drivers/vhost/vhost.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* Copyright (C) 2009 Red Hat, Inc.
   3  * Copyright (C) 2006 Rusty Russell IBM Corporation
   4  *
   5  * Author: Michael S. Tsirkin <mst@redhat.com>
   6  *
   7  * Inspiration, some code, and most witty comments come from
   8  * Documentation/virtual/lguest/lguest.c, by Rusty Russell
   9  *
  10  * Generic code for virtio server in host kernel.
  11  */
  12
  13 #include <linux/eventfd.h>
  14 #include <linux/vhost.h>
  15 #include <linux/uio.h>
  16 #include <linux/mm.h>
  17 #include <linux/miscdevice.h>
  18 #include <linux/mutex.h>
  19 #include <linux/poll.h>
  20 #include <linux/file.h>
  21 #include <linux/highmem.h>
  22 #include <linux/slab.h>
  23 #include <linux/vmalloc.h>
  24 #include <linux/kthread.h>
  25 #include <linux/module.h>
  26 #include <linux/sort.h>
  27 #include <linux/sched/mm.h>
  28 #include <linux/sched/signal.h>
  29 #include <linux/sched/vhost_task.h>
  30 #include <linux/interval_tree_generic.h>
  31 #include <linux/nospec.h>
  32 #include <linux/kcov.h>
  33
  34 #include "vhost.h"
  35
  36 static ushort max_mem_regions = 64;
  37 module_param(max_mem_regions, ushort, 0444);
  38 MODULE_PARM_DESC(max_mem_regions,
  39         "Maximum number of memory regions in memory map. (default: 64)");
  40 static int max_iotlb_entries = 2048;
  41 module_param(max_iotlb_entries, int, 0444);
  42 MODULE_PARM_DESC(max_iotlb_entries,
  43         "Maximum number of iotlb entries. (default: 2048)");
  44
  45 enum {
  46         VHOST_MEMORY_F_LOG = 0x1,
  47 };
  48
  49 #define vhost_used_event(vq) ((__virtio16 __user *)&vq->avail->ring[vq->num])
  50 #define vhost_avail_event(vq) ((__virtio16 __user *)&vq->used->ring[vq->num])
  51
  52 #ifdef CONFIG_VHOST_CROSS_ENDIAN_LEGACY
  53 static void vhost_disable_cross_endian(struct vhost_virtqueue *vq)
  54 {
  55         vq->user_be = !virtio_legacy_is_little_endian();
  56 }
  57
  58 static void vhost_enable_cross_endian_big(struct vhost_virtqueue *vq)
  59 {
  60         vq->user_be = true;
  61 }
  62
  63 static void vhost_enable_cross_endian_little(struct vhost_virtqueue *vq)
  64 {
  65         vq->user_be = false;
  66 }
  67
  68 static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp)
  69 {
  70         struct vhost_vring_state s;
  71
  72         if (vq->private_data)
  73                 return -EBUSY;
  74
  75         if (copy_from_user(&s, argp, sizeof(s)))
  76                 return -EFAULT;
  77
  78         if (s.num != VHOST_VRING_LITTLE_ENDIAN &&
  79             s.num != VHOST_VRING_BIG_ENDIAN)
  80                 return -EINVAL;
  81
  82         if (s.num == VHOST_VRING_BIG_ENDIAN)
  83                 vhost_enable_cross_endian_big(vq);
  84         else
  85                 vhost_enable_cross_endian_little(vq);
  86
  87         return 0;
  88 }
  89
  90 static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx,
  91                                    int __user *argp)
  92 {
  93         struct vhost_vring_state s = {
  94                 .index = idx,
  95                 .num = vq->user_be
  96         };
  97
  98         if (copy_to_user(argp, &s, sizeof(s)))
  99                 return -EFAULT;
 100
 101         return 0;
 102 }
 103
 104 static void vhost_init_is_le(struct vhost_virtqueue *vq)
 105 {
 106         /* Note for legacy virtio: user_be is initialized at reset time
 107          * according to the host endianness. If userspace does not set an
 108          * explicit endianness, the default behavior is native endian, as
 109          * expected by legacy virtio.
 110          */
 111         vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1) || !vq->user_be;
 112 }
 113 #else
 114 static void vhost_disable_cross_endian(struct vhost_virtqueue *vq)
 115 {
 116 }
 117
 118 static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp)
 119 {
 120         return -ENOIOCTLCMD;
 121 }
 122
 123 static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx,
 124                                    int __user *argp)
 125 {
 126         return -ENOIOCTLCMD;
 127 }
 128
 129 static void vhost_init_is_le(struct vhost_virtqueue *vq)
 130 {
 131         vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1)
 132                 || virtio_legacy_is_little_endian();
 133 }
 134 #endif /* CONFIG_VHOST_CROSS_ENDIAN_LEGACY */
 135
 136 static void vhost_reset_is_le(struct vhost_virtqueue *vq)
 137 {
 138         vhost_init_is_le(vq);
 139 }
 140
 141 struct vhost_flush_struct {
 142         struct vhost_work work;
 143         struct completion wait_event;
 144 };
 145
 146 static void vhost_flush_work(struct vhost_work *work)
 147 {
 148         struct vhost_flush_struct *s;
 149
 150         s = container_of(work, struct vhost_flush_struct, work);
 151         complete(&s->wait_event);
 152 }
 153
 154 static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh,
 155                             poll_table *pt)
 156 {
 157         struct vhost_poll *poll;
 158
 159         poll = container_of(pt, struct vhost_poll, table);
 160         poll->wqh = wqh;
 161         add_wait_queue(wqh, &poll->wait);
 162 }
 163
 164 static int vhost_poll_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync,
 165                              void *key)
 166 {
 167         struct vhost_poll *poll = container_of(wait, struct vhost_poll, wait);
 168         struct vhost_work *work = &poll->work;
 169
 170         if (!(key_to_poll(key) & poll->mask))
 171                 return 0;
 172
 173         if (!poll->dev->use_worker)
 174                 work->fn(work);
 175         else
 176                 vhost_poll_queue(poll);
 177
 178         return 0;
 179 }
 180
 181 void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn)
 182 {
 183         clear_bit(VHOST_WORK_QUEUED, &work->flags);
 184         work->fn = fn;
 185 }
 186 EXPORT_SYMBOL_GPL(vhost_work_init);
 187
 188 /* Init poll structure */
 189 void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
 190                      __poll_t mask, struct vhost_dev *dev,
 191                      struct vhost_virtqueue *vq)
 192 {
 193         init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup);
 194         init_poll_funcptr(&poll->table, vhost_poll_func);
 195         poll->mask = mask;
 196         poll->dev = dev;
 197         poll->wqh = NULL;
 198         poll->vq = vq;
 199
 200         vhost_work_init(&poll->work, fn);
 201 }
 202 EXPORT_SYMBOL_GPL(vhost_poll_init);
 203
 204 /* Start polling a file. We add ourselves to file's wait queue. The caller must
 205  * keep a reference to a file until after vhost_poll_stop is called. */
 206 int vhost_poll_start(struct vhost_poll *poll, struct file *file)
 207 {
 208         __poll_t mask;
 209
 210         if (poll->wqh)
 211                 return 0;
 212
 213         mask = vfs_poll(file, &poll->table);
 214         if (mask)
 215                 vhost_poll_wakeup(&poll->wait, 0, 0, poll_to_key(mask));
 216         if (mask & EPOLLERR) {
 217                 vhost_poll_stop(poll);
 218                 return -EINVAL;
 219         }
 220
 221         return 0;
 222 }
 223 EXPORT_SYMBOL_GPL(vhost_poll_start);
 224
 225 /* Stop polling a file. After this function returns, it becomes safe to drop the
 226  * file reference. You must also flush afterwards. */
 227 void vhost_poll_stop(struct vhost_poll *poll)
 228 {
 229         if (poll->wqh) {
 230                 remove_wait_queue(poll->wqh, &poll->wait);
 231                 poll->wqh = NULL;
 232         }
 233 }
 234 EXPORT_SYMBOL_GPL(vhost_poll_stop);
 235
 236 static bool vhost_worker_queue(struct vhost_worker *worker,
 237                                struct vhost_work *work)
 238 {
 239         if (!worker)
 240                 return false;
 241         /*
 242          * vsock can queue while we do a VHOST_SET_OWNER, so we have a smp_wmb
 243          * when setting up the worker. We don't have a smp_rmb here because
 244          * test_and_set_bit gives us a mb already.
 245          */
 246         if (!test_and_set_bit(VHOST_WORK_QUEUED, &work->flags)) {
 247                 /* We can only add the work to the list after we're
 248                  * sure it was not in the list.
 249                  * test_and_set_bit() implies a memory barrier.
