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/socket.h> /* memcpy_fromiovec */ 17 #include <linux/mm.h> 18 #include <linux/mmu_context.h> 19 #include <linux/miscdevice.h> 20 #include <linux/mutex.h> 21 #include <linux/rcupdate.h> 22 #include <linux/poll.h> 23 #include <linux/file.h> 24 #include <linux/highmem.h> 25 #include <linux/slab.h> 26 #include <linux/kthread.h> 27 #include <linux/cgroup.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) ((u16 __user *)&vq->avail->ring[vq->num]) 37 #define vhost_avail_event(vq) ((u16 __user *)&vq->used->ring[vq->num]) 38 39 static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh, 40 poll_table *pt) 41 { 42 struct vhost_poll *poll; 43 44 poll = container_of(pt, struct vhost_poll, table); 45 poll->wqh = wqh; 46 add_wait_queue(wqh, &poll->wait); 47 } 48 49 static int vhost_poll_wakeup(wait_queue_t *wait, unsigned mode, int sync, 50 void *key) 51 { 52 struct vhost_poll *poll = container_of(wait, struct vhost_poll, wait); 53 54 if (!((unsigned long)key & poll->mask)) 55 return 0; 56 57 vhost_poll_queue(poll); 58 return 0; 59 } 60 61 void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn) 62 { 63 INIT_LIST_HEAD(&work->node); 64 work->fn = fn; 65 init_waitqueue_head(&work->done); 66 work->flushing = 0; 67 work->queue_seq = work->done_seq = 0; 68 } 69 70 /* Init poll structure */ 71 void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn, 72 unsigned long mask, struct vhost_dev *dev) 73 { 74 init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup); 75 init_poll_funcptr(&poll->table, vhost_poll_func); 76 poll->mask = mask; 77 poll->dev = dev; 78 poll->wqh = NULL; 79 80 vhost_work_init(&poll->work, fn); 81 } 82 83 /* Start polling a file. We add ourselves to file's wait queue. The caller must 84 * keep a reference to a file until after vhost_poll_stop is called. */ 85 int vhost_poll_start(struct vhost_poll *poll, struct file *file) 86 { 87 unsigned long mask; 88 int ret = 0; 89 90 if (poll->wqh) 91 return 0; 92 93 mask = file->f_op->poll(file, &poll->table); 94 if (mask) 95 vhost_poll_wakeup(&poll->wait, 0, 0, (void *)mask); 96 if (mask & POLLERR) { 97 if (poll->wqh) 98 remove_wait_queue(poll->wqh, &poll->wait); 99 ret = -EINVAL; 100 } 101 102 return ret; 103 } 104 105 /* Stop polling a file. After this function returns, it becomes safe to drop the 106 * file reference. You must also flush afterwards. */ 107 void vhost_poll_stop(struct vhost_poll *poll) 108 { 109 if (poll->wqh) { 110 remove_wait_queue(poll->wqh, &poll->wait); 111 poll->wqh = NULL; 112 } 113 } 114 115 static bool vhost_work_seq_done(struct vhost_dev *dev, struct vhost_work *work, 116 unsigned seq) 117 { 118 int left; 119 120 spin_lock_irq(&dev->work_lock); 121 left = seq - work->done_seq; 122 spin_unlock_irq(&dev->work_lock); 123 return left <= 0; 124 } 125 126 static void vhost_work_flush(struct vhost_dev *dev, struct vhost_work *work) 127 { 128 unsigned seq; 129 int flushing; 130 131 spin_lock_irq(&dev->work_lock); 132 seq = work->queue_seq; 133 work->flushing++; 134 spin_unlock_irq(&dev->work_lock); 135 wait_event(work->done, vhost_work_seq_done(dev, work, seq)); 136 spin_lock_irq(&dev->work_lock); 137 flushing = --work->flushing; 138 spin_unlock_irq(&dev->work_lock); 139 BUG_ON(flushing < 0); 140 } 141 142 /* Flush any work that has been scheduled. When calling this, don't hold any 143 * locks that are also used by the callback. */ 144 void vhost_poll_flush(struct vhost_poll *poll) 145 { 146 vhost_work_flush(poll->dev, &poll->work); 147 } 148 149 void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work) 150 { 151 unsigned long flags; 152 153 spin_lock_irqsave(&dev->work_lock, flags); 154 if (list_empty(&work->node)) { 155 list_add_tail(&work->node, &dev->work_list); 156 work->queue_seq++; 157 wake_up_process(dev->worker); 158 } 159 spin_unlock_irqrestore(&dev->work_lock, flags); 160 } 161 162 void vhost_poll_queue(struct vhost_poll *poll) 163 { 164 vhost_work_queue(poll->dev, &poll->work); 165 } 166 167 static void vhost_vq_reset(struct vhost_dev *dev, 168 struct vhost_virtqueue *vq) 169 { 170 vq->num = 1; 171 vq->desc = NULL; 172 vq->avail = NULL; 173 vq->used = NULL; 174 vq->last_avail_idx = 0; 175 vq->avail_idx = 0; 176 vq->last_used_idx = 0; 177 vq->signalled_used = 0; 178 vq->signalled_used_valid = false; 179 vq->used_flags = 0; 180 vq->log_used = false; 181 vq->log_addr = -1ull; 182 vq->private_data = NULL; 183 vq->log_base = NULL; 184 vq->error_ctx = NULL; 185 vq->error = NULL; 186 vq->kick = NULL; 187 vq->call_ctx = NULL; 188 vq->call = NULL; 189 vq->log_ctx = NULL; 190 } 191 192 static int vhost_worker(void *data) 193 { 194 struct vhost_dev *dev = data; 195 struct vhost_work *work = NULL; 196 unsigned uninitialized_var(seq); 197 mm_segment_t oldfs = get_fs(); 198 199 set_fs(USER_DS); 200 use_mm(dev->mm); 201 202 for (;;) { 203 /* mb paired w/ kthread_stop */ 204 set_current_state(TASK_INTERRUPTIBLE); 205 206 spin_lock_irq(&dev->work_lock); 207 if (work) { 208 work->done_seq = seq; 209 if (work->flushing) 210 wake_up_all(&work->done); 211 } 212 213 if (kthread_should_stop()) { 214 spin_unlock_irq(&dev->work_lock); 215 __set_current_state(TASK_RUNNING); 216 break; 217 } 218 if (!list_empty(&dev->work_list)) { 219 work = list_first_entry(&dev->work_list, 220 struct vhost_work, node); 221 