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/virtio_net.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/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 <linux/net.h> 30 #include <linux/if_packet.h> 31 #include <linux/if_arp.h> 32 33 #include "vhost.h" 34 35 enum { 36 VHOST_MEMORY_MAX_NREGIONS = 64, 37 VHOST_MEMORY_F_LOG = 0x1, 38 }; 39 40 #define vhost_used_event(vq) ((u16 __user *)&vq->avail->ring[vq->num]) 41 #define vhost_avail_event(vq) ((u16 __user *)&vq->used->ring[vq->num]) 42 43 static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh, 44 poll_table *pt) 45 { 46 struct vhost_poll *poll; 47 48 poll = container_of(pt, struct vhost_poll, table); 49 poll->wqh = wqh; 50 add_wait_queue(wqh, &poll->wait); 51 } 52 53 static int vhost_poll_wakeup(wait_queue_t *wait, unsigned mode, int sync, 54 void *key) 55 { 56 struct vhost_poll *poll = container_of(wait, struct vhost_poll, wait); 57 58 if (!((unsigned long)key & poll->mask)) 59 return 0; 60 61 vhost_poll_queue(poll); 62 return 0; 63 } 64 65 static void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn) 66 { 67 INIT_LIST_HEAD(&work->node); 68 work->fn = fn; 69 init_waitqueue_head(&work->done); 70 work->flushing = 0; 71 work->queue_seq = work->done_seq = 0; 72 } 73 74 /* Init poll structure */ 75 void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn, 76 unsigned long mask, struct vhost_dev *dev) 77 { 78 init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup); 79 init_poll_funcptr(&poll->table, vhost_poll_func); 80 poll->mask = mask; 81 poll->dev = dev; 82 83 vhost_work_init(&poll->work, fn); 84 } 85 86 /* Start polling a file. We add ourselves to file's wait queue. The caller must 87 * keep a reference to a file until after vhost_poll_stop is called. */ 88 void vhost_poll_start(struct vhost_poll *poll, struct file *file) 89 { 90 unsigned long mask; 91 92 mask = file->f_op->poll(file, &poll->table); 93 if (mask) 94 vhost_poll_wakeup(&poll->wait, 0, 0, (void *)mask); 95 } 96 97 /* Stop polling a file. After this function returns, it becomes safe to drop the 98 * file reference. You must also flush afterwards. */ 99 void vhost_poll_stop(struct vhost_poll *poll) 100 { 101 remove_wait_queue(poll->wqh, &poll->wait); 102 } 103 104 static bool vhost_work_seq_done(struct vhost_dev *dev, struct vhost_work *work, 105 unsigned seq) 106 { 107 int left; 108 109 spin_lock_irq(&dev->work_lock); 110 left = seq - work->done_seq; 111 spin_unlock_irq(&dev->work_lock); 112 return left <= 0; 113 } 114 115 static void vhost_work_flush(struct vhost_dev *dev, struct vhost_work *work) 116 { 117 unsigned seq; 118 int flushing; 119 120 spin_lock_irq(&dev->work_lock); 121 seq = work->queue_seq; 122 work->flushing++; 123 spin_unlock_irq(&dev->work_lock); 124 wait_event(work->done, vhost_work_seq_done(dev, work, seq)); 125 spin_lock_irq(&dev->work_lock); 126 flushing = --work->flushing; 127 spin_unlock_irq(&dev->work_lock); 128 BUG_ON(flushing < 0); 129 } 130 131 /* Flush any work that has been scheduled. When calling this, don't hold any 132 * locks that are also used by the callback. */ 133 void vhost_poll_flush(struct vhost_poll *poll) 134 { 135 vhost_work_flush(poll->dev, &poll->work); 136 } 137 138 static inline void vhost_work_queue(struct vhost_dev *dev, 139 struct vhost_work *work) 140 { 141 unsigned long flags; 142 143 spin_lock_irqsave(&dev->work_lock, flags); 144 if (list_empty(&work->node)) { 145 list_add_tail(&work->node, &dev->work_list); 146 work->queue_seq++; 147 wake_up_process(dev->worker); 148 } 149 spin_unlock_irqrestore(&dev->work_lock, flags); 150 } 151 152 void vhost_poll_queue(struct vhost_poll *poll) 153 { 154 vhost_work_queue(poll->dev, &poll->work); 155 } 156 157 static void vhost_vq_reset(struct vhost_dev *dev, 158 struct vhost_virtqueue *vq) 159 { 160 vq->num = 1; 161 vq->desc = NULL; 162 vq->avail = NULL; 163 vq->used = NULL; 164 vq->last_avail_idx = 0; 165 vq->avail_idx = 0; 166 vq->last_used_idx = 0; 167 vq->signalled_used = 0; 168 vq->signalled_used_valid = false; 169 vq->used_flags = 0; 170 vq->log_used = false; 171 vq->log_addr = -1ull; 172 vq->vhost_hlen = 0; 173 vq->sock_hlen = 0; 174 vq->private_data = NULL; 175 vq->log_base = NULL; 176 vq->error_ctx = NULL; 177 vq->error = NULL; 178 vq->kick = NULL; 179 vq->call_ctx = NULL; 180 vq->call = NULL; 181 vq->log_ctx = NULL; 182 } 183 184 static int vhost_worker(void *data) 185 { 186 struct vhost_dev *dev = data; 187 struct vhost_work *work = NULL; 188 unsigned uninitialized_var(seq); 189 190 use_mm(dev->mm); 191 192 for (;;) { 193 /* mb paired w/ kthread_stop */ 194 set_current_state(TASK_INTERRUPTIBLE); 195 196 spin_lock_irq(&dev->work_lock); 197 if (work) { 198 work->done_seq = seq; 199 if (work->flushing) 200 wake_up_all(&work->done); 201 } 202 203 if (kthread_should_stop()) { 204 spin_unlock_irq(&dev->work_lock); 205 __set_current_state(TASK_RUNNING); 206 break; 207 } 208 if (!list_empty(&dev->work_list)) { 209 work = list_first_entry(&dev->work_list, 210 struct vhost_work, node); 211 list_del_init(&work->node); 212 seq = work->queue_seq; 213 } else 214 work = NULL; 215 spin_unlock_irq(&dev->work_lock); 216 217 if (work) { 218 __set_current_state(TASK_RUNNING); 219 work->fn(work); 220 } else 221 schedule(); 222 223 } 224 unuse_mm(dev->mm); 225 return 0; 226 } 227 228 /* Helper to allocate iovec buffers for all vqs. */ 229 static long vhost_dev_alloc_iovecs(struct vhost_dev *dev) 230 { 231 int i; 232 233 for (i = 0; i < dev->nvqs; ++i) { 234 dev->vqs[i].indirect = kmalloc(sizeof *dev->vqs[i].indirect * 235 UIO_MAXIOV, GFP_KERNEL); 236 dev->vqs[i].log = kmalloc(sizeof *dev->vqs[i].log * UIO_MAXIOV, 237 GFP_KERNEL); 238 dev->vqs[i].heads = kmalloc(sizeof *dev->vqs[i].heads * 239 UIO_MAXIOV, GFP_KERNEL); 240 241 if (!dev->vqs[i].indirect || !dev->vqs[i].log || 242 !dev->vqs[i].heads) 243 goto err_nomem; 244 } 245 return 0; 246 247 err_nomem: 248 for (; i >= 0; --i) { 249 kfree(dev->vqs[i].indirect); 250 kfree(dev->vqs[i].log); 251 kfree(dev->vqs[i].heads); 252 } 253 return -ENOMEM; 254 } 255 256 static void vhost_dev_free_iovecs(struct vhost_dev *dev) 257 { 258 int i; 259 260 for (i = 0; i < dev->nvqs; ++i) { 261 kfree(dev->vqs[i].indirect); 262 dev->vqs[i].indirect = NULL; 263 kfree(dev->vqs[i].log); 264 dev->vqs[i].log = NULL; 265 kfree(dev->vqs[i].heads); 266 dev->vqs[i].heads = NULL; 267 } 268 } 269 270 long vhost_dev_init(struct vhost_dev *dev, 271 struct vhost_virtqueue *vqs, int nvqs) 272 { 273 int i; 274 275 dev->vqs = vqs; 276 dev->nvqs = nvqs; 277 mutex_init(&dev->mutex); 278 dev->log_ctx = NULL; 279 dev->log_file = NULL; 280 dev->memory = NULL; 281 dev->mm = NULL; 282 spin_lock_init(&dev->work_lock); 283 INIT_LIST_HEAD(&dev->work_list); 284 dev->worker = NULL; 285 286 for (i = 0; i < dev->nvqs; ++i) { 287 dev->vqs[i].log = NULL; 288 dev->vqs[i].indirect = NULL; 289 dev->vqs[i].heads = NULL; 290 dev->vqs[i].dev = dev; 291 mutex_init(&dev->vqs[i].mutex); 292 vhost_vq_reset(dev, dev->vqs + i); 293 if (dev->vqs[i].handle_kick) 294 vhost_poll_init(&dev->vqs[i].poll, 295 dev->vqs[i].handle_kick, POLLIN, dev); 296 } 297 298 return 0; 299 } 300 301 /* Caller should have device mutex */ 302 long vhost_dev_check_owner(struct vhost_dev *dev) 303 { 304 /* Are you the owner? If not, I don't think you mean to do that */ 305 return dev->mm == current->mm ? 0 : -EPERM; 306 } 307 308 struct vhost_attach_cgroups_struct { 309 struct vhost_work work; 310 struct task_struct *owner; 311 int ret; 312 }; 313 314 static void vhost_attach_cgroups_work(struct vhost_work *work) 315 { 316 struct vhost_attach_cgroups_struct *s; 317 318 s = container_of(work, struct vhost_attach_cgroups_struct, work); 319 s->ret = cgroup_attach_task_all(s->owner, current); 320 } 321 322 static int vhost_attach_cgroups(struct vhost_dev *dev) 323 { 324 struct vhost_attach_cgroups_struct attach; 325 326 attach.owner = current; 327 vhost_work_init(&attach.work, vhost_attach_cgroups_work); 328 vhost_work_queue(dev, &attach.work); 329 vhost_work_flush(dev, &attach.work); 330 return attach.ret; 331 } 332 333 /* Caller should have device mutex */ 334 static long vhost_dev_set_owner(struct vhost_dev *dev) 335 { 336 struct task_struct *worker; 337 int err; 338 339 /* Is there an owner already? */ 340 if (dev->mm) { 341 err = -EBUSY; 342 goto err_mm; 343 } 344 345 /* No owner, become one */ 346 dev->mm = get_task_mm(current); 347 worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid); 348 if (IS_ERR(worker)) { 349 err = PTR_ERR(worker); 350 goto err_worker; 351 } 352 353 dev->worker = worker; 354 wake_up_process(worker); /* avoid contributing to loadavg */ 355 356 err = vhost_attach_cgroups(dev); 357 if (err) 358 goto err_cgroup; 359 360 err = vhost_dev_alloc_iovecs(dev); 361 if (err) 362 goto err_cgroup; 363 364 return 0; 365 err_cgroup: 366 kthread_stop(worker); 367 dev->worker = NULL; 368 err_worker: 369 if (dev->mm) 370 mmput(dev->mm); 371 dev->mm = NULL; 372 err_mm: 373 return err; 374 } 375 376 /* Caller should have device mutex */ 377 long vhost_dev_reset_owner(struct vhost_dev *dev) 378 { 379 struct vhost_memory *memory; 380 381 /* Restore memory to default empty mapping. */ 382 memory = kmalloc(offsetof(struct vhost_memory, regions), GFP_KERNEL); 383 if (!memory) 384 return -ENOMEM; 385 386 vhost_dev_cleanup(dev); 387 388 memory->nregions = 0; 389 RCU_INIT_POINTER(dev->memory, memory); 390 return 0; 391 } 392 393 /* Caller should have device mutex */ 394 void vhost_dev_cleanup(struct vhost_dev *dev) 395 { 396 int i; 397 398 for (i = 0; i < dev->nvqs; ++i) { 399 if (dev->vqs[i].kick && dev->vqs[i].handle_kick) { 400 vhost_poll_stop(&dev->vqs[i].poll); 401 vhost_poll_flush(&dev->vqs[i].poll); 402 } 403 if (dev->vqs[i].error_ctx) 404 eventfd_ctx_put(dev->vqs[i].error_ctx); 405 if (dev->vqs[i].error) 406 fput(dev->vqs[i].error); 407 if (dev->vqs[i].kick) 408 fput(dev->vqs[i].kick); 409 if (dev->vqs[i].call_ctx) 410 eventfd_ctx_put(dev->vqs[i].call_ctx); 411 if (dev->vqs[i].call) 412 fput(dev->vqs[i].call); 413 vhost_vq_reset(dev, dev->vqs + i); 414 } 415 vhost_dev_free_iovecs(dev); 416 if (dev->log_ctx) 417 eventfd_ctx_put(dev->log_ctx); 418 dev->log_ctx = NULL; 419 if (dev->log_file) 420 fput(dev->log_file); 421 dev->log_file = NULL; 422 /* No one will access memory at this point */ 423 kfree(rcu_dereference_protected(dev->memory, 424 lockdep_is_held(&dev->mutex))); 