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 31enum { 32 VHOST_MEMORY_MAX_NREGIONS = 64, 33 VHOST_MEMORY_F_LOG = 0x1, 34}; 35 36#define vhost_used_event(vq) ((u16 __user *)&vq->avail->ring[vq->num]) 37#define vhost_avail_event(vq) ((u16 __user *)&vq->used->ring[vq->num]) 38 39static 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 49static 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 61void 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} 69EXPORT_SYMBOL_GPL(vhost_work_init); 70 71/* Init poll structure */ 72void 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} 83EXPORT_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. */ 87int 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} 106EXPORT_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. */ 110void 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} 117EXPORT_SYMBOL_GPL(vhost_poll_stop); 118 119static 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 130void 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} 145EXPORT_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. */ 149void vhost_poll_flush(struct vhost_poll *poll) 150{ 151 vhost_work_flush(poll->dev, &poll->work); 152} 153EXPORT_SYMBOL_GPL(vhost_poll_flush); 154 155void 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} 169EXPORT_SYMBOL_GPL(vhost_work_queue); 170 171void vhost_poll_queue(struct vhost_poll *poll) 172{ 173 vhost_work_queue(poll->dev, &poll->work); 174} 175EXPORT_SYMBOL_GPL(vhost_poll_queue); 176 177static 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 204static 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 253static 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. */ 264static 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 280err_nomem: 281 for (; i >= 0; --i) 282 vhost_vq_free_iovecs(dev->vqs[i]); 283 return -ENOMEM; 284} 285 286static 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 294void 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} 324EXPORT_SYMBOL_GPL(vhost_dev_init); 325 326/* Caller should have device mutex */ 327long 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} 332EXPORT_SYMBOL_GPL(vhost_dev_check_owner); 333 334struct vhost_attach_cgroups_struct { 335 struct vhost_work work; 336 struct task_struct *owner; 337 int ret; 338}; 339 340static 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 348static 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 */ 360bool vhost_dev_has_owner(struct vhost_dev *dev) 361{ 362 return dev->mm; 363} 364EXPORT_SYMBOL_GPL(vhost_dev_has_owner); 365 366/* Caller should have device mutex */ 367long 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; 398err_cgroup: 399 kthread_stop(worker); 400 dev->worker = NULL; 401err_worker: 402 if (dev->mm) 403 mmput(dev->mm); 404 dev->mm = NULL; 405err_mm: 406 return err; 407} 408EXPORT_SYMBOL_GPL(vhost_dev_set_owner); 409 410struct vhost_memory *vhost_dev_reset_owner_prepare(void) 411{ 412 return kmalloc(offsetof(struct vhost_memory, regions), GFP_KERNEL); 413} 414EXPORT_SYMBOL_GPL(vhost_dev_reset_owner_prepare); 415 416/* Caller should have device mutex */ 417void 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} 432EXPORT_SYMBOL_GPL(vhost_dev_reset_owner); 433 434void 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} 445EXPORT_SYMBOL_GPL(vhost_dev_stop); 446 447/* Caller should have device mutex if and only if locked is set */ 448void 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} 484EXPORT_SYMBOL_GPL(vhost_dev_cleanup); 485 486static 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. */ 