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