drivers/vhost/vhost.c

   1 /* Copyright (C) 2009 Red Hat, Inc.
   2  * Copyright (C) 2006 Rusty Russell IBM Corporation
   3  *
   4  * Author: Michael S. Tsirkin <mst@redhat.com>
   5  *
   6  * Inspiration, some code, and most witty comments come from
   7  * Documentation/virtual/lguest/lguest.c, by Rusty Russell
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2.
  10  *
  11  * Generic code for virtio server in host kernel.
  12  */
  13
  14 #include <linux/eventfd.h>
  15 #include <linux/vhost.h>
  16 #include <linux/uio.h>
  17 #include <linux/mm.h>
  18 #include <linux/mmu_context.h>
  19 #include <linux/miscdevice.h>
  20 #include <linux/mutex.h>
  21 #include <linux/poll.h>
  22 #include <linux/file.h>
  23 #include <linux/highmem.h>
  24 #include <linux/slab.h>
  25 #include <linux/vmalloc.h>
  26 #include <linux/kthread.h>
  27 #include <linux/cgroup.h>
  28 #include <linux/module.h>
  29 #include <linux/sort.h>
  30 #include <linux/sched/mm.h>
  31 #include <linux/sched/signal.h>
  32 #include <linux/interval_tree_generic.h>
  33 #include <linux/nospec.h>
  34
  35 #include "vhost.h"
  36
  37 static ushort max_mem_regions = 64;
  38 module_param(max_mem_regions, ushort, 0444);
  39 MODULE_PARM_DESC(max_mem_regions,
  40         "Maximum number of memory regions in memory map. (default: 64)");
  41 static int max_iotlb_entries = 2048;
  42 module_param(max_iotlb_entries, int, 0444);
  43 MODULE_PARM_DESC(max_iotlb_entries,
  44         "Maximum number of iotlb entries. (default: 2048)");
  45
  46 enum {
  47         VHOST_MEMORY_F_LOG = 0x1,
  48 };
  49
  50 #define vhost_used_event(vq) ((__virtio16 __user *)&vq->avail->ring[vq->num])
  51 #define vhost_avail_event(vq) ((__virtio16 __user *)&vq->used->ring[vq->num])
  52
  53 INTERVAL_TREE_DEFINE(struct vhost_umem_node,
  54                      rb, __u64, __subtree_last,
  55                      START, LAST, static inline, vhost_umem_interval_tree);
  56
  57 #ifdef CONFIG_VHOST_CROSS_ENDIAN_LEGACY
  58 static void vhost_disable_cross_endian(struct vhost_virtqueue *vq)
  59 {
  60         vq->user_be = !virtio_legacy_is_little_endian();
  61 }
  62
  63 static void vhost_enable_cross_endian_big(struct vhost_virtqueue *vq)
  64 {
  65         vq->user_be = true;
  66 }
  67
  68 static void vhost_enable_cross_endian_little(struct vhost_virtqueue *vq)
  69 {
  70         vq->user_be = false;
  71 }
  72
  73 static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp)
  74 {
  75         struct vhost_vring_state s;
  76
  77         if (vq->private_data)
  78                 return -EBUSY;
  79
  80         if (copy_from_user(&s, argp, sizeof(s)))
  81                 return -EFAULT;
  82
  83         if (s.num != VHOST_VRING_LITTLE_ENDIAN &&
  84             s.num != VHOST_VRING_BIG_ENDIAN)
  85                 return -EINVAL;
  86
  87         if (s.num == VHOST_VRING_BIG_ENDIAN)
  88                 vhost_enable_cross_endian_big(vq);
  89         else
  90                 vhost_enable_cross_endian_little(vq);
  91
  92         return 0;
  93 }
  94
  95 static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx,
  96                                    int __user *argp)
  97 {
  98         struct vhost_vring_state s = {
  99                 .index = idx,
 100                 .num = vq->user_be
 101         };
 102
 103         if (copy_to_user(argp, &s, sizeof(s)))
 104                 return -EFAULT;
 105
 106         return 0;
 107 }
 108
 109 static void vhost_init_is_le(struct vhost_virtqueue *vq)
 110 {
 111         /* Note for legacy virtio: user_be is initialized at reset time
 112          * according to the host endianness. If userspace does not set an
 113          * explicit endianness, the default behavior is native endian, as
 114          * expected by legacy virtio.
 115          */
 116         vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1) || !vq->user_be;
 117 }
 118 #else
 119 static void vhost_disable_cross_endian(struct vhost_virtqueue *vq)
 120 {
 121 }
 122
 123 static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp)
 124 {
 125         return -ENOIOCTLCMD;
 126 }
 127
 128 static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx,
 129                                    int __user *argp)
 130 {
 131         return -ENOIOCTLCMD;
 132 }
 133
 134 static void vhost_init_is_le(struct vhost_virtqueue *vq)
 135 {
 136         vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1)
 137                 || virtio_legacy_is_little_endian();
 138 }
 139 #endif /* CONFIG_VHOST_CROSS_ENDIAN_LEGACY */
 140
 141 static void vhost_reset_is_le(struct vhost_virtqueue *vq)
 142 {
 143         vhost_init_is_le(vq);
 144 }
 145
 146 struct vhost_flush_struct {
 147         struct vhost_work work;
 148         struct completion wait_event;
 149 };
 150
 151 static void vhost_flush_work(struct vhost_work *work)
 152 {
 153         struct vhost_flush_struct *s;
 154
 155         s = container_of(work, struct vhost_flush_struct, work);
 156         complete(&s->wait_event);
 157 }
 158
 159 static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh,
 160                             poll_table *pt)
 161 {
 162         struct vhost_poll *poll;
 163
 164         poll = container_of(pt, struct vhost_poll, table);
 165         poll->wqh = wqh;
 166         add_wait_queue(wqh, &poll->wait);
 167 }
 168
 169 static int vhost_poll_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync,
 170                              void *key)
 171 {
 172         struct vhost_poll *poll = container_of(wait, struct vhost_poll, wait);
 173
 174         if (!(key_to_poll(key) & poll->mask))
 175                 return 0;
 176
 177         vhost_poll_queue(poll);
 178         return 0;
 179 }
 180
 181 void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn)
 182 {
 183         clear_bit(VHOST_WORK_QUEUED, &work->flags);
 184         work->fn = fn;
 185 }
 186 EXPORT_SYMBOL_GPL(vhost_work_init);
 187
 188 /* Init poll structure */
 189 void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
 190                      __poll_t mask, struct vhost_dev *dev)
 191 {
 192         init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup);
 193         init_poll_funcptr(&poll->table, vhost_poll_func);
 194         poll->mask = mask;
 195         poll->dev = dev;
 196         poll->wqh = NULL;
 197
 198         vhost_work_init(&poll->work, fn);
 199 }
 200 EXPORT_SYMBOL_GPL(vhost_poll_init);
 201
 202 /* Start polling a file. We add ourselves to file's wait queue. The caller must
 203  * keep a reference to a file until after vhost_poll_stop is called. */
 204 int vhost_poll_start(struct vhost_poll *poll, struct file *file)
 205 {
 206         __poll_t mask;
 207         int ret = 0;
 208
 209         if (poll->wqh)
 210                 return 0;
 211
 212         mask = vfs_poll(file, &poll->table);
 213         if (mask)
 214                 vhost_poll_wakeup(&poll->wait, 0, 0, poll_to_key(mask));
 215         if (mask & EPOLLERR) {
 216                 vhost_poll_stop(poll);
 217                 ret = -EINVAL;
 218         }
 219
 220         return ret;
 221 }
 222 EXPORT_SYMBOL_GPL(vhost_poll_start);
 223
 224 /* Stop polling a file. After this function returns, it becomes safe to drop the
 225  * file reference. You must also flush afterwards. */
 226 void vhost_poll_stop(struct vhost_poll *poll)
 227 {
 228         if (poll->wqh) {
 229                 remove_wait_queue(poll->wqh, &poll->wait);
 230                 poll->wqh = NULL;
 231         }
 232 }
 233 EXPORT_SYMBOL_GPL(vhost_poll_stop);
 234
 235 void vhost_work_flush(struct vhost_dev *dev, struct vhost_work *work)
 236 {
 237         struct vhost_flush_struct flush;
 238
 239         if (dev->worker) {
 240                 init_completion(&flush.wait_event);
 241                 vhost_work_init(&flush.work, vhost_flush_work);
 242
 243                 vhost_work_queue(dev, &flush.work);
 244                 wait_for_completion(&flush.wait_event);
 245         }
 246 }
 247 EXPORT_SYMBOL_GPL(vhost_work_flush);
 248
 249 /* Flush any work that has been scheduled. When calling this, don't hold any
 250  * locks that are also used by the callback. */
 251 void vhost_poll_flush(struct vhost_poll *poll)
 252 {
 253         vhost_work_flush(poll->dev, &poll->work);
 254 }
 255 EXPORT_SYMBOL_GPL(vhost_poll_flush);
 256
 257 void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work)
 258 {
 259         if (!dev->worker)
 260                 return;
 261
 262         if (!test_and_set_bit(VHOST_WORK_QUEUED, &work->flags)) {
 263                 /* We can only add the work to the list after we're
 264                  * sure it was not in the list.
 265                  * test_and_set_bit() implies a memory barrier.
