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 26 #include <linux/net.h> 27 #include <linux/if_packet.h> 28 #include <linux/if_arp.h> 29 30 #include <net/sock.h> 31 32 #include "vhost.h" 33 34 enum { 35 VHOST_MEMORY_MAX_NREGIONS = 64, 36 VHOST_MEMORY_F_LOG = 0x1, 37 }; 38 39 static struct workqueue_struct *vhost_workqueue; 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; 55 poll = container_of(wait, struct vhost_poll, wait); 56 if (!((unsigned long)key & poll->mask)) 57 return 0; 58 59 queue_work(vhost_workqueue, &poll->work); 60 return 0; 61 } 62 63 /* Init poll structure */ 64 void vhost_poll_init(struct vhost_poll *poll, work_func_t func, 65 unsigned long mask) 66 { 67 INIT_WORK(&poll->work, func); 68 init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup); 69 init_poll_funcptr(&poll->table, vhost_poll_func); 70 poll->mask = mask; 71 } 72 73 /* Start polling a file. We add ourselves to file's wait queue. The caller must 74 * keep a reference to a file until after vhost_poll_stop is called. */ 75 void vhost_poll_start(struct vhost_poll *poll, struct file *file) 76 { 77 unsigned long mask; 78 mask = file->f_op->poll(file, &poll->table); 79 if (mask) 80 vhost_poll_wakeup(&poll->wait, 0, 0, (void *)mask); 81 } 82 83 /* Stop polling a file. After this function returns, it becomes safe to drop the 84 * file reference. You must also flush afterwards. */ 85 void vhost_poll_stop(struct vhost_poll *poll) 86 { 87 remove_wait_queue(poll->wqh, &poll->wait); 88 } 89 90 /* Flush any work that has been scheduled. When calling this, don't hold any 91 * locks that are also used by the callback. */ 92 void vhost_poll_flush(struct vhost_poll *poll) 93 { 94 flush_work(&poll->work); 95 } 96 97 void vhost_poll_queue(struct vhost_poll *poll) 98 { 99 queue_work(vhost_workqueue, &poll->work); 100 } 101 102 static void vhost_vq_reset(struct vhost_dev *dev, 103 struct vhost_virtqueue *vq) 104 { 105 vq->num = 1; 106 vq->desc = NULL; 107 vq->avail = NULL; 108 vq->used = NULL; 109 vq->last_avail_idx = 0; 110 vq->avail_idx = 0; 111 vq->last_used_idx = 0; 112 vq->used_flags = 0; 113 vq->used_flags = 0; 114 vq->log_used = false; 115 vq->log_addr = -1ull; 116 vq->hdr_size = 0; 117 vq->private_data = NULL; 118 vq->log_base = NULL; 119 vq->error_ctx = NULL; 120 vq->error = NULL; 121 vq->kick = NULL; 122 vq->call_ctx = NULL; 123 vq->call = NULL; 124 vq->log_ctx = NULL; 125 } 126 127 long vhost_dev_init(struct vhost_dev *dev, 128 struct vhost_virtqueue *vqs, int nvqs) 129 { 130 int i; 131 dev->vqs = vqs; 132 dev->nvqs = nvqs; 133 mutex_init(&dev->mutex); 134 dev->log_ctx = NULL; 135 dev->log_file = NULL; 136 dev->memory = NULL; 137 dev->mm = NULL; 138 139 for (i = 0; i < dev->nvqs; ++i) { 140 dev->vqs[i].dev = dev; 141 mutex_init(&dev->vqs[i].mutex); 142 vhost_vq_reset(dev, dev->vqs + i); 143 if (dev->vqs[i].handle_kick) 144 vhost_poll_init(&dev->vqs[i].poll, 145 dev->vqs[i].handle_kick, 146 POLLIN); 147 } 148 return 0; 149 } 150 151 /* Caller should have device mutex */ 152 long vhost_dev_check_owner(struct vhost_dev *dev) 153 { 154 /* Are you the owner? If not, I don't think you mean to do that */ 155 return dev->mm == current->mm ? 0 : -EPERM; 156 } 157 158 /* Caller should have device mutex */ 159 static long vhost_dev_set_owner(struct vhost_dev *dev) 160 { 161 /* Is there an owner already? */ 162 if (dev->mm) 163 return -EBUSY; 164 /* No owner, become one */ 165 dev->mm = get_task_mm(current); 166 return 0; 167 } 168 169 /* Caller should have device mutex */ 170 long vhost_dev_reset_owner(struct vhost_dev *dev) 171 { 172 struct vhost_memory *memory; 173 174 /* Restore memory to default empty mapping. */ 175 memory = kmalloc(offsetof(struct vhost_memory, regions), GFP_KERNEL); 176 if (!memory) 177 return -ENOMEM; 178 179 vhost_dev_cleanup(dev); 180 181 memory->nregions = 0; 182 dev->memory = memory; 183 return 0; 184 } 185 186 /* Caller should have device mutex */ 187 void vhost_dev_cleanup(struct vhost_dev *dev) 188 { 189 int i; 190 for (i = 0; i < dev->nvqs; ++i) { 191 if (dev->vqs[i].kick && dev->vqs[i].handle_kick) { 192 vhost_poll_stop(&dev->vqs[i].poll); 193 vhost_poll_flush(&dev->vqs[i].poll); 194 } 195 if (dev->vqs[i].error_ctx) 196 eventfd_ctx_put(dev->vqs[i].error_ctx); 197 if (dev->vqs[i].error) 198 fput(dev->vqs[i].error); 199 if (dev->vqs[i].kick) 200 fput(dev->vqs[i].kick); 201 if (dev->vqs[i].call_ctx) 202 eventfd_ctx_put(dev->vqs[i].call_ctx); 203 if (dev->vqs[i].call) 204 fput(dev->vqs[i].call); 205 vhost_vq_reset(dev, dev->vqs + i); 206 } 207 if (dev->log_ctx) 208 eventfd_ctx_put(dev->log_ctx); 209 dev->log_ctx = NULL; 210 if (dev->log_file) 211 fput(dev->log_file); 212 dev->log_file = NULL; 213 /* No one will access memory at this point */ 214 kfree(dev->memory); 215 dev->memory = NULL; 216 if (dev->mm) 217 mmput(dev->mm); 218 dev->mm = NULL; 219 } 220 221 static int log_access_ok(void __user *log_base, u64 addr, unsigned long sz) 222 { 223 u64 a = addr / VHOST_PAGE_SIZE / 8; 224 /* Make sure 64 bit math will not overflow. */ 225 if (a > ULONG_MAX - (unsigned long)log_base || 226 a + (unsigned long)log_base > ULONG_MAX) 227 return -EFAULT; 228 229 return access_ok(VERIFY_WRITE, log_base + a, 230 (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8); 231 } 232 233 /* Caller should have vq mutex and device mutex. */ 234 static int vq_memory_access_ok(void __user *log_base, struct vhost_memory *mem, 235 int log_all) 236 { 237 int i; 238 for (i = 0; i < mem->nregions; ++i) { 239 struct vhost_memory_region *m = mem->regions + i; 240 unsigned long a = m->userspace_addr; 241 if (m->memory_size > ULONG_MAX) 242 return 0; 243 else if (!access_ok(VERIFY_WRITE, (void __user *)a, 244 m->memory_size)) 245 return 0; 246 else if (log_all && !log_access_ok(log_base, 247 m->guest_phys_addr, 248 m->memory_size)) 249 return 0; 250 } 251 return 1; 252 } 253 254 /* Can we switch to this memory table? */ 255 /* Caller should have device mutex but not vq mutex */ 256 static int memory_access_ok(struct vhost_dev *d, struct vhost_memory *mem, 257 int log_all) 258 { 259 int i; 260 for (i = 0; i < d->nvqs; ++i) { 261 int ok; 262 mutex_lock(&d->vqs[i].mutex); 263 /* If ring is inactive, will check when it's enabled. */ 264 if (d->vqs[i].private_data) 265 ok = vq_memory_access_ok(d->vqs[i].log_base, mem, 266 log_all); 267 else 268 ok = 1; 269 mutex_unlock(&d->vqs[i].mutex); 270 if (!ok) 271 return 0; 272 } 273 return 1; 274 } 275 276 static int vq_access_ok(unsigned int num, 277 struct vring_desc __user *desc, 278 struct vring_avail __user *avail, 279 struct vring_used __user *used) 280 { 281 return access_ok(VERIFY_READ, desc, num * sizeof *desc) && 282 access_ok(VERIFY_READ, avail, 283 sizeof *avail + num * sizeof *avail->ring) && 284 access_ok(VERIFY_WRITE, used, 285 sizeof *used + num * sizeof *used->ring); 286 } 287 288 /* Can we log writes? */ 289 /* Caller should have device mutex but not vq mutex */ 290 int vhost_log_access_ok(struct vhost_dev *dev) 291 { 292 return memory_access_ok(dev, dev->memory, 1); 293 } 294 295 /* Verify access for write logging. */ 296 /* Caller should have vq mutex and device mutex */ 297 static int vq_log_access_ok(struct vhost_virtqueue *vq, void __user *log_base) 298 { 299 return vq_memory_access_ok(log_base, vq->dev->memory, 300 vhost_has_feature(vq->dev, VHOST_F_LOG_ALL)) && 301 (!vq->log_used || log_access_ok(log_base, vq->log_addr, 302 sizeof *vq->used + 303 vq->num * sizeof *vq->used->ring)); 304 } 305 306 /* Can we start vq? */ 307 /* Caller should have