500static 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 */ 526static 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 549static 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 */ 564int vhost_log_access_ok(struct vhost_dev *dev) 565{ 566 return memory_access_ok(dev, dev->memory, 1); 567} 568EXPORT_SYMBOL_GPL(vhost_log_access_ok); 569 570/* Verify access for write logging. */ 571/* Caller should have vq mutex and device mutex */ 572static 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 */ 586int 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} 591EXPORT_SYMBOL_GPL(vhost_vq_access_ok); 592 593static 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 633long 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 if ((a.avail_user_addr & (sizeof *vq->avail->ring - 1)) || 717 (a.used_user_addr & (sizeof *vq->used->ring - 1)) || 718 (a.log_guest_addr & (sizeof *vq->used->ring - 1))) { 719 r = -EINVAL; 720 break; 721 } 722 723 /* We only verify access here if backend is configured. 724 * If it is not, we don't as size might not have been setup. 725 * We will verify when backend is configured. */ 726 if (vq->private_data) { 727 if (!vq_access_ok(vq, vq->num, 728 (void __user *)(unsigned long)a.desc_user_addr, 729 (void __user *)(unsigned long)a.avail_user_addr, 730 (void __user *)(unsigned long)a.used_user_addr)) { 731 r = -EINVAL; 732 break; 733 } 734 735 /* Also validate log access for used ring if enabled. */ 736 if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) && 737 !log_access_ok(vq->log_base, a.log_guest_addr, 738 sizeof *vq->used + 739 vq->num * sizeof *vq->used->ring)) { 740 r = -EINVAL; 741 break; 742 } 743 } 744 745 vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG)); 746 vq->desc = (void __user *)(unsigned long)a.desc_user_addr; 747 vq->avail = (void __user *)(unsigned long)a.avail_user_addr; 748 vq->log_addr = a.log_guest_addr; 749 vq->used = (void __user *)(unsigned long)a.used_user_addr; 750 break; 751 case VHOST_SET_VRING_KICK: 752 if (copy_from_user(&f, argp, sizeof f)) { 753 r = -EFAULT; 754 break; 755 } 756 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); 757 if (IS_ERR(eventfp)) { 758 r = PTR_ERR(eventfp); 759 break; 760 } 761 if (eventfp != vq->kick) { 762 pollstop = (filep = vq->kick) != NULL; 763 pollstart = (vq->kick = eventfp) != NULL; 764 } else 765 filep = eventfp; 766 break; 767 case VHOST_SET_VRING_CALL: 768 if (copy_from_user(&f, argp, sizeof f)) { 769 r = -EFAULT; 770 break; 771 } 772 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); 773 if (IS_ERR(eventfp)) { 774 r = PTR_ERR(eventfp); 775 break; 776 } 777 if (eventfp != vq->call) { 778 filep = vq->call; 779 ctx = vq->call_ctx; 780 vq->call = eventfp; 781 vq->call_ctx = eventfp ? 782 eventfd_ctx_fileget(eventfp) : NULL; 783 } else 784 filep = eventfp; 785 break; 786 case VHOST_SET_VRING_ERR: 787 if (copy_from_user(&f, argp, sizeof f)) { 788 r = -EFAULT; 789 break; 790 } 791 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); 792 if (IS_ERR(eventfp)) { 793 r = PTR_ERR(eventfp); 794 break; 795 } 796 if (eventfp != vq->error) { 797 filep = vq->error; 798 vq->error = eventfp; 799 ctx = vq->error_ctx; 800 vq->error_ctx = eventfp ? 