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/kthread.h> 26 #include <linux/cgroup.h> 27 #include <linux/module.h> 28 29 #include "vhost.h" 30 31 enum { 32 VHOST_MEMORY_MAX_NREGIONS = 64, 33 VHOST_MEMORY_F_LOG = 0x1, 34 }; 35 36 #define vhost_used_event(vq) ((__virtio16 __user *)&vq->avail->ring[vq->num]) 37 #define vhost_avail_event(vq) ((__virtio16 __user *)&vq->used->ring[vq->num]) 38 39 #ifdef CONFIG_VHOST_CROSS_ENDIAN_LEGACY 40 static void vhost_vq_reset_user_be(struct vhost_virtqueue *vq) 41 { 42 vq->user_be = !virtio_legacy_is_little_endian(); 43 } 44 45 static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp) 46 { 47 struct vhost_vring_state s; 48 49 if (vq->private_data) 50 return -EBUSY; 51 52 if (copy_from_user(&s, argp, sizeof(s))) 53 return -EFAULT; 54 55 if (s.num != VHOST_VRING_LITTLE_ENDIAN && 56 s.num != VHOST_VRING_BIG_ENDIAN) 57 return -EINVAL; 58 59 vq->user_be = s.num; 60 61 return 0; 62 } 63 64 static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx, 65 int __user *argp) 66 { 67 struct vhost_vring_state s = { 68 .index = idx, 69 .num = vq->user_be 70 }; 71 72 if (copy_to_user(argp, &s, sizeof(s))) 73 return -EFAULT; 74 75 return 0; 76 } 77 78 static void vhost_init_is_le(struct vhost_virtqueue *vq) 79 { 80 /* Note for legacy virtio: user_be is initialized at reset time 81 * according to the host endianness. If userspace does not set an 82 * explicit endianness, the default behavior is native endian, as 83 * expected by legacy virtio. 84 */ 85 vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1) || !vq->user_be; 86 } 87 #else 88 static void vhost_vq_reset_user_be(struct vhost_virtqueue *vq) 89 { 90 } 91 92 static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp) 93 { 94 return -ENOIOCTLCMD; 95 } 96 97 static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx, 98 int __user *argp) 99 { 100 return -ENOIOCTLCMD; 101 } 102 103 static void vhost_init_is_le(struct vhost_virtqueue *vq) 104 { 105 if (vhost_has_feature(vq, VIRTIO_F_VERSION_1)) 106 vq->is_le = true; 107 } 108 #endif /* CONFIG_VHOST_CROSS_ENDIAN_LEGACY */ 109 110 static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh, 111 poll_table *pt) 112 { 113 struct vhost_poll *poll; 114 115 poll = container_of(pt, struct vhost_poll, table); 116 poll->wqh = wqh; 117 add_wait_queue(wqh, &poll->wait); 118 } 119 120 static int vhost_poll_wakeup(wait_queue_t *wait, unsigned mode, int sync, 121 void *key) 122 { 123 struct vhost_poll *poll = container_of(wait, struct vhost_poll, wait); 124 125 if (!((unsigned long)key & poll->mask)) 126 return 0; 127 128 vhost_poll_queue(poll); 129 return 0; 130 } 131 132 void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn) 133 { 134 INIT_LIST_HEAD(&work->node); 135 work->fn = fn; 136 init_waitqueue_head(&work->done); 137 work->flushing = 0; 138 work->queue_seq = work->done_seq = 0; 139 } 140 EXPORT_SYMBOL_GPL(vhost_work_init); 141 142 /* Init poll structure */ 143 void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn, 144 unsigned long mask, struct vhost_dev *dev) 145 { 146 init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup); 147 init_poll_funcptr(&poll->table, vhost_poll_func); 148 poll->mask = mask; 149 poll->dev = dev; 150 poll->wqh = NULL; 151 152 vhost_work_init(&poll->work, fn); 153 } 154 EXPORT_SYMBOL_GPL(vhost_poll_init); 155 156 /* Start polling a file. We add ourselves to file's wait queue. The caller must 157 * keep a reference to a file until after vhost_poll_stop is called. */ 158 int vhost_poll_start(struct vhost_poll *poll, struct file *file) 159 { 160 unsigned long mask; 161 int ret = 0; 162 163 if (poll->wqh) 164 return 0; 165 166 mask = file->f_op->poll(file, &poll->table); 167 if (mask) 168 vhost_poll_wakeup(&poll->wait, 0, 0, (void *)mask); 169 if (mask & POLLERR) { 170 if (poll->wqh) 171 remove_wait_queue(poll->wqh, &poll->wait); 172 ret = -EINVAL; 173 } 174 175 return ret; 176 } 177 EXPORT_SYMBOL_GPL(vhost_poll_start); 178 179 /* Stop polling a file. After this function returns, it becomes safe to drop the 180 * file reference. You must also flush afterwards. */ 181 void vhost_poll_stop(struct vhost_poll *poll) 182 { 183 if (poll->wqh) { 184 remove_wait_queue(poll->wqh, &poll->wait); 185 poll->wqh = NULL; 186 } 187 } 188 EXPORT_SYMBOL_GPL(vhost_poll_stop); 189 190 static bool vhost_work_seq_done(struct vhost_dev *dev, struct vhost_work *work, 191 unsigned seq) 192 { 193 int left; 194 195 spin_lock_irq(&dev->work_lock); 196 left = seq - work->done_seq; 197 spin_unlock_irq(&dev->work_lock); 198 return left <= 0; 199 } 200 201 void vhost_work_flush(struct vhost_dev *dev, struct vhost_work *work) 202 { 203 unsigned seq; 204 int flushing; 205 206 spin_lock_irq(&dev->work_lock); 207 seq = work->queue_seq; 208 work->flushing++; 209 spin_unlock_irq(&dev->work_lock); 210 wait_event(work->done, vhost_work_seq_done(dev, work, seq)); 211 spin_lock_irq(&dev->work_lock); 212 flushing = --work->flushing; 213 spin_unlock_irq(&dev->work_lock); 214 BUG_ON(flushing < 0); 215 } 216 EXPORT_SYMBOL_GPL(vhost_work_flush); 217 218 /* Flush any work that has been scheduled. When calling this, don't hold any 219 * locks that are also used by the callback. */ 220 void vhost_poll_flush(struct vhost_poll *poll) 221 { 222 vhost_work_flush(poll->dev, &poll->work); 223 } 224 EXPORT_SYMBOL_GPL(vhost_poll_flush); 225 226 void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work) 227 { 228 unsigned long flags; 229 230 spin_lock_irqsave(&dev->work_lock, flags); 231 if (list_empty(&work->node)) { 232 list_add_tail(&work->node, &dev->work_list); 233 work->queue_seq++; 234 spin_unlock_irqrestore(&dev->work_lock, flags); 235 wake_up_process(dev->worker); 236 } else { 237 spin_unlock_irqrestore(&dev->work_lock, flags); 238 } 239 } 240 