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