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/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/miscdevice.h> 19 #include <linux/mutex.h> 20 #include <linux/rcupdate.h> 21 #include <linux/poll.h> 22 #include <linux/file.h> 23 #include <linux/highmem.h> 24 #include <linux/slab.h> 25 #include <linux/kthread.h> 26 #include <linux/cgroup.h> 27 28 #include <linux/net.h> 29 #include <linux/if_packet.h> 30 #include <linux/if_arp.h> 31 32 #include <net/sock.h> 33 34 #include "vhost.h" 35 36 enum { 37 VHOST_MEMORY_MAX_NREGIONS = 64, 38 VHOST_MEMORY_F_LOG = 0x1, 39 }; 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 poll = container_of(pt, struct vhost_poll, table); 46 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 /* Init poll structure */ 64 void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn, 65 unsigned long mask, struct vhost_dev *dev) 66 { 67 struct vhost_work *work = &poll->work; 68 69 init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup); 70 init_poll_funcptr(&poll->table, vhost_poll_func); 71 poll->mask = mask; 72 poll->dev = dev; 73 74 INIT_LIST_HEAD(&work->node); 75 work->fn = fn; 76 init_waitqueue_head(&work->done); 77 work->flushing = 0; 78 work->queue_seq = work->done_seq = 0; 79 } 80 81 /* Start polling a file. We add ourselves to file's wait queue. The caller must 82 * keep a reference to a file until after vhost_poll_stop is called. */ 83 void vhost_poll_start(struct vhost_poll *poll, struct file *file) 84 { 85 unsigned long mask; 86 mask = file->f_op->poll(file, &poll->table); 87 if (mask) 88 vhost_poll_wakeup(&poll->wait, 0, 0, (void *)mask); 89 } 90 91 /* Stop polling a file. After this function returns, it becomes safe to drop the 92 * file reference. You must also flush afterwards. */ 93 void vhost_poll_stop(struct vhost_poll *poll) 94 { 95 remove_wait_queue(poll->wqh, &poll->wait); 96 } 97 98 /* Flush any work that has been scheduled. When calling this, don't hold any 99 * locks that are also used by the callback. */ 100 void vhost_poll_flush(struct vhost_poll *poll) 101 { 102 struct vhost_work *work = &poll->work; 103 unsigned seq; 104 int left; 105 int flushing; 106 107 spin_lock_irq(&poll->dev->work_lock); 108 seq = work->queue_seq; 109 work->flushing++; 110 spin_unlock_irq(&poll->dev->work_lock); 111 wait_event(work->done, ({ 112 spin_lock_irq(&poll->dev->work_lock); 113 left = seq - work->done_seq <= 0; 114 spin_unlock_irq(&poll->dev->work_lock); 115 left; 116 })); 117 spin_lock_irq(&poll->dev->work_lock); 118 flushing = --work->flushing; 119 spin_unlock_irq(&poll->dev->work_lock); 120 BUG_ON(flushing < 0); 121 } 122 123 void vhost_poll_queue(struct vhost_poll *poll) 124 { 125 struct vhost_dev *dev = poll->dev; 126 struct vhost_work *work = &poll->work; 127 unsigned long flags; 128 129 spin_lock_irqsave(&dev->work_lock, flags); 130 if (list_empty(&work->node)) { 131 list_add_tail(&work->node, &dev->work_list); 132 work->queue_seq++; 133 wake_up_process(dev->worker); 134 } 135 spin_unlock_irqrestore(&dev->work_lock, flags); 136 } 137 138 static void vhost_vq_reset(struct vhost_dev *dev, 139 struct vhost_virtqueue *vq) 140 { 141 vq->num = 1; 142 vq->desc = NULL; 143 vq->avail = NULL; 144 vq->used = NULL; 145 vq->last_avail_idx = 0; 146 vq->avail_idx = 0; 147 vq->last_used_idx = 0; 148 vq->used_flags = 0; 149 vq->used_flags = 0; 150 vq->log_used = false; 151 vq->log_addr = -1ull; 152 vq->vhost_hlen = 0; 153 vq->sock_hlen = 0; 154 vq->private_data = NULL; 155 vq->log_base = NULL; 156 vq->error_ctx = NULL; 157 vq->error = NULL; 158 vq->kick = NULL; 159 vq->call_ctx = NULL; 160 vq->call = NULL; 161 vq->log_ctx = NULL; 162 } 163 164 static int vhost_worker(void *data) 165 { 166 struct vhost_dev *dev = data; 167 struct vhost_work *work = NULL; 168 unsigned uninitialized_var(seq); 169 170 for (;;) { 171 /* mb paired w/ kthread_stop */ 172 set_current_state(TASK_INTERRUPTIBLE); 173 174 spin_lock_irq(&dev->work_lock); 175 if (work) { 176 work->done_seq = seq; 177 if (work->flushing) 178 wake_up_all(&work->done); 179 } 180 181 if (kthread_should_stop()) { 182 spin_unlock_irq(&dev->work_lock); 183 __set_current_state(TASK_RUNNING); 184 return 0; 185 } 186 if (!list_empty(&dev->work_list)) { 187 work = list_first_entry(&dev->work_list, 188 struct vhost_work, node); 189 list_del_init(&work->node); 190 seq = work->queue_seq; 191 } else 192 work = NULL; 193 spin_unlock_irq(&dev->work_lock); 194 195 if (work) { 196 __set_current_state(TASK_RUNNING); 197 work->fn(work); 198 } else 199 schedule(); 200 201 } 202 } 203 204 long vhost_dev_init(struct vhost_dev *dev, 205 struct vhost_virtqueue *vqs, int nvqs) 206 { 207 int i; 208 209 dev->vqs = vqs; 210 dev->nvqs = nvqs; 211 mutex_init(&dev->mutex); 212 dev->log_ctx = NULL; 213 dev->log_file = NULL; 214 dev->memory = NULL; 215 dev->mm = NULL; 216 spin_lock_init(&dev->work_lock); 217 INIT_LIST_HEAD(&dev->work_list); 218 dev->worker = NULL; 219 220 for (i = 0; i < dev->nvqs; ++i) { 221 dev->vqs[i].dev = dev; 222 mutex_init(&dev->vqs[i].mutex); 223 vhost_vq_reset(dev, dev->vqs + i); 224 if (dev->vqs[i].handle_kick) 225 vhost_poll_init(&dev->vqs[i].poll, 226 dev->vqs[i].handle_kick, POLLIN, dev); 227 } 228 229 return 0; 230 } 231 232 /* Caller should have device mutex */ 233 long vhost_dev_check_owner(struct vhost_dev *dev) 234 { 235 /* Are you the owner? If not, I don't think you mean to do that */ 236 return dev->mm == current->mm ? 0 : -EPERM; 237 } 238 239 /* Caller should have device mutex */ 240 static long vhost_dev_set_owner(struct vhost_dev *dev) 241 { 242 struct task_struct *worker; 243 int err; 244 /* Is there an owner already? */ 245 if (dev->mm) { 246 err = -EBUSY; 247 goto err_mm; 248 } 249 /* No owner, become one */ 250 dev->mm = get_task_mm(current); 251 worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid); 252 if (IS_ERR(worker)) { 253 err = PTR_ERR(worker); 254 goto err_worker; 255 } 256 257 dev->worker = worker; 258 err = cgroup_attach_task_current_cg(worker); 259 if (err) 260 goto err_cgroup; 261 wake_up_process(worker); /* avoid contributing to loadavg */ 262 263 return 0; 264 err_cgroup: 265 kthread_stop(worker); 266 err_worker: 267 if (dev->mm) 268 mmput(dev->mm); 269 dev->mm = NULL; 270 err_mm: 271 return err; 272 } 273 274 /* Caller should have device mutex */ 275 long vhost_dev_reset_owner(struct vhost_dev *dev) 276 { 277 struct vhost_memory *memory; 278 279 /* Restore memory to default empty mapping. */ 280 memory = kmalloc(offsetof(struct vhost_memory, regions), GFP_KERNEL); 281 if (!memory) 282 return -ENOMEM; 283 284 vhost_dev_cleanup(dev); 285 286 memory->nregions = 0; 287 dev->memory = memory; 288 return 0; 289 } 290 291 /* Caller should have device mutex */ 292 void vhost_dev_cleanup(struct vhost_dev *dev) 293 { 294 int i; 295 for (i = 0; i < dev->nvqs; ++i) { 296 if (dev->vqs[i].kick && dev->vqs[i].handle_kick) { 297 vhost_poll_stop(&dev->vqs[i].poll); 298 vhost_poll_flush(&dev->vqs[i].poll); 299 } 300 if (dev->vqs[i].error_ctx) 301 eventfd_ctx_put(dev->vqs[i].error_ctx); 302 if (dev->vqs[i].error) 303 fput(dev->vqs[i].error); 304 if (dev->vqs[i].kick) 305 fput(dev->vqs[i].kick); 306 if (dev->vqs[i].call_ctx) 307 eventfd_ctx_put(dev->vqs[i].call_ctx); 308 if (dev->vqs[i].call) 309 fput(dev->vqs[i].call); 310 vhost_vq_reset(dev, dev->vqs + i); 311 } 312 if (dev->log_ctx) 313 eventfd_ctx_put(dev->log_ctx); 314 dev->log_ctx = NULL; 315 if (dev->log_file) 316 fput(dev->log_file); 317 dev->log_file = NULL; 318 /* No one will access memory at this point */ 319 kfree(dev->memory); 320 dev->memory = NULL; 321 if (dev->mm) 322 mmput(dev->mm); 323 dev->mm = NULL; 324 325 WARN_ON(!list_empty(&dev->work_list)); 326 kthread_stop(dev->worker); 327 } 328 329 static int log_access_ok(void __user *log_base, u64 addr, unsigned long sz) 330 { 331 u64 a = addr / VHOST_PAGE_SIZE / 8; 332 /* Make sure 64 bit math will not overflow. */ 333 if (a > ULONG_MAX - (unsigned long)log_base || 334 a + (unsigned long)log_base > ULONG_MAX) 335 return -EFAULT; 336 337 return access_ok(VERIFY_WRITE, log_base + a, 338 (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8); 339 } 340 341 /* Caller should have vq mutex and device mutex. */ 342 static int vq_memory_access_ok(void __user *log_base, struct vhost_memory *mem, 343 int log_all) 344 { 345 int i; 346 347 if (!mem) 348 return 0; 349 350 for (i = 0; i < mem->nregions; ++i) { 351 struct vhost_memory_region *m = mem->regions + i; 352 unsigned long a = m->userspace_addr; 353 if (m->memory_size > ULONG_MAX) 354 return 0; 355 else if (!access_ok(VERIFY_WRITE, (void __user *)a, 356 m->memory_size)) 357 return 0; 358 else if (log_all && !log_access_ok(log_base, 359 m->guest_phys_addr, 360 m->memory_size)) 361 return 0; 362 } 363 return 1; 364 } 365 366 /* Can we switch to this memory table? */ 367 /* Caller should have device mutex but not vq mutex */ 