list_del_init(&work->node); 222 seq = work->queue_seq; 223 } else 224 work = NULL; 225 spin_unlock_irq(&dev->work_lock); 226 227 if (work) { 228 __set_current_state(TASK_RUNNING); 229 work->fn(work); 230 if (need_resched()) 231 schedule(); 232 } else 233 schedule(); 234 235 } 236 unuse_mm(dev->mm); 237 set_fs(oldfs); 238 return 0; 239 } 240 241 static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq) 242 { 243 kfree(vq->indirect); 244 vq->indirect = NULL; 245 kfree(vq->log); 246 vq->log = NULL; 247 kfree(vq->heads); 248 vq->heads = NULL; 249 } 250 251 /* Helper to allocate iovec buffers for all vqs. */ 252 static long vhost_dev_alloc_iovecs(struct vhost_dev *dev) 253 { 254 int i; 255 256 for (i = 0; i < dev->nvqs; ++i) { 257 dev->vqs[i]->indirect = kmalloc(sizeof *dev->vqs[i]->indirect * 258 UIO_MAXIOV, GFP_KERNEL); 259 dev->vqs[i]->log = kmalloc(sizeof *dev->vqs[i]->log * UIO_MAXIOV, 260 GFP_KERNEL); 261 dev->vqs[i]->heads = kmalloc(sizeof *dev->vqs[i]->heads * 262 UIO_MAXIOV, GFP_KERNEL); 263 if (!dev->vqs[i]->indirect || !dev->vqs[i]->log || 264 !dev->vqs[i]->heads) 265 goto err_nomem; 266 } 267 return 0; 268 269 err_nomem: 270 for (; i >= 0; --i) 271 vhost_vq_free_iovecs(dev->vqs[i]); 272 return -ENOMEM; 273 } 274 275 static void vhost_dev_free_iovecs(struct vhost_dev *dev) 276 { 277 int i; 278 279 for (i = 0; i < dev->nvqs; ++i) 280 vhost_vq_free_iovecs(dev->vqs[i]); 281 } 282 283 long vhost_dev_init(struct vhost_dev *dev, 284 struct vhost_virtqueue **vqs, int nvqs) 285 { 286 int i; 287 288 dev->vqs = vqs; 289 dev->nvqs = nvqs; 290 mutex_init(&dev->mutex); 291 dev->log_ctx = NULL; 292 dev->log_file = NULL; 293 dev->memory = NULL; 294 dev->mm = NULL; 295 spin_lock_init(&dev->work_lock); 296 INIT_LIST_HEAD(&dev->work_list); 297 dev->worker = NULL; 298 299 for (i = 0; i < dev->nvqs; ++i) { 300 dev->vqs[i]->log = NULL; 301 dev->vqs[i]->indirect = NULL; 302 dev->vqs[i]->heads = NULL; 303 dev->vqs[i]->dev = dev; 304 mutex_init(&dev->vqs[i]->mutex); 305 vhost_vq_reset(dev, dev->vqs[i]); 306 if (dev->vqs[i]->handle_kick) 307 vhost_poll_init(&dev->vqs[i]->poll, 308 dev->vqs[i]->handle_kick, POLLIN, dev); 309 } 310 311 return 0; 312 } 313 314 /* Caller should have device mutex */ 315 long vhost_dev_check_owner(struct vhost_dev *dev) 316 { 317 /* Are you the owner? If not, I don't think you mean to do that */ 318 return dev->mm == current->mm ? 0 : -EPERM; 319 } 320 321 struct vhost_attach_cgroups_struct { 322 struct vhost_work work; 323 struct task_struct *owner; 324 int ret; 325 }; 326 327 static void vhost_attach_cgroups_work(struct vhost_work *work) 328 { 329 struct vhost_attach_cgroups_struct *s; 330 331 s = container_of(work, struct vhost_attach_cgroups_struct, work); 332 s->ret = cgroup_attach_task_all(s->owner, current); 333 } 334 335 static int vhost_attach_cgroups(struct vhost_dev *dev) 336 { 337 struct vhost_attach_cgroups_struct attach; 338 339 attach.owner = current; 340 vhost_work_init(&attach.work, vhost_attach_cgroups_work); 341 vhost_work_queue(dev, &attach.work); 342 vhost_work_flush(dev, &attach.work); 343 return attach.ret; 344 } 345 346 /* Caller should have device mutex */ 347 bool vhost_dev_has_owner(struct vhost_dev *dev) 348 { 349 return dev->mm; 350 } 351 352 /* Caller should have device mutex */ 353 long vhost_dev_set_owner(struct vhost_dev *dev) 354 { 355 struct task_struct *worker; 356 int err; 357 358 /* Is there an owner already? */ 359 if (vhost_dev_has_owner(dev)) { 360 err = -EBUSY; 361 goto err_mm; 362 } 363 364 /* No owner, become one */ 365 dev->mm = get_task_mm(current); 366 worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid); 367 if (IS_ERR(worker)) { 368 err = PTR_ERR(worker); 369 goto err_worker; 370 } 371 372 dev->worker = worker; 373 wake_up_process(worker); /* avoid contributing to loadavg */ 374 375 err = vhost_attach_cgroups(dev); 376 if (err) 377 goto err_cgroup; 378 379 err = vhost_dev_alloc_iovecs(dev); 380 if (err) 381 goto err_cgroup; 382 383 return 0; 384 err_cgroup: 385 kthread_stop(worker); 386 dev->worker = NULL; 387 err_worker: 388 if (dev->mm) 389 mmput(dev->mm); 390 dev->mm = NULL; 391 err_mm: 392 return err; 393 } 394 395 struct vhost_memory *vhost_dev_reset_owner_prepare(void) 396 { 397 return kmalloc(offsetof(struct vhost_memory, regions), GFP_KERNEL); 398 } 399 400 /* Caller should have device mutex */ 401 void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_memory *memory) 402 { 403 vhost_dev_cleanup(dev, true); 404 405 /* Restore memory to default empty mapping. */ 406 memory->nregions = 0; 407 RCU_INIT_POINTER(dev->memory, memory); 408 } 409 410 void vhost_dev_stop(struct vhost_dev *dev) 411 { 412 int i; 413 414 for (i = 0; i < dev->nvqs; ++i) { 415 if (dev->vqs[i]->kick && dev->vqs[i]->handle_kick) { 416 vhost_poll_stop(&dev->vqs[i]->poll); 417 vhost_poll_flush(&dev->vqs[i]->poll); 418 } 419 } 420 } 421 422 /* Caller should have device mutex if and only if locked is set */ 423 void vhost_dev_cleanup(struct vhost_dev *dev, bool locked) 424 { 425 int i; 426 427 for (i = 0; i < dev->nvqs; ++i) { 428 if (dev->vqs[i]->error_ctx) 429 eventfd_ctx_put(dev->vqs[i]->error_ctx); 430 if (dev->vqs[i]->error) 431 fput(dev->vqs[i]->error); 432 if (dev->vqs[i]->kick) 433 fput(dev->vqs[i]->kick); 434 if (dev->vqs[i]->call_ctx) 435 eventfd_ctx_put(dev->vqs[i]->call_ctx); 