 266                  */
 267                 llist_add(&work->node, &dev->work_list);
 268                 wake_up_process(dev->worker);
 269         }
 270 }
 271 EXPORT_SYMBOL_GPL(vhost_work_queue);
 272
 273 /* A lockless hint for busy polling code to exit the loop */
 274 bool vhost_has_work(struct vhost_dev *dev)
 275 {
 276         return !llist_empty(&dev->work_list);
 277 }
 278 EXPORT_SYMBOL_GPL(vhost_has_work);
 279
 280 void vhost_poll_queue(struct vhost_poll *poll)
 281 {
 282         vhost_work_queue(poll->dev, &poll->work);
 283 }
 284 EXPORT_SYMBOL_GPL(vhost_poll_queue);
 285
 286 static void __vhost_vq_meta_reset(struct vhost_virtqueue *vq)
 287 {
 288         int j;
 289
 290         for (j = 0; j < VHOST_NUM_ADDRS; j++)
 291                 vq->meta_iotlb[j] = NULL;
 292 }
 293
 294 static void vhost_vq_meta_reset(struct vhost_dev *d)
 295 {
 296         int i;
 297
 298         for (i = 0; i < d->nvqs; ++i)
 299                 __vhost_vq_meta_reset(d->vqs[i]);
 300 }
 301
 302 static void vhost_vq_reset(struct vhost_dev *dev,
 303                            struct vhost_virtqueue *vq)
 304 {
 305         vq->num = 1;
 306         vq->desc = NULL;
 307         vq->avail = NULL;
 308         vq->used = NULL;
 309         vq->last_avail_idx = 0;
 310         vq->avail_idx = 0;
 311         vq->last_used_idx = 0;
 312         vq->signalled_used = 0;
 313         vq->signalled_used_valid = false;
 314         vq->used_flags = 0;
 315         vq->log_used = false;
 316         vq->log_addr = -1ull;
 317         vq->private_data = NULL;
 318         vq->acked_features = 0;
 319         vq->acked_backend_features = 0;
 320         vq->log_base = NULL;
 321         vq->error_ctx = NULL;
 322         vq->kick = NULL;
 323         vq->call_ctx = NULL;
 324         vq->log_ctx = NULL;
 325         vhost_reset_is_le(vq);
 326         vhost_disable_cross_endian(vq);
 327         vq->busyloop_timeout = 0;
 328         vq->umem = NULL;
 329         vq->iotlb = NULL;
 330         __vhost_vq_meta_reset(vq);
 331 }
 332
 333 static int vhost_worker(void *data)
 334 {
 335         struct vhost_dev *dev = data;
 336         struct vhost_work *work, *work_next;
 337         struct llist_node *node;
 338         mm_segment_t oldfs = get_fs();
 339
 340         set_fs(USER_DS);
 341         use_mm(dev->mm);
 342
 343         for (;;) {
 344                 /* mb paired w/ kthread_stop */
 345                 set_current_state(TASK_INTERRUPTIBLE);
 346
 347                 if (kthread_should_stop()) {
 348                         __set_current_state(TASK_RUNNING);
 349                         break;
 350                 }
 351
 352                 node = llist_del_all(&dev->work_list);
 353                 if (!node)
 354                         schedule();
 355
 356                 node = llist_reverse_order(node);
 357                 /* make sure flag is seen after deletion */
 358                 smp_wmb();
 359                 llist_for_each_entry_safe(work, work_next, node, node) {
 360                         clear_bit(VHOST_WORK_QUEUED, &work->flags);
 361                         __set_current_state(TASK_RUNNING);
 362                         work->fn(work);
 363                         if (need_resched())
 364                                 schedule();
 365                 }
 366         }
 367         unuse_mm(dev->mm);
 368         set_fs(oldfs);
 369         return 0;
 370 }
 371
 372 static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq)
 373 {
 374         kfree(vq->indirect);
 375         vq->indirect = NULL;
 376         kfree(vq->log);
 377         vq->log = NULL;
 378         kfree(vq->heads);
 379         vq->heads = NULL;
 380 }
 381
 382 /* Helper to allocate iovec buffers for all vqs. */
 383 static long vhost_dev_alloc_iovecs(struct vhost_dev *dev)
 384 {
 385         struct vhost_virtqueue *vq;
 386         int i;
 387
 388         for (i = 0; i < dev->nvqs; ++i) {
 389                 vq = dev->vqs[i];
 390                 vq->indirect = kmalloc_array(UIO_MAXIOV,
 391                                              sizeof(*vq->indirect),
 392                                              GFP_KERNEL);
 393                 vq->log = kmalloc_array(dev->iov_limit, sizeof(*vq->log),
 394                                         GFP_KERNEL);
 395                 vq->heads = kmalloc_array(dev->iov_limit, sizeof(*vq->heads),
 396                                           GFP_KERNEL);
 397                 if (!vq->indirect || !vq->log || !vq->heads)
 398                         goto err_nomem;
 399         }
 400         return 0;
 401
 402 err_nomem:
 403         for (; i >= 0; --i)
 404                 vhost_vq_free_iovecs(dev->vqs[i]);
 405         return -ENOMEM;
 406 }
 407
 408 static void vhost_dev_free_iovecs(struct vhost_dev *dev)
 409 {
 410         int i;
 411
 412         for (i = 0; i < dev->nvqs; ++i)
 413                 vhost_vq_free_iovecs(dev->vqs[i]);
 414 }
 415
 416 void vhost_dev_init(struct vhost_dev *dev,
 417                     struct vhost_virtqueue **vqs, int nvqs, int iov_limit)
 418 {
 419         struct vhost_virtqueue *vq;
 420         int i;
 421
 422         dev->vqs = vqs;
 423         dev->nvqs = nvqs;
 424         mutex_init(&dev->mutex);
 425         dev->log_ctx = NULL;
 426         dev->umem = NULL;
 427         dev->iotlb = NULL;
 428         dev->mm = NULL;
 429         dev->worker = NULL;
 430         dev->iov_limit = iov_limit;
 431         init_llist_head(&dev->work_list);
 432         init_waitqueue_head(&dev->wait);
 433         INIT_LIST_HEAD(&dev->read_list);
 434         INIT_LIST_HEAD(&dev->pending_list);
 435         spin_lock_init(&dev->iotlb_lock);
 436
 437
 438         for (i = 0; i < dev->nvqs; ++i) {
 439                 vq = dev->vqs[i];
 440                 vq->log = NULL;
 441                 vq->indirect = NULL;
 442                 vq->heads = NULL;
 443                 vq->dev = dev;
 444                 mutex_init(&vq->mutex);
 445                 vhost_vq_reset(dev, vq);
 446                 if (vq->handle_kick)
 447                         vhost_poll_init(&vq->poll, vq->handle_kick,
 448                                         EPOLLIN, dev);
 449         }
 450 }
 451 EXPORT_SYMBOL_GPL(vhost_dev_init);
 452
 453 /* Caller should have device mutex */
 454 long vhost_dev_check_owner(struct vhost_dev *dev)
 455 {
 456         /* Are you the owner? If not, I don't think you mean to do that */
 457         return dev->mm == current->mm ? 0 : -EPERM;
 458 }
 459 EXPORT_SYMBOL_GPL(vhost_dev_check_owner);
 460
 461 struct vhost_attach_cgroups_struct {
 462         struct vhost_work work;
 463         struct task_struct *owner;
 464         int ret;
 465 };
 466
 467 static void vhost_attach_cgroups_work(struct vhost_work *work)
 468 {
 469         struct vhost_attach_cgroups_struct *s;
 470
 471         s = container_of(work, struct vhost_attach_cgroups_struct, work);
 472         s->ret = cgroup_attach_task_all(s->owner, current);
 473 }
 474
 475 static int vhost_attach_cgroups(struct vhost_dev *dev)
 476 {
 477         struct vhost_attach_cgroups_struct attach;
 478
 479         attach.owner = current;
 480         vhost_work_init(&attach.work, vhost_attach_cgroups_work);
 481         vhost_work_queue(dev, &attach.work);
 482         vhost_work_flush(dev, &attach.work);
 483         return attach.ret;
 484 }
 485
 486 /* Caller should have device mutex */
 487 bool vhost_dev_has_owner(struct vhost_dev *dev)
 488 {
 489         return dev->mm;
 490 }
 491 EXPORT_SYMBOL_GPL(vhost_dev_has_owner);
 492
 493 /* Caller should have device mutex */
 494 long vhost_dev_set_owner(struct vhost_dev *dev)
 495 {
 496         struct task_struct *worker;
 497         int err;
 498
 499         /* Is there an owner already? */
 500         if (vhost_dev_has_owner(dev)) {
 501                 err = -EBUSY;
 502                 goto err_mm;
 503         }
 504
 505         /* No owner, become one */
 506         dev->mm = get_task_mm(current);
 507         worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid);
 508         if (IS_ERR(worker)) {
 509                 err = PTR_ERR(worker);
 510                 goto err_worker;
 511         }
 512
 513         dev->worker = worker;
 514         wake_up_process(worker);        /* avoid contributing to loadavg */
 515
 516         err = vhost_attach_cgroups(dev);
 517         if (err)
 518                 goto err_cgroup;
 519
 520         err = vhost_dev_alloc_iovecs(dev);
 521         if (err)
 522                 goto err_cgroup;
 523
 524         return 0;
 525 err_cgroup:
 526         kthread_stop(worker);
 527         dev->worker = NULL;
 528 err_worker:
 529         if (dev->mm)
 530                 mmput(dev->mm);
 531         dev->mm = NULL;
 532 err_mm:
 533         return err;
 534 }
 535 EXPORT_SYMBOL_GPL(vhost_dev_set_owner);
 536
 537 struct vhost_umem *vhost_dev_reset_owner_prepare(void)
 538 {
 539         return kvzalloc(sizeof(struct vhost_umem), GFP_KERNEL);
 540 }
 541 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner_prepare);
 542
 543 /* Caller should have device mutex */
 544 void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_umem *umem)
 545 {
 546         int i;
 547
 548         vhost_dev_cleanup(dev);
 549
 550         /* Restore memory to default empty mapping. */
 551         INIT_LIST_HEAD(&umem->umem_list);
 552         dev->umem = umem;
 553         /* We don't need VQ locks below since vhost_dev_cleanup makes sure
 554          * VQs aren't running.
