1 /* Copyright (C) 2009 Red Hat, Inc. 2 * Copyright (C) 2006 Rusty Russell IBM Corporation 3 * 4 * Author: Michael S. Tsirkin <mst@redhat.com> 5 * 6 * Inspiration, some code, and most witty comments come from 7 * Documentation/virtual/lguest/lguest.c, by Rusty Russell 8 * 9 * This work is licensed under the terms of the GNU GPL, version 2. 10 * 11 * Generic code for virtio server in host kernel. 12 */ 13 14 #include <linux/eventfd.h> 15 #include <linux/vhost.h> 16 #include <linux/uio.h> 17 #include <linux/mm.h> 18 #include <linux/mmu_context.h> 19 #include <linux/miscdevice.h> 20 #include <linux/mutex.h> 21 #include <linux/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 #include <linux/module.h> 28 29 #include "vhost.h" 30 31 enum { 32 VHOST_MEMORY_MAX_NREGIONS = 64, 33 VHOST_MEMORY_F_LOG = 0x1, 34 }; 35 36 #define vhost_used_event(vq) ((__virtio16 __user *)&vq->avail->ring[vq->num]) 37 #define vhost_avail_event(vq) ((__virtio16 __user *)&vq->used->ring[vq->num]) 38 39 static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh, 40 poll_table *pt) 41 { 42 struct vhost_poll *poll; 43 44 poll = container_of(pt, struct vhost_poll, table); 45 poll->wqh = wqh; 46 add_wait_queue(wqh, &poll->wait); 47 } 48 49 static int vhost_poll_wakeup(wait_queue_t *wait, unsigned mode, int sync, 50 void *key) 51 { 52 struct vhost_poll *poll = container_of(wait, struct vhost_poll, wait); 53 54 if (!((unsigned long)key & poll->mask)) 55 return 0; 56 57 vhost_poll_queue(poll); 58 return 0; 59 } 60 61 void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn) 62 { 63 INIT_LIST_HEAD(&work->node); 64 work->fn = fn; 65 init_waitqueue_head(&work->done); 66 work->flushing = 0; 67 work->queue_seq = work->done_seq = 0; 68 } 69 EXPORT_SYMBOL_GPL(vhost_work_init); 70 71 /* Init poll structure */ 72 void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn, 73 unsigned long mask, struct vhost_dev *dev) 74 { 75 init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup); 76 init_poll_funcptr(&poll->table, vhost_poll_func); 77 poll->mask = mask; 78 poll->dev = dev; 79 poll->wqh = NULL; 80 81 vhost_work_init(&poll->work, fn); 82 } 83 EXPORT_SYMBOL_GPL(vhost_poll_init); 84 85 /* Start polling a file. We add ourselves to file's wait queue. The caller must 86 * keep a reference to a file until after vhost_poll_stop is called. */ 87 int vhost_poll_start(struct vhost_poll *poll, struct file *file) 88 { 89 unsigned long mask; 90 int ret = 0; 91 92 if (poll->wqh) 93 return 0; 94 95 mask = file->f_op->poll(file, &poll->table); 96 if (mask) 97 vhost_poll_wakeup(&poll->wait, 0, 0, (void *)mask); 98 if (mask & POLLERR) { 99 if (poll->wqh) 100 remove_wait_queue(poll->wqh, &poll->wait); 101 ret = -EINVAL; 102 } 103 104 return ret; 105 } 106 EXPORT_SYMBOL_GPL(vhost_poll_start); 107 108 /* Stop polling a file. After this function returns, it becomes safe to drop the 109 * file reference. You must also flush afterwards. */ 110 void vhost_poll_stop(struct vhost_poll *poll) 111 { 112 if (poll->wqh) { 113 remove_wait_queue(poll->wqh, &poll->wait); 114 poll->wqh = NULL; 115 } 116 } 117 EXPORT_SYMBOL_GPL(vhost_poll_stop); 118 119 static bool vhost_work_seq_done(struct vhost_dev *dev, struct vhost_work *work, 120 unsigned seq) 121 { 122 int left; 123 124 spin_lock_irq(&dev->work_lock); 125 left = seq - work->done_seq; 126 spin_unlock_irq(&dev->work_lock); 127 return left <= 0; 128 } 129 130 void vhost_work_flush(struct vhost_dev *dev, struct vhost_work *work) 131 { 132 unsigned seq; 133 int flushing; 134 135 spin_lock_irq(&dev->work_lock); 136 seq = work->queue_seq; 137 work->flushing++; 138 spin_unlock_irq(&dev->work_lock); 139 wait_event(work->done, vhost_work_seq_done(dev, work, seq)); 140 spin_lock_irq(&dev->work_lock); 141 flushing = --work->flushing; 142 spin_unlock_irq(&dev->work_lock); 143 BUG_ON(flushing < 0); 144 } 145 EXPORT_SYMBOL_GPL(vhost_work_flush); 146 147 /* Flush any work that has been scheduled. When calling this, don't hold any 148 * locks that are also used by the callback. */ 149 void vhost_poll_flush(struct vhost_poll *poll) 150 { 151 vhost_work_flush(poll->dev, &poll->work); 152 } 153 EXPORT_SYMBOL_GPL(vhost_poll_flush); 154 155 void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work) 156 { 157 unsigned long flags; 158 159 spin_lock_irqsave(&dev->work_lock, flags); 160 if (list_empty(&work->node)) { 161 list_add_tail(&work->node, &dev->work_list); 162 work->queue_seq++; 163 spin_unlock_irqrestore(&dev->work_lock, flags); 164 wake_up_process(dev->worker); 165 } else { 166 spin_unlock_irqrestore(&dev->work_lock, flags); 167 } 168 } 169 EXPORT_SYMBOL_GPL(vhost_work_queue); 170 171 void vhost_poll_queue(struct vhost_poll *poll) 172 { 173 vhost_work_queue(poll->dev, &poll->work); 174 } 175 EXPORT_SYMBOL_GPL(vhost_poll_queue); 176 177 static void vhost_vq_reset(struct vhost_dev *dev, 178 struct vhost_virtqueue *vq) 179 { 180 vq->num = 1; 181 vq->desc = NULL; 182 vq->avail = NULL; 183 vq->used = NULL; 184 vq->last_avail_idx = 0; 185 vq->avail_idx = 0; 186 vq->last_used_idx = 0; 187 vq->signalled_used = 0; 188 vq->signalled_used_valid = false; 189 vq->used_flags = 0; 190 vq->log_used = false; 191 vq->log_addr = -1ull; 192 vq->private_data = NULL; 193 vq->acked_features = 0; 194 vq->log_base = NULL; 195 vq->error_ctx = NULL; 196 vq->error = NULL; 197 vq->kick = NULL; 198 vq->call_ctx = NULL; 199 vq->call = NULL; 200 vq->log_ctx = NULL; 201 vq->memory = NULL; 202 } 203 204 static int vhost_worker(void *data) 205 { 206 struct vhost_dev *dev = data; 207 struct vhost_work *work = NULL; 208 unsigned uninitialized_var(seq); 