vq mutex and device mutex */ 308 int vhost_vq_access_ok(struct vhost_virtqueue *vq) 309 { 310 return vq_access_ok(vq->num, vq->desc, vq->avail, vq->used) && 311 vq_log_access_ok(vq, vq->log_base); 312 } 313 314 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m) 315 { 316 struct vhost_memory mem, *newmem, *oldmem; 317 unsigned long size = offsetof(struct vhost_memory, regions); 318 long r; 319 r = copy_from_user(&mem, m, size); 320 if (r) 321 return r; 322 if (mem.padding) 323 return -EOPNOTSUPP; 324 if (mem.nregions > VHOST_MEMORY_MAX_NREGIONS) 325 return -E2BIG; 326 newmem = kmalloc(size + mem.nregions * sizeof *m->regions, GFP_KERNEL); 327 if (!newmem) 328 return -ENOMEM; 329 330 memcpy(newmem, &mem, size); 331 r = copy_from_user(newmem->regions, m->regions, 332 mem.nregions * sizeof *m->regions); 333 if (r) { 334 kfree(newmem); 335 return r; 336 } 337 338 if (!memory_access_ok(d, newmem, vhost_has_feature(d, VHOST_F_LOG_ALL))) 339 return -EFAULT; 340 oldmem = d->memory; 341 rcu_assign_pointer(d->memory, newmem); 342 synchronize_rcu(); 343 kfree(oldmem); 344 return 0; 345 } 346 347 static int init_used(struct vhost_virtqueue *vq, 348 struct vring_used __user *used) 349 { 350 int r = put_user(vq->used_flags, &used->flags); 351 if (r) 352 return r; 353 return get_user(vq->last_used_idx, &used->idx); 354 } 355 356 static long vhost_set_vring(struct vhost_dev *d, int ioctl, void __user *argp) 357 { 358 struct file *eventfp, *filep = NULL, 359 *pollstart = NULL, *pollstop = NULL; 360 struct eventfd_ctx *ctx = NULL; 361 u32 __user *idxp = argp; 362 struct vhost_virtqueue *vq; 363 struct vhost_vring_state s; 364 struct vhost_vring_file f; 365 struct vhost_vring_addr a; 366 u32 idx; 367 long r; 368 369 r = get_user(idx, idxp); 370 if (r < 0) 371 return r; 372 if (idx > d->nvqs) 373 return -ENOBUFS; 374 375 vq = d->vqs + idx; 376 377 mutex_lock(&vq->mutex); 378 379 switch (ioctl) { 380 case VHOST_SET_VRING_NUM: 381 /* Resizing ring with an active backend? 382 * You don't want to do that. */ 383 if (vq->private_data) { 384 r = -EBUSY; 385 break; 386 } 387 r = copy_from_user(&s, argp, sizeof s); 388 if (r < 0) 389 break; 390 if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) { 391 r = -EINVAL; 392 break; 393 } 394 vq->num = s.num; 395 break; 396 case VHOST_SET_VRING_BASE: 397 /* Moving base with an active backend? 398 * You don't want to do that. */ 399 if (vq->private_data) { 400 r = -EBUSY; 401 break; 402 } 403 r = copy_from_user(&s, argp, sizeof s); 404 if (r < 0) 405 break; 406 if (s.num > 0xffff) { 407 r = -EINVAL; 408 break; 409 } 410 vq->last_avail_idx = s.num; 411 /* Forget the cached index value. */ 412 vq->avail_idx = vq->last_avail_idx; 413 break; 414 case VHOST_GET_VRING_BASE: 415 s.index = idx; 416 s.num = vq->last_avail_idx; 417 r = copy_to_user(argp, &s, sizeof s); 418 break; 419 case VHOST_SET_VRING_ADDR: 420 r = copy_from_user(&a, argp, sizeof a); 421 if (r < 0) 422 break; 423 if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) { 424 r = -EOPNOTSUPP; 425 break; 426 } 427 /* For 32bit, verify that the top 32bits of the user 428 data are set to zero. */ 429 if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr || 430 (u64)(unsigned long)a.used_user_addr != a.used_user_addr || 431 (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) { 432 r = -EFAULT; 433 break; 434 } 435 if ((a.avail_user_addr & (sizeof *vq->avail->ring - 1)) || 436 (a.used_user_addr & (sizeof *vq->used->ring - 1)) || 437 (a.log_guest_addr & (sizeof *vq->used->ring - 1))) { 438 r = -EINVAL; 439 break; 440 } 441 442 /* We only verify access here if backend is configured. 443 * If it is not, we don't as size might not have been setup. 