 250                  */
 251                 llist_add(&work->node, &worker->work_list);
 252                 vhost_task_wake(worker->vtsk);
 253         }
 254
 255         return true;
 256 }
 257
 258 bool vhost_vq_work_queue(struct vhost_virtqueue *vq, struct vhost_work *work)
 259 {
 260         return vhost_worker_queue(vq->worker, work);
 261 }
 262 EXPORT_SYMBOL_GPL(vhost_vq_work_queue);
 263
 264 static void vhost_worker_flush(struct vhost_worker *worker)
 265 {
 266         struct vhost_flush_struct flush;
 267
 268         init_completion(&flush.wait_event);
 269         vhost_work_init(&flush.work, vhost_flush_work);
 270
 271         if (vhost_worker_queue(worker, &flush.work))
 272                 wait_for_completion(&flush.wait_event);
 273 }
 274
 275 void vhost_vq_flush(struct vhost_virtqueue *vq)
 276 {
 277         vhost_worker_flush(vq->worker);
 278 }
 279 EXPORT_SYMBOL_GPL(vhost_vq_flush);
 280
 281 void vhost_dev_flush(struct vhost_dev *dev)
 282 {
 283         vhost_worker_flush(dev->worker);
 284 }
 285 EXPORT_SYMBOL_GPL(vhost_dev_flush);
 286
 287 /* A lockless hint for busy polling code to exit the loop */
 288 bool vhost_vq_has_work(struct vhost_virtqueue *vq)
 289 {
 290         return !llist_empty(&vq->worker->work_list);
 291 }
 292 EXPORT_SYMBOL_GPL(vhost_vq_has_work);
 293
 294 void vhost_poll_queue(struct vhost_poll *poll)
 295 {
 296         vhost_vq_work_queue(poll->vq, &poll->work);
 297 }
 298 EXPORT_SYMBOL_GPL(vhost_poll_queue);
 299
 300 static void __vhost_vq_meta_reset(struct vhost_virtqueue *vq)
 301 {
 302         int j;
 303
 304         for (j = 0; j < VHOST_NUM_ADDRS; j++)
 305                 vq->meta_iotlb[j] = NULL;
 306 }
 307
 308 static void vhost_vq_meta_reset(struct vhost_dev *d)
 309 {
 310         int i;
 311
 312         for (i = 0; i < d->nvqs; ++i)
 313                 __vhost_vq_meta_reset(d->vqs[i]);
 314 }
 315
 316 static void vhost_vring_call_reset(struct vhost_vring_call *call_ctx)
 317 {
 318         call_ctx->ctx = NULL;
 319         memset(&call_ctx->producer, 0x0, sizeof(struct irq_bypass_producer));
 320 }
 321
 322 bool vhost_vq_is_setup(struct vhost_virtqueue *vq)
 323 {
 324         return vq->avail && vq->desc && vq->used && vhost_vq_access_ok(vq);
 325 }
 326 EXPORT_SYMBOL_GPL(vhost_vq_is_setup);
 327
 328 static void vhost_vq_reset(struct vhost_dev *dev,
 329                            struct vhost_virtqueue *vq)
 330 {
 331         vq->num = 1;
 332         vq->desc = NULL;
 333         vq->avail = NULL;
 334         vq->used = NULL;
 335         vq->last_avail_idx = 0;
 336         vq->avail_idx = 0;
 337         vq->last_used_idx = 0;
 338         vq->signalled_used = 0;
 339         vq->signalled_used_valid = false;
 340         vq->used_flags = 0;
 341         vq->log_used = false;
 342         vq->log_addr = -1ull;
 343         vq->private_data = NULL;
 344         vq->acked_features = 0;
 345         vq->acked_backend_features = 0;
 346         vq->log_base = NULL;
 347         vq->error_ctx = NULL;
 348         vq->kick = NULL;
 349         vq->log_ctx = NULL;
 350         vhost_disable_cross_endian(vq);
 351         vhost_reset_is_le(vq);
 352         vq->busyloop_timeout = 0;
 353         vq->umem = NULL;
 354         vq->iotlb = NULL;
 355         vq->worker = NULL;
 356         vhost_vring_call_reset(&vq->call_ctx);
 357         __vhost_vq_meta_reset(vq);
 358 }
 359
 360 static bool vhost_worker(void *data)
 361 {
 362         struct vhost_worker *worker = data;
 363         struct vhost_work *work, *work_next;
 364         struct llist_node *node;
 365
 366         node = llist_del_all(&worker->work_list);
 367         if (node) {
 368                 __set_current_state(TASK_RUNNING);
 369
 370                 node = llist_reverse_order(node);
 371                 /* make sure flag is seen after deletion */
 372                 smp_wmb();
 373                 llist_for_each_entry_safe(work, work_next, node, node) {
 374                         clear_bit(VHOST_WORK_QUEUED, &work->flags);
 375                         kcov_remote_start_common(worker->kcov_handle);
 376                         work->fn(work);
 377                         kcov_remote_stop();
 378                         cond_resched();
 379                 }
 380         }
 381
 382         return !!node;
 383 }
 384
 385 static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq)
 386 {
 387         kfree(vq->indirect);
 388         vq->indirect = NULL;
 389         kfree(vq->log);
 390         vq->log = NULL;
 391         kfree(vq->heads);
 392         vq->heads = NULL;
 393 }
 394
 395 /* Helper to allocate iovec buffers for all vqs. */
 396 static long vhost_dev_alloc_iovecs(struct vhost_dev *dev)
 397 {
 398         struct vhost_virtqueue *vq;
 399         int i;
 400
 401         for (i = 0; i < dev->nvqs; ++i) {
 402                 vq = dev->vqs[i];
 403                 vq->indirect = kmalloc_array(UIO_MAXIOV,
 404                                              sizeof(*vq->indirect),
 405                                              GFP_KERNEL);
 406                 vq->log = kmalloc_array(dev->iov_limit, sizeof(*vq->log),
 407                                         GFP_KERNEL);
 408                 vq->heads = kmalloc_array(dev->iov_limit, sizeof(*vq->heads),
 409                                           GFP_KERNEL);
 410                 if (!vq->indirect || !vq->log || !vq->heads)
 411                         goto err_nomem;
 412         }
 413         return 0;
 414
 415 err_nomem:
 416         for (; i >= 0; --i)
 417                 vhost_vq_free_iovecs(dev->vqs[i]);
 418         return -ENOMEM;
 419 }
 420
 421 static void vhost_dev_free_iovecs(struct vhost_dev *dev)
 422 {
 423         int i;
 424
 425         for (i = 0; i < dev->nvqs; ++i)
 426                 vhost_vq_free_iovecs(dev->vqs[i]);
 427 }
 428
 429 bool vhost_exceeds_weight(struct vhost_virtqueue *vq,
 430                           int pkts, int total_len)
 431 {
 432         struct vhost_dev *dev = vq->dev;
 433
 434         if ((dev->byte_weight && total_len >= dev->byte_weight) ||
 435             pkts >= dev->weight) {
 436                 vhost_poll_queue(&vq->poll);
 437                 return true;
 438         }
 439
 440         return false;
 441 }
 442 EXPORT_SYMBOL_GPL(vhost_exceeds_weight);
 443
 444 static size_t vhost_get_avail_size(struct vhost_virtqueue *vq,
 445                                    unsigned int num)
 446 {
 447         size_t event __maybe_unused =
 448                vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
 449
 450         return size_add(struct_size(vq->avail, ring, num), event);
 451 }
 452
 453 static size_t vhost_get_used_size(struct vhost_virtqueue *vq,
 454                                   unsigned int num)
 455 {
 456         size_t event __maybe_unused =
 457                vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
 458
 459         return size_add(struct_size(vq->used, ring, num), event);
 460 }
 461
 462 static size_t vhost_get_desc_size(struct vhost_virtqueue *vq,
 463                                   unsigned int num)
 464 {
 465         return sizeof(*vq->desc) * num;
 466 }
 467
 468 void vhost_dev_init(struct vhost_dev *dev,
 469                     struct vhost_virtqueue **vqs, int nvqs,
 470                     int iov_limit, int weight, int byte_weight,
 471                     bool use_worker,
 472                     int (*msg_handler)(struct vhost_dev *dev, u32 asid,
 473                                        struct vhost_iotlb_msg *msg))
 474 {
 475         struct vhost_virtqueue *vq;
 476         int i;
 477
 478         dev->vqs = vqs;
 479         dev->nvqs = nvqs;
 480         mutex_init(&dev->mutex);
 481         dev->log_ctx = NULL;
 482         dev->umem = NULL;
 483         dev->iotlb = NULL;
 484         dev->mm = NULL;
 485         dev->worker = NULL;
 486         dev->iov_limit = iov_limit;
 487         dev->weight = weight;
 488         dev->byte_weight = byte_weight;
 489         dev->use_worker = use_worker;
 490         dev->msg_handler = msg_handler;
 491         init_waitqueue_head(&dev->wait);
 492         INIT_LIST_HEAD(&dev->read_list);
 493         INIT_LIST_HEAD(&dev->pending_list);
 494         spin_lock_init(&dev->iotlb_lock);
 495
 496
 497         for (i = 0; i < dev->nvqs; ++i) {
 498                 vq = dev->vqs[i];
 499                 vq->log = NULL;
 500                 vq->indirect = NULL;
 501                 vq->heads = NULL;
 502                 vq->dev = dev;
 503                 mutex_init(&vq->mutex);
 504                 vhost_vq_reset(dev, vq);
 505                 if (vq->handle_kick)
 506                         vhost_poll_init(&vq->poll, vq->handle_kick,
 507                                         EPOLLIN, dev, vq);
 508         }
 509 }
 510 EXPORT_SYMBOL_GPL(vhost_dev_init);
 511
 512 /* Caller should have device mutex */
 513 long vhost_dev_check_owner(struct vhost_dev *dev)
 514 {
 515         /* Are you the owner? If not, I don't think you mean to do that */
 516         return dev->mm == current->mm ? 0 : -EPERM;
 517 }
 518 EXPORT_SYMBOL_GPL(vhost_dev_check_owner);
 519
 520 /* Caller should have device mutex */
 521 bool vhost_dev_has_owner(struct vhost_dev *dev)
 522 {
 523         return dev->mm;
 524 }
 525 EXPORT_SYMBOL_GPL(vhost_dev_has_owner);
 526
 527 static void vhost_attach_mm(struct vhost_dev *dev)
 528 {
 529         /* No owner, become one */
 530         if (dev->use_worker) {
 531                 dev->mm = get_task_mm(current);
 532         } else {
 533                 /* vDPA device does not use worker thead, so there's
 534                  * no need to hold the address space for mm. This help
 535                  * to avoid deadlock in the case of mmap() which may
 536                  * held the refcnt of the file and depends on release
 537                  * method to remove vma.
 538                  */
 539                 dev->mm = current->mm;
 540                 mmgrab(dev->mm);
 541         }
 542 }
 543
 544 static void vhost_detach_mm(struct vhost_dev *dev)
 545 {
 546         if (!dev->mm)
 547                 return;
 548
 549         if (dev->use_worker)
 550                 mmput(dev->mm);
 551         else
 552                 mmdrop(dev->mm);
 553
 554         dev->mm = NULL;
 555 }
 556
 557 static void vhost_worker_free(struct vhost_dev *dev)
 558 {
 559         if (!dev->worker)
 560                 return;
 561
 562         WARN_ON(!llist_empty(&dev->worker->work_list));
 563         vhost_task_stop(dev->worker->vtsk);
 564         kfree(dev->worker);
 565         dev->worker = NULL;
 566 }
 567
 568 static struct vhost_worker *vhost_worker_create(struct vhost_dev *dev)
 569 {
 570         struct vhost_worker *worker;
 571         struct vhost_task *vtsk;
 572         char name[TASK_COMM_LEN];
 573
 574         worker = kzalloc(sizeof(*worker), GFP_KERNEL_ACCOUNT);
 575         if (!worker)
 576                 return NULL;
 577
 578         snprintf(name, sizeof(name), "vhost-%d", current->pid);
 579
 580         vtsk = vhost_task_create(vhost_worker, worker, name);
 581         if (!vtsk)
 582                 goto free_worker;
 583
 584         init_llist_head(&worker->work_list);
 585         worker->kcov_handle = kcov_common_handle();
 586         worker->vtsk = vtsk;
 587         /*
 588          * vsock can already try to queue so make sure llist and vtsk are both
 589          * set before vhost_work_queue sees dev->worker is set.
 590          */
 591         smp_wmb();
 592         dev->worker = worker;
 593
 594         vhost_task_start(vtsk);
 595         return worker;
 596
 597 free_worker:
 598         kfree(worker);
 599         return NULL;
 600 }
 601
 602 static int vhost_get_vq_from_user(struct vhost_dev *dev, void __user *argp,
 603                                   struct vhost_virtqueue **vq, u32 *id)
 604 {
 605         u32 __user *idxp = argp;
 606         u32 idx;
 607         long r;
 608
 609         r = get_user(idx, idxp);
 610         if (r < 0)
 611                 return r;
 612
 613         if (idx >= dev->nvqs)
 614                 return -ENOBUFS;
 615
 616         idx = array_index_nospec(idx, dev->nvqs);
 617
 618         *vq = dev->vqs[idx];
 619         *id = idx;
 620         return 0;
 621 }
 622
 623 /* Caller should have device mutex */
 624 long vhost_dev_set_owner(struct vhost_dev *dev)
 625 {
 626         struct vhost_worker *worker;
 627         int err, i;
 628
 629         /* Is there an owner already? */
 630         if (vhost_dev_has_owner(dev)) {
 631                 err = -EBUSY;
 632                 goto err_mm;
 633         }
 634
 635         vhost_attach_mm(dev);
 636
 637         err = vhost_dev_alloc_iovecs(dev);
 638         if (err)
 639                 goto err_iovecs;
 640
 641         if (dev->use_worker) {
 642                 /*
 643                  * This should be done last, because vsock can queue work
 644                  * before VHOST_SET_OWNER so it simplifies the failure path
 645                  * below since we don't have to worry about vsock queueing
 646                  * while we free the worker.
 647                  */
 648                 worker = vhost_worker_create(dev);
 649                 if (!worker) {
 650                         err = -ENOMEM;
 651                         goto err_worker;
 652                 }
 653
 654                 for (i = 0; i < dev->nvqs; i++)
 655                         dev->vqs[i]->worker = worker;
 656         }
 657
 658         return 0;
 659
 660 err_worker:
 661         vhost_dev_free_iovecs(dev);
 662 err_iovecs:
 663         vhost_detach_mm(dev);
 664 err_mm:
 665         return err;
 666 }
 667 EXPORT_SYMBOL_GPL(vhost_dev_set_owner);
 668
 669 static struct vhost_iotlb *iotlb_alloc(void)
 670 {
 671         return vhost_iotlb_alloc(max_iotlb_entries,
 672                                  VHOST_IOTLB_FLAG_RETIRE);
 673 }
 674
 675 struct vhost_iotlb *vhost_dev_reset_owner_prepare(void)
 676 {
 677         return iotlb_alloc();
 678 }
 679 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner_prepare);
 680
 681 /* Caller should have device mutex */
 682 void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_iotlb *umem)
 683 {
 684         int i;
 685
 686         vhost_dev_cleanup(dev);
 687
 688         dev->umem = umem;
 689         /* We don't need VQ locks below since vhost_dev_cleanup makes sure
 690          * VQs aren't running.
