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) ((__virtio16 __user *)&vq->avail->ring[vq->num]) 37#define vhost_avail_event(vq) ((__virtio16 __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 } 716 717 /* 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} 830EXPORT_SYMBOL_GPL(vhost_vring_ioctl); 831 832/* Caller must have device mutex */ 833long 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 d->log_file = eventfp; 890 ctx = d->log_ctx; 891 d->log_ctx = eventfp ? 892 eventfd_ctx_fileget(eventfp) : NULL; 893 } else 894 filep = eventfp; 895 for (i = 0; i < d->nvqs; ++i) { 896 mutex_lock(&d->vqs[i]->mutex); 897 d->vqs[i]->log_ctx = d->log_ctx; 898 mutex_unlock(&d->vqs[i]->mutex); 899 } 900 if (ctx) 901 eventfd_ctx_put(ctx); 902 if (filep) 903 fput(filep); 904 break; 905 default: 906 r = -ENOIOCTLCMD; 907 break; 908 } 909done: 910 return r; 911} 912EXPORT_SYMBOL_GPL(vhost_dev_ioctl); 913 914static const struct vhost_memory_region *find_region(struct vhost_memory *mem, 915 __u64 addr, __u32 len) 916{ 917 struct vhost_memory_region *reg; 918 int i; 919 920 /* linear search is not brilliant, but we really have on the order of 6 921 * regions in practice */ 922 for (i = 0; i < mem->nregions; ++i) { 923 reg = mem->regions + i; 924 if (reg->guest_phys_addr <= addr && 925 reg->guest_phys_addr + reg->memory_size - 1 >= addr) 926 return reg; 927 } 928 return NULL; 929} 930 931/* TODO: This is really inefficient. We need something like get_user() 932 * (instruction directly accesses the data, with an exception table entry 933 * returning -EFAULT). See Documentation/x86/exception-tables.txt. 934 */ 935static int set_bit_to_user(int nr, void __user *addr) 936{ 937 unsigned long log = (unsigned long)addr; 938 struct page *page; 939 void *base; 940 int bit = nr + (log % PAGE_SIZE) * 8; 941 int r; 942 943 r = get_user_pages_fast(log, 1, 1, &page); 944 if (r < 0) 945 return r; 946 BUG_ON(r != 1); 947 base = kmap_atomic(page); 948 set_bit(bit, base); 949 kunmap_atomic(base); 950 set_page_dirty_lock(page); 951 put_page(page); 952 return 0; 953} 954 955static int log_write(void __user *log_base, 956 u64 write_address, u64 write_length) 957{ 958 u64 write_page = write_address / VHOST_PAGE_SIZE; 959 int r; 960 961 if (!write_length) 962 return 0; 963 write_length += write_address % VHOST_PAGE_SIZE; 964 for (;;) { 965 u64 base = (u64)(unsigned long)log_base; 966 u64 log = base + write_page / 8; 967 int bit = write_page % 8; 968 if ((u64)(unsigned long)log != log) 969 return -EFAULT; 970 r = set_bit_to_user(bit, (void __user *)(unsigned long)log); 971 if (r < 0) 972 return r; 973 if (write_length <= VHOST_PAGE_SIZE) 974 break; 975 write_length -= VHOST_PAGE_SIZE; 976 write_page += 1; 977 } 978 return r; 979} 980 981int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log, 982 unsigned int log_num, u64 len) 983{ 984 int i, r; 985 986 /* Make sure data written is seen before log. */ 987 smp_wmb(); 988 for (i = 0; i < log_num; ++i) { 989 u64 l = min(log[i].len, len); 990 r = log_write(vq->log_base, log[i].addr, l); 991 if (r < 0) 992 return r; 993 len -= l; 994 if (!len) { 995 if (vq->log_ctx) 996 eventfd_signal(vq->log_ctx, 1); 997 return 0; 998 } 999 } 1000 /* Length written exceeds what we have stored. This is a bug. */ 1001 BUG(); 1002 return 0; 1003} 1004EXPORT_SYMBOL_GPL(vhost_log_write); 1005 1006static int vhost_update_used_flags(struct vhost_virtqueue *vq) 1007{ 1008 void __user *used; 1009 if (__put_user(cpu_to_vhost16(vq, vq->used_flags), &vq->used->flags) < 0) 1010 return -EFAULT; 1011 if (unlikely(vq->log_used)) { 