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/workqueue.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 27 #include <linux/net.h> 28 #include <linux/if_packet.h> 29 #include <linux/if_arp.h> 30 31 #include <net/sock.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 struct workqueue_struct *vhost_workqueue; 41 42 static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh, 43 poll_table *pt) 44 { 45 struct vhost_poll *poll; 46 poll = container_of(pt, struct vhost_poll, table); 47 48 poll->wqh = wqh; 49 add_wait_queue(wqh, &poll->wait); 50 } 51 52 static int vhost_poll_wakeup(wait_queue_t *wait, unsigned mode, int sync, 53 void *key) 54 { 55 struct vhost_poll *poll; 56 poll = container_of(wait, struct vhost_poll, wait); 57 if (!((unsigned long)key & poll->mask)) 58 return 0; 59 60 queue_work(vhost_workqueue, &poll->work); 61 return 0; 62 } 63 64 /* Init poll structure */ 65 void vhost_poll_init(struct vhost_poll *poll, work_func_t func, 66 unsigned long mask) 67 { 68 INIT_WORK(&poll->work, func); 69 init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup); 70 init_poll_funcptr(&poll->table, vhost_poll_func); 71 poll->mask = mask; 72 } 73 74 /* Start polling a file. We add ourselves to file's wait queue. The caller must 75 * keep a reference to a file until after vhost_poll_stop is called. */ 76 void vhost_poll_start(struct vhost_poll *poll, struct file *file) 77 { 78 unsigned long mask; 79 mask = file->f_op->poll(file, &poll->table); 80 if (mask) 81 vhost_poll_wakeup(&poll->wait, 0, 0, (void *)mask); 82 } 83 84 /* Stop polling a file. After this function returns, it becomes safe to drop the 85 * file reference. You must also flush afterwards. */ 86 void vhost_poll_stop(struct vhost_poll *poll) 87 { 88 remove_wait_queue(poll->wqh, &poll->wait); 89 } 90 91 /* Flush any work that has been scheduled. When calling this, don't hold any 92 * locks that are also used by the callback. */ 93 void vhost_poll_flush(struct vhost_poll *poll) 94 { 95 flush_work(&poll->work); 96 } 97 98 void vhost_poll_queue(struct vhost_poll *poll) 99 { 100 queue_work(vhost_workqueue, &poll->work); 101 } 102 103 static void vhost_vq_reset(struct vhost_dev *dev, 104 struct vhost_virtqueue *vq) 105 { 106 vq->num = 1; 107 vq->desc = NULL; 108 vq->avail = NULL; 109 vq->used = NULL; 110 vq->last_avail_idx = 0; 111 vq->avail_idx = 0; 112 vq->last_used_idx = 0; 113 vq->used_flags = 0; 114 vq->used_flags = 0; 115 vq->log_used = false; 116 vq->log_addr = -1ull; 117 vq->hdr_size = 0; 118 vq->private_data = NULL; 119 vq->log_base = NULL; 120 vq->error_ctx = NULL; 121 vq->error = NULL; 122 vq->kick = NULL; 123 vq->call_ctx = NULL; 124 vq->call = NULL; 125 vq->log_ctx = NULL; 126 } 127 128 long vhost_dev_init(struct vhost_dev *dev, 129 struct vhost_virtqueue *vqs, int nvqs) 130 { 131 int i; 132 dev->vqs = vqs; 133 dev->nvqs = nvqs; 134 mutex_init(&dev->mutex); 135 dev->log_ctx = NULL; 136 dev->log_file = NULL; 137 dev->memory = NULL; 138 dev->mm = NULL; 139 140 for (i = 0; i < dev->nvqs; ++i) { 141 dev->vqs[i].dev = dev; 142 mutex_init(&dev->vqs[i].mutex); 143 vhost_vq_reset(dev, dev->vqs + i); 144 if (dev->vqs[i].handle_kick) 145 vhost_poll_init(&dev->vqs[i].poll, 146 dev->vqs[i].handle_kick, 147 POLLIN); 148 } 149 return 0; 150 } 151 152 /* Caller should have device mutex */ 153 long vhost_dev_check_owner(struct vhost_dev *dev) 154 { 155 /* Are you the owner? If not, I don't think you mean to do that */ 156 return dev->mm == current->mm ? 