425 RCU_INIT_POINTER(dev->memory, NULL); 426 WARN_ON(!list_empty(&dev->work_list)); 427 if (dev->worker) { 428 kthread_stop(dev->worker); 429 dev->worker = NULL; 430 } 431 if (dev->mm) 432 mmput(dev->mm); 433 dev->mm = NULL; 434 } 435 436 static int log_access_ok(void __user *log_base, u64 addr, unsigned long sz) 437 { 438 u64 a = addr / VHOST_PAGE_SIZE / 8; 439 440 /* Make sure 64 bit math will not overflow. */ 441 if (a > ULONG_MAX - (unsigned long)log_base || 442 a + (unsigned long)log_base > ULONG_MAX) 443 return 0; 444 445 return access_ok(VERIFY_WRITE, log_base + a, 446 (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8); 447 } 448 449 /* Caller should have vq mutex and device mutex. */ 450 static int vq_memory_access_ok(void __user *log_base, struct vhost_memory *mem, 451 int log_all) 452 { 453 int i; 454 455 if (!mem) 456 return 0; 457 458 for (i = 0; i < mem->nregions; ++i) { 459 struct vhost_memory_region *m = mem->regions + i; 460 unsigned long a = m->userspace_addr; 461 if (m->memory_size > ULONG_MAX) 462 return 0; 463 else if (!access_ok(VERIFY_WRITE, (void __user *)a, 464 m->memory_size)) 465 return 0; 466 else if (log_all && !log_access_ok(log_base, 467 m->guest_phys_addr, 468 m->memory_size)) 469 return 0; 470 } 471 return 1; 472 } 473 474 /* Can we switch to this memory table? */ 475 /* Caller should have device mutex but not vq mutex */ 476 static int memory_access_ok(struct vhost_dev *d, struct vhost_memory *mem, 477 int log_all) 478 { 479 int i; 480 481 for (i = 0; i < d->nvqs; ++i) { 482 int ok; 483 mutex_lock(&d->vqs[i].mutex); 484 /* If ring is inactive, will check when it's enabled. */ 485 if (d->vqs[i].private_data) 486 ok = vq_memory_access_ok(d->vqs[i].log_base, mem, 487 log_all); 488 else 489 ok = 1; 490 mutex_unlock(&d->vqs[i].mutex); 491 if (!ok) 492 return 0; 493 } 494 return 1; 495 } 496 497 static int vq_access_ok(struct vhost_dev *d, unsigned int num, 498 struct vring_desc __user *desc, 499 struct vring_avail __user *avail, 500 struct vring_used __user *used) 501 { 502 size_t s = vhost_has_feature(d, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0; 503 return access_ok(VERIFY_READ, desc, num * sizeof *desc) && 504 access_ok(VERIFY_READ, avail, 505 sizeof *avail + num * sizeof *avail->ring + s) && 506 access_ok(VERIFY_WRITE, used, 507 sizeof *used + num * sizeof *used->ring + s); 508 } 509 510 /* Can we log writes? */ 511 /* Caller should have device mutex but not vq mutex */ 512 int vhost_log_access_ok(struct vhost_dev *dev) 513 { 514 struct vhost_memory *mp; 515 516 mp = rcu_dereference_protected(dev->memory, 517 lockdep_is_held(&dev->mutex)); 518 return memory_access_ok(dev, mp, 1); 519 } 520 521 /* Verify access for write logging. */ 522 /* Caller should have vq mutex and device mutex */ 523 static int vq_log_access_ok(struct vhost_dev *d, struct vhost_virtqueue *vq, 524 void __user *log_base) 525 { 526 struct vhost_memory *mp; 527 size_t s = vhost_has_feature(d, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0; 528 529 mp = rcu_dereference_protected(vq->dev->memory, 530 lockdep_is_held(&vq->mutex)); 531 return vq_memory_access_ok(log_base, mp, 532 vhost_has_feature(vq->dev, VHOST_F_LOG_ALL)) && 533 (!vq->log_used || log_access_ok(log_base, vq->log_addr, 534 sizeof *vq->used + 535 vq->num * sizeof *vq->used->ring + s)); 536 } 537 538 /* Can we start vq? */ 539 /* Caller should have vq mutex and device mutex */ 540 int vhost_vq_access_ok(struct vhost_virtqueue *vq) 541 { 542 return vq_access_ok(vq->dev, vq->num, vq->desc, vq->avail, vq->used) && 543 vq_log_access_ok(vq->dev, vq, vq->log_base); 544 } 545 546 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m) 547 { 548 struct vhost_memory mem, *newmem, *oldmem; 549 unsigned long size = offsetof(struct vhost_memory, regions); 550 551 if (copy_from_user(&mem, m, size)) 552 return -EFAULT; 553 if (mem.padding) 554 return -EOPNOTSUPP; 555 if (mem.nregions > VHOST_MEMORY_MAX_NREGIONS) 556 return -E2BIG; 557 newmem = kmalloc(size + mem.nregions * sizeof *m->regions, GFP_KERNEL); 558 if (!newmem) 559 return -ENOMEM; 560 561 memcpy(newmem, &mem, size); 562 if (copy_from_user(newmem->regions, m->regions, 563 mem.nregions * sizeof *m->regions)) { 564 kfree(newmem); 565 return -EFAULT; 566 } 567 568 if (!memory_access_ok(d, newmem, 569 vhost_has_feature(d, VHOST_F_LOG_ALL))) { 570 kfree(newmem); 571 return -EFAULT; 572 } 573 oldmem = rcu_dereference_protected(d->memory, 574 lockdep_is_held(&d->mutex)); 575 rcu_assign_pointer(d->memory, newmem); 576 synchronize_rcu(); 577 kfree(oldmem); 578 return 0; 579 } 580 581 static int init_used(struct vhost_virtqueue *vq, 582 struct vring_used __user *used) 583 { 584 int r = put_user(vq->used_flags, &used->flags); 585 586 if (r) 587 return r; 588 vq->signalled_used_valid = false; 589 return get_user(vq->last_used_idx, &used->idx); 590 } 591 592 static long vhost_set_vring(struct vhost_dev *d, int ioctl, void __user *argp) 593 { 594 struct file *eventfp, *filep = NULL, 595 *pollstart = NULL, *pollstop = NULL; 596 struct eventfd_ctx *ctx = NULL; 597 u32 __user *idxp = argp; 598 struct vhost_virtqueue *vq; 599 struct vhost_vring_state s; 600 struct vhost_vring_file f; 601 struct vhost_vring_addr a; 602 u32 idx; 603 long r; 604 605 r = get_user(idx, idxp); 606 if (r < 0) 607 return r; 608 if (idx >= d->nvqs) 609 return -ENOBUFS; 610 611 vq = d->vqs + idx; 612 613 mutex_lock(&vq->mutex); 614 615 switch (ioctl) { 616 case VHOST_SET_VRING_NUM: 617 /* Resizing ring with an active backend? 