 555          */
 556         for (i = 0; i < dev->nvqs; ++i)
 557                 dev->vqs[i]->umem = umem;
 558 }
 559 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner);
 560
 561 void vhost_dev_stop(struct vhost_dev *dev)
 562 {
 563         int i;
 564
 565         for (i = 0; i < dev->nvqs; ++i) {
 566                 if (dev->vqs[i]->kick && dev->vqs[i]->handle_kick) {
 567                         vhost_poll_stop(&dev->vqs[i]->poll);
 568                         vhost_poll_flush(&dev->vqs[i]->poll);
 569                 }
 570         }
 571 }
 572 EXPORT_SYMBOL_GPL(vhost_dev_stop);
 573
 574 static void vhost_umem_free(struct vhost_umem *umem,
 575                             struct vhost_umem_node *node)
 576 {
 577         vhost_umem_interval_tree_remove(node, &umem->umem_tree);
 578         list_del(&node->link);
 579         kfree(node);
 580         umem->numem--;
 581 }
 582
 583 static void vhost_umem_clean(struct vhost_umem *umem)
 584 {
 585         struct vhost_umem_node *node, *tmp;
 586
 587         if (!umem)
 588                 return;
 589
 590         list_for_each_entry_safe(node, tmp, &umem->umem_list, link)
 591                 vhost_umem_free(umem, node);
 592
 593         kvfree(umem);
 594 }
 595
 596 static void vhost_clear_msg(struct vhost_dev *dev)
 597 {
 598         struct vhost_msg_node *node, *n;
 599
 600         spin_lock(&dev->iotlb_lock);
 601
 602         list_for_each_entry_safe(node, n, &dev->read_list, node) {
 603                 list_del(&node->node);
 604                 kfree(node);
 605         }
 606
 607         list_for_each_entry_safe(node, n, &dev->pending_list, node) {
 608                 list_del(&node->node);
 609                 kfree(node);
 610         }
 611
 612         spin_unlock(&dev->iotlb_lock);
 613 }
 614
 615 void vhost_dev_cleanup(struct vhost_dev *dev)
 616 {
 617         int i;
 618
 619         for (i = 0; i < dev->nvqs; ++i) {
 620                 if (dev->vqs[i]->error_ctx)
 621                         eventfd_ctx_put(dev->vqs[i]->error_ctx);
 622                 if (dev->vqs[i]->kick)
 623                         fput(dev->vqs[i]->kick);
 624                 if (dev->vqs[i]->call_ctx)
 625                         eventfd_ctx_put(dev->vqs[i]->call_ctx);
 626                 vhost_vq_reset(dev, dev->vqs[i]);
 627         }
 628         vhost_dev_free_iovecs(dev);
 629         if (dev->log_ctx)
 630                 eventfd_ctx_put(dev->log_ctx);
 631         dev->log_ctx = NULL;
 632         /* No one will access memory at this point */
 633         vhost_umem_clean(dev->umem);
 634         dev->umem = NULL;
 635         vhost_umem_clean(dev->iotlb);
 636         dev->iotlb = NULL;
 637         vhost_clear_msg(dev);
 638         wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
 639         WARN_ON(!llist_empty(&dev->work_list));
 640         if (dev->worker) {
 641                 kthread_stop(dev->worker);
 642                 dev->worker = NULL;
 643         }
 644         if (dev->mm)
 645                 mmput(dev->mm);
 646         dev->mm = NULL;
 647 }
 648 EXPORT_SYMBOL_GPL(vhost_dev_cleanup);
 649
 650 static bool log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
 651 {
 652         u64 a = addr / VHOST_PAGE_SIZE / 8;
 653
 654         /* Make sure 64 bit math will not overflow. */
 655         if (a > ULONG_MAX - (unsigned long)log_base ||
 656             a + (unsigned long)log_base > ULONG_MAX)
 657                 return false;
 658
 659         return access_ok(log_base + a,
 660                          (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8);
 661 }
 662
 663 static bool vhost_overflow(u64 uaddr, u64 size)
 664 {
 665         /* Make sure 64 bit math will not overflow. */
 666         return uaddr > ULONG_MAX || size > ULONG_MAX || uaddr > ULONG_MAX - size;
 667 }
 668
 669 /* Caller should have vq mutex and device mutex. */
 670 static bool vq_memory_access_ok(void __user *log_base, struct vhost_umem *umem,
 671                                 int log_all)
 672 {
 673         struct vhost_umem_node *node;
 674
 675         if (!umem)
 676                 return false;
 677
 678         list_for_each_entry(node, &umem->umem_list, link) {
 679                 unsigned long a = node->userspace_addr;
 680
 681                 if (vhost_overflow(node->userspace_addr, node->size))
 682                         return false;
 683
 684
 685                 if (!access_ok((void __user *)a,
 686                                     node->size))
 687                         return false;
 688                 else if (log_all && !log_access_ok(log_base,
 689                                                    node->start,
 690                                                    node->size))
 691                         return false;
 692         }
 693         return true;
 694 }
 695
 696 static inline void __user *vhost_vq_meta_fetch(struct vhost_virtqueue *vq,
 697                                                u64 addr, unsigned int size,
 698                                                int type)
 699 {
 700         const struct vhost_umem_node *node = vq->meta_iotlb[type];
 701
 702         if (!node)
 703                 return NULL;
 704
 705         return (void *)(uintptr_t)(node->userspace_addr + addr - node->start);
 706 }
 707
 708 /* Can we switch to this memory table? */
 709 /* Caller should have device mutex but not vq mutex */
 710 static bool memory_access_ok(struct vhost_dev *d, struct vhost_umem *umem,
 711                              int log_all)
 712 {
 713         int i;
 714
 715         for (i = 0; i < d->nvqs; ++i) {
 716                 bool ok;
 717                 bool log;
 718
 719                 mutex_lock(&d->vqs[i]->mutex);
 720                 log = log_all || vhost_has_feature(d->vqs[i], VHOST_F_LOG_ALL);
 721                 /* If ring is inactive, will check when it's enabled. */
 722                 if (d->vqs[i]->private_data)
 723                         ok = vq_memory_access_ok(d->vqs[i]->log_base,
 724                                                  umem, log);
 725                 else
 726                         ok = true;
 727                 mutex_unlock(&d->vqs[i]->mutex);
 728                 if (!ok)
 729                         return false;
 730         }
 731         return true;
 732 }
 733
 734 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
 735                           struct iovec iov[], int iov_size, int access);
 736
 737 static int vhost_copy_to_user(struct vhost_virtqueue *vq, void __user *to,
 738                               const void *from, unsigned size)
 739 {
 740         int ret;
 741
 742         if (!vq->iotlb)
 743                 return __copy_to_user(to, from, size);
 744         else {
 745                 /* This function should be called after iotlb
 746                  * prefetch, which means we're sure that all vq
 747                  * could be access through iotlb. So -EAGAIN should
 748                  * not happen in this case.
 749                  */
 750                 struct iov_iter t;
 751                 void __user *uaddr = vhost_vq_meta_fetch(vq,
 752                                      (u64)(uintptr_t)to, size,
 753                                      VHOST_ADDR_USED);
 754
 755                 if (uaddr)
 756                         return __copy_to_user(uaddr, from, size);
 757
 758                 ret = translate_desc(vq, (u64)(uintptr_t)to, size, vq->iotlb_iov,
 759                                      ARRAY_SIZE(vq->iotlb_iov),
 760                                      VHOST_ACCESS_WO);
 761                 if (ret < 0)
 762                         goto out;
 763                 iov_iter_init(&t, WRITE, vq->iotlb_iov, ret, size);
 764                 ret = copy_to_iter(from, size, &t);
 765                 if (ret == size)
 766                         ret = 0;
 767         }
 768 out:
 769         return ret;
 770 }
 771
 772 static int vhost_copy_from_user(struct vhost_virtqueue *vq, void *to,
 773                                 void __user *from, unsigned size)
 774 {
 775         int ret;
 776
 777         if (!vq->iotlb)
 778                 return __copy_from_user(to, from, size);
 779         else {
 780                 /* This function should be called after iotlb
 781                  * prefetch, which means we're sure that vq
 782                  * could be access through iotlb. So -EAGAIN should
 783                  * not happen in this case.
 784                  */
 785                 void __user *uaddr = vhost_vq_meta_fetch(vq,
 786                                      (u64)(uintptr_t)from, size,
 787                                      VHOST_ADDR_DESC);
 788                 struct iov_iter f;
 789
 790                 if (uaddr)
 791                         return __copy_from_user(to, uaddr, size);
 792
 793                 ret = translate_desc(vq, (u64)(uintptr_t)from, size, vq->iotlb_iov,
 794                                      ARRAY_SIZE(vq->iotlb_iov),
 795                                      VHOST_ACCESS_RO);
 796                 if (ret < 0) {
 797                         vq_err(vq, "IOTLB translation failure: uaddr "
 798                                "%p size 0x%llx\n", from,
 799                                (unsigned long long) size);
 800                         goto out;
 801                 }
 802                 iov_iter_init(&f, READ, vq->iotlb_iov, ret, size);
 803                 ret = copy_from_iter(to, size, &f);
 804                 if (ret == size)
 805                         ret = 0;
 806         }
 807
 808 out:
 809         return ret;
 810 }
 811
 812 static void __user *__vhost_get_user_slow(struct vhost_virtqueue *vq,
 813                                           void __user *addr, unsigned int size,
 814                                           int type)
 815 {
 816         int ret;
 817
 818         ret = translate_desc(vq, (u64)(uintptr_t)addr, size, vq->iotlb_iov,
 819                              ARRAY_SIZE(vq->iotlb_iov),
 820                              VHOST_ACCESS_RO);
 821         if (ret < 0) {
 822                 vq_err(vq, "IOTLB translation failure: uaddr "
 823                         "%p size 0x%llx\n", addr,
 824                         (unsigned long long) size);
 825                 return NULL;
 826         }
 827
 828         if (ret != 1 || vq->iotlb_iov[0].iov_len != size) {
 829                 vq_err(vq, "Non atomic userspace memory access: uaddr "
 830                         "%p size 0x%llx\n", addr,
 831                         (unsigned long long) size);
 832                 return NULL;
 833         }
 834
 835         return vq->iotlb_iov[0].iov_base;
 836 }
 837
 838 /* This function should be called after iotlb
 839  * prefetch, which means we're sure that vq
 840  * could be access through iotlb. So -EAGAIN should
 841  * not happen in this case.
 842  */
 843 static inline void __user *__vhost_get_user(struct vhost_virtqueue *vq,
 844                                             void *addr, unsigned int size,
 845                                             int type)
 846 {
 847         void __user *uaddr = vhost_vq_meta_fetch(vq,
 848                              (u64)(uintptr_t)addr, size, type);
 849         if (uaddr)
 850                 return uaddr;
 851
 852         return __vhost_get_user_slow(vq, addr, size, type);
 853 }
 854
 855 #define vhost_put_user(vq, x, ptr)              \
 856 ({ \
 857         int ret = -EFAULT; \
 858         if (!vq->iotlb) { \
 859                 ret = __put_user(x, ptr); \
 860         } else { \
 861                 __typeof__(ptr) to = \
 862                         (__typeof__(ptr)) __vhost_get_user(vq, ptr,     \
 863                                           sizeof(*ptr), VHOST_ADDR_USED); \
 864                 if (to != NULL) \
 865                         ret = __put_user(x, to); \
 866                 else \
 867                         ret = -EFAULT;  \
 868         } \
 869         ret; \
 870 })
 871
 872 #define vhost_get_user(vq, x, ptr, type)                \
 873 ({ \
 874         int ret; \
 875         if (!vq->iotlb) { \
 876                 ret = __get_user(x, ptr); \
 877         } else { \
 878                 __typeof__(ptr) from = \
 879                         (__typeof__(ptr)) __vhost_get_user(vq, ptr, \
 880                                                            sizeof(*ptr), \
 881                                                            type); \
 882                 if (from != NULL) \