436 if (dev->vqs[i]->call) 437 fput(dev->vqs[i]->call); 438 vhost_vq_reset(dev, dev->vqs[i]); 439 } 440 vhost_dev_free_iovecs(dev); 441 if (dev->log_ctx) 442 eventfd_ctx_put(dev->log_ctx); 443 dev->log_ctx = NULL; 444 if (dev->log_file) 445 fput(dev->log_file); 446 dev->log_file = NULL; 447 /* No one will access memory at this point */ 448 kfree(rcu_dereference_protected(dev->memory, 449 locked == 450 lockdep_is_held(&dev->mutex))); 451 RCU_INIT_POINTER(dev->memory, NULL); 452 WARN_ON(!list_empty(&dev->work_list)); 453 if (dev->worker) { 454 kthread_stop(dev->worker); 455 dev->worker = NULL; 456 } 457 if (dev->mm) 458 mmput(dev->mm); 459 dev->mm = NULL; 460 } 461 462 static int log_access_ok(void __user *log_base, u64 addr, unsigned long sz) 463 { 464 u64 a = addr / VHOST_PAGE_SIZE / 8; 465 466 /* Make sure 64 bit math will not overflow. */ 467 if (a > ULONG_MAX - (unsigned long)log_base || 468 a + (unsigned long)log_base > ULONG_MAX) 469 return 0; 470 471 return access_ok(VERIFY_WRITE, log_base + a, 472 (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8); 473 } 474 475 /* Caller should have vq mutex and device mutex. */ 476 static int vq_memory_access_ok(void __user *log_base, struct vhost_memory *mem, 477 int log_all) 478 { 479 int i; 480 481 if (!mem) 482 return 0; 483 484 for (i = 0; i < mem->nregions; ++i) { 485 struct vhost_memory_region *m = mem->regions + i; 486 unsigned long a = m->userspace_addr; 487 if (m->memory_size > ULONG_MAX) 488 return 0; 489 else if (!access_ok(VERIFY_WRITE, (void __user *)a, 490 m->memory_size)) 491 return 0; 492 else if (log_all && !log_access_ok(log_base, 493 m->guest_phys_addr, 494 m->memory_size)) 495 return 0; 496 } 497 return 1; 498 } 499 500 /* Can we switch to this memory table? */ 501 /* Caller should have device mutex but not vq mutex */ 502 static int memory_access_ok(struct vhost_dev *d, struct vhost_memory *mem, 503 int log_all) 504 { 505 int i; 506 507 for (i = 0; i < d->nvqs; ++i) { 508 int ok; 509 mutex_lock(&d->vqs[i]->mutex); 510 /* If ring is inactive, will check when it's enabled. */ 511 if (d->vqs[i]->private_data) 512 ok = vq_memory_access_ok(d->vqs[i]->log_base, mem, 513 log_all); 514 else 515 ok = 1; 516 mutex_unlock(&d->vqs[i]->mutex); 517 if (!ok) 518 return 0; 519 } 520 return 1; 521 } 522 523 static int vq_access_ok(struct vhost_dev *d, unsigned int num, 524 struct vring_desc __user *desc, 525 struct vring_avail __user *avail, 526 struct vring_used __user *used) 527 { 528 size_t s = vhost_has_feature(d, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0; 529 return access_ok(VERIFY_READ, desc, num * sizeof *desc) && 530 access_ok(VERIFY_READ, avail, 531 sizeof *avail + num * sizeof *avail->ring + s) && 532 access_ok(VERIFY_WRITE, used, 533 sizeof *used + num * sizeof *used->ring + s); 534 } 535 536 /* Can we log writes? */ 537 /* Caller should have device mutex but not vq mutex */ 538 int vhost_log_access_ok(struct vhost_dev *dev) 539 { 540 struct vhost_memory *mp; 541 542 mp = rcu_dereference_protected(dev->memory, 543 lockdep_is_held(&dev->mutex)); 544 return memory_access_ok(dev, mp, 1); 545 } 546 547 /* Verify access for write logging. */ 548 /* Caller should have vq mutex and device mutex */ 549 static int vq_log_access_ok(struct vhost_dev *d, struct vhost_virtqueue *vq, 550 void __user *log_base) 551 { 552 struct vhost_memory *mp; 553 size_t s = vhost_has_feature(d, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0; 554 555 mp = rcu_dereference_protected(vq->dev->memory, 556 lockdep_is_held(&vq->mutex)); 557 return vq_memory_access_ok(log_base, mp, 558 vhost_has_feature(vq->dev, VHOST_F_LOG_ALL)) && 559 (!vq->log_used || log_access_ok(log_base, vq->log_addr, 560 sizeof *vq->used + 561 vq->num * sizeof *vq->used->ring + s)); 562 } 563 564 /* Can we start vq? */ 565 /* Caller should have vq mutex and device mutex */ 566 int vhost_vq_access_ok(struct vhost_virtqueue *vq) 567 { 568 return vq_access_ok(vq->dev, vq->num, vq->desc, vq->avail, vq->used) && 569 vq_log_access_ok(vq->dev, vq, vq->log_base); 570 } 571 572 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m) 573 { 574 struct vhost_memory mem, *newmem, *oldmem; 575 unsigned long size = offsetof(struct vhost_memory, regions); 576 577 if (copy_from_user(&mem, m, size)) 578 return -EFAULT; 579 if (mem.padding) 580 return -EOPNOTSUPP; 581 if (mem.nregions > VHOST_MEMORY_MAX_NREGIONS) 582 return -E2BIG; 583 newmem = kmalloc(size + mem.nregions * sizeof *m->regions, GFP_KERNEL); 584 if (!newmem) 585 return -ENOMEM; 586 587 memcpy(newmem, &mem, size); 588 if (copy_from_user(newmem->regions, m->regions, 589 mem.nregions * sizeof *m->regions)) { 590 kfree(newmem); 591 return -EFAULT; 592 } 593 594 if (!memory_access_ok(d, newmem, 595 vhost_has_feature(d, VHOST_F_LOG_ALL))) { 596 kfree(newmem); 597 return -EFAULT; 598 } 599 oldmem = rcu_dereference_protected(d->memory, 600 lockdep_is_held(&d->mutex)); 601 rcu_assign_pointer(d->memory, newmem); 602 synchronize_rcu(); 603 kfree(oldmem); 604 return 0; 605 } 606 607 long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp) 608 { 609 struct file *eventfp, *filep = NULL; 610 bool pollstart = false, pollstop = false; 611 struct eventfd_ctx *ctx = NULL; 612 u32 __user *idxp = argp; 613 struct vhost_virtqueue *vq; 614 struct vhost_vring_state s; 615 struct vhost_vring_file f; 616 struct vhost_vring_addr a; 617 u32 idx; 618 long r; 619 620 r = get_user(idx, idxp); 621 if (r < 0) 622 return r; 623 if (idx >= d->nvqs) 624 return -ENOBUFS; 625 626 vq = d->vqs[idx]; 627 628 mutex_lock(&vq->mutex); 629 630 switch (ioctl) { 631 case VHOST_SET_VRING_NUM: 632 /* Resizing ring with an active backend? 