1012 /* Make sure the flag is seen before log. */ 1013 smp_wmb(); 1014 /* Log used flag write. */ 1015 used = &vq->used->flags; 1016 log_write(vq->log_base, vq->log_addr + 1017 (used - (void __user *)vq->used), 1018 sizeof vq->used->flags); 1019 if (vq->log_ctx) 1020 eventfd_signal(vq->log_ctx, 1); 1021 } 1022 return 0; 1023} 1024 1025static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event) 1026{ 1027 if (__put_user(cpu_to_vhost16(vq, vq->avail_idx), vhost_avail_event(vq))) 1028 return -EFAULT; 1029 if (unlikely(vq->log_used)) { 1030 void __user *used; 1031 /* Make sure the event is seen before log. */ 1032 smp_wmb(); 1033 /* Log avail event write */ 1034 used = vhost_avail_event(vq); 1035 log_write(vq->log_base, vq->log_addr + 1036 (used - (void __user *)vq->used), 1037 sizeof *vhost_avail_event(vq)); 1038 if (vq->log_ctx) 1039 eventfd_signal(vq->log_ctx, 1); 1040 } 1041 return 0; 1042} 1043 1044int vhost_init_used(struct vhost_virtqueue *vq) 1045{ 1046 __virtio16 last_used_idx; 1047 int r; 1048 if (!vq->private_data) 1049 return 0; 1050 1051 r = vhost_update_used_flags(vq); 1052 if (r) 1053 return r; 1054 vq->signalled_used_valid = false; 1055 if (!access_ok(VERIFY_READ, &vq->used->idx, sizeof vq->used->idx)) 1056 return -EFAULT; 1057 r = __get_user(last_used_idx, &vq->used->idx); 1058 if (r) 1059 return r; 1060 vq->last_used_idx = vhost16_to_cpu(vq, last_used_idx); 1061 return 0; 1062} 1063EXPORT_SYMBOL_GPL(vhost_init_used); 1064 1065static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len, 1066 struct iovec iov[], int iov_size) 1067{ 1068 const struct vhost_memory_region *reg; 1069 struct vhost_memory *mem; 1070 struct iovec *_iov; 1071 u64 s = 0; 1072 int ret = 0; 1073 1074 mem = vq->memory; 1075 while ((u64)len > s) { 1076 u64 size; 1077 if (unlikely(ret >= iov_size)) { 1078 ret = -ENOBUFS; 1079 break; 1080 } 1081 reg = find_region(mem, addr, len); 1082 if (unlikely(!reg)) { 1083 ret = -EFAULT; 1084 break; 1085 } 1086 _iov = iov + ret; 1087 size = reg->memory_size - addr + reg->guest_phys_addr; 1088 _iov->iov_len = min((u64)len - s, size); 1089 _iov->iov_base = (void __user *)(unsigned long) 1090 (reg->userspace_addr + addr - reg->guest_phys_addr); 1091 s += size; 1092 addr += size; 1093 ++ret; 1094 } 1095 1096 return ret; 1097} 1098 1099/* Each buffer in the virtqueues is actually a chain of descriptors. This 1100 * function returns the next descriptor in the chain, 1101 * or -1U if we're at the end. */ 1102static unsigned next_desc(struct vhost_virtqueue *vq, struct vring_desc *desc) 1103{ 1104 unsigned int next; 1105 1106 /* If this descriptor says it doesn't chain, we're done. */ 1107 if (!(desc->flags & cpu_to_vhost16(vq, VRING_DESC_F_NEXT))) 1108 return -1U; 1109 1110 /* Check they're not leading us off end of descriptors. */ 1111 next = vhost16_to_cpu(vq, desc->next); 1112 /* Make sure compiler knows to grab that: we don't want it changing! */ 1113 /* We will use the result as an index in an array, so most 1114 * architectures only need a compiler barrier here. */ 1115 read_barrier_depends(); 1116 1117 return next; 1118} 1119 1120static int get_indirect(struct vhost_virtqueue *vq, 1121 struct iovec iov[], unsigned int iov_size, 1122 unsigned int *out_num, unsigned int *in_num, 1123 struct vhost_log *log, unsigned int *log_num, 1124 struct vring_desc *indirect) 1125{ 1126 struct vring_desc desc; 1127 unsigned int i = 0, count, found = 0; 1128 u32 len = vhost32_to_cpu(vq, indirect->len); 1129 struct iov_iter from; 1130 int ret; 1131 1132 /* Sanity check */ 1133 if (unlikely(len % sizeof desc)) { 1134 vq_err(vq, "Invalid length in indirect descriptor: " 1135 "len 0x%llx not multiple of 0x%zx\n", 1136 (unsigned long long)len, 1137 sizeof desc); 1138 return -EINVAL; 1139 } 1140 1141 ret = translate_desc(vq, vhost64_to_cpu(vq, indirect->addr), len, vq->indirect, 1142 UIO_MAXIOV); 1143 if (unlikely(ret < 0)) { 1144 vq_err(vq, "Translation failure %d in indirect.