 883                         ret = __get_user(x, from); \
 884                 else \
 885                         ret = -EFAULT; \
 886         } \
 887         ret; \
 888 })
 889
 890 #define vhost_get_avail(vq, x, ptr) \
 891         vhost_get_user(vq, x, ptr, VHOST_ADDR_AVAIL)
 892
 893 #define vhost_get_used(vq, x, ptr) \
 894         vhost_get_user(vq, x, ptr, VHOST_ADDR_USED)
 895
 896 static void vhost_dev_lock_vqs(struct vhost_dev *d)
 897 {
 898         int i = 0;
 899         for (i = 0; i < d->nvqs; ++i)
 900                 mutex_lock_nested(&d->vqs[i]->mutex, i);
 901 }
 902
 903 static void vhost_dev_unlock_vqs(struct vhost_dev *d)
 904 {
 905         int i = 0;
 906         for (i = 0; i < d->nvqs; ++i)
 907                 mutex_unlock(&d->vqs[i]->mutex);
 908 }
 909
 910 static int vhost_new_umem_range(struct vhost_umem *umem,
 911                                 u64 start, u64 size, u64 end,
 912                                 u64 userspace_addr, int perm)
 913 {
 914         struct vhost_umem_node *tmp, *node = kmalloc(sizeof(*node), GFP_ATOMIC);
 915
 916         if (!node)
 917                 return -ENOMEM;
 918
 919         if (umem->numem == max_iotlb_entries) {
 920                 tmp = list_first_entry(&umem->umem_list, typeof(*tmp), link);
 921                 vhost_umem_free(umem, tmp);
 922         }
 923
 924         node->start = start;
 925         node->size = size;
 926         node->last = end;
 927         node->userspace_addr = userspace_addr;
 928         node->perm = perm;
 929         INIT_LIST_HEAD(&node->link);
 930         list_add_tail(&node->link, &umem->umem_list);
 931         vhost_umem_interval_tree_insert(node, &umem->umem_tree);
 932         umem->numem++;
 933
 934         return 0;
 935 }
 936
 937 static void vhost_del_umem_range(struct vhost_umem *umem,
 938                                  u64 start, u64 end)
 939 {
 940         struct vhost_umem_node *node;
 941
 942         while ((node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
 943                                                            start, end)))
 944                 vhost_umem_free(umem, node);
 945 }
 946
 947 static void vhost_iotlb_notify_vq(struct vhost_dev *d,
 948                                   struct vhost_iotlb_msg *msg)
 949 {
 950         struct vhost_msg_node *node, *n;
 951
 952         spin_lock(&d->iotlb_lock);
 953
 954         list_for_each_entry_safe(node, n, &d->pending_list, node) {
 955                 struct vhost_iotlb_msg *vq_msg = &node->msg.iotlb;
 956                 if (msg->iova <= vq_msg->iova &&
 957                     msg->iova + msg->size - 1 >= vq_msg->iova &&
 958                     vq_msg->type == VHOST_IOTLB_MISS) {
 959                         vhost_poll_queue(&node->vq->poll);
 960                         list_del(&node->node);
 961                         kfree(node);
 962                 }
 963         }
 964
 965         spin_unlock(&d->iotlb_lock);
 966 }
 967
 968 static bool umem_access_ok(u64 uaddr, u64 size, int access)
 969 {
 970         unsigned long a = uaddr;
 971
 972         /* Make sure 64 bit math will not overflow. */
 973         if (vhost_overflow(uaddr, size))
 974                 return false;
 975
 976         if ((access & VHOST_ACCESS_RO) &&
 977             !access_ok((void __user *)a, size))
 978                 return false;
 979         if ((access & VHOST_ACCESS_WO) &&
 980             !access_ok((void __user *)a, size))
 981                 return false;
 982         return true;
 983 }
 984
 985 static int vhost_process_iotlb_msg(struct vhost_dev *dev,
 986                                    struct vhost_iotlb_msg *msg)
 987 {
 988         int ret = 0;
 989
 990         mutex_lock(&dev->mutex);
 991         vhost_dev_lock_vqs(dev);
 992         switch (msg->type) {
 993         case VHOST_IOTLB_UPDATE:
 994                 if (!dev->iotlb) {
 995                         ret = -EFAULT;
 996                         break;
 997                 }
 998                 if (!umem_access_ok(msg->uaddr, msg->size, msg->perm)) {
 999                         ret = -EFAULT;
1000                         break;
1001                 }
1002                 vhost_vq_meta_reset(dev);
1003                 if (vhost_new_umem_range(dev->iotlb, msg->iova, msg->size,
1004                                          msg->iova + msg->size - 1,
1005                                          msg->uaddr, msg->perm)) {
1006                         ret = -ENOMEM;
1007                         break;
1008                 }
1009                 vhost_iotlb_notify_vq(dev, msg);
1010                 break;
1011         case VHOST_IOTLB_INVALIDATE:
1012                 if (!dev->iotlb) {
1013                         ret = -EFAULT;
1014                         break;
1015                 }
1016                 vhost_vq_meta_reset(dev);
1017                 vhost_del_umem_range(dev->iotlb, msg->iova,
1018                                      msg->iova + msg->size - 1);
1019                 break;
1020         default:
1021                 ret = -EINVAL;
1022                 break;
1023         }
1024
1025         vhost_dev_unlock_vqs(dev);
1026         mutex_unlock(&dev->mutex);
1027
1028         return ret;
1029 }
1030 ssize_t vhost_chr_write_iter(struct vhost_dev *dev,
1031                              struct iov_iter *from)
1032 {
1033         struct vhost_iotlb_msg msg;
1034         size_t offset;
1035         int type, ret;
1036
1037         ret = copy_from_iter(&type, sizeof(type), from);
1038         if (ret != sizeof(type)) {
1039                 ret = -EINVAL;
1040                 goto done;
1041         }
1042
1043         switch (type) {
1044         case VHOST_IOTLB_MSG:
1045                 /* There maybe a hole after type for V1 message type,
1046                  * so skip it here.
1047                  */
1048                 offset = offsetof(struct vhost_msg, iotlb) - sizeof(int);
1049                 break;
1050         case VHOST_IOTLB_MSG_V2:
1051                 offset = sizeof(__u32);
1052                 break;
1053         default:
1054                 ret = -EINVAL;
1055                 goto done;
1056         }
1057
1058         iov_iter_advance(from, offset);
1059         ret = copy_from_iter(&msg, sizeof(msg), from);
1060         if (ret != sizeof(msg)) {
1061                 ret = -EINVAL;
1062                 goto done;
1063         }
1064         if (vhost_process_iotlb_msg(dev, &msg)) {
1065                 ret = -EFAULT;
1066                 goto done;
1067         }
1068
1069         ret = (type == VHOST_IOTLB_MSG) ? sizeof(struct vhost_msg) :
1070               sizeof(struct vhost_msg_v2);
1071 done:
1072         return ret;
1073 }
1074 EXPORT_SYMBOL(vhost_chr_write_iter);
1075
1076 __poll_t vhost_chr_poll(struct file *file, struct vhost_dev *dev,
1077                             poll_table *wait)
1078 {
1079         __poll_t mask = 0;
1080
1081         poll_wait(file, &dev->wait, wait);
1082
1083         if (!list_empty(&dev->read_list))
1084                 mask |= EPOLLIN | EPOLLRDNORM;
1085
1086         return mask;
1087 }
1088 EXPORT_SYMBOL(vhost_chr_poll);
1089
1090 ssize_t vhost_chr_read_iter(struct vhost_dev *dev, struct iov_iter *to,
1091                             int noblock)
1092 {
1093         DEFINE_WAIT(wait);
1094         struct vhost_msg_node *node;
1095         ssize_t ret = 0;
1096         unsigned size = sizeof(struct vhost_msg);
1097
1098         if (iov_iter_count(to) < size)
1099                 return 0;
1100
1101         while (1) {
1102                 if (!noblock)
1103                         prepare_to_wait(&dev->wait, &wait,
1104                                         TASK_INTERRUPTIBLE);
1105
1106                 node = vhost_dequeue_msg(dev, &dev->read_list);
1107                 if (node)
1108                         break;
1109                 if (noblock) {
1110                         ret = -EAGAIN;
1111                         break;
1112                 }
1113                 if (signal_pending(current)) {
1114                         ret = -ERESTARTSYS;
1115                         break;
1116                 }
1117                 if (!dev->iotlb) {
1118                         ret = -EBADFD;
1119                         break;
1120                 }
1121
1122                 schedule();
1123         }
1124
1125         if (!noblock)
1126                 finish_wait(&dev->wait, &wait);
1127
1128         if (node) {
1129                 struct vhost_iotlb_msg *msg;
1130                 void *start = &node->msg;
1131
1132                 switch (node->msg.type) {
1133                 case VHOST_IOTLB_MSG:
1134                         size = sizeof(node->msg);
1135                         msg = &node->msg.iotlb;
1136                         break;
1137                 case VHOST_IOTLB_MSG_V2:
1138                         size = sizeof(node->msg_v2);
1139                         msg = &node->msg_v2.iotlb;
1140                         break;
1141                 default:
1142                         BUG();
1143                         break;
1144                 }
1145
1146                 ret = copy_to_iter(start, size, to);
1147                 if (ret != size || msg->type != VHOST_IOTLB_MISS) {
1148                         kfree(node);
1149                         return ret;
1150                 }
1151                 vhost_enqueue_msg(dev, &dev->pending_list, node);
1152         }
1153
1154         return ret;
1155 }
1156 EXPORT_SYMBOL_GPL(vhost_chr_read_iter);
1157
1158 static int vhost_iotlb_miss(struct vhost_virtqueue *vq, u64 iova, int access)
1159 {
1160         struct vhost_dev *dev = vq->dev;
1161         struct vhost_msg_node *node;
1162         struct vhost_iotlb_msg *msg;
1163         bool v2 = vhost_backend_has_feature(vq, VHOST_BACKEND_F_IOTLB_MSG_V2);
1164
1165         node = vhost_new_msg(vq, v2 ? VHOST_IOTLB_MSG_V2 : VHOST_IOTLB_MSG);
1166         if (!node)
1167                 return -ENOMEM;
1168
1169         if (v2) {
1170                 node->msg_v2.type = VHOST_IOTLB_MSG_V2;
1171                 msg = &node->msg_v2.iotlb;
1172         } else {
1173                 msg = &node->msg.iotlb;
1174         }
1175
1176         msg->type = VHOST_IOTLB_MISS;
1177         msg->iova = iova;
1178         msg->perm = access;
1179
1180         vhost_enqueue_msg(dev, &dev->read_list, node);
1181
1182         return 0;
1183 }
1184
1185 static bool vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
1186                          struct vring_desc __user *desc,
1187                          struct vring_avail __user *avail,
1188                          struct vring_used __user *used)
1189
1190 {
1191         size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
1192
1193         return access_ok(desc, num * sizeof *desc) &&
1194                access_ok(avail,
1195                          sizeof *avail + num * sizeof *avail->ring + s) &&
1196                access_ok(used,
1197                         sizeof *used + num * sizeof *used->ring + s);
1198 }
1199
1200 static void vhost_vq_meta_update(struct vhost_virtqueue *vq,
1201                                  const struct vhost_umem_node *node,
1202                                  int type)
1203 {
1204         int access = (type == VHOST_ADDR_USED) ?
1205                      VHOST_ACCESS_WO : VHOST_ACCESS_RO;
1206
1207         if (likely(node->perm & access))
1208                 vq->meta_iotlb[type] = node;
1209 }
1210
1211 static bool iotlb_access_ok(struct vhost_virtqueue *vq,
1212                             int access, u64 addr, u64 len, int type)
1213 {
1214         const struct vhost_umem_node *node;
1215         struct vhost_umem *umem = vq->iotlb;
1216         u64 s = 0, size, orig_addr = addr, last = addr + len - 1;
1217
1218         if (vhost_vq_meta_fetch(vq, addr, len, type))
1219                 return true;
1220
1221         while (len > s) {
1222                 node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
1223                                                            addr,
1224                                                            last);
1225                 if (node == NULL || node->start > addr) {
1226                         vhost_iotlb_miss(vq, addr, access);
1227                         return false;
1228                 } else if (!(node->perm & access)) {
1229                         /* Report the possible access violation by
1230                          * request another translation from userspace.