618 * You don't want to do that. */ 619 if (vq->private_data) { 620 r = -EBUSY; 621 break; 622 } 623 if (copy_from_user(&s, argp, sizeof s)) { 624 r = -EFAULT; 625 break; 626 } 627 if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) { 628 r = -EINVAL; 629 break; 630 } 631 vq->num = s.num; 632 break; 633 case VHOST_SET_VRING_BASE: 634 /* Moving base with an active backend? 635 * You don't want to do that. */ 636 if (vq->private_data) { 637 r = -EBUSY; 638 break; 639 } 640 if (copy_from_user(&s, argp, sizeof s)) { 641 r = -EFAULT; 642 break; 643 } 644 if (s.num > 0xffff) { 645 r = -EINVAL; 646 break; 647 } 648 vq->last_avail_idx = s.num; 649 /* Forget the cached index value. */ 650 vq->avail_idx = vq->last_avail_idx; 651 break; 652 case VHOST_GET_VRING_BASE: 653 s.index = idx; 654 s.num = vq->last_avail_idx; 655 if (copy_to_user(argp, &s, sizeof s)) 656 r = -EFAULT; 657 break; 658 case VHOST_SET_VRING_ADDR: 659 if (copy_from_user(&a, argp, sizeof a)) { 660 r = -EFAULT; 661 break; 662 } 663 if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) { 664 r = -EOPNOTSUPP; 665 break; 666 } 667 /* For 32bit, verify that the top 32bits of the user 668 data are set to zero. */ 669 if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr || 670 (u64)(unsigned long)a.used_user_addr != a.used_user_addr || 671 (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) { 672 r = -EFAULT; 673 break; 674 } 675 if ((a.avail_user_addr & (sizeof *vq->avail->ring - 1)) || 676 (a.used_user_addr & (sizeof *vq->used->ring - 1)) || 677 (a.log_guest_addr & (sizeof *vq->used->ring - 1))) { 678 r = -EINVAL; 679 break; 680 } 681 682 /* We only verify access here if backend is configured. 683 * If it is not, we don't as size might not have been setup. 684 * We will verify when backend is configured. */ 685 if (vq->private_data) { 686 if (!vq_access_ok(d, vq->num, 687 (void __user *)(unsigned long)a.desc_user_addr, 688 (void __user *)(unsigned long)a.avail_user_addr, 689 (void __user *)(unsigned long)a.used_user_addr)) { 690 r = -EINVAL; 691 break; 692 } 693 694 /* Also validate log access for used ring if enabled. */ 695 if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) && 696 !log_access_ok(vq->log_base, a.log_guest_addr, 697 sizeof *vq->used + 698 vq->num * sizeof *vq->used->ring)) { 699 r = -EINVAL; 700 break; 701 } 702 } 703 704 r = init_used(vq, (struct vring_used __user *)(unsigned long) 705 a.used_user_addr); 706 if (r) 707 break; 708 vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG)); 709 vq->desc = (void __user *)(unsigned long)a.desc_user_addr; 710 vq->avail = (void __user *)(unsigned long)a.avail_user_addr; 711 vq->log_addr = a.log_guest_addr; 712 vq->used = (void __user *)(unsigned long)a.used_user_addr; 713 break; 714 case VHOST_SET_VRING_KICK: 715 if (copy_from_user(&f, argp, sizeof f)) { 716 r = -EFAULT; 717 break; 718 } 719 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); 720 if (IS_ERR(eventfp)) { 721 r = PTR_ERR(eventfp); 722 break; 723 } 724 if (eventfp != vq->kick) { 725 pollstop = filep = vq->kick; 726 pollstart = vq->kick = eventfp; 727 } else 728 filep = eventfp; 729 break; 730 case VHOST_SET_VRING_CALL: 731 if (copy_from_user(&f, argp, sizeof f)) { 732 r = -EFAULT; 733 break; 734 } 735 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); 736 if (IS_ERR(eventfp)) { 737 r = PTR_ERR(eventfp); 738 break; 739 } 740 if (eventfp != vq->call) { 741 filep = vq->call; 742 ctx = vq->call_ctx; 743 vq->call = eventfp; 744 vq->call_ctx = eventfp ? 745 eventfd_ctx_fileget(eventfp) : NULL; 746 } else 747 filep = eventfp; 748 break; 749 case VHOST_SET_VRING_ERR: 750 if (copy_from_user(&f, argp, sizeof f)) { 751 r = -EFAULT; 752 break; 753 } 754 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); 755 if (IS_ERR(eventfp)) { 756 r = PTR_ERR(eventfp); 757 break; 758 } 759 if (eventfp != vq->error) { 760 filep = vq->error; 761 vq->error = eventfp; 762 ctx = vq->error_ctx; 763 vq->error_ctx = eventfp ? 764 eventfd_ctx_fileget(eventfp) : NULL; 765 } else 766 filep = eventfp; 767 break; 768 default: 769 r = -ENOIOCTLCMD; 770 } 771 772 if (pollstop && vq->handle_kick) 773 vhost_poll_stop(&vq->poll); 774 775 if (ctx) 776 eventfd_ctx_put(ctx); 777 if (filep) 778 fput(filep); 779 780 if (pollstart && vq->handle_kick) 781 vhost_poll_start(&vq->poll, vq->kick); 782 783 mutex_unlock(&vq->mutex); 784 785 if (pollstop && vq->handle_kick) 786 vhost_poll_flush(&vq->poll); 787 return r; 788 } 789 790 /* Caller must have device mutex */ 791 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, unsigned long arg) 792 { 793 void __user *argp = (void __user *)arg; 794 struct file *eventfp, *filep = NULL; 795 struct eventfd_ctx *ctx = NULL; 796 u64 p; 797 long r; 798 int i, fd; 799 800 /* If you are not the owner, you can become one */ 801 if (ioctl == VHOST_SET_OWNER) { 802 r = vhost_dev_set_owner(d); 803 goto done; 804 } 805 806 /* You must be the owner to do anything else */ 807 r = vhost_dev_check_owner(d); 808 if (r) 809 goto done; 810 811 switch (ioctl) { 812 case VHOST_SET_MEM_TABLE: 813 r = vhost_set_memory(d, argp); 814 break; 815 case VHOST_SET_LOG_BASE: 816 if (copy_from_user(&p, argp, sizeof p)) { 817 r = -EFAULT; 818 break; 819 } 820 if ((u64)(unsigned long)p != p) { 821 r = -EFAULT; 822 break; 823 } 824 for (i = 0; i < d->nvqs; ++i) { 825 struct vhost_virtqueue *vq; 826 void __user *base = (void __user *)(unsigned long)p; 827 vq = d->vqs + i; 828 mutex_lock(&vq->mutex); 829 /* If ring is inactive, will check when it's enabled. */ 830 if (vq->private_data && !vq_log_access_ok(d, vq, base)) 831 r = -EFAULT; 832 else 833 vq->log_base = base; 834 mutex_unlock(&vq->mutex); 835 } 836 break; 837 case VHOST_SET_LOG_FD: 838 r = get_user(fd, (int __user *)argp); 839 if (r < 0) 840 break; 841 eventfp = fd == -1 ? NULL : eventfd_fget(fd); 842 if (IS_ERR(eventfp)) { 843 r = PTR_ERR(eventfp); 844 break; 845 } 846 if (eventfp != d->log_file) { 847 filep = d->log_file; 848 ctx = d->log_ctx; 849 d->log_ctx = eventfp ? 850 eventfd_ctx_fileget(eventfp) : NULL; 851 } else 852 filep = eventfp; 853 for (i = 0; i < d->nvqs; ++i) { 854 mutex_lock(&d->vqs[i].mutex); 855 d->vqs[i].log_ctx = d->log_ctx; 856 mutex_unlock(&d->vqs[i].mutex); 857 } 858 if (ctx) 859 eventfd_ctx_put(ctx); 860 if (filep) 861 fput(filep); 862 break; 863 default: 864 r = vhost_set_vring(d, ioctl, argp); 865 break; 866 } 867 done: 868 return r; 869 } 870 871 static const struct vhost_memory_region *find_region(struct vhost_memory *mem, 872 __u64 addr, __u32 len) 873 { 874 struct vhost_memory_region *reg; 875 int i; 876 877 /* linear search is not brilliant, but we really have on the order of 6 878 * regions in practice */ 879 for (i = 0; i < mem->nregions; ++i) { 880 reg = mem->regions + i; 881 if (reg->guest_phys_addr <= addr && 882 reg->guest_phys_addr + reg->memory_size - 1 >= addr) 883 return reg; 884 } 885 return NULL; 886 } 887 888 /* TODO: This is really inefficient. We need something like get_user() 889 * (instruction directly accesses the data, with an exception table entry 890 * returning -EFAULT). See Documentation/x86/exception-tables.txt. 891 */ 892 static int set_bit_to_user(int nr, void __user *addr) 893 { 894 unsigned long log = (unsigned long)addr; 895 struct page *page; 896 void *base; 897 int bit = nr + (log % PAGE_SIZE) * 8; 898 int r; 899 900 r = get_user_pages_fast(log, 1, 1, &page); 901 if (r < 0) 902 return r; 903 BUG_ON(r != 1); 904 base = kmap_atomic(page, KM_USER0); 905 set_bit(bit, base); 906 kunmap_atomic(base, KM_USER0); 907 set_page_dirty_lock(page); 908 put_page(page); 909 return 0; 910 } 911 912 static int log_write(void __user *log_base, 913 u64 write_address, u64 write_length) 914 { 915 u64 write_page = write_address / VHOST_PAGE_SIZE; 916 int r; 917 918 if (!write_length) 919 return 0; 920 write_length += write_address % VHOST_PAGE_SIZE; 921 for (;;) { 922 u64 base = (u64)(unsigned long)log_base; 923 u64 log = base + write_page / 8; 924 int bit = write_page % 8; 925 if ((u64)(unsigned long)log != log) 926 return -EFAULT; 927 r = set_bit_to_user(bit, (void __user *)(unsigned long)log); 928 if (r < 0) 929 return r; 930 if (write_length <= VHOST_PAGE_SIZE) 931 break; 932 write_length -= VHOST_PAGE_SIZE; 933 write_page += 1; 934 } 935 return r; 936 } 937 938 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log, 939 unsigned int log_num, u64 len) 940 { 941 int i, r; 942 943 /* Make sure data written is seen before log. */ 944 smp_wmb(); 945 for (i = 0; i < log_num; ++i) { 946 u64 l = min(log[i].len, len); 947 r = log_write(vq->log_base, log[i].addr, l); 948 if (r < 0) 949 return r; 950 len -= l; 951 if (!len) { 952 if (vq->log_ctx) 953 eventfd_signal(vq->log_ctx, 1); 954 return 0; 955 } 956 } 957 /* Length written exceeds what we have stored. This is a bug. */ 958 BUG(); 959 return 0; 960 } 961 962 static int translate_desc(struct vhost_dev *dev, u64 addr, u32 len, 963 struct iovec iov[], int iov_size) 964 { 965 const struct vhost_memory_region *reg; 966 struct vhost_memory *mem; 967 struct iovec *_iov; 968 u64 s = 0; 969 int ret = 0; 970 971 rcu_read_lock(); 972 973 mem = rcu_dereference(dev->memory); 974 while ((u64)len > s) { 975 u64 size; 976 if (unlikely(ret >= iov_size)) { 977 ret = -ENOBUFS; 978 break; 979 } 980 reg = find_region(mem, addr, len); 981 if (unlikely(!reg)) { 982 ret = -EFAULT; 983 break; 984 } 985 _iov = iov + ret; 986 size = reg->memory_size - addr + reg->guest_phys_addr; 987 _iov->iov_len = min((u64)len, size); 988 _iov->iov_base = (void __user *)(unsigned long) 989 (reg->userspace_addr + addr - reg->guest_phys_addr); 990 s += size; 991 addr += size; 992 ++ret; 993 } 994 995 rcu_read_unlock(); 996 return ret; 997 } 998 999 /* Each buffer in the virtqueues is actually a chain of descriptors. This 1000 * function returns the next descriptor in the chain, 1001 * or -1U if we're at the end. */ 1002 static unsigned next_desc(struct vring_desc *desc) 1003 { 1004 unsigned int next; 1005 1006 /* If this descriptor says it doesn't chain, we're done. */ 1007 if (!