444 * We will verify when backend is configured. */ 445 if (vq->private_data) { 446 if (!vq_access_ok(vq->num, 447 (void __user *)(unsigned long)a.desc_user_addr, 448 (void __user *)(unsigned long)a.avail_user_addr, 449 (void __user *)(unsigned long)a.used_user_addr)) { 450 r = -EINVAL; 451 break; 452 } 453 454 /* Also validate log access for used ring if enabled. */ 455 if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) && 456 !log_access_ok(vq->log_base, a.log_guest_addr, 457 sizeof *vq->used + 458 vq->num * sizeof *vq->used->ring)) { 459 r = -EINVAL; 460 break; 461 } 462 } 463 464 r = init_used(vq, (struct vring_used __user *)(unsigned long) 465 a.used_user_addr); 466 if (r) 467 break; 468 vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG)); 469 vq->desc = (void __user *)(unsigned long)a.desc_user_addr; 470 vq->avail = (void __user *)(unsigned long)a.avail_user_addr; 471 vq->log_addr = a.log_guest_addr; 472 vq->used = (void __user *)(unsigned long)a.used_user_addr; 473 break; 474 case VHOST_SET_VRING_KICK: 475 r = copy_from_user(&f, argp, sizeof f); 476 if (r < 0) 477 break; 478 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); 479 if (IS_ERR(eventfp)) 480 return PTR_ERR(eventfp); 481 if (eventfp != vq->kick) { 482 pollstop = filep = vq->kick; 483 pollstart = vq->kick = eventfp; 484 } else 485 filep = eventfp; 486 break; 487 case VHOST_SET_VRING_CALL: 488 r = copy_from_user(&f, argp, sizeof f); 489 if (r < 0) 490 break; 491 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); 492 if (IS_ERR(eventfp)) 493 return PTR_ERR(eventfp); 494 if (eventfp != vq->call) { 495 filep = vq->call; 496 ctx = vq->call_ctx; 497 vq->call = eventfp; 498 vq->call_ctx = eventfp ? 499 eventfd_ctx_fileget(eventfp) : NULL; 500 } else 501 filep = eventfp; 502 break; 503 case VHOST_SET_VRING_ERR: 504 r = copy_from_user(&f, argp, sizeof f); 505 if (r < 0) 506 break; 507 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); 508 if (IS_ERR(eventfp)) 509 return PTR_ERR(eventfp); 510 if (eventfp != vq->error) { 511 filep = vq->error; 512 vq->error = eventfp; 513 ctx = vq->error_ctx; 514 vq->error_ctx = eventfp ? 515 eventfd_ctx_fileget(eventfp) : NULL; 516 } else 517 filep = eventfp; 518 break; 519 default: 520 r = -ENOIOCTLCMD; 521 } 522 523 if (pollstop && vq->handle_kick) 524 vhost_poll_stop(&vq->poll); 525 526 if (ctx) 527 eventfd_ctx_put(ctx); 528 if (filep) 529 fput(filep); 530 531 if (pollstart && vq->handle_kick) 532 vhost_poll_start(&vq->poll, vq->kick); 533 534 mutex_unlock(&vq->mutex); 535 536 if (pollstop && vq->handle_kick) 537 vhost_poll_flush(&vq->poll); 538 return r; 539 } 540 541 /* Caller must have device mutex */ 542 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, unsigned long arg) 543 { 544 void __user *argp = (void __user *)arg; 545 struct file *eventfp, *filep = NULL; 546 struct eventfd_ctx *ctx = NULL; 547 u64 p; 548 long r; 549 int i, fd; 550 551 /* If you are not the owner, you can become one */ 552 if (ioctl == VHOST_SET_OWNER) { 553 r = vhost_dev_set_owner(d); 554 goto done; 555 } 556 557 /* You must be the owner to do anything else */ 558 r = vhost_dev_check_owner(d); 559 if (r) 560 goto done; 561 562 switch (ioctl) { 563 case VHOST_SET_MEM_TABLE: 564 r = vhost_set_memory(d, argp); 565 break; 566 case VHOST_SET_LOG_BASE: 567 r = copy_from_user(&p, argp, sizeof p); 568 if (r < 0) 569 break; 570 if ((u64)(unsigned long)p != p) { 571 r = -EFAULT; 572 break; 573 } 574 for (i = 0; i < d->nvqs; ++i) { 575 struct vhost_virtqueue *vq; 576 void __user *base = (void __user *)(unsigned long)p; 577 vq = d->vqs + i; 578 mutex_lock(&vq->mutex); 579 /* If ring is inactive, will check when it's enabled. */ 580 if (vq->private_data && !vq_log_access_ok(vq, base)) 581 r = -EFAULT; 582 else 583 vq->log_base = base; 584 mutex_unlock(&vq->mutex); 585 } 586 break; 587 case VHOST_SET_LOG_FD: 588 r = get_user(fd, (int __user *)argp); 589 if (r < 0) 590 break; 591 eventfp = fd == -1 ? NULL : eventfd_fget(fd); 592 if (IS_ERR(eventfp)) { 593 r = PTR_ERR(eventfp); 594 break; 595 } 596 if (eventfp != d->log_file) { 597 filep = d->log_file; 598 ctx = d->log_ctx; 599 d->log_ctx = eventfp ? 