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
  31 #include "vhost.h"
  32
  33 static ushort max_mem_regions = 64;
  34 module_param(max_mem_regions, ushort, 0444);
  35 MODULE_PARM_DESC(max_mem_regions,
  36         "Maximum number of memory regions in memory map. (default: 64)");
  37
  38 enum {
  39         VHOST_MEMORY_F_LOG = 0x1,
  40 };
  41
  42 #define vhost_used_event(vq) ((__virtio16 __user *)&vq->avail->ring[vq->num])
  43 #define vhost_avail_event(vq) ((__virtio16 __user *)&vq->used->ring[vq->num])
  44
  45 #ifdef CONFIG_VHOST_CROSS_ENDIAN_LEGACY
  46 static void vhost_disable_cross_endian(struct vhost_virtqueue *vq)
  47 {
  48         vq->user_be = !virtio_legacy_is_little_endian();
  49 }
  50
  51 static void vhost_enable_cross_endian_big(struct vhost_virtqueue *vq)
  52 {
  53         vq->user_be = true;
  54 }
  55
  56 static void vhost_enable_cross_endian_little(struct vhost_virtqueue *vq)
  57 {
  58         vq->user_be = false;
  59 }
  60
  61 static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp)
  62 {
  63         struct vhost_vring_state s;
  64
  65         if (vq->private_data)
  66                 return -EBUSY;
  67
  68         if (copy_from_user(&s, argp, sizeof(s)))
  69                 return -EFAULT;
  70
  71         if (s.num != VHOST_VRING_LITTLE_ENDIAN &&
  72             s.num != VHOST_VRING_BIG_ENDIAN)
  73                 return -EINVAL;
  74
  75         if (s.num == VHOST_VRING_BIG_ENDIAN)
  76                 vhost_enable_cross_endian_big(vq);
  77         else
  78                 vhost_enable_cross_endian_little(vq);
  79
  80         return 0;
  81 }
  82
  83 static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx,
  84                                    int __user *argp)
  85 {
  86         struct vhost_vring_state s = {
  87                 .index = idx,
  88                 .num = vq->user_be
  89         };
  90
  91         if (copy_to_user(argp, &s, sizeof(s)))
  92                 return -EFAULT;
  93
  94         return 0;
  95 }
  96
  97 static void vhost_init_is_le(struct vhost_virtqueue *vq)
  98 {
  99         /* Note for legacy virtio: user_be is initialized at reset time
 100          * according to the host endianness. If userspace does not set an
 101          * explicit endianness, the default behavior is native endian, as
 102          * expected by legacy virtio.
 103          */
 104         vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1) || !vq->user_be;
 105 }
 106 #else
 107 static void vhost_disable_cross_endian(struct vhost_virtqueue *vq)
 108 {
 109 }
 110
 111 static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp)
 112 {
 113         return -ENOIOCTLCMD;
 114 }
 115
 116 static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx,
 117                                    int __user *argp)
 118 {
 119         return -ENOIOCTLCMD;
 120 }
 121
 122 static void vhost_init_is_le(struct vhost_virtqueue *vq)
 123 {
 124         if (vhost_has_feature(vq, VIRTIO_F_VERSION_1))
 125                 vq->is_le = true;
 126 }
 127 #endif /* CONFIG_VHOST_CROSS_ENDIAN_LEGACY */
 128
 129 static void vhost_reset_is_le(struct vhost_virtqueue *vq)
 130 {
 131         vq->is_le = virtio_legacy_is_little_endian();
 132 }
 133
 134 struct vhost_flush_struct {
 135         struct vhost_work work;
 136         struct completion wait_event;
 137 };
 138
 139 static void vhost_flush_work(struct vhost_work *work)
 140 {
 141         struct vhost_flush_struct *s;
 142
 143         s = container_of(work, struct vhost_flush_struct, work);
 144         complete(&s->wait_event);
 145 }
 146
 147 static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh,
 148                             poll_table *pt)
 149 {
 150         struct vhost_poll *poll;
 151
 152         poll = container_of(pt, struct vhost_poll, table);
 153         poll->wqh = wqh;
 154         add_wait_queue(wqh, &poll->wait);
 155 }
 156
 157 static int vhost_poll_wakeup(wait_queue_t *wait, unsigned mode, int sync,
 158                              void *key)
 159 {
 160         struct vhost_poll *poll = container_of(wait, struct vhost_poll, wait);
 161
 162         if (!((unsigned long)key & poll->mask))
 163                 return 0;
 164
 165         vhost_poll_queue(poll);
 166         return 0;
 167 }
 168
 169 void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn)
 170 {
 171         clear_bit(VHOST_WORK_QUEUED, &work->flags);
 172         work->fn = fn;
 173         init_waitqueue_head(&work->done);
 174 }
 175 EXPORT_SYMBOL_GPL(vhost_work_init);
 176
 177 /* Init poll structure */
 178 void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
 179                      unsigned long mask, struct vhost_dev *dev)
 180 {
 181         init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup);
 182         init_poll_funcptr(&poll->table, vhost_poll_func);
 183         poll->mask = mask;
 184         poll->dev = dev;
 185         poll->wqh = NULL;
 186
 187         vhost_work_init(&poll->work, fn);
 188 }
 189 EXPORT_SYMBOL_GPL(vhost_poll_init);
 190
 191 /* Start polling a file. We add ourselves to file's wait queue. The caller must
 192  * keep a reference to a file until after vhost_poll_stop is called. */
 193 int vhost_poll_start(struct vhost_poll *poll, struct file *file)
 194 {
 195         unsigned long mask;
 196         int ret = 0;
 197
 198         if (poll->wqh)
 199                 return 0;
 200
 201         mask = file->f_op->poll(file, &poll->table);
 202         if (mask)
 203                 vhost_poll_wakeup(&poll->wait, 0, 0, (void *)mask);
 204         if (mask & POLLERR) {
 205                 if (poll->wqh)
 206                         remove_wait_queue(poll->wqh, &poll->wait);
 207                 ret = -EINVAL;
 208         }
 209
 210         return ret;
 211 }
 212 EXPORT_SYMBOL_GPL(vhost_poll_start);
 213
 214 /* Stop polling a file. After this function returns, it becomes safe to drop the
 215  * file reference. You must also flush afterwards. */
 216 void vhost_poll_stop(struct vhost_poll *poll)
 217 {
 218         if (poll->wqh) {
 219                 remove_wait_queue(poll->wqh, &poll->wait);
 220                 poll->wqh = NULL;
 221         }
 222 }
 223 EXPORT_SYMBOL_GPL(vhost_poll_stop);
 224
 225 void vhost_work_flush(struct vhost_dev *dev, struct vhost_work *work)
 226 {
 227         struct vhost_flush_struct flush;
 228
 229         if (dev->worker) {
 230                 init_completion(&flush.wait_event);
 231                 vhost_work_init(&flush.work, vhost_flush_work);
 232
 233                 vhost_work_queue(dev, &flush.work);
 234                 wait_for_completion(&flush.wait_event);
 235         }
 236 }
 237 EXPORT_SYMBOL_GPL(vhost_work_flush);
 238
 239 /* Flush any work that has been scheduled. When calling this, don't hold any
 240  * locks that are also used by the callback. */
 241 void vhost_poll_flush(struct vhost_poll *poll)
 242 {
 243         vhost_work_flush(poll->dev, &poll->work);
 244 }
 245 EXPORT_SYMBOL_GPL(vhost_poll_flush);
 246
 247 void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work)
 248 {
 249         if (!dev->worker)
 250                 return;
 251
 252         if (!test_and_set_bit(VHOST_WORK_QUEUED, &work->flags)) {
 253                 /* We can only add the work to the list after we're
 254                  * sure it was not in the list.