EXPORT_SYMBOL_GPL(vhost_work_queue); 241 242 void vhost_poll_queue(struct vhost_poll *poll) 243 { 244 vhost_work_queue(poll->dev, &poll->work); 245 } 246 EXPORT_SYMBOL_GPL(vhost_poll_queue); 247 248 static void vhost_vq_reset(struct vhost_dev *dev, 249 struct vhost_virtqueue *vq) 250 { 251 vq->num = 1; 252 vq->desc = NULL; 253 vq->avail = NULL; 254 vq->used = NULL; 255 vq->last_avail_idx = 0; 256 vq->avail_idx = 0; 257 vq->last_used_idx = 0; 258 vq->signalled_used = 0; 259 vq->signalled_used_valid = false; 260 vq->used_flags = 0; 261 vq->log_used = false; 262 vq->log_addr = -1ull; 263 vq->private_data = NULL; 264 vq->acked_features = 0; 265 vq->log_base = NULL; 266 vq->error_ctx = NULL; 267 vq->error = NULL; 268 vq->kick = NULL; 269 vq->call_ctx = NULL; 270 vq->call = NULL; 271 vq->log_ctx = NULL; 272 vq->memory = NULL; 273 vq->is_le = virtio_legacy_is_little_endian(); 274 vhost_vq_reset_user_be(vq); 275 } 276 277 static int vhost_worker(void *data) 278 { 279 struct vhost_dev *dev = data; 280 struct vhost_work *work = NULL; 281 unsigned uninitialized_var(seq); 282 mm_segment_t oldfs = get_fs(); 283 284 set_fs(USER_DS); 285 use_mm(dev->mm); 286 287 for (;;) { 288 /* mb paired w/ kthread_stop */ 289 set_current_state(TASK_INTERRUPTIBLE); 290 291 spin_lock_irq(&dev->work_lock); 292 if (work) { 293 work->done_seq = seq; 294 if (work->flushing) 295 wake_up_all(&work->done); 296 } 297 298 if (kthread_should_stop()) { 299 spin_unlock_irq(&dev->work_lock); 300 __set_current_state(TASK_RUNNING); 301 break; 302 } 303 if (!list_empty(&dev->work_list)) { 304 work = list_first_entry(&dev->work_list, 305 struct vhost_work, node); 306 list_del_init(&work->node); 307 seq = work->queue_seq; 308 } else 309 work = NULL; 310 spin_unlock_irq(&dev->work_lock); 311 312 if (work) { 313 __set_current_state(TASK_RUNNING); 314 work->fn(work); 315 if (need_resched()) 316 schedule(); 317 } else 318 schedule(); 319 320 } 321 unuse_mm(dev->mm); 322 set_fs(oldfs); 323 return 0; 324 } 325 326 static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq) 327 { 328 kfree(vq->indirect); 329 vq->indirect = NULL; 330 kfree(vq->log); 331 vq->log = NULL; 332 kfree(vq->heads); 333 vq->heads = NULL; 334 } 335 336 /* Helper to allocate iovec buffers for all vqs. */ 337 static long vhost_dev_alloc_iovecs(struct vhost_dev *dev) 338 { 339 struct vhost_virtqueue *vq; 340 int i; 341 342 for (i = 0; i < dev->nvqs; ++i) { 343 vq = dev->vqs[i]; 344 vq->indirect = kmalloc(sizeof *vq->indirect * UIO_MAXIOV, 345 GFP_KERNEL); 346 vq->log = kmalloc(sizeof *vq->log * UIO_MAXIOV, GFP_KERNEL); 347 vq->heads = kmalloc(sizeof *vq->heads * UIO_MAXIOV, GFP_KERNEL); 348 if (!vq->indirect || !vq->log || !vq->heads) 349 goto err_nomem; 350 } 351 return 0; 352 353 err_nomem: 354 for (; i >= 0; --i) 355 vhost_vq_free_iovecs(dev->vqs[i]); 356 return -ENOMEM; 357 } 358 359 static void vhost_dev_free_iovecs(struct vhost_dev *dev) 360 { 361 int i; 362 363 for (i = 0; i < dev->nvqs; ++i) 364 vhost_vq_free_iovecs(dev->vqs[i]); 365 } 366 367 void vhost_dev_init(struct vhost_dev *dev, 368 struct vhost_virtqueue **vqs, int nvqs) 369 { 370 struct vhost_virtqueue *vq; 371 int i; 372 373 dev->vqs = vqs; 374 dev->nvqs = nvqs; 375 mutex_init(&dev->mutex); 376 dev->log_ctx = NULL; 377 dev->log_file = NULL; 378 dev->memory = NULL; 379 dev->mm = NULL; 380 spin_lock_init(&dev->work_lock); 381 INIT_LIST_HEAD(&dev->work_list); 382 dev->worker = NULL; 383 384 for (i = 0; i < dev->nvqs; ++i) { 385 vq = dev->vqs[i]; 386 vq->log = NULL; 387 vq->indirect = NULL; 388 vq->heads = NULL; 389 vq->dev = dev; 390 mutex_init(&vq->mutex); 391 vhost_vq_reset(dev, vq); 392 if (vq->handle_kick) 393 vhost_poll_init(&vq->poll, vq->handle_kick, 394 POLLIN, dev); 395 } 396 } 397 EXPORT_SYMBOL_GPL(vhost_dev_init); 398 399 /* Caller should have device mutex */ 400 long vhost_dev_check_owner(struct vhost_dev *dev) 401 { 402 /* Are you the owner? If not, I don't think you mean to do that */ 403 return dev->mm == current->mm ? 0 : -EPERM; 404 } 405 EXPORT_SYMBOL_GPL(vhost_dev_check_owner); 406 407 struct vhost_attach_cgroups_struct { 408 struct vhost_work work; 409 struct task_struct *owner; 410 int ret; 411 }; 412 413 static void vhost_attach_cgroups_work(struct vhost_work *work) 414 { 415 struct vhost_attach_cgroups_struct *s; 416 417 s = container_of(work, struct vhost_attach_cgroups_struct, work); 418 s->ret = cgroup_attach_task_all(s->owner, current); 419 } 420 421 static int vhost_attach_cgroups(struct vhost_dev *dev) 422 { 423 struct vhost_attach_cgroups_struct attach; 424 425 attach.owner = current; 426 vhost_work_init(&attach.work, vhost_attach_cgroups_work); 427 vhost_work_queue(dev, &attach.work); 428 vhost_work_flush(dev, &attach.work); 429 return attach.ret; 430 } 431 432 /* Caller should have device mutex */ 433 bool vhost_dev_has_owner(struct vhost_dev *dev) 434 { 435 return dev->mm; 436 } 437 EXPORT_SYMBOL_GPL(vhost_dev_has_owner); 438 439 /* Caller should have device mutex */ 440 long vhost_dev_set_owner(struct vhost_dev *dev) 441 { 442 struct task_struct *worker; 443 int err; 444 445 /* Is there an owner already? */ 446 if (vhost_dev_has_owner(dev)) { 447 err = -EBUSY; 448 goto err_mm; 449 } 450 451 /* No owner, become one */ 452 dev->mm = get_task_mm(current); 453 worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid); 454 if (IS_ERR(worker)) { 455 err = PTR_ERR(worker); 456 goto err_worker; 457 } 458 459 dev->worker = worker; 460 wake_up_process(worker); /* avoid contributing to loadavg */ 461 462 err = vhost_attach_cgroups(dev); 463 if (err) 464 goto err_cgroup; 465 466 err = vhost_dev_alloc_iovecs(dev); 467 if (err) 468 goto err_cgroup; 469 470 return 0; 471 err_cgroup: 472 kthread_stop(worker); 473 dev->worker = NULL; 474 err_worker: 475 if (dev->mm) 476 mmput(dev->mm); 477 dev->mm = NULL; 478 err_mm: 479 return err; 480 } 481 EXPORT_SYMBOL_GPL(vhost_dev_set_owner); 482 483 struct vhost_memory *vhost_dev_reset_owner_prepare(void) 484 { 485 return kmalloc(offsetof(struct vhost_memory, regions), GFP_KERNEL); 486 } 487 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner_prepare); 488 489 /* Caller should have device mutex */ 490 void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_memory *memory) 491 { 492 int i; 493 494 vhost_dev_cleanup(dev, true); 495 496 /* Restore memory to default empty mapping. */ 497 memory->nregions = 0; 498 dev->memory = memory; 499 /* We don't need VQ locks below since vhost_dev_cleanup makes sure 500 * VQs aren't running. 