0 : -EPERM; 157 } 158 159 /* Caller should have device mutex */ 160 static long vhost_dev_set_owner(struct vhost_dev *dev) 161 { 162 /* Is there an owner already? */ 163 if (dev->mm) 164 return -EBUSY; 165 /* No owner, become one */ 166 dev->mm = get_task_mm(current); 167 return 0; 168 } 169 170 /* Caller should have device mutex */ 171 long vhost_dev_reset_owner(struct vhost_dev *dev) 172 { 173 struct vhost_memory *memory; 174 175 /* Restore memory to default empty mapping. */ 176 memory = kmalloc(offsetof(struct vhost_memory, regions), GFP_KERNEL); 177 if (!memory) 178 return -ENOMEM; 179 180 vhost_dev_cleanup(dev); 181 182 memory->nregions = 0; 183 dev->memory = memory; 184 return 0; 185 } 186 187 /* Caller should have device mutex */ 188 void vhost_dev_cleanup(struct vhost_dev *dev) 189 { 190 int i; 191 for (i = 0; i < dev->nvqs; ++i) { 192 if (dev->vqs[i].kick && dev->vqs[i].handle_kick) { 193 vhost_poll_stop(&dev->vqs[i].poll); 194 vhost_poll_flush(&dev->vqs[i].poll); 195 } 196 if (dev->vqs[i].error_ctx) 197 eventfd_ctx_put(dev->vqs[i].error_ctx); 198 if (dev->vqs[i].error) 199 fput(dev->vqs[i].error); 200 if (dev->vqs[i].kick) 201 fput(dev->vqs[i].kick); 202 if (dev->vqs[i].call_ctx) 203 eventfd_ctx_put(dev->vqs[i].call_ctx); 204 if (dev->vqs[i].call) 205 fput(dev->vqs[i].call); 206 vhost_vq_reset(dev, dev->vqs + i); 207 } 208 if (dev->log_ctx) 209 eventfd_ctx_put(dev->log_ctx); 210 dev->log_ctx = NULL; 211 if (dev->log_file) 212 fput(dev->log_file); 213 dev->log_file = NULL; 214 /* No one will access memory at this point */ 215 kfree(dev->memory); 216 dev->memory = NULL; 217 if (dev->mm) 218 mmput(dev->mm); 219 dev->mm = NULL; 220 } 221 222 static int log_access_ok(void __user *log_base, u64 addr, unsigned long sz) 223 { 224 u64 a = addr / VHOST_PAGE_SIZE / 8; 225 /* Make sure 64 bit math will not overflow. */ 226 if (a > ULONG_MAX - (unsigned long)log_base || 227 a + (unsigned long)log_base > ULONG_MAX) 228 return -EFAULT; 229 230 return access_ok(VERIFY_WRITE, log_base + a, 231 (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8); 232 } 233 234 /* Caller should have vq mutex and device mutex. */ 235 static int vq_memory_access_ok(void __user *log_base, struct vhost_memory *mem, 236 int log_all) 237 { 238 int i; 239 240 if (!mem) 241 return 0; 242 243 for (i = 0; i < mem->nregions; ++i) { 244 struct vhost_memory_region *m = mem->regions + i; 245 unsigned long a = m->userspace_addr; 246 if (m->memory_size > ULONG_MAX) 247 return 0; 248 else if (!access_ok(VERIFY_WRITE, (void __user *)a, 249 m->memory_size)) 250 return 0; 251 else if (log_all && !log_access_ok(log_base, 252 m->guest_phys_addr, 253 m->memory_size)) 254 return 0; 255 } 256 return 1; 257 } 258 259 /* Can we switch to this memory table? */ 260 /* Caller should have device mutex but not vq mutex */ 261 static int memory_access_ok(struct vhost_dev *d, struct vhost_memory *mem, 262 int log_all) 263 { 264 int i; 265 for (i = 0; i < d->nvqs; ++i) { 266 int ok; 267 mutex_lock(&d->vqs[i].mutex); 268 /* If ring is inactive, will check when it's enabled. */ 269 if (d->vqs[i].private_data) 270 ok = vq_memory_access_ok(d->vqs[i].log_base, mem, 271 log_all); 272 else 273 ok = 1; 274 mutex_unlock(&d->vqs[i].mutex); 275 if (!ok) 276 return 0; 277 } 278 return 1; 279 } 280 281 static int vq_access_ok(unsigned int num, 282 struct vring_desc __user *desc, 283 struct vring_avail __user *avail, 284 struct vring_used __user *used) 285 { 286 return access_ok(VERIFY_READ, desc, num * sizeof *desc) && 287 access_ok(VERIFY_READ, avail, 288 sizeof *avail + num * sizeof *avail->ring) && 289 access_ok(VERIFY_WRITE, used, 290 sizeof *used + num * sizeof *used->ring); 291 } 292 293 /* Can we log writes? */ 294 /* Caller should have device mutex but not vq mutex */ 295 int vhost_log_access_ok(struct vhost_dev *dev) 296 { 297 return memory_access_ok(dev, dev->memory, 1); 298 } 299 300 /* Verify access for write logging. */ 301 /* Caller should have vq mutex and device mutex */ 302 static int vq_log_access_ok(struct vhost_virtqueue *vq, void __user *log_base) 303 { 304 return vq_memory_access_ok(log_base, vq->dev->memory, 