368 static int memory_access_ok(struct vhost_dev *d, struct vhost_memory *mem, 369 int log_all) 370 { 371 int i; 372 for (i = 0; i < d->nvqs; ++i) { 373 int ok; 374 mutex_lock(&d->vqs[i].mutex); 375 /* If ring is inactive, will check when it's enabled. */ 376 if (d->vqs[i].private_data) 377 ok = vq_memory_access_ok(d->vqs[i].log_base, mem, 378 log_all); 379 else 380 ok = 1; 381 mutex_unlock(&d->vqs[i].mutex); 382 if (!ok) 383 return 0; 384 } 385 return 1; 386 } 387 388 static int vq_access_ok(unsigned int num, 389 struct vring_desc __user *desc, 390 struct vring_avail __user *avail, 391 struct vring_used __user *used) 392 { 393 return access_ok(VERIFY_READ, desc, num * sizeof *desc) && 394 access_ok(VERIFY_READ, avail, 395 sizeof *avail + num * sizeof *avail->ring) && 396 access_ok(VERIFY_WRITE, used, 397 sizeof *used + num * sizeof *used->ring); 398 } 399 400 /* Can we log writes? */ 401 /* Caller should have device mutex but not vq mutex */ 402 int vhost_log_access_ok(struct vhost_dev *dev) 403 { 404 return memory_access_ok(dev, dev->memory, 1); 405 } 406 407 /* Verify access for write logging. */ 408 /* Caller should have vq mutex and device mutex */ 409 static int vq_log_access_ok(struct vhost_virtqueue *vq, void __user *log_base) 410 { 411 return vq_memory_access_ok(log_base, vq->dev->memory, 412 vhost_has_feature(vq->dev, VHOST_F_LOG_ALL)) && 413 (!vq->log_used || log_access_ok(log_base, vq->log_addr, 414 sizeof *vq->used + 415 vq->num * sizeof *vq->used->ring)); 416 } 417 418 /* Can we start vq? */ 419 /* Caller should have vq mutex and device mutex */ 420 int vhost_vq_access_ok(struct vhost_virtqueue *vq) 421 { 422 return vq_access_ok(vq->num, vq->desc, vq->avail, vq->used) && 423 vq_log_access_ok(vq, vq->log_base); 424 } 425 426 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m) 427 { 428 struct vhost_memory mem, *newmem, *oldmem; 429 unsigned long size = offsetof(struct vhost_memory, regions); 430 if (copy_from_user(&mem, m, size)) 431 return -EFAULT; 432 if (mem.padding) 433 return -EOPNOTSUPP; 434 if (mem.nregions > VHOST_MEMORY_MAX_NREGIONS) 435 return -E2BIG; 436 newmem = kmalloc(size + mem.nregions * sizeof *m->regions, GFP_KERNEL); 437 if (!newmem) 438 return -ENOMEM; 439 440 memcpy(newmem, &mem, size); 441 if (copy_from_user(newmem->regions, m->regions, 442 mem.nregions * sizeof *m->regions)) { 443 kfree(newmem); 444 return -EFAULT; 445 } 446 447 if (!memory_access_ok(d, newmem, vhost_has_feature(d, VHOST_F_LOG_ALL))) { 448 kfree(newmem); 449 return -EFAULT; 450 } 451 oldmem = d->memory; 452 rcu_assign_pointer(d->memory, newmem); 453 synchronize_rcu(); 454 kfree(oldmem); 455 return 0; 456 } 457 458 static int init_used(struct vhost_virtqueue *vq, 459 struct vring_used __user *used) 460 { 461 int r = put_user(vq->used_flags, &used->flags); 462 if (r) 463 return r; 464 return get_user(vq->last_used_idx, &used->idx); 465 } 466 467 static long vhost_set_vring(struct vhost_dev *d, int ioctl, void __user *argp) 468 { 469 struct file *eventfp, *filep = NULL, 470 *pollstart = NULL, *pollstop = NULL; 471 struct eventfd_ctx *ctx = NULL; 472 u32 __user *idxp = argp; 473 struct vhost_virtqueue *vq; 474 struct vhost_vring_state s; 475 struct vhost_vring_file f; 476 struct vhost_vring_addr a; 477 u32 idx; 478 long r; 479 480 r = get_user(idx, idxp); 481 if (r < 0) 482 return r; 483 if (idx >= d->nvqs) 484 return -ENOBUFS; 485 486 vq = d->vqs + idx; 487 488 mutex_lock(&vq->mutex); 489 490 switch (ioctl) { 491 case VHOST_SET_VRING_NUM: 492 /* Resizing ring with an active backend? 493 * You don't want to do that. */ 494 if (vq->private_data) { 495 r = -EBUSY; 496 break; 497 } 498 if (copy_from_user(&s, argp, sizeof s)) { 499 r = -EFAULT; 500 break; 501 } 502 if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) { 503 r = -EINVAL; 504 break; 505 } 506 vq->num = s.num; 507 break; 508 case VHOST_SET_VRING_BASE: 509 /* Moving base with an active backend? 