801 eventfd_ctx_fileget(eventfp) : NULL; 802 } else 803 filep = eventfp; 804 break; 805 default: 806 r = -ENOIOCTLCMD; 807 } 808 809 if (pollstop && vq->handle_kick) 810 vhost_poll_stop(&vq->poll); 811 812 if (ctx) 813 eventfd_ctx_put(ctx); 814 if (filep) 815 fput(filep); 816 817 if (pollstart && vq->handle_kick) 818 r = vhost_poll_start(&vq->poll, vq->kick); 819 820 mutex_unlock(&vq->mutex); 821 822 if (pollstop && vq->handle_kick) 823 vhost_poll_flush(&vq->poll); 824 return r; 825} 826EXPORT_SYMBOL_GPL(vhost_vring_ioctl); 827 828/* Caller must have device mutex */ 829long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp) 830{ 831 struct file *eventfp, *filep = NULL; 832 struct eventfd_ctx *ctx = NULL; 833 u64 p; 834 long r; 835 int i, fd; 836 837 /* If you are not the owner, you can become one */ 838 if (ioctl == VHOST_SET_OWNER) { 839 r = vhost_dev_set_owner(d); 840 goto done; 841 } 842 843 /* You must be the owner to do anything else */ 844 r = vhost_dev_check_owner(d); 845 if (r) 846 goto done; 847 848 switch (ioctl) { 849 case VHOST_SET_MEM_TABLE: 850 r = vhost_set_memory(d, argp); 851 break; 852 case VHOST_SET_LOG_BASE: 853 if (copy_from_user(&p, argp, sizeof p)) { 854 r = -EFAULT; 855 break; 856 } 857 if ((u64)(unsigned long)p != p) { 858 r = -EFAULT; 859 break; 860 } 861 for (i = 0; i < d->nvqs; ++i) { 862 struct vhost_virtqueue *vq; 863 void __user *base = (void __user *)(unsigned long)p; 864 vq = d->vqs[i]; 865 mutex_lock(&vq->mutex); 866 /* If ring is inactive, will check when it's enabled. */ 867 if (vq->private_data && !vq_log_access_ok(vq, base)) 868 r = -EFAULT; 869 else 870 vq->log_base = base; 871 mutex_unlock(&vq->mutex); 872 } 873 break; 874 case VHOST_SET_LOG_FD: 875 r = get_user(fd, (int __user *)argp); 876 if (r < 0) 877 break; 878 eventfp = fd == -1 ? NULL : eventfd_fget(fd); 879 if (IS_ERR(eventfp)) { 880 r = PTR_ERR(eventfp); 881 break; 882 } 883 if (eventfp != d->log_file) { 884 filep = d->log_file; 885 ctx = d->log_ctx; 886 d->log_ctx = eventfp ? 887 eventfd_ctx_fileget(eventfp) : NULL; 888 } else 889 filep = eventfp; 890 for (i = 0; i < d->nvqs; ++i) { 891 mutex_lock(&d->vqs[i]->mutex); 892 d->vqs[i]->log_ctx = d->log_ctx; 893 mutex_unlock(&d->vqs[i]->mutex); 894 } 895 if (ctx) 896 eventfd_ctx_put(ctx); 897 if (filep) 898 fput(filep); 899 break; 900 default: 901 r = -ENOIOCTLCMD; 902 break; 903 } 904done: 905 return r; 906} 907EXPORT_SYMBOL_GPL(vhost_dev_ioctl); 908 909static const struct vhost_memory_region *find_region(struct vhost_memory *mem, 910 __u64 addr, __u32 len) 911{ 912 struct vhost_memory_region *reg; 913 int i; 914 915 /* linear search is not brilliant, but we really have on the order of 6 916 * regions in practice */ 917 for (i = 0; i < mem->nregions; ++i) { 918 reg = mem->regions + i; 919 if (reg->guest_phys_addr <= addr && 920 reg->guest_phys_addr + reg->memory_size - 1 >= addr) 921 return reg; 922 } 923 return NULL; 924} 925 926/* TODO: This is really inefficient. We need something like get_user() 927 * (instruction directly accesses the data, with an exception table entry 928 * returning -EFAULT). See Documentation/x86/exception-tables.txt. 929 */ 930static int set_bit_to_user(int nr, void __user *addr) 931{ 932 unsigned long log = (unsigned long)addr; 933 struct page *page; 934 void *base; 935 int bit = nr + (log % PAGE_SIZE) * 8; 936 int r; 937 938 r = get_user_pages_fast(log, 1, 1, &page); 939 if (r < 0) 940 return r; 941 BUG_ON(r != 1); 942 base = kmap_atomic(page); 943 set_bit(bit, base); 944 kunmap_atomic(base); 945 set_page_dirty_lock(page); 946 put_page(page); 947 return 0; 948} 949 950static int log_write(void __user *log_base, 951 u64 write_address, u64 write_length) 952{ 953 u64 write_page = write_address / VHOST_PAGE_SIZE; 954 int r; 955 956 if (!write_length) 957 return 0; 958 write_length += write_address % VHOST_PAGE_SIZE; 959 for (;;) { 960 u64 base = (u64)(unsigned long)log_base; 961 u64 log = base + write_page / 8; 962 int bit = write_page % 8; 963 