1231                          */
1232                         return false;
1233                 }
1234
1235                 size = node->size - addr + node->start;
1236
1237                 if (orig_addr == addr && size >= len)
1238                         vhost_vq_meta_update(vq, node, type);
1239
1240                 s += size;
1241                 addr += size;
1242         }
1243
1244         return true;
1245 }
1246
1247 int vq_iotlb_prefetch(struct vhost_virtqueue *vq)
1248 {
1249         size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
1250         unsigned int num = vq->num;
1251
1252         if (!vq->iotlb)
1253                 return 1;
1254
1255         return iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->desc,
1256                                num * sizeof(*vq->desc), VHOST_ADDR_DESC) &&
1257                iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->avail,
1258                                sizeof *vq->avail +
1259                                num * sizeof(*vq->avail->ring) + s,
1260                                VHOST_ADDR_AVAIL) &&
1261                iotlb_access_ok(vq, VHOST_ACCESS_WO, (u64)(uintptr_t)vq->used,
1262                                sizeof *vq->used +
1263                                num * sizeof(*vq->used->ring) + s,
1264                                VHOST_ADDR_USED);
1265 }
1266 EXPORT_SYMBOL_GPL(vq_iotlb_prefetch);
1267
1268 /* Can we log writes? */
1269 /* Caller should have device mutex but not vq mutex */
1270 bool vhost_log_access_ok(struct vhost_dev *dev)
1271 {
1272         return memory_access_ok(dev, dev->umem, 1);
1273 }
1274 EXPORT_SYMBOL_GPL(vhost_log_access_ok);
1275
1276 /* Verify access for write logging. */
1277 /* Caller should have vq mutex and device mutex */
1278 static bool vq_log_access_ok(struct vhost_virtqueue *vq,
1279                              void __user *log_base)
1280 {
1281         size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
1282
1283         return vq_memory_access_ok(log_base, vq->umem,
1284                                    vhost_has_feature(vq, VHOST_F_LOG_ALL)) &&
1285                 (!vq->log_used || log_access_ok(log_base, vq->log_addr,
1286                                         sizeof *vq->used +
1287                                         vq->num * sizeof *vq->used->ring + s));
1288 }
1289
1290 /* Can we start vq? */
1291 /* Caller should have vq mutex and device mutex */
1292 bool vhost_vq_access_ok(struct vhost_virtqueue *vq)
1293 {
1294         if (!vq_log_access_ok(vq, vq->log_base))
1295                 return false;
1296
1297         /* Access validation occurs at prefetch time with IOTLB */
1298         if (vq->iotlb)
1299                 return true;
1300
1301         return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used);
1302 }
1303 EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
1304
1305 static struct vhost_umem *vhost_umem_alloc(void)
1306 {
1307         struct vhost_umem *umem = kvzalloc(sizeof(*umem), GFP_KERNEL);
1308
1309         if (!umem)
1310                 return NULL;
1311
1312         umem->umem_tree = RB_ROOT_CACHED;
1313         umem->numem = 0;
1314         INIT_LIST_HEAD(&umem->umem_list);
1315
1316         return umem;
1317 }
1318
1319 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
1320 {
1321         struct vhost_memory mem, *newmem;
1322         struct vhost_memory_region *region;
1323         struct vhost_umem *newumem, *oldumem;
1324         unsigned long size = offsetof(struct vhost_memory, regions);
1325         int i;
1326
1327         if (copy_from_user(&mem, m, size))
1328                 return -EFAULT;
1329         if (mem.padding)
1330                 return -EOPNOTSUPP;
1331         if (mem.nregions > max_mem_regions)
1332                 return -E2BIG;
1333         newmem = kvzalloc(struct_size(newmem, regions, mem.nregions),
1334                         GFP_KERNEL);
1335         if (!newmem)
1336                 return -ENOMEM;
1337
1338         memcpy(newmem, &mem, size);
1339         if (copy_from_user(newmem->regions, m->regions,
1340                            mem.nregions * sizeof *m->regions)) {
1341                 kvfree(newmem);
1342                 return -EFAULT;
1343         }
1344
1345         newumem = vhost_umem_alloc();
1346         if (!newumem) {
1347                 kvfree(newmem);
1348                 return -ENOMEM;
1349         }
1350
1351         for (region = newmem->regions;
1352              region < newmem->regions + mem.nregions;
1353              region++) {
1354                 if (vhost_new_umem_range(newumem,
1355                                          region->guest_phys_addr,
1356                                          region->memory_size,
1357                                          region->guest_phys_addr +
1358                                          region->memory_size - 1,
1359                                          region->userspace_addr,
1360                                          VHOST_ACCESS_RW))
1361                         goto err;
1362         }
1363
1364         if (!memory_access_ok(d, newumem, 0))
1365                 goto err;
1366
1367         oldumem = d->umem;
1368         d->umem = newumem;
1369
1370         /* All memory accesses are done under some VQ mutex. */
1371         for (i = 0; i < d->nvqs; ++i) {
1372                 mutex_lock(&d->vqs[i]->mutex);
1373                 d->vqs[i]->umem = newumem;
1374                 mutex_unlock(&d->vqs[i]->mutex);
1375         }
1376
1377         kvfree(newmem);
1378         vhost_umem_clean(oldumem);
1379         return 0;
1380
1381 err:
1382         vhost_umem_clean(newumem);
1383         kvfree(newmem);
1384         return -EFAULT;
1385 }
1386
1387 long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
1388 {
1389         struct file *eventfp, *filep = NULL;
1390         bool pollstart = false, pollstop = false;
1391         struct eventfd_ctx *ctx = NULL;
1392         u32 __user *idxp = argp;
1393         struct vhost_virtqueue *vq;
1394         struct vhost_vring_state s;
1395         struct vhost_vring_file f;
1396         struct vhost_vring_addr a;
1397         u32 idx;
1398         long r;
1399
1400         r = get_user(idx, idxp);
1401         if (r < 0)
1402                 return r;
1403         if (idx >= d->nvqs)
1404                 return -ENOBUFS;
1405
1406         idx = array_index_nospec(idx, d->nvqs);
1407         vq = d->vqs[idx];
1408
1409         mutex_lock(&vq->mutex);
1410
1411         switch (ioctl) {
1412         case VHOST_SET_VRING_NUM:
1413                 /* Resizing ring with an active backend?
1414                  * You don't want to do that. */
1415                 if (vq->private_data) {
1416                         r = -EBUSY;
1417                         break;
1418                 }
1419                 if (copy_from_user(&s, argp, sizeof s)) {
1420                         r = -EFAULT;
1421                         break;
1422                 }
1423                 if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) {
1424                         r = -EINVAL;
1425                         break;
1426                 }
1427                 vq->num = s.num;
1428                 break;
1429         case VHOST_SET_VRING_BASE:
1430                 /* Moving base with an active backend?
1431                  * You don't want to do that. */
1432                 if (vq->private_data) {
1433                         r = -EBUSY;
1434                         break;
1435                 }
1436                 if (copy_from_user(&s, argp, sizeof s)) {
1437                         r = -EFAULT;
1438                         break;
1439                 }
1440                 if (s.num > 0xffff) {
1441                         r = -EINVAL;
1442                         break;
1443                 }
1444                 vq->last_avail_idx = s.num;
1445                 /* Forget the cached index value. */
1446                 vq->avail_idx = vq->last_avail_idx;
1447                 break;
1448         case VHOST_GET_VRING_BASE:
1449                 s.index = idx;
1450                 s.num = vq->last_avail_idx;
1451                 if (copy_to_user(argp, &s, sizeof s))
1452                         r = -EFAULT;
1453                 break;
1454         case VHOST_SET_VRING_ADDR:
1455                 if (copy_from_user(&a, argp, sizeof a)) {
1456                         r = -EFAULT;
1457                         break;
1458                 }
1459                 if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) {
1460                         r = -EOPNOTSUPP;
1461                         break;
1462                 }
1463                 /* For 32bit, verify that the top 32bits of the user
1464                    data are set to zero. */
1465                 if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr ||
1466                     (u64)(unsigned long)a.used_user_addr != a.used_user_addr ||
1467                     (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) {
1468                         r = -EFAULT;
1469                         break;
1470                 }
1471
1472                 /* Make sure it's safe to cast pointers to vring types. */
1473                 BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE);
1474                 BUILD_BUG_ON(__alignof__ *vq->used > VRING_USED_ALIGN_SIZE);
1475                 if ((a.avail_user_addr & (VRING_AVAIL_ALIGN_SIZE - 1)) ||
1476                     (a.used_user_addr & (VRING_USED_ALIGN_SIZE - 1)) ||
1477                     (a.log_guest_addr & (VRING_USED_ALIGN_SIZE - 1))) {
1478                         r = -EINVAL;
1479                         break;
1480                 }
1481
1482                 /* We only verify access here if backend is configured.
1483                  * If it is not, we don't as size might not have been setup.
1484                  * We will verify when backend is configured. */
1485                 if (vq->private_data) {
1486                         if (!vq_access_ok(vq, vq->num,
1487                                 (void __user *)(unsigned long)a.desc_user_addr,
1488                                 (void __user *)(unsigned long)a.avail_user_addr,
1489                                 (void __user *)(unsigned long)a.used_user_addr)) {
1490                                 r = -EINVAL;
1491                                 break;
1492                         }
1493
1494                         /* Also validate log access for used ring if enabled. */
1495                         if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) &&
1496                             !log_access_ok(vq->log_base, a.log_guest_addr,
1497                                            sizeof *vq->used +
1498                                            vq->num * sizeof *vq->used->ring)) {
1499                                 r = -EINVAL;
1500                                 break;
1501                         }
1502                 }
1503
1504                 vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
1505                 vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
1506                 vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
1507                 vq->log_addr = a.log_guest_addr;
1508                 vq->used = (void __user *)(unsigned long)a.used_user_addr;
1509                 break;
1510         case VHOST_SET_VRING_KICK:
1511                 if (copy_from_user(&f, argp, sizeof f)) {
1512                         r = -EFAULT;
1513                         break;
1514                 }
1515                 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
1516                 if (IS_ERR(eventfp)) {
1517                         r = PTR_ERR(eventfp);
1518                         break;
1519                 }
1520                 if (eventfp != vq->kick) {
1521                         pollstop = (filep = vq->kick) != NULL;