305 vhost_has_feature(vq->dev, VHOST_F_LOG_ALL)) && 306 (!vq->log_used || log_access_ok(log_base, vq->log_addr, 307 sizeof *vq->used + 308 vq->num * sizeof *vq->used->ring)); 309 } 310 311 /* Can we start vq? */ 312 /* Caller should have vq mutex and device mutex */ 313 int vhost_vq_access_ok(struct vhost_virtqueue *vq) 314 { 315 return vq_access_ok(vq->num, vq->desc, vq->avail, vq->used) && 316 vq_log_access_ok(vq, vq->log_base); 317 } 318 319 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m) 320 { 321 struct vhost_memory mem, *newmem, *oldmem; 322 unsigned long size = offsetof(struct vhost_memory, regions); 323 long r; 324 r = copy_from_user(&mem, m, size); 325 if (r) 326 return r; 327 if (mem.padding) 328 return -EOPNOTSUPP; 329 if (mem.nregions > VHOST_MEMORY_MAX_NREGIONS) 330 return -E2BIG; 331 newmem = kmalloc(size + mem.nregions * sizeof *m->regions, GFP_KERNEL); 332 if (!newmem) 333 return -ENOMEM; 334 335 memcpy(newmem, &mem, size); 336 r = copy_from_user(newmem->regions, m->regions, 337 mem.nregions * sizeof *m->regions); 338 if (r) { 339 kfree(newmem); 340 return r; 341 } 342 343 if (!memory_access_ok(d, newmem, vhost_has_feature(d, VHOST_F_LOG_ALL))) 344 return -EFAULT; 345 oldmem = d->memory; 346 rcu_assign_pointer(d->memory, newmem); 347 synchronize_rcu(); 348 kfree(oldmem); 349 return 0; 350 } 351 352 static int init_used(struct vhost_virtqueue *vq, 353 struct vring_used __user *used) 354 { 355 int r = put_user(vq->used_flags, &used->flags); 356 if (r) 357 return r; 358 return get_user(vq->last_used_idx, &used->idx); 359 } 360 361 static long vhost_set_vring(struct vhost_dev *d, int ioctl, void __user *argp) 362 { 363 struct file *eventfp, *filep = NULL, 364 *pollstart = NULL, *pollstop = NULL; 365 struct eventfd_ctx *ctx = NULL; 366 u32 __user *idxp = argp; 367 struct vhost_virtqueue *vq; 368 struct vhost_vring_state s; 369 struct vhost_vring_file f; 370 struct vhost_vring_addr a; 371 u32 idx; 372 long r; 373 374 r = get_user(idx, idxp); 375 if (r < 0) 376 return r; 377 if (idx > d->nvqs) 378 return -ENOBUFS; 379 380 vq = d->vqs + idx; 381 382 mutex_lock(&vq->mutex); 383 384 switch (ioctl) { 385 case VHOST_SET_VRING_NUM: 386 /* Resizing ring with an active backend? 387 * You don't want to do that. */ 388 if (vq->private_data) { 389 r = -EBUSY; 390 break; 391 } 392 r = copy_from_user(&s, argp, sizeof s); 393 if (r < 0) 394 break; 395 if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) { 396 r = -EINVAL; 397 break; 398 } 399 vq->num = s.num; 400 break; 401 case VHOST_SET_VRING_BASE: 402 /* Moving base with an active backend? 403 * You don't want to do that. */ 404 if (vq->private_data) { 405 r = -EBUSY; 406 break; 407 } 408 r = copy_from_user(&s, argp, sizeof s); 409 if (r < 0) 410 break; 411 if (s.num > 0xffff) { 412 r = -EINVAL; 413 break; 414 } 415 vq->last_avail_idx = s.num; 416 /* Forget the cached index value. */ 417 vq->avail_idx = vq->last_avail_idx; 418 break; 419 case VHOST_GET_VRING_BASE: 420 s.index = idx; 421 s.num = vq->last_avail_idx; 422 r = copy_to_user(argp, &s, sizeof s); 423 break; 424 case VHOST_SET_VRING_ADDR: 425 r = copy_from_user(&a, argp, sizeof a); 426 if (r < 0) 427 break; 428 if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) { 429 r = -EOPNOTSUPP; 430 break; 431 } 432 /* For 32bit, verify that the top 32bits of the user 433 data are set to zero. */ 434 if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr || 435 (u64)(unsigned long)a.used_user_addr != a.used_user_addr || 436 (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) { 437 r = -EFAULT; 438 break; 439 } 440 if ((a.avail_user_addr & (sizeof *vq->avail->ring - 1)) || 441 (a.used_user_addr & (sizeof *vq->used->ring - 1)) || 442 (a.log_guest_addr & (sizeof *vq->used->ring - 1))) { 443 r = -EINVAL; 444 break; 445 } 446 447 /* We only verify access here if backend is configured. 