501 */ 502 for (i = 0; i < dev->nvqs; ++i) 503 dev->vqs[i]->memory = memory; 504 } 505 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner); 506 507 void vhost_dev_stop(struct vhost_dev *dev) 508 { 509 int i; 510 511 for (i = 0; i < dev->nvqs; ++i) { 512 if (dev->vqs[i]->kick && dev->vqs[i]->handle_kick) { 513 vhost_poll_stop(&dev->vqs[i]->poll); 514 vhost_poll_flush(&dev->vqs[i]->poll); 515 } 516 } 517 } 518 EXPORT_SYMBOL_GPL(vhost_dev_stop); 519 520 /* Caller should have device mutex if and only if locked is set */ 521 void vhost_dev_cleanup(struct vhost_dev *dev, bool locked) 522 { 523 int i; 524 525 for (i = 0; i < dev->nvqs; ++i) { 526 if (dev->vqs[i]->error_ctx) 527 eventfd_ctx_put(dev->vqs[i]->error_ctx); 528 if (dev->vqs[i]->error) 529 fput(dev->vqs[i]->error); 530 if (dev->vqs[i]->kick) 531 fput(dev->vqs[i]->kick); 532 if (dev->vqs[i]->call_ctx) 533 eventfd_ctx_put(dev->vqs[i]->call_ctx); 534 if (dev->vqs[i]->call) 535 fput(dev->vqs[i]->call); 536 vhost_vq_reset(dev, dev->vqs[i]); 537 } 538 vhost_dev_free_iovecs(dev); 539 if (dev->log_ctx) 540 eventfd_ctx_put(dev->log_ctx); 541 dev->log_ctx = NULL; 542 if (dev->log_file) 543 fput(dev->log_file); 544 dev->log_file = NULL; 545 /* No one will access memory at this point */ 546 kfree(dev->memory); 547 dev->memory = NULL; 548 WARN_ON(!list_empty(&dev->work_list)); 549 if (dev->worker) { 550 kthread_stop(dev->worker); 551 dev->worker = NULL; 552 } 553 if (dev->mm) 554 mmput(dev->mm); 555 dev->mm = NULL; 556 } 557 EXPORT_SYMBOL_GPL(vhost_dev_cleanup); 558 559 static int log_access_ok(void __user *log_base, u64 addr, unsigned long sz) 560 { 561 u64 a = addr / VHOST_PAGE_SIZE / 8; 562 563 /* Make sure 64 bit math will not overflow. */ 564 if (a > ULONG_MAX - (unsigned long)log_base || 565 a + (unsigned long)log_base > ULONG_MAX) 566 return 0; 567 568 return access_ok(VERIFY_WRITE, log_base + a, 569 (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8); 570 } 571 572 /* Caller should have vq mutex and device mutex. */ 573 static int vq_memory_access_ok(void __user *log_base, struct vhost_memory *mem, 574 int log_all) 575 { 576 int i; 577 578 if (!mem) 579 return 0; 580 581 for (i = 0; i < mem->nregions; ++i) { 582 struct vhost_memory_region *m = mem->regions + i; 583 unsigned long a = m->userspace_addr; 584 if (m->memory_size > ULONG_MAX) 585 return 0; 586 else if (!access_ok(VERIFY_WRITE, (void __user *)a, 587 m->memory_size)) 588 return 0; 589 else if (log_all && !log_access_ok(log_base, 590 m->guest_phys_addr, 591 m->memory_size)) 592 return 0; 593 } 594 return 1; 595 } 596 597 /* Can we switch to this memory table? */ 598 /* Caller should have device mutex but not vq mutex */ 599 static int memory_access_ok(struct vhost_dev *d, struct vhost_memory *mem, 600 int log_all) 601 { 602 int i; 603 604 for (i = 0; i < d->nvqs; ++i) { 605 int ok; 606 bool log; 607 608 mutex_lock(&d->vqs[i]->mutex); 609 log = log_all || vhost_has_feature(d->vqs[i], VHOST_F_LOG_ALL); 610 /* If ring is inactive, will check when it's enabled. */ 611 if (d->vqs[i]->private_data) 612 ok = vq_memory_access_ok(d->vqs[i]->log_base, mem, log); 613 else 614 ok = 1; 615 mutex_unlock(&d->vqs[i]->mutex); 616 if (!ok) 617 return 0; 618 } 619 return 1; 620 } 621 622 static int vq_access_ok(struct vhost_virtqueue *vq, unsigned int num, 623 struct vring_desc __user *desc, 624 struct vring_avail __user *avail, 625 struct vring_used __user *used) 626 { 627 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0; 628 return access_ok(VERIFY_READ, desc, num * sizeof *desc) && 629 access_ok(VERIFY_READ, avail, 630 sizeof *avail + num * sizeof *avail->ring + s) && 631 access_ok(VERIFY_WRITE, used, 632 sizeof *used + num * sizeof *used->ring + s); 633 } 634 635 /* Can we log writes? */ 636 /* Caller should have device mutex but not vq mutex */ 637 int vhost_log_access_ok(struct vhost_dev *dev) 638 { 639 return memory_access_ok(dev, dev->memory, 1); 640 } 641 EXPORT_SYMBOL_GPL(vhost_log_access_ok); 642 643 /* Verify access for write logging. */ 644 /* Caller should have vq mutex and device mutex */ 645 static int vq_log_access_ok(struct vhost_virtqueue *vq, 646 void __user *log_base) 647 { 648 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0; 649 650 return vq_memory_access_ok(log_base, vq->memory, 651 vhost_has_feature(vq, VHOST_F_LOG_ALL)) && 652 (!vq->log_used || log_access_ok(log_base, vq->log_addr, 653 sizeof *vq->used + 654 vq->num * sizeof *vq->used->ring + s)); 655 } 656 657 /* Can we start vq? */ 658 /* Caller should have vq mutex and device mutex */ 659 int vhost_vq_access_ok(struct vhost_virtqueue *vq) 660 { 661 return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used) && 662 vq_log_access_ok(vq, vq->log_base); 663 } 664 EXPORT_SYMBOL_GPL(vhost_vq_access_ok); 665 666 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m) 667 { 668 struct vhost_memory mem, *newmem, *oldmem; 669 unsigned long size = offsetof(struct vhost_memory, regions); 670 int i; 671 672 if (copy_from_user(&mem, m, size)) 673 return -EFAULT; 674 if (mem.padding) 675 return -EOPNOTSUPP; 676 if (mem.nregions > VHOST_MEMORY_MAX_NREGIONS) 677 return -E2BIG; 678 newmem = kmalloc(size + mem.nregions * sizeof *m->regions, GFP_KERNEL); 679 if (!newmem) 680 return -ENOMEM; 681 682 memcpy(newmem, &mem, size); 683 if (copy_from_user(newmem->regions, m->regions, 684 mem.nregions * sizeof *m->regions)) { 685 kfree(newmem); 686 return -EFAULT; 687 } 688 689 if (!memory_access_ok(d, newmem, 0)) { 690 kfree(newmem); 691 return -EFAULT; 692 } 693 oldmem = d->memory; 694 d->memory = newmem; 695 696 /* All memory accesses are done under some VQ mutex. */ 697 for (i = 0; i < d->nvqs; ++i) { 698 mutex_lock(&d->vqs[i]->mutex); 699 d->vqs[i]->memory = newmem; 700 mutex_unlock(&d->vqs[i]->mutex); 701 } 702 kfree(oldmem); 703 return 0; 704 } 705 706 long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp) 707 { 708 struct file *eventfp, *filep = NULL; 709 bool pollstart = false, pollstop = false; 710 struct eventfd_ctx *ctx = NULL; 711 u32 __user *idxp = argp; 712 struct vhost_virtqueue *vq; 713 struct vhost_vring_state s; 714 struct vhost_vring_file f; 715 struct vhost_vring_addr a; 716 u32 idx; 717 long r; 718 719 r = get_user(idx, idxp); 720 if (r < 0) 721 return r; 722 if (idx >= d->nvqs) 723 return -ENOBUFS; 724 725 vq = d->vqs[idx]; 726 727 mutex_lock(&vq->mutex); 728 729 switch (ioctl) { 730 case VHOST_SET_VRING_NUM: 731 /* Resizing ring with an active backend? 732 * You don't want to do that. */ 733 if (vq->private_data) { 734 r = -EBUSY; 735 break; 736 } 737 if (copy_from_user(&s, argp, sizeof s)) { 738 r = -EFAULT; 739 break; 740 } 741 if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) { 742 r = -EINVAL; 743 break; 744 } 745 vq->num = s.num; 746 break; 747 case VHOST_SET_VRING_BASE: 748 /* Moving base with an active backend? 749 * You don't want to do that. */ 750 if (vq->private_data) { 751 r = -EBUSY; 752 break; 753 } 754 if (copy_from_user(&s, argp, sizeof s)) { 755 r = -EFAULT; 756 break; 757 } 758 if (s.num > 0xffff) { 759 r = -EINVAL; 760 break; 761 } 762 vq->last_avail_idx = s.num; 763 /* Forget the cached index value. */ 764 vq->avail_idx = vq->last_avail_idx; 765 break; 766 case VHOST_GET_VRING_BASE: 767 s.index = idx; 768 s.num = vq->last_avail_idx; 769 if (copy_to_user(argp, &s, sizeof s)) 770 r = -EFAULT; 771 break; 772 case VHOST_SET_VRING_ADDR: 773 if (copy_from_user(&a, argp, sizeof a)) { 774 r = -EFAULT; 775 break; 776 } 777 if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) { 778 r = -EOPNOTSUPP; 779 break; 780 } 781 /* For 32bit, verify that the top 32bits of the user 782 data are set to zero. */ 783 if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr || 784 (u64)(unsigned long)a.used_user_addr != a.used_user_addr || 785 (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) { 786 r = -EFAULT; 787 break; 788 } 789 790 /* Make sure it's safe to cast pointers to vring types. */ 791 BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE); 792 BUILD_BUG_ON(__alignof__ *vq->used > VRING_USED_ALIGN_SIZE); 793 if ((a.avail_user_addr & (VRING_AVAIL_ALIGN_SIZE - 1)) || 794 (a.used_user_addr & (VRING_USED_ALIGN_SIZE - 1)) || 795 (a.log_guest_addr & (sizeof(u64) - 1))) { 796 r = -EINVAL; 797 break; 798 } 799 800 /* We only verify access here if backend is configured. 801 * If it is not, we don't as size might not have been setup. 802 * We will verify when backend is configured. */ 803 if (vq->private_data) { 804 if (!vq_access_ok(vq, vq->num, 805 (void __user *)(unsigned long)a.desc_user_addr, 806 (void __user *)(unsigned long)a.avail_user_addr, 807 (void __user *)(unsigned long)a.used_user_addr)) { 808 r = -EINVAL; 809 break; 810 } 811 812 /* Also validate log access for used ring if enabled. */ 813 if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) && 814 !log_access_ok(vq->log_base, a.log_guest_addr, 815 sizeof *vq->used + 816 vq->num * sizeof *vq->used->ring)) { 817 r = -EINVAL; 818 break; 819 } 820 } 821 822 vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG)); 823 vq->desc = (void __user *)(unsigned long)a.desc_user_addr; 824 vq->avail = (void __user *)(unsigned long)a.avail_user_addr; 825 vq->log_addr = a.log_guest_addr; 826 vq->used = (void __user *)(unsigned long)a.used_user_addr; 827 break; 828 case VHOST_SET_VRING_KICK: 829 if (copy_from_user(&f, argp, sizeof f)) { 830 r = -EFAULT; 831 break; 832 } 833 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); 834 if (IS_ERR(eventfp)) { 835 r = PTR_ERR(eventfp); 836 break; 837 } 838 if (eventfp != vq->kick) { 839 pollstop = (filep = vq->kick) != NULL; 840 pollstart = (vq->kick = eventfp) != NULL; 841 } else 842 filep = eventfp; 843 break; 844 case VHOST_SET_VRING_CALL: 845 if (copy_from_user(&f, argp, sizeof f)) { 846 r = -EFAULT; 847 break; 848 } 849 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); 850 if (IS_ERR(eventfp)) { 851 r = PTR_ERR(eventfp); 852 break; 853 } 854 if (eventfp != vq->call) { 855 filep = vq->call; 856 ctx = vq->call_ctx; 857 vq->call = eventfp; 858 vq->call_ctx = eventfp ? 859 eventfd_ctx_fileget(eventfp) : NULL; 860 } else 861 filep = eventfp; 862 break; 863 case VHOST_SET_VRING_ERR: 864 if (copy_from_user(&f, argp, sizeof f)) { 865 r = -EFAULT; 866 break; 867 } 868 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); 869 if (IS_ERR(eventfp)) { 870 r = PTR_ERR(eventfp); 871 break; 872 } 873 if (eventfp != vq->error) { 874 filep = vq->error; 875 vq->error = eventfp; 876 ctx = vq->error_ctx; 877 vq->error_ctx = eventfp ? 