if ((u64)(unsigned long)log != log) 964 return -EFAULT; 965 r = set_bit_to_user(bit, (void __user *)(unsigned long)log); 966 if (r < 0) 967 return r; 968 if (write_length <= VHOST_PAGE_SIZE) 969 break; 970 write_length -= VHOST_PAGE_SIZE; 971 write_page += 1; 972 } 973 return r; 974} 975 976int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log, 977 unsigned int log_num, u64 len) 978{ 979 int i, r; 980 981 /* Make sure data written is seen before log. */ 982 smp_wmb(); 983 for (i = 0; i < log_num; ++i) { 984 u64 l = min(log[i].len, len); 985 r = log_write(vq->log_base, log[i].addr, l); 986 if (r < 0) 987 return r; 988 len -= l; 989 if (!len) { 990 if (vq->log_ctx) 991 eventfd_signal(vq->log_ctx, 1); 992 return 0; 993 } 994 } 995 /* Length written exceeds what we have stored. This is a bug. */ 996 BUG(); 997 return 0; 998} 999EXPORT_SYMBOL_GPL(vhost_log_write); 1000 1001static int vhost_update_used_flags(struct vhost_virtqueue *vq) 1002{ 1003 void __user *used; 1004 if (__put_user(vq->used_flags, &vq->used->flags) < 0) 1005 return -EFAULT; 1006 if (unlikely(vq->log_used)) { 1007 /* Make sure the flag is seen before log. */ 1008 smp_wmb(); 1009 /* Log used flag write. */ 1010 used = &vq->used->flags; 1011 log_write(vq->log_base, vq->log_addr + 1012 (used - (void __user *)vq->used), 1013 sizeof vq->used->flags); 1014 if (vq->log_ctx) 1015 eventfd_signal(vq->log_ctx, 1); 1016 } 1017 return 0; 1018} 1019 1020static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event) 1021{ 1022 if (__put_user(vq->avail_idx, vhost_avail_event(vq))) 1023 return -EFAULT; 1024 if (unlikely(vq->log_used)) { 1025 void __user *used; 1026 /* Make sure the event is seen before log. */ 1027 smp_wmb(); 1028 /* Log avail event write */ 1029 used = vhost_avail_event(vq); 1030 log_write(vq->log_base, vq->log_addr + 1031 (used - (void __user *)vq->used), 1032 sizeof *vhost_avail_event(vq)); 1033 if (vq->log_ctx) 1034 eventfd_signal(vq->log_ctx, 1); 1035 } 1036 return 0; 1037} 1038 1039int vhost_init_used(struct vhost_virtqueue *vq) 1040{ 1041 int r; 1042 if (!vq->private_data) 1043 return 0; 1044 1045 r = vhost_update_used_flags(vq); 1046 if (r) 1047 return r; 1048 vq->signalled_used_valid = false; 1049 return get_user(vq->last_used_idx, &vq->used->idx); 1050} 1051EXPORT_SYMBOL_GPL(vhost_init_used); 1052 1053static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len, 1054 struct iovec iov[], int iov_size) 1055{ 1056 const struct vhost_memory_region *reg; 1057 struct vhost_memory *mem; 1058 struct iovec *_iov; 1059 u64 s = 0; 1060 int ret = 0; 1061 1062 mem = vq->memory; 1063 while ((u64)len > s) { 1064 u64 size; 1065 if (unlikely(ret >= iov_size)) { 1066 ret = -ENOBUFS; 1067 break; 1068 } 1069 reg = find_region(mem, addr, len); 1070 if (unlikely(!reg)) { 1071 ret = -EFAULT; 1072 break; 1073 } 1074 _iov = iov + ret; 1075 size = reg->memory_size - addr + reg->guest_phys_addr; 1076 _iov->iov_len = min((u64)len - s, size); 1077 _iov->iov_base = (void __user *)(unsigned long) 1078 (reg->userspace_addr + addr - reg->guest_phys_addr); 1079 s += size; 1080 addr += size; 1081 ++ret; 1082 } 1083 1084 return ret; 1085} 1086 1087/* Each buffer in the virtqueues is actually a chain of descriptors. This 1088 * function returns the next descriptor in the chain, 1089 * or -1U if we're at the end. */ 1090static unsigned next_desc(struct vring_desc *desc) 1091{ 1092 unsigned int next; 1093 1094 /* If this descriptor says it doesn't chain, we're done. */ 1095 if (!