 255                  */
 256                 smp_mb();
 257                 llist_add(&work->node, &dev->work_list);
 258                 wake_up_process(dev->worker);
 259         }
 260 }
 261 EXPORT_SYMBOL_GPL(vhost_work_queue);
 262
 263 /* A lockless hint for busy polling code to exit the loop */
 264 bool vhost_has_work(struct vhost_dev *dev)
 265 {
 266         return !llist_empty(&dev->work_list);
 267 }
 268 EXPORT_SYMBOL_GPL(vhost_has_work);
 269
 270 void vhost_poll_queue(struct vhost_poll *poll)
 271 {
 272         vhost_work_queue(poll->dev, &poll->work);
 273 }
 274 EXPORT_SYMBOL_GPL(vhost_poll_queue);
 275
 276 static void vhost_vq_reset(struct vhost_dev *dev,
 277                            struct vhost_virtqueue *vq)
 278 {
 279         vq->num = 1;
 280         vq->desc = NULL;
 281         vq->avail = NULL;
 282         vq->used = NULL;
 283         vq->last_avail_idx = 0;
 284         vq->avail_idx = 0;
 285         vq->last_used_idx = 0;
 286         vq->signalled_used = 0;
 287         vq->signalled_used_valid = false;
 288         vq->used_flags = 0;
 289         vq->log_used = false;
 290         vq->log_addr = -1ull;
 291         vq->private_data = NULL;
 292         vq->acked_features = 0;
 293         vq->log_base = NULL;
 294         vq->error_ctx = NULL;
 295         vq->error = NULL;
 296         vq->kick = NULL;
 297         vq->call_ctx = NULL;
 298         vq->call = NULL;
 299         vq->log_ctx = NULL;
 300         vq->memory = NULL;
 301         vhost_reset_is_le(vq);
 302         vhost_disable_cross_endian(vq);
 303         vq->busyloop_timeout = 0;
 304 }
 305
 306 static int vhost_worker(void *data)
 307 {
 308         struct vhost_dev *dev = data;
 309         struct vhost_work *work, *work_next;
 310         struct llist_node *node;
 311         mm_segment_t oldfs = get_fs();
 312
 313         set_fs(USER_DS);
 314         use_mm(dev->mm);
 315
 316         for (;;) {
 317                 /* mb paired w/ kthread_stop */
 318                 set_current_state(TASK_INTERRUPTIBLE);
 319
 320                 if (kthread_should_stop()) {
 321                         __set_current_state(TASK_RUNNING);
 322                         break;
 323                 }
 324
 325                 node = llist_del_all(&dev->work_list);
 326                 if (!node)
 327                         schedule();
 328
 329                 node = llist_reverse_order(node);
 330                 /* make sure flag is seen after deletion */
 331                 smp_wmb();
 332                 llist_for_each_entry_safe(work, work_next, node, node) {
 333                         clear_bit(VHOST_WORK_QUEUED, &work->flags);
 334                         __set_current_state(TASK_RUNNING);
 335                         work->fn(work);
 336                         if (need_resched())
 337                                 schedule();
 338                 }
 339         }
 340         unuse_mm(dev->mm);
 341         set_fs(oldfs);
 342         return 0;
 343 }
 344
 345 static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq)
 346 {
 347         kfree(vq->indirect);
 348         vq->indirect = NULL;
 349         kfree(vq->log);
 350         vq->log = NULL;
 351         kfree(vq->heads);
 352         vq->heads = NULL;
 353 }
 354
 355 /* Helper to allocate iovec buffers for all vqs. */
 356 static long vhost_dev_alloc_iovecs(struct vhost_dev *dev)
 357 {
 358         struct vhost_virtqueue *vq;
 359         int i;
 360
 361         for (i = 0; i < dev->nvqs; ++i) {
 362                 vq = dev->vqs[i];
 363                 vq->indirect = kmalloc(sizeof *vq->indirect * UIO_MAXIOV,
 364                                        GFP_KERNEL);
 365                 vq->log = kmalloc(sizeof *vq->log * UIO_MAXIOV, GFP_KERNEL);
 366                 vq->heads = kmalloc(sizeof *vq->heads * UIO_MAXIOV, GFP_KERNEL);
 367                 if (!vq->indirect || !vq->log || !vq->heads)
 368                         goto err_nomem;
 369         }
 370         return 0;
 371
 372 err_nomem:
 373         for (; i >= 0; --i)
 374                 vhost_vq_free_iovecs(dev->vqs[i]);
 375         return -ENOMEM;
 376 }
 377
 378 static void vhost_dev_free_iovecs(struct vhost_dev *dev)
 379 {
 380         int i;
 381
 382         for (i = 0; i < dev->nvqs; ++i)
 383                 vhost_vq_free_iovecs(dev->vqs[i]);
 384 }
 385
 386 void vhost_dev_init(struct vhost_dev *dev,
 387                     struct vhost_virtqueue **vqs, int nvqs)
 388 {
 389         struct vhost_virtqueue *vq;
 390         int i;
 391
 392         dev->vqs = vqs;
 393         dev->nvqs = nvqs;
 394         mutex_init(&dev->mutex);
 395         dev->log_ctx = NULL;
 396         dev->log_file = NULL;
 397         dev->memory = NULL;
 398         dev->mm = NULL;
 399         dev->worker = NULL;
 400         init_llist_head(&dev->work_list);
 401
 402
 403         for (i = 0; i < dev->nvqs; ++i) {
 404                 vq = dev->vqs[i];
 405                 vq->log = NULL;
 406                 vq->indirect = NULL;
 407                 vq->heads = NULL;
 408                 vq->dev = dev;
 409                 mutex_init(&vq->mutex);
 410                 vhost_vq_reset(dev, vq);
 411                 if (vq->handle_kick)
 412                         vhost_poll_init(&vq->poll, vq->handle_kick,
 413                                         POLLIN, dev);
 414         }
 415 }
 416 EXPORT_SYMBOL_GPL(vhost_dev_init);
 417
 418 /* Caller should have device mutex */
 419 long vhost_dev_check_owner(struct vhost_dev *dev)
 420 {
 421         /* Are you the owner? If not, I don't think you mean to do that */
 422         return dev->mm == current->mm ? 0 : -EPERM;
 423 }
 424 EXPORT_SYMBOL_GPL(vhost_dev_check_owner);
 425
 426 struct vhost_attach_cgroups_struct {
 427         struct vhost_work work;
 428         struct task_struct *owner;
 429         int ret;
 430 };
 431
 432 static void vhost_attach_cgroups_work(struct vhost_work *work)
 433 {
 434         struct vhost_attach_cgroups_struct *s;
 435
 436         s = container_of(work, struct vhost_attach_cgroups_struct, work);
 437         s->ret = cgroup_attach_task_all(s->owner, current);
 438 }
 439
 440 static int vhost_attach_cgroups(struct vhost_dev *dev)
 441 {
 442         struct vhost_attach_cgroups_struct attach;
 443
 444         attach.owner = current;
 445         vhost_work_init(&attach.work, vhost_attach_cgroups_work);
 446         vhost_work_queue(dev, &attach.work);
 447         vhost_work_flush(dev, &attach.work);
 448         return attach.ret;
 449 }
 450
 451 /* Caller should have device mutex */
 452 bool vhost_dev_has_owner(struct vhost_dev *dev)
 453 {
 454         return dev->mm;
 455 }
 456 EXPORT_SYMBOL_GPL(vhost_dev_has_owner);
 457
 458 /* Caller should have device mutex */
 459 long vhost_dev_set_owner(struct vhost_dev *dev)
 460 {
 461         struct task_struct *worker;
 462         int err;
 463
 464         /* Is there an owner already? */
 465         if (vhost_dev_has_owner(dev)) {
 466                 err = -EBUSY;
 467                 goto err_mm;
 468         }
 469
 470         /* No owner, become one */
 471         dev->mm = get_task_mm(current);
 472         worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid);
 473         if (IS_ERR(worker)) {
 474                 err = PTR_ERR(worker);
 475                 goto err_worker;
 476         }
 477
 478         dev->worker = worker;
 479         wake_up_process(worker);        /* avoid contributing to loadavg */
 480
 481         err = vhost_attach_cgroups(dev);
 482         if (err)
 483                 goto err_cgroup;
 484
 485         err = vhost_dev_alloc_iovecs(dev);
 486         if (err)
 487                 goto err_cgroup;
 488
 489         return 0;
 490 err_cgroup:
 491         kthread_stop(worker);
 492         dev->worker = NULL;
 493 err_worker:
 494         if (dev->mm)
 495                 mmput(dev->mm);
 496         dev->mm = NULL;
 497 err_mm:
 498         return err;
 499 }
 500 EXPORT_SYMBOL_GPL(vhost_dev_set_owner);
 501
 502 struct vhost_memory *vhost_dev_reset_owner_prepare(void)
 503 {
 504         return kmalloc(offsetof(struct vhost_memory, regions), GFP_KERNEL);
 505 }
 506 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner_prepare);
 507
 508 /* Caller should have device mutex */
 509 void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_memory *memory)
 510 {
 511         int i;
 512
 513         vhost_dev_cleanup(dev, true);
 514
 515         /* Restore memory to default empty mapping. */
 516         memory->nregions = 0;
 517         dev->memory = memory;
 518         /* We don't need VQ locks below since vhost_dev_cleanup makes sure
 519          * VQs aren't running.
