drivers/vhost/vhost.c

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