633 * You don't want to do that. */ 634 if (vq->private_data) { 635 r = -EBUSY; 636 break; 637 } 638 if (copy_from_user(&s, argp, sizeof s)) { 639 r = -EFAULT; 640 break; 641 } 642 if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) { 643 r = -EINVAL; 644 break; 645 } 646 vq->num = s.num; 647 break; 648 case VHOST_SET_VRING_BASE: 649 /* Moving base with an active backend? 650 * You don't want to do that. */ 651 if (vq->private_data) { 652 r = -EBUSY; 653 break; 654 } 655 if (copy_from_user(&s, argp, sizeof s)) { 656 r = -EFAULT; 657 break; 658 } 659 if (s.num > 0xffff) { 660 r = -EINVAL; 661 break; 662 } 663 vq->last_avail_idx = s.num; 664 /* Forget the cached index value. */ 665 vq->avail_idx = vq->last_avail_idx; 666 break; 667 case VHOST_GET_VRING_BASE: 668 s.index = idx; 669 s.num = vq->last_avail_idx; 670 if (copy_to_user(argp, &s, sizeof s)) 671 r = -EFAULT; 672 break; 673 case VHOST_SET_VRING_ADDR: 674 if (copy_from_user(&a, argp, sizeof a)) { 675 r = -EFAULT; 676 break; 677 } 678 if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) { 679 r = -EOPNOTSUPP; 680 break; 681 } 682 /* For 32bit, verify that the top 32bits of the user 683 data are set to zero. */ 684 if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr || 685 (u64)(unsigned long)a.used_user_addr != a.used_user_addr || 686 (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) { 687 r = -EFAULT; 688 break; 689 } 690 if ((a.avail_user_addr & (sizeof *vq->avail->ring - 1)) || 691 (a.used_user_addr & (sizeof *vq->used->ring - 1)) || 692 (a.log_guest_addr & (sizeof *vq->used->ring - 1))) { 693 r = -EINVAL; 694 break; 695 } 696 697 /* We only verify access here if backend is configured. 698 * If it is not, we don't as size might not have been setup. 699 * We will verify when backend is configured. */ 700 if (vq->private_data) { 701 if (!vq_access_ok(d, vq->num, 702 (void __user *)(unsigned long)a.desc_user_addr, 703 (void __user *)(unsigned long)a.avail_user_addr, 704 (void __user *)(unsigned long)a.used_user_addr)) { 705 r = -EINVAL; 706 break; 707 } 708 709 /* Also validate log access for used ring if enabled. */ 710 if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) && 711 !log_access_ok(vq->log_base, a.log_guest_addr, 712 sizeof *vq->used + 713 vq->num * sizeof *vq->used->ring)) { 714 r = -EINVAL; 715 break; 716 } 717 } 718 719 vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG)); 720 vq->desc = (void __user *)(unsigned long)a.desc_user_addr; 721 vq->avail = (void __user *)(unsigned long)a.avail_user_addr; 722 vq->log_addr = a.log_guest_addr; 723 vq->used = (void __user *)(unsigned long)a.used_user_addr; 724 break; 725 case VHOST_SET_VRING_KICK: 726 if (copy_from_user(&f, argp, sizeof f)) { 727 r = -EFAULT; 728 break; 729 } 730 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); 731 if (IS_ERR(eventfp)) { 732 r = PTR_ERR(eventfp); 733 break; 734 } 735 if (eventfp != vq->kick) { 736 pollstop = (filep = vq->kick) != NULL; 737 pollstart = (vq->kick = eventfp) != NULL; 738 } else 739 filep = eventfp; 740 break; 741 case VHOST_SET_VRING_CALL: 742 if (copy_from_user(&f, argp, sizeof f)) { 743 r = -EFAULT; 744 break; 745 } 746 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); 747 if (IS_ERR(eventfp)) { 748 r = PTR_ERR(eventfp); 749 break; 750 } 751 if (eventfp != vq->call) { 752 filep = vq->call; 753 ctx = vq->call_ctx; 754 vq->call = eventfp; 755 vq->call_ctx = eventfp ? 756 eventfd_ctx_fileget(eventfp) : NULL; 757 } else 758 filep = eventfp; 759 break; 760 case VHOST_SET_VRING_ERR: 761 if (copy_from_user(&f, argp, sizeof f)) { 762 r = -EFAULT; 763 break; 764 } 765 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); 766 if (IS_ERR(eventfp)) { 767 r = PTR_ERR(eventfp); 768 break; 769 } 770 if (eventfp != vq->error) { 771 filep = vq->error; 772 vq->error = eventfp; 773 ctx = vq->error_ctx; 774 vq->error_ctx = eventfp ? 775 eventfd_ctx_fileget(eventfp) : NULL; 776 } else 777 filep = eventfp; 778 break; 779 default: 780 r = -ENOIOCTLCMD; 781 } 782 783 if (pollstop && vq->handle_kick) 784 vhost_poll_stop(&vq->poll); 785 786 if (ctx) 787 eventfd_ctx_put(ctx); 788 if (filep) 789 fput(filep); 790 791 if (pollstart && vq->handle_kick) 792 r = vhost_poll_start(&vq->poll, vq->kick); 793 794 mutex_unlock(&vq->mutex); 795 796 if (pollstop && vq->handle_kick) 797 vhost_poll_flush(&vq->poll); 798 return r; 799 } 800 801 /* Caller must have device mutex */ 802 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp) 803 { 804 struct file *eventfp, *filep = NULL; 805 struct eventfd_ctx *ctx = NULL; 806 u64 p; 807 long r; 808 int i, fd; 809 810 /* If you are not the owner, you can become one */ 811 if (ioctl == VHOST_SET_OWNER) { 812 r = vhost_dev_set_owner(d); 813 goto done; 814 } 815 816 /* You must be the owner to do anything else */ 817 r = vhost_dev_check_owner(d); 818 if (r) 819 goto done; 820 821 switch (ioctl) { 822 case VHOST_SET_MEM_TABLE: 823 r = vhost_set_memory(d, argp); 824 break; 825 case VHOST_SET_LOG_BASE: 