 520          */
 521         for (i = 0; i < dev->nvqs; ++i)
 522                 dev->vqs[i]->memory = memory;
 523 }
 524 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner);
 525
 526 void vhost_dev_stop(struct vhost_dev *dev)
 527 {
 528         int i;
 529
 530         for (i = 0; i < dev->nvqs; ++i) {
 531                 if (dev->vqs[i]->kick && dev->vqs[i]->handle_kick) {
 532                         vhost_poll_stop(&dev->vqs[i]->poll);
 533                         vhost_poll_flush(&dev->vqs[i]->poll);
 534                 }
 535         }
 536 }
 537 EXPORT_SYMBOL_GPL(vhost_dev_stop);
 538
 539 /* Caller should have device mutex if and only if locked is set */
 540 void vhost_dev_cleanup(struct vhost_dev *dev, bool locked)
 541 {
 542         int i;
 543
 544         for (i = 0; i < dev->nvqs; ++i) {
 545                 if (dev->vqs[i]->error_ctx)
 546                         eventfd_ctx_put(dev->vqs[i]->error_ctx);
 547                 if (dev->vqs[i]->error)
 548                         fput(dev->vqs[i]->error);
 549                 if (dev->vqs[i]->kick)
 550                         fput(dev->vqs[i]->kick);
 551                 if (dev->vqs[i]->call_ctx)
 552                         eventfd_ctx_put(dev->vqs[i]->call_ctx);
 553                 if (dev->vqs[i]->call)
 554                         fput(dev->vqs[i]->call);
 555                 vhost_vq_reset(dev, dev->vqs[i]);
 556         }
 557         vhost_dev_free_iovecs(dev);
 558         if (dev->log_ctx)
 559                 eventfd_ctx_put(dev->log_ctx);
 560         dev->log_ctx = NULL;
 561         if (dev->log_file)
 562                 fput(dev->log_file);
 563         dev->log_file = NULL;
 564         /* No one will access memory at this point */
 565         kvfree(dev->memory);
 566         dev->memory = NULL;
 567         WARN_ON(!llist_empty(&dev->work_list));
 568         if (dev->worker) {
 569                 kthread_stop(dev->worker);
 570                 dev->worker = NULL;
 571         }
 572         if (dev->mm)
 573                 mmput(dev->mm);
 574         dev->mm = NULL;
 575 }
 576 EXPORT_SYMBOL_GPL(vhost_dev_cleanup);
 577
 578 static int log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
 579 {
 580         u64 a = addr / VHOST_PAGE_SIZE / 8;
 581
 582         /* Make sure 64 bit math will not overflow. */
 583         if (a > ULONG_MAX - (unsigned long)log_base ||
 584             a + (unsigned long)log_base > ULONG_MAX)
 585                 return 0;
 586
 587         return access_ok(VERIFY_WRITE, log_base + a,
 588                          (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8);
 589 }
 590
 591 /* Caller should have vq mutex and device mutex. */
 592 static int vq_memory_access_ok(void __user *log_base, struct vhost_memory *mem,
 593                                int log_all)
 594 {
 595         int i;
 596
 597         if (!mem)
 598                 return 0;
 599
 600         for (i = 0; i < mem->nregions; ++i) {
 601                 struct vhost_memory_region *m = mem->regions + i;
 602                 unsigned long a = m->userspace_addr;
 603                 if (m->memory_size > ULONG_MAX)
 604                         return 0;
 605                 else if (!access_ok(VERIFY_WRITE, (void __user *)a,
 606                                     m->memory_size))
 607                         return 0;
 608                 else if (log_all && !log_access_ok(log_base,
 609                                                    m->guest_phys_addr,
 610                                                    m->memory_size))
 611                         return 0;
 612         }
 613         return 1;
 614 }
 615
 616 /* Can we switch to this memory table? */
 617 /* Caller should have device mutex but not vq mutex */
 618 static int memory_access_ok(struct vhost_dev *d, struct vhost_memory *mem,
 619                             int log_all)
 620 {
 621         int i;
 622
 623         for (i = 0; i < d->nvqs; ++i) {
 624                 int ok;
 625                 bool log;
 626
 627                 mutex_lock(&d->vqs[i]->mutex);
 628                 log = log_all || vhost_has_feature(d->vqs[i], VHOST_F_LOG_ALL);
 629                 /* If ring is inactive, will check when it's enabled. */
 630                 if (d->vqs[i]->private_data)
 631                         ok = vq_memory_access_ok(d->vqs[i]->log_base, mem, log);
 632                 else
 633                         ok = 1;
 634                 mutex_unlock(&d->vqs[i]->mutex);
 635                 if (!ok)
 636                         return 0;
 637         }
 638         return 1;
 639 }
 640
 641 static int vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
 642                         struct vring_desc __user *desc,
 643                         struct vring_avail __user *avail,
 644                         struct vring_used __user *used)
 645 {
 646         size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
 647         return access_ok(VERIFY_READ, desc, num * sizeof *desc) &&
 648                access_ok(VERIFY_READ, avail,
 649                          sizeof *avail + num * sizeof *avail->ring + s) &&
 650                access_ok(VERIFY_WRITE, used,
 651                         sizeof *used + num * sizeof *used->ring + s);
 652 }
 653
 654 /* Can we log writes? */
 655 /* Caller should have device mutex but not vq mutex */
 656 int vhost_log_access_ok(struct vhost_dev *dev)
 657 {
 658         return memory_access_ok(dev, dev->memory, 1);
 659 }
 660 EXPORT_SYMBOL_GPL(vhost_log_access_ok);
 661
 662 /* Verify access for write logging. */
 663 /* Caller should have vq mutex and device mutex */
 664 static int vq_log_access_ok(struct vhost_virtqueue *vq,
 665                             void __user *log_base)
 666 {
 667         size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
 668
 669         return vq_memory_access_ok(log_base, vq->memory,
 670                                    vhost_has_feature(vq, VHOST_F_LOG_ALL)) &&
 671                 (!vq->log_used || log_access_ok(log_base, vq->log_addr,
 672                                         sizeof *vq->used +
 673                                         vq->num * sizeof *vq->used->ring + s));
 674 }
 675
 676 /* Can we start vq? */
 677 /* Caller should have vq mutex and device mutex */
 678 int vhost_vq_access_ok(struct vhost_virtqueue *vq)
 679 {
 680         return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used) &&
 681                 vq_log_access_ok(vq, vq->log_base);
 682 }
 683 EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
 684
 685 static int vhost_memory_reg_sort_cmp(const void *p1, const void *p2)
 686 {
 687         const struct vhost_memory_region *r1 = p1, *r2 = p2;
 688         if (r1->guest_phys_addr < r2->guest_phys_addr)
 689                 return 1;
 690         if (r1->guest_phys_addr > r2->guest_phys_addr)
 691                 return -1;
 692         return 0;
 693 }
 694
 695 static void *vhost_kvzalloc(unsigned long size)
 696 {
 697         void *n = kzalloc(size, GFP_KERNEL | __GFP_NOWARN | __GFP_REPEAT);
 698
 699         if (!n)
 700                 n = vzalloc(size);
 701         return n;
 702 }
 703
 704 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
 705 {
 706         struct vhost_memory mem, *newmem, *oldmem;
 707         unsigned long size = offsetof(struct vhost_memory, regions);
 708         int i;
 709
 710         if (copy_from_user(&mem, m, size))
 711                 return -EFAULT;
 712         if (mem.padding)
 713                 return -EOPNOTSUPP;
 714         if (mem.nregions > max_mem_regions)
 715                 return -E2BIG;
 716         newmem = vhost_kvzalloc(size + mem.nregions * sizeof(*m->regions));
 717         if (!newmem)
 718                 return -ENOMEM;
 719
 720         memcpy(newmem, &mem, size);