600 eventfd_ctx_fileget(eventfp) : NULL; 601 } else 602 filep = eventfp; 603 for (i = 0; i < d->nvqs; ++i) { 604 mutex_lock(&d->vqs[i].mutex); 605 d->vqs[i].log_ctx = d->log_ctx; 606 mutex_unlock(&d->vqs[i].mutex); 607 } 608 if (ctx) 609 eventfd_ctx_put(ctx); 610 if (filep) 611 fput(filep); 612 break; 613 default: 614 r = vhost_set_vring(d, ioctl, argp); 615 break; 616 } 617 done: 618 return r; 619 } 620 621 static const struct vhost_memory_region *find_region(struct vhost_memory *mem, 622 __u64 addr, __u32 len) 623 { 624 struct vhost_memory_region *reg; 625 int i; 626 /* linear search is not brilliant, but we really have on the order of 6 627 * regions in practice */ 628 for (i = 0; i < mem->nregions; ++i) { 629 reg = mem->regions + i; 630 if (reg->guest_phys_addr <= addr && 631 reg->guest_phys_addr + reg->memory_size - 1 >= addr) 632 return reg; 633 } 634 return NULL; 635 } 636 637 /* TODO: This is really inefficient. We need something like get_user() 638 * (instruction directly accesses the data, with an exception table entry 639 * returning -EFAULT). See Documentation/x86/exception-tables.txt. 640 */ 641 static int set_bit_to_user(int nr, void __user *addr) 642 { 643 unsigned long log = (unsigned long)addr; 644 struct page *page; 645 void *base; 646 int bit = nr + (log % PAGE_SIZE) * 8; 647 int r; 648 r = get_user_pages_fast(log, 1, 1, &page); 649 if (r < 0) 650 return r; 651 BUG_ON(r != 1); 652 base = kmap_atomic(page, KM_USER0); 653 set_bit(bit, base); 654 kunmap_atomic(base, KM_USER0); 655 set_page_dirty_lock(page); 656 put_page(page); 657 return 0; 658 } 659 660 static int log_write(void __user *log_base, 661 u64 write_address, u64 write_length) 662 { 663 int r; 664 if (!write_length) 665 return 0; 666 write_address /= VHOST_PAGE_SIZE; 667 for (;;) { 668 u64 base = (u64)(unsigned long)log_base; 669 u64 log = base + write_address / 8; 670 int bit = write_address % 8; 671 if ((u64)(unsigned long)log != log) 672 return -EFAULT; 673 r = set_bit_to_user(bit, (void __user *)(unsigned long)log); 674 if (r < 0) 675 return r; 676 if (write_length <= VHOST_PAGE_SIZE) 677 break; 678 write_length -= VHOST_PAGE_SIZE; 679 write_address += VHOST_PAGE_SIZE; 680 } 681 return r; 682 } 683 684 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log, 685 unsigned int log_num, u64 len) 686 { 687 int i, r; 688 689 /* Make sure data written is seen before log. */ 690 smp_wmb(); 691 for (i = 0; i < log_num; ++i) { 692 u64 l = min(log[i].len, len); 693 r = log_write(vq->log_base, log[i].addr, l); 694 if (r < 0) 695 return r; 696 len -= l; 697 if (!len) 698 return 0; 699 } 700 if (vq->log_ctx) 701 eventfd_signal(vq->log_ctx, 1); 702 /* Length written exceeds what we have stored. This is a bug. */ 703 BUG(); 704 return 0; 705 } 706 707 int translate_desc(struct vhost_dev *dev, u64 addr, u32 len, 708 struct iovec iov[], int iov_size) 709 { 710 const struct vhost_memory_region *reg; 711 struct vhost_memory *mem; 712 struct iovec *_iov; 713 u64 s = 0; 714 int ret = 0; 715 716 rcu_read_lock(); 717 718 mem = rcu_dereference(dev->memory); 719 while ((u64)len > s) { 720 u64 size; 721 if (ret >= iov_size) { 722 ret = -ENOBUFS; 723 break; 724 } 725 reg = find_region(mem, addr, len); 726 if (!reg) { 727 ret = -EFAULT; 728 break; 729 } 730 _iov = iov + ret; 731 size = reg->memory_size - addr + reg->guest_phys_addr; 732 _iov->iov_len = min((u64)len, size); 733 _iov->iov_base = (void *)(unsigned long) 734 (reg->userspace_addr + addr - reg->guest_phys_addr); 735 s += size; 736 addr += size; 737 ++ret; 738 } 739 740 rcu_read_unlock(); 741 return ret; 742 } 743 744 /* Each buffer in the virtqueues is actually a chain of descriptors. This 745 * function returns the next descriptor in the chain, 746 * or -1U if we're at the end. */ 747 static unsigned next_desc(struct vring_desc *desc) 748 { 749 unsigned int next; 750 751 /* If this descriptor says it doesn't chain, we're done. */ 752 if (!