826 if (copy_from_user(&p, argp, sizeof p)) { 827 r = -EFAULT; 828 break; 829 } 830 if ((u64)(unsigned long)p != p) { 831 r = -EFAULT; 832 break; 833 } 834 for (i = 0; i < d->nvqs; ++i) { 835 struct vhost_virtqueue *vq; 836 void __user *base = (void __user *)(unsigned long)p; 837 vq = d->vqs[i]; 838 mutex_lock(&vq->mutex); 839 /* If ring is inactive, will check when it's enabled. */ 840 if (vq->private_data && !vq_log_access_ok(d, vq, base)) 841 r = -EFAULT; 842 else 843 vq->log_base = base; 844 mutex_unlock(&vq->mutex); 845 } 846 break; 847 case VHOST_SET_LOG_FD: 848 r = get_user(fd, (int __user *)argp); 849 if (r < 0) 850 break; 851 eventfp = fd == -1 ? NULL : eventfd_fget(fd); 852 if (IS_ERR(eventfp)) { 853 r = PTR_ERR(eventfp); 854 break; 855 } 856 if (eventfp != d->log_file) { 857 filep = d->log_file; 858 ctx = d->log_ctx; 859 d->log_ctx = eventfp ? 860 eventfd_ctx_fileget(eventfp) : NULL; 861 } else 862 filep = eventfp; 863 for (i = 0; i < d->nvqs; ++i) { 864 mutex_lock(&d->vqs[i]->mutex); 865 d->vqs[i]->log_ctx = d->log_ctx; 866 mutex_unlock(&d->vqs[i]->mutex); 867 } 868 if (ctx) 869 eventfd_ctx_put(ctx); 870 if (filep) 871 fput(filep); 872 break; 873 default: 874 r = -ENOIOCTLCMD; 875 break; 876 } 877 done: 878 return r; 879 } 880 881 static const struct vhost_memory_region *find_region(struct vhost_memory *mem, 882 __u64 addr, __u32 len) 883 { 884 struct vhost_memory_region *reg; 885 int i; 886 887 /* linear search is not brilliant, but we really have on the order of 6 888 * regions in practice */ 889 for (i = 0; i < mem->nregions; ++i) { 890 reg = mem->regions + i; 891 if (reg->guest_phys_addr <= addr && 892 reg->guest_phys_addr + reg->memory_size - 1 >= addr) 893 return reg; 894 } 895 return NULL; 896 } 897 898 /* TODO: This is really inefficient. We need something like get_user() 899 * (instruction directly accesses the data, with an exception table entry 900 * returning -EFAULT). See Documentation/x86/exception-tables.txt. 901 */ 902 static int set_bit_to_user(int nr, void __user *addr) 903 { 904 unsigned long log = (unsigned long)addr; 905 struct page *page; 906 void *base; 907 int bit = nr + (log % PAGE_SIZE) * 8; 908 int r; 909 910 r = get_user_pages_fast(log, 1, 1, &page); 911 if (r < 0) 912 return r; 913 BUG_ON(r != 1); 914 base = kmap_atomic(page); 915 set_bit(bit, base); 916 kunmap_atomic(base); 917 set_page_dirty_lock(page); 918 put_page(page); 919 return 0; 920 } 921 922 static int log_write(void __user *log_base, 923 u64 write_address, u64 write_length) 924 { 925 u64 write_page = write_address / VHOST_PAGE_SIZE; 926 int r; 927 928 if (!write_length) 929 return 0; 930 write_length += write_address % VHOST_PAGE_SIZE; 931 for (;;) { 932 u64 base = (u64)(unsigned long)log_base; 933 u64 log = base + write_page / 8; 934 int bit = write_page % 8; 935 if ((u64)(unsigned long)log != log) 936 return -EFAULT; 937 r = set_bit_to_user(bit, (void __user *)(unsigned long)log); 938 if (r < 0) 939 return r; 940 if (write_length <= VHOST_PAGE_SIZE) 941 break; 942 write_length -= VHOST_PAGE_SIZE; 943 write_page += 1; 944 } 945 return r; 946 } 947 948 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log, 949 unsigned int log_num, u64 len) 950 { 951 int i, r; 952 953 /* Make sure data written is seen before log. */ 954 smp_wmb(); 955 for (i = 0; i < log_num; ++i) { 956 u64 l = min(log[i].len, len); 957 r = log_write(vq->log_base, log[i].addr, l); 958 if (r < 0) 959 return r; 960 len -= l; 961 if (!len) { 962 if (vq->log_ctx) 963 eventfd_signal(vq->log_ctx, 1); 964 return 0; 965 } 966 } 967 /* Length written exceeds what we have stored. This is a bug. */ 968 BUG(); 969 return 0; 970 } 971 972 static int vhost_update_used_flags(struct vhost_virtqueue *vq) 973 { 974 void __user *used; 975 if (__put_user(vq->used_flags, &vq->used->flags) < 0) 976 return -EFAULT; 977 if (unlikely(vq->log_used)) { 978 /* Make sure the flag is seen before log. */ 979 smp_wmb(); 980 /* Log used flag write. */ 981 used = &vq->used->flags; 982 log_write(vq->log_base, vq->log_addr + 983 (used - (void __user *)vq->used), 984 sizeof vq->used->flags); 985 if (vq->log_ctx) 986 eventfd_signal(vq->log_ctx, 1); 987 } 988 return 0; 989 } 990 991 static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event) 992 { 993 if (__put_user(vq->avail_idx, vhost_avail_event(vq))) 994 return -EFAULT; 995 if (unlikely(vq->log_used)) { 996 void __user *used; 997 /* Make sure the event is seen before log. */ 998 smp_wmb(); 999 /* Log avail event write */ 1000 used = vhost_avail_event(vq); 1001 log_write(vq->log_base, vq->log_addr + 1002 (used - (void __user *)vq->used), 1003 sizeof *vhost_avail_event(vq)); 1004 if (vq->log_ctx) 1005 eventfd_signal(vq->log_ctx, 1); 1006 } 1007 return 0; 1008 } 1009 1010 int vhost_init_used(struct vhost_virtqueue *vq) 1011 { 1012 int r; 1013 if (!vq->private_data) 1014 return 0; 1015 1016 r = vhost_update_used_flags(vq); 1017 if (r) 1018 return r; 1019 vq->signalled_used_valid = false; 1020 return get_user(vq->last_used_idx, &vq->used->idx); 1021 } 1022 1023 static int translate_desc(struct vhost_dev *dev, u64 addr, u32 len, 1024 struct iovec iov[], int iov_size) 1025 { 1026 const struct vhost_memory_region *reg; 1027 struct vhost_memory *mem; 1028 struct iovec *_iov; 1029 u64 s = 0; 1030 int ret = 0; 1031 1032 rcu_read_lock(); 