 721         if (copy_from_user(newmem->regions, m->regions,
 722                            mem.nregions * sizeof *m->regions)) {
 723                 kvfree(newmem);
 724                 return -EFAULT;
 725         }
 726         sort(newmem->regions, newmem->nregions, sizeof(*newmem->regions),
 727                 vhost_memory_reg_sort_cmp, NULL);
 728
 729         if (!memory_access_ok(d, newmem, 0)) {
 730                 kvfree(newmem);
 731                 return -EFAULT;
 732         }
 733         oldmem = d->memory;
 734         d->memory = newmem;
 735
 736         /* All memory accesses are done under some VQ mutex. */
 737         for (i = 0; i < d->nvqs; ++i) {
 738                 mutex_lock(&d->vqs[i]->mutex);
 739                 d->vqs[i]->memory = newmem;
 740                 mutex_unlock(&d->vqs[i]->mutex);
 741         }
 742         kvfree(oldmem);
 743         return 0;
 744 }
 745
 746 long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp)
 747 {
 748         struct file *eventfp, *filep = NULL;
 749         bool pollstart = false, pollstop = false;
 750         struct eventfd_ctx *ctx = NULL;
 751         u32 __user *idxp = argp;
 752         struct vhost_virtqueue *vq;
 753         struct vhost_vring_state s;
 754         struct vhost_vring_file f;
 755         struct vhost_vring_addr a;
 756         u32 idx;
 757         long r;
 758
 759         r = get_user(idx, idxp);
 760         if (r < 0)
 761                 return r;
 762         if (idx >= d->nvqs)
 763                 return -ENOBUFS;
 764
 765         vq = d->vqs[idx];
 766
 767         mutex_lock(&vq->mutex);
 768
 769         switch (ioctl) {
 770         case VHOST_SET_VRING_NUM:
 771                 /* Resizing ring with an active backend?
 772                  * You don't want to do that. */
 773                 if (vq->private_data) {
 774                         r = -EBUSY;
 775                         break;
 776                 }
 777                 if (copy_from_user(&s, argp, sizeof s)) {
 778                         r = -EFAULT;
 779                         break;
 780                 }
 781                 if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) {
 782                         r = -EINVAL;
 783                         break;
 784                 }
 785                 vq->num = s.num;
 786                 break;
 787         case VHOST_SET_VRING_BASE:
 788                 /* Moving base with an active backend?
 789                  * You don't want to do that. */
 790                 if (vq->private_data) {
 791                         r = -EBUSY;
 792                         break;
 793                 }
 794                 if (copy_from_user(&s, argp, sizeof s)) {
 795                         r = -EFAULT;
 796                         break;
 797                 }
 798                 if (s.num > 0xffff) {
 799                         r = -EINVAL;
 800                         break;
 801                 }
 802                 vq->last_avail_idx = s.num;
 803                 /* Forget the cached index value. */
 804                 vq->avail_idx = vq->last_avail_idx;
 805                 break;
 806         case VHOST_GET_VRING_BASE:
 807                 s.index = idx;
 808                 s.num = vq->last_avail_idx;
 809                 if (copy_to_user(argp, &s, sizeof s))
 810                         r = -EFAULT;
 811                 break;
 812         case VHOST_SET_VRING_ADDR:
 813                 if (copy_from_user(&a, argp, sizeof a)) {
 814                         r = -EFAULT;
 815                         break;
 816                 }
 817                 if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) {
 818                         r = -EOPNOTSUPP;
 819                         break;
 820                 }
 821                 /* For 32bit, verify that the top 32bits of the user
 822                    data are set to zero. */
 823                 if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr ||
 824                     (u64)(unsigned long)a.used_user_addr != a.used_user_addr ||
 825                     (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) {
 826                         r = -EFAULT;
 827                         break;
 828                 }
 829
 830                 /* Make sure it's safe to cast pointers to vring types. */
 831                 BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE);
 832                 BUILD_BUG_ON(__alignof__ *vq->used > VRING_USED_ALIGN_SIZE);
 833                 if ((a.avail_user_addr & (VRING_AVAIL_ALIGN_SIZE - 1)) ||
 834                     (a.used_user_addr & (VRING_USED_ALIGN_SIZE - 1)) ||
 835                     (a.log_guest_addr & (VRING_USED_ALIGN_SIZE - 1))) {
 836                         r = -EINVAL;
 837                         break;
 838                 }
 839
 840                 /* We only verify access here if backend is configured.
 841                  * If it is not, we don't as size might not have been setup.
 842                  * We will verify when backend is configured. */
 843                 if (vq->private_data) {
 844                         if (!vq_access_ok(vq, vq->num,
 845                                 (void __user *)(unsigned long)a.desc_user_addr,
 846                                 (void __user *)(unsigned long)a.avail_user_addr,
 847                                 (void __user *)(unsigned long)a.used_user_addr)) {
 848                                 r = -EINVAL;
 849                                 break;
 850                         }
 851
 852                         /* Also validate log access for used ring if enabled. */
 853                         if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) &&
 854                             !log_access_ok(vq->log_base, a.log_guest_addr,
 855                                            sizeof *vq->used +
 856                                            vq->num * sizeof *vq->used->ring)) {
 857                                 r = -EINVAL;
 858                                 break;
 859                         }
 860                 }
 861
 862                 vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
 863                 vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
 864                 vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
 865                 vq->log_addr = a.log_guest_addr;
 866                 vq->used = (void __user *)(unsigned long)a.used_user_addr;
 867                 break;
 868         case VHOST_SET_VRING_KICK:
 869                 if (copy_from_user(&f, argp, sizeof f)) {
 870                         r = -EFAULT;
 871                         break;
 872                 }
 873                 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
 874                 if (IS_ERR(eventfp)) {
 875                         r = PTR_ERR(eventfp);
 876                         break;
 877                 }
 878                 if (eventfp != vq->kick) {
 879                         pollstop = (filep = vq->kick) != NULL;
 880                         pollstart = (vq->kick = eventfp) != NULL;
 881                 } else
 882                         filep = eventfp;
 883                 break;
 884         case VHOST_SET_VRING_CALL:
 885                 if (copy_from_user(&f, argp, sizeof f)) {
 886                         r = -EFAULT;
 887                         break;
 888                 }
 889                 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
 890                 if (IS_ERR(eventfp)) {
 891                         r = PTR_ERR(eventfp);
 892                         break;
 893                 }
 894                 if (eventfp != vq->call) {
 895                         filep = vq->call;
 896                         ctx = vq->call_ctx;
 897                         vq->call = eventfp;
 898                         vq->call_ctx = eventfp ?