 691          */
 692         for (i = 0; i < dev->nvqs; ++i)
 693                 dev->vqs[i]->umem = umem;
 694 }
 695 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner);
 696
 697 void vhost_dev_stop(struct vhost_dev *dev)
 698 {
 699         int i;
 700
 701         for (i = 0; i < dev->nvqs; ++i) {
 702                 if (dev->vqs[i]->kick && dev->vqs[i]->handle_kick)
 703                         vhost_poll_stop(&dev->vqs[i]->poll);
 704         }
 705
 706         vhost_dev_flush(dev);
 707 }
 708 EXPORT_SYMBOL_GPL(vhost_dev_stop);
 709
 710 void vhost_clear_msg(struct vhost_dev *dev)
 711 {
 712         struct vhost_msg_node *node, *n;
 713
 714         spin_lock(&dev->iotlb_lock);
 715
 716         list_for_each_entry_safe(node, n, &dev->read_list, node) {
 717                 list_del(&node->node);
 718                 kfree(node);
 719         }
 720
 721         list_for_each_entry_safe(node, n, &dev->pending_list, node) {
 722                 list_del(&node->node);
 723                 kfree(node);
 724         }
 725
 726         spin_unlock(&dev->iotlb_lock);
 727 }
 728 EXPORT_SYMBOL_GPL(vhost_clear_msg);
 729
 730 void vhost_dev_cleanup(struct vhost_dev *dev)
 731 {
 732         int i;
 733
 734         for (i = 0; i < dev->nvqs; ++i) {
 735                 if (dev->vqs[i]->error_ctx)
 736                         eventfd_ctx_put(dev->vqs[i]->error_ctx);
 737                 if (dev->vqs[i]->kick)
 738                         fput(dev->vqs[i]->kick);
 739                 if (dev->vqs[i]->call_ctx.ctx)
 740                         eventfd_ctx_put(dev->vqs[i]->call_ctx.ctx);
 741                 vhost_vq_reset(dev, dev->vqs[i]);
 742         }
 743         vhost_dev_free_iovecs(dev);
 744         if (dev->log_ctx)
 745                 eventfd_ctx_put(dev->log_ctx);
 746         dev->log_ctx = NULL;
 747         /* No one will access memory at this point */
 748         vhost_iotlb_free(dev->umem);
 749         dev->umem = NULL;
 750         vhost_iotlb_free(dev->iotlb);
 751         dev->iotlb = NULL;
 752         vhost_clear_msg(dev);
 753         wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
 754         vhost_worker_free(dev);
 755         vhost_detach_mm(dev);
 756 }
 757 EXPORT_SYMBOL_GPL(vhost_dev_cleanup);
 758
 759 static bool log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
 760 {
 761         u64 a = addr / VHOST_PAGE_SIZE / 8;
 762
 763         /* Make sure 64 bit math will not overflow. */
 764         if (a > ULONG_MAX - (unsigned long)log_base ||
 765             a + (unsigned long)log_base > ULONG_MAX)
 766                 return false;
 767
 768         return access_ok(log_base + a,
 769                          (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8);
 770 }
 771
 772 /* Make sure 64 bit math will not overflow. */
 773 static bool vhost_overflow(u64 uaddr, u64 size)
 774 {
 775         if (uaddr > ULONG_MAX || size > ULONG_MAX)
 776                 return true;
 777
 778         if (!size)
 779                 return false;
 780
 781         return uaddr > ULONG_MAX - size + 1;
 782 }
 783
 784 /* Caller should have vq mutex and device mutex. */
 785 static bool vq_memory_access_ok(void __user *log_base, struct vhost_iotlb *umem,
 786                                 int log_all)
 787 {
 788         struct vhost_iotlb_map *map;
 789
 790         if (!umem)
 791                 return false;
 792
 793         list_for_each_entry(map, &umem->list, link) {
 794                 unsigned long a = map->addr;
 795
 796                 if (vhost_overflow(map->addr, map->size))
 797                         return false;
 798
 799
 800                 if (!access_ok((void __user *)a, map->size))
 801                         return false;
 802                 else if (log_all && !log_access_ok(log_base,
 803                                                    map->start,
 804                                                    map->size))
 805                         return false;
 806         }
 807         return true;
 808 }
 809
 810 static inline void __user *vhost_vq_meta_fetch(struct vhost_virtqueue *vq,
 811                                                u64 addr, unsigned int size,
 812                                                int type)
 813 {
 814         const struct vhost_iotlb_map *map = vq->meta_iotlb[type];
 815
 816         if (!map)
 817                 return NULL;
 818
 819         return (void __user *)(uintptr_t)(map->addr + addr - map->start);
 820 }
 821
 822 /* Can we switch to this memory table? */
 823 /* Caller should have device mutex but not vq mutex */
 824 static bool memory_access_ok(struct vhost_dev *d, struct vhost_iotlb *umem,
 825                              int log_all)
 826 {
 827         int i;
 828
 829         for (i = 0; i < d->nvqs; ++i) {
 830                 bool ok;
 831                 bool log;
 832
 833                 mutex_lock(&d->vqs[i]->mutex);
 834                 log = log_all || vhost_has_feature(d->vqs[i], VHOST_F_LOG_ALL);
 835                 /* If ring is inactive, will check when it's enabled. */
 836                 if (d->vqs[i]->private_data)
 837                         ok = vq_memory_access_ok(d->vqs[i]->log_base,
 838                                                  umem, log);
 839                 else
 840                         ok = true;
 841                 mutex_unlock(&d->vqs[i]->mutex);
 842                 if (!ok)
 843                         return false;
 844         }
 845         return true;
 846 }
 847
 848 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
 849                           struct iovec iov[], int iov_size, int access);
 850
 851 static int vhost_copy_to_user(struct vhost_virtqueue *vq, void __user *to,
 852                               const void *from, unsigned size)
 853 {
 854         int ret;
 855
 856         if (!vq->iotlb)
 857                 return __copy_to_user(to, from, size);
 858         else {
 859                 /* This function should be called after iotlb
 860                  * prefetch, which means we're sure that all vq
 861                  * could be access through iotlb. So -EAGAIN should
 862                  * not happen in this case.
 863                  */
 864                 struct iov_iter t;
 865                 void __user *uaddr = vhost_vq_meta_fetch(vq,
 866                                      (u64)(uintptr_t)to, size,
 867                                      VHOST_ADDR_USED);
 868
 869                 if (uaddr)
 870                         return __copy_to_user(uaddr, from, size);
 871
 872                 ret = translate_desc(vq, (u64)(uintptr_t)to, size, vq->iotlb_iov,
 873                                      ARRAY_SIZE(vq->iotlb_iov),
 874                                      VHOST_ACCESS_WO);
 875                 if (ret < 0)
 876                         goto out;
 877                 iov_iter_init(&t, ITER_DEST, vq->iotlb_iov, ret, size);
 878                 ret = copy_to_iter(from, size, &t);
 879                 if (ret == size)
 880                         ret = 0;
 881         }
 882 out:
 883         return ret;
 884 }
 885
 886 static int vhost_copy_from_user(struct vhost_virtqueue *vq, void *to,
 887                                 void __user *from, unsigned size)
 888 {
 889         int ret;
 890
 891         if (!vq->iotlb)
 892                 return __copy_from_user(to, from, size);
 893         else {
 894                 /* This function should be called after iotlb
 895                  * prefetch, which means we're sure that vq
 896                  * could be access through iotlb. So -EAGAIN should
 897                  * not happen in this case.
 898                  */
 899                 void __user *uaddr = vhost_vq_meta_fetch(vq,
 900                                      (u64)(uintptr_t)from, size,
 901                                      VHOST_ADDR_DESC);
 902                 struct iov_iter f;
 903
 904                 if (uaddr)
 905                         return __copy_from_user(to, uaddr, size);
 906
 907                 ret = translate_desc(vq, (u64)(uintptr_t)from, size, vq->iotlb_iov,
 908                                      ARRAY_SIZE(vq->iotlb_iov),
 909                                      VHOST_ACCESS_RO);
 910                 if (ret < 0) {
 911                         vq_err(vq, "IOTLB translation failure: uaddr "
 912                                "%p size 0x%llx\n", from,
 913                                (unsigned long long) size);
 914                         goto out;
 915                 }
 916                 iov_iter_init(&f, ITER_SOURCE, vq->iotlb_iov, ret, size);
 917                 ret = copy_from_iter(to, size, &f);
 918                 if (ret == size)
 919                         ret = 0;
 920         }
 921
 922 out:
 923         return ret;
 924 }
 925
 926 static void __user *__vhost_get_user_slow(struct vhost_virtqueue *vq,
 927                                           void __user *addr, unsigned int size,
 928                                           int type)
 929 {
 930         int ret;
 931
 932         ret = translate_desc(vq, (u64)(uintptr_t)addr, size, vq->iotlb_iov,
 933                              ARRAY_SIZE(vq->iotlb_iov),
 934                              VHOST_ACCESS_RO);
 935         if (ret < 0) {
 936                 vq_err(vq, "IOTLB translation failure: uaddr "
 937                         "%p size 0x%llx\n", addr,
 938                         (unsigned long long) size);
 939                 return NULL;
 940         }
 941
 942         if (ret != 1 || vq->iotlb_iov[0].iov_len != size) {
 943                 vq_err(vq, "Non atomic userspace memory access: uaddr "
 944                         "%p size 0x%llx\n", addr,
 945                         (unsigned long long) size);
 946                 return NULL;
 947         }
 948
 949         return vq->iotlb_iov[0].iov_base;
 950 }
 951
 952 /* This function should be called after iotlb
 953  * prefetch, which means we're sure that vq
 954  * could be access through iotlb. So -EAGAIN should
 955  * not happen in this case.