209 mm_segment_t oldfs = get_fs(); 210 211 set_fs(USER_DS); 212 use_mm(dev->mm); 213 214 for (;;) { 215 /* mb paired w/ kthread_stop */ 216 set_current_state(TASK_INTERRUPTIBLE); 217 218 spin_lock_irq(&dev->work_lock); 219 if (work) { 220 work->done_seq = seq; 221 if (work->flushing) 222 wake_up_all(&work->done); 223 } 224 225 if (kthread_should_stop()) { 226 spin_unlock_irq(&dev->work_lock); 227 __set_current_state(TASK_RUNNING); 228 break; 229 } 230 if (!list_empty(&dev->work_list)) { 231 work = list_first_entry(&dev->work_list, 232 struct vhost_work, node); 233 list_del_init(&work->node); 234 seq = work->queue_seq; 235 } else 236 work = NULL; 237 spin_unlock_irq(&dev->work_lock); 238 239 if (work) { 240 __set_current_state(TASK_RUNNING); 241 work->fn(work); 242 if (need_resched()) 243 schedule(); 244 } else 245 schedule(); 246 247 } 248 unuse_mm(dev->mm); 249 set_fs(oldfs); 250 return 0; 251 } 252 253 static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq) 254 { 255 kfree(vq->indirect); 256 vq->indirect = NULL; 257 kfree(vq->log); 258 vq->log = NULL; 259 kfree(vq->heads); 260 vq->heads = NULL; 261 } 262 263 /* Helper to allocate iovec buffers for all vqs. */ 264 static long vhost_dev_alloc_iovecs(struct vhost_dev *dev) 265 { 266 struct vhost_virtqueue *vq; 267 int i; 268 269 for (i = 0; i < dev->nvqs; ++i) { 270 vq = dev->vqs[i]; 271 vq->indirect = kmalloc(sizeof *vq->indirect * UIO_MAXIOV, 272 GFP_KERNEL); 273 vq->log = kmalloc(sizeof *vq->log * UIO_MAXIOV, GFP_KERNEL); 274 vq->heads = kmalloc(sizeof *vq->heads * UIO_MAXIOV, GFP_KERNEL); 275 if (!vq->indirect || !vq->log || !vq->heads) 276 goto err_nomem; 277 } 278 return 0; 279 280 err_nomem: 281 for (; i >= 0; --i) 282 vhost_vq_free_iovecs(dev->vqs[i]); 283 return -ENOMEM; 284 } 285 286 static void vhost_dev_free_iovecs(struct vhost_dev *dev) 287 { 288 int i; 289 290 for (i = 0; i < dev->nvqs; ++i) 291 vhost_vq_free_iovecs(dev->vqs[i]); 292 } 293 294 void vhost_dev_init(struct vhost_dev *dev, 295 struct vhost_virtqueue **vqs, int nvqs) 296 { 297 struct vhost_virtqueue *vq; 298 int i; 299 300 dev->vqs = vqs; 301 dev->nvqs = nvqs; 302 mutex_init(&dev->mutex); 303 dev->log_ctx = NULL; 304 dev->log_file = NULL; 305 dev->memory = NULL; 306 dev->mm = NULL; 307 spin_lock_init(&dev->work_lock); 308 INIT_LIST_HEAD(&dev->work_list); 309 dev->worker = NULL; 310 311 for (i = 0; i < dev->nvqs; ++i) { 312 vq = dev->vqs[i]; 313 vq->log = NULL; 314 vq->indirect = NULL; 315 vq->heads = NULL; 316 vq->dev = dev; 317 mutex_init(&vq->mutex); 318 vhost_vq_reset(dev, vq); 319 if (vq->handle_kick) 320 vhost_poll_init(&vq->poll, vq->handle_kick, 321 POLLIN, dev); 322 } 323 } 324 EXPORT_SYMBOL_GPL(vhost_dev_init); 325 326 /* Caller should have device mutex */ 327 long vhost_dev_check_owner(struct vhost_dev *dev) 328 { 329 /* Are you the owner? If not, I don't think you mean to do that */ 330 return dev->mm == current->mm ? 0 : -EPERM; 331 } 332 EXPORT_SYMBOL_GPL(vhost_dev_check_owner); 333 334 struct vhost_attach_cgroups_struct { 335 struct vhost_work work; 336 struct task_struct *owner; 337 int ret; 338 }; 339 340 static void vhost_attach_cgroups_work(struct vhost_work *work) 341 { 342 struct vhost_attach_cgroups_struct *s; 343 344 s = container_of(work, struct vhost_attach_cgroups_struct, work); 345 s->ret = cgroup_attach_task_all(s->owner, current); 346 } 347 348 static int vhost_attach_cgroups(struct vhost_dev *dev) 349 { 350 struct vhost_attach_cgroups_struct attach; 351 352 attach.owner = current; 353 vhost_work_init(&attach.work, vhost_attach_cgroups_work); 354 vhost_work_queue(dev, &attach.work); 355 vhost_work_flush(dev, &attach.work); 356 return attach.ret; 357 } 358 359 /* Caller should have device mutex */ 360 bool vhost_dev_has_owner(struct vhost_dev *dev) 361 { 362 return dev->mm; 363 } 364 EXPORT_SYMBOL_GPL(vhost_dev_has_owner); 365 366 /* Caller should have device mutex */ 367 long vhost_dev_set_owner(struct vhost_dev *dev) 368 { 369 struct task_struct *worker; 370 int err; 371 372 /* Is there an owner already? */ 373 if (vhost_dev_has_owner(dev)) { 374 err = -EBUSY; 375 goto err_mm; 376 } 377 378 /* No owner, become one */ 379 dev->mm = get_task_mm(current); 380 worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid); 381 if (IS_ERR(worker)) { 382 err = PTR_ERR(worker); 383 goto err_worker; 384 } 385 386 dev->worker = worker; 387 wake_up_process(worker); /* avoid contributing to loadavg */ 388 389 err = vhost_attach_cgroups(dev); 390 if (err) 391 goto err_cgroup; 392 393 err = vhost_dev_alloc_iovecs(dev); 394 if (err) 395 goto err_cgroup; 396 397 return 0; 398 err_cgroup: 399 kthread_stop(worker); 400 dev->worker = NULL; 401 err_worker: 402 if (dev->mm) 403 mmput(dev->mm); 404 dev->mm = NULL; 405 err_mm: 406 return err; 407 } 408 EXPORT_SYMBOL_GPL(vhost_dev_set_owner); 409 410 struct vhost_memory *vhost_dev_reset_owner_prepare(void) 411 { 412 return kmalloc(offsetof(struct vhost_memory, regions), GFP_KERNEL); 413 } 414 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner_prepare); 415 416 /* Caller should have device mutex */ 417 void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_memory *memory) 418 { 419 int i; 420 421 vhost_dev_cleanup(dev, true); 422 423 /* Restore memory to default empty mapping. */ 424 memory->nregions = 0; 425 dev->memory = memory; 426 /* We don't need VQ locks below since vhost_dev_cleanup makes sure 427 * VQs aren't running. 