(desc->flags & VRING_DESC_F_NEXT)) 753 return -1U; 754 755 /* Check they're not leading us off end of descriptors. */ 756 next = desc->next; 757 /* Make sure compiler knows to grab that: we don't want it changing! */ 758 /* We will use the result as an index in an array, so most 759 * architectures only need a compiler barrier here. */ 760 read_barrier_depends(); 761 762 return next; 763 } 764 765 static unsigned get_indirect(struct vhost_dev *dev, struct vhost_virtqueue *vq, 766 struct iovec iov[], unsigned int iov_size, 767 unsigned int *out_num, unsigned int *in_num, 768 struct vhost_log *log, unsigned int *log_num, 769 struct vring_desc *indirect) 770 { 771 struct vring_desc desc; 772 unsigned int i = 0, count, found = 0; 773 int ret; 774 775 /* Sanity check */ 776 if (indirect->len % sizeof desc) { 777 vq_err(vq, "Invalid length in indirect descriptor: " 778 "len 0x%llx not multiple of 0x%zx\n", 779 (unsigned long long)indirect->len, 780 sizeof desc); 781 return -EINVAL; 782 } 783 784 ret = translate_desc(dev, indirect->addr, indirect->len, vq->indirect, 785 ARRAY_SIZE(vq->indirect)); 786 if (ret < 0) { 787 vq_err(vq, "Translation failure %d in indirect.\n", ret); 788 return ret; 789 } 790 791 /* We will use the result as an address to read from, so most 792 * architectures only need a compiler barrier here. */ 793 read_barrier_depends(); 794 795 count = indirect->len / sizeof desc; 796 /* Buffers are chained via a 16 bit next field, so 797 * we can have at most 2^16 of these. */ 798 if (count > USHORT_MAX + 1) { 799 vq_err(vq, "Indirect buffer length too big: %d\n", 800 indirect->len); 801 return -E2BIG; 802 } 803 804 do { 805 unsigned iov_count = *in_num + *out_num; 806 if (++found > count) { 807 vq_err(vq, "Loop detected: last one at %u " 808 "indirect size %u\n", 809 i, count); 810 return -EINVAL; 811 } 812 if (memcpy_fromiovec((unsigned char *)&desc, vq->indirect, 813 sizeof desc)) { 814 vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n", 815 i, (size_t)indirect->addr + i * sizeof desc); 816 return -EINVAL; 817 } 818 if (desc.flags & VRING_DESC_F_INDIRECT) { 819 vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n", 820 i, (size_t)indirect->addr + i * sizeof desc); 821 return -EINVAL; 822 } 823 824 ret = translate_desc(dev, desc.addr, desc.len, iov + iov_count, 825 iov_size - iov_count); 826 if (ret < 0) { 827 vq_err(vq, "Translation failure %d indirect idx %d\n", 828 ret, i); 829 return ret; 830 } 831 /* If this is an input descriptor, increment that count. */ 832 if (desc.flags & VRING_DESC_F_WRITE) { 833 *in_num += ret; 834 if (unlikely(log)) { 835 log[*log_num].addr = desc.addr; 836 log[*log_num].len = desc.len; 837 ++*log_num; 838 } 839 } else { 840 /* If it's an output descriptor, they're all supposed 841 * to come before any input descriptors. */ 842 if (*in_num) { 843 vq_err(vq, "Indirect descriptor " 844 "has out after in: idx %d\n", i); 845 return -EINVAL; 846 } 847 *out_num += ret; 848 } 849 } while ((i = next_desc(&desc)) != -1); 850 return 0; 851 } 852 853 /* This looks in the virtqueue and for the first available buffer, and converts 854 * it to an iovec for convenient access. Since descriptors consist of some 855 * number of output then some number of input