448 * If it is not, we don't as size might not have been setup. 449 * We will verify when backend is configured. */ 450 if (vq->private_data) { 451 if (!vq_access_ok(vq->num, 452 (void __user *)(unsigned long)a.desc_user_addr, 453 (void __user *)(unsigned long)a.avail_user_addr, 454 (void __user *)(unsigned long)a.used_user_addr)) { 455 r = -EINVAL; 456 break; 457 } 458 459 /* Also validate log access for used ring if enabled. */ 460 if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) && 461 !log_access_ok(vq->log_base, a.log_guest_addr, 462 sizeof *vq->used + 463 vq->num * sizeof *vq->used->ring)) { 464 r = -EINVAL; 465 break; 466 } 467 } 468 469 r = init_used(vq, (struct vring_used __user *)(unsigned long) 470 a.used_user_addr); 471 if (r) 472 break; 473 vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG)); 474 vq->desc = (void __user *)(unsigned long)a.desc_user_addr; 475 vq->avail = (void __user *)(unsigned long)a.avail_user_addr; 476 vq->log_addr = a.log_guest_addr; 477 vq->used = (void __user *)(unsigned long)a.used_user_addr; 478 break; 479 case VHOST_SET_VRING_KICK: 480 r = copy_from_user(&f, argp, sizeof f); 481 if (r < 0) 482 break; 483 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); 484 if (IS_ERR(eventfp)) { 485 r = PTR_ERR(eventfp); 486 break; 487 } 488 if (eventfp != vq->kick) { 489 pollstop = filep = vq->kick; 490 pollstart = vq->kick = eventfp; 491 } else 492 filep = eventfp; 493 break; 494 case VHOST_SET_VRING_CALL: 495 r = copy_from_user(&f, argp, sizeof f); 496 if (r < 0) 497 break; 498 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); 499 if (IS_ERR(eventfp)) { 500 r = PTR_ERR(eventfp); 501 break; 502 } 503 if (eventfp != vq->call) { 504 filep = vq->call; 505 ctx = vq->call_ctx; 506 vq->call = eventfp; 507 vq->call_ctx = eventfp ? 508 eventfd_ctx_fileget(eventfp) : NULL; 509 } else 510 filep = eventfp; 511 break; 512 case VHOST_SET_VRING_ERR: 513 r = copy_from_user(&f, argp, sizeof f); 514 if (r < 0) 515 break; 516 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); 517 if (IS_ERR(eventfp)) { 518 r = PTR_ERR(eventfp); 519 break; 520 } 521 if (eventfp != vq->error) { 522 filep = vq->error; 523 vq->error = eventfp; 524 ctx = vq->error_ctx; 525 vq->error_ctx = eventfp ? 526 eventfd_ctx_fileget(eventfp) : NULL; 527 } else 528 filep = eventfp; 529 break; 530 default: 531 r = -ENOIOCTLCMD; 532 } 533 534 if (pollstop && vq->handle_kick) 535 vhost_poll_stop(&vq->poll); 536 537 if (ctx) 538 eventfd_ctx_put(ctx); 539 if (filep) 540 fput(filep); 541 542 if (pollstart && vq->handle_kick) 543 vhost_poll_start(&vq->poll, vq->kick); 544 545 mutex_unlock(&vq->mutex); 546 547 if (pollstop && vq->handle_kick) 548 vhost_poll_flush(&vq->poll); 549 return r; 550 } 551 552 /* Caller must have device mutex */ 553 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, unsigned long arg) 554 { 555 void __user *argp = (void __user *)arg; 556 struct file *eventfp, *filep = NULL; 557 struct eventfd_ctx *ctx = NULL; 558 u64 p; 559 long r; 560 int i, fd; 561 562 /* If you are not the owner, you can become one */ 563 if (ioctl == VHOST_SET_OWNER) { 564 r = vhost_dev_set_owner(d); 565 goto done; 566 } 567 568 /* You must be the owner to do anything else */ 569 r = vhost_dev_check_owner(d); 570 if (r) 571 goto done; 572 573 switch (ioctl) { 574 case VHOST_SET_MEM_TABLE: 575 r = vhost_set_memory(d, argp); 576 break; 577 case VHOST_SET_LOG_BASE: 578 r = copy_from_user(&p, argp, sizeof p); 579 if (r < 0) 580 break; 581 if ((u64)(unsigned long)p != p) { 582 r = -EFAULT; 583 break; 584 } 585 for (i = 0; i < d->nvqs; ++i) { 586 struct vhost_virtqueue *vq; 587 void __user *base = (void __user *)(unsigned long)p; 588 vq = d->vqs + i; 589 mutex_lock(&vq->mutex); 590 /* If ring is inactive, will check when it's enabled. */ 591 if (vq->private_data && !vq_log_access_ok(vq, base)) 592 r = -EFAULT; 593 else 594 vq->log_base = base; 595 mutex_unlock(&vq->mutex); 596 } 597 break; 598 case VHOST_SET_LOG_FD: 599 r = get_user(fd, (int __user *)argp); 600 if (r < 0) 601 break; 602 eventfp = fd == -1 ? NULL : eventfd_fget(fd); 603 if (IS_ERR(eventfp)) { 604 r = PTR_ERR(eventfp); 605 break; 606 } 607 if (eventfp != d->log_file) { 608 filep = d->log_file; 609 ctx = d->log_ctx; 610 d->log_ctx = eventfp ? 