(desc->flags & VRING_DESC_F_NEXT)) 1008 return -1U; 1009 1010 /* Check they're not leading us off end of descriptors. */ 1011 next = desc->next; 1012 /* Make sure compiler knows to grab that: we don't want it changing! */ 1013 /* We will use the result as an index in an array, so most 1014 * architectures only need a compiler barrier here. */ 1015 read_barrier_depends(); 1016 1017 return next; 1018 } 1019 1020 static int get_indirect(struct vhost_dev *dev, struct vhost_virtqueue *vq, 1021 struct iovec iov[], unsigned int iov_size, 1022 unsigned int *out_num, unsigned int *in_num, 1023 struct vhost_log *log, unsigned int *log_num, 1024 struct vring_desc *indirect) 1025 { 1026 struct vring_desc desc; 1027 unsigned int i = 0, count, found = 0; 1028 int ret; 1029 1030 /* Sanity check */ 1031 if (unlikely(indirect->len % sizeof desc)) { 1032 vq_err(vq, "Invalid length in indirect descriptor: " 1033 "len 0x%llx not multiple of 0x%zx\n", 1034 (unsigned long long)indirect->len, 1035 sizeof desc); 1036 return -EINVAL; 1037 } 1038 1039 ret = translate_desc(dev, indirect->addr, indirect->len, vq->indirect, 1040 UIO_MAXIOV); 1041 if (unlikely(ret < 0)) { 1042 vq_err(vq, "Translation failure %d in indirect.\n", ret); 1043 return ret; 1044 } 1045 1046 /* We will use the result as an address to read from, so most 1047 * architectures only need a compiler barrier here. */ 1048 read_barrier_depends(); 1049 1050 count = indirect->len / sizeof desc; 1051 /* Buffers are chained via a 16 bit next field, so 1052 * we can have at most 2^16 of these. */ 1053 if (unlikely(count > USHRT_MAX + 1)) { 1054 vq_err(vq, "Indirect buffer length too big: %d\n", 1055 indirect->len); 1056 return -E2BIG; 1057 } 1058 1059 do { 1060 unsigned iov_count = *in_num + *out_num; 1061 if (unlikely(++found > count)) { 1062 vq_err(vq, "Loop detected: last one at %u " 1063 "indirect size %u\n", 1064 i, count); 1065 return -EINVAL; 1066 } 1067 if (unlikely(memcpy_fromiovec((unsigned char *)&desc, 1068 vq->indirect, sizeof desc))) { 1069 vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n", 1070 i, (size_t)indirect->addr + i * sizeof desc); 1071 return -EINVAL; 1072 } 1073 if (unlikely(desc.flags & VRING_DESC_F_INDIRECT)) { 1074 vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n", 1075 i, (size_t)indirect->addr + i * sizeof desc); 1076 return -EINVAL; 1077 } 1078 1079 ret = translate_desc(dev, desc.addr, desc.len, iov + iov_count, 1080 iov_size - iov_count); 1081 if (unlikely(ret < 0)) { 1082 vq_err(vq, "Translation failure %d indirect idx %d\n", 1083 ret, i); 1084 return ret; 1085 } 1086 /* If this is an input descriptor, increment that count. */ 1087 if (desc.flags & VRING_DESC_F_WRITE) { 1088 *in_num += ret; 1089 if (unlikely(log)) { 1090 log[*log_num].addr = desc.addr; 1091 log[*log_num].len = desc.len; 1092 ++*log_num; 1093 } 1094 } else { 1095 /* If it's an output descriptor, they're all supposed 1096 * to come before any input descriptors. */ 1097 if (unlikely(*in_num)) { 1098 vq_err(vq, "Indirect descriptor " 1099 "has out after in: idx %d\n", i); 1100 return -EINVAL; 1101 } 1102 *out_num += ret; 1103 } 1104 } while ((i = next_desc(&desc)) != -1); 1105 return 0; 1106 } 1107 1108 /* This looks in the virtqueue and for the first available buffer, and converts 1109 * it to an iovec for convenient access. Since descriptors consist of some 1110 * number of output then some number of input descriptors, it's actually two 1111 * iovecs, but we pack them into one and note how many of each there were. 1112 * 1113 * This function returns the descriptor number found, or vq->num (which is 1114 * never a valid descriptor number) if none was found. A negative code is 1115 * returned on error. */ 1116 int vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq, 1117 struct iovec iov[], unsigned int iov_size, 1118 unsigned int *out_num, unsigned int *in_num, 1119 struct vhost_log *log, unsigned int *log_num) 1120 { 1121 struct vring_desc desc; 1122 unsigned int i, head, found = 0; 1123 u16 last_avail_idx; 1124 int ret; 1125 1126 /* Check it isn't doing very strange things with descriptor numbers. */ 1127 last_avail_idx = vq->last_avail_idx; 1128 if (unlikely(__get_user(vq->avail_idx, &vq->avail->idx))) { 1129 vq_err(vq, "Failed to access avail idx at %p\n", 1130 &vq->avail->idx); 1131 return -EFAULT; 1132 } 1133 1134 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) { 1135 vq_err(vq, "Guest moved used index from %u to %u", 1136 last_avail_idx, vq->avail_idx); 1137 return -EFAULT; 1138 } 1139 1140 /* If there's nothing new since last we looked, return invalid. */ 1141 if (vq->avail_idx == last_avail_idx) 1142 return vq->num; 1143 1144 /* Only get avail ring entries after they have been exposed by guest. */ 1145 smp_rmb(); 1146 1147 /* Grab the next descriptor number they're advertising, and increment 1148 * the index we've seen. */ 1149 if (unlikely(__get_user(head, 1150 &vq->avail->ring[last_avail_idx % vq->num]))) { 1151 vq_err(vq, "Failed to read head: idx %d address %p\n", 1152 last_avail_idx, 1153 &vq->avail->ring[last_avail_idx % vq->num]); 1154 return -EFAULT; 1155 } 1156 1157 /* If their number is silly, that's