descriptors, it's actually two 856 * iovecs, but we pack them into one and note how many of each there were. 857 * 858 * This function returns the descriptor number found, or vq->num (which 859 * is never a valid descriptor number) if none was found. */ 860 unsigned vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq, 861 struct iovec iov[], unsigned int iov_size, 862 unsigned int *out_num, unsigned int *in_num, 863 struct vhost_log *log, unsigned int *log_num) 864 { 865 struct vring_desc desc; 866 unsigned int i, head, found = 0; 867 u16 last_avail_idx; 868 int ret; 869 870 /* Check it isn't doing very strange things with descriptor numbers. */ 871 last_avail_idx = vq->last_avail_idx; 872 if (get_user(vq->avail_idx, &vq->avail->idx)) { 873 vq_err(vq, "Failed to access avail idx at %p\n", 874 &vq->avail->idx); 875 return vq->num; 876 } 877 878 if ((u16)(vq->avail_idx - last_avail_idx) > vq->num) { 879 vq_err(vq, "Guest moved used index from %u to %u", 880 last_avail_idx, vq->avail_idx); 881 return vq->num; 882 } 883 884 /* If there's nothing new since last we looked, return invalid. */ 885 if (vq->avail_idx == last_avail_idx) 886 return vq->num; 887 888 /* Only get avail ring entries after they have been exposed by guest. */ 889 smp_rmb(); 890 891 /* Grab the next descriptor number they're advertising, and increment 892 * the index we've seen. */ 893 if (get_user(head, &vq->avail->ring[last_avail_idx % vq->num])) { 894 vq_err(vq, "Failed to read head: idx %d address %p\n", 895 last_avail_idx, 896 &vq->avail->ring[last_avail_idx % vq->num]); 897 return vq->num; 898 } 899 900 /* If their number is silly, that's an error. */ 901 if (head >= vq->num) { 902 vq_err(vq, "Guest says index %u > %u is available", 903 head, vq->num); 904 return vq->num; 905 } 906 907 /* When we start there are none of either input nor output. */ 908 *out_num = *in_num = 0; 909 if (unlikely(log)) 910 *log_num = 0; 911 912 i = head; 913 do { 914 unsigned iov_count = *in_num + *out_num; 915 if (i >= vq->num) { 916 vq_err(vq, "Desc index is %u > %u, head = %u", 917 i, vq->num, head); 918 return vq->num; 919 } 920 if (++found > vq->num) { 921 vq_err(vq, "Loop detected: last one at %u " 922 "vq size %u head %u\n", 923 i, vq->num, head); 924 return vq->num; 925 } 926 ret = copy_from_user(&desc, vq->desc + i, sizeof desc); 927 if (ret) { 928 vq_err(vq, "Failed to get descriptor: idx %d addr %p\n", 929 i, vq->desc + i); 930 return vq->num; 931 } 932 if (desc.flags & VRING_DESC_F_INDIRECT) { 933 ret = get_indirect(dev, vq, iov, iov_size, 934 out_num, in_num, 935 log, log_num, &desc); 936 if (ret < 0) { 937 vq_err(vq, "Failure detected " 938 "in indirect descriptor at idx %d\n", i); 939 return vq->num; 940 } 941 continue; 942 } 943 944 ret = translate_desc(dev, desc.addr, desc.len, iov + iov_count, 945 iov_size - iov_count); 946 if (ret < 0) { 947 vq_err(vq, "Translation failure %d descriptor idx %d\n", 948 ret, i); 949 return vq->num; 950 } 951 if (desc.flags & VRING_DESC_F_WRITE) { 952 /* If this is an input descriptor, 953 * increment that count. */ 954 *in_num += ret; 955 if (unlikely(log)) { 956 log[*log_num].addr = desc.addr; 957 log[*log_num].len = desc.len; 958 ++*log_num; 959 } 960 } else { 961 /* If it's an output descriptor, they're all supposed 962 * to come before any input descriptors. */ 963 if (*in_num) { 964 vq_err(vq, "Descriptor has out after in: " 965 "idx %d\n", i); 966 return vq->num; 967 } 968 *out_num += ret; 969 } 970 } while ((i = next_desc(&desc)) != -1); 971 972 /* On success, increment avail index. */ 973 vq->last_avail_idx++; 974 return head; 975 } 976 977 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */ 978 void vhost_discard_vq_desc(struct vhost_virtqueue *vq) 979 { 980 vq->last_avail_idx--; 