428 */ 429 for (i = 0; i < dev->nvqs; ++i) 430 dev->vqs[i]->memory = memory; 431 } 432 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner); 433 434 void vhost_dev_stop(struct vhost_dev *dev) 435 { 436 int i; 437 438 for (i = 0; i < dev->nvqs; ++i) { 439 if (dev->vqs[i]->kick && dev->vqs[i]->handle_kick) { 440 vhost_poll_stop(&dev->vqs[i]->poll); 441 vhost_poll_flush(&dev->vqs[i]->poll); 442 } 443 } 444 } 445 EXPORT_SYMBOL_GPL(vhost_dev_stop); 446 447 /* Caller should have device mutex if and only if locked is set */ 448 void vhost_dev_cleanup(struct vhost_dev *dev, bool locked) 449 { 450 int i; 451 452 for (i = 0; i < dev->nvqs; ++i) { 453 if (dev->vqs[i]->error_ctx) 454 eventfd_ctx_put(dev->vqs[i]->error_ctx); 455 if (dev->vqs[i]->error) 456 fput(dev->vqs[i]->error); 457 if (dev->vqs[i]->kick) 458 fput(dev->vqs[i]->kick); 459 if (dev->vqs[i]->call_ctx) 460 eventfd_ctx_put(dev->vqs[i]->call_ctx); 461 if (dev->vqs[i]->call) 462 fput(dev->vqs[i]->call); 463 vhost_vq_reset(dev, dev->vqs[i]); 464 } 465 vhost_dev_free_iovecs(dev); 466 if (dev->log_ctx) 467 eventfd_ctx_put(dev->log_ctx); 468 dev->log_ctx = NULL; 469 if (dev->log_file) 470 fput(dev->log_file); 471 dev->log_file = NULL; 472 /* No one will access memory at this point */ 473 kfree(dev->memory); 474 dev->memory = NULL; 475 WARN_ON(!list_empty(&dev->work_list)); 476 if (dev->worker) { 477 kthread_stop(dev->worker); 478 dev->worker = NULL; 479 } 480 if (dev->mm) 481 mmput(dev->mm); 482 dev->mm = NULL; 483 } 484 EXPORT_SYMBOL_GPL(vhost_dev_cleanup); 485 486 static int log_access_ok(void __user *log_base, u64 addr, unsigned long sz) 487 { 488 u64 a = addr / VHOST_PAGE_SIZE / 8; 489 490 /* Make sure 64 bit math will not overflow. */ 491 if (a > ULONG_MAX - (unsigned long)log_base || 492 a + (unsigned long)log_base > ULONG_MAX) 493 return 0; 494 495 return access_ok(VERIFY_WRITE, log_base + a, 496 (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8); 497 } 498 499 /* Caller should have vq mutex and device mutex. */ 500 static int vq_memory_access_ok(void __user *log_base, struct vhost_memory *mem, 501 int log_all) 502 { 503 int i; 504 505 if (!mem) 506 return 0; 507 508 for (i = 0; i < mem->nregions; ++i) { 509 struct vhost_memory_region *m = mem->regions + i; 510 unsigned long a = m->userspace_addr; 511 if (m->memory_size > ULONG_MAX) 512 return 0; 513 else if (!access_ok(VERIFY_WRITE, (void __user *)a, 514 m->memory_size)) 515 return 0; 516 else if (log_all && !log_access_ok(log_base, 517 m->guest_phys_addr, 518 m->memory_size)) 519 return 0; 520 } 521 return 1; 522 } 523 524 /* Can we switch to this memory table? */ 525 /* Caller should have device mutex but not vq mutex */ 526 static int memory_access_ok(struct vhost_dev *d, struct vhost_memory *mem, 527 int log_all) 528 { 529 int i; 530 531 for (i = 0; i < d->nvqs; ++i) { 532 int ok; 533 bool log; 534 535 mutex_lock(&d->vqs[i]->mutex); 536 log = log_all || vhost_has_feature(d->vqs[i], VHOST_F_LOG_ALL); 537 /* If ring is inactive, will check when it's enabled. */ 538 if (d->vqs[i]->private_data) 539 ok = vq_memory_access_ok(d->vqs[i]->log_base, mem, log); 540 else 541 ok = 1; 542 mutex_unlock(&d->vqs[i]->mutex); 543 if (!ok) 544 return 0; 545 } 546 return 1; 547 } 548 549 static int vq_access_ok(struct vhost_virtqueue *vq, unsigned int num, 550 struct vring_desc __user *desc, 551 struct vring_avail __user *avail, 552 struct vring_used __user *used) 553 { 554 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0; 555 return access_ok(VERIFY_READ, desc, num * sizeof *desc) && 556 access_ok(VERIFY_READ, avail, 557 sizeof *avail + num * sizeof *avail->ring + s) && 558 access_ok(VERIFY_WRITE, used, 559 sizeof *used + num * sizeof *used->ring + s); 560 } 561 562 /* Can we log writes? */ 563 /* Caller should have device mutex but not vq mutex */ 564 int vhost_log_access_ok(struct vhost_dev *dev) 565 { 566 return memory_access_ok(dev, dev->memory, 1); 567 } 568 EXPORT_SYMBOL_GPL(vhost_log_access_ok); 569 570 /* Verify access for write logging. */ 571 /* Caller should have vq mutex and device mutex */ 572 static int vq_log_access_ok(struct vhost_virtqueue *vq, 573 void __user *log_base) 574 { 575 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0; 576 577 return vq_memory_access_ok(log_base, vq->memory, 578 vhost_has_feature(vq, VHOST_F_LOG_ALL)) && 579 (!vq->log_used || log_access_ok(log_base, vq->log_addr, 580 sizeof *vq->used + 581 vq->num * sizeof *vq->used->ring + s)); 582 } 583 584 /* Can we start vq? */ 585 /* Caller should have vq mutex and device mutex */ 586 int vhost_vq_access_ok(struct vhost_virtqueue *vq) 587 { 588 return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used) && 589 vq_log_access_ok(vq, vq->log_base); 590 } 591 EXPORT_SYMBOL_GPL(vhost_vq_access_ok); 592 593 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m) 594 { 595 struct vhost_memory mem, *newmem, *oldmem; 596 unsigned long size = offsetof(struct vhost_memory, regions); 597 int i; 598 599 if (copy_from_user(&mem, m, size)) 600 return -EFAULT; 601 if (mem.padding) 602 return -EOPNOTSUPP; 603 if (mem.nregions > VHOST_MEMORY_MAX_NREGIONS) 604 return -E2BIG; 605 newmem = kmalloc(size + mem.nregions * sizeof *m->regions, GFP_KERNEL); 606 if (!newmem) 607 return -ENOMEM; 608 609 memcpy(newmem, &mem, size); 610 if (copy_from_user(newmem->regions, m->regions, 611 mem.nregions * sizeof *m->regions)) { 612 kfree(newmem); 613 return -EFAULT; 614 } 615 616 if (!memory_access_ok(d, newmem, 0)) { 617 kfree(newmem); 618 return -EFAULT; 619 } 620 oldmem = d->memory; 621 d->memory = newmem; 622 623 /* All memory accesses are done under some VQ mutex. */ 624 for (i = 0; i < d->nvqs; ++i) { 625 mutex_lock(&d->vqs[i]->mutex); 626 d->vqs[i]->memory = newmem; 627 mutex_unlock(&d->vqs[i]->mutex); 628 } 629 kfree(oldmem); 630 return 0; 631 } 632 633 long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp) 634 { 635 struct file *eventfp, *filep = NULL; 636 bool pollstart = false, pollstop = false; 637 struct eventfd_ctx *ctx = NULL; 638 u32 __user *idxp = argp; 639 struct vhost_virtqueue *vq; 640 struct vhost_vring_state s; 641 struct vhost_vring_file f; 642 struct vhost_vring_addr a; 643 u32 idx; 644 long r; 645 646 r = get_user(idx, idxp); 647 if (r < 0) 648 return r; 649 if (idx >= d->nvqs) 650 return -ENOBUFS; 651 652 vq = d->vqs[idx]; 653 654 mutex_lock(&vq->mutex); 655 656 switch (ioctl) { 657 case VHOST_SET_VRING_NUM: 658 /* Resizing ring with an active backend? 