an error. */ 1158 if (unlikely(head >= vq->num)) { 1159 vq_err(vq, "Guest says index %u > %u is available", 1160 head, vq->num); 1161 return -EINVAL; 1162 } 1163 1164 /* When we start there are none of either input nor output. */ 1165 *out_num = *in_num = 0; 1166 if (unlikely(log)) 1167 *log_num = 0; 1168 1169 i = head; 1170 do { 1171 unsigned iov_count = *in_num + *out_num; 1172 if (unlikely(i >= vq->num)) { 1173 vq_err(vq, "Desc index is %u > %u, head = %u", 1174 i, vq->num, head); 1175 return -EINVAL; 1176 } 1177 if (unlikely(++found > vq->num)) { 1178 vq_err(vq, "Loop detected: last one at %u " 1179 "vq size %u head %u\n", 1180 i, vq->num, head); 1181 return -EINVAL; 1182 } 1183 ret = __copy_from_user(&desc, vq->desc + i, sizeof desc); 1184 if (unlikely(ret)) { 1185 vq_err(vq, "Failed to get descriptor: idx %d addr %p\n", 1186 i, vq->desc + i); 1187 return -EFAULT; 1188 } 1189 if (desc.flags & VRING_DESC_F_INDIRECT) { 1190 ret = get_indirect(dev, vq, iov, iov_size, 1191 out_num, in_num, 1192 log, log_num, &desc); 1193 if (unlikely(ret < 0)) { 1194 vq_err(vq, "Failure detected " 1195 "in indirect descriptor at idx %d\n", i); 1196 return ret; 1197 } 1198 continue; 1199 } 1200 1201 ret = translate_desc(dev, desc.addr, desc.len, iov + iov_count, 1202 iov_size - iov_count); 1203 if (unlikely(ret < 0)) { 1204 vq_err(vq, "Translation failure %d descriptor idx %d\n", 1205 ret, i); 1206 return ret; 1207 } 1208 if (desc.flags & VRING_DESC_F_WRITE) { 1209 /* If this is an input descriptor, 1210 * increment that count. */ 1211 *in_num += ret; 1212 if (unlikely(log)) { 1213 log[*log_num].addr = desc.addr; 1214 log[*log_num].len = desc.len; 1215 ++*log_num; 1216 } 1217 } else { 1218 /* If it's an output descriptor, they're all supposed 1219 * to come before any input descriptors. */ 1220 if (unlikely(*in_num)) { 1221 vq_err(vq, "Descriptor has out after in: " 1222 "idx %d\n", i); 1223 return -EINVAL; 1224 } 1225 *out_num += ret; 1226 } 1227 } while ((i = next_desc(&desc)) != -1); 1228 1229 /* On success, increment avail index. */ 1230 vq->last_avail_idx++; 1231 1232 /* Assume notifications from guest are disabled at this point, 1233 * if they aren't we would need to update avail_event index. */ 1234 BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY)); 1235 return head; 1236 } 1237 1238 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */ 1239 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n) 1240 { 1241 vq->last_avail_idx -= n; 1242 } 1243 1244 /* After we've used one of their buffers, we tell them about it. We'll then 1245 * want to notify the guest, using eventfd. */ 1246 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len) 1247 { 1248 struct vring_used_elem __user *used; 1249 1250 /* The virtqueue contains a ring of used buffers. Get a pointer to the 1251 * next entry in that used ring. */ 1252 used = &vq->used->ring[vq->last_used_idx % vq->num]; 1253 if (__put_user(head, &used->id)) { 1254 vq_err(vq, "Failed to write used id"); 1255 return -EFAULT; 1256 } 1257 if (__put_user(len, &used->len)) { 1258 vq_err(vq, "Failed to write used len"); 1259 return -EFAULT; 1260 } 1261 /* Make sure buffer is written before we update index. */ 1262 smp_wmb(); 1263 if (__put_user(vq->last_used_idx + 1, &vq->used->idx)) { 1264 vq_err(vq, "Failed to increment used idx"); 1265 return -EFAULT; 1266 } 1267 if (unlikely(vq->log_used)) { 1268 /* Make sure data is seen before log. */ 1269 smp_wmb(); 1270 /* Log used ring entry write. */ 1271 log_write(vq->log_base, 1272 vq->log_addr + 1273 ((void __user *)used - (void __user *)vq->used), 1274 sizeof *used); 1275 /* Log used index update. */ 1276 log_write(vq->log_base, 1277 vq->log_addr + offsetof(struct vring_used, idx), 1278 sizeof vq->used->idx); 1279 if (vq->log_ctx) 1280 eventfd_signal(vq->log_ctx, 1); 1281 } 1282 vq->last_used_idx++; 1283 /* If the driver never bothers to signal in a very long while, 1284 * used index might wrap around. If that happens, invalidate 1285 * signalled_used index we stored. TODO: make sure driver 1286 * signals at least once in 2^16 and remove this. */ 1287 if (unlikely(vq->last_used_idx == vq->signalled_used)) 1288 vq->signalled_used_valid = false; 1289 return 0; 1290 } 1291 1292 static int __vhost_add_used_n(struct vhost_virtqueue *vq, 1293 struct vring_used_elem *heads, 1294 unsigned count) 1295 { 1296 struct vring_used_elem __user *used; 1297 u16 old, new; 1298 int start; 1299 1300 start = vq->last_used_idx % vq->num; 1301 used = vq->used->ring + start; 1302 if (__copy_to_user(used, heads, count * sizeof *used)) { 1303 vq_err(vq, "Failed to write used"); 1304 return -EFAULT; 1305 } 1306 if (unlikely(vq->log_used)) { 1307 /* Make sure data is seen before log. */ 1308 smp_wmb(); 1309 /* Log used ring entry write. */ 1310 log_write(vq->log_base, 1311 vq->log_addr + 1312 ((void __user *)used - (void __user *)vq->used), 1313 count * sizeof *used); 1314 } 1315 old = vq->last_used_idx; 1316 new = (vq->last_used_idx += count); 1317 /* If the driver never bothers to signal in a very long while, 1318 * used index might wrap around. If that happens, invalidate 1319 * signalled_used index we stored. TODO: make sure driver 