(desc->flags & VRING_DESC_F_NEXT)) 1096 return -1U; 1097 1098 /* Check they're not leading us off end of descriptors. */ 1099 next = desc->next; 1100 /* Make sure compiler knows to grab that: we don't want it changing! */ 1101 /* We will use the result as an index in an array, so most 1102 * architectures only need a compiler barrier here. */ 1103 read_barrier_depends(); 1104 1105 return next; 1106} 1107 1108static int get_indirect(struct vhost_virtqueue *vq, 1109 struct iovec iov[], unsigned int iov_size, 1110 unsigned int *out_num, unsigned int *in_num, 1111 struct vhost_log *log, unsigned int *log_num, 1112 struct vring_desc *indirect) 1113{ 1114 struct vring_desc desc; 1115 unsigned int i = 0, count, found = 0; 1116 int ret; 1117 1118 /* Sanity check */ 1119 if (unlikely(indirect->len % sizeof desc)) { 1120 vq_err(vq, "Invalid length in indirect descriptor: " 1121 "len 0x%llx not multiple of 0x%zx\n", 1122 (unsigned long long)indirect->len, 1123 sizeof desc); 1124 return -EINVAL; 1125 } 1126 1127 ret = translate_desc(vq, indirect->addr, indirect->len, vq->indirect, 1128 UIO_MAXIOV); 1129 if (unlikely(ret < 0)) { 1130 vq_err(vq, "Translation failure %d in indirect.\n", ret); 1131 return ret; 1132 } 1133 1134 /* We will use the result as an address to read from, so most 1135 * architectures only need a compiler barrier here. */ 1136 read_barrier_depends(); 1137 1138 count = indirect->len / sizeof desc; 1139 /* Buffers are chained via a 16 bit next field, so 1140 * we can have at most 2^16 of these. */ 1141 if (unlikely(count > USHRT_MAX + 1)) { 1142 vq_err(vq, "Indirect buffer length too big: %d\n", 1143 indirect->len); 1144 return -E2BIG; 1145 } 1146 1147 do { 1148 unsigned iov_count = *in_num + *out_num; 1149 if (unlikely(++found > count)) { 1150 vq_err(vq, "Loop detected: last one at %u " 1151 "indirect size %u\n", 1152 i, count); 1153 return -EINVAL; 1154 } 1155 if (unlikely(memcpy_fromiovec((unsigned char *)&desc, 1156 vq->indirect, sizeof desc))) { 1157 vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n", 1158 i, (size_t)indirect->addr + i * sizeof desc); 1159 return -EINVAL; 1160 } 1161 if (unlikely(desc.flags & VRING_DESC_F_INDIRECT)) { 1162 vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n", 1163 i, (size_t)indirect->addr + i * sizeof desc); 1164 return -EINVAL; 1165 } 1166 1167 ret = translate_desc(vq, desc.addr, desc.len, iov + iov_count, 1168 iov_size - iov_count); 1169 if (unlikely(ret < 0)) { 1170 vq_err(vq, "Translation failure %d indirect idx %d\n", 1171 ret, i); 1172 return ret; 1173 } 1174 /* If this is an input descriptor, increment that count. */ 1175 if (desc.flags & VRING_DESC_F_WRITE) { 1176 *in_num += ret; 1177 if (unlikely(log)) { 1178 log[*log_num].addr = desc.addr; 1179 log[*log_num].len = desc.len; 1180 ++*log_num; 1181 } 1182 } else { 1183 /* If it's an output descriptor, they're all supposed 1184 * to come before any input descriptors. */ 1185 if (unlikely(*in_num)) { 1186 vq_err(vq, "Indirect descriptor " 1187 "has out after in: idx %d\n", i); 1188 return -EINVAL; 1189 } 1190 *out_num += ret; 1191 } 1192 } while ((i = next_desc(&desc)) != -1); 1193 return 0; 1194} 1195 1196/* This looks in the virtqueue and for the first available buffer, and converts 1197 * it to an iovec for convenient access. Since descriptors consist of some 1198 * number of output then some number of input descriptors, it's actually two 1199 * iovecs, but we pack them into one and note how many of each there were. 1200 * 1201 * This function returns the descriptor number found, or vq->num (which is 1202 * never a valid descriptor number) if none was found. A negative code is 1203 * returned on error. */ 1204int vhost_get_vq_desc(struct