659 * You don't want to do that. */ 660 if (vq->private_data) { 661 r = -EBUSY; 662 break; 663 } 664 if (copy_from_user(&s, argp, sizeof s)) { 665 r = -EFAULT; 666 break; 667 } 668 if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) { 669 r = -EINVAL; 670 break; 671 } 672 vq->num = s.num; 673 break; 674 case VHOST_SET_VRING_BASE: 675 /* Moving base with an active backend? 676 * You don't want to do that. */ 677 if (vq->private_data) { 678 r = -EBUSY; 679 break; 680 } 681 if (copy_from_user(&s, argp, sizeof s)) { 682 r = -EFAULT; 683 break; 684 } 685 if (s.num > 0xffff) { 686 r = -EINVAL; 687 break; 688 } 689 vq->last_avail_idx = s.num; 690 /* Forget the cached index value. */ 691 vq->avail_idx = vq->last_avail_idx; 692 break; 693 case VHOST_GET_VRING_BASE: 694 s.index = idx; 695 s.num = vq->last_avail_idx; 696 if (copy_to_user(argp, &s, sizeof s)) 697 r = -EFAULT; 698 break; 699 case VHOST_SET_VRING_ADDR: 700 if (copy_from_user(&a, argp, sizeof a)) { 701 r = -EFAULT; 702 break; 703 } 704 if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) { 705 r = -EOPNOTSUPP; 706 break; 707 } 708 /* For 32bit, verify that the top 32bits of the user 709 data are set to zero. */ 710 if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr || 711 (u64)(unsigned long)a.used_user_addr != a.used_user_addr || 712 (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) { 713 r = -EFAULT; 714 break; 715 } 716 717 /* Make sure it's safe to cast pointers to vring types. */ 718 BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE); 719 BUILD_BUG_ON(__alignof__ *vq->used > VRING_USED_ALIGN_SIZE); 720 if ((a.avail_user_addr & (VRING_AVAIL_ALIGN_SIZE - 1)) || 721 (a.used_user_addr & (VRING_USED_ALIGN_SIZE - 1)) || 722 (a.log_guest_addr & (sizeof(u64) - 1))) { 723 r = -EINVAL; 724 break; 725 } 726 727 /* We only verify access here if backend is configured. 728 * If it is not, we don't as size might not have been setup. 729 * We will verify when backend is configured. */ 730 if (vq->private_data) { 731 if (!vq_access_ok(vq, vq->num, 732 (void __user *)(unsigned long)a.desc_user_addr, 733 (void __user *)(unsigned long)a.avail_user_addr, 734 (void __user *)(unsigned long)a.used_user_addr)) { 735 r = -EINVAL; 736 break; 737 } 738 739 /* Also validate log access for used ring if enabled. */ 740 if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) && 741 !log_access_ok(vq->log_base, a.log_guest_addr, 742 sizeof *vq->used + 743 vq->num * sizeof *vq->used->ring)) { 744 r = -EINVAL; 745 break; 746 } 747 } 748 749 vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG)); 750 vq->desc = (void __user *)(unsigned long)a.desc_user_addr; 751 vq->avail = (void __user *)(unsigned long)a.avail_user_addr; 752 vq->log_addr = a.log_guest_addr; 753 vq->used = (void __user *)(unsigned long)a.used_user_addr; 754 break; 755 case VHOST_SET_VRING_KICK: 756 if (copy_from_user(&f, argp, sizeof f)) { 757 r = -EFAULT; 758 break; 759 } 760 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); 761 if (IS_ERR(eventfp)) { 762 r = PTR_ERR(eventfp); 763 break; 764 } 765 if (eventfp != vq->kick) { 766 pollstop = (filep = vq->kick) != NULL; 767 pollstart = (vq->kick = eventfp) != NULL; 768 } else 769 filep = eventfp; 770 break; 771 case VHOST_SET_VRING_CALL: 772 if (copy_from_user(&f, argp, sizeof f)) { 773 r = -EFAULT; 774 break; 775 } 776 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); 777 if (IS_ERR(eventfp)) { 778 r = PTR_ERR(eventfp); 779 break; 780 } 781 if (eventfp != vq->call) { 782 filep = vq->call; 783 ctx = vq->call_ctx; 784 vq->call = eventfp; 785 vq->call_ctx = eventfp ? 786 eventfd_ctx_fileget(eventfp) : NULL; 787 } else 788 filep = eventfp; 789 break; 790 case VHOST_SET_VRING_ERR: 791 if (copy_from_user(&f, argp, sizeof f)) { 792 r = -EFAULT; 793 break; 794 } 795 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); 796 if (IS_ERR(eventfp)) { 797 r = PTR_ERR(eventfp); 798 break; 799 } 800 if (eventfp != vq->error) { 801 filep = vq->error; 802 vq->error = eventfp; 803 ctx = vq->error_ctx; 804 vq->error_ctx = eventfp ? 