1033 1034 mem = rcu_dereference(dev->memory); 1035 while ((u64)len > s) { 1036 u64 size; 1037 if (unlikely(ret >= iov_size)) { 1038 ret = -ENOBUFS; 1039 break; 1040 } 1041 reg = find_region(mem, addr, len); 1042 if (unlikely(!reg)) { 1043 ret = -EFAULT; 1044 break; 1045 } 1046 _iov = iov + ret; 1047 size = reg->memory_size - addr + reg->guest_phys_addr; 1048 _iov->iov_len = min((u64)len - s, size); 1049 _iov->iov_base = (void __user *)(unsigned long) 1050 (reg->userspace_addr + addr - reg->guest_phys_addr); 1051 s += size; 1052 addr += size; 1053 ++ret; 1054 } 1055 1056 rcu_read_unlock(); 1057 return ret; 1058 } 1059 1060 /* Each buffer in the virtqueues is actually a chain of descriptors. This 1061 * function returns the next descriptor in the chain, 1062 * or -1U if we're at the end. */ 1063 static unsigned next_desc(struct vring_desc *desc) 1064 { 1065 unsigned int next; 1066 1067 /* If this descriptor says it doesn't chain, we're done. */ 1068 if (!(desc->flags & VRING_DESC_F_NEXT)) 1069 return -1U; 1070 1071 /* Check they're not leading us off end of descriptors. */ 1072 next = desc->next; 1073 /* Make sure compiler knows to grab that: we don't want it changing! */ 1074 /* We will use the result as an index in an array, so most 1075 * architectures only need a compiler barrier here. */ 1076 read_barrier_depends(); 1077 1078 return next; 1079 } 1080 1081 static int get_indirect(struct vhost_dev *dev, struct vhost_virtqueue *vq, 1082 struct iovec iov[], unsigned int iov_size, 1083 unsigned int *out_num, unsigned int *in_num, 1084 struct vhost_log *log, unsigned int *log_num, 1085 struct vring_desc *indirect) 1086 { 1087 struct vring_desc desc; 1088 unsigned int i = 0, count, found = 0; 1089 int ret; 1090 1091 /* Sanity check */ 1092 if (unlikely(indirect->len % sizeof desc)) { 1093 vq_err(vq, "Invalid length in indirect descriptor: " 1094 "len 0x%llx not multiple of 0x%zx\n", 1095 (unsigned long long)indirect->len, 1096 sizeof desc); 1097 return -EINVAL; 1098 } 1099 1100 ret = translate_desc(dev, indirect->addr, indirect->len, vq->indirect, 1101 UIO_MAXIOV); 1102 if (unlikely(ret < 0)) { 1103 vq_err(vq, "Translation failure %d in indirect.\n", ret); 1104 return ret; 1105 } 1106 1107 /* We will use the result as an address to read from, so most 1108 * architectures only need a compiler barrier here. */ 1109 read_barrier_depends(); 1110 1111 count = indirect->len / sizeof desc; 1112 /* Buffers are chained via a 16 bit next field, so 1113 * we can have at most 2^16 of these. */ 1114 if (unlikely(count > USHRT_MAX + 1)) { 1115 vq_err(vq, "Indirect buffer length too big: %d\n", 1116 indirect->len); 1117 return -E2BIG; 1118 } 1119 1120 do { 1121 unsigned iov_count = *in_num + *out_num; 1122 if (unlikely(++found > count)) { 1123 vq_err(vq, "Loop detected: last one at %u " 1124 "indirect size %u\n", 1125 i, count); 1126 return -EINVAL; 1127 } 1128 if (unlikely(memcpy_fromiovec((unsigned char *)&desc, 1129 vq->indirect, sizeof desc))) { 1130 vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n", 1131 i, (size_t)indirect->addr + i * sizeof desc); 1132 return -EINVAL; 1133 } 1134 if (unlikely(desc.flags & VRING_DESC_F_INDIRECT)) { 1135 vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n", 1136 i, (size_t)indirect->addr + i * sizeof desc); 1137 return -EINVAL; 1138 } 1139 1140 ret = translate_desc(dev, desc.addr, desc.len, iov + iov_count, 1141 iov_size - iov_count); 1142 if (unlikely(ret < 0)) { 1143 vq_err(vq, "Translation failure %d indirect idx %d\n", 1144 ret, i); 1145 return ret; 1146 } 1147 /* If this is an input descriptor, increment that count. */ 1148 if (desc.flags & VRING_DESC_F_WRITE) { 1149 *in_num += ret; 1150 if (unlikely(log)) { 1151 log[*log_num].addr = desc.addr; 1152 log[*log_num].len = desc.len; 1153 ++*log_num; 1154 } 1155 } else { 1156 /* If it's an output descriptor, they're all supposed 1157 * to come before any input descriptors. */ 1158 if (unlikely(*in_num)) { 1159 vq_err(vq, "Indirect descriptor " 1160 "has out after in: idx %d\n", i); 1161 return -EINVAL; 1162 } 1163 *out_num += ret; 1164 } 1165 } while ((i = next_desc(&desc)) != -1); 1166 return 0; 1167 } 1168 1169 /* This looks in the virtqueue and for the first available buffer, and converts 1170 * it to an iovec for convenient access. Since descriptors consist of some 1171 * number of output then some number of input descriptors, it's actually two 1172 * iovecs, but we pack them into one and note how many of each there were. 1173 * 1174 * This function returns the descriptor number found, or vq->num (which is 1175 * never a valid descriptor number) if none was found. A negative code is 1176 * returned on error. */ 1177 int vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq, 1178 struct iovec iov[], unsigned int iov_size, 1179 unsigned int *out_num, unsigned int *in_num, 1180 struct vhost_log *log, unsigned int *log_num) 1181 { 1182 struct vring_desc desc; 1183 unsigned int i, head, found = 0; 1184 u16 last_avail_idx; 1185 int ret; 1186 1187 /* Check it isn't doing very strange things with descriptor numbers. */ 1188 last_avail_idx = vq->last_avail_idx; 1189 if (unlikely(__get_user(vq->avail_idx, &vq->avail->idx))) { 1190 vq_err(vq, "Failed to access avail idx at %p\n", 1191 &vq->avail->idx); 1192 return -EFAULT; 1193 } 1194 1195 