\n", ret); 1145 return ret; 1146 } 1147 iov_iter_init(&from, READ, vq->indirect, ret, len); 1148 1149 /* We will use the result as an address to read from, so most 1150 * architectures only need a compiler barrier here. */ 1151 read_barrier_depends(); 1152 1153 count = len / sizeof desc; 1154 /* Buffers are chained via a 16 bit next field, so 1155 * we can have at most 2^16 of these. */ 1156 if (unlikely(count > USHRT_MAX + 1)) { 1157 vq_err(vq, "Indirect buffer length too big: %d\n", 1158 indirect->len); 1159 return -E2BIG; 1160 } 1161 1162 do { 1163 unsigned iov_count = *in_num + *out_num; 1164 if (unlikely(++found > count)) { 1165 vq_err(vq, "Loop detected: last one at %u " 1166 "indirect size %u\n", 1167 i, count); 1168 return -EINVAL; 1169 } 1170 if (unlikely(copy_from_iter(&desc, sizeof(desc), &from) != 1171 sizeof(desc))) { 1172 vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n", 1173 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc); 1174 return -EINVAL; 1175 } 1176 if (unlikely(desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT))) { 1177 vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n", 1178 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc); 1179 return -EINVAL; 1180 } 1181 1182 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr), 1183 vhost32_to_cpu(vq, desc.len), iov + iov_count, 1184 iov_size - iov_count); 1185 if (unlikely(ret < 0)) { 1186 vq_err(vq, "Translation failure %d indirect idx %d\n", 1187 ret, i); 1188 return ret; 1189 } 1190 /* If this is an input descriptor, increment that count. */ 1191 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE)) { 1192 *in_num += ret; 1193 if (unlikely(log)) { 1194 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr); 1195 log[*log_num].len = vhost32_to_cpu(vq, desc.len); 1196 ++*log_num; 1197 } 1198 } else { 1199 /* If it's an output descriptor, they're all supposed 1200 * to come before any input descriptors. */ 1201 if (unlikely(*in_num)) { 1202 vq_err(vq, "Indirect descriptor " 1203 "has out after in: idx %d\n", i); 1204 return -EINVAL; 1205 } 1206 *out_num += ret; 1207 } 1208 } while ((i = next_desc(vq, &desc)) != -1); 1209 return 0; 1210} 1211 1212/* This looks in the virtqueue and for the first available buffer, and converts 1213 * it to an iovec for convenient access. Since descriptors consist of some 1214 * number of output then some number of input descriptors, it's actually two 1215 * iovecs, but we pack them into one and note how many of each there were. 1216 * 1217 * This function returns the descriptor number found, or vq->num (which is 1218 * never a valid descriptor number) if none was found. A negative code is 1219 * returned on error. */ 1220int vhost_get_vq_desc(struct vhost_virtqueue *vq, 1221 struct iovec iov[], unsigned int iov_size, 1222 unsigned int *out_num, unsigned int *in_num, 1223 struct vhost_log *log, unsigned int *log_num) 1224{ 1225 struct vring_desc desc; 1226 unsigned int i, head, found = 0; 1227 u16 last_avail_idx; 1228 __virtio16 avail_idx; 1229 __virtio16 ring_head; 1230 int ret; 1231 1232 /* Check it isn't doing very strange things with descriptor numbers. */ 1233 last_avail_idx = vq->last_avail_idx; 1234 if (unlikely(__get_user(avail_idx, &vq->avail->idx))) { 1235 vq_err(vq, "Failed to access avail idx at %p\n", 1236 &vq->avail->idx); 1237 return -EFAULT; 1238 } 1239 vq->avail_idx = vhost16_to_cpu(vq, avail_idx); 1240 1241 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) { 1242 vq_err(vq, "Guest moved used index from %u to %u", 1243 last_avail_idx, vq->avail_idx); 1244 return -EFAULT; 1245 } 1246 1247 /* If there's nothing new since last we looked, return invalid. */ 1248 if (vq->avail_idx == last_avail_idx) 1249 return vq->num; 1250 1251 /* Only get avail ring entries after they have been exposed by guest. */ 1252 smp_rmb(); 1253 1254 /* Grab the next descriptor number they're advertising, and increment 1255 * the index we've seen. */ 1256 if (unlikely(__get_user(ring_head, 1257 &vq->avail->ring[last_avail_idx % vq->num]))) { 1258 vq_err(vq, "Failed to read head: idx %d address %p\n", 1259 last_avail_idx, 1260 &vq->avail->ring[last_avail_idx % vq->num]); 1261 return -EFAULT; 1262 } 1263 1264 head = vhost16_to_cpu(vq, ring_head); 1265 1266 /* If their number is silly, that's an error. */ 1267 if (unlikely(head >= vq->num)) { 1268 vq_err(vq, "Guest says index %u > %u is available", 1269 head, vq->num); 1270 return -EINVAL; 1271 } 1272 1273 /* When we start there are none of either input nor output. */ 1274 *out_num = *in_num = 0; 1275 if (unlikely(log)) 1276 *log_num = 0; 1277 1278 i = head; 1279 do { 1280 unsigned iov_count = *in_num + *out_num; 1281 if (unlikely(i >= vq->num)) { 1282 vq_err(vq, "Desc index is %u > %u, head = %u", 1283 i, vq->num, head); 1284 return -EINVAL; 1285 } 1286 if (unlikely(++found > vq->num)) { 1287 vq_err(vq, "Loop detected: last one at %u " 1288 "vq size %u head %u\n", 1289 i, vq->num, head); 1290 return -EINVAL; 1291 } 1292 ret = __copy_from_user(&desc, vq->desc + i, sizeof desc); 1293 if (unlikely(ret)) { 1294 vq_err(vq, "Failed to get descriptor: idx %d addr %p\n", 1295 i, vq->desc + i); 1296 return -EFAULT; 1297 } 1298 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT)) { 1299 ret = get_indirect(vq, iov, iov_size, 1300 out_num, in_num, 1301 log, log_num, &desc); 1302 if (unlikely(ret < 0)) { 1303 vq_err(vq, "Failure detected " 1304 "in indirect descriptor at idx %d\n", i); 1305 return ret; 1306 } 1307 continue; 1308 } 1309 1310 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr), 1311 vhost32_to_cpu(vq, desc.len), iov + iov_count, 1312 iov_size - iov_count); 1313 if (unlikely(ret < 0)) { 1314 vq_err(vq, "Translation failure %d descriptor idx %d\n", 1315 ret, i); 1316 return ret; 1317 } 1318 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE)) { 1319 /* If this is an input descriptor, 1320 * increment that count. */ 1321 *in_num += ret; 1322 if (unlikely(log)) { 1323 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr); 1324 log[*log_num].len = vhost32_to_cpu(vq, desc.len); 1325 ++*log_num; 1326 } 1327 } else { 1328 /* If it's an output descriptor, they're all supposed 1329 * to come before any input descriptors. */ 1330 if (unlikely(*in_num)) { 1331 vq_err(vq, "Descriptor has out after in: " 1332 "idx %d\n", i); 1333 return -EINVAL; 1334 } 1335 *out_num += ret; 1336 } 1337 } while ((i = next_desc(vq, &desc)) != -1); 1338 1339 /* On success, increment avail index. */ 1340 vq->last_avail_idx++; 1341 1342 /* Assume notifications from guest are disabled at this point, 1343 * if they aren't we would need to update avail_event index. */ 1344 BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY)); 1345 return head; 1346} 1347EXPORT_SYMBOL_GPL(vhost_get_vq_desc); 1348 1349/* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */ 1350void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n) 1351{ 1352 vq->last_avail_idx -= n; 1353} 1354EXPORT_SYMBOL_GPL(vhost_discard_vq_desc); 1355 1356/* After we've used one of their buffers, we tell them about it. We'll then 1357 * want to notify the guest, using eventfd. */ 1358int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len) 1359{ 1360 struct vring_used_elem heads = { 1361 cpu_to_vhost32(vq, head), 1362 cpu_to_vhost32(vq, len) 1363 }; 1364 1365 return vhost_add_used_n(vq, &heads, 1); 1366} 1367EXPORT_SYMBOL_GPL(vhost_add_used); 1368 1369static int __vhost_add_used_n(struct vhost_virtqueue *vq, 1370 struct vring_used_elem *heads, 1371 unsigned count) 1372{ 1373 struct vring_used_elem __user *used; 1374 u16 old, new; 1375 int start; 1376 1377 start = vq->last_used_idx % vq->num; 1378 used = vq->used->ring + start; 1379 if (count == 1) { 1380 if (__put_user(heads[0].id, &used->id)) { 1381 vq_err(vq, "Failed to write used id"); 1382 return -EFAULT; 1383 } 1384 if (__put_user(heads[0].len, &used->len)) { 1385 vq_err(vq, "Failed to write used len"); 1386 return -EFAULT; 1387 } 1388 } else if (__copy_to_user(used, heads, count * sizeof *used)) { 1389 vq_err(vq, "Failed to write used"); 1390 return -EFAULT; 1391 } 1392 if (unlikely(vq->log_used)) { 1393 /* Make sure data is seen before log. */ 1394 smp_wmb(); 1395 /* Log used ring entry write. */ 1396 log_write(vq->log_base, 1397 vq->log_addr + 1398 ((void __user *)used - (void __user *)vq->used), 1399 count * sizeof *used); 1400 } 1401 old = vq->last_used_idx; 1402 new = (vq->last_used_idx += count); 1403 /* If the driver never bothers to signal in a very long while, 1404 * used index might wrap around. If that happens, invalidate 1405 * signalled_used index we stored. TODO: make sure driver 1406 * signals at least once in 2^16 and remove this. */ 1407 if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old))) 1408 vq->signalled_used_valid = false; 1409 return 0; 1410} 1411 1412/* After we've used one of their buffers, we tell them about it. We'll then 1413 * want to notify the guest, using eventfd. */ 1414int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads, 1415 unsigned count) 1416{ 1417 int start, n, r; 1418 1419 start = vq->last_used_idx % vq->num; 1420 n = vq->num - start; 1421 if (n < count) { 1422 r = __vhost_add_used_n(vq, heads, n); 1423 if (r < 0) 1424 return r; 1425 heads += n; 1426 count -= n; 1427 } 1428 r = __vhost_add_used_n(vq, heads, count); 1429 1430 /* Make sure buffer is written before we update index. */ 1431 smp_wmb(); 1432 if (__put_user(cpu_to_vhost16(vq, vq->last_used_idx), &vq->used->idx)) { 1433 vq_err(vq, "Failed to increment used idx"); 1434 return -EFAULT; 1435 } 1436 if (unlikely(vq->log_used)) { 1437 /* Log used index update. */ 1438 log_write(vq->log_base, 1439 vq->log_addr + offsetof(struct vring_used, idx), 1440 sizeof vq->used->idx); 1441 if (vq->log_ctx) 1442 eventfd_signal(vq->log_ctx, 1); 1443 } 1444 return r; 1445} 1446EXPORT_SYMBOL_GPL(vhost_add_used_n); 1447 1448static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) 1449{ 1450 __u16 old, new; 1451 __virtio16 event; 1452 bool v; 1453 /* Flush out used index updates. This is paired 1454 * with the barrier that the Guest executes when enabling 1455 * interrupts. */ 1456 smp_mb(); 1457 1458 if (vhost_has_feature(vq, VIRTIO_F_NOTIFY_ON_EMPTY) && 1459 unlikely(vq->avail_idx == vq->last_avail_idx)) 1460 return true; 1461 1462 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) { 1463 __virtio16 flags; 1464 if (__get_user(flags, &vq->avail->flags)) { 1465 vq_err(vq, "Failed to get flags"); 1466 return true; 1467 } 1468 return !