 956  */
 957 static inline void __user *__vhost_get_user(struct vhost_virtqueue *vq,
 958                                             void __user *addr, unsigned int size,
 959                                             int type)
 960 {
 961         void __user *uaddr = vhost_vq_meta_fetch(vq,
 962                              (u64)(uintptr_t)addr, size, type);
 963         if (uaddr)
 964                 return uaddr;
 965
 966         return __vhost_get_user_slow(vq, addr, size, type);
 967 }
 968
 969 #define vhost_put_user(vq, x, ptr)              \
 970 ({ \
 971         int ret; \
 972         if (!vq->iotlb) { \
 973                 ret = __put_user(x, ptr); \
 974         } else { \
 975                 __typeof__(ptr) to = \
 976                         (__typeof__(ptr)) __vhost_get_user(vq, ptr,     \
 977                                           sizeof(*ptr), VHOST_ADDR_USED); \
 978                 if (to != NULL) \
 979                         ret = __put_user(x, to); \
 980                 else \
 981                         ret = -EFAULT;  \
 982         } \
 983         ret; \
 984 })
 985
 986 static inline int vhost_put_avail_event(struct vhost_virtqueue *vq)
 987 {
 988         return vhost_put_user(vq, cpu_to_vhost16(vq, vq->avail_idx),
 989                               vhost_avail_event(vq));
 990 }
 991
 992 static inline int vhost_put_used(struct vhost_virtqueue *vq,
 993                                  struct vring_used_elem *head, int idx,
 994                                  int count)
 995 {
 996         return vhost_copy_to_user(vq, vq->used->ring + idx, head,
 997                                   count * sizeof(*head));
 998 }
 999
1000 static inline int vhost_put_used_flags(struct vhost_virtqueue *vq)
1001
1002 {
1003         return vhost_put_user(vq, cpu_to_vhost16(vq, vq->used_flags),
1004                               &vq->used->flags);
1005 }
1006
1007 static inline int vhost_put_used_idx(struct vhost_virtqueue *vq)
1008
1009 {
1010         return vhost_put_user(vq, cpu_to_vhost16(vq, vq->last_used_idx),
1011                               &vq->used->idx);
1012 }
1013
1014 #define vhost_get_user(vq, x, ptr, type)                \
1015 ({ \
1016         int ret; \
1017         if (!vq->iotlb) { \
1018                 ret = __get_user(x, ptr); \
1019         } else { \
1020                 __typeof__(ptr) from = \
1021                         (__typeof__(ptr)) __vhost_get_user(vq, ptr, \
1022                                                            sizeof(*ptr), \
1023                                                            type); \
1024                 if (from != NULL) \
1025                         ret = __get_user(x, from); \
1026                 else \
1027                         ret = -EFAULT; \
1028         } \
1029         ret; \
1030 })
1031
1032 #define vhost_get_avail(vq, x, ptr) \
1033         vhost_get_user(vq, x, ptr, VHOST_ADDR_AVAIL)
1034
1035 #define vhost_get_used(vq, x, ptr) \
1036         vhost_get_user(vq, x, ptr, VHOST_ADDR_USED)
1037
1038 static void vhost_dev_lock_vqs(struct vhost_dev *d)
1039 {
1040         int i = 0;
1041         for (i = 0; i < d->nvqs; ++i)
1042                 mutex_lock_nested(&d->vqs[i]->mutex, i);
1043 }
1044
1045 static void vhost_dev_unlock_vqs(struct vhost_dev *d)
1046 {
1047         int i = 0;
1048         for (i = 0; i < d->nvqs; ++i)
1049                 mutex_unlock(&d->vqs[i]->mutex);
1050 }
1051
1052 static inline int vhost_get_avail_idx(struct vhost_virtqueue *vq,
1053                                       __virtio16 *idx)
1054 {
1055         return vhost_get_avail(vq, *idx, &vq->avail->idx);
1056 }
1057
1058 static inline int vhost_get_avail_head(struct vhost_virtqueue *vq,
1059                                        __virtio16 *head, int idx)
1060 {
1061         return vhost_get_avail(vq, *head,
1062                                &vq->avail->ring[idx & (vq->num - 1)]);
1063 }
1064
1065 static inline int vhost_get_avail_flags(struct vhost_virtqueue *vq,
1066                                         __virtio16 *flags)
1067 {
1068         return vhost_get_avail(vq, *flags, &vq->avail->flags);
1069 }
1070
1071 static inline int vhost_get_used_event(struct vhost_virtqueue *vq,
1072                                        __virtio16 *event)
1073 {
1074         return vhost_get_avail(vq, *event, vhost_used_event(vq));
1075 }
1076
1077 static inline int vhost_get_used_idx(struct vhost_virtqueue *vq,
1078                                      __virtio16 *idx)
1079 {
1080         return vhost_get_used(vq, *idx, &vq->used->idx);
1081 }
1082
1083 static inline int vhost_get_desc(struct vhost_virtqueue *vq,
1084                                  struct vring_desc *desc, int idx)
1085 {
1086         return vhost_copy_from_user(vq, desc, vq->desc + idx, sizeof(*desc));
1087 }
1088
1089 static void vhost_iotlb_notify_vq(struct vhost_dev *d,
1090                                   struct vhost_iotlb_msg *msg)
1091 {
1092         struct vhost_msg_node *node, *n;
1093
1094         spin_lock(&d->iotlb_lock);
1095
1096         list_for_each_entry_safe(node, n, &d->pending_list, node) {
1097                 struct vhost_iotlb_msg *vq_msg = &node->msg.iotlb;
1098                 if (msg->iova <= vq_msg->iova &&
1099                     msg->iova + msg->size - 1 >= vq_msg->iova &&
1100                     vq_msg->type == VHOST_IOTLB_MISS) {
1101                         vhost_poll_queue(&node->vq->poll);
1102                         list_del(&node->node);
1103                         kfree(node);
1104                 }
1105         }
1106
1107         spin_unlock(&d->iotlb_lock);
1108 }
1109
1110 static bool umem_access_ok(u64 uaddr, u64 size, int access)
1111 {
1112         unsigned long a = uaddr;
1113
1114         /* Make sure 64 bit math will not overflow. */
1115         if (vhost_overflow(uaddr, size))
1116                 return false;
1117
1118         if ((access & VHOST_ACCESS_RO) &&
1119             !access_ok((void __user *)a, size))
1120                 return false;
1121         if ((access & VHOST_ACCESS_WO) &&
1122             !access_ok((void __user *)a, size))
1123                 return false;
1124         return true;
1125 }
1126
1127 static int vhost_process_iotlb_msg(struct vhost_dev *dev, u32 asid,
1128                                    struct vhost_iotlb_msg *msg)
1129 {
1130         int ret = 0;
1131
1132         if (asid != 0)
1133                 return -EINVAL;
1134
1135         mutex_lock(&dev->mutex);
1136         vhost_dev_lock_vqs(dev);
1137         switch (msg->type) {
1138         case VHOST_IOTLB_UPDATE:
1139                 if (!dev->iotlb) {
1140                         ret = -EFAULT;
1141                         break;
1142                 }
1143                 if (!umem_access_ok(msg->uaddr, msg->size, msg->perm)) {
1144                         ret = -EFAULT;
1145                         break;
1146                 }
1147                 vhost_vq_meta_reset(dev);
1148                 if (vhost_iotlb_add_range(dev->iotlb, msg->iova,
1149                                           msg->iova + msg->size - 1,
1150                                           msg->uaddr, msg->perm)) {
1151                         ret = -ENOMEM;
1152                         break;
1153                 }
1154                 vhost_iotlb_notify_vq(dev, msg);
1155                 break;
1156         case VHOST_IOTLB_INVALIDATE:
1157                 if (!dev->iotlb) {
1158                         ret = -EFAULT;
1159                         break;
1160                 }
1161                 vhost_vq_meta_reset(dev);
1162                 vhost_iotlb_del_range(dev->iotlb, msg->iova,
1163                                       msg->iova + msg->size - 1);
1164                 break;
1165         default:
1166                 ret = -EINVAL;
1167                 break;
1168         }
1169
1170         vhost_dev_unlock_vqs(dev);
1171         mutex_unlock(&dev->mutex);
1172
1173         return ret;
1174 }
1175 ssize_t vhost_chr_write_iter(struct vhost_dev *dev,
1176                              struct iov_iter *from)
1177 {
1178         struct vhost_iotlb_msg msg;
1179         size_t offset;
1180         int type, ret;
1181         u32 asid = 0;
1182
1183         ret = copy_from_iter(&type, sizeof(type), from);
1184         if (ret != sizeof(type)) {
1185                 ret = -EINVAL;
1186                 goto done;
1187         }
1188
1189         switch (type) {
1190         case VHOST_IOTLB_MSG:
1191                 /* There maybe a hole after type for V1 message type,
1192                  * so skip it here.
1193                  */
1194                 offset = offsetof(struct vhost_msg, iotlb) - sizeof(int);
1195                 break;
1196         case VHOST_IOTLB_MSG_V2:
1197                 if (vhost_backend_has_feature(dev->vqs[0],
1198                                               VHOST_BACKEND_F_IOTLB_ASID)) {
1199                         ret = copy_from_iter(&asid, sizeof(asid), from);
1200                         if (ret != sizeof(asid)) {
1201                                 ret = -EINVAL;
1202                                 goto done;
1203                         }
1204                         offset = 0;
1205                 } else
1206                         offset = sizeof(__u32);
1207                 break;
1208         default:
1209                 ret = -EINVAL;
1210                 goto done;
1211         }
1212
1213         iov_iter_advance(from, offset);
1214         ret = copy_from_iter(&msg, sizeof(msg), from);
1215         if (ret != sizeof(msg)) {
1216                 ret = -EINVAL;
1217                 goto done;
1218         }
1219
1220         if ((msg.type == VHOST_IOTLB_UPDATE ||
1221              msg.type == VHOST_IOTLB_INVALIDATE) &&
1222              msg.size == 0) {
1223                 ret = -EINVAL;
1224                 goto done;
1225         }
1226
1227         if (dev->msg_handler)
1228                 ret = dev->msg_handler(dev, asid, &msg);
1229         else
1230                 ret = vhost_process_iotlb_msg(dev, asid, &msg);
1231         if (ret) {
1232                 ret = -EFAULT;
1233                 goto done;
1234         }
1235
1236         ret = (type == VHOST_IOTLB_MSG) ? sizeof(struct vhost_msg) :
1237               sizeof(struct vhost_msg_v2);
1238 done:
1239         return ret;
1240 }
1241 EXPORT_SYMBOL(vhost_chr_write_iter);
1242
1243 __poll_t vhost_chr_poll(struct file *file, struct vhost_dev *dev,
1244                             poll_table *wait)
1245 {
1246         __poll_t mask = 0;
1247
1248         poll_wait(file, &dev->wait, wait);
1249
1250         if (!list_empty(&dev->read_list))
1251                 mask |= EPOLLIN | EPOLLRDNORM;
1252
1253         return mask;
1254 }
1255 EXPORT_SYMBOL(vhost_chr_poll);
1256
1257 ssize_t vhost_chr_read_iter(struct vhost_dev *dev, struct iov_iter *to,
1258                             int noblock)
1259 {
1260         DEFINE_WAIT(wait);
1261         struct vhost_msg_node *node;
1262         ssize_t ret = 0;
1263         unsigned size = sizeof(struct vhost_msg);
1264
1265         if (iov_iter_count(to) < size)
1266                 return 0;
1267
1268         while (1) {
1269                 if (!noblock)
1270                         prepare_to_wait(&dev->wait, &wait,
1271                                         TASK_INTERRUPTIBLE);
1272
1273                 node = vhost_dequeue_msg(dev, &dev->read_list);
1274                 if (node)
1275                         break;
1276                 if (noblock) {
1277                         ret = -EAGAIN;
1278                         break;
1279                 }
1280                 if (signal_pending(current)) {
1281                         ret = -ERESTARTSYS;
1282                         break;
1283                 }
1284                 if (!dev->iotlb) {
1285                         ret = -EBADFD;
1286                         break;
1287                 }
1288
1289                 schedule();
1290         }
1291
1292         if (!noblock)
1293                 finish_wait(&dev->wait, &wait);
1294
1295         if (node) {
1296                 struct vhost_iotlb_msg *msg;
1297                 void *start = &node->msg;
1298
1299                 switch (node->msg.type) {
1300                 case VHOST_IOTLB_MSG:
1301                         size = sizeof(node->msg);
1302                         msg = &node->msg.iotlb;
1303                         break;
1304                 case VHOST_IOTLB_MSG_V2:
1305                         size = sizeof(node->msg_v2);
1306                         msg = &node->msg_v2.iotlb;
1307                         break;
1308                 default:
1309                         BUG();
1310                         break;
1311                 }
1312
1313                 ret = copy_to_iter(start, size, to);
1314                 if (ret != size || msg->type != VHOST_IOTLB_MISS) {
1315                         kfree(node);
1316                         return ret;
1317                 }
1318                 vhost_enqueue_msg(dev, &dev->pending_list, node);
1319         }
1320
1321         return ret;
1322 }
1323 EXPORT_SYMBOL_GPL(vhost_chr_read_iter);
1324
1325 static int vhost_iotlb_miss(struct vhost_virtqueue *vq, u64 iova, int access)
1326 {
1327         struct vhost_dev *dev = vq->dev;
1328         struct vhost_msg_node *node;
1329         struct vhost_iotlb_msg *msg;
1330         bool v2 = vhost_backend_has_feature(vq, VHOST_BACKEND_F_IOTLB_MSG_V2);
1331
1332         node = vhost_new_msg(vq, v2 ? VHOST_IOTLB_MSG_V2 : VHOST_IOTLB_MSG);
1333         if (!node)
1334                 return -ENOMEM;
1335
1336         if (v2) {
1337                 node->msg_v2.type = VHOST_IOTLB_MSG_V2;
1338                 msg = &node->msg_v2.iotlb;
1339         } else {
1340                 msg = &node->msg.iotlb;
1341         }
1342
1343         msg->type = VHOST_IOTLB_MISS;
1344         msg->iova = iova;
1345         msg->perm = access;
1346
1347         vhost_enqueue_msg(dev, &dev->read_list, node);
1348
1349         return 0;
1350 }
1351
1352 static bool vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
1353                          vring_desc_t __user *desc,
1354                          vring_avail_t __user *avail,
1355                          vring_used_t __user *used)
1356
1357 {
1358         /* If an IOTLB device is present, the vring addresses are
1359          * GIOVAs. Access validation occurs at prefetch time. */
1360         if (vq->iotlb)
1361                 return true;
1362
1363         return access_ok(desc, vhost_get_desc_size(vq, num)) &&
1364                access_ok(avail, vhost_get_avail_size(vq, num)) &&
1365                access_ok(used, vhost_get_used_size(vq, num));
1366 }
1367
1368 static void vhost_vq_meta_update(struct vhost_virtqueue *vq,
1369                                  const struct vhost_iotlb_map *map,
1370                                  int type)
1371 {
1372         int access = (type == VHOST_ADDR_USED) ?