878 eventfd_ctx_fileget(eventfp) : NULL; 879 } else 880 filep = eventfp; 881 break; 882 case VHOST_SET_VRING_ENDIAN: 883 r = vhost_set_vring_endian(vq, argp); 884 break; 885 case VHOST_GET_VRING_ENDIAN: 886 r = vhost_get_vring_endian(vq, idx, argp); 887 break; 888 default: 889 r = -ENOIOCTLCMD; 890 } 891 892 if (pollstop && vq->handle_kick) 893 vhost_poll_stop(&vq->poll); 894 895 if (ctx) 896 eventfd_ctx_put(ctx); 897 if (filep) 898 fput(filep); 899 900 if (pollstart && vq->handle_kick) 901 r = vhost_poll_start(&vq->poll, vq->kick); 902 903 mutex_unlock(&vq->mutex); 904 905 if (pollstop && vq->handle_kick) 906 vhost_poll_flush(&vq->poll); 907 return r; 908 } 909 EXPORT_SYMBOL_GPL(vhost_vring_ioctl); 910 911 /* Caller must have device mutex */ 912 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp) 913 { 914 struct file *eventfp, *filep = NULL; 915 struct eventfd_ctx *ctx = NULL; 916 u64 p; 917 long r; 918 int i, fd; 919 920 /* If you are not the owner, you can become one */ 921 if (ioctl == VHOST_SET_OWNER) { 922 r = vhost_dev_set_owner(d); 923 goto done; 924 } 925 926 /* You must be the owner to do anything else */ 927 r = vhost_dev_check_owner(d); 928 if (r) 929 goto done; 930 931 switch (ioctl) { 932 case VHOST_SET_MEM_TABLE: 933 r = vhost_set_memory(d, argp); 934 break; 935 case VHOST_SET_LOG_BASE: 936 if (copy_from_user(&p, argp, sizeof p)) { 937 r = -EFAULT; 938 break; 939 } 940 if ((u64)(unsigned long)p != p) { 941 r = -EFAULT; 942 break; 943 } 944 for (i = 0; i < d->nvqs; ++i) { 945 struct vhost_virtqueue *vq; 946 void __user *base = (void __user *)(unsigned long)p; 947 vq = d->vqs[i]; 948 mutex_lock(&vq->mutex); 949 /* If ring is inactive, will check when it's enabled. */ 950 if (vq->private_data && !vq_log_access_ok(vq, base)) 951 r = -EFAULT; 952 else 953 vq->log_base = base; 954 mutex_unlock(&vq->mutex); 955 } 956 break; 957 case VHOST_SET_LOG_FD: 958 r = get_user(fd, (int __user *)argp); 959 if (r < 0) 960 break; 961 eventfp = fd == -1 ? NULL : eventfd_fget(fd); 962 if (IS_ERR(eventfp)) { 963 r = PTR_ERR(eventfp); 964 break; 965 } 966 if (eventfp != d->log_file) { 967 filep = d->log_file; 968 ctx = d->log_ctx; 969 d->log_ctx = eventfp ? 970 eventfd_ctx_fileget(eventfp) : NULL; 971 } else 972 filep = eventfp; 973 for (i = 0; i < d->nvqs; ++i) { 974 mutex_lock(&d->vqs[i]->mutex); 975 d->vqs[i]->log_ctx = d->log_ctx; 976 mutex_unlock(&d->vqs[i]->mutex); 977 } 978 if (ctx) 979 eventfd_ctx_put(ctx); 980 if (filep) 981 fput(filep); 982 break; 983 default: 984 r = -ENOIOCTLCMD; 985 break; 986 } 987 done: 988 return r; 989 } 990 EXPORT_SYMBOL_GPL(vhost_dev_ioctl); 991 992 static const struct vhost_memory_region *find_region(struct vhost_memory *mem, 993 __u64 addr, __u32 len) 994 { 995 struct vhost_memory_region *reg; 996 int i; 997 998 /* linear search is not brilliant, but we really have on the order of 6 999 * regions in practice */ 1000 for (i = 0; i < mem->nregions; ++i) { 1001 reg = mem->regions + i; 1002 if (reg->guest_phys_addr <= addr && 1003 reg->guest_phys_addr + reg->memory_size - 1 >= addr) 1004 return reg; 1005 } 1006 return NULL; 1007 } 1008 1009 /* TODO: This is really inefficient. We need something like get_user() 1010 * (instruction directly accesses the data, with an exception table entry 1011 * returning -EFAULT). See Documentation/x86/exception-tables.txt. 1012 */ 1013 static int set_bit_to_user(int nr, void __user *addr) 1014 { 1015 unsigned long log = (unsigned long)addr; 1016 struct page *page; 1017 void *base; 1018 int bit = nr + (log % PAGE_SIZE) * 8; 1019 int r; 1020 1021 r = get_user_pages_fast(log, 1, 1, &page); 1022 if (r < 0) 1023 return r; 1024 BUG_ON(r != 1); 1025 base = kmap_atomic(page); 1026 set_bit(bit, base); 1027 kunmap_atomic(base); 1028 set_page_dirty_lock(page); 1029 put_page(page); 1030 return 0; 1031 } 1032 1033 static int log_write(void __user *log_base, 1034 u64 write_address, u64 write_length) 1035 { 1036 u64 write_page = write_address / VHOST_PAGE_SIZE; 1037 int r; 1038 1039 if (!write_length) 1040 return 0; 1041 write_length += write_address % VHOST_PAGE_SIZE; 1042 for (;;) { 1043 u64 base = (u64)(unsigned long)log_base; 1044 u64 log = base + write_page / 8; 1045 int bit = write_page % 8; 1046 if ((u64)(unsigned long)log != log) 1047 return -EFAULT; 1048 r = set_bit_to_user(bit, (void __user *)(unsigned long)log); 1049 if (r < 0) 1050 return r; 1051 if (write_length <= VHOST_PAGE_SIZE) 1052 break; 1053 write_length -= VHOST_PAGE_SIZE; 1054 write_page += 1; 1055 } 1056 return r; 1057 } 1058 1059 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log, 1060 unsigned int log_num, u64 len) 1061 { 1062 int i, r; 1063 1064 /* Make sure data written is seen before log. */ 1065 smp_wmb(); 1066 for (i = 0; i < log_num; ++i) { 1067 u64 l = min(log[i].len, len); 1068 r = log_write(vq->log_base, log[i].addr, l); 1069 if (r < 0) 1070 return r; 1071 len -= l; 1072 if (!len) { 1073 if (vq->log_ctx) 1074 eventfd_signal(vq->log_ctx, 1); 1075 return 0; 1076 } 1077 } 1078 /* Length written exceeds what we have stored. This is a bug. */ 1079 BUG(); 1080 return 0; 1081 } 1082 EXPORT_SYMBOL_GPL(vhost_log_write); 1083 1084 static int vhost_update_used_flags(struct vhost_virtqueue *vq) 1085 { 1086 void __user *used; 1087 if (__put_user(cpu_to_vhost16(vq, vq->used_flags), &vq->used->flags) < 0) 1088 return -EFAULT; 1089 if (unlikely(vq->log_used)) { 1090 /* Make sure the flag is seen before log. */ 1091 smp_wmb(); 1092 /* Log used flag write. */ 1093 used = &vq->used->flags; 1094 log_write(vq->log_base, vq->log_addr + 1095 (used - (void __user *)vq->used), 1096 sizeof vq->used->flags); 1097 if (vq->log_ctx) 1098 eventfd_signal(vq->log_ctx, 1); 1099 } 1100 return 0; 1101 } 1102 1103 static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event) 1104 { 1105 if (__put_user(cpu_to_vhost16(vq, vq->avail_idx), vhost_avail_event(vq))) 1106 return -EFAULT; 1107 if (unlikely(vq->log_used)) { 1108 void __user *used; 1109 /* Make sure the event is seen before log. */ 1110 smp_wmb(); 1111 /* Log avail event write */ 1112 used = vhost_avail_event(vq); 1113 log_write(vq->log_base, vq->log_addr + 1114 (used - (void __user *)vq->used), 1115 sizeof *vhost_avail_event(vq)); 1116 if (vq->log_ctx) 1117 eventfd_signal(vq->log_ctx, 1); 1118 } 1119 return 0; 1120 } 1121 1122 int vhost_init_used(struct vhost_virtqueue *vq) 1123 { 1124 __virtio16 last_used_idx; 1125 int r; 1126 if (!vq->private_data) { 1127 vq->is_le = virtio_legacy_is_little_endian(); 1128 return 0; 1129 } 1130 1131 vhost_init_is_le(vq); 1132 1133 r = vhost_update_used_flags(vq); 1134 if (r) 1135 return r; 1136 vq->signalled_used_valid = false; 1137 if (!access_ok(VERIFY_READ, &vq->used->idx, sizeof vq->used->idx)) 1138 return -EFAULT; 1139 r = __get_user(last_used_idx, &vq->used->idx); 1140 if (r) 1141 return r; 1142 vq->last_used_idx = vhost16_to_cpu(vq, last_used_idx); 1143 return 0; 1144 } 1145 EXPORT_SYMBOL_GPL(vhost_init_used); 1146 1147 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len, 1148 struct iovec iov[], int iov_size) 1149 { 1150 const struct vhost_memory_region *reg; 1151 struct vhost_memory *mem; 1152 struct iovec *_iov; 1153 u64 s = 0; 1154 int ret = 0; 1155 1156 mem = vq->memory; 1157 while ((u64)len > s) { 1158 u64 size; 1159 if (unlikely(ret >= iov_size)) { 1160 ret = -ENOBUFS; 1161 break; 1162 } 1163 reg = find_region(mem, addr, len); 1164 if (unlikely(!reg)) { 1165 ret = -EFAULT; 1166 break; 1167 } 1168 _iov = iov + ret; 1169 size = reg->memory_size - addr + reg->guest_phys_addr; 1170 _iov->iov_len = min((u64)len - s, size); 1171 _iov->iov_base = (void __user *)(unsigned long) 1172 (reg->userspace_addr + addr - reg->guest_phys_addr); 1173 s += size; 1174 addr += size; 1175 ++ret; 1176 } 1177 1178 return ret; 1179 } 1180 1181 /* Each buffer in the virtqueues is actually a chain of descriptors. This 1182 * function returns the next descriptor in the chain, 1183 * or -1U if we're at the end. */ 1184 static unsigned next_desc(struct vhost_virtqueue *vq, struct vring_desc *desc) 1185 { 1186 unsigned int next; 1187 1188 /* If this descriptor says it doesn't chain, we're done. */ 1189 if (!(desc->flags & cpu_to_vhost16(vq, VRING_DESC_F_NEXT))) 1190 return -1U; 1191 1192 /* Check they're not leading us off end of descriptors. */ 1193 next = vhost16_to_cpu(vq, desc->next); 1194 /* Make sure compiler knows to grab that: we don't want it changing! */ 1195 /* We will use the result as an index in an array, so most 1196 * architectures only need a compiler barrier here. */ 1197 read_barrier_depends(); 1198 1199 return next; 1200 } 1201 1202 static int get_indirect(struct vhost_virtqueue *vq, 1203 struct iovec iov[], unsigned int iov_size, 1204 unsigned int *out_num, unsigned int *in_num, 1205 struct vhost_log *log, unsigned int *log_num, 1206 struct vring_desc *indirect) 1207 { 1208 struct vring_desc desc; 1209 unsigned int i = 0, count, found = 0; 1210 u32 len = vhost32_to_cpu(vq, indirect->len); 1211 struct iov_iter from; 1212 int ret; 1213 1214 /* Sanity check */ 1215 if (unlikely(len % sizeof desc)) { 1216 vq_err(vq, "Invalid length in indirect descriptor: " 1217 "len 0x%llx not multiple of 0x%zx\n", 1218 (unsigned long long)len, 1219 sizeof desc); 1220 return -EINVAL; 1221 } 1222 1223 ret = translate_desc(vq, vhost64_to_cpu(vq, indirect->addr), len, vq->indirect, 1224 UIO_MAXIOV); 1225 if (unlikely(ret < 0)) { 1226 vq_err(vq, "Translation failure %d in indirect.\n", ret); 1227 return ret; 1228 } 1229 iov_iter_init(&from, READ, vq->indirect, ret, len); 1230 1231 /* We will use the result as an address to read from, so most 1232 * architectures only need a compiler barrier here. */ 1233 read_barrier_depends(); 1234 1235 count = len / sizeof desc; 1236 /* Buffers are chained via a 16 bit next field, so 1237 * we can have at most 2^16 of these. */ 1238 if (unlikely(count > USHRT_MAX + 1)) { 1239 vq_err(vq, "Indirect buffer length too big: %d\n", 1240 indirect->len); 1241 return -E2BIG; 1242 } 1243 1244 do { 1245 unsigned iov_count = *in_num + *out_num; 1246 if (unlikely(++found > count)) { 1247 vq_err(vq, "Loop detected: last one at %u " 1248 "indirect size %u\n", 1249 i, count); 1250 return -EINVAL; 1251 } 1252 if (unlikely(copy_from_iter(&desc, sizeof(desc), &from) != 1253 sizeof(desc))) { 1254 vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n", 1255 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc); 1256 return -EINVAL; 1257 } 1258 if (unlikely(desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT))) { 1259 vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n", 1260 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc); 1261 return -EINVAL; 1262 } 1263 1264 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr), 1265 vhost32_to_cpu(vq, desc.len), iov + iov_count, 1266 iov_size - iov_count); 1267 if (unlikely(ret < 0)) { 1268 vq_err(vq, "Translation failure %d indirect idx %d\n", 1269 ret, i); 1270 return ret; 1271 } 1272 /* If this is an input descriptor, increment that count. */ 1273 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE)) { 1274 *in_num += ret; 1275 if (unlikely(log)) { 1276 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr); 1277 log[*log_num].len = vhost32_to_cpu(vq, desc.len); 1278 ++*log_num; 1279 } 1280 } else { 1281 /* If it's an output descriptor, they're all supposed 1282 * to come before any input descriptors. */ 1283 if (unlikely(*in_num)) { 1284 vq_err(vq, "Indirect descriptor " 1285 "has out after in: idx %d\n", i); 1286 return -EINVAL; 1287 } 1288 *out_num += ret; 1289 } 1290 } while ((i = next_desc(vq, &desc)) != -1); 1291 return 0; 1292 } 1293 1294 /* This looks in the virtqueue and for the first available buffer, and converts 1295 * it to an iovec for convenient access. Since descriptors consist of some 1296 * number of output then some number of input descriptors, it's actually two 1297 * iovecs, but we pack them into one and note