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) { 1196 vq_err(vq, "Guest moved used index from %u to %u", 1197 last_avail_idx, vq->avail_idx); 1198 return -EFAULT; 1199 } 1200 1201 /* If there's nothing new since last we looked, return invalid. */ 1202 if (vq->avail_idx == last_avail_idx) 1203 return vq->num; 1204 1205 /* Only get avail ring entries after they have been exposed by guest. */ 1206 smp_rmb(); 1207 1208 /* Grab the next descriptor number they're advertising, and increment 1209 * the index we've seen. */ 1210 if (unlikely(__get_user(head, 1211 &vq->avail->ring[last_avail_idx % vq->num]))) { 1212 vq_err(vq, "Failed to read head: idx %d address %p\n", 1213 last_avail_idx, 1214 &vq->avail->ring[last_avail_idx % vq->num]); 1215 return -EFAULT; 1216 } 1217 1218 /* If their number is silly, that's an error. */ 1219 if (unlikely(head >= vq->num)) { 1220 vq_err(vq, "Guest says index %u > %u is available", 1221 head, vq->num); 1222 return -EINVAL; 1223 } 1224 1225 /* When we start there are none of either input nor output. */ 1226 *out_num = *in_num = 0; 1227 if (unlikely(log)) 1228 *log_num = 0; 1229 1230 i = head; 1231 do { 1232 unsigned iov_count = *in_num + *out_num; 1233 if (unlikely(i >= vq->num)) { 1234 vq_err(vq, "Desc index is %u > %u, head = %u", 1235 i, vq->num, head); 1236 return -EINVAL; 1237 } 1238 if (unlikely(++found > vq->num)) { 1239 vq_err(vq, "Loop detected: last one at %u " 1240 "vq size %u head %u\n", 1241 i, vq->num, head); 1242 return -EINVAL; 1243 } 1244 ret = __copy_from_user(&desc, vq->desc + i, sizeof desc); 1245 if (unlikely(ret)) { 1246 vq_err(vq, "Failed to get descriptor: idx %d addr %p\n", 1247 i, vq->desc + i); 1248 return -EFAULT; 1249 } 1250 if (desc.flags & VRING_DESC_F_INDIRECT) { 1251 ret = get_indirect(dev, vq, iov, iov_size, 1252 out_num, in_num, 1253 log, log_num, &desc); 1254 if (unlikely(ret < 0)) { 1255 vq_err(vq, "Failure detected " 1256 "in indirect descriptor at idx %d\n", i); 1257 return ret; 1258 } 1259 continue; 1260 } 1261 1262 ret = translate_desc(dev, desc.addr, desc.len, iov + iov_count, 1263 iov_size - iov_count); 1264 if (unlikely(ret < 0)) { 1265 vq_err(vq, "Translation failure %d descriptor idx %d\n", 1266 ret, i); 1267 return ret; 1268 } 1269 if (desc.flags & VRING_DESC_F_WRITE) { 1270 /* If this is an input descriptor, 1271 * increment that count. */ 1272 *in_num += ret; 1273 if (unlikely(log)) { 1274 log[*log_num].addr = desc.addr; 1275 log[*log_num].len = desc.len; 1276 ++*log_num; 1277 } 1278 } else { 1279 /* If it's an output descriptor, they're all supposed 1280 * to come before any input descriptors. */ 1281 if (unlikely(*in_num)) { 1282 vq_err(vq, "Descriptor has out after in: " 1283 "idx %d\n", i); 1284 return -EINVAL; 1285 } 1286 *out_num += ret; 1287 } 1288 } while ((i = next_desc(&desc)) != -1); 1289 1290 /* On success, increment avail index. */ 1291 vq->last_avail_idx++; 1292 1293 /* Assume notifications from guest are disabled at this point, 1294 * if they aren't we would need to update avail_event index. */ 1295 BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY)); 1296 return head; 1297 } 1298 1299 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */ 1300 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n) 1301 { 1302 vq->last_avail_idx -= n; 1303 } 1304 1305 /* After we've used one of their buffers, we tell them about it. We'll then 1306 * want to notify the guest, using eventfd. */ 1307 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len) 1308 { 1309 struct vring_used_elem __user *used; 1310 1311 /* The virtqueue contains a ring of used buffers. Get a pointer to the 1312 * next entry in that used ring. */ 1313 used = &vq->used->ring[vq->last_used_idx % vq->num]; 1314 if (__put_user(head, &used->id)) { 1315 vq_err(vq, "Failed to write used id"); 1316 return -EFAULT; 1317 } 1318 if (__put_user(len, &used->len)) { 1319 vq_err(vq, "Failed to write used len"); 1320 return -EFAULT; 1321 } 1322 /* Make sure buffer is written before we update index. */ 1323 smp_wmb(); 1324 if (__put_user(vq->last_used_idx + 1, &vq->used->idx)) { 1325 vq_err(vq, "Failed to increment used idx"); 1326 return -EFAULT; 1327 } 1328 if (unlikely(vq->log_used)) { 1329 /* Make sure data is seen before log. */ 1330 smp_wmb(); 1331 /* Log used ring entry write. */ 1332 log_write(vq->log_base, 1333 vq->log_addr + 1334 ((void __user *)used - (void __user *)vq->used), 1335 sizeof *used); 1336 /* Log used index update. */ 1337 log_write(vq->log_base, 1338 vq->log_addr + offsetof(struct vring_used, idx), 1339 sizeof vq->used->idx); 1340 if (vq->log_ctx) 1341 eventfd_signal(vq->log_ctx, 1); 1342 } 1343 vq->last_used_idx++; 1344 /* If the driver never bothers to signal in a very long while, 1345 * used index might wrap around. If that happens, invalidate 1346 * signalled_used index we stored. TODO: make sure driver 1347 * signals at least once in 2^16 and remove this. */ 1348 if (unlikely(vq->last_used_idx == vq->signalled_used)) 1349 vq->signalled_used_valid = false; 1350 return 0; 1351 } 1352 1353 static int __vhost_add_used_n(struct vhost_virtqueue *vq, 1354 struct vring_used_elem *heads, 1355 unsigned count) 1356 { 1357 struct vring_used_elem __user *used; 1358 u16 old, new; 1359 int start; 1360 1361 start = vq->last_used_idx % vq->num; 1362 used = vq->used->ring + start; 