1373                      VHOST_ACCESS_WO : VHOST_ACCESS_RO;
1374
1375         if (likely(map->perm & access))
1376                 vq->meta_iotlb[type] = map;
1377 }
1378
1379 static bool iotlb_access_ok(struct vhost_virtqueue *vq,
1380                             int access, u64 addr, u64 len, int type)
1381 {
1382         const struct vhost_iotlb_map *map;
1383         struct vhost_iotlb *umem = vq->iotlb;
1384         u64 s = 0, size, orig_addr = addr, last = addr + len - 1;
1385
1386         if (vhost_vq_meta_fetch(vq, addr, len, type))
1387                 return true;
1388
1389         while (len > s) {
1390                 map = vhost_iotlb_itree_first(umem, addr, last);
1391                 if (map == NULL || map->start > addr) {
1392                         vhost_iotlb_miss(vq, addr, access);
1393                         return false;
1394                 } else if (!(map->perm & access)) {
1395                         /* Report the possible access violation by
1396                          * request another translation from userspace.
1397                          */
1398                         return false;
1399                 }
1400
1401                 size = map->size - addr + map->start;
1402
1403                 if (orig_addr == addr && size >= len)
1404                         vhost_vq_meta_update(vq, map, type);
1405
1406                 s += size;
1407                 addr += size;
1408         }
1409
1410         return true;
1411 }
1412
1413 int vq_meta_prefetch(struct vhost_virtqueue *vq)
1414 {
1415         unsigned int num = vq->num;
1416
1417         if (!vq->iotlb)
1418                 return 1;
1419
1420         return iotlb_access_ok(vq, VHOST_MAP_RO, (u64)(uintptr_t)vq->desc,
1421                                vhost_get_desc_size(vq, num), VHOST_ADDR_DESC) &&
1422                iotlb_access_ok(vq, VHOST_MAP_RO, (u64)(uintptr_t)vq->avail,
1423                                vhost_get_avail_size(vq, num),
1424                                VHOST_ADDR_AVAIL) &&
1425                iotlb_access_ok(vq, VHOST_MAP_WO, (u64)(uintptr_t)vq->used,
1426                                vhost_get_used_size(vq, num), VHOST_ADDR_USED);
1427 }
1428 EXPORT_SYMBOL_GPL(vq_meta_prefetch);
1429
1430 /* Can we log writes? */
1431 /* Caller should have device mutex but not vq mutex */
1432 bool vhost_log_access_ok(struct vhost_dev *dev)
1433 {
1434         return memory_access_ok(dev, dev->umem, 1);
1435 }
1436 EXPORT_SYMBOL_GPL(vhost_log_access_ok);
1437
1438 static bool vq_log_used_access_ok(struct vhost_virtqueue *vq,
1439                                   void __user *log_base,
1440                                   bool log_used,
1441                                   u64 log_addr)
1442 {
1443         /* If an IOTLB device is present, log_addr is a GIOVA that
1444          * will never be logged by log_used(). */
1445         if (vq->iotlb)
1446                 return true;
1447
1448         return !log_used || log_access_ok(log_base, log_addr,
1449                                           vhost_get_used_size(vq, vq->num));
1450 }
1451
1452 /* Verify access for write logging. */
1453 /* Caller should have vq mutex and device mutex */
1454 static bool vq_log_access_ok(struct vhost_virtqueue *vq,
1455                              void __user *log_base)
1456 {
1457         return vq_memory_access_ok(log_base, vq->umem,
1458                                    vhost_has_feature(vq, VHOST_F_LOG_ALL)) &&
1459                 vq_log_used_access_ok(vq, log_base, vq->log_used, vq->log_addr);
1460 }
1461
1462 /* Can we start vq? */
1463 /* Caller should have vq mutex and device mutex */
1464 bool vhost_vq_access_ok(struct vhost_virtqueue *vq)
1465 {
1466         if (!vq_log_access_ok(vq, vq->log_base))
1467                 return false;
1468
1469         return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used);
1470 }
1471 EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
1472
1473 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
1474 {
1475         struct vhost_memory mem, *newmem;
1476         struct vhost_memory_region *region;
1477         struct vhost_iotlb *newumem, *oldumem;
1478         unsigned long size = offsetof(struct vhost_memory, regions);
1479         int i;
1480
1481         if (copy_from_user(&mem, m, size))
1482                 return -EFAULT;
1483         if (mem.padding)
1484                 return -EOPNOTSUPP;
1485         if (mem.nregions > max_mem_regions)
1486                 return -E2BIG;
1487         newmem = kvzalloc(struct_size(newmem, regions, mem.nregions),
1488                         GFP_KERNEL);
1489         if (!newmem)
1490                 return -ENOMEM;
1491
1492         memcpy(newmem, &mem, size);
1493         if (copy_from_user(newmem->regions, m->regions,
1494                            flex_array_size(newmem, regions, mem.nregions))) {
1495                 kvfree(newmem);
1496                 return -EFAULT;
1497         }
1498
1499         newumem = iotlb_alloc();
1500         if (!newumem) {
1501                 kvfree(newmem);
1502                 return -ENOMEM;
1503         }
1504
1505         for (region = newmem->regions;
1506              region < newmem->regions + mem.nregions;
1507              region++) {
1508                 if (vhost_iotlb_add_range(newumem,
1509                                           region->guest_phys_addr,
1510                                           region->guest_phys_addr +
1511                                           region->memory_size - 1,
1512                                           region->userspace_addr,
1513                                           VHOST_MAP_RW))
1514                         goto err;
1515         }
1516
1517         if (!memory_access_ok(d, newumem, 0))
1518                 goto err;
1519
1520         oldumem = d->umem;
1521         d->umem = newumem;
1522
1523         /* All memory accesses are done under some VQ mutex. */
1524         for (i = 0; i < d->nvqs; ++i) {
1525                 mutex_lock(&d->vqs[i]->mutex);
1526                 d->vqs[i]->umem = newumem;
1527                 mutex_unlock(&d->vqs[i]->mutex);
1528         }
1529
1530         kvfree(newmem);
1531         vhost_iotlb_free(oldumem);
1532         return 0;
1533
1534 err:
1535         vhost_iotlb_free(newumem);
1536         kvfree(newmem);
1537         return -EFAULT;
1538 }
1539
1540 static long vhost_vring_set_num(struct vhost_dev *d,
1541                                 struct vhost_virtqueue *vq,
1542                                 void __user *argp)
1543 {
1544         struct vhost_vring_state s;
1545
1546         /* Resizing ring with an active backend?
1547          * You don't want to do that. */
1548         if (vq->private_data)
1549                 return -EBUSY;
1550
1551         if (copy_from_user(&s, argp, sizeof s))
1552                 return -EFAULT;
1553
1554         if (!s.num || s.num > 0xffff || (s.num & (s.num - 1)))
1555                 return -EINVAL;
1556         vq->num = s.num;
1557
1558         return 0;
1559 }
1560
1561 static long vhost_vring_set_addr(struct vhost_dev *d,
1562                                  struct vhost_virtqueue *vq,
1563                                  void __user *argp)
1564 {
1565         struct vhost_vring_addr a;
1566
1567         if (copy_from_user(&a, argp, sizeof a))
1568                 return -EFAULT;
1569         if (a.flags & ~(0x1 << VHOST_VRING_F_LOG))
1570                 return -EOPNOTSUPP;
1571
1572         /* For 32bit, verify that the top 32bits of the user
1573            data are set to zero. */
1574         if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr ||
1575             (u64)(unsigned long)a.used_user_addr != a.used_user_addr ||
1576             (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr)
1577                 return -EFAULT;
1578
1579         /* Make sure it's safe to cast pointers to vring types. */
1580         BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE);
1581         BUILD_BUG_ON(__alignof__ *vq->used > VRING_USED_ALIGN_SIZE);
1582         if ((a.avail_user_addr & (VRING_AVAIL_ALIGN_SIZE - 1)) ||
1583             (a.used_user_addr & (VRING_USED_ALIGN_SIZE - 1)) ||
1584             (a.log_guest_addr & (VRING_USED_ALIGN_SIZE - 1)))
1585                 return -EINVAL;
1586
1587         /* We only verify access here if backend is configured.
1588          * If it is not, we don't as size might not have been setup.
1589          * We will verify when backend is configured. */
1590         if (vq->private_data) {
1591                 if (!vq_access_ok(vq, vq->num,
1592                         (void __user *)(unsigned long)a.desc_user_addr,
1593                         (void __user *)(unsigned long)a.avail_user_addr,
1594                         (void __user *)(unsigned long)a.used_user_addr))
1595                         return -EINVAL;
1596
1597                 /* Also validate log access for used ring if enabled. */
1598                 if (!vq_log_used_access_ok(vq, vq->log_base,
1599                                 a.flags & (0x1 << VHOST_VRING_F_LOG),
1600                                 a.log_guest_addr))
1601                         return -EINVAL;
1602         }
1603
1604         vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
1605         vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
1606         vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
1607         vq->log_addr = a.log_guest_addr;
1608         vq->used = (void __user *)(unsigned long)a.used_user_addr;
1609
1610         return 0;
1611 }
1612
1613 static long vhost_vring_set_num_addr(struct vhost_dev *d,
1614                                      struct vhost_virtqueue *vq,
1615                                      unsigned int ioctl,
1616                                      void __user *argp)
1617 {
1618         long r;
1619
1620         mutex_lock(&vq->mutex);
1621
1622         switch (ioctl) {
1623         case VHOST_SET_VRING_NUM:
1624                 r = vhost_vring_set_num(d, vq, argp);
1625                 break;
1626         case VHOST_SET_VRING_ADDR:
1627                 r = vhost_vring_set_addr(d, vq, argp);
1628                 break;
1629         default:
1630                 BUG();
1631         }
1632
1633         mutex_unlock(&vq->mutex);
1634
1635         return r;
1636 }
1637 long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
1638 {
1639         struct file *eventfp, *filep = NULL;
1640         bool pollstart = false, pollstop = false;
1641         struct eventfd_ctx *ctx = NULL;
1642         struct vhost_virtqueue *vq;
1643         struct vhost_vring_state s;
1644         struct vhost_vring_file f;
1645         u32 idx;
1646         long r;
1647
1648         r = vhost_get_vq_from_user(d, argp, &vq, &idx);
1649         if (r < 0)
1650                 return r;
1651
1652         if (ioctl == VHOST_SET_VRING_NUM ||
1653             ioctl == VHOST_SET_VRING_ADDR) {
1654                 return vhost_vring_set_num_addr(d, vq, ioctl, argp);
1655         }
1656
1657         mutex_lock(&vq->mutex);
1658
1659         switch (ioctl) {
1660         case VHOST_SET_VRING_BASE:
1661                 /* Moving base with an active backend?