how many of each there were. 1298 * 1299 * This function returns the descriptor number found, or vq->num (which is 1300 * never a valid descriptor number) if none was found. A negative code is 1301 * returned on error. */ 1302 int vhost_get_vq_desc(struct vhost_virtqueue *vq, 1303 struct iovec iov[], unsigned int iov_size, 1304 unsigned int *out_num, unsigned int *in_num, 1305 struct vhost_log *log, unsigned int *log_num) 1306 { 1307 struct vring_desc desc; 1308 unsigned int i, head, found = 0; 1309 u16 last_avail_idx; 1310 __virtio16 avail_idx; 1311 __virtio16 ring_head; 1312 int ret; 1313 1314 /* Check it isn't doing very strange things with descriptor numbers. */ 1315 last_avail_idx = vq->last_avail_idx; 1316 if (unlikely(__get_user(avail_idx, &vq->avail->idx))) { 1317 vq_err(vq, "Failed to access avail idx at %p\n", 1318 &vq->avail->idx); 1319 return -EFAULT; 1320 } 1321 vq->avail_idx = vhost16_to_cpu(vq, avail_idx); 1322 1323 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) { 1324 vq_err(vq, "Guest moved used index from %u to %u", 1325 last_avail_idx, vq->avail_idx); 1326 return -EFAULT; 1327 } 1328 1329 /* If there's nothing new since last we looked, return invalid. */ 1330 if (vq->avail_idx == last_avail_idx) 1331 return vq->num; 1332 1333 /* Only get avail ring entries after they have been exposed by guest. */ 1334 smp_rmb(); 1335 1336 /* Grab the next descriptor number they're advertising, and increment 1337 * the index we've seen. */ 1338 if (unlikely(__get_user(ring_head, 1339 &vq->avail->ring[last_avail_idx % vq->num]))) { 1340 vq_err(vq, "Failed to read head: idx %d address %p\n", 1341 last_avail_idx, 1342 &vq->avail->ring[last_avail_idx % vq->num]); 1343 return -EFAULT; 1344 } 1345 1346 head = vhost16_to_cpu(vq, ring_head); 1347 1348 /* If their number is silly, that's an error. */ 1349 if (unlikely(head >= vq->num)) { 1350 vq_err(vq, "Guest says index %u > %u is available", 1351 head, vq->num); 1352 return -EINVAL; 1353 } 1354 1355 /* When we start there are none of either input nor output. */ 1356 *out_num = *in_num = 0; 1357 if (unlikely(log)) 1358 *log_num = 0; 1359 1360 i = head; 1361 do { 1362 unsigned iov_count = *in_num + *out_num; 1363 if (unlikely(i >= vq->num)) { 1364 vq_err(vq, "Desc index is %u > %u, head = %u", 1365 i, vq->num, head); 1366 return -EINVAL; 1367 } 1368 if (unlikely(++found > vq->num)) { 1369 vq_err(vq, "Loop detected: last one at %u " 1370 "vq size %u head %u\n", 1371 i, vq->num, head); 1372 return -EINVAL; 1373 } 1374 ret = __copy_from_user(&desc, vq->desc + i, sizeof desc); 1375 if (unlikely(ret)) { 1376 vq_err(vq, "Failed to get descriptor: idx %d addr %p\n", 1377 i, vq->desc + i); 1378 return -EFAULT; 1379 } 1380 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT)) { 1381 ret = get_indirect(vq, iov, iov_size, 1382 out_num, in_num, 1383 log, log_num, &desc); 1384 if (unlikely(ret < 0)) { 1385 vq_err(vq, "Failure detected " 1386 "in indirect descriptor at idx %d\n", i); 1387 return ret; 1388 } 1389 continue; 1390 } 1391 1392 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr), 1393 vhost32_to_cpu(vq, desc.len), iov + iov_count, 1394 iov_size - iov_count); 1395 if (unlikely(ret < 0)) { 1396 vq_err(vq, "Translation failure %d descriptor idx %d\n", 1397 ret, i); 1398 return ret; 1399 } 1400 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE)) { 1401 /* If this is an input descriptor, 1402 * increment that count. */ 1403 *in_num += ret; 1404 if (unlikely(log)) { 1405 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr); 1406 log[*log_num].len = vhost32_to_cpu(vq, desc.len); 1407 ++*log_num; 1408 } 1409 } else { 1410 /* If it's an output descriptor, they're all supposed 1411 * to come before any input descriptors. */ 1412 if (unlikely(*in_num)) { 1413 vq_err(vq, "Descriptor has out after in: " 1414 "idx %d\n", i); 1415 return -EINVAL; 1416 } 1417 *out_num += ret; 1418 } 1419 } while ((i = next_desc(vq, &desc)) != -1); 1420 1421 /* On success, increment avail index. */ 1422 vq->last_avail_idx++; 1423 1424 /* Assume notifications from guest are disabled at this point, 1425 * if they aren't we would need to update avail_event index. */ 1426 BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY)); 1427 return head; 1428 } 1429 EXPORT_SYMBOL_GPL(vhost_get_vq_desc); 1430 1431 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */ 1432 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n) 1433 { 1434 vq->last_avail_idx -= n; 1435 } 1436 EXPORT_SYMBOL_GPL(vhost_discard_vq_desc); 1437 1438 /* After we've used one of their buffers, we tell them about it. We'll then 1439 * want to notify the guest, using eventfd. */ 1440 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len) 1441 { 1442 struct vring_used_elem heads = { 1443 cpu_to_vhost32(vq, head), 1444 cpu_to_vhost32(vq, len) 1445 }; 1446 1447 return vhost_add_used_n(vq, &heads, 1); 1448 } 1449 EXPORT_SYMBOL_GPL(vhost_add_used); 1450 1451 static int __vhost_add_used_n(struct vhost_virtqueue *vq, 1452 struct vring_used_elem *heads, 1453 unsigned count) 1454 { 1455 struct vring_used_elem __user *used; 1456 u16 old, new; 1457 int start; 1458 1459 start = vq->last_used_idx % vq->num; 1460 used = vq->used->ring + start; 1461 if (count == 1) { 1462 if (__put_user(heads[0].id, &used->id)) { 1463 vq_err(vq, "Failed to write used id"); 1464 return -EFAULT; 1465 } 1466 if (__put_user(heads[0].len, &used->len)) { 1467 vq_err(vq, "Failed to write used len"); 1468 return -EFAULT; 1469 } 1470 } else if (__copy_to_user(used, heads, count * sizeof *used)) { 1471 vq_err(vq, "Failed to write used"); 1472 return -EFAULT; 1473 } 1474 if (unlikely(vq->log_used)) { 1475 /* Make sure data is seen before log. */ 1476 smp_wmb(); 1477 /* Log used ring entry write. */ 1478 log_write(vq->log_base, 