805 eventfd_ctx_fileget(eventfp) : NULL; 806 } else 807 filep = eventfp; 808 break; 809 default: 810 r = -ENOIOCTLCMD; 811 } 812 813 if (pollstop && vq->handle_kick) 814 vhost_poll_stop(&vq->poll); 815 816 if (ctx) 817 eventfd_ctx_put(ctx); 818 if (filep) 819 fput(filep); 820 821 if (pollstart && vq->handle_kick) 822 r = vhost_poll_start(&vq->poll, vq->kick); 823 824 mutex_unlock(&vq->mutex); 825 826 if (pollstop && vq->handle_kick) 827 vhost_poll_flush(&vq->poll); 828 return r; 829 } 830 EXPORT_SYMBOL_GPL(vhost_vring_ioctl); 831 832 /* Caller must have device mutex */ 833 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp) 834 { 835 struct file *eventfp, *filep = NULL; 836 struct eventfd_ctx *ctx = NULL; 837 u64 p; 838 long r; 839 int i, fd; 840 841 /* If you are not the owner, you can become one */ 842 if (ioctl == VHOST_SET_OWNER) { 843 r = vhost_dev_set_owner(d); 844 goto done; 845 } 846 847 /* You must be the owner to do anything else */ 848 r = vhost_dev_check_owner(d); 849 if (r) 850 goto done; 851 852 switch (ioctl) { 853 case VHOST_SET_MEM_TABLE: 854 r = vhost_set_memory(d, argp); 855 break; 856 case VHOST_SET_LOG_BASE: 857 if (copy_from_user(&p, argp, sizeof p)) { 858 r = -EFAULT; 859 break; 860 } 861 if ((u64)(unsigned long)p != p) { 862 r = -EFAULT; 863 break; 864 } 865 for (i = 0; i < d->nvqs; ++i) { 866 struct vhost_virtqueue *vq; 867 void __user *base = (void __user *)(unsigned long)p; 868 vq = d->vqs[i]; 869 mutex_lock(&vq->mutex); 870 /* If ring is inactive, will check when it's enabled. */ 871 if (vq->private_data && !vq_log_access_ok(vq, base)) 872 r = -EFAULT; 873 else 874 vq->log_base = base; 875 mutex_unlock(&vq->mutex); 876 } 877 break; 878 case VHOST_SET_LOG_FD: 879 r = get_user(fd, (int __user *)argp); 880 if (r < 0) 881 break; 882 eventfp = fd == -1 ? NULL : eventfd_fget(fd); 883 if (IS_ERR(eventfp)) { 884 r = PTR_ERR(eventfp); 885 break; 886 } 887 if (eventfp != d->log_file) { 888 filep = d->log_file; 889 ctx = d->log_ctx; 890 d->log_ctx = eventfp ? 891 eventfd_ctx_fileget(eventfp) : NULL; 892 } else 893 filep = eventfp; 894 for (i = 0; i < d->nvqs; ++i) { 895 mutex_lock(&d->vqs[i]->mutex); 896 d->vqs[i]->log_ctx = d->log_ctx; 897 mutex_unlock(&d->vqs[i]->mutex); 898 } 899 if (ctx) 900 eventfd_ctx_put(ctx); 901 if (filep) 902 fput(filep); 903 break; 904 default: 905 r = -ENOIOCTLCMD; 906 break; 907 } 908 done: 909 return r; 910 } 911 EXPORT_SYMBOL_GPL(vhost_dev_ioctl); 912 913 static const struct vhost_memory_region *find_region(struct vhost_memory *mem, 914 __u64 addr, __u32 len) 915 { 916 struct vhost_memory_region *reg; 917 int i; 918 919 /* linear search is not brilliant, but we really have on the order of 6 920 * regions in practice */ 921 for (i = 0; i < mem->nregions; ++i) { 922 reg = mem->regions + i; 923 if (reg->guest_phys_addr <= addr && 924 reg->guest_phys_addr + reg->memory_size - 1 >= addr) 925 return reg; 926 } 927 return NULL; 928 } 929 930 /* TODO: This is really inefficient. We need something like get_user() 931 * (instruction directly accesses the data, with an exception table entry 932 * returning -EFAULT). See Documentation/x86/exception-tables.txt. 933 */ 934 static int set_bit_to_user(int nr, void __user *addr) 935 { 936 unsigned long log = (unsigned long)addr; 937 struct page *page; 938 void *base; 939 int bit = nr + (log % PAGE_SIZE) * 8; 940 int r; 941 942 r = get_user_pages_fast(log, 1, 1, &page); 943 if (r < 0) 944 return r; 945 BUG_ON(r != 1); 946 base = kmap_atomic(page); 947 set_bit(bit, base); 948 kunmap_atomic(base); 949 set_page_dirty_lock(page); 950 put_page(page); 951 return 0; 952 } 953 954 static int log_write(void __user *log_base, 955 u64 write_address, u64 write_length) 956 { 957 u64 write_page = write_address / VHOST_PAGE_SIZE; 958 int r; 959 960 if (!write_length) 961 return 0; 962 write_length += write_address % VHOST_PAGE_SIZE; 963 for (;;) { 964 u64 base = (u64)(unsigned long)log_base; 965 u64 log = base + write_page / 8; 966 int bit = write_page % 8; 967 if ((u64)(unsigned long)log != log) 968 return -EFAULT; 969 r = set_bit_to_user(bit, (void __user *)(unsigned long)log); 970 if (r < 0) 971 return r; 972 if (write_length <= VHOST_PAGE_SIZE) 973 break; 974 write_length -= VHOST_PAGE_SIZE; 975 write_page += 1; 976 } 977 return r; 978 } 979 980 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log, 981 unsigned int log_num, u64 len) 982 { 983 int i, r; 984 985 /* Make sure data written is seen before log. */ 986 smp_wmb(); 987 for (i = 0; i < log_num; ++i) { 988 u64 l = min(log[i].len, len); 989 r = log_write(vq->log_base, log[i].addr, l); 990 if (r < 0) 991 return r; 992 len -= l; 993 if (!len) { 994 if (vq->log_ctx) 995 eventfd_signal(vq->log_ctx, 1); 996 return 0; 997 } 998 } 999 /* Length written exceeds what we have stored. This is a bug. */ 1000 BUG(); 1001 return 0; 1002 } 1003 EXPORT_SYMBOL_GPL(vhost_log_write); 1004 1005 static int vhost_update_used_flags(struct vhost_virtqueue *vq) 1006 { 1007 void __user *used; 1008 if (__put_user(cpu_to_vhost16(vq, vq->used_flags), &vq->used->flags) < 0) 1009 return -EFAULT; 1010 if (unlikely(vq->log_used)) { 1011 /* Make sure the flag is seen before log. */ 1012 smp_wmb(); 1013 /* Log used flag write. */ 1014 used = &vq->used->flags; 1015 log_write(vq->log_base, vq->log_addr + 1016 (used - (void __user *)vq->used), 1017 sizeof vq->used->flags); 1018 if (vq->log_ctx) 1019 eventfd_signal(vq->log_ctx, 1); 1020 } 1021 return 0; 1022 } 1023 1024 static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event) 1025 { 1026 if (__put_user(cpu_to_vhost16(vq, vq->avail_idx), vhost_avail_event(vq))) 1027 return -EFAULT; 1028 if (unlikely(vq->log_used)) { 1029 void __user *used; 1030 /* Make sure the event is seen before log. */ 1031 smp_wmb(); 1032 /* Log avail event write */ 1033 used = vhost_avail_event(vq); 1034 log_write(vq->log_base, vq->log_addr + 1035 (used - (void __user *)vq->used), 1036 sizeof *vhost_avail_event(vq)); 1037 if (vq->log_ctx) 1038 eventfd_signal(vq->log_ctx, 1); 1039 } 1040 return 0; 1041 } 1042 1043 int vhost_init_used(struct vhost_virtqueue *vq) 1044 { 1045 __virtio16 last_used_idx; 1046 int r; 1047 if (!vq->private_data) 1048 return 0; 1049 1050 r = vhost_update_used_flags(vq); 1051 if (r) 1052 return r; 1053 vq->signalled_used_valid = false; 1054 if (!access_ok(VERIFY_READ, &vq->used->idx, sizeof vq->used->idx)) 1055 return -EFAULT; 1056 r = __get_user(last_used_idx, &vq->used->idx); 1057 if (r) 1058 return r; 1059 vq->last_used_idx = vhost16_to_cpu(vq, last_used_idx); 1060 return 0; 1061 } 1062 EXPORT_SYMBOL_GPL(vhost_init_used); 1063 1064 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len, 1065 struct iovec iov[], int iov_size) 1066 { 1067 const struct vhost_memory_region *reg; 1068 struct vhost_memory *mem; 1069 struct iovec *_iov; 1070 u64 s = 0; 1071 int ret = 0; 1072 1073 mem = vq->memory; 1074 while ((u64)len > s) { 1075 u64 size; 1076 if (unlikely(ret >= iov_size)) { 1077 ret = -ENOBUFS; 1078 break; 1079 } 1080 reg = find_region(mem, addr, len); 1081 if (unlikely(!reg)) { 1082 ret = -EFAULT; 1083 break; 1084 } 1085 _iov = iov + ret; 1086 size = reg->memory_size - addr + reg->guest_phys_addr; 1087 _iov->iov_len = min((u64)len - s, size); 1088 _iov->iov_base = (void __user *)(unsigned long) 1089 (reg->userspace_addr + addr - reg->guest_phys_addr); 1090 s += size; 1091 addr += size; 1092 ++ret; 1093 } 1094 1095 return ret; 1096 } 1097 1098 /* Each buffer in the virtqueues is actually a chain of descriptors. This 1099 * function returns the next descriptor in the chain, 1100 * or -1U if we're at the end. */ 1101 static unsigned next_desc(struct vhost_virtqueue *vq, struct vring_desc *desc) 1102 { 1103 unsigned int next; 1104 1105 /* If this descriptor says it doesn't chain, we're done. */ 1106 if (!(desc->flags & cpu_to_vhost16(vq, VRING_DESC_F_NEXT))) 1107 return -1U; 1108 1109 /* Check they're not leading us off end of descriptors. */ 1110 next = vhost16_to_cpu(vq, desc->next); 1111 /* Make sure compiler knows to grab that: we don't want it changing! */ 1112 /* We will use the result as an index in an array, so most 1113 * architectures only need a compiler barrier here. */ 1114 read_barrier_depends(); 1115 1116 return next; 1117 } 1118 1119 static int get_indirect(struct vhost_virtqueue *vq, 1120 struct iovec iov[], unsigned int iov_size, 1121 unsigned int *out_num, unsigned int *in_num, 1122 struct vhost_log *log, unsigned int *log_num, 1123 struct vring_desc *indirect) 1124 { 1125 struct vring_desc desc; 1126 unsigned int i = 0, count, found = 0; 1127 u32 len = vhost32_to_cpu(vq, indirect->len); 1128 struct iov_iter from; 1129 int ret; 1130 1131 /* Sanity check */ 1132 if (unlikely(len % sizeof desc)) { 1133 vq_err(vq, "Invalid length in indirect descriptor: " 1134 "len 0x%llx not multiple of 0x%zx\n", 1135 (unsigned long long)len, 1136 sizeof desc); 1137 return -EINVAL; 1138 } 1139 1140 ret = translate_desc(vq, vhost64_to_cpu(vq, indirect->addr), len, vq->indirect, 1141 UIO_MAXIOV); 1142 if (unlikely(ret < 0)) { 1143 vq_err(vq, "Translation failure %d in indirect.\n", ret); 1144 return ret; 1145 } 1146 iov_iter_init(&from, READ, vq->indirect, ret, len); 1147 1148 /* We will use the result as an address to read from, so most 1149 * architectures only need a compiler barrier here. */ 1150 read_barrier_depends(); 1151 1152 count = len / sizeof desc; 1153 /* Buffers are chained via a 16 bit next field, so 1154 * we can have at most 2^16 of these. */ 1155 if (unlikely(count > USHRT_MAX + 1)) { 1156 vq_err(vq, "Indirect buffer length too big: %d\n", 1157 indirect->len); 1158 return -E2BIG; 1159 } 1160 1161 do { 1162 unsigned iov_count = *in_num + *out_num; 1163 if (unlikely(++found > count)) { 1164 vq_err(vq, "Loop detected: last one at %u " 1165 "indirect size %u\n", 1166 i, count); 1167 return -EINVAL; 1168 } 1169 if (unlikely(copy_from_iter(&desc, sizeof(desc), &from) != 1170 sizeof(desc))) { 1171 vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n", 1172 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc); 1173 return -EINVAL; 1174 } 1175 if (unlikely(desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT))) { 1176 vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n", 1177 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc); 1178 return -EINVAL; 1179 } 1180 1181 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr), 1182 vhost32_to_cpu(vq, desc.len), iov + iov_count, 1183 iov_size - iov_count); 1184 if (unlikely(ret < 0)) { 1185 vq_err(vq, "Translation failure %d indirect idx %d\n", 1186 ret, i); 1187 return ret; 1188 } 1189 /* If this is an input descriptor, increment that count. */ 1190 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE)) { 1191 *in_num += ret; 1192 if (unlikely(log)) { 1193 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr); 1194 log[*log_num].len = vhost32_to_cpu(vq, desc.len); 1195 ++*log_num; 1196 } 1197 } else { 1198 /* If it's an output descriptor, they're all supposed 1199 * to come before any input descriptors. */ 1200 if (unlikely(*in_num)) { 1201 vq_err(vq, "Indirect descriptor " 1202 "has out after in: idx %d\n", i); 1203 return -EINVAL; 1204 } 1205 *out_num += ret; 1206 } 1207 } while ((i = next_desc(vq, &desc)) != -1); 1208 return 0; 1209 } 1210 1211 /* This looks in the virtqueue and for the first available buffer, and converts 1212 * it to an iovec for convenient access. Since descriptors consist of some 1213 * number of output then some number of input descriptors, it's actually two 1214 * iovecs, but we pack them into one and note how many of each there were. 1215 * 1216 * This function returns the descriptor number found, or vq->num (which is 1217 * never a valid descriptor number) if none was found. A negative code is 1218 * returned on error. */ 1219 int vhost_get_vq_desc(struct vhost_virtqueue *vq, 1220 struct iovec iov[], unsigned int iov_size, 1221 unsigned int *out_num, unsigned int *in_num, 1222 struct vhost_log *log, unsigned int *log_num) 1223 { 1224 struct vring_desc desc; 1225 unsigned int i, head, found = 0; 1226 u16 last_avail_idx; 1227 __virtio16 avail_idx; 1228 __virtio16 ring_head; 1229 int ret; 1230 1231 /* Check it isn't doing very strange things with descriptor numbers. */ 1232 last_avail_idx = vq->last_avail_idx; 1233 if (unlikely(__get_user(avail_idx, &vq->avail->idx))) { 1234 vq_err(vq, "Failed to access avail idx at %p\n", 1235 &vq->avail->idx); 1236 return -EFAULT; 1237 } 1238 vq->avail_idx = vhost16_to_cpu(vq, avail_idx); 1239 1240 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) { 1241 vq_err(vq, "Guest moved used index from %u to %u", 1242 last_avail_idx, vq->avail_idx); 1243 return -EFAULT; 1244 } 1245 1246 /* If there's nothing new since last we looked, return invalid. */ 1247 if (vq->avail_idx == last_avail_idx) 1248 return vq->num; 1249 1250 /* Only get avail ring entries after they have been exposed by guest. */ 1251 smp_rmb(); 1252 1253 /* Grab the next descriptor number they're advertising, and increment 1254 * the index we've seen. */ 1255 if (unlikely(__get_user(ring_head, 1256 &vq->avail->ring[last_avail_idx % vq->num]))) { 1257 vq_err(vq, "Failed to read head: idx %d address %p\n", 1258 last_avail_idx, 1259 &vq->avail->ring[last_avail_idx % vq->num]); 1260 return -EFAULT; 1261 } 1262 1263 head = vhost16_to_cpu(vq, ring_head); 1264 1265 /* If their number is silly, that's an error. */ 1266 if (unlikely(head >= vq->num)) { 1267 vq_err(vq, "Guest says index %u > %u is available", 1268 head, vq->num); 1269 return -EINVAL; 1270 } 1271 1272 /* When we start there are none of either input nor output. */ 1273 *out_num = *in_num = 0; 1274 if (unlikely(log)) 1275 *log_num = 0; 1276 1277 i = head; 1278 do { 1279 unsigned iov_count = *in_num + *out_num; 1280 if (unlikely(i >= vq->num)) { 1281 vq_err(vq, "Desc index is %u > %u, head = %u", 1282 i, vq->num, head); 1283 return -EINVAL; 1284 } 1285 if (unlikely(++found > vq->num)) { 1286 vq_err(vq, "Loop detected: last one at %u " 1287 "vq size %u head %u\n", 1288 i, vq->num, head); 1289 return -EINVAL; 1290 } 1291 ret = __copy_from_user(&desc, vq->desc + i, sizeof desc); 1292 if (unlikely(ret)) { 1293 vq_err(vq, "Failed to get descriptor: idx %d addr %p\n", 1294 i, vq->desc + i); 1295 return -EFAULT; 1296 } 1297 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT)) { 1298 ret = get_indirect(vq, iov, iov_size, 1299 out_num, in_num, 1300 log, log_num, &desc); 1301 if (unlikely(ret < 0)) { 1302 vq_err(vq, "Failure detected " 1303 "in indirect descriptor at idx %d\n", i); 1304 return ret; 1305 } 1306 continue; 1307 } 1308 1309 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr), 1310 vhost32_to_cpu(vq, desc.len), iov + iov_count, 1311 iov_size - iov_count); 1312 if (unlikely(ret < 0)) { 1313 vq_err(vq, "Translation failure %d descriptor idx %d\n", 1314 ret, i); 1315 return ret; 1316 } 1317 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE)) { 1318 /* If this is an input descriptor, 1319 * increment that count. */ 1320 *in_num += ret; 1321 if (unlikely(log)) { 1322 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr); 1323 log[*log_num].len = vhost32_to_cpu(vq, desc.len); 1324 ++*log_num; 1325 } 1326 } else { 1327 /* If it's an output descriptor, they're all supposed 1328 * to come before any input descriptors. */ 1329 if (unlikely(*in_num)) { 1330 vq_err(vq, "Descriptor has out after in: " 1331 "idx %d\n", i); 1332 return -EINVAL; 1333 } 1334 *out_num += ret; 1335 } 1336 } while ((i = next_desc(vq, &desc)) != -1); 1337 1338 /* On success, increment avail index. */ 1339 vq->last_avail_idx++; 1340 1341 /* Assume notifications from guest are disabled at this point, 1342 * if they aren't we would need to update avail_event index. */ 1343 BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY)); 1344 return head; 1345 } 1346 EXPORT_SYMBOL_GPL(vhost_get_vq_desc); 1347 1348 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */ 1349 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n) 1350 { 1351 vq->last_avail_idx -= n; 1352 } 1353 EXPORT_SYMBOL_GPL(vhost_discard_vq_desc); 1354 1355 /* After we've used one of their buffers, we tell them about it. We'll then 1356 * want to notify the guest, using eventfd. */ 1357 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len) 1358 { 1359 struct vring_used_elem heads = { 1360 cpu_to_vhost32(vq, head), 1361 cpu_to_vhost32(vq, len) 1362 }; 1363 1364 return vhost_add_used_n(vq, &heads, 1); 1365 } 1366 EXPORT_SYMBOL_GPL(vhost_add_used); 1367 1368 static int __vhost_add_used_n(struct vhost_virtqueue *vq, 1369 struct vring_used_elem *heads, 1370 unsigned count) 1371 { 1372 struct vring_used_elem __user *used; 1373 u16 old, new; 1374 int start; 1375 1376 start = vq->last_used_idx % vq->num; 1377 used = vq->used->ring + start; 1378 if (count == 1) { 1379 if (__put_user(heads[0].id, &used->id)) { 1380 vq_err(vq, "Failed to write used id"); 1381 return -EFAULT; 1382 } 1383 if (__put_user(heads[0].len, &used->len)) { 1384 vq_err(vq, "Failed to write used len"); 1385 return -EFAULT; 1386 } 1387 } else if (__copy_to_user(used, heads, count * sizeof *used)) { 1388 vq_err(vq, "Failed to write used"); 1389 return -EFAULT; 1390 } 1391 if (unlikely(vq->log_used)) { 1392 /* Make sure data is seen before log. */ 1393 smp_wmb(); 1394 /* Log used ring entry write. */ 1395 log_write(vq->log_base, 1396 vq->log_addr + 1397 ((void __user *)used - (void __user *)vq->used), 1398 count * sizeof *used); 1399 } 1400 old = vq->last_used_idx; 1401 new = (vq->last_used_idx += count); 1402 /* If the driver