510 * You don't want to do that. */ 511 if (vq->private_data) { 512 r = -EBUSY; 513 break; 514 } 515 if (copy_from_user(&s, argp, sizeof s)) { 516 r = -EFAULT; 517 break; 518 } 519 if (s.num > 0xffff) { 520 r = -EINVAL; 521 break; 522 } 523 vq->last_avail_idx = s.num; 524 /* Forget the cached index value. */ 525 vq->avail_idx = vq->last_avail_idx; 526 break; 527 case VHOST_GET_VRING_BASE: 528 s.index = idx; 529 s.num = vq->last_avail_idx; 530 if (copy_to_user(argp, &s, sizeof s)) 531 r = -EFAULT; 532 break; 533 case VHOST_SET_VRING_ADDR: 534 if (copy_from_user(&a, argp, sizeof a)) { 535 r = -EFAULT; 536 break; 537 } 538 if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) { 539 r = -EOPNOTSUPP; 540 break; 541 } 542 /* For 32bit, verify that the top 32bits of the user 543 data are set to zero. */ 544 if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr || 545 (u64)(unsigned long)a.used_user_addr != a.used_user_addr || 546 (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) { 547 r = -EFAULT; 548 break; 549 } 550 if ((a.avail_user_addr & (sizeof *vq->avail->ring - 1)) || 551 (a.used_user_addr & (sizeof *vq->used->ring - 1)) || 552 (a.log_guest_addr & (sizeof *vq->used->ring - 1))) { 553 r = -EINVAL; 554 break; 555 } 556 557 /* We only verify access here if backend is configured. 558 * If it is not, we don't as size might not have been setup. 559 * We will verify when backend is configured. */ 560 if (vq->private_data) { 561 if (!vq_access_ok(vq->num, 562 (void __user *)(unsigned long)a.desc_user_addr, 563 (void __user *)(unsigned long)a.avail_user_addr, 564 (void __user *)(unsigned long)a.used_user_addr)) { 565 r = -EINVAL; 566 break; 567 } 568 569 /* Also validate log access for used ring if enabled. */ 570 if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) && 571 !log_access_ok(vq->log_base, a.log_guest_addr, 572 sizeof *vq->used + 573 vq->num * sizeof *vq->used->ring)) { 574 r = -EINVAL; 575 break; 576 } 577 } 578 579 r = init_used(vq, (struct vring_used __user *)(unsigned long) 580 a.used_user_addr); 581 if (r) 582 break; 583 vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG)); 584 vq->desc = (void __user *)(unsigned long)a.desc_user_addr; 585 vq->avail = (void __user *)(unsigned long)a.avail_user_addr; 586 vq->log_addr = a.log_guest_addr; 587 vq->used = (void __user *)(unsigned long)a.used_user_addr; 588 break; 589 case VHOST_SET_VRING_KICK: 590 if (copy_from_user(&f, argp, sizeof f)) { 591 r = -EFAULT; 592 break; 593 } 594 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); 595 if (IS_ERR(eventfp)) { 596 r = PTR_ERR(eventfp); 597 break; 598 } 599 if (eventfp != vq->kick) { 600 pollstop = filep = vq->kick; 601 pollstart = vq->kick = eventfp; 602 } else 603 filep = eventfp; 604 break; 605 case VHOST_SET_VRING_CALL: 606 if (copy_from_user(&f, argp, sizeof f)) { 607 r = -EFAULT; 608 break; 609 } 610 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); 611 if (IS_ERR(eventfp)) { 612 r = PTR_ERR(eventfp); 613 break; 614 } 615 if (eventfp != vq->call) { 616 filep = vq->call; 617 ctx = vq->call_ctx; 618 vq->call = eventfp; 619 vq->call_ctx = eventfp ? 620 eventfd_ctx_fileget(eventfp) : NULL; 621 } else 622 filep = eventfp; 623 break; 624 case VHOST_SET_VRING_ERR: 625 if (copy_from_user(&f, argp, sizeof f)) { 626 r = -EFAULT; 627 break; 628 } 629 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); 630 if (IS_ERR(eventfp)) { 631 r = PTR_ERR(eventfp); 632 break; 633 } 634 if (eventfp != vq->error) { 635 filep = vq->error; 636 vq->error = eventfp; 637 ctx = vq->error_ctx; 638 vq->error_ctx = eventfp ? 639 eventfd_ctx_fileget(eventfp) : NULL; 640 } else 641 filep = eventfp; 642 break; 643 default: 644 r = -ENOIOCTLCMD; 645 } 646 647 if (pollstop && vq->handle_kick) 648 vhost_poll_stop(&vq->poll); 649 650 if (ctx) 651 eventfd_ctx_put(ctx); 652 if (filep) 653 fput(filep); 654 655 if (pollstart && vq->handle_kick) 656 vhost_poll_start(&vq->poll, vq->kick); 657 658 mutex_unlock(&vq->mutex); 659 660 if (pollstop && vq->handle_kick) 661 vhost_poll_flush(&vq->poll); 662 return r; 663 } 664 665 /* Caller must have device mutex */ 666 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, unsigned long arg) 667 { 668 void __user *argp = (void __user *)arg; 669 struct file *eventfp, *filep = NULL; 670 struct eventfd_ctx *ctx = NULL; 671 u64 p; 672 long r; 673 int i, fd; 674 675 /* If you are not the owner, you can become one */ 676 if (ioctl == VHOST_SET_OWNER) { 677 r = vhost_dev_set_owner(d); 678 goto done; 679 } 680 681 /* You must be the owner to do anything else */ 682 r = vhost_dev_check_owner(d); 683 if (r) 684 goto done; 685 686 switch (ioctl) { 687 case VHOST_SET_MEM_TABLE: 688 r = vhost_set_memory(d, argp); 689 break; 690 case VHOST_SET_LOG_BASE: 691 if (copy_from_user(&p, argp, sizeof p)) { 692 r = -EFAULT; 693 break; 694 } 695 if ((u64)(unsigned long)p != p) { 696 r = -EFAULT; 697 break; 698 } 699 for (i = 0; i < d->nvqs; ++i) { 700 struct vhost_virtqueue *vq; 701 void __user *base = (void __user *)(unsigned long)p; 702 vq = d->vqs + i; 703 mutex_lock(&vq->mutex); 704 /* If ring is inactive, will check when it's enabled. */ 705 if (vq->private_data && !vq_log_access_ok(vq, base)) 706 r = -EFAULT; 707 else 708 vq->log_base = base; 709 mutex_unlock(&vq->mutex); 710 } 711 break; 712 case VHOST_SET_LOG_FD: 713 r = get_user(fd, (int __user *)argp); 714 if (r < 0) 715 break; 716 eventfp = fd == -1 ? NULL : eventfd_fget(fd); 717 if (IS_ERR(eventfp)) { 718 r = PTR_ERR(eventfp); 719 break; 720 } 721 if (eventfp != d->log_file) { 722 filep = d->log_file; 723 ctx = d->log_ctx; 724 d->log_ctx = eventfp ? 725 eventfd_ctx_fileget(eventfp) : NULL; 726 } else 727 filep = eventfp; 728 for (i = 0; i < d->nvqs; ++i) { 729 mutex_lock(&d->vqs[i].mutex); 730 d->vqs[i].log_ctx = d->log_ctx; 731 mutex_unlock(&d->vqs[i].mutex); 732 } 733 if (ctx) 734 eventfd_ctx_put(ctx); 735 if (filep) 736 fput(filep); 737 break; 738 default: 739 r = vhost_set_vring(d, ioctl, argp); 740 break; 741 } 742 done: 743 return r; 744 } 745 746 static const struct vhost_memory_region *find_region(struct vhost_memory *mem, 747 __u64 addr, __u32 len) 748 { 749 struct vhost_memory_region *reg; 750 int i; 751 /* linear search is not brilliant, but we really have on the order of 6 752 * regions in practice */ 753 for (i = 0; i < mem->nregions; ++i) { 754 reg = mem->regions + i; 755 if (reg->guest_phys_addr <= addr && 756 reg->guest_phys_addr + reg->memory_size - 1 >= addr) 757 return reg; 758 } 759 return NULL; 760 } 761 762 /* TODO: This is really inefficient. We need something like get_user() 763 * (instruction directly accesses the data, with an exception table entry 764 * returning -EFAULT). See Documentation/x86/exception-tables.txt. 765 */ 766 static int set_bit_to_user(int nr, void __user *addr) 767 { 768 unsigned long log = (unsigned long)addr; 769 struct page *page; 770 void *base; 771 int bit = nr + (log % PAGE_SIZE) * 8; 772 int r; 773 r = get_user_pages_fast(log, 1, 1, &page); 774 if (r < 0) 775 return r; 776 BUG_ON(r != 1); 777 base = kmap_atomic(page, KM_USER0); 778 set_bit(bit, base); 779 kunmap_atomic(base, KM_USER0); 780 set_page_dirty_lock(page); 781 put_page(page); 782 return 0; 783 } 784 785 static int log_write(void __user *log_base, 786 u64 write_address, u64 write_length) 787 { 788 int r; 789 if (!write_length) 790 return 0; 791 write_address /= VHOST_PAGE_SIZE; 792 for (;;) { 793 u64 base = (u64)(unsigned long)log_base; 794 u64 log = base + write_address / 8; 795 int bit = write_address % 8; 796 if ((u64)(unsigned long)log != log) 797 return -EFAULT; 798 r = set_bit_to_user(bit, (void __user *)(unsigned long)log); 799 if (r < 0) 800 return r; 801 if (write_length <= VHOST_PAGE_SIZE) 802 break; 803 write_length -= VHOST_PAGE_SIZE; 804 write_address += VHOST_PAGE_SIZE; 805 } 806 return r; 807 } 808 809 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log, 810 unsigned int log_num, u64 len) 811 { 812 int i, r; 813 814 /* Make sure data written is seen before log. */ 815 smp_wmb(); 816 for (i = 0; i < log_num; ++i) { 817 u64 l = min(log[i].len, len); 818 r = log_write(vq->log_base, log[i].addr, l); 819 if (r < 0) 820 return r; 821 len -= l; 822 if (!len) 823 return 0; 824 } 825 if (vq->log_ctx) 826 eventfd_signal(vq->log_ctx, 1); 827 /* Length written exceeds what we have stored. This is a bug. */ 828 BUG(); 829 return 0; 830 } 831 832 static int translate_desc(struct vhost_dev *dev, u64 addr, u32 len, 833 struct iovec iov[], int iov_size) 834 { 835 const struct vhost_memory_region *reg; 836 struct vhost_memory *mem; 837 struct iovec *_iov; 838 u64 s = 0; 839 int ret = 0; 840 841 rcu_read_lock(); 842 843 mem = rcu_dereference(dev->memory); 844 while ((u64)len > s) { 845 u64 size; 846 if (unlikely(ret >= iov_size)) { 847 ret = -ENOBUFS; 848 break; 849 } 850 reg = find_region(mem, addr, len); 851 if (unlikely(!reg)) { 852 ret = -EFAULT; 853 break; 854 } 855 _iov = iov + ret; 856 size = reg->memory_size - addr + reg->guest_phys_addr; 857 _iov->iov_len = min((u64)len, size); 858 _iov->iov_base = (void __user *)(unsigned long) 859 (reg->userspace_addr + addr - reg->guest_phys_addr); 860 s += size; 861 addr += size; 862 ++ret; 863 } 864 865 rcu_read_unlock(); 866 return ret; 867 } 868 869 /* Each buffer in the virtqueues is actually a chain of descriptors. This 870 * function returns the next descriptor in the chain, 871 * or -1U if we're at the end. */ 872 static unsigned next_desc(struct vring_desc *desc) 873 { 874 unsigned int next; 875 876 /* If this descriptor says it doesn't chain, we're done. */ 877 if (!