1363 if (__copy_to_user(used, heads, count * sizeof *used)) { 1364 vq_err(vq, "Failed to write used"); 1365 return -EFAULT; 1366 } 1367 if (unlikely(vq->log_used)) { 1368 /* Make sure data is seen before log. */ 1369 smp_wmb(); 1370 /* Log used ring entry write. */ 1371 log_write(vq->log_base, 1372 vq->log_addr + 1373 ((void __user *)used - (void __user *)vq->used), 1374 count * sizeof *used); 1375 } 1376 old = vq->last_used_idx; 1377 new = (vq->last_used_idx += count); 1378 /* If the driver never bothers to signal in a very long while, 1379 * used index might wrap around. If that happens, invalidate 1380 * signalled_used index we stored. TODO: make sure driver 1381 * signals at least once in 2^16 and remove this. */ 1382 if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old))) 1383 vq->signalled_used_valid = false; 1384 return 0; 1385 } 1386 1387 /* After we've used one of their buffers, we tell them about it. We'll then 1388 * want to notify the guest, using eventfd. */ 1389 int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads, 1390 unsigned count) 1391 { 1392 int start, n, r; 1393 1394 start = vq->last_used_idx % vq->num; 1395 n = vq->num - start; 1396 if (n < count) { 1397 r = __vhost_add_used_n(vq, heads, n); 1398 if (r < 0) 1399 return r; 1400 heads += n; 1401 count -= n; 1402 } 1403 r = __vhost_add_used_n(vq, heads, count); 1404 1405 /* Make sure buffer is written before we update index. */ 1406 smp_wmb(); 1407 if (put_user(vq->last_used_idx, &vq->used->idx)) { 1408 vq_err(vq, "Failed to increment used idx"); 1409 return -EFAULT; 1410 } 1411 if (unlikely(vq->log_used)) { 1412 /* Log used index update. */ 1413 log_write(vq->log_base, 1414 vq->log_addr + offsetof(struct vring_used, idx), 1415 sizeof vq->used->idx); 1416 if (vq->log_ctx) 1417 eventfd_signal(vq->log_ctx, 1); 1418 } 1419 return r; 1420 } 1421 1422 static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) 1423 { 1424 __u16 old, new, event; 1425 bool v; 1426 /* Flush out used index updates. This is paired 1427 * with the barrier that the Guest executes when enabling 1428 * interrupts. */ 1429 smp_mb(); 1430 1431 if (vhost_has_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY) && 1432 unlikely(vq->avail_idx == vq->last_avail_idx)) 1433 return true; 1434 1435 if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) { 1436 __u16 flags; 1437 if (__get_user(flags, &vq->avail->flags)) { 1438 vq_err(vq, "Failed to get flags"); 1439 return true; 1440 } 1441 return !(flags & VRING_AVAIL_F_NO_INTERRUPT); 1442 } 1443 old = vq->signalled_used; 1444 v = vq->signalled_used_valid; 1445 new = vq->signalled_used = vq->last_used_idx; 1446 vq->signalled_used_valid = true; 1447 1448 if (unlikely(!v)) 1449 return true; 1450 1451 if (get_user(event, vhost_used_event(vq))) { 1452 vq_err(vq, "Failed to get used event idx"); 1453 return true; 1454 } 1455 return vring_need_event(event, new, old); 1456 } 1457 1458 /* This actually signals the guest, using eventfd. */ 1459 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq) 1460 { 1461 /* Signal the Guest tell them we used something up. */ 1462 if (vq->call_ctx && vhost_notify(dev, vq)) 1463 eventfd_signal(vq->call_ctx, 1); 1464 } 1465 1466 /* And here's the combo meal deal. Supersize me! */ 1467 void vhost_add_used_and_signal(struct vhost_dev *dev, 1468 struct vhost_virtqueue *vq, 1469 unsigned int head, int len) 1470 { 1471 vhost_add_used(vq, head, len); 1472 vhost_signal(dev, vq); 1473 } 1474 1475 /* multi-buffer version of vhost_add_used_and_signal */ 1476 void vhost_add_used_and_signal_n(struct vhost_dev *dev, 1477 struct vhost_virtqueue *vq, 1478 struct vring_used_elem *heads, unsigned count) 1479 { 1480 vhost_add_used_n(vq, heads, count); 1481 vhost_signal(dev, vq); 1482 } 1483 1484 /* OK, now we need to know about added descriptors. */ 1485 bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) 1486 { 1487 u16 avail_idx; 1488 int r; 1489 1490 if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY)) 1491 return false; 1492 vq->used_flags &= ~VRING_USED_F_NO_NOTIFY; 1493 if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) { 1494 r = vhost_update_used_flags(vq); 1495 if (r) { 1496 vq_err(vq, "Failed to enable notification at %p: %d\n", 1497 &vq->used->flags, r); 1498 return false; 1499 } 1500 } else { 1501 r = vhost_update_avail_event(vq, vq->avail_idx); 1502 if (r) { 1503 vq_err(vq, "Failed to update avail event index at %p: %d\n", 1504 vhost_avail_event(vq), r); 1505 return false; 1506 } 1507 } 1508 /* They could have slipped one in as we were doing that: make 1509 * sure it's written, then check again. */ 1510 smp_mb(); 1511 r = __get_user(avail_idx, &vq->avail->idx); 1512 if (r) { 1513 vq_err(vq, "Failed to check avail idx at %p: %d\n", 1514 &vq->avail->idx, r); 1515 return false; 1516 } 1517 1518 return avail_idx != vq->avail_idx; 1519 } 1520 1521 /* We don't need to be notified again. */ 1522 void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) 1523 { 1524 int r; 1525 1526 if (vq->used_flags & VRING_USED_F_NO_NOTIFY) 1527 return; 1528 vq->used_flags |= VRING_USED_F_NO_NOTIFY; 1529 if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) { 1530 r = vhost_update_used_flags(vq); 1531 if (r) 1532 vq_err(vq, "Failed to enable notification at %p: %d\n", 1533 &vq->used->flags, r); 1534 } 1535 } 1536