drivers/vhost/vhost.c

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