 899                                 eventfd_ctx_fileget(eventfp) : NULL;
 900                 } else
 901                         filep = eventfp;
 902                 break;
 903         case VHOST_SET_VRING_ERR:
 904                 if (copy_from_user(&f, argp, sizeof f)) {
 905                         r = -EFAULT;
 906                         break;
 907                 }
 908                 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
 909                 if (IS_ERR(eventfp)) {
 910                         r = PTR_ERR(eventfp);
 911                         break;
 912                 }
 913                 if (eventfp != vq->error) {
 914                         filep = vq->error;
 915                         vq->error = eventfp;
 916                         ctx = vq->error_ctx;
 917                         vq->error_ctx = eventfp ?
 918                                 eventfd_ctx_fileget(eventfp) : NULL;
 919                 } else
 920                         filep = eventfp;
 921                 break;
 922         case VHOST_SET_VRING_ENDIAN:
 923                 r = vhost_set_vring_endian(vq, argp);
 924                 break;
 925         case VHOST_GET_VRING_ENDIAN:
 926                 r = vhost_get_vring_endian(vq, idx, argp);
 927                 break;
 928         case VHOST_SET_VRING_BUSYLOOP_TIMEOUT:
 929                 if (copy_from_user(&s, argp, sizeof(s))) {
 930                         r = -EFAULT;
 931                         break;
 932                 }
 933                 vq->busyloop_timeout = s.num;
 934                 break;
 935         case VHOST_GET_VRING_BUSYLOOP_TIMEOUT:
 936                 s.index = idx;
 937                 s.num = vq->busyloop_timeout;
 938                 if (copy_to_user(argp, &s, sizeof(s)))
 939                         r = -EFAULT;
 940                 break;
 941         default:
 942                 r = -ENOIOCTLCMD;
 943         }
 944
 945         if (pollstop && vq->handle_kick)
 946                 vhost_poll_stop(&vq->poll);
 947
 948         if (ctx)
 949                 eventfd_ctx_put(ctx);
 950         if (filep)
 951                 fput(filep);
 952
 953         if (pollstart && vq->handle_kick)
 954                 r = vhost_poll_start(&vq->poll, vq->kick);
 955
 956         mutex_unlock(&vq->mutex);
 957
 958         if (pollstop && vq->handle_kick)
 959                 vhost_poll_flush(&vq->poll);
 960         return r;
 961 }
 962 EXPORT_SYMBOL_GPL(vhost_vring_ioctl);
 963
 964 /* Caller must have device mutex */
 965 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
 966 {
 967         struct file *eventfp, *filep = NULL;
 968         struct eventfd_ctx *ctx = NULL;
 969         u64 p;
 970         long r;
 971         int i, fd;
 972
 973         /* If you are not the owner, you can become one */
 974         if (ioctl == VHOST_SET_OWNER) {
 975                 r = vhost_dev_set_owner(d);
 976                 goto done;
 977         }
 978
 979         /* You must be the owner to do anything else */
 980         r = vhost_dev_check_owner(d);
 981         if (r)
 982                 goto done;
 983
 984         switch (ioctl) {
 985         case VHOST_SET_MEM_TABLE:
 986                 r = vhost_set_memory(d, argp);
 987                 break;
 988         case VHOST_SET_LOG_BASE:
 989                 if (copy_from_user(&p, argp, sizeof p)) {
 990                         r = -EFAULT;
 991                         break;
 992                 }
 993                 if ((u64)(unsigned long)p != p) {
 994                         r = -EFAULT;
 995                         break;
 996                 }
 997                 for (i = 0; i < d->nvqs; ++i) {
 998                         struct vhost_virtqueue *vq;
 999                         void __user *base = (void __user *)(unsigned long)p;
1000                         vq = d->vqs[i];
1001                         mutex_lock(&vq->mutex);
1002                         /* If ring is inactive, will check when it's enabled. */
1003                         if (vq->private_data && !vq_log_access_ok(vq, base))
1004                                 r = -EFAULT;
1005                         else
1006                                 vq->log_base = base;
1007                         mutex_unlock(&vq->mutex);
1008                 }
1009                 break;
1010         case VHOST_SET_LOG_FD:
1011                 r = get_user(fd, (int __user *)argp);
1012                 if (r < 0)
1013                         break;
1014                 eventfp = fd == -1 ? NULL : eventfd_fget(fd);
1015                 if (IS_ERR(eventfp)) {
1016                         r = PTR_ERR(eventfp);
1017                         break;
1018                 }
1019                 if (eventfp != d->log_file) {
1020                         filep = d->log_file;
1021                         d->log_file = eventfp;
1022                         ctx = d->log_ctx;
1023                         d->log_ctx = eventfp ?
1024                                 eventfd_ctx_fileget(eventfp) : NULL;
1025                 } else
1026                         filep = eventfp;
1027                 for (i = 0; i < d->nvqs; ++i) {
1028                         mutex_lock(&d->vqs[i]->mutex);
1029                         d->vqs[i]->log_ctx = d->log_ctx;
1030                         mutex_unlock(&d->vqs[i]->mutex);
1031                 }
1032                 if (ctx)
1033                         eventfd_ctx_put(ctx);
1034                 if (filep)
1035                         fput(filep);
1036                 break;
1037         default:
1038                 r = -ENOIOCTLCMD;
1039                 break;
1040         }
1041 done:
1042         return r;
1043 }
1044 EXPORT_SYMBOL_GPL(vhost_dev_ioctl);
1045
1046 static const struct vhost_memory_region *find_region(struct vhost_memory *mem,
1047                                                      __u64 addr, __u32 len)
1048 {
1049         const struct vhost_memory_region *reg;
1050         int start = 0, end = mem->nregions;
1051
1052         while (start < end) {
1053                 int slot = start + (end - start) / 2;
1054                 reg = mem->regions + slot;
1055                 if (addr >= reg->guest_phys_addr)
1056                         end = slot;
1057                 else
1058                         start = slot + 1;
1059         }
1060
1061         reg = mem->regions + start;
1062         if (addr >= reg->guest_phys_addr &&
1063                 reg->guest_phys_addr + reg->memory_size > addr)
1064                 return reg;
1065         return NULL;
1066 }
1067
1068 /* TODO: This is really inefficient.  We need something like get_user()
1069  * (instruction directly accesses the data, with an exception table entry
1070  * returning -EFAULT). See Documentation/x86/exception-tables.txt.
