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