1479 vq->log_addr + 1480 ((void __user *)used - (void __user *)vq->used), 1481 count * sizeof *used); 1482 } 1483 old = vq->last_used_idx; 1484 new = (vq->last_used_idx += count); 1485 /* If the driver never bothers to signal in a very long while, 1486 * used index might wrap around. If that happens, invalidate 1487 * signalled_used index we stored. TODO: make sure driver 1488 * signals at least once in 2^16 and remove this. */ 1489 if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old))) 1490 vq->signalled_used_valid = false; 1491 return 0; 1492 } 1493 1494 /* After we've used one of their buffers, we tell them about it. We'll then 1495 * want to notify the guest, using eventfd. */ 1496 int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads, 1497 unsigned count) 1498 { 1499 int start, n, r; 1500 1501 start = vq->last_used_idx % vq->num; 1502 n = vq->num - start; 1503 if (n < count) { 1504 r = __vhost_add_used_n(vq, heads, n); 1505 if (r < 0) 1506 return r; 1507 heads += n; 1508 count -= n; 1509 } 1510 r = __vhost_add_used_n(vq, heads, count); 1511 1512 /* Make sure buffer is written before we update index. */ 1513 smp_wmb(); 1514 if (__put_user(cpu_to_vhost16(vq, vq->last_used_idx), &vq->used->idx)) { 1515 vq_err(vq, "Failed to increment used idx"); 1516 return -EFAULT; 1517 } 1518 if (unlikely(vq->log_used)) { 1519 /* Log used index update. */ 1520 log_write(vq->log_base, 1521 vq->log_addr + offsetof(struct vring_used, idx), 1522 sizeof vq->used->idx); 1523 if (vq->log_ctx) 1524 eventfd_signal(vq->log_ctx, 1); 1525 } 1526 return r; 1527 } 1528 EXPORT_SYMBOL_GPL(vhost_add_used_n); 1529 1530 static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) 1531 { 1532 __u16 old, new; 1533 __virtio16 event; 1534 bool v; 1535 /* Flush out used index updates. This is paired 1536 * with the barrier that the Guest executes when enabling 1537 * interrupts. */ 1538 smp_mb(); 1539 1540 if (vhost_has_feature(vq, VIRTIO_F_NOTIFY_ON_EMPTY) && 1541 unlikely(vq->avail_idx == vq->last_avail_idx)) 1542 return true; 1543 1544 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) { 1545 __virtio16 flags; 1546 if (__get_user(flags, &vq->avail->flags)) { 1547 vq_err(vq, "Failed to get flags"); 1548 return true; 1549 } 1550 return !(flags & cpu_to_vhost16(vq, VRING_AVAIL_F_NO_INTERRUPT)); 1551 } 1552 old = vq->signalled_used; 1553 v = vq->signalled_used_valid; 1554 new = vq->signalled_used = vq->last_used_idx; 1555 vq->signalled_used_valid = true; 1556 1557 if (unlikely(!v)) 1558 return true; 1559 1560 if (__get_user(event, vhost_used_event(vq))) { 1561 vq_err(vq, "Failed to get used event idx"); 1562 return true; 1563 } 1564 return vring_need_event(vhost16_to_cpu(vq, event), new, old); 1565 } 1566 1567 /* This actually signals the guest, using eventfd. */ 1568 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq) 1569 { 1570 /* Signal the Guest tell them we used something up. */ 1571 if (vq->call_ctx && vhost_notify(dev, vq)) 1572 eventfd_signal(vq->call_ctx, 1); 1573 } 1574 EXPORT_SYMBOL_GPL(vhost_signal); 1575 1576 /* And here's the combo meal deal. Supersize me! */ 1577 void vhost_add_used_and_signal(struct vhost_dev *dev, 1578 struct vhost_virtqueue *vq, 1579 unsigned int head, int len) 1580 { 1581 vhost_add_used(vq, head, len); 1582 vhost_signal(dev, vq); 1583 } 1584 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal); 1585 1586 /* multi-buffer version of vhost_add_used_and_signal */ 1587 void vhost_add_used_and_signal_n(struct vhost_dev *dev, 1588 struct vhost_virtqueue *vq, 1589 struct vring_used_elem *heads, unsigned count) 1590 { 1591 vhost_add_used_n(vq, heads, count); 1592 vhost_signal(dev, vq); 1593 } 1594 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n); 1595 1596 /* OK, now we need to know about added descriptors. */ 1597 bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) 1598 { 1599 __virtio16 avail_idx; 1600 int r; 1601 1602 if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY)) 1603 return false; 1604 vq->used_flags &= ~VRING_USED_F_NO_NOTIFY; 1605 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) { 1606 r = vhost_update_used_flags(vq); 1607 if (r) { 1608 vq_err(vq, "Failed to enable notification at %p: %d\n", 1609 &vq->used->flags, r); 1610 return false; 1611 } 1612 } else { 1613 r = vhost_update_avail_event(vq, vq->avail_idx); 1614 if (r) { 1615 vq_err(vq, "Failed to update avail event index at %p: %d\n", 1616 vhost_avail_event(vq), r); 1617 return false; 1618 } 1619 } 1620 /* They could have slipped one in as we were doing that: make 1621 * sure it's written, then check again. */ 1622 smp_mb(); 1623 r = __get_user(avail_idx, &vq->avail->idx); 1624 if (r) { 1625 vq_err(vq, "Failed to check avail idx at %p: %d\n", 1626 &vq->avail->idx, r); 1627 return false; 1628 } 1629 1630 return vhost16_to_cpu(vq, avail_idx) != vq->avail_idx; 1631 } 1632 EXPORT_SYMBOL_GPL(vhost_enable_notify); 1633 1634 /* We don't need to be notified again. */ 1635 void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) 1636 { 1637 int r; 1638 1639 if (vq->used_flags & VRING_USED_F_NO_NOTIFY) 1640 return; 1641 vq->used_flags |= VRING_USED_F_NO_NOTIFY; 1642 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) { 1643 r = vhost_update_used_flags(vq); 1644 if (r) 1645 vq_err(vq, "Failed to enable notification at %p: %d\n", 1646 &vq->used->flags, r); 1647 } 1648 } 1649 EXPORT_SYMBOL_GPL(vhost_disable_notify); 1650 1651 static int __init vhost_init(void) 1652 { 1653 return 0; 1654 } 1655 1656 static void __exit vhost_exit(void) 1657 { 1658 } 1659 1660 module_init(vhost_init); 1661 module_exit(vhost_exit); 1662 1663 MODULE_VERSION("0.0.1"); 1664 MODULE_LICENSE("GPL v2"); 1665 MODULE_AUTHOR("Michael S. Tsirkin"); 1666 MODULE_DESCRIPTION("Host kernel accelerator for virtio"); 1667