1320 * signals at least once in 2^16 and remove this. */ 1321 if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old))) 1322 vq->signalled_used_valid = false; 1323 return 0; 1324 } 1325 1326 /* After we've used one of their buffers, we tell them about it. We'll then 1327 * want to notify the guest, using eventfd. */ 1328 int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads, 1329 unsigned count) 1330 { 1331 int start, n, r; 1332 1333 start = vq->last_used_idx % vq->num; 1334 n = vq->num - start; 1335 if (n < count) { 1336 r = __vhost_add_used_n(vq, heads, n); 1337 if (r < 0) 1338 return r; 1339 heads += n; 1340 count -= n; 1341 } 1342 r = __vhost_add_used_n(vq, heads, count); 1343 1344 /* Make sure buffer is written before we update index. */ 1345 smp_wmb(); 1346 if (put_user(vq->last_used_idx, &vq->used->idx)) { 1347 vq_err(vq, "Failed to increment used idx"); 1348 return -EFAULT; 1349 } 1350 if (unlikely(vq->log_used)) { 1351 /* Log used index update. */ 1352 log_write(vq->log_base, 1353 vq->log_addr + offsetof(struct vring_used, idx), 1354 sizeof vq->used->idx); 1355 if (vq->log_ctx) 1356 eventfd_signal(vq->log_ctx, 1); 1357 } 1358 return r; 1359 } 1360 1361 static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) 1362 { 1363 __u16 old, new, event; 1364 bool v; 1365 /* Flush out used index updates. This is paired 1366 * with the barrier that the Guest executes when enabling 1367 * interrupts. */ 1368 smp_mb(); 1369 1370 if (vhost_has_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY) && 1371 unlikely(vq->avail_idx == vq->last_avail_idx)) 1372 return true; 1373 1374 if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) { 1375 __u16 flags; 1376 if (__get_user(flags, &vq->avail->flags)) { 1377 vq_err(vq, "Failed to get flags"); 1378 return true; 1379 } 1380 return !(flags & VRING_AVAIL_F_NO_INTERRUPT); 1381 } 1382 old = vq->signalled_used; 1383 v = vq->signalled_used_valid; 1384 new = vq->signalled_used = vq->last_used_idx; 1385 vq->signalled_used_valid = true; 1386 1387 if (unlikely(!v)) 1388 return true; 1389 1390 if (get_user(event, vhost_used_event(vq))) { 1391 vq_err(vq, "Failed to get used event idx"); 1392 return true; 1393 } 1394 return vring_need_event(event, new, old); 1395 } 1396 1397 /* This actually signals the guest, using eventfd. */ 1398 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq) 1399 { 1400 /* Signal the Guest tell them we used something up. */ 1401 if (vq->call_ctx && vhost_notify(dev, vq)) 1402 eventfd_signal(vq->call_ctx, 1); 1403 } 1404 1405 /* And here's the combo meal deal. Supersize me! */ 1406 void vhost_add_used_and_signal(struct vhost_dev *dev, 1407 struct vhost_virtqueue *vq, 1408 unsigned int head, int len) 1409 { 1410 vhost_add_used(vq, head, len); 1411 vhost_signal(dev, vq); 1412 } 1413 1414 /* multi-buffer version of vhost_add_used_and_signal */ 1415 void vhost_add_used_and_signal_n(struct vhost_dev *dev, 1416 struct vhost_virtqueue *vq, 1417 struct vring_used_elem *heads, unsigned count) 1418 { 1419 vhost_add_used_n(vq, heads, count); 1420 vhost_signal(dev, vq); 1421 } 1422 1423 /* OK, now we need to know about added descriptors. */ 1424 bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) 1425 { 1426 u16 avail_idx; 1427 int r; 1428 1429 if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY)) 1430 return false; 1431 vq->used_flags &= ~VRING_USED_F_NO_NOTIFY; 1432 if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) { 1433 r = put_user(vq->used_flags, &vq->used->flags); 1434 if (r) { 1435 vq_err(vq, "Failed to enable notification at %p: %d\n", 1436 &vq->used->flags, r); 1437 return false; 1438 } 1439 } else { 1440 r = put_user(vq->avail_idx, vhost_avail_event(vq)); 1441 if (r) { 1442 vq_err(vq, "Failed to update avail event index at %p: %d\n", 1443 vhost_avail_event(vq), r); 1444 return false; 1445 } 1446 } 1447 if (unlikely(vq->log_used)) { 1448 void __user *used; 1449 /* Make sure data is seen before log. */ 1450 smp_wmb(); 1451 used = vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX) ? 1452 &vq->used->flags : vhost_avail_event(vq); 1453 /* Log used flags or event index entry write. Both are 16 bit 1454 * fields. */ 1455 log_write(vq->log_base, vq->log_addr + 1456 (used - (void __user *)vq->used), 1457 sizeof(u16)); 1458 if (vq->log_ctx) 1459 eventfd_signal(vq->log_ctx, 1); 1460 } 1461 /* They could have slipped one in as we were doing that: make 1462 * sure it's written, then check again. */ 1463 smp_mb(); 1464 r = __get_user(avail_idx, &vq->avail->idx); 1465 if (r) { 1466 vq_err(vq, "Failed to check avail idx at %p: %d\n", 1467 &vq->avail->idx, r); 1468 return false; 1469 } 1470 1471 return avail_idx != vq->avail_idx; 1472 } 1473 1474 /* We don't need to be notified again. */ 1475 void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) 1476 { 1477 int r; 1478 1479 if (vq->used_flags & VRING_USED_F_NO_NOTIFY) 1480 return; 1481 vq->used_flags |= VRING_USED_F_NO_NOTIFY; 1482 if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) { 1483 r = put_user(vq->used_flags, &vq->used->flags); 1484 if (r) 1485 vq_err(vq, "Failed to enable notification at %p: %d\n", 1486 &vq->used->flags, r); 1487 } 1488 } 1489