(desc->flags & VRING_DESC_F_NEXT)) 878 return -1U; 879 880 /* Check they're not leading us off end of descriptors. */ 881 next = desc->next; 882 /* Make sure compiler knows to grab that: we don't want it changing! */ 883 /* We will use the result as an index in an array, so most 884 * architectures only need a compiler barrier here. */ 885 read_barrier_depends(); 886 887 return next; 888 } 889 890 static int get_indirect(struct vhost_dev *dev, struct vhost_virtqueue *vq, 891 struct iovec iov[], unsigned int iov_size, 892 unsigned int *out_num, unsigned int *in_num, 893 struct vhost_log *log, unsigned int *log_num, 894 struct vring_desc *indirect) 895 { 896 struct vring_desc desc; 897 unsigned int i = 0, count, found = 0; 898 int ret; 899 900 /* Sanity check */ 901 if (unlikely(indirect->len % sizeof desc)) { 902 vq_err(vq, "Invalid length in indirect descriptor: " 903 "len 0x%llx not multiple of 0x%zx\n", 904 (unsigned long long)indirect->len, 905 sizeof desc); 906 return -EINVAL; 907 } 908 909 ret = translate_desc(dev, indirect->addr, indirect->len, vq->indirect, 910 ARRAY_SIZE(vq->indirect)); 911 if (unlikely(ret < 0)) { 912 vq_err(vq, "Translation failure %d in indirect.\n", ret); 913 return ret; 914 } 915 916 /* We will use the result as an address to read from, so most 917 * architectures only need a compiler barrier here. */ 918 read_barrier_depends(); 919 920 count = indirect->len / sizeof desc; 921 /* Buffers are chained via a 16 bit next field, so 922 * we can have at most 2^16 of these. */ 923 if (unlikely(count > USHRT_MAX + 1)) { 924 vq_err(vq, "Indirect buffer length too big: %d\n", 925 indirect->len); 926 return -E2BIG; 927 } 928 929 do { 930 unsigned iov_count = *in_num + *out_num; 931 if (unlikely(++found > count)) { 932 vq_err(vq, "Loop detected: last one at %u " 933 "indirect size %u\n", 934 i, count); 935 return -EINVAL; 936 } 937 if (unlikely(memcpy_fromiovec((unsigned char *)&desc, vq->indirect, 938 sizeof desc))) { 939 vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n", 940 i, (size_t)indirect->addr + i * sizeof desc); 941 return -EINVAL; 942 } 943 if (unlikely(desc.flags & VRING_DESC_F_INDIRECT)) { 944 vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n", 945 i, (size_t)indirect->addr + i * sizeof desc); 946 return -EINVAL; 947 } 948 949 ret = translate_desc(dev, desc.addr, desc.len, iov + iov_count, 950 iov_size - iov_count); 951 if (unlikely(ret < 0)) { 952 vq_err(vq, "Translation failure %d indirect idx %d\n", 953 ret, i); 954 return ret; 955 } 956 /* If this is an input descriptor, increment that count. */ 957 if (desc.flags & VRING_DESC_F_WRITE) { 958 *in_num += ret; 959 if (unlikely(log)) { 960 log[*log_num].addr = desc.addr; 961 log[*log_num].len = desc.len; 962 ++*log_num; 963 } 964 } else { 965 /* If it's an output descriptor, they're all supposed 966 * to come before any input descriptors. */ 967 if (unlikely(*in_num)) { 968 vq_err(vq, "Indirect descriptor " 969 "has out after in: idx %d\n", i); 970 return -EINVAL; 971 } 972 *out_num += ret; 973 } 974 } while ((i = next_desc(&desc)) != -1); 975 return 0; 976 } 977 978 /* This looks in the virtqueue and for the first available buffer, and converts 979 * it to an iovec for convenient access. Since descriptors consist of some 980 * number of output then some number of input descriptors, it's actually two 981 * iovecs, but we pack them into one and note how many of each there were. 982 * 983 * This function returns the descriptor number found, or vq->num (which is 984 * never a valid descriptor number) if none was found. A negative code is 985 * returned on error. */ 986 int vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq, 987 struct iovec iov[], unsigned int iov_size, 988 unsigned int *out_num, unsigned int *in_num, 989 struct vhost_log *log, unsigned int *log_num) 990 { 991 struct vring_desc desc; 992 unsigned int i, head, found = 0; 993 u16 last_avail_idx; 994 int ret; 995 996 /* Check it isn't doing very strange things with descriptor numbers. */ 997 last_avail_idx = vq->last_avail_idx; 998 if (unlikely(get_user(vq->avail_idx, &vq->avail->idx))) { 999 vq_err(vq, "Failed to access avail idx at %p\n", 1000 &vq->avail->idx); 1001 return -EFAULT; 1002 } 1003 1004 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) { 1005 vq_err(vq, "Guest moved used index from %u to %u", 1006 last_avail_idx, vq->avail_idx); 1007 return -EFAULT; 1008 } 1009 1010 /* If there's nothing new since last we looked, return invalid. */ 1011 if (vq->avail_idx == last_avail_idx) 1012 return vq->num; 1013 1014 /* Only get avail ring entries after they have been exposed by guest. */ 1015 smp_rmb(); 1016 1017 /* Grab the next descriptor number they're advertising, and increment 1018 * the index we've seen. */ 1019 if (unlikely(get_user(head, 1020 &vq->avail->ring[last_avail_idx % vq->num]))) { 1021 vq_err(vq, "Failed to read head: idx %d address %p\n", 1022 last_avail_idx, 1023 &vq->avail->ring[last_avail_idx % vq->num]); 1024 return -EFAULT; 1025 } 1026 1027 /* If their number is silly, that's an error. */ 1028 if (unlikely(head >= vq->num)) { 1029 vq_err(vq, "Guest says index %u > %u is available", 1030 head, vq->num); 1031 return -EINVAL; 1032 } 1033 1034 /* When we start there are none of either input nor output. */ 1035 *out_num = *in_num = 0; 1036 if (unlikely(log)) 1037 *log_num = 0; 1038 1039 i = head; 1040 do { 1041 unsigned iov_count = *in_num + *out_num; 1042 if (unlikely(i >= vq->num)) { 1043 vq_err(vq, "Desc index is %u > %u, head = %u", 1044 i, vq->num, head); 1045 return -EINVAL; 1046 } 1047 if (unlikely(++found > vq->num)) { 1048 vq_err(vq, "Loop detected: last one at %u " 1049 "vq size %u head %u\n", 1050 i, vq->num, head); 1051 return -EINVAL; 1052 } 1053 ret = copy_from_user(&desc, vq->desc + i, sizeof desc); 1054 if (unlikely(ret)) { 1055 vq_err(vq, "Failed to get descriptor: idx %d addr %p\n", 1056 i, vq->desc + i); 1057 return -EFAULT; 1058 } 1059 if (desc.flags & VRING_DESC_F_INDIRECT) { 1060 ret = get_indirect(dev, vq, iov, iov_size, 1061 out_num, in_num, 1062 log, log_num, &desc); 1063 if (unlikely(ret < 0)) { 1064 vq_err(vq, "Failure detected " 1065 "in indirect descriptor at idx %d\n", i); 1066 return ret; 1067 } 1068 continue; 1069 } 1070 1071 ret = translate_desc(dev, desc.addr, desc.len, iov + iov_count, 1072 iov_size - iov_count); 1073 if (unlikely(ret < 0)) { 1074 vq_err(vq, "Translation failure %d descriptor idx %d\n", 1075 ret, i); 1076 return ret; 1077 } 1078 if (desc.flags & VRING_DESC_F_WRITE) { 1079 /* If this is an input descriptor, 1080 * increment that count. */ 1081 *in_num += ret; 1082 if (unlikely(log)) { 1083 log[*log_num].addr = desc.addr; 1084 log[*log_num].len = desc.len; 1085 ++*log_num; 1086 } 1087 } else { 1088 /* If it's an output descriptor, they're all supposed 1089 * to come before any input descriptors. */ 1090 if (unlikely(*in_num)) { 1091 vq_err(vq, "Descriptor has out after in: " 1092 "idx %d\n", i); 1093 return -EINVAL; 1094 } 1095 *out_num += ret; 1096 } 1097 } while ((i = next_desc(&desc)) != -1); 1098 1099 /* On success, increment avail index. */ 1100 vq->last_avail_idx++; 1101 return head; 1102 } 1103 1104 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */ 1105 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n) 1106 { 1107 vq->last_avail_idx -= n; 1108 } 1109 1110 /* After we've used one of their buffers, we tell them about it. We'll then 1111 * want to notify the guest, using eventfd. */ 1112 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len) 1113 { 1114 struct vring_used_elem __user *used; 1115 1116 /* The virtqueue contains a ring of used buffers. Get a pointer to the 1117 * next entry in that used ring. */ 1118 used = &vq->used->ring[vq->last_used_idx % vq->num]; 1119 if (put_user(head, &used->id)) { 1120 vq_err(vq, "Failed to write used id"); 1121 return -EFAULT; 1122 } 1123 if (put_user(len, &used->len)) { 1124 vq_err(vq, "Failed to write used len"); 1125 return -EFAULT; 1126 } 1127 /* Make sure buffer is written before we update index. */ 1128 smp_wmb(); 1129 if (put_user(vq->last_used_idx + 1, &vq->used->idx)) { 1130 vq_err(vq, "Failed to increment used idx"); 1131 return -EFAULT; 1132 } 1133 if (unlikely(vq->log_used)) { 1134 /* Make sure data is seen before log. */ 1135 smp_wmb(); 1136 /* Log used ring entry write. */ 1137 log_write(vq->log_base, 1138 vq->log_addr + 1139 ((void __user *)used - (void __user *)vq->used), 1140 sizeof *used); 1141 /* Log used index update. */ 1142 log_write(vq->log_base, 1143 vq->log_addr + offsetof(struct vring_used, idx), 1144 sizeof vq->used->idx); 1145 if (vq->log_ctx) 1146 eventfd_signal(vq->log_ctx, 1); 1147 } 1148 vq->last_used_idx++; 1149 return 0; 1150 } 1151 1152 static int __vhost_add_used_n(struct vhost_virtqueue *vq, 1153 struct vring_used_elem *heads, 1154 unsigned count) 1155 { 1156 struct vring_used_elem __user *used; 1157 int start; 1158 1159 start = vq->last_used_idx % vq->num; 1160 used = vq->used->ring + start; 1161 if (copy_to_user(used, heads, count * sizeof *used)) { 1162 vq_err(vq, "Failed to write used"); 1163 return -EFAULT; 1164 } 1165 if (unlikely(vq->log_used)) { 1166 /* Make sure data is seen before log. */ 1167 smp_wmb(); 1168 /* Log used ring entry write. */ 1169 log_write(vq->log_base, 1170 vq->log_addr + 1171 ((void __user *)used - (void __user *)vq->used), 1172 count * sizeof *used); 1173 } 1174 vq->last_used_idx += count; 1175 return 0; 1176 } 1177 1178 /* After we've used one of their buffers, we tell them about it. We'll then 1179 * want to notify the guest, using eventfd. */ 1180 int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads, 1181 unsigned count) 1182 { 1183 int start, n, r; 1184 1185 start = vq->last_used_idx % vq->num; 1186 n = vq->num - start; 1187 if (n < count) { 1188 r = __vhost_add_used_n(vq, heads, n); 1189 if (r < 0) 1190 return r; 1191 heads += n; 1192 count -= n; 1193 } 1194 r = __vhost_add_used_n(vq, heads, count); 1195 1196 /* Make sure buffer is written before we update index. */ 1197 smp_wmb(); 1198 if (put_user(vq->last_used_idx, &vq->used->idx)) { 1199 vq_err(vq, "Failed to increment used idx"); 1200 return -EFAULT; 1201 } 1202 if (unlikely(vq->log_used)) { 1203 /* Log used index update. */ 1204 log_write(vq->log_base, 1205 vq->log_addr + offsetof(struct vring_used, idx), 1206 sizeof vq->used->idx); 1207 if (vq->log_ctx) 1208 eventfd_signal(vq->log_ctx, 1); 1209 } 1210 return r; 1211 } 1212 1213 /* This actually signals the guest, using eventfd. */ 1214 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq) 1215 { 1216 __u16 flags; 1217 /* Flush out used index updates. This is paired 1218 * with the barrier that the Guest executes when enabling 1219 * interrupts. */ 1220 smp_mb(); 1221 1222 if (get_user(flags, &vq->avail->flags)) { 1223 vq_err(vq, "Failed to get flags"); 1224 return; 1225 } 1226 1227 /* If they don't want an interrupt, don't signal, unless empty. */ 1228 if ((flags & VRING_AVAIL_F_NO_INTERRUPT) && 1229 (vq->avail_idx != vq->last_avail_idx || 1230 !vhost_has_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY))) 1231 return; 1232 1233 /* Signal the Guest tell them we used something up. */ 1234 if (vq->call_ctx) 1235 eventfd_signal(vq->call_ctx, 1); 1236 } 1237 1238 /* And here's the combo meal deal. Supersize me! */ 1239 void vhost_add_used_and_signal(struct vhost_dev *dev, 1240 struct vhost_virtqueue *vq, 1241 unsigned int head, int len) 1242 { 1243 vhost_add_used(vq, head, len); 1244 vhost_signal(dev, vq); 1245 } 1246 1247 /* multi-buffer version of vhost_add_used_and_signal */ 1248 void vhost_add_used_and_signal_n(struct vhost_dev *dev, 1249 struct vhost_virtqueue *vq, 1250 struct vring_used_elem *heads, unsigned count) 1251 { 1252 vhost_add_used_n(vq, heads, count); 1253 vhost_signal(dev, vq); 1254 } 1255 1256 /* OK, now we need to know about added descriptors. */ 1257 bool vhost_enable_notify(struct vhost_virtqueue *vq) 1258 { 1259 u16 avail_idx; 1260 int r; 1261 if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY)) 1262 return false; 1263 vq->used_flags &= ~VRING_USED_F_NO_NOTIFY; 1264 r = put_user(vq->used_flags, &vq->used->flags); 1265 if (r) { 1266 vq_err(vq, "Failed to enable notification at %p: %d\n", 1267 &vq->used->flags, r); 1268 return false; 1269 } 1270 /* They could have slipped one in as we were doing that: make 1271 * sure it's written, then check again. */ 1272 smp_mb(); 1273 r = get_user(avail_idx, &vq->avail->idx); 1274 if (r) { 1275 vq_err(vq, "Failed to check avail idx at %p: %d\n", 1276 &vq->avail->idx, r); 1277 return false; 1278 } 1279 1280 return avail_idx != vq->avail_idx; 1281 } 1282 1283 /* We don't need to be notified again. */ 1284 void vhost_disable_notify(struct vhost_virtqueue *vq) 1285 { 1286 int r; 1287 if (vq->used_flags & VRING_USED_F_NO_NOTIFY) 1288 return; 1289 vq->used_flags |= VRING_USED_F_NO_NOTIFY; 1290 r = put_user(vq->used_flags, &vq->used->flags); 1291 if (r) 1292 vq_err(vq, "Failed to enable notification at %p: %d\n", 1293 &vq->used->flags, r); 1294 } 1295