1071  */
1072 static int set_bit_to_user(int nr, void __user *addr)
1073 {
1074         unsigned long log = (unsigned long)addr;
1075         struct page *page;
1076         void *base;
1077         int bit = nr + (log % PAGE_SIZE) * 8;
1078         int r;
1079
1080         r = get_user_pages_fast(log, 1, 1, &page);
1081         if (r < 0)
1082                 return r;
1083         BUG_ON(r != 1);
1084         base = kmap_atomic(page);
1085         set_bit(bit, base);
1086         kunmap_atomic(base);
1087         set_page_dirty_lock(page);
1088         put_page(page);
1089         return 0;
1090 }
1091
1092 static int log_write(void __user *log_base,
1093                      u64 write_address, u64 write_length)
1094 {
1095         u64 write_page = write_address / VHOST_PAGE_SIZE;
1096         int r;
1097
1098         if (!write_length)
1099                 return 0;
1100         write_length += write_address % VHOST_PAGE_SIZE;
1101         for (;;) {
1102                 u64 base = (u64)(unsigned long)log_base;
1103                 u64 log = base + write_page / 8;
1104                 int bit = write_page % 8;
1105                 if ((u64)(unsigned long)log != log)
1106                         return -EFAULT;
1107                 r = set_bit_to_user(bit, (void __user *)(unsigned long)log);
1108                 if (r < 0)
1109                         return r;
1110                 if (write_length <= VHOST_PAGE_SIZE)
1111                         break;
1112                 write_length -= VHOST_PAGE_SIZE;
1113                 write_page += 1;
1114         }
1115         return r;
1116 }
1117
1118 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
1119                     unsigned int log_num, u64 len)
1120 {
1121         int i, r;
1122
1123         /* Make sure data written is seen before log. */
1124         smp_wmb();
1125         for (i = 0; i < log_num; ++i) {
1126                 u64 l = min(log[i].len, len);
1127                 r = log_write(vq->log_base, log[i].addr, l);
1128                 if (r < 0)
1129                         return r;
1130                 len -= l;
1131                 if (!len) {
1132                         if (vq->log_ctx)
1133                                 eventfd_signal(vq->log_ctx, 1);
1134                         return 0;
1135                 }
1136         }
1137         /* Length written exceeds what we have stored. This is a bug. */
1138         BUG();
1139         return 0;
1140 }
1141 EXPORT_SYMBOL_GPL(vhost_log_write);
1142
1143 static int vhost_update_used_flags(struct vhost_virtqueue *vq)
1144 {
1145         void __user *used;
1146         if (__put_user(cpu_to_vhost16(vq, vq->used_flags), &vq->used->flags) < 0)
1147                 return -EFAULT;
1148         if (unlikely(vq->log_used)) {
1149                 /* Make sure the flag is seen before log. */
1150                 smp_wmb();
1151                 /* Log used flag write. */
1152                 used = &vq->used->flags;
1153                 log_write(vq->log_base, vq->log_addr +
1154                           (used - (void __user *)vq->used),
1155                           sizeof vq->used->flags);
1156                 if (vq->log_ctx)
1157                         eventfd_signal(vq->log_ctx, 1);
1158         }
1159         return 0;
1160 }
1161
1162 static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event)
1163 {
1164         if (__put_user(cpu_to_vhost16(vq, vq->avail_idx), vhost_avail_event(vq)))
1165                 return -EFAULT;
1166         if (unlikely(vq->log_used)) {
1167                 void __user *used;
1168                 /* Make sure the event is seen before log. */
1169                 smp_wmb();
1170                 /* Log avail event write */
1171                 used = vhost_avail_event(vq);
1172                 log_write(vq->log_base, vq->log_addr +
1173                           (used - (void __user *)vq->used),
1174                           sizeof *vhost_avail_event(vq));
1175                 if (vq->log_ctx)
1176                         eventfd_signal(vq->log_ctx, 1);
1177         }
1178         return 0;
1179 }
1180
1181 int vhost_vq_init_access(struct vhost_virtqueue *vq)
1182 {
1183         __virtio16 last_used_idx;
1184         int r;
1185         bool is_le = vq->is_le;
1186
1187         if (!vq->private_data) {
1188                 vhost_reset_is_le(vq);
1189                 return 0;
1190         }
1191
1192         vhost_init_is_le(vq);
1193
1194         r = vhost_update_used_flags(vq);
1195         if (r)
1196                 goto err;
1197         vq->signalled_used_valid = false;
1198         if (!access_ok(VERIFY_READ, &vq->used->idx, sizeof vq->used->idx)) {
1199                 r = -EFAULT;
1200                 goto err;
1201         }
1202         r = __get_user(last_used_idx, &vq->used->idx);
1203         if (r)
1204                 goto err;
1205         vq->last_used_idx = vhost16_to_cpu(vq, last_used_idx);
1206         return 0;
1207 err:
1208         vq->is_le = is_le;
1209         return r;
1210 }
1211 EXPORT_SYMBOL_GPL(vhost_vq_init_access);
1212
1213 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
1214                           struct iovec iov[], int iov_size)
1215 {
1216         const struct vhost_memory_region *reg;
1217         struct vhost_memory *mem;
1218         struct iovec *_iov;
1219         u64 s = 0;
1220         int ret = 0;
1221
1222         mem = vq->memory;
1223         while ((u64)len > s) {
1224                 u64 size;
1225                 if (unlikely(ret >= iov_size)) {
1226                         ret = -ENOBUFS;
1227                         break;
1228                 }
1229                 reg = find_region(mem, addr, len);
1230                 if (unlikely(!reg)) {
1231                         ret = -EFAULT;
1232                         break;
1233                 }
1234                 _iov = iov + ret;
1235                 size = reg->memory_size - addr + reg->guest_phys_addr;
1236                 _iov->iov_len = min((u64)len - s, size);
1237                 _iov->iov_base = (void __user *)(unsigned long)
1238                         (reg->userspace_addr + addr - reg->guest_phys_addr);
1239                 s += size;
1240                 addr += size;
1241                 ++ret;
1242         }
1243
1244         return ret;
1245 }
1246
1247 /* Each buffer in the virtqueues is actually a chain of descriptors.  This
1248  * function returns the next descriptor in the chain,
1249  * or -1U if we're at the end. */
1250 static unsigned next_desc(struct vhost_virtqueue *vq, struct vring_desc *desc)
1251 {
1252         unsigned int next;
1253
1254         /* If this descriptor says it doesn't chain, we're done. */
1255         if (!(desc->flags & cpu_to_vhost16(vq, VRING_DESC_F_NEXT)))
1256                 return -1U;
1257
1258         /* Check they're not leading us off end of descriptors. */
1259         next = vhost16_to_cpu(vq, desc->next);
1260         /* Make sure compiler knows to grab that: we don't want it changing! */
1261         /* We will use the result as an index in an array, so most
1262          * architectures only need a compiler barrier here. */
1263         read_barrier_depends();
1264
1265         return next;
1266 }
1267
1268 static int get_indirect(struct vhost_virtqueue *vq,
1269                         struct iovec iov[], unsigned int iov_size,
1270                         unsigned int *out_num, unsigned int *in_num,
1271                         struct vhost_log *log, unsigned int *log_num,
1272                         struct vring_desc *indirect)
1273 {
1274         struct vring_desc desc;
1275         unsigned int i = 0, count, found = 0;
1276         u32 len = vhost32_to_cpu(vq, indirect->len);
1277         struct iov_iter from;
1278         int ret;
1279
1280         /* Sanity check */
1281         if (unlikely(len % sizeof desc)) {
1282                 vq_err(vq, "Invalid length in indirect descriptor: "
1283                        "len 0x%llx not multiple of 0x%zx\n",
1284                        (unsigned long long)len,
1285                        sizeof desc);
1286                 return -EINVAL;
1287         }
1288
1289         ret = translate_desc(vq, vhost64_to_cpu(vq, indirect->addr), len, vq->indirect,
1290                              UIO_MAXIOV);
1291         if (unlikely(ret < 0)) {
1292                 vq_err(vq, "Translation failure %d in indirect.\n", ret);
1293                 return ret;
1294         }
1295         iov_iter_init(&from, READ, vq->indirect, ret, len);
1296
1297         /* We will use the result as an address to read from, so most
1298          * architectures only need a compiler barrier here. */
1299         read_barrier_depends();
1300
1301         count = len / sizeof desc;
1302         /* Buffers are chained via a 16 bit next field, so
1303          * we can have at most 2^16 of these. */
1304         if (unlikely(count > USHRT_MAX + 1)) {
1305                 vq_err(vq, "Indirect buffer length too big: %d\n",
1306                        indirect->len);
1307                 return -E2BIG;
1308         }
1309
1310         do {
1311                 unsigned iov_count = *in_num + *out_num;
1312                 if (unlikely(++found > count)) {
1313                         vq_err(vq, "Loop detected: last one at %u "
1314                                "indirect size %u\n",
1315                                i, count);
1316                         return -EINVAL;
1317                 }
1318                 if (unlikely(copy_from_iter(&desc, sizeof(desc), &from) !=
1319                              sizeof(desc))) {
1320                         vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n",
1321                                i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
1322                         return -EINVAL;
1323                 }
1324                 if (unlikely(desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT))) {
1325                         vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n",
1326                                i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
1327                         return -EINVAL;
1328                 }
1329
1330                 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
1331                                      vhost32_to_cpu(vq, desc.len), iov + iov_count,
1332                                      iov_size - iov_count);
1333                 if (unlikely(ret < 0)) {
1334                         vq_err(vq, "Translation failure %d indirect idx %d\n",
1335                                ret, i);
1336                         return ret;
1337                 }
1338                 /* If this is an input descriptor, increment that count. */
1339                 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE)) {
1340                         *in_num += ret;
1341                         if (unlikely(log)) {
1342                                 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
1343                                 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
1344                                 ++*log_num;
1345                         }
1346                 } else {
1347                         /* If it's an output descriptor, they're all supposed
1348                          * to come before any input descriptors. */
1349                         if (unlikely(*in_num)) {
1350                                 vq_err(vq, "Indirect descriptor "
1351                                        "has out after in: idx %d\n", i);
1352                                 return -EINVAL;
1353                         }
1354                         *out_num += ret;
1355                 }
1356         } while ((i = next_desc(vq, &desc)) != -1);
1357         return 0;
1358 }
1359
1360 /* This looks in the virtqueue and for the first available buffer, and converts
1361  * it to an iovec for convenient access.  Since descriptors consist of some
1362  * number of output then some number of input descriptors, it's actually two
1363  * iovecs, but we pack them into one and note how many of each there were.