never bothers to signal in a very long while, 1403 * used index might wrap around. If that happens, invalidate 1404 * signalled_used index we stored. TODO: make sure driver 1405 * signals at least once in 2^16 and remove this. */ 1406 if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old))) 1407 vq->signalled_used_valid = false; 1408 return 0; 1409 } 1410 1411 /* After we've used one of their buffers, we tell them about it. We'll then 1412 * want to notify the guest, using eventfd. */ 1413 int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads, 1414 unsigned count) 1415 { 1416 int start, n, r; 1417 1418 start = vq->last_used_idx % vq->num; 1419 n = vq->num - start; 1420 if (n < count) { 1421 r = __vhost_add_used_n(vq, heads, n); 1422 if (r < 0) 1423 return r; 1424 heads += n; 1425 count -= n; 1426 } 1427 r = __vhost_add_used_n(vq, heads, count); 1428 1429 /* Make sure buffer is written before we update index. */ 1430 smp_wmb(); 1431 if (__put_user(cpu_to_vhost16(vq, vq->last_used_idx), &vq->used->idx)) { 1432 vq_err(vq, "Failed to increment used idx"); 1433 return -EFAULT; 1434 } 1435 if (unlikely(vq->log_used)) { 1436 /* Log used index update. */ 1437 log_write(vq->log_base, 1438 vq->log_addr + offsetof(struct vring_used, idx), 1439 sizeof vq->used->idx); 1440 if (vq->log_ctx) 1441 eventfd_signal(vq->log_ctx, 1); 1442 } 1443 return r; 1444 } 1445 EXPORT_SYMBOL_GPL(vhost_add_used_n); 1446 1447 static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) 1448 { 1449 __u16 old, new; 1450 __virtio16 event; 1451 bool v; 1452 /* Flush out used index updates. This is paired 1453 * with the barrier that the Guest executes when enabling 1454 * interrupts. */ 1455 smp_mb(); 1456 1457 if (vhost_has_feature(vq, VIRTIO_F_NOTIFY_ON_EMPTY) && 1458 unlikely(vq->avail_idx == vq->last_avail_idx)) 1459 return true; 1460 1461 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) { 1462 __virtio16 flags; 1463 if (__get_user(flags, &vq->avail->flags)) { 1464 vq_err(vq, "Failed to get flags"); 1465 return true; 1466 } 1467 return !(flags & cpu_to_vhost16(vq, VRING_AVAIL_F_NO_INTERRUPT)); 1468 } 1469 old = vq->signalled_used; 1470 v = vq->signalled_used_valid; 1471 new = vq->signalled_used = vq->last_used_idx; 1472 vq->signalled_used_valid = true; 1473 1474 if (unlikely(!v)) 1475 return true; 1476 1477 if (__get_user(event, vhost_used_event(vq))) { 1478 vq_err(vq, "Failed to get used event idx"); 1479 return true; 1480 } 1481 return vring_need_event(vhost16_to_cpu(vq, event), new, old); 1482 } 1483 1484 /* This actually signals the guest, using eventfd. */ 1485 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq) 1486 { 1487 /* Signal the Guest tell them we used something up. */ 1488 if (vq->call_ctx && vhost_notify(dev, vq)) 1489 eventfd_signal(vq->call_ctx, 1); 1490 } 1491 EXPORT_SYMBOL_GPL(vhost_signal); 1492 1493 /* And here's the combo meal deal. Supersize me! */ 1494 void vhost_add_used_and_signal(struct vhost_dev *dev, 1495 struct vhost_virtqueue *vq, 1496 unsigned int head, int len) 1497 { 1498 vhost_add_used(vq, head, len); 1499 vhost_signal(dev, vq); 1500 } 1501 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal); 1502 1503 /* multi-buffer version of vhost_add_used_and_signal */ 1504 void vhost_add_used_and_signal_n(struct vhost_dev *dev, 1505 struct vhost_virtqueue *vq, 1506 struct vring_used_elem *heads, unsigned count) 1507 { 1508 vhost_add_used_n(vq, heads, count); 1509 vhost_signal(dev, vq); 1510 } 1511 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n); 1512 1513 /* OK, now we need to know about added descriptors. */ 1514 bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) 1515 { 1516 __virtio16 avail_idx; 1517 int r; 1518 1519 if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY)) 1520 return false; 1521 vq->used_flags &= ~VRING_USED_F_NO_NOTIFY; 1522 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) { 1523 r = vhost_update_used_flags(vq); 1524 if (r) { 1525 vq_err(vq, "Failed to enable notification at %p: %d\n", 1526 &vq->used->flags, r); 1527 return false; 1528 } 1529 } else { 1530 r = vhost_update_avail_event(vq, vq->avail_idx); 1531 if (r) { 1532 vq_err(vq, "Failed to update avail event index at %p: %d\n", 1533 vhost_avail_event(vq), r); 1534 return false; 1535 } 1536 } 1537 /* They could have slipped one in as we were doing that: make 1538 * sure it's written, then check again. */ 1539 smp_mb(); 1540 r = __get_user(avail_idx, &vq->avail->idx); 1541 if (r) { 1542 vq_err(vq, "Failed to check avail idx at %p: %d\n", 1543 &vq->avail->idx, r); 1544 return false; 1545 } 1546 1547 return vhost16_to_cpu(vq, avail_idx) != vq->avail_idx; 1548 } 1549 EXPORT_SYMBOL_GPL(vhost_enable_notify); 1550 1551 /* We don't need to be notified again. */ 1552 void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) 1553 { 1554 int r; 1555 1556 if (vq->used_flags & VRING_USED_F_NO_NOTIFY) 1557 return; 1558 vq->used_flags |= VRING_USED_F_NO_NOTIFY; 1559 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) { 1560 r = vhost_update_used_flags(vq); 1561 if (r) 1562 vq_err(vq, "Failed to enable notification at %p: %d\n", 1563 &vq->used->flags, r); 1564 } 1565 } 1566 EXPORT_SYMBOL_GPL(vhost_disable_notify); 1567 1568 static int __init vhost_init(void) 1569 { 1570 return 0; 1571 } 1572 1573 static void __exit vhost_exit(void) 1574 { 1575 } 1576 1577 module_init(vhost_init); 1578 module_exit(vhost_exit); 1579 1580 MODULE_VERSION("0.0.1"); 1581 MODULE_LICENSE("GPL v2"); 1582 MODULE_AUTHOR("Michael S. Tsirkin"); 1583 MODULE_DESCRIPTION("Host kernel accelerator for virtio"); 1584