(flags & cpu_to_vhost16(vq, VRING_AVAIL_F_NO_INTERRUPT)); 1469 } 1470 old = vq->signalled_used; 1471 v = vq->signalled_used_valid; 1472 new = vq->signalled_used = vq->last_used_idx; 1473 vq->signalled_used_valid = true; 1474 1475 if (unlikely(!v)) 1476 return true; 1477 1478 if (__get_user(event, vhost_used_event(vq))) { 1479 vq_err(vq, "Failed to get used event idx"); 1480 return true; 1481 } 1482 return vring_need_event(vhost16_to_cpu(vq, event), new, old); 1483} 1484 1485/* This actually signals the guest, using eventfd. */ 1486void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq) 1487{ 1488 /* Signal the Guest tell them we used something up. */ 1489 if (vq->call_ctx && vhost_notify(dev, vq)) 1490 eventfd_signal(vq->call_ctx, 1); 1491} 1492EXPORT_SYMBOL_GPL(vhost_signal); 1493 1494/* And here's the combo meal deal. Supersize me! */ 1495void vhost_add_used_and_signal(struct vhost_dev *dev, 1496 struct vhost_virtqueue *vq, 1497 unsigned int head, int len) 1498{ 1499 vhost_add_used(vq, head, len); 1500 vhost_signal(dev, vq); 1501} 1502EXPORT_SYMBOL_GPL(vhost_add_used_and_signal); 1503 1504/* multi-buffer version of vhost_add_used_and_signal */ 1505void vhost_add_used_and_signal_n(struct vhost_dev *dev, 1506 struct vhost_virtqueue *vq, 1507 struct vring_used_elem *heads, unsigned count) 1508{ 1509 vhost_add_used_n(vq, heads, count); 1510 vhost_signal(dev, vq); 1511} 1512EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n); 1513 1514/* OK, now we need to know about added descriptors. */ 1515bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) 1516{ 1517 __virtio16 avail_idx; 1518 int r; 1519 1520 if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY)) 1521 return false; 1522 vq->used_flags &= ~VRING_USED_F_NO_NOTIFY; 1523 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) { 1524 r = vhost_update_used_flags(vq); 1525 if (r) { 1526 vq_err(vq, "Failed to enable notification at %p: %d\n", 1527 &vq->used->flags, r); 1528 return false; 1529 } 1530 } else { 1531 r = vhost_update_avail_event(vq, vq->avail_idx); 1532 if (r) { 1533 vq_err(vq, "Failed to update avail event index at %p: %d\n", 1534 vhost_avail_event(vq), r); 1535 return false; 1536 } 1537 } 1538 /* They could have slipped one in as we were doing that: make 1539 * sure it's written, then check again. */ 1540 smp_mb(); 1541 r = __get_user(avail_idx, &vq->avail->idx); 1542 if (r) { 1543 vq_err(vq, "Failed to check avail idx at %p: %d\n", 1544 &vq->avail->idx, r); 1545 return false; 1546 } 1547 1548 return vhost16_to_cpu(vq, avail_idx) != vq->avail_idx; 1549} 1550EXPORT_SYMBOL_GPL(vhost_enable_notify); 1551 1552/* We don't need to be notified again. */ 1553void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) 1554{ 1555 int r; 1556 1557 if (vq->used_flags & VRING_USED_F_NO_NOTIFY) 1558 return; 1559 vq->used_flags |= VRING_USED_F_NO_NOTIFY; 1560 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) { 1561 r = vhost_update_used_flags(vq); 1562 if (r) 1563 vq_err(vq, "Failed to enable notification at %p: %d\n", 1564 &vq->used->flags, r); 1565 } 1566} 1567EXPORT_SYMBOL_GPL(vhost_disable_notify); 1568 1569static int __init vhost_init(void) 1570{ 1571 return 0; 1572} 1573 1574static void __exit vhost_exit(void) 1575{ 1576} 1577 1578module_init(vhost_init); 1579module_exit(vhost_exit); 1580 1581MODULE_VERSION("0.0.1"); 1582MODULE_LICENSE("GPL v2"); 1583MODULE_AUTHOR("Michael S. Tsirkin"); 1584MODULE_DESCRIPTION("Host kernel accelerator for virtio"); 1585