981 } 982 983 /* After we've used one of their buffers, we tell them about it. We'll then 984 * want to notify the guest, using eventfd. */ 985 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len) 986 { 987 struct vring_used_elem *used; 988 989 /* The virtqueue contains a ring of used buffers. Get a pointer to the 990 * next entry in that used ring. */ 991 used = &vq->used->ring[vq->last_used_idx % vq->num]; 992 if (put_user(head, &used->id)) { 993 vq_err(vq, "Failed to write used id"); 994 return -EFAULT; 995 } 996 if (put_user(len, &used->len)) { 997 vq_err(vq, "Failed to write used len"); 998 return -EFAULT; 999 } 1000 /* Make sure buffer is written before we update index. */ 1001 smp_wmb(); 1002 if (put_user(vq->last_used_idx + 1, &vq->used->idx)) { 1003 vq_err(vq, "Failed to increment used idx"); 1004 return -EFAULT; 1005 } 1006 if (unlikely(vq->log_used)) { 1007 /* Make sure data is seen before log. */ 1008 smp_wmb(); 1009 /* Log used ring entry write. */ 1010 log_write(vq->log_base, 1011 vq->log_addr + ((void *)used - (void *)vq->used), 1012 sizeof *used); 1013 /* Log used index update. */ 1014 log_write(vq->log_base, 1015 vq->log_addr + offsetof(struct vring_used, idx), 1016 sizeof vq->used->idx); 1017 if (vq->log_ctx) 1018 eventfd_signal(vq->log_ctx, 1); 1019 } 1020 vq->last_used_idx++; 1021 return 0; 1022 } 1023 1024 /* This actually signals the guest, using eventfd. */ 1025 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq) 1026 { 1027 __u16 flags = 0; 1028 if (get_user(flags, &vq->avail->flags)) { 1029 vq_err(vq, "Failed to get flags"); 1030 return; 1031 } 1032 1033 /* If they don't want an interrupt, don't signal, unless empty. */ 1034 if ((flags & VRING_AVAIL_F_NO_INTERRUPT) && 1035 (vq->avail_idx != vq->last_avail_idx || 1036 !vhost_has_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY))) 1037 return; 1038 1039 /* Signal the Guest tell them we used something up. */ 1040 if (vq->call_ctx) 1041 eventfd_signal(vq->call_ctx, 1); 1042 } 1043 1044 /* And here's the combo meal deal. Supersize me! */ 1045 void vhost_add_used_and_signal(struct vhost_dev *dev, 1046 struct vhost_virtqueue *vq, 1047 unsigned int head, int len) 1048 { 1049 vhost_add_used(vq, head, len); 1050 vhost_signal(dev, vq); 1051 } 1052 1053 /* OK, now we need to know about added descriptors. */ 1054 bool vhost_enable_notify(struct vhost_virtqueue *vq) 1055 { 1056 u16 avail_idx; 1057 int r; 1058 if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY)) 1059 return false; 1060 vq->used_flags &= ~VRING_USED_F_NO_NOTIFY; 1061 r = put_user(vq->used_flags, &vq->used->flags); 1062 if (r) { 1063 vq_err(vq, "Failed to enable notification at %p: %d\n", 1064 &vq->used->flags, r); 1065 return false; 1066 } 1067 /* They could have slipped one in as we were doing that: make 1068 * sure it's written, then check again. */ 1069 smp_mb(); 1070 r = get_user(avail_idx, &vq->avail->idx); 1071 if (r) { 1072 vq_err(vq, "Failed to check avail idx at %p: %d\n", 1073 &vq->avail->idx, r); 1074 return false; 1075 } 1076 1077 return avail_idx != vq->last_avail_idx; 1078 } 1079 1080 /* We don't need to be notified again. */ 1081 void vhost_disable_notify(struct vhost_virtqueue *vq) 1082 { 1083 int r; 1084 if (vq->used_flags & VRING_USED_F_NO_NOTIFY) 1085 return; 1086 vq->used_flags |= VRING_USED_F_NO_NOTIFY; 1087 r = put_user(vq->used_flags, &vq->used->flags); 1088 if (r) 1089 vq_err(vq, "Failed to enable notification at %p: %d\n", 1090 &vq->used->flags, r); 1091 } 1092 1093 int vhost_init(void) 1094 { 1095 vhost_workqueue = create_singlethread_workqueue("vhost"); 1096 if (!vhost_workqueue) 1097 return -ENOMEM; 1098 return 0; 1099 } 1100 1101 void vhost_cleanup(void) 1102 { 1103 destroy_workqueue(vhost_workqueue); 1104 } 1105