1662                  * You don't want to do that. */
1663                 if (vq->private_data) {
1664                         r = -EBUSY;
1665                         break;
1666                 }
1667                 if (copy_from_user(&s, argp, sizeof s)) {
1668                         r = -EFAULT;
1669                         break;
1670                 }
1671                 if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) {
1672                         vq->last_avail_idx = s.num & 0xffff;
1673                         vq->last_used_idx = (s.num >> 16) & 0xffff;
1674                 } else {
1675                         if (s.num > 0xffff) {
1676                                 r = -EINVAL;
1677                                 break;
1678                         }
1679                         vq->last_avail_idx = s.num;
1680                 }
1681                 /* Forget the cached index value. */
1682                 vq->avail_idx = vq->last_avail_idx;
1683                 break;
1684         case VHOST_GET_VRING_BASE:
1685                 s.index = idx;
1686                 if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED))
1687                         s.num = (u32)vq->last_avail_idx | ((u32)vq->last_used_idx << 16);
1688                 else
1689                         s.num = vq->last_avail_idx;
1690                 if (copy_to_user(argp, &s, sizeof s))
1691                         r = -EFAULT;
1692                 break;
1693         case VHOST_SET_VRING_KICK:
1694                 if (copy_from_user(&f, argp, sizeof f)) {
1695                         r = -EFAULT;
1696                         break;
1697                 }
1698                 eventfp = f.fd == VHOST_FILE_UNBIND ? NULL : eventfd_fget(f.fd);
1699                 if (IS_ERR(eventfp)) {
1700                         r = PTR_ERR(eventfp);
1701                         break;
1702                 }
1703                 if (eventfp != vq->kick) {
1704                         pollstop = (filep = vq->kick) != NULL;
1705                         pollstart = (vq->kick = eventfp) != NULL;
1706                 } else
1707                         filep = eventfp;
1708                 break;
1709         case VHOST_SET_VRING_CALL:
1710                 if (copy_from_user(&f, argp, sizeof f)) {
1711                         r = -EFAULT;
1712                         break;
1713                 }
1714                 ctx = f.fd == VHOST_FILE_UNBIND ? NULL : eventfd_ctx_fdget(f.fd);
1715                 if (IS_ERR(ctx)) {
1716                         r = PTR_ERR(ctx);
1717                         break;
1718                 }
1719
1720                 swap(ctx, vq->call_ctx.ctx);
1721                 break;
1722         case VHOST_SET_VRING_ERR:
1723                 if (copy_from_user(&f, argp, sizeof f)) {
1724                         r = -EFAULT;
1725                         break;
1726                 }
1727                 ctx = f.fd == VHOST_FILE_UNBIND ? NULL : eventfd_ctx_fdget(f.fd);
1728                 if (IS_ERR(ctx)) {
1729                         r = PTR_ERR(ctx);
1730                         break;
1731                 }
1732                 swap(ctx, vq->error_ctx);
1733                 break;
1734         case VHOST_SET_VRING_ENDIAN:
1735                 r = vhost_set_vring_endian(vq, argp);
1736                 break;
1737         case VHOST_GET_VRING_ENDIAN:
1738                 r = vhost_get_vring_endian(vq, idx, argp);
1739                 break;
1740         case VHOST_SET_VRING_BUSYLOOP_TIMEOUT:
1741                 if (copy_from_user(&s, argp, sizeof(s))) {
1742                         r = -EFAULT;
1743                         break;
1744                 }
1745                 vq->busyloop_timeout = s.num;
1746                 break;
1747         case VHOST_GET_VRING_BUSYLOOP_TIMEOUT:
1748                 s.index = idx;
1749                 s.num = vq->busyloop_timeout;
1750                 if (copy_to_user(argp, &s, sizeof(s)))
1751                         r = -EFAULT;
1752                 break;
1753         default:
1754                 r = -ENOIOCTLCMD;
1755         }
1756
1757         if (pollstop && vq->handle_kick)
1758                 vhost_poll_stop(&vq->poll);
1759
1760         if (!IS_ERR_OR_NULL(ctx))
1761                 eventfd_ctx_put(ctx);
1762         if (filep)
1763                 fput(filep);
1764
1765         if (pollstart && vq->handle_kick)
1766                 r = vhost_poll_start(&vq->poll, vq->kick);
1767
1768         mutex_unlock(&vq->mutex);
1769
1770         if (pollstop && vq->handle_kick)
1771                 vhost_dev_flush(vq->poll.dev);
1772         return r;
1773 }
1774 EXPORT_SYMBOL_GPL(vhost_vring_ioctl);
1775
1776 int vhost_init_device_iotlb(struct vhost_dev *d)
1777 {
1778         struct vhost_iotlb *niotlb, *oiotlb;
1779         int i;
1780
1781         niotlb = iotlb_alloc();
1782         if (!niotlb)
1783                 return -ENOMEM;
1784
1785         oiotlb = d->iotlb;
1786         d->iotlb = niotlb;
1787
1788         for (i = 0; i < d->nvqs; ++i) {
1789                 struct vhost_virtqueue *vq = d->vqs[i];
1790
1791                 mutex_lock(&vq->mutex);
1792                 vq->iotlb = niotlb;
1793                 __vhost_vq_meta_reset(vq);
1794                 mutex_unlock(&vq->mutex);
1795         }
1796
1797         vhost_iotlb_free(oiotlb);
1798
1799         return 0;
1800 }
1801 EXPORT_SYMBOL_GPL(vhost_init_device_iotlb);
1802
1803 /* Caller must have device mutex */
1804 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
1805 {
1806         struct eventfd_ctx *ctx;
1807         u64 p;
1808         long r;
1809         int i, fd;
1810
1811         /* If you are not the owner, you can become one */
1812         if (ioctl == VHOST_SET_OWNER) {
1813                 r = vhost_dev_set_owner(d);
1814                 goto done;
1815         }
1816
1817         /* You must be the owner to do anything else */
1818         r = vhost_dev_check_owner(d);
1819         if (r)
1820                 goto done;
1821
1822         switch (ioctl) {
1823         case VHOST_SET_MEM_TABLE:
1824                 r = vhost_set_memory(d, argp);
1825                 break;
1826         case VHOST_SET_LOG_BASE:
1827                 if (copy_from_user(&p, argp, sizeof p)) {
1828                         r = -EFAULT;
1829                         break;
1830                 }
1831                 if ((u64)(unsigned long)p != p) {
1832                         r = -EFAULT;
1833                         break;
1834                 }
1835                 for (i = 0; i < d->nvqs; ++i) {
1836                         struct vhost_virtqueue *vq;
1837                         void __user *base = (void __user *)(unsigned long)p;
1838                         vq = d->vqs[i];
1839                         mutex_lock(&vq->mutex);
1840                         /* If ring is inactive, will check when it's enabled. */
1841                         if (vq->private_data && !vq_log_access_ok(vq, base))
1842                                 r = -EFAULT;
1843                         else
1844                                 vq->log_base = base;
1845                         mutex_unlock(&vq->mutex);
1846                 }
1847                 break;
1848         case VHOST_SET_LOG_FD:
1849                 r = get_user(fd, (int __user *)argp);
1850                 if (r < 0)
1851                         break;
1852                 ctx = fd == VHOST_FILE_UNBIND ? NULL : eventfd_ctx_fdget(fd);
1853                 if (IS_ERR(ctx)) {
1854                         r = PTR_ERR(ctx);
1855                         break;
1856                 }
1857                 swap(ctx, d->log_ctx);
1858                 for (i = 0; i < d->nvqs; ++i) {
1859                         mutex_lock(&d->vqs[i]->mutex);
1860                         d->vqs[i]->log_ctx = d->log_ctx;
1861                         mutex_unlock(&d->vqs[i]->mutex);
1862                 }
1863                 if (ctx)
1864                         eventfd_ctx_put(ctx);
1865                 break;
1866         default:
1867                 r = -ENOIOCTLCMD;
1868                 break;
1869         }
1870 done:
1871         return r;
1872 }
1873 EXPORT_SYMBOL_GPL(vhost_dev_ioctl);
1874
1875 /* TODO: This is really inefficient.  We need something like get_user()
1876  * (instruction directly accesses the data, with an exception table entry
1877  * returning -EFAULT). See Documentation/arch/x86/exception-tables.rst.
1878  */
1879 static int set_bit_to_user(int nr, void __user *addr)
1880 {
1881         unsigned long log = (unsigned long)addr;
1882         struct page *page;
1883         void *base;
1884         int bit = nr + (log % PAGE_SIZE) * 8;
1885         int r;
1886
1887         r = pin_user_pages_fast(log, 1, FOLL_WRITE, &page);
1888         if (r < 0)
1889                 return r;
1890         BUG_ON(r != 1);
1891         base = kmap_atomic(page);
1892         set_bit(bit, base);
1893         kunmap_atomic(base);
1894         unpin_user_pages_dirty_lock(&page, 1, true);
1895         return 0;
1896 }
1897
1898 static int log_write(void __user *log_base,
1899                      u64 write_address, u64 write_length)
1900 {
1901         u64 write_page = write_address / VHOST_PAGE_SIZE;
1902         int r;
1903
1904         if (!write_length)
1905                 return 0;
1906         write_length += write_address % VHOST_PAGE_SIZE;
1907         for (;;) {
1908                 u64 base = (u64)(unsigned long)log_base;
1909                 u64 log = base + write_page / 8;
1910                 int bit = write_page % 8;
1911                 if ((u64)(unsigned long)log != log)
1912                         return -EFAULT;
1913                 r = set_bit_to_user(bit, (void __user *)(unsigned long)log);
1914                 if (r < 0)
1915                         return r;
1916                 if (write_length <= VHOST_PAGE_SIZE)
1917                         break;
1918                 write_length -= VHOST_PAGE_SIZE;
1919                 write_page += 1;
1920         }
1921         return r;
1922 }
1923
1924 static int log_write_hva(struct vhost_virtqueue *vq, u64 hva, u64 len)
1925 {
1926         struct vhost_iotlb *umem = vq->umem;
1927         struct vhost_iotlb_map *u;
1928         u64 start, end, l, min;
1929         int r;
1930         bool hit = false;
1931
1932         while (len) {
1933                 min = len;
1934                 /* More than one GPAs can be mapped into a single HVA. So
1935                  * iterate all possible umems here to be safe.