1522                         pollstart = (vq->kick = eventfp) != NULL;
1523                 } else
1524                         filep = eventfp;
1525                 break;
1526         case VHOST_SET_VRING_CALL:
1527                 if (copy_from_user(&f, argp, sizeof f)) {
1528                         r = -EFAULT;
1529                         break;
1530                 }
1531                 ctx = f.fd == -1 ? NULL : eventfd_ctx_fdget(f.fd);
1532                 if (IS_ERR(ctx)) {
1533                         r = PTR_ERR(ctx);
1534                         break;
1535                 }
1536                 swap(ctx, vq->call_ctx);
1537                 break;
1538         case VHOST_SET_VRING_ERR:
1539                 if (copy_from_user(&f, argp, sizeof f)) {
1540                         r = -EFAULT;
1541                         break;
1542                 }
1543                 ctx = f.fd == -1 ? NULL : eventfd_ctx_fdget(f.fd);
1544                 if (IS_ERR(ctx)) {
1545                         r = PTR_ERR(ctx);
1546                         break;
1547                 }
1548                 swap(ctx, vq->error_ctx);
1549                 break;
1550         case VHOST_SET_VRING_ENDIAN:
1551                 r = vhost_set_vring_endian(vq, argp);
1552                 break;
1553         case VHOST_GET_VRING_ENDIAN:
1554                 r = vhost_get_vring_endian(vq, idx, argp);
1555                 break;
1556         case VHOST_SET_VRING_BUSYLOOP_TIMEOUT:
1557                 if (copy_from_user(&s, argp, sizeof(s))) {
1558                         r = -EFAULT;
1559                         break;
1560                 }
1561                 vq->busyloop_timeout = s.num;
1562                 break;
1563         case VHOST_GET_VRING_BUSYLOOP_TIMEOUT:
1564                 s.index = idx;
1565                 s.num = vq->busyloop_timeout;
1566                 if (copy_to_user(argp, &s, sizeof(s)))
1567                         r = -EFAULT;
1568                 break;
1569         default:
1570                 r = -ENOIOCTLCMD;
1571         }
1572
1573         if (pollstop && vq->handle_kick)
1574                 vhost_poll_stop(&vq->poll);
1575
1576         if (!IS_ERR_OR_NULL(ctx))
1577                 eventfd_ctx_put(ctx);
1578         if (filep)
1579                 fput(filep);
1580
1581         if (pollstart && vq->handle_kick)
1582                 r = vhost_poll_start(&vq->poll, vq->kick);
1583
1584         mutex_unlock(&vq->mutex);
1585
1586         if (pollstop && vq->handle_kick)
1587                 vhost_poll_flush(&vq->poll);
1588         return r;
1589 }
1590 EXPORT_SYMBOL_GPL(vhost_vring_ioctl);
1591
1592 int vhost_init_device_iotlb(struct vhost_dev *d, bool enabled)
1593 {
1594         struct vhost_umem *niotlb, *oiotlb;
1595         int i;
1596
1597         niotlb = vhost_umem_alloc();
1598         if (!niotlb)
1599                 return -ENOMEM;
1600
1601         oiotlb = d->iotlb;
1602         d->iotlb = niotlb;
1603
1604         for (i = 0; i < d->nvqs; ++i) {
1605                 struct vhost_virtqueue *vq = d->vqs[i];
1606
1607                 mutex_lock(&vq->mutex);
1608                 vq->iotlb = niotlb;
1609                 __vhost_vq_meta_reset(vq);
1610                 mutex_unlock(&vq->mutex);
1611         }
1612
1613         vhost_umem_clean(oiotlb);
1614
1615         return 0;
1616 }
1617 EXPORT_SYMBOL_GPL(vhost_init_device_iotlb);
1618
1619 /* Caller must have device mutex */
1620 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
1621 {
1622         struct eventfd_ctx *ctx;
1623         u64 p;
1624         long r;
1625         int i, fd;
1626
1627         /* If you are not the owner, you can become one */
1628         if (ioctl == VHOST_SET_OWNER) {
1629                 r = vhost_dev_set_owner(d);
1630                 goto done;
1631         }
1632
1633         /* You must be the owner to do anything else */
1634         r = vhost_dev_check_owner(d);
1635         if (r)
1636                 goto done;
1637
1638         switch (ioctl) {
1639         case VHOST_SET_MEM_TABLE:
1640                 r = vhost_set_memory(d, argp);
1641                 break;
1642         case VHOST_SET_LOG_BASE:
1643                 if (copy_from_user(&p, argp, sizeof p)) {
1644                         r = -EFAULT;
1645                         break;
1646                 }
1647                 if ((u64)(unsigned long)p != p) {
1648                         r = -EFAULT;
1649                         break;
1650                 }
1651                 for (i = 0; i < d->nvqs; ++i) {
1652                         struct vhost_virtqueue *vq;
1653                         void __user *base = (void __user *)(unsigned long)p;
1654                         vq = d->vqs[i];
1655                         mutex_lock(&vq->mutex);
1656                         /* If ring is inactive, will check when it's enabled. */
1657                         if (vq->private_data && !vq_log_access_ok(vq, base))
1658                                 r = -EFAULT;
1659                         else
1660                                 vq->log_base = base;
1661                         mutex_unlock(&vq->mutex);
1662                 }
1663                 break;
1664         case VHOST_SET_LOG_FD:
1665                 r = get_user(fd, (int __user *)argp);
1666                 if (r < 0)
1667                         break;
1668                 ctx = fd == -1 ? NULL : eventfd_ctx_fdget(fd);
1669                 if (IS_ERR(ctx)) {
1670                         r = PTR_ERR(ctx);
1671                         break;
1672                 }
1673                 swap(ctx, d->log_ctx);
1674                 for (i = 0; i < d->nvqs; ++i) {
1675                         mutex_lock(&d->vqs[i]->mutex);
1676                         d->vqs[i]->log_ctx = d->log_ctx;
1677                         mutex_unlock(&d->vqs[i]->mutex);
1678                 }
1679                 if (ctx)
1680                         eventfd_ctx_put(ctx);
1681                 break;
1682         default:
1683                 r = -ENOIOCTLCMD;
1684                 break;
1685         }
1686 done:
1687         return r;
1688 }
1689 EXPORT_SYMBOL_GPL(vhost_dev_ioctl);
1690
1691 /* TODO: This is really inefficient.  We need something like get_user()
1692  * (instruction directly accesses the data, with an exception table entry
1693  * returning -EFAULT). See Documentation/x86/exception-tables.txt.
1694  */
1695 static int set_bit_to_user(int nr, void __user *addr)
1696 {
1697         unsigned long log = (unsigned long)addr;
1698         struct page *page;
1699         void *base;
1700         int bit = nr + (log % PAGE_SIZE) * 8;
1701         int r;
1702
1703         r = get_user_pages_fast(log, 1, 1, &page);
1704         if (r < 0)
1705                 return r;
1706         BUG_ON(r != 1);
1707         base = kmap_atomic(page);
1708         set_bit(bit, base);
1709         kunmap_atomic(base);
1710         set_page_dirty_lock(page);
1711         put_page(page);
1712         return 0;
1713 }
1714
1715 static int log_write(void __user *log_base,
1716                      u64 write_address, u64 write_length)
1717 {
1718         u64 write_page = write_address / VHOST_PAGE_SIZE;
1719         int r;
1720
1721         if (!write_length)
1722                 return 0;
1723         write_length += write_address % VHOST_PAGE_SIZE;
1724         for (;;) {
1725                 u64 base = (u64)(unsigned long)log_base;
1726                 u64 log = base + write_page / 8;
1727                 int bit = write_page % 8;
1728                 if ((u64)(unsigned long)log != log)
1729                         return -EFAULT;
1730                 r = set_bit_to_user(bit, (void __user *)(unsigned long)log);
1731                 if (r < 0)
1732                         return r;
1733                 if (write_length <= VHOST_PAGE_SIZE)
1734                         break;
1735                 write_length -= VHOST_PAGE_SIZE;
1736                 write_page += 1;
1737         }
1738         return r;
1739 }
1740
1741 static int log_write_hva(struct vhost_virtqueue *vq, u64 hva, u64 len)
1742 {
1743         struct vhost_umem *umem = vq->umem;
1744         struct vhost_umem_node *u;
1745         u64 start, end, l, min;
1746         int r;
1747         bool hit = false;
1748
1749         while (len) {
1750                 min = len;
1751                 /* More than one GPAs can be mapped into a single HVA. So
1752                  * iterate all possible umems here to be safe.
1753                  */
1754                 list_for_each_entry(u, &umem->umem_list, link) {
1755                         if (u->userspace_addr > hva - 1 + len ||
1756                             u->userspace_addr - 1 + u->size < hva)
1757                                 continue;
1758                         start = max(u->userspace_addr, hva);
1759                         end = min(u->userspace_addr - 1 + u->size,
1760                                   hva - 1 + len);
1761                         l = end - start + 1;
1762                         r = log_write(vq->log_base,
1763                                       u->start + start - u->userspace_addr,
1764                                       l);
1765                         if (r < 0)
1766                                 return r;
1767                         hit = true;
1768                         min = min(l, min);
1769                 }
1770
1771                 if (!hit)
1772                         return -EFAULT;
1773
1774                 len -= min;
1775                 hva += min;
1776         }
1777
1778         return 0;
1779 }
1780
1781 static int log_used(struct vhost_virtqueue *vq, u64 used_offset, u64 len)
1782 {
1783         struct iovec iov[64];
1784         int i, ret;
1785
1786         if (!vq->iotlb)
1787                 return log_write(vq->log_base, vq->log_addr + used_offset, len);
1788
1789         ret = translate_desc(vq, (uintptr_t)vq->used + used_offset,
1790                              len, iov, 64, VHOST_ACCESS_WO);
1791         if (ret < 0)
1792                 return ret;
1793
1794         for (i = 0; i < ret; i++) {
1795                 ret = log_write_hva(vq, (uintptr_t)iov[i].iov_base,
1796                                     iov[i].iov_len);
1797                 if (ret)
1798                         return ret;
1799         }
1800
1801         return 0;
1802 }
1803
1804 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
1805                     unsigned int log_num, u64 len, struct iovec *iov, int count)
1806 {
1807         int i, r;
1808
1809         /* Make sure data written is seen before log. */
1810         smp_wmb();
1811
1812         if (vq->iotlb) {
1813                 for (i = 0; i < count; i++) {
1814                         r = log_write_hva(vq, (uintptr_t)iov[i].iov_base,
1815                                           iov[i].iov_len);
1816                         if (r < 0)
1817                                 return r;
1818                 }
1819                 return 0;
1820         }
1821
1822         for (i = 0; i < log_num; ++i) {
1823                 u64 l = min(log[i].len, len);
1824                 r = log_write(vq->log_base, log[i].addr, l);
1825                 if (r < 0)
1826                         return r;
1827                 len -= l;
1828                 if (!len) {
1829                         if (vq->log_ctx)
1830                                 eventfd_signal(vq->log_ctx, 1);
1831                         return 0;
1832                 }
1833         }
1834         /* Length written exceeds what we have stored. This is a bug. */
1835         BUG();
1836         return 0;
1837 }
1838 EXPORT_SYMBOL_GPL(vhost_log_write);
1839
1840 static int vhost_update_used_flags(struct vhost_virtqueue *vq)
1841 {
1842         void __user *used;
1843         if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->used_flags),
1844                            &vq->used->flags) < 0)
1845                 return -EFAULT;