vhost_virtqueue *vq, 1205 struct iovec iov[], unsigned int iov_size, 1206 unsigned int *out_num, unsigned int *in_num, 1207 struct vhost_log *log, unsigned int *log_num) 1208{ 1209 struct vring_desc desc; 1210 unsigned int i, head, found = 0; 1211 u16 last_avail_idx; 1212 int ret; 1213 1214 /* Check it isn't doing very strange things with descriptor numbers. */ 1215 last_avail_idx = vq->last_avail_idx; 1216 if (unlikely(__get_user(vq->avail_idx, &vq->avail->idx))) { 1217 vq_err(vq, "Failed to access avail idx at %p\n", 1218 &vq->avail->idx); 1219 return -EFAULT; 1220 } 1221 1222 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) { 1223 vq_err(vq, "Guest moved used index from %u to %u", 1224 last_avail_idx, vq->avail_idx); 1225 return -EFAULT; 1226 } 1227 1228 /* If there's nothing new since last we looked, return invalid. */ 1229 if (vq->avail_idx == last_avail_idx) 1230 return vq->num; 1231 1232 /* Only get avail ring entries after they have been exposed by guest. */ 1233 smp_rmb(); 1234 1235 /* Grab the next descriptor number they're advertising, and increment 1236 * the index we've seen. */ 1237 if (unlikely(__get_user(head, 1238 &vq->avail->ring[last_avail_idx % vq->num]))) { 1239 vq_err(vq, "Failed to read head: idx %d address %p\n", 1240 last_avail_idx, 1241 &vq->avail->ring[last_avail_idx % vq->num]); 1242 return -EFAULT; 1243 } 1244 1245 /* If their number is silly, that's an error. */ 1246 if (unlikely(head >= vq->num)) { 1247 vq_err(vq, "Guest says index %u > %u is available", 1248 head, vq->num); 1249 return -EINVAL; 1250 } 1251 1252 /* When we start there are none of either input nor output. */ 1253 *out_num = *in_num = 0; 1254 if (unlikely(log)) 1255 *log_num = 0; 1256 1257 i = head; 1258 do { 1259 unsigned iov_count = *in_num + *out_num; 1260 if (unlikely(i >= vq->num)) { 1261 vq_err(vq, "Desc index is %u > %u, head = %u", 1262 i, vq->num, head); 1263 return -EINVAL; 1264 } 1265 if (unlikely(++found > vq->num)) { 1266 vq_err(vq, "Loop detected: last one at %u " 1267 "vq size %u head %u\n", 1268 i, vq->num, head); 1269 return -EINVAL; 1270 } 1271 ret = __copy_from_user(&desc, vq->desc + i, sizeof desc); 1272 if (unlikely(ret)) { 1273 vq_err(vq, "Failed to get descriptor: idx %d addr %p\n", 1274 i, vq->desc + i); 1275 return -EFAULT; 1276 } 1277 if (desc.flags & VRING_DESC_F_INDIRECT) { 1278 ret = get_indirect(vq, iov, iov_size, 1279 out_num, in_num, 1280 log, log_num, &desc); 1281 if (unlikely(ret < 0)) { 1282 vq_err(vq, "Failure detected " 1283 "in indirect descriptor at idx %d\n", i); 1284 return ret; 1285 } 1286 continue; 1287 } 1288 1289 ret = translate_desc(vq, desc.addr, desc.len, iov + iov_count, 1290 iov_size - iov_count); 1291 if (unlikely(ret < 0)) { 1292 vq_err(vq, "Translation failure %d descriptor idx %d\n", 1293 ret, i); 1294 return ret; 1295 } 1296 if (desc.flags & VRING_DESC_F_WRITE) { 1297 /* If this is an input descriptor, 1298 * increment that count. */ 1299 *in_num += ret; 1300 if (unlikely(log)) { 1301 log[*log_num].addr = desc.addr; 1302 log[*log_num].len = desc.len; 1303 ++*log_num; 1304 } 1305 } else { 1306 /* If it's an output descriptor, they're all supposed 1307 * to come before any input descriptors. */ 1308 if (unlikely(*in_num)) { 1309 vq_err(vq, "Descriptor has out after in: " 1310 "idx %d\n", i); 1311 return -EINVAL; 1312 } 1313 *out_num += ret; 1314 } 1315 } while ((i = next_desc(&desc)) != -1); 1316 1317 /* On success, increment avail index. */ 1318 vq->last_avail_idx++; 1319 1320 /* Assume notifications from guest are disabled at this point, 1321 * if they aren't we would need to update