611 eventfd_ctx_fileget(eventfp) : NULL; 612 } else 613 filep = eventfp; 614 for (i = 0; i < d->nvqs; ++i) { 615 mutex_lock(&d->vqs[i].mutex); 616 d->vqs[i].log_ctx = d->log_ctx; 617 mutex_unlock(&d->vqs[i].mutex); 618 } 619 if (ctx) 620 eventfd_ctx_put(ctx); 621 if (filep) 622 fput(filep); 623 break; 624 default: 625 r = vhost_set_vring(d, ioctl, argp); 626 break; 627 } 628 done: 629 return r; 630 } 631 632 static const struct vhost_memory_region *find_region(struct vhost_memory *mem, 633 __u64 addr, __u32 len) 634 { 635 struct vhost_memory_region *reg; 636 int i; 637 /* linear search is not brilliant, but we really have on the order of 6 638 * regions in practice */ 639 for (i = 0; i < mem->nregions; ++i) { 640 reg = mem->regions + i; 641 if (reg->guest_phys_addr <= addr && 642 reg->guest_phys_addr + reg->memory_size - 1 >= addr) 643 return reg; 644 } 645 return NULL; 646 } 647 648 /* TODO: This is really inefficient. We need something like get_user() 649 * (instruction directly accesses the data, with an exception table entry 650 * returning -EFAULT). See Documentation/x86/exception-tables.txt. 651 */ 652 static int set_bit_to_user(int nr, void __user *addr) 653 { 654 unsigned long log = (unsigned long)addr; 655 struct page *page; 656 void *base; 657 int bit = nr + (log % PAGE_SIZE) * 8; 658 int r; 659 r = get_user_pages_fast(log, 1, 1, &page); 660 if (r < 0) 661 return r; 662 BUG_ON(r != 1); 663 base = kmap_atomic(page, KM_USER0); 664 set_bit(bit, base); 665 kunmap_atomic(base, KM_USER0); 666 set_page_dirty_lock(page); 667 put_page(page); 668 return 0; 669 } 670 671 static int log_write(void __user *log_base, 672 u64 write_address, u64 write_length) 673 { 674 int r; 675 if (!write_length) 676 return 0; 677 write_address /= VHOST_PAGE_SIZE; 678 for (;;) { 679 u64 base = (u64)(unsigned long)log_base; 680 u64 log = base + write_address / 8; 681 int bit = write_address % 8; 682 if ((u64)(unsigned long)log != log) 683 return -EFAULT; 684 r = set_bit_to_user(bit, (void __user *)(unsigned long)log); 685 if (r < 0) 686 return r; 687 if (write_length <= VHOST_PAGE_SIZE) 688 break; 689 write_length -= VHOST_PAGE_SIZE; 690 write_address += VHOST_PAGE_SIZE; 691 } 692 return r; 693 } 694 695 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log, 696 unsigned int log_num, u64 len) 697 { 698 int i, r; 699 700 /* Make sure data written is seen before log. */ 701 smp_wmb(); 702 for (i = 0; i < log_num; ++i) { 703 u64 l = min(log[i].len, len); 704 r = log_write(vq->log_base, log[i].addr, l); 705 if (r < 0) 706 return r; 707 len -= l; 708 if (!len) 709 return 0; 710 } 711 if (vq->log_ctx) 712 eventfd_signal(vq->log_ctx, 1); 713 /* Length written exceeds what we have stored. This is a bug. */ 714 BUG(); 715 return 0; 716 } 717 718 int translate_desc(struct vhost_dev *dev, u64 addr, u32 len, 719 struct iovec iov[], int iov_size) 720 { 721 const struct vhost_memory_region *reg; 722 struct vhost_memory *mem; 723 struct iovec *_iov; 724 u64 s = 0; 725 int ret = 0; 726 727 rcu_read_lock(); 728 729 mem = rcu_dereference(dev->memory); 730 while ((u64)len > s) { 731 u64 size; 732 if (ret >= iov_size) { 733 ret = -ENOBUFS; 734 break; 735 } 736 reg = find_region(mem, addr, len); 737 if (!reg) { 738 ret = -EFAULT; 739 break; 740 } 741 _iov = iov + ret; 742 size = reg->memory_size - addr + reg->guest_phys_addr; 743 _iov->iov_len = min((u64)len, size); 744 _iov->iov_base = (void *)(unsigned long) 745 (reg->userspace_addr + addr - reg->guest_phys_addr); 746 s += size; 747 addr += size; 748 ++ret; 749 } 750 751 rcu_read_unlock(); 752 return ret; 753 } 754 755 /* Each buffer in the virtqueues is actually a chain of descriptors. This 756 * function returns the next descriptor in the chain, 757 * or -1U if we're at the end. */ 758 static unsigned next_desc(struct vring_desc *desc) 759 { 760 unsigned int next; 761 762 /* If this descriptor says it doesn't chain, we're done. */ 763 if (!(desc->flags & VRING_DESC_F_NEXT)) 764 return -1U; 765 766 /* Check they're not leading us off end of descriptors. */ 767 next = desc->next; 768 /* Make sure compiler knows to grab that: we don't want it changing! */ 769 /* We will use the result as an index in an array, so most 770 * architectures only need a compiler barrier here. */ 771 read_barrier_depends(); 772 773 return next; 774 } 775 776 static unsigned get_indirect(struct vhost_dev *dev, struct vhost_virtqueue *vq, 777 struct iovec iov[], unsigned int iov_size, 778 unsigned int *out_num, unsigned int *in_num, 779 struct vhost_log *log, unsigned int *log_num, 780 struct vring_desc *indirect) 781 { 782 struct vring_desc desc; 783 unsigned int i = 0, count, found = 0; 784 int ret; 785 786 /* Sanity check */ 787 if (indirect->len % sizeof desc) { 788 vq_err(vq, "Invalid length in indirect descriptor: " 789 "len 0x%llx not multiple of 0x%zx\n", 790 (unsigned long long)indirect->len, 791 sizeof desc); 792 return -EINVAL; 793 } 794 795 ret = translate_desc(dev, indirect->addr, indirect->len, vq->indirect, 796 ARRAY_SIZE(vq->indirect)); 797 if (ret < 0) { 798 vq_err(vq, "Translation failure %d in indirect.\n", ret); 799 return ret; 800 } 801 802 /* We will use the result as an address to read from, so most 803 * architectures only need a compiler barrier here. */ 804 read_barrier_depends(); 805 806 count = indirect->len / sizeof desc; 807 /* Buffers are chained via a 16 bit next field, so 808 * we can have at most 2^16 of these. */ 809 if (count > USHORT_MAX + 1) { 810 vq_err(vq, "Indirect buffer length too big: %d\n", 811 indirect->len); 812 return -E2BIG; 813 } 814 815 do { 816 unsigned iov_count = *in_num + *out_num; 817 if (++found > count) { 818 vq_err(vq, "Loop detected: last one at %u " 819 "indirect size %u\n", 820 i, count); 821 return -EINVAL; 822 } 823 if (memcpy_fromiovec((unsigned char *)&desc, vq->indirect, 824 sizeof desc)) { 825 vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n", 826 i, (size_t)indirect->addr + i * sizeof desc); 827 return -EINVAL; 828 } 829 if (desc.flags & VRING_DESC_F_INDIRECT) { 830 vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n", 831 i, (size_t)indirect->addr + i * sizeof desc); 832 return -EINVAL; 833 } 834 835 ret = translate_desc(dev, desc.addr, desc.len, iov + iov_count, 836 iov_size - iov_count); 837 if (ret < 0) { 838 vq_err(vq, "Translation failure %d indirect idx %d\n", 839 ret, i); 840 return ret; 841 } 842 /* If this is an input descriptor, increment that count. */ 843 if (desc.flags & VRING_DESC_F_WRITE) { 844 *in_num += ret; 845 if (unlikely(log)) { 846 log[*log_num].addr = desc.addr; 847 log[*log_num].len = desc.len; 848 ++*log_num; 849 } 850 } else { 851 /* If it's an output descriptor, they're all supposed 852 * to come before any input descriptors. */ 853 if (*in_num) { 854 vq_err(vq, "Indirect descriptor " 855 "has out after in: idx %d\n", i); 856 return -EINVAL; 857 } 858 *out_num += ret; 859 } 860 } while ((i = next_desc(&desc)) != -1); 861 return 0; 862 } 863 864 /* This looks in the virtqueue and for the first available buffer, and converts 865 * it to an iovec for convenient