1846         if (unlikely(vq->log_used)) {
1847                 /* Make sure the flag is seen before log. */
1848                 smp_wmb();
1849                 /* Log used flag write. */
1850                 used = &vq->used->flags;
1851                 log_used(vq, (used - (void __user *)vq->used),
1852                          sizeof vq->used->flags);
1853                 if (vq->log_ctx)
1854                         eventfd_signal(vq->log_ctx, 1);
1855         }
1856         return 0;
1857 }
1858
1859 static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event)
1860 {
1861         if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->avail_idx),
1862                            vhost_avail_event(vq)))
1863                 return -EFAULT;
1864         if (unlikely(vq->log_used)) {
1865                 void __user *used;
1866                 /* Make sure the event is seen before log. */
1867                 smp_wmb();
1868                 /* Log avail event write */
1869                 used = vhost_avail_event(vq);
1870                 log_used(vq, (used - (void __user *)vq->used),
1871                          sizeof *vhost_avail_event(vq));
1872                 if (vq->log_ctx)
1873                         eventfd_signal(vq->log_ctx, 1);
1874         }
1875         return 0;
1876 }
1877
1878 int vhost_vq_init_access(struct vhost_virtqueue *vq)
1879 {
1880         __virtio16 last_used_idx;
1881         int r;
1882         bool is_le = vq->is_le;
1883
1884         if (!vq->private_data)
1885                 return 0;
1886
1887         vhost_init_is_le(vq);
1888
1889         r = vhost_update_used_flags(vq);
1890         if (r)
1891                 goto err;
1892         vq->signalled_used_valid = false;
1893         if (!vq->iotlb &&
1894             !access_ok(&vq->used->idx, sizeof vq->used->idx)) {
1895                 r = -EFAULT;
1896                 goto err;
1897         }
1898         r = vhost_get_used(vq, last_used_idx, &vq->used->idx);
1899         if (r) {
1900                 vq_err(vq, "Can't access used idx at %p\n",
1901                        &vq->used->idx);
1902                 goto err;
1903         }
1904         vq->last_used_idx = vhost16_to_cpu(vq, last_used_idx);
1905         return 0;
1906
1907 err:
1908         vq->is_le = is_le;
1909         return r;
1910 }
1911 EXPORT_SYMBOL_GPL(vhost_vq_init_access);
1912
1913 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
1914                           struct iovec iov[], int iov_size, int access)
1915 {
1916         const struct vhost_umem_node *node;
1917         struct vhost_dev *dev = vq->dev;
1918         struct vhost_umem *umem = dev->iotlb ? dev->iotlb : dev->umem;
1919         struct iovec *_iov;
1920         u64 s = 0;
1921         int ret = 0;
1922
1923         while ((u64)len > s) {
1924                 u64 size;
1925                 if (unlikely(ret >= iov_size)) {
1926                         ret = -ENOBUFS;
1927                         break;
1928                 }
1929
1930                 node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
1931                                                         addr, addr + len - 1);
1932                 if (node == NULL || node->start > addr) {
1933                         if (umem != dev->iotlb) {
1934                                 ret = -EFAULT;
1935                                 break;
1936                         }
1937                         ret = -EAGAIN;
1938                         break;
1939                 } else if (!(node->perm & access)) {
1940                         ret = -EPERM;
1941                         break;
1942                 }
1943
1944                 _iov = iov + ret;
1945                 size = node->size - addr + node->start;
1946                 _iov->iov_len = min((u64)len - s, size);
1947                 _iov->iov_base = (void __user *)(unsigned long)
1948                         (node->userspace_addr + addr - node->start);
1949                 s += size;
1950                 addr += size;
1951                 ++ret;
1952         }
1953
1954         if (ret == -EAGAIN)
1955                 vhost_iotlb_miss(vq, addr, access);
1956         return ret;
1957 }
1958
1959 /* Each buffer in the virtqueues is actually a chain of descriptors.  This
1960  * function returns the next descriptor in the chain,
1961  * or -1U if we're at the end. */
1962 static unsigned next_desc(struct vhost_virtqueue *vq, struct vring_desc *desc)
1963 {
1964         unsigned int next;
1965
1966         /* If this descriptor says it doesn't chain, we're done. */
1967         if (!(desc->flags & cpu_to_vhost16(vq, VRING_DESC_F_NEXT)))
1968                 return -1U;
1969
1970         /* Check they're not leading us off end of descriptors. */
1971         next = vhost16_to_cpu(vq, READ_ONCE(desc->next));
1972         return next;
1973 }
1974
1975 static int get_indirect(struct vhost_virtqueue *vq,
1976                         struct iovec iov[], unsigned int iov_size,
1977                         unsigned int *out_num, unsigned int *in_num,
1978                         struct vhost_log *log, unsigned int *log_num,
1979                         struct vring_desc *indirect)
1980 {
1981         struct vring_desc desc;
1982         unsigned int i = 0, count, found = 0;
1983         u32 len = vhost32_to_cpu(vq, indirect->len);
1984         struct iov_iter from;
1985         int ret, access;
1986
1987         /* Sanity check */
1988         if (unlikely(len % sizeof desc)) {
1989                 vq_err(vq, "Invalid length in indirect descriptor: "
1990                        "len 0x%llx not multiple of 0x%zx\n",
1991                        (unsigned long long)len,
1992                        sizeof desc);
1993                 return -EINVAL;
1994         }
1995
1996         ret = translate_desc(vq, vhost64_to_cpu(vq, indirect->addr), len, vq->indirect,
1997                              UIO_MAXIOV, VHOST_ACCESS_RO);
1998         if (unlikely(ret < 0)) {
1999                 if (ret != -EAGAIN)
2000                         vq_err(vq, "Translation failure %d in indirect.\n", ret);
2001                 return ret;
2002         }
2003         iov_iter_init(&from, READ, vq->indirect, ret, len);
2004
2005         /* We will use the result as an address to read from, so most
2006          * architectures only need a compiler barrier here. */
2007         read_barrier_depends();
2008
2009         count = len / sizeof desc;
2010         /* Buffers are chained via a 16 bit next field, so
2011          * we can have at most 2^16 of these. */
2012         if (unlikely(count > USHRT_MAX + 1)) {
2013                 vq_err(vq, "Indirect buffer length too big: %d\n",
2014                        indirect->len);
2015                 return -E2BIG;
2016         }
2017
2018         do {
2019                 unsigned iov_count = *in_num + *out_num;
2020                 if (unlikely(++found > count)) {
2021                         vq_err(vq, "Loop detected: last one at %u "
2022                                "indirect size %u\n",
2023                                i, count);
2024                         return -EINVAL;
2025                 }
2026                 if (unlikely(!copy_from_iter_full(&desc, sizeof(desc), &from))) {
2027                         vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n",
2028                                i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
2029                         return -EINVAL;
2030                 }
2031                 if (unlikely(desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT))) {
2032                         vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n",
2033                                i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
2034                         return -EINVAL;
2035                 }
2036
2037                 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
2038                         access = VHOST_ACCESS_WO;
2039                 else
2040                         access = VHOST_ACCESS_RO;
2041
2042                 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
2043                                      vhost32_to_cpu(vq, desc.len), iov + iov_count,
2044                                      iov_size - iov_count, access);
2045                 if (unlikely(ret < 0)) {
2046                         if (ret != -EAGAIN)
2047                                 vq_err(vq, "Translation failure %d indirect idx %d\n",
2048                                         ret, i);
2049                         return ret;
2050                 }
2051                 /* If this is an input descriptor, increment that count. */
2052                 if (access == VHOST_ACCESS_WO) {
2053                         *in_num += ret;
2054                         if (unlikely(log)) {
2055                                 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
2056                                 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
2057                                 ++*log_num;
2058                         }
2059                 } else {
2060                         /* If it's an output descriptor, they're all supposed
2061                          * to come before any input descriptors. */
2062                         if (unlikely(*in_num)) {
2063                                 vq_err(vq, "Indirect descriptor "
2064                                        "has out after in: idx %d\n", i);
2065                                 return -EINVAL;
2066                         }
2067                         *out_num += ret;
2068                 }
2069         } while ((i = next_desc(vq, &desc)) != -1);
2070         return 0;
2071 }
2072
2073 /* This looks in the virtqueue and for the first available buffer, and converts
2074  * it to an iovec for convenient access.  Since descriptors consist of some
2075  * number of output then some number of input descriptors, it's actually two
2076  * iovecs, but we pack them into one and note how many of each there were.
2077  *
2078  * This function returns the descriptor number found, or vq->num (which is
2079  * never a valid descriptor number) if none was found.  A negative code is
2080  * returned on error. */
2081 int vhost_get_vq_desc(struct vhost_virtqueue *vq,
2082                       struct iovec iov[], unsigned int iov_size,
2083                       unsigned int *out_num, unsigned int *in_num,
2084                       struct vhost_log *log, unsigned int *log_num)
2085 {
2086         struct vring_desc desc;
2087         unsigned int i, head, found = 0;
2088         u16 last_avail_idx;
2089         __virtio16 avail_idx;
2090         __virtio16 ring_head;
2091         int ret, access;
2092
2093         /* Check it isn't doing very strange things with descriptor numbers. */
2094         last_avail_idx = vq->last_avail_idx;
2095
2096         if (vq->avail_idx == vq->last_avail_idx) {
2097                 if (unlikely(vhost_get_avail(vq, avail_idx, &vq->avail->idx))) {
2098                         vq_err(vq, "Failed to access avail idx at %p\n",
2099                                 &vq->avail->idx);
2100                         return -EFAULT;
2101                 }
2102                 vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
2103
2104                 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
2105                         vq_err(vq, "Guest moved used index from %u to %u",
2106                                 last_avail_idx, vq->avail_idx);
2107                         return -EFAULT;
2108                 }
2109
2110                 /* If there's nothing new since last we looked, return
2111                  * invalid.
2112                  */
2113                 if (vq->avail_idx == last_avail_idx)
2114                         return vq->num;
2115
2116                 /* Only get avail ring entries after they have been
2117                  * exposed by guest.