avail_event index. */ 1322 BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY)); 1323 return head; 1324} 1325EXPORT_SYMBOL_GPL(vhost_get_vq_desc); 1326 1327/* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */ 1328void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n) 1329{ 1330 vq->last_avail_idx -= n; 1331} 1332EXPORT_SYMBOL_GPL(vhost_discard_vq_desc); 1333 1334/* After we've used one of their buffers, we tell them about it. We'll then 1335 * want to notify the guest, using eventfd. */ 1336int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len) 1337{ 1338 struct vring_used_elem heads = { head, len }; 1339 1340 return vhost_add_used_n(vq, &heads, 1); 1341} 1342EXPORT_SYMBOL_GPL(vhost_add_used); 1343 1344static int __vhost_add_used_n(struct vhost_virtqueue *vq, 1345 struct vring_used_elem *heads, 1346 unsigned count) 1347{ 1348 struct vring_used_elem __user *used; 1349 u16 old, new; 1350 int start; 1351 1352 start = vq->last_used_idx % vq->num; 1353 used = vq->used->ring + start; 1354 if (count == 1) { 1355 if (__put_user(heads[0].id, &used->id)) { 1356 vq_err(vq, "Failed to write used id"); 1357 return -EFAULT; 1358 } 1359 if (__put_user(heads[0].len, &used->len)) { 1360 vq_err(vq, "Failed to write used len"); 1361 return -EFAULT; 1362 } 1363 } else if (__copy_to_user(used, heads, count * sizeof *used)) { 1364 vq_err(vq, "Failed to write used"); 1365 return -EFAULT; 1366 } 1367 if (unlikely(vq->log_used)) { 1368 /* Make sure data is seen before log. */ 1369 smp_wmb(); 1370 /* Log used ring entry write. */ 1371 log_write(vq->log_base, 1372 vq->log_addr + 1373 ((void __user *)used - (void __user *)vq->used), 1374 count * sizeof *used); 1375 } 1376 old = vq->last_used_idx; 1377 new = (vq->last_used_idx += count); 1378 /* If the driver never bothers to signal in a very long while, 1379 * used index might wrap around. If that happens, invalidate 1380 * signalled_used index we stored. TODO: make sure driver 1381 * signals at least once in 2^16 and remove this. */ 1382 if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old))) 1383 vq->signalled_used_valid = false; 1384 return 0; 1385} 1386 1387/* After we've used one of their buffers, we tell them about it. We'll then 1388 * want to notify the guest, using eventfd. */ 1389int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads, 1390 unsigned count) 1391{ 1392 int start, n, r; 1393 1394 start = vq->last_used_idx % vq->num; 1395 n = vq->num - start; 1396 if (n < count) { 1397 r = __vhost_add_used_n(vq, heads, n); 1398 if (r < 0) 1399 return r; 1400 heads += n; 1401 count -= n; 1402 } 1403 r = __vhost_add_used_n(vq, heads, count); 1404 1405 /* Make sure buffer is written before we update index. */ 1406 smp_wmb(); 1407 if (put_user(vq->last_used_idx, &vq->used->idx)) { 1408 vq_err(vq, "Failed to increment used idx"); 1409 return -EFAULT; 1410 } 1411 if (unlikely(vq->log_used)) { 1412 /* Log used index update. */ 1413 log_write(vq->log_base, 1414 vq->log_addr + offsetof(struct vring_used, idx), 1415 sizeof vq->used->idx); 1416 if (vq->log_ctx) 1417 eventfd_signal(vq->log_ctx, 1); 1418 } 1419 return r; 1420} 1421EXPORT_SYMBOL_GPL(vhost_add_used_n); 1422 1423static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) 1424{ 1425 __u16 old, new, event; 1426 bool v; 1427 /* Flush out used index updates. This is paired 1428 * with the barrier that the Guest executes when enabling 1429 * interrupts. */ 1430 smp_mb(); 1431 1432 if (vhost_has_feature(vq, VIRTIO_F_NOTIFY_ON_EMPTY) && 1433 unlikely(vq->avail_idx == vq->last_avail_idx)) 1434 return true; 1435 1436 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) { 1437 __u16 flags; 1438 if (__get_user(flags, &vq->avail->flags)) { 1439 vq_err(vq, "Failed to get flags"); 1440 return true; 1441 } 1442 return !