1364  *
1365  * This function returns the descriptor number found, or vq->num (which is
1366  * never a valid descriptor number) if none was found.  A negative code is
1367  * returned on error. */
1368 int vhost_get_vq_desc(struct vhost_virtqueue *vq,
1369                       struct iovec iov[], unsigned int iov_size,
1370                       unsigned int *out_num, unsigned int *in_num,
1371                       struct vhost_log *log, unsigned int *log_num)
1372 {
1373         struct vring_desc desc;
1374         unsigned int i, head, found = 0;
1375         u16 last_avail_idx;
1376         __virtio16 avail_idx;
1377         __virtio16 ring_head;
1378         int ret;
1379
1380         /* Check it isn't doing very strange things with descriptor numbers. */
1381         last_avail_idx = vq->last_avail_idx;
1382         if (unlikely(__get_user(avail_idx, &vq->avail->idx))) {
1383                 vq_err(vq, "Failed to access avail idx at %p\n",
1384                        &vq->avail->idx);
1385                 return -EFAULT;
1386         }
1387         vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
1388
1389         if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
1390                 vq_err(vq, "Guest moved used index from %u to %u",
1391                        last_avail_idx, vq->avail_idx);
1392                 return -EFAULT;
1393         }
1394
1395         /* If there's nothing new since last we looked, return invalid. */
1396         if (vq->avail_idx == last_avail_idx)
1397                 return vq->num;
1398
1399         /* Only get avail ring entries after they have been exposed by guest. */
1400         smp_rmb();
1401
1402         /* Grab the next descriptor number they're advertising, and increment
1403          * the index we've seen. */
1404         if (unlikely(__get_user(ring_head,
1405                                 &vq->avail->ring[last_avail_idx & (vq->num - 1)]))) {
1406                 vq_err(vq, "Failed to read head: idx %d address %p\n",
1407                        last_avail_idx,
1408                        &vq->avail->ring[last_avail_idx % vq->num]);
1409                 return -EFAULT;
1410         }
1411
1412         head = vhost16_to_cpu(vq, ring_head);
1413
1414         /* If their number is silly, that's an error. */
1415         if (unlikely(head >= vq->num)) {
1416                 vq_err(vq, "Guest says index %u > %u is available",
1417                        head, vq->num);
1418                 return -EINVAL;
1419         }
1420
1421         /* When we start there are none of either input nor output. */
1422         *out_num = *in_num = 0;
1423         if (unlikely(log))
1424                 *log_num = 0;
1425
1426         i = head;
1427         do {
1428                 unsigned iov_count = *in_num + *out_num;
1429                 if (unlikely(i >= vq->num)) {
1430                         vq_err(vq, "Desc index is %u > %u, head = %u",
1431                                i, vq->num, head);
1432                         return -EINVAL;
1433                 }
1434                 if (unlikely(++found > vq->num)) {
1435                         vq_err(vq, "Loop detected: last one at %u "
1436                                "vq size %u head %u\n",
1437                                i, vq->num, head);
1438                         return -EINVAL;
1439                 }
1440                 ret = __copy_from_user(&desc, vq->desc + i, sizeof desc);
1441                 if (unlikely(ret)) {
1442                         vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
1443                                i, vq->desc + i);
1444                         return -EFAULT;
1445                 }
1446                 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT)) {
1447                         ret = get_indirect(vq, iov, iov_size,
1448                                            out_num, in_num,
1449                                            log, log_num, &desc);
1450                         if (unlikely(ret < 0)) {
1451                                 vq_err(vq, "Failure detected "
1452                                        "in indirect descriptor at idx %d\n", i);
1453                                 return ret;
1454                         }
1455                         continue;
1456                 }
1457
1458                 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
1459                                      vhost32_to_cpu(vq, desc.len), iov + iov_count,
1460                                      iov_size - iov_count);
1461                 if (unlikely(ret < 0)) {
1462                         vq_err(vq, "Translation failure %d descriptor idx %d\n",
1463                                ret, i);
1464                         return ret;
1465                 }
1466                 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE)) {
1467                         /* If this is an input descriptor,
1468                          * increment that count. */
1469                         *in_num += ret;
1470                         if (unlikely(log)) {
1471                                 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
1472                                 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
1473                                 ++*log_num;
1474                         }
1475                 } else {
1476                         /* If it's an output descriptor, they're all supposed
1477                          * to come before any input descriptors. */
1478                         if (unlikely(*in_num)) {
1479                                 vq_err(vq, "Descriptor has out after in: "
1480                                        "idx %d\n", i);
1481                                 return -EINVAL;
1482                         }
1483                         *out_num += ret;
1484                 }
1485         } while ((i = next_desc(vq, &desc)) != -1);
1486
1487         /* On success, increment avail index. */
1488         vq->last_avail_idx++;
1489
1490         /* Assume notifications from guest are disabled at this point,
1491          * if they aren't we would need to update avail_event index. */
1492         BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
1493         return head;
1494 }
1495 EXPORT_SYMBOL_GPL(vhost_get_vq_desc);
1496
1497 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
1498 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
1499 {
1500         vq->last_avail_idx -= n;
1501 }
1502 EXPORT_SYMBOL_GPL(vhost_discard_vq_desc);
1503
1504 /* After we've used one of their buffers, we tell them about it.  We'll then
1505  * want to notify the guest, using eventfd. */
1506 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
1507 {
1508         struct vring_used_elem heads = {
1509                 cpu_to_vhost32(vq, head),
1510                 cpu_to_vhost32(vq, len)
1511         };
1512
1513         return vhost_add_used_n(vq, &heads, 1);
1514 }
1515 EXPORT_SYMBOL_GPL(vhost_add_used);
1516
1517 static int __vhost_add_used_n(struct vhost_virtqueue *vq,
1518                             struct vring_used_elem *heads,
1519                             unsigned count)
1520 {
1521         struct vring_used_elem __user *used;
1522         u16 old, new;
1523         int start;
1524
1525         start = vq->last_used_idx & (vq->num - 1);
1526         used = vq->used->ring + start;
1527         if (count == 1) {
1528                 if (__put_user(heads[0].id, &used->id)) {
1529                         vq_err(vq, "Failed to write used id");
1530                         return -EFAULT;
1531                 }
1532                 if (__put_user(heads[0].len, &used->len)) {
1533                         vq_err(vq, "Failed to write used len");
1534                         return -EFAULT;
1535                 }
1536         } else if (__copy_to_user(used, heads, count * sizeof *used)) {
1537                 vq_err(vq, "Failed to write used");
1538                 return -EFAULT;
1539         }
1540         if (unlikely(vq->log_used)) {