2118                  */
2119                 smp_rmb();
2120         }
2121
2122         /* Grab the next descriptor number they're advertising, and increment
2123          * the index we've seen. */
2124         if (unlikely(vhost_get_avail(vq, ring_head,
2125                      &vq->avail->ring[last_avail_idx & (vq->num - 1)]))) {
2126                 vq_err(vq, "Failed to read head: idx %d address %p\n",
2127                        last_avail_idx,
2128                        &vq->avail->ring[last_avail_idx % vq->num]);
2129                 return -EFAULT;
2130         }
2131
2132         head = vhost16_to_cpu(vq, ring_head);
2133
2134         /* If their number is silly, that's an error. */
2135         if (unlikely(head >= vq->num)) {
2136                 vq_err(vq, "Guest says index %u > %u is available",
2137                        head, vq->num);
2138                 return -EINVAL;
2139         }
2140
2141         /* When we start there are none of either input nor output. */
2142         *out_num = *in_num = 0;
2143         if (unlikely(log))
2144                 *log_num = 0;
2145
2146         i = head;
2147         do {
2148                 unsigned iov_count = *in_num + *out_num;
2149                 if (unlikely(i >= vq->num)) {
2150                         vq_err(vq, "Desc index is %u > %u, head = %u",
2151                                i, vq->num, head);
2152                         return -EINVAL;
2153                 }
2154                 if (unlikely(++found > vq->num)) {
2155                         vq_err(vq, "Loop detected: last one at %u "
2156                                "vq size %u head %u\n",
2157                                i, vq->num, head);
2158                         return -EINVAL;
2159                 }
2160                 ret = vhost_copy_from_user(vq, &desc, vq->desc + i,
2161                                            sizeof desc);
2162                 if (unlikely(ret)) {
2163                         vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
2164                                i, vq->desc + i);
2165                         return -EFAULT;
2166                 }
2167                 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT)) {
2168                         ret = get_indirect(vq, iov, iov_size,
2169                                            out_num, in_num,
2170                                            log, log_num, &desc);
2171                         if (unlikely(ret < 0)) {
2172                                 if (ret != -EAGAIN)
2173                                         vq_err(vq, "Failure detected "
2174                                                 "in indirect descriptor at idx %d\n", i);
2175                                 return ret;
2176                         }
2177                         continue;
2178                 }
2179
2180                 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
2181                         access = VHOST_ACCESS_WO;
2182                 else
2183                         access = VHOST_ACCESS_RO;
2184                 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
2185                                      vhost32_to_cpu(vq, desc.len), iov + iov_count,
2186                                      iov_size - iov_count, access);
2187                 if (unlikely(ret < 0)) {
2188                         if (ret != -EAGAIN)
2189                                 vq_err(vq, "Translation failure %d descriptor idx %d\n",
2190                                         ret, i);
2191                         return ret;
2192                 }
2193                 if (access == VHOST_ACCESS_WO) {
2194                         /* If this is an input descriptor,
2195                          * increment that count. */
2196                         *in_num += ret;
2197                         if (unlikely(log)) {
2198                                 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
2199                                 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
2200                                 ++*log_num;
2201                         }
2202                 } else {
2203                         /* If it's an output descriptor, they're all supposed
2204                          * to come before any input descriptors. */
2205                         if (unlikely(*in_num)) {
2206                                 vq_err(vq, "Descriptor has out after in: "
2207                                        "idx %d\n", i);
2208                                 return -EINVAL;
2209                         }
2210                         *out_num += ret;
2211                 }
2212         } while ((i = next_desc(vq, &desc)) != -1);
2213
2214         /* On success, increment avail index. */
2215         vq->last_avail_idx++;
2216
2217         /* Assume notifications from guest are disabled at this point,
2218          * if they aren't we would need to update avail_event index. */
2219         BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
2220         return head;
2221 }
2222 EXPORT_SYMBOL_GPL(vhost_get_vq_desc);
2223
2224 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
2225 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
2226 {
2227         vq->last_avail_idx -= n;
2228 }
2229 EXPORT_SYMBOL_GPL(vhost_discard_vq_desc);
2230
2231 /* After we've used one of their buffers, we tell them about it.  We'll then
2232  * want to notify the guest, using eventfd. */
2233 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
2234 {
2235         struct vring_used_elem heads = {
2236                 cpu_to_vhost32(vq, head),
2237                 cpu_to_vhost32(vq, len)
2238         };
2239
2240         return vhost_add_used_n(vq, &heads, 1);
2241 }
2242 EXPORT_SYMBOL_GPL(vhost_add_used);
2243
2244 static int __vhost_add_used_n(struct vhost_virtqueue *vq,
2245                             struct vring_used_elem *heads,
2246                             unsigned count)
2247 {
2248         struct vring_used_elem __user *used;
2249         u16 old, new;
2250         int start;
2251
2252         start = vq->last_used_idx & (vq->num - 1);
2253         used = vq->used->ring + start;
2254         if (count == 1) {
2255                 if (vhost_put_user(vq, heads[0].id, &used->id)) {
2256                         vq_err(vq, "Failed to write used id");
2257                         return -EFAULT;
2258                 }
2259                 if (vhost_put_user(vq, heads[0].len, &used->len)) {
2260                         vq_err(vq, "Failed to write used len");
2261                         return -EFAULT;
2262                 }
2263         } else if (vhost_copy_to_user(vq, used, heads, count * sizeof *used)) {
2264                 vq_err(vq, "Failed to write used");
2265                 return -EFAULT;
2266         }
2267         if (unlikely(vq->log_used)) {
2268                 /* Make sure data is seen before log. */
2269                 smp_wmb();
2270                 /* Log used ring entry write. */
2271                 log_used(vq, ((void __user *)used - (void __user *)vq->used),
2272                          count * sizeof *used);
2273         }
2274         old = vq->last_used_idx;
2275         new = (vq->last_used_idx += count);
2276         /* If the driver never bothers to signal in a very long while,
2277          * used index might wrap around. If that happens, invalidate
2278          * signalled_used index we stored. TODO: make sure driver
2279          * signals at least once in 2^16 and remove this. */
2280         if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old)))
2281                 vq->signalled_used_valid = false;
2282         return 0;
2283 }
2284
2285 /* After we've used one of their buffers, we tell them about it.  We'll then
2286  * want to notify the guest, using eventfd. */
2287 int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
2288                      unsigned count)
2289 {
2290         int start, n, r;
2291
2292         start = vq->last_used_idx & (vq->num - 1);
2293         n = vq->num - start;
2294         if (n < count) {
2295                 r = __vhost_add_used_n(vq, heads, n);
2296                 if (r < 0)
2297                         return r;
2298                 heads += n;
2299                 count -= n;
2300         }
2301         r = __vhost_add_used_n(vq, heads, count);
2302
2303         /* Make sure buffer is written before we update index. */
2304         smp_wmb();
2305         if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->last_used_idx),
2306                            &vq->used->idx)) {
2307                 vq_err(vq, "Failed to increment used idx");
2308                 return -EFAULT;
2309         }
2310         if (unlikely(vq->log_used)) {
2311                 /* Make sure used idx is seen before log. */
2312                 smp_wmb();
2313                 /* Log used index update. */
2314                 log_used(vq, offsetof(struct vring_used, idx),
2315                          sizeof vq->used->idx);
2316                 if (vq->log_ctx)
2317                         eventfd_signal(vq->log_ctx, 1);
2318         }
2319         return r;
2320 }
2321 EXPORT_SYMBOL_GPL(vhost_add_used_n);
2322
2323 static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2324 {
2325         __u16 old, new;
2326         __virtio16 event;
2327         bool v;
2328         /* Flush out used index updates. This is paired
2329          * with the barrier that the Guest executes when enabling
2330          * interrupts. */
2331         smp_mb();
2332
2333         if (vhost_has_feature(vq, VIRTIO_F_NOTIFY_ON_EMPTY) &&
2334             unlikely(vq->avail_idx == vq->last_avail_idx))
2335                 return true;
2336
2337         if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2338                 __virtio16 flags;
2339                 if (vhost_get_avail(vq, flags, &vq->avail->flags)) {
2340                         vq_err(vq, "Failed to get flags");
2341                         return true;
2342                 }
2343                 return !(flags & cpu_to_vhost16(vq, VRING_AVAIL_F_NO_INTERRUPT));
2344         }
2345         old = vq->signalled_used;
2346         v = vq->signalled_used_valid;
2347         new = vq->signalled_used = vq->last_used_idx;
2348         vq->signalled_used_valid = true;
2349
2350         if (unlikely(!v))
2351                 return true;
2352
2353         if (vhost_get_avail(vq, event, vhost_used_event(vq))) {
2354                 vq_err(vq, "Failed to get used event idx");
2355                 return true;
2356         }
2357         return vring_need_event(vhost16_to_cpu(vq, event), new, old);
2358 }
2359
2360 /* This actually signals the guest, using eventfd. */
2361 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2362 {
2363         /* Signal the Guest tell them we used something up. */
2364         if (vq->call_ctx && vhost_notify(dev, vq))
2365                 eventfd_signal(vq->call_ctx, 1);
2366 }
2367 EXPORT_SYMBOL_GPL(vhost_signal);
2368
2369 /* And here's the combo meal deal.  Supersize me! */
2370 void vhost_add_used_and_signal(struct vhost_dev *dev,
2371                                struct vhost_virtqueue *vq,
2372                                unsigned int head, int len)
2373 {
2374         vhost_add_used(vq, head, len);
2375         vhost_signal(dev, vq);
2376 }
2377 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal);
2378
2379 /* multi-buffer version of vhost_add_used_and_signal */
2380 void vhost_add_used_and_signal_n(struct vhost_dev *dev,
2381                                  struct vhost_virtqueue *vq,
2382                                  struct vring_used_elem *heads, unsigned count)
2383 {
2384         vhost_add_used_n(vq, heads, count);
2385         vhost_signal(dev, vq);
2386 }
2387 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n);
2388
2389 /* return true if we're sure that avaiable ring is empty */
2390 bool vhost_vq_avail_empty(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2391 {
2392         __virtio16 avail_idx;
2393         int r;
2394
2395         if (vq->avail_idx != vq->last_avail_idx)
2396                 return false;
2397
2398         r = vhost_get_avail(vq, avail_idx, &vq->avail->idx);
2399         if (unlikely(r))
2400                 return false;
2401         vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
2402
2403         return vq->avail_idx == vq->last_avail_idx;
2404 }
2405 EXPORT_SYMBOL_GPL(vhost_vq_avail_empty);
2406
2407 /* OK, now we need to know about added descriptors. */
2408 bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2409 {
2410         __virtio16 avail_idx;
2411         int r;
2412
2413         if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
2414                 return false;
2415         vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
2416         if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2417                 r = vhost_update_used_flags(vq);
2418                 if (r) {
2419                         vq_err(vq, "Failed to enable notification at %p: %d\n",
2420                                &vq->used->flags, r);
2421                         return false;
2422                 }
2423         } else {
2424                 r = vhost_update_avail_event(vq, vq->avail_idx);
2425                 if (r) {
2426                         vq_err(vq, "Failed to update avail event index at %p: %d\n",
2427                                vhost_avail_event(vq), r);
2428                         return false;
2429                 }
2430         }
2431         /* They could have slipped one in as we were doing that: make
2432          * sure it's written, then check again. */
2433         smp_mb();
2434         r = vhost_get_avail(vq, avail_idx, &vq->avail->idx);
2435         if (r) {
2436                 vq_err(vq, "Failed to check avail idx at %p: %d\n",
2437                        &vq->avail->idx, r);
2438                 return false;
2439         }
2440
2441         return vhost16_to_cpu(vq, avail_idx) != vq->avail_idx;
2442 }
2443 EXPORT_SYMBOL_GPL(vhost_enable_notify);
2444
2445 /* We don't need to be notified again. */
2446 void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2447 {
2448         int r;
2449
2450         if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
2451                 return;
2452         vq->used_flags |= VRING_USED_F_NO_NOTIFY;
2453         if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2454                 r = vhost_update_used_flags(vq);
2455                 if (r)
2456                         vq_err(vq, "Failed to enable notification at %p: %d\n",
2457                                &vq->used->flags, r);
2458         }
2459 }
2460 EXPORT_SYMBOL_GPL(vhost_disable_notify);
2461
2462 /* Create a new message. */
2463 struct vhost_msg_node *vhost_new_msg(struct vhost_virtqueue *vq, int type)
2464 {
2465         struct vhost_msg_node *node = kmalloc(sizeof *node, GFP_KERNEL);
2466         if (!node)
2467                 return NULL;
2468
2469         /* Make sure all padding within the structure is initialized. */
2470         memset(&node->msg, 0, sizeof node->msg);
2471         node->vq = vq;
2472         node->msg.type = type;
2473         return node;
2474 }
2475 EXPORT_SYMBOL_GPL(vhost_new_msg);
2476
2477 void vhost_enqueue_msg(struct vhost_dev *dev, struct list_head *head,
2478                        struct vhost_msg_node *node)
2479 {
2480         spin_lock(&dev->iotlb_lock);
2481         list_add_tail(&node->node, head);
2482         spin_unlock(&dev->iotlb_lock);
2483
2484         wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
2485 }
2486 EXPORT_SYMBOL_GPL(vhost_enqueue_msg);
2487
2488 struct vhost_msg_node *vhost_dequeue_msg(struct vhost_dev *dev,
2489                                          struct list_head *head)
2490 {
2491         struct vhost_msg_node *node = NULL;
2492
2493         spin_lock(&dev->iotlb_lock);
2494         if (!list_empty(head)) {
2495                 node = list_first_entry(head, struct vhost_msg_node,
2496                                         node);
2497                 list_del(&node->node);
2498         }
2499         spin_unlock(&dev->iotlb_lock);
2500
2501         return node;
2502 }
2503 EXPORT_SYMBOL_GPL(vhost_dequeue_msg);
2504
2505
2506 static int __init vhost_init(void)
2507 {
2508         return 0;
2509 }
2510
2511 static void __exit vhost_exit(void)
2512 {
2513 }
2514
2515 module_init(vhost_init);
2516 module_exit(vhost_exit);
2517
2518 MODULE_VERSION("0.0.1");
2519 MODULE_LICENSE("GPL v2");
2520 MODULE_AUTHOR("Michael S. Tsirkin");
2521 MODULE_DESCRIPTION("Host kernel accelerator for virtio");