(flags & VRING_AVAIL_F_NO_INTERRUPT); 1443 } 1444 old = vq->signalled_used; 1445 v = vq->signalled_used_valid; 1446 new = vq->signalled_used = vq->last_used_idx; 1447 vq->signalled_used_valid = true; 1448 1449 if (unlikely(!v)) 1450 return true; 1451 1452 if (get_user(event, vhost_used_event(vq))) { 1453 vq_err(vq, "Failed to get used event idx"); 1454 return true; 1455 } 1456 return vring_need_event(event, new, old); 1457} 1458 1459/* This actually signals the guest, using eventfd. */ 1460void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq) 1461{ 1462 /* Signal the Guest tell them we used something up. */ 1463 if (vq->call_ctx && vhost_notify(dev, vq)) 1464 eventfd_signal(vq->call_ctx, 1); 1465} 1466EXPORT_SYMBOL_GPL(vhost_signal); 1467 1468/* And here's the combo meal deal. Supersize me! */ 1469void vhost_add_used_and_signal(struct vhost_dev *dev, 1470 struct vhost_virtqueue *vq, 1471 unsigned int head, int len) 1472{ 1473 vhost_add_used(vq, head, len); 1474 vhost_signal(dev, vq); 1475} 1476EXPORT_SYMBOL_GPL(vhost_add_used_and_signal); 1477 1478/* multi-buffer version of vhost_add_used_and_signal */ 1479void vhost_add_used_and_signal_n(struct vhost_dev *dev, 1480 struct vhost_virtqueue *vq, 1481 struct vring_used_elem *heads, unsigned count) 1482{ 1483 vhost_add_used_n(vq, heads, count); 1484 vhost_signal(dev, vq); 1485} 1486EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n); 1487 1488/* OK, now we need to know about added descriptors. */ 1489bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) 1490{ 1491 u16 avail_idx; 1492 int r; 1493 1494 if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY)) 1495 return false; 1496 vq->used_flags &= ~VRING_USED_F_NO_NOTIFY; 1497 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) { 1498 r = vhost_update_used_flags(vq); 1499 if (r) { 1500 vq_err(vq, "Failed to enable notification at %p: %d\n", 1501 &vq->used->flags, r); 1502 return false; 1503 } 1504 } else { 1505 r = vhost_update_avail_event(vq, vq->avail_idx); 1506 if (r) { 1507 vq_err(vq, "Failed to update avail event index at %p: %d\n", 1508 vhost_avail_event(vq), r); 1509 return false; 1510 } 1511 } 1512 /* They could have slipped one in as we were doing that: make 1513 * sure it's written, then check again. */ 1514 smp_mb(); 1515 r = __get_user(avail_idx, &vq->avail->idx); 1516 if (r) { 1517 vq_err(vq, "Failed to check avail idx at %p: %d\n", 1518 &vq->avail->idx, r); 1519 return false; 1520 } 1521 1522 return avail_idx != vq->avail_idx; 1523} 1524EXPORT_SYMBOL_GPL(vhost_enable_notify); 1525 1526/* We don't need to be notified again. */ 1527void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) 1528{ 1529 int r; 1530 1531 if (vq->used_flags & VRING_USED_F_NO_NOTIFY) 1532 return; 1533 vq->used_flags |= VRING_USED_F_NO_NOTIFY; 1534 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) { 1535 r = vhost_update_used_flags(vq); 1536 if (r) 1537 vq_err(vq, "Failed to enable notification at %p: %d\n", 1538 &vq->used->flags, r); 1539 } 1540} 1541EXPORT_SYMBOL_GPL(vhost_disable_notify); 1542 1543static int __init vhost_init(void) 1544{ 1545 return 0; 1546} 1547 1548static void __exit vhost_exit(void) 1549{ 1550} 1551 1552module_init(vhost_init); 1553module_exit(vhost_exit); 1554 1555MODULE_VERSION("0.0.1"); 1556MODULE_LICENSE("GPL v2"); 1557MODULE_AUTHOR("Michael S. Tsirkin"); 1558MODULE_DESCRIPTION("Host kernel accelerator for virtio"); 1559