1541                 /* Make sure data is seen before log. */
1542                 smp_wmb();
1543                 /* Log used ring entry write. */
1544                 log_write(vq->log_base,
1545                           vq->log_addr +
1546                            ((void __user *)used - (void __user *)vq->used),
1547                           count * sizeof *used);
1548         }
1549         old = vq->last_used_idx;
1550         new = (vq->last_used_idx += count);
1551         /* If the driver never bothers to signal in a very long while,
1552          * used index might wrap around. If that happens, invalidate
1553          * signalled_used index we stored. TODO: make sure driver
1554          * signals at least once in 2^16 and remove this. */
1555         if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old)))
1556                 vq->signalled_used_valid = false;
1557         return 0;
1558 }
1559
1560 /* After we've used one of their buffers, we tell them about it.  We'll then
1561  * want to notify the guest, using eventfd. */
1562 int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
1563                      unsigned count)
1564 {
1565         int start, n, r;
1566
1567         start = vq->last_used_idx & (vq->num - 1);
1568         n = vq->num - start;
1569         if (n < count) {
1570                 r = __vhost_add_used_n(vq, heads, n);
1571                 if (r < 0)
1572                         return r;
1573                 heads += n;
1574                 count -= n;
1575         }
1576         r = __vhost_add_used_n(vq, heads, count);
1577
1578         /* Make sure buffer is written before we update index. */
1579         smp_wmb();
1580         if (__put_user(cpu_to_vhost16(vq, vq->last_used_idx), &vq->used->idx)) {
1581                 vq_err(vq, "Failed to increment used idx");
1582                 return -EFAULT;
1583         }
1584         if (unlikely(vq->log_used)) {
1585                 /* Log used index update. */
1586                 log_write(vq->log_base,
1587                           vq->log_addr + offsetof(struct vring_used, idx),
1588                           sizeof vq->used->idx);
1589                 if (vq->log_ctx)
1590                         eventfd_signal(vq->log_ctx, 1);
1591         }
1592         return r;
1593 }
1594 EXPORT_SYMBOL_GPL(vhost_add_used_n);
1595
1596 static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1597 {
1598         __u16 old, new;
1599         __virtio16 event;
1600         bool v;
1601         /* Flush out used index updates. This is paired
1602          * with the barrier that the Guest executes when enabling
1603          * interrupts. */
1604         smp_mb();
1605
1606         if (vhost_has_feature(vq, VIRTIO_F_NOTIFY_ON_EMPTY) &&
1607             unlikely(vq->avail_idx == vq->last_avail_idx))
1608                 return true;
1609
1610         if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
1611                 __virtio16 flags;
1612                 if (__get_user(flags, &vq->avail->flags)) {
1613                         vq_err(vq, "Failed to get flags");
1614                         return true;
1615                 }
1616                 return !(flags & cpu_to_vhost16(vq, VRING_AVAIL_F_NO_INTERRUPT));
1617         }
1618         old = vq->signalled_used;
1619         v = vq->signalled_used_valid;
1620         new = vq->signalled_used = vq->last_used_idx;
1621         vq->signalled_used_valid = true;
1622
1623         if (unlikely(!v))
1624                 return true;
1625
1626         if (__get_user(event, vhost_used_event(vq))) {
1627                 vq_err(vq, "Failed to get used event idx");
1628                 return true;
1629         }
1630         return vring_need_event(vhost16_to_cpu(vq, event), new, old);
1631 }
1632
1633 /* This actually signals the guest, using eventfd. */
1634 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1635 {
1636         /* Signal the Guest tell them we used something up. */
1637         if (vq->call_ctx && vhost_notify(dev, vq))
1638                 eventfd_signal(vq->call_ctx, 1);
1639 }
1640 EXPORT_SYMBOL_GPL(vhost_signal);
1641
1642 /* And here's the combo meal deal.  Supersize me! */
1643 void vhost_add_used_and_signal(struct vhost_dev *dev,
1644                                struct vhost_virtqueue *vq,
1645                                unsigned int head, int len)
1646 {
1647         vhost_add_used(vq, head, len);
1648         vhost_signal(dev, vq);
1649 }
1650 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal);
1651
1652 /* multi-buffer version of vhost_add_used_and_signal */
1653 void vhost_add_used_and_signal_n(struct vhost_dev *dev,
1654                                  struct vhost_virtqueue *vq,
1655                                  struct vring_used_elem *heads, unsigned count)
1656 {
1657         vhost_add_used_n(vq, heads, count);
1658         vhost_signal(dev, vq);
1659 }
1660 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n);
1661
1662 /* return true if we're sure that avaiable ring is empty */
1663 bool vhost_vq_avail_empty(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1664 {
1665         __virtio16 avail_idx;
1666         int r;
1667
1668         r = __get_user(avail_idx, &vq->avail->idx);
1669         if (r)
1670                 return false;
1671
1672         return vhost16_to_cpu(vq, avail_idx) == vq->avail_idx;
1673 }
1674 EXPORT_SYMBOL_GPL(vhost_vq_avail_empty);
1675
1676 /* OK, now we need to know about added descriptors. */
1677 bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1678 {
1679         __virtio16 avail_idx;
1680         int r;
1681
1682         if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
1683                 return false;
1684         vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
1685         if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
1686                 r = vhost_update_used_flags(vq);
1687                 if (r) {
1688                         vq_err(vq, "Failed to enable notification at %p: %d\n",
1689                                &vq->used->flags, r);
1690                         return false;
1691                 }
1692         } else {
1693                 r = vhost_update_avail_event(vq, vq->avail_idx);
1694                 if (r) {
1695                         vq_err(vq, "Failed to update avail event index at %p: %d\n",
1696                                vhost_avail_event(vq), r);
1697                         return false;
1698                 }
1699         }
1700         /* They could have slipped one in as we were doing that: make
1701          * sure it's written, then check again. */
1702         smp_mb();
1703         r = __get_user(avail_idx, &vq->avail->idx);
1704         if (r) {
1705                 vq_err(vq, "Failed to check avail idx at %p: %d\n",
1706                        &vq->avail->idx, r);
1707                 return false;
1708         }
1709
1710         return vhost16_to_cpu(vq, avail_idx) != vq->avail_idx;
1711 }
1712 EXPORT_SYMBOL_GPL(vhost_enable_notify);
1713
1714 /* We don't need to be notified again. */
1715 void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1716 {
1717         int r;
1718
1719         if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
1720                 return;
1721         vq->used_flags |= VRING_USED_F_NO_NOTIFY;
1722         if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
1723                 r = vhost_update_used_flags(vq);
1724                 if (r)
1725                         vq_err(vq, "Failed to enable notification at %p: %d\n",
1726                                &vq->used->flags, r);
1727         }
1728 }
1729 EXPORT_SYMBOL_GPL(vhost_disable_notify);
1730
1731 static int __init vhost_init(void)
1732 {
1733         return 0;
1734 }
1735
1736 static void __exit vhost_exit(void)
1737 {
1738 }
1739
1740 module_init(vhost_init);
1741 module_exit(vhost_exit);
1742
1743 MODULE_VERSION("0.0.1");
1744 MODULE_LICENSE("GPL v2");
1745 MODULE_AUTHOR("Michael S. Tsirkin");
1746 MODULE_DESCRIPTION("Host kernel accelerator for virtio");