access. Since descriptors consist of some 866 * number of output then some number of input descriptors, it's actually two 867 * iovecs, but we pack them into one and note how many of each there were. 868 * 869 * This function returns the descriptor number found, or vq->num (which 870 * is never a valid descriptor number) if none was found. */ 871 unsigned vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq, 872 struct iovec iov[], unsigned int iov_size, 873 unsigned int *out_num, unsigned int *in_num, 874 struct vhost_log *log, unsigned int *log_num) 875 { 876 struct vring_desc desc; 877 unsigned int i, head, found = 0; 878 u16 last_avail_idx; 879 int ret; 880 881 /* Check it isn't doing very strange things with descriptor numbers. */ 882 last_avail_idx = vq->last_avail_idx; 883 if (get_user(vq->avail_idx, &vq->avail->idx)) { 884 vq_err(vq, "Failed to access avail idx at %p\n", 885 &vq->avail->idx); 886 return vq->num; 887 } 888 889 if ((u16)(vq->avail_idx - last_avail_idx) > vq->num) { 890 vq_err(vq, "Guest moved used index from %u to %u", 891 last_avail_idx, vq->avail_idx); 892 return vq->num; 893 } 894 895 /* If there's nothing new since last we looked, return invalid. */ 896 if (vq->avail_idx == last_avail_idx) 897 return vq->num; 898 899 /* Only get avail ring entries after they have been exposed by guest. */ 900 smp_rmb(); 901 902 /* Grab the next descriptor number they're advertising, and increment 903 * the index we've seen. */ 904 if (get_user(head, &vq->avail->ring[last_avail_idx % vq->num])) { 905 vq_err(vq, "Failed to read head: idx %d address %p\n", 906 last_avail_idx, 907 &vq->avail->ring[last_avail_idx % vq->num]); 908 return vq->num; 909 } 910 911 /* If their number is silly, that's an error. */ 912 if (head >= vq->num) { 913 vq_err(vq, "Guest says index %u > %u is available", 914 head, vq->num); 915 return vq->num; 916 } 917 918 /* When we start there are none of either input nor output. */ 919 *out_num = *in_num = 0; 920 if (unlikely(log)) 921 *log_num = 0; 922 923 i = head; 924 do { 925 unsigned iov_count = *in_num + *out_num; 926 if (i >= vq->num) { 927 vq_err(vq, "Desc index is %u > %u, head = %u", 928 i, vq->num, head); 929 return vq->num; 930 } 931 if (++found > vq->num) { 932 vq_err(vq, "Loop detected: last one at %u " 933 "vq size %u head %u\n", 934 i, vq->num, head); 935 return vq->num; 936 } 937 ret = copy_from_user(&desc, vq->desc + i, sizeof desc); 938 if (ret) { 939 vq_err(vq, "Failed to get descriptor: idx %d addr %p\n", 940 i, vq->desc + i); 941 return vq->num; 942 } 943 if (desc.flags & VRING_DESC_F_INDIRECT) { 944 ret = get_indirect(dev, vq, iov, iov_size, 945 out_num, in_num, 946 log, log_num, &desc); 947 if (ret < 0) { 948 vq_err(vq, "Failure detected " 949 "in indirect descriptor at idx %d\n", i); 950 return vq->num; 951 } 952 continue; 953 } 954 955 ret = translate_desc(dev, desc.addr, desc.len, iov + iov_count, 956 iov_size - iov_count); 957 if (ret < 0) { 958 vq_err(vq, "Translation failure %d descriptor idx %d\n", 959 ret, i); 960 return vq->num; 961 } 962 if (desc.flags & VRING_DESC_F_WRITE) { 963 /* If this is an input descriptor, 964 * increment that count. */ 965 *in_num += ret; 966 if (unlikely(log)) { 967 log[*log_num].addr = desc.addr; 968 log[*log_num].len = desc.len; 969 ++*log_num; 970 } 971 } else { 972 /* If it's an output descriptor, they're all supposed 973 * to come before any input descriptors. */ 974 if (*in_num) { 975 vq_err(vq, "Descriptor has out after in: " 976 "idx %d\n", i); 977 return vq->num; 978 } 979 *out_num += ret; 980 } 981 } while ((i = next_desc(&desc)) != -1); 982 983 /* On success, increment avail index. */ 984 vq->last_avail_idx++; 985 return head; 986 } 987 988 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */ 989 void vhost_discard_vq_desc(struct vhost_virtqueue *vq) 990 { 991 vq->last_avail_idx--; 992 } 993 994 /* After we've used one of their buffers, we tell them about it. We'll then 995 * want to notify the guest, using eventfd. */ 996 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len) 997 { 998 struct vring_used_elem *used; 999 1000 /* The virtqueue contains a ring of used buffers. Get a pointer to the 1001 * next entry in that used ring. */ 1002 used = &vq->used->ring[vq->last_used_idx % vq->num]; 1003 if (put_user(head, &used->id)) { 1004 vq_err(vq, "Failed to write used id"); 1005 return -EFAULT; 1006 } 1007 if (put_user(len, &used->len)) { 1008 vq_err(vq, "Failed to write used len"); 1009 return -EFAULT; 1010 } 1011 /* Make sure buffer is written before we update index. */ 1012 smp_wmb(); 1013 if (put_user(vq->last_used_idx + 1, &vq->used->idx)) { 1014 vq_err(vq, "Failed to increment used idx"); 1015 return -EFAULT; 1016 } 1017 if (unlikely(vq->log_used)) { 1018 /* Make sure data is seen before log. */ 1019 smp_wmb(); 1020 /* Log used ring entry write. */ 1021 log_write(vq->log_base, 1022 vq->log_addr + ((void *)used - (void *)vq->used), 1023 sizeof *used); 1024 /* Log used index update. */ 1025 log_write(vq->log_base, 1026 vq->log_addr + offsetof(struct vring_used, idx), 1027 sizeof vq->used->idx); 1028 if (vq->log_ctx) 1029 eventfd_signal(vq->log_ctx, 1); 1030 } 1031 vq->last_used_idx++; 1032 return 0; 1033 } 1034 1035 /* This actually signals the guest, using eventfd. */ 1036 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq) 1037 { 1038 __u16 flags = 0; 1039 if (get_user(flags, &vq->avail->flags)) { 1040 vq_err(vq, "Failed to get flags"); 1041 return; 1042 } 1043 1044 /* If they don't want an interrupt, don't signal, unless empty. */ 1045 if ((flags & VRING_AVAIL_F_NO_INTERRUPT) && 1046 (vq->avail_idx != vq->last_avail_idx || 1047 !vhost_has_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY))) 1048 return; 1049 1050 /* Signal the Guest tell them we used something up. */ 1051 if (vq->call_ctx) 1052 eventfd_signal(vq->call_ctx, 1); 1053 } 1054 1055 /* And here's the combo meal deal. Supersize me! */ 1056 void vhost_add_used_and_signal(struct vhost_dev *dev, 1057 struct vhost_virtqueue *vq, 1058 unsigned int head, int len) 1059 { 1060 vhost_add_used(vq, head, len); 1061 vhost_signal(dev, vq); 1062 } 1063 1064 /* OK, now we need to know about added descriptors. */ 1065 bool vhost_enable_notify(struct vhost_virtqueue *vq) 1066 { 1067 u16 avail_idx; 1068 int r; 1069 if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY)) 1070 return false; 1071 vq->used_flags &= ~VRING_USED_F_NO_NOTIFY; 1072 r = put_user(vq->used_flags, &vq->used->flags); 1073 if (r) { 1074 vq_err(vq, "Failed to enable notification at %p: %d\n", 1075 &vq->used->flags, r); 1076 return false; 1077 } 1078 /* They could have slipped one in as we were doing that: make 1079 * sure it's written, then check again. */ 1080 smp_mb(); 1081 r = get_user(avail_idx, &vq->avail->idx); 1082 if (r) { 1083 vq_err(vq, "Failed to check avail idx at %p: %d\n", 1084 &vq->avail->idx, r); 1085 return false; 1086 } 1087 1088 return avail_idx != vq->last_avail_idx; 1089 } 1090 1091 /* We don't need to be notified again. */ 1092 void vhost_disable_notify(struct vhost_virtqueue *vq) 1093 { 1094 int r; 1095 if (vq->used_flags & VRING_USED_F_NO_NOTIFY) 1096 return; 1097 vq->used_flags |= VRING_USED_F_NO_NOTIFY; 1098 r = put_user(vq->used_flags, &vq->used->flags); 1099 if (r) 1100 vq_err(vq, "Failed to enable notification at %p: %d\n", 1101 &vq->used->flags, r); 1102 } 1103 1104 int vhost_init(void) 1105 { 1106 vhost_workqueue = create_singlethread_workqueue("vhost"); 1107 if (!vhost_workqueue) 1108 return -ENOMEM; 1109 return 0; 1110 } 1111 1112 void vhost_cleanup(void) 1113 { 1114 destroy_workqueue(vhost_workqueue); 1115 } 1116