1936                  */
1937                 list_for_each_entry(u, &umem->list, link) {
1938                         if (u->addr > hva - 1 + len ||
1939                             u->addr - 1 + u->size < hva)
1940                                 continue;
1941                         start = max(u->addr, hva);
1942                         end = min(u->addr - 1 + u->size, hva - 1 + len);
1943                         l = end - start + 1;
1944                         r = log_write(vq->log_base,
1945                                       u->start + start - u->addr,
1946                                       l);
1947                         if (r < 0)
1948                                 return r;
1949                         hit = true;
1950                         min = min(l, min);
1951                 }
1952
1953                 if (!hit)
1954                         return -EFAULT;
1955
1956                 len -= min;
1957                 hva += min;
1958         }
1959
1960         return 0;
1961 }
1962
1963 static int log_used(struct vhost_virtqueue *vq, u64 used_offset, u64 len)
1964 {
1965         struct iovec *iov = vq->log_iov;
1966         int i, ret;
1967
1968         if (!vq->iotlb)
1969                 return log_write(vq->log_base, vq->log_addr + used_offset, len);
1970
1971         ret = translate_desc(vq, (uintptr_t)vq->used + used_offset,
1972                              len, iov, 64, VHOST_ACCESS_WO);
1973         if (ret < 0)
1974                 return ret;
1975
1976         for (i = 0; i < ret; i++) {
1977                 ret = log_write_hva(vq, (uintptr_t)iov[i].iov_base,
1978                                     iov[i].iov_len);
1979                 if (ret)
1980                         return ret;
1981         }
1982
1983         return 0;
1984 }
1985
1986 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
1987                     unsigned int log_num, u64 len, struct iovec *iov, int count)
1988 {
1989         int i, r;
1990
1991         /* Make sure data written is seen before log. */
1992         smp_wmb();
1993
1994         if (vq->iotlb) {
1995                 for (i = 0; i < count; i++) {
1996                         r = log_write_hva(vq, (uintptr_t)iov[i].iov_base,
1997                                           iov[i].iov_len);
1998                         if (r < 0)
1999                                 return r;
2000                 }
2001                 return 0;
2002         }
2003
2004         for (i = 0; i < log_num; ++i) {
2005                 u64 l = min(log[i].len, len);
2006                 r = log_write(vq->log_base, log[i].addr, l);
2007                 if (r < 0)
2008                         return r;
2009                 len -= l;
2010                 if (!len) {
2011                         if (vq->log_ctx)
2012                                 eventfd_signal(vq->log_ctx, 1);
2013                         return 0;
2014                 }
2015         }
2016         /* Length written exceeds what we have stored. This is a bug. */
2017         BUG();
2018         return 0;
2019 }
2020 EXPORT_SYMBOL_GPL(vhost_log_write);
2021
2022 static int vhost_update_used_flags(struct vhost_virtqueue *vq)
2023 {
2024         void __user *used;
2025         if (vhost_put_used_flags(vq))
2026                 return -EFAULT;
2027         if (unlikely(vq->log_used)) {
2028                 /* Make sure the flag is seen before log. */
2029                 smp_wmb();
2030                 /* Log used flag write. */
2031                 used = &vq->used->flags;
2032                 log_used(vq, (used - (void __user *)vq->used),
2033                          sizeof vq->used->flags);
2034                 if (vq->log_ctx)
2035                         eventfd_signal(vq->log_ctx, 1);
2036         }
2037         return 0;
2038 }
2039
2040 static int vhost_update_avail_event(struct vhost_virtqueue *vq)
2041 {
2042         if (vhost_put_avail_event(vq))
2043                 return -EFAULT;
2044         if (unlikely(vq->log_used)) {
2045                 void __user *used;
2046                 /* Make sure the event is seen before log. */
2047                 smp_wmb();
2048                 /* Log avail event write */
2049                 used = vhost_avail_event(vq);
2050                 log_used(vq, (used - (void __user *)vq->used),
2051                          sizeof *vhost_avail_event(vq));
2052                 if (vq->log_ctx)
2053                         eventfd_signal(vq->log_ctx, 1);
2054         }
2055         return 0;
2056 }
2057
2058 int vhost_vq_init_access(struct vhost_virtqueue *vq)
2059 {
2060         __virtio16 last_used_idx;
2061         int r;
2062         bool is_le = vq->is_le;
2063
2064         if (!vq->private_data)
2065                 return 0;
2066
2067         vhost_init_is_le(vq);
2068
2069         r = vhost_update_used_flags(vq);
2070         if (r)
2071                 goto err;
2072         vq->signalled_used_valid = false;
2073         if (!vq->iotlb &&
2074             !access_ok(&vq->used->idx, sizeof vq->used->idx)) {
2075                 r = -EFAULT;
2076                 goto err;
2077         }
2078         r = vhost_get_used_idx(vq, &last_used_idx);
2079         if (r) {
2080                 vq_err(vq, "Can't access used idx at %p\n",
2081                        &vq->used->idx);
2082                 goto err;
2083         }
2084         vq->last_used_idx = vhost16_to_cpu(vq, last_used_idx);
2085         return 0;
2086
2087 err:
2088         vq->is_le = is_le;
2089         return r;
2090 }
2091 EXPORT_SYMBOL_GPL(vhost_vq_init_access);
2092
2093 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
2094                           struct iovec iov[], int iov_size, int access)
2095 {
2096         const struct vhost_iotlb_map *map;
2097         struct vhost_dev *dev = vq->dev;
2098         struct vhost_iotlb *umem = dev->iotlb ? dev->iotlb : dev->umem;
2099         struct iovec *_iov;
2100         u64 s = 0, last = addr + len - 1;
2101         int ret = 0;
2102
2103         while ((u64)len > s) {
2104                 u64 size;
2105                 if (unlikely(ret >= iov_size)) {
2106                         ret = -ENOBUFS;
2107                         break;
2108                 }
2109
2110                 map = vhost_iotlb_itree_first(umem, addr, last);
2111                 if (map == NULL || map->start > addr) {
2112                         if (umem != dev->iotlb) {
2113                                 ret = -EFAULT;
2114                                 break;
2115                         }
2116                         ret = -EAGAIN;
2117                         break;
2118                 } else if (!(map->perm & access)) {
2119                         ret = -EPERM;
2120                         break;
2121                 }
2122
2123                 _iov = iov + ret;
2124                 size = map->size - addr + map->start;
2125                 _iov->iov_len = min((u64)len - s, size);
2126                 _iov->iov_base = (void __user *)(unsigned long)
2127                                  (map->addr + addr - map->start);
2128                 s += size;
2129                 addr += size;
2130                 ++ret;
2131         }
2132
2133         if (ret == -EAGAIN)
2134                 vhost_iotlb_miss(vq, addr, access);
2135         return ret;
2136 }
2137
2138 /* Each buffer in the virtqueues is actually a chain of descriptors.  This
2139  * function returns the next descriptor in the chain,
2140  * or -1U if we're at the end. */
2141 static unsigned next_desc(struct vhost_virtqueue *vq, struct vring_desc *desc)
2142 {
2143         unsigned int next;
2144
2145         /* If this descriptor says it doesn't chain, we're done. */
2146         if (!(desc->flags & cpu_to_vhost16(vq, VRING_DESC_F_NEXT)))
2147                 return -1U;
2148
2149         /* Check they're not leading us off end of descriptors. */
2150         next = vhost16_to_cpu(vq, READ_ONCE(desc->next));
2151         return next;
2152 }
2153
2154 static int get_indirect(struct vhost_virtqueue *vq,
2155                         struct iovec iov[], unsigned int iov_size,
2156                         unsigned int *out_num, unsigned int *in_num,
2157                         struct vhost_log *log, unsigned int *log_num,
2158                         struct vring_desc *indirect)
2159 {
2160         struct vring_desc desc;
2161         unsigned int i = 0, count, found = 0;
2162         u32 len = vhost32_to_cpu(vq, indirect->len);
2163         struct iov_iter from;
2164         int ret, access;
2165
2166         /* Sanity check */
2167         if (unlikely(len % sizeof desc)) {
2168                 vq_err(vq, "Invalid length in indirect descriptor: "
2169                        "len 0x%llx not multiple of 0x%zx\n",
2170                        (unsigned long long)len,
2171                        sizeof desc);
2172                 return -EINVAL;
2173         }
2174
2175         ret = translate_desc(vq, vhost64_to_cpu(vq, indirect->addr), len, vq->indirect,
2176                              UIO_MAXIOV, VHOST_ACCESS_RO);
2177         if (unlikely(ret < 0)) {
2178                 if (ret != -EAGAIN)
2179                         vq_err(vq, "Translation failure %d in indirect.\n", ret);
2180                 return ret;
2181         }
2182         iov_iter_init(&from, ITER_SOURCE, vq->indirect, ret, len);
2183         count = len / sizeof desc;
2184         /* Buffers are chained via a 16 bit next field, so
2185          * we can have at most 2^16 of these. */
2186         if (unlikely(count > USHRT_MAX + 1)) {
2187                 vq_err(vq, "Indirect buffer length too big: %d\n",
2188                        indirect->len);
2189                 return -E2BIG;
2190         }
2191
2192         do {
2193                 unsigned iov_count = *in_num + *out_num;
2194                 if (unlikely(++found > count)) {
2195                         vq_err(vq, "Loop detected: last one at %u "
2196                                "indirect size %u\n",
2197                                i, count);
2198                         return -EINVAL;
2199                 }
2200                 if (unlikely(!copy_from_iter_full(&desc, sizeof(desc), &from))) {
2201                         vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n",
2202                                i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
2203                         return -EINVAL;
2204                 }
2205                 if (unlikely(desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT))) {
2206                         vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n",
2207                                i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
2208                         return -EINVAL;
2209                 }
2210
2211                 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
2212                         access = VHOST_ACCESS_WO;
2213                 else
2214                         access = VHOST_ACCESS_RO;
2215
2216                 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
2217                                      vhost32_to_cpu(vq, desc.len), iov + iov_count,
2218                                      iov_size - iov_count, access);
2219                 if (unlikely(ret < 0)) {
2220                         if (ret != -EAGAIN)
2221                                 vq_err(vq, "Translation failure %d indirect idx %d\n",
2222                                         ret, i);
2223                         return ret;
2224                 }
2225                 /* If this is an input descriptor, increment that count. */
2226                 if (access == VHOST_ACCESS_WO) {
2227                         *in_num += ret;
2228                         if (unlikely(log && ret)) {
2229                                 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
2230                                 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
2231                                 ++*log_num;
2232                         }
2233                 } else {
2234                         /* If it's an output descriptor, they're all supposed
2235                          * to come before any input descriptors. */
2236                         if (unlikely(*in_num)) {
2237                                 vq_err(vq, "Indirect descriptor "
2238                                        "has out after in: idx %d\n", i);
2239                                 return -EINVAL;
2240                         }
2241                         *out_num += ret;
2242                 }
2243         } while ((i = next_desc(vq, &desc)) != -1);
2244         return 0;
2245 }
2246
2247 /* This looks in the virtqueue and for the first available buffer, and converts
2248  * it to an iovec for convenient access.  Since descriptors consist of some
2249  * number of output then some number of input descriptors, it's actually two
2250  * iovecs, but we pack them into one and note how many of each there were.
2251  *
2252  * This function returns the descriptor number found, or vq->num (which is
2253  * never a valid descriptor number) if none was found.  A negative code is
2254  * returned on error. */
2255 int vhost_get_vq_desc(struct vhost_virtqueue *vq,
2256                       struct iovec iov[], unsigned int iov_size,
2257                       unsigned int *out_num, unsigned int *in_num,
2258                       struct vhost_log *log, unsigned int *log_num)
2259 {
2260         struct vring_desc desc;
2261         unsigned int i, head, found = 0;
2262         u16 last_avail_idx;
2263         __virtio16 avail_idx;
2264         __virtio16 ring_head;
2265         int ret, access;
2266
2267         /* Check it isn't doing very strange things with descriptor numbers. */
2268         last_avail_idx = vq->last_avail_idx;
2269
2270         if (vq->avail_idx == vq->last_avail_idx) {
2271                 if (unlikely(vhost_get_avail_idx(vq, &avail_idx))) {
2272                         vq_err(vq, "Failed to access avail idx at %p\n",
2273                                 &vq->avail->idx);
2274                         return -EFAULT;
2275                 }
2276                 vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
2277
2278                 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
2279                         vq_err(vq, "Guest moved used index from %u to %u",
2280                                 last_avail_idx, vq->avail_idx);
2281                         return -EFAULT;
2282                 }
2283
2284                 /* If there's nothing new since last we looked, return
2285                  * invalid.
2286                  */
2287                 if (vq->avail_idx == last_avail_idx)
2288                         return vq->num;
2289
2290                 /* Only get avail ring entries after they have been
2291                  * exposed by guest.
