dev, vq);
2507 }
2508 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n);
2509
2510 /* return true if we're sure that avaiable ring is empty */
2511 bool vhost_vq_avail_empty(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2512 {
2513         __virtio16 avail_idx;
2514         int r;
2515
2516         if (vq->avail_idx != vq->last_avail_idx)
2517                 return false;
2518
2519         r = vhost_get_avail_idx(vq, &avail_idx);
2520         if (unlikely(r))
2521                 return false;
2522         vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
2523
2524         return vq->avail_idx == vq->last_avail_idx;
2525 }
2526 EXPORT_SYMBOL_GPL(vhost_vq_avail_empty);
2527
2528 /* OK, now we need to know about added descriptors. */
2529 bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2530 {
2531         __virtio16 avail_idx;
2532         int r;
2533
2534         if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
2535                 return false;
2536         vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
2537         if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2538                 r = vhost_update_used_flags(vq);
2539                 if (r) {
2540                         vq_err(vq, "Failed to enable notification at %p: %d\n",
2541                                &vq->used->flags, r);
2542                         return false;
2543                 }
2544         } else {
2545                 r = vhost_update_avail_event(vq, vq->avail_idx);
2546                 if (r) {
2547                         vq_err(vq, "Failed to update avail event index at %p: %d\n",
2548                                vhost_avail_event(vq), r);
2549                         return false;
2550                 }
2551         }
2552         /* They could have slipped one in as we were doing that: make
2553          * sure it's written, then check again. */
2554         smp_mb();
2555         r = vhost_get_avail_idx(vq, &avail_idx);
2556         if (r) {
2557                 vq_err(vq, "Failed to check avail idx at %p: %d\n",
2558                        &vq->avail->idx, r);
2559                 return false;
2560         }
2561
2562         return vhost16_to_cpu(vq, avail_idx) != vq->avail_idx;
2563 }
2564 EXPORT_SYMBOL_GPL(vhost_enable_notify);
2565
2566 /* We don't need to be notified again. */
2567 void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2568 {
2569         int r;
2570
2571         if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
2572                 return;
2573         vq->used_flags |= VRING_USED_F_NO_NOTIFY;
2574         if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2575                 r = vhost_update_used_flags(vq);
2576                 if (r)
2577                         vq_err(vq, "Failed to enable notification at %p: %d\n",
2578                                &vq->used->flags, r);
2579         }
2580 }
2581 EXPORT_SYMBOL_GPL(vhost_disable_notify);
2582
2583 /* Create a new message. */
2584 struct vhost_msg_node *vhost_new_msg(struct vhost_virtqueue *vq, int type)
2585 {
2586         struct vhost_msg_node *node = kmalloc(sizeof *node, GFP_KERNEL);
2587         if (!node)
2588                 return NULL;
2589
2590         /* Make sure all padding within the structure is initialized. */
2591         memset(&node->msg, 0, sizeof node->msg);
2592         node->vq = vq;
2593         node->msg.type = type;
2594         return node;
2595 }
2596 EXPORT_SYMBOL_GPL(vhost_new_msg);
2597
2598 void vhost_enqueue_msg(struct vhost_dev *dev, struct list_head *head,
2599                        struct vhost_msg_node *node)
2600 {
2601         spin_lock(&dev->iotlb_lock);
2602         list_add_tail(&node->node, head);
2603         spin_unlock(&dev->iotlb_lock);
2604
2605         wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
2606 }
2607 EXPORT_SYMBOL_GPL(vhost_enqueue_msg);
2608
2609 struct vhost_msg_node *vhost_dequeue_msg(struct vhost_dev *dev,
2610                                          struct list_head *head)
2611 {
2612         struct vhost_msg_node *node = NULL;
2613
2614         spin_lock(&dev->iotlb_lock);
2615         if (!list_empty(head)) {
2616                 node = list_first_entry(head, struct vhost_msg_node,
2617                                         node);
2618                 list_del(&node->node);
2619         }
2620         spin_unlock(&dev->iotlb_lock);
2621
2622         return node;
2623 }
2624 EXPORT_SYMBOL_GPL(vhost_dequeue_msg);
2625
2626
2627 static int __init vhost_init(void)
2628 {
2629         return 0;
2630 }
2631
2632 static void __exit vhost_exit(void)
2633 {
2634 }
2635
2636 module_init(vhost_init);
2637 module_exit(vhost_exit);
2638
2639 MODULE_VERSION("0.0.1");
2640 MODULE_LICENSE("GPL v2");
2641 MODULE_AUTHOR("Michael S. Tsirkin");
2642 MODULE_DESCRIPTION("Host kernel accelerator for virtio");