2292                  */
2293                 smp_rmb();
2294         }
2295
2296         /* Grab the next descriptor number they're advertising, and increment
2297          * the index we've seen. */
2298         if (unlikely(vhost_get_avail_head(vq, &ring_head, last_avail_idx))) {
2299                 vq_err(vq, "Failed to read head: idx %d address %p\n",
2300                        last_avail_idx,
2301                        &vq->avail->ring[last_avail_idx % vq->num]);
2302                 return -EFAULT;
2303         }
2304
2305         head = vhost16_to_cpu(vq, ring_head);
2306
2307         /* If their number is silly, that's an error. */
2308         if (unlikely(head >= vq->num)) {
2309                 vq_err(vq, "Guest says index %u > %u is available",
2310                        head, vq->num);
2311                 return -EINVAL;
2312         }
2313
2314         /* When we start there are none of either input nor output. */
2315         *out_num = *in_num = 0;
2316         if (unlikely(log))
2317                 *log_num = 0;
2318
2319         i = head;
2320         do {
2321                 unsigned iov_count = *in_num + *out_num;
2322                 if (unlikely(i >= vq->num)) {
2323                         vq_err(vq, "Desc index is %u > %u, head = %u",
2324                                i, vq->num, head);
2325                         return -EINVAL;
2326                 }
2327                 if (unlikely(++found > vq->num)) {
2328                         vq_err(vq, "Loop detected: last one at %u "
2329                                "vq size %u head %u\n",
2330                                i, vq->num, head);
2331                         return -EINVAL;
2332                 }
2333                 ret = vhost_get_desc(vq, &desc, i);
2334                 if (unlikely(ret)) {
2335                         vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
2336                                i, vq->desc + i);
2337                         return -EFAULT;
2338                 }
2339                 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT)) {
2340                         ret = get_indirect(vq, iov, iov_size,
2341                                            out_num, in_num,
2342                                            log, log_num, &desc);
2343                         if (unlikely(ret < 0)) {
2344                                 if (ret != -EAGAIN)
2345                                         vq_err(vq, "Failure detected "
2346                                                 "in indirect descriptor at idx %d\n", i);
2347                                 return ret;
2348                         }
2349                         continue;
2350                 }
2351
2352                 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
2353                         access = VHOST_ACCESS_WO;
2354                 else
2355                         access = VHOST_ACCESS_RO;
2356                 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
2357                                      vhost32_to_cpu(vq, desc.len), iov + iov_count,
2358                                      iov_size - iov_count, access);
2359                 if (unlikely(ret < 0)) {
2360                         if (ret != -EAGAIN)
2361                                 vq_err(vq, "Translation failure %d descriptor idx %d\n",
2362                                         ret, i);
2363                         return ret;
2364                 }
2365                 if (access == VHOST_ACCESS_WO) {
2366                         /* If this is an input descriptor,
2367                          * increment that count. */
2368                         *in_num += ret;
2369                         if (unlikely(log && ret)) {
2370                                 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
2371                                 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
2372                                 ++*log_num;
2373                         }
2374                 } else {
2375                         /* If it's an output descriptor, they're all supposed
2376                          * to come before any input descriptors. */
2377                         if (unlikely(*in_num)) {
2378                                 vq_err(vq, "Descriptor has out after in: "
2379                                        "idx %d\n", i);
2380                                 return -EINVAL;
2381                         }
2382                         *out_num += ret;
2383                 }
2384         } while ((i = next_desc(vq, &desc)) != -1);
2385
2386         /* On success, increment avail index. */
2387         vq->last_avail_idx++;
2388
2389         /* Assume notifications from guest are disabled at this point,
2390          * if they aren't we would need to update avail_event index. */
2391         BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
2392         return head;
2393 }
2394 EXPORT_SYMBOL_GPL(vhost_get_vq_desc);
2395
2396 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
2397 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
2398 {
2399         vq->last_avail_idx -= n;
2400 }
2401 EXPORT_SYMBOL_GPL(vhost_discard_vq_desc);
2402
2403 /* After we've used one of their buffers, we tell them about it.  We'll then
2404  * want to notify the guest, using eventfd. */
2405 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
2406 {
2407         struct vring_used_elem heads = {
2408                 cpu_to_vhost32(vq, head),
2409                 cpu_to_vhost32(vq, len)
2410         };
2411
2412         return vhost_add_used_n(vq, &heads, 1);
2413 }
2414 EXPORT_SYMBOL_GPL(vhost_add_used);
2415
2416 static int __vhost_add_used_n(struct vhost_virtqueue *vq,
2417                             struct vring_used_elem *heads,
2418                             unsigned count)
2419 {
2420         vring_used_elem_t __user *used;
2421         u16 old, new;
2422         int start;
2423
2424         start = vq->last_used_idx & (vq->num - 1);
2425         used = vq->used->ring + start;
2426         if (vhost_put_used(vq, heads, start, count)) {
2427                 vq_err(vq, "Failed to write used");
2428                 return -EFAULT;
2429         }
2430         if (unlikely(vq->log_used)) {
2431                 /* Make sure data is seen before log. */
2432                 smp_wmb();
2433                 /* Log used ring entry write. */
2434                 log_used(vq, ((void __user *)used - (void __user *)vq->used),
2435                          count * sizeof *used);
2436         }
2437         old = vq->last_used_idx;
2438         new = (vq->last_used_idx += count);
2439         /* If the driver never bothers to signal in a very long while,
2440          * used index might wrap around. If that happens, invalidate
2441          * signalled_used index we stored. TODO: make sure driver
2442          * signals at least once in 2^16 and remove this. */
2443         if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old)))
2444                 vq->signalled_used_valid = false;
2445         return 0;
2446 }
2447
2448 /* After we've used one of their buffers, we tell them about it.  We'll then
2449  * want to notify the guest, using eventfd. */
2450 int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
2451                      unsigned count)
2452 {
2453         int start, n, r;
2454
2455         start = vq->last_used_idx & (vq->num - 1);
2456         n = vq->num - start;
2457         if (n < count) {
2458                 r = __vhost_add_used_n(vq, heads, n);
2459                 if (r < 0)
2460                         return r;
2461                 heads += n;
2462                 count -= n;
2463         }
2464         r = __vhost_add_used_n(vq, heads, count);
2465
2466         /* Make sure buffer is written before we update index. */
2467         smp_wmb();
2468         if (vhost_put_used_idx(vq)) {
2469                 vq_err(vq, "Failed to increment used idx");
2470                 return -EFAULT;
2471         }
2472         if (unlikely(vq->log_used)) {
2473                 /* Make sure used idx is seen before log. */
2474                 smp_wmb();
2475                 /* Log used index update. */
2476                 log_used(vq, offsetof(struct vring_used, idx),
2477                          sizeof vq->used->idx);
2478                 if (vq->log_ctx)
2479                         eventfd_signal(vq->log_ctx, 1);
2480         }
2481         return r;
2482 }
2483 EXPORT_SYMBOL_GPL(vhost_add_used_n);
2484
2485 static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2486 {
2487         __u16 old, new;
2488         __virtio16 event;
2489         bool v;
2490         /* Flush out used index updates. This is paired
2491          * with the barrier that the Guest executes when enabling
2492          * interrupts. */
2493         smp_mb();
2494
2495         if (vhost_has_feature(vq, VIRTIO_F_NOTIFY_ON_EMPTY) &&
2496             unlikely(vq->avail_idx == vq->last_avail_idx))
2497                 return true;
2498
2499         if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2500                 __virtio16 flags;
2501                 if (vhost_get_avail_flags(vq, &flags)) {
2502                         vq_err(vq, "Failed to get flags");
2503                         return true;
2504                 }
2505                 return !(flags & cpu_to_vhost16(vq, VRING_AVAIL_F_NO_INTERRUPT));
2506         }
2507         old = vq->signalled_used;
2508         v = vq->signalled_used_valid;
2509         new = vq->signalled_used = vq->last_used_idx;
2510         vq->signalled_used_valid = true;
2511
2512         if (unlikely(!v))
2513                 return true;
2514
2515         if (vhost_get_used_event(vq, &event)) {
2516                 vq_err(vq, "Failed to get used event idx");
2517                 return true;
2518         }
2519         return vring_need_event(vhost16_to_cpu(vq, event), new, old);
2520 }
2521
2522 /* This actually signals the guest, using eventfd. */
2523 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2524 {
2525         /* Signal the Guest tell them we used something up. */
2526         if (vq->call_ctx.ctx && vhost_notify(dev, vq))
2527                 eventfd_signal(vq->call_ctx.ctx, 1);
2528 }
2529 EXPORT_SYMBOL_GPL(vhost_signal);
2530
2531 /* And here's the combo meal deal.  Supersize me! */
2532 void vhost_add_used_and_signal(struct vhost_dev *dev,
2533                                struct vhost_virtqueue *vq,
2534                                unsigned int head, int len)
2535 {
2536         vhost_add_used(vq, head, len);
2537         vhost_signal(dev, vq);
2538 }
2539 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal);
2540
2541 /* multi-buffer version of vhost_add_used_and_signal */
2542 void vhost_add_used_and_signal_n(struct vhost_dev *dev,
2543                                  struct vhost_virtqueue *vq,
2544                                  struct vring_used_elem *heads, unsigned count)
2545 {
2546         vhost_add_used_n(vq, heads, count);
2547         vhost_signal(dev, vq);
2548 }
2549 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n);
2550
2551 /* return true if we're sure that avaiable ring is empty */
2552 bool vhost_vq_avail_empty(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2553 {
2554         __virtio16 avail_idx;
2555         int r;
2556
2557         if (vq->avail_idx != vq->last_avail_idx)
2558                 return false;
2559
2560         r = vhost_get_avail_idx(vq, &avail_idx);
2561         if (unlikely(r))
2562                 return false;
2563         vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
2564
2565         return vq->avail_idx == vq->last_avail_idx;
2566 }
2567 EXPORT_SYMBOL_GPL(vhost_vq_avail_empty);
2568
2569 /* OK, now we need to know about added descriptors. */
2570 bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2571 {
2572         __virtio16 avail_idx;
2573         int r;
2574
2575         if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
2576                 return false;
2577         vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
2578         if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2579                 r = vhost_update_used_flags(vq);
2580                 if (r) {
2581                         vq_err(vq, "Failed to enable notification at %p: %d\n",
2582                                &vq->used->flags, r);
2583                         return false;
2584                 }
2585         } else {
2586                 r = vhost_update_avail_event(vq);
2587                 if (r) {
2588                         vq_err(vq, "Failed to update avail event index at %p: %d\n",
2589                                vhost_avail_event(vq), r);
2590                         return false;
2591                 }
2592         }
2593         /* They could have slipped one in as we were doing that: make
2594          * sure it's written, then check again. */
2595         smp_mb();
2596         r = vhost_get_avail_idx(vq, &avail_idx);
2597         if (r) {
2598                 vq_err(vq, "Failed to check avail idx at %p: %d\n",
2599                        &vq->avail->idx, r);
2600                 return false;
2601         }
2602         vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
2603
2604         return vq->avail_idx != vq->last_avail_idx;
2605 }
2606 EXPORT_SYMBOL_GPL(vhost_enable_notify);
2607
2608 /* We don't need to be notified again. */
2609 void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2610 {
2611         int r;
2612
2613         if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
2614                 return;
2615         vq->used_flags |= VRING_USED_F_NO_NOTIFY;
2616         if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2617                 r = vhost_update_used_flags(vq);
2618                 if (r)
2619                         vq_err(vq, "Failed to disable notification at %p: %d\n",
2620                                &vq->used->flags, r);
2621         }
2622 }
2623 EXPORT_SYMBOL_GPL(vhost_disable_notify);
2624
2625 /* Create a new message. */
2626 struct vhost_msg_node *vhost_new_msg(struct vhost_virtqueue *vq, int type)
2627 {
2628         /* Make sure all padding within the structure is initialized. */
2629         struct vhost_msg_node *node = kzalloc(sizeof(*node), GFP_KERNEL);
2630         if (!node)
2631                 return NULL;
2632
2633         node->vq = vq;
2634         node->msg.type = type;
2635         return node;
2636 }
2637 EXPORT_SYMBOL_GPL(vhost_new_msg);
2638
2639 void vhost_enqueue_msg(struct vhost_dev *dev, struct list_head *head,
2640                        struct vhost_msg_node *node)
2641 {
2642         spin_lock(&dev->iotlb_lock);
2643         list_add_tail(&node->node, head);
2644         spin_unlock(&dev->iotlb_lock);
2645
2646         wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
2647 }
2648 EXPORT_SYMBOL_GPL(vhost_enqueue_msg);
2649
2650 struct vhost_msg_node *vhost_dequeue_msg(struct vhost_dev *dev,
2651                                          struct list_head *head)
2652 {
2653         struct vhost_msg_node *node = NULL;
2654
2655         spin_lock(&dev->iotlb_lock);
2656         if (!list_empty(head)) {
2657                 node = list_first_entry(head, struct vhost_msg_node,
2658                                         node);
2659                 list_del(&node->node);
2660         }
2661         spin_unlock(&dev->iotlb_lock);
2662
2663         return node;
2664 }
2665 EXPORT_SYMBOL_GPL(vhost_dequeue_msg);
2666
2667 void vhost_set_backend_features(struct vhost_dev *dev, u64 features)
2668 {
2669         struct vhost_virtqueue *vq;
2670         int i;
2671
2672         mutex_lock(&dev->mutex);
2673         for (i = 0; i < dev->nvqs; ++i) {
2674                 vq = dev->vqs[i];
2675                 mutex_lock(&vq->mutex);
2676                 vq->acked_backend_features = features;
2677                 mutex_unlock(&vq->mutex);
2678         }
2679         mutex_unlock(&dev->mutex);
2680 }
2681 EXPORT_SYMBOL_GPL(vhost_set_backend_features);
2682
2683 static int __init vhost_init(void)
2684 {
2685         return 0;
2686 }
2687
2688 static void __exit vhost_exit(void)
2689 {
2690 }
2691
2692 module_init(vhost_init);
2693 module_exit(vhost_exit);
2694
2695 MODULE_VERSION("0.0.1");
2696 MODULE_LICENSE("GPL v2");
2697 MODULE_AUTHOR("Michael S. Tsirkin");
2698 MODULE_DESCRIPTION("Host kernel accelerator for virtio");