1 /* Copyright (C) 2009 Red Hat, Inc.
2 * Copyright (C) 2006 Rusty Russell IBM Corporation
4 * Author: Michael S. Tsirkin <mst@redhat.com>
6 * Inspiration, some code, and most witty comments come from
7 * Documentation/virtual/lguest/lguest.c, by Rusty Russell
9 * This work is licensed under the terms of the GNU GPL, version 2.
11 * Generic code for virtio server in host kernel.
14 #include <linux/eventfd.h>
15 #include <linux/vhost.h>
16 #include <linux/uio.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/vmalloc.h>
26 #include <linux/kthread.h>
27 #include <linux/cgroup.h>
28 #include <linux/module.h>
29 #include <linux/sort.h>
30 #include <linux/sched/mm.h>
31 #include <linux/sched/signal.h>
32 #include <linux/interval_tree_generic.h>
36 static ushort max_mem_regions = 64;
37 module_param(max_mem_regions, ushort, 0444);
38 MODULE_PARM_DESC(max_mem_regions,
39 "Maximum number of memory regions in memory map. (default: 64)");
40 static int max_iotlb_entries = 2048;
41 module_param(max_iotlb_entries, int, 0444);
42 MODULE_PARM_DESC(max_iotlb_entries,
43 "Maximum number of iotlb entries. (default: 2048)");
46 VHOST_MEMORY_F_LOG = 0x1,
49 #define vhost_used_event(vq) ((__virtio16 __user *)&vq->avail->ring[vq->num])
50 #define vhost_avail_event(vq) ((__virtio16 __user *)&vq->used->ring[vq->num])
52 INTERVAL_TREE_DEFINE(struct vhost_umem_node,
53 rb, __u64, __subtree_last,
54 START, LAST, static inline, vhost_umem_interval_tree);
56 #ifdef CONFIG_VHOST_CROSS_ENDIAN_LEGACY
57 static void vhost_disable_cross_endian(struct vhost_virtqueue *vq)
59 vq->user_be = !virtio_legacy_is_little_endian();
62 static void vhost_enable_cross_endian_big(struct vhost_virtqueue *vq)
67 static void vhost_enable_cross_endian_little(struct vhost_virtqueue *vq)
72 static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp)
74 struct vhost_vring_state s;
79 if (copy_from_user(&s, argp, sizeof(s)))
82 if (s.num != VHOST_VRING_LITTLE_ENDIAN &&
83 s.num != VHOST_VRING_BIG_ENDIAN)
86 if (s.num == VHOST_VRING_BIG_ENDIAN)
87 vhost_enable_cross_endian_big(vq);
89 vhost_enable_cross_endian_little(vq);
94 static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx,
97 struct vhost_vring_state s = {
102 if (copy_to_user(argp, &s, sizeof(s)))
108 static void vhost_init_is_le(struct vhost_virtqueue *vq)
110 /* Note for legacy virtio: user_be is initialized at reset time
111 * according to the host endianness. If userspace does not set an
112 * explicit endianness, the default behavior is native endian, as
113 * expected by legacy virtio.
115 vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1) || !vq->user_be;
118 static void vhost_disable_cross_endian(struct vhost_virtqueue *vq)
122 static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp)
127 static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx,
133 static void vhost_init_is_le(struct vhost_virtqueue *vq)
135 vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1)
136 || virtio_legacy_is_little_endian();
138 #endif /* CONFIG_VHOST_CROSS_ENDIAN_LEGACY */
140 static void vhost_reset_is_le(struct vhost_virtqueue *vq)
142 vhost_init_is_le(vq);
145 struct vhost_flush_struct {
146 struct vhost_work work;
147 struct completion wait_event;
150 static void vhost_flush_work(struct vhost_work *work)
152 struct vhost_flush_struct *s;
154 s = container_of(work, struct vhost_flush_struct, work);
155 complete(&s->wait_event);
158 static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh,
161 struct vhost_poll *poll;
163 poll = container_of(pt, struct vhost_poll, table);
165 add_wait_queue(wqh, &poll->wait);
168 static int vhost_poll_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync,
171 struct vhost_poll *poll = container_of(wait, struct vhost_poll, wait);
173 if (!(key_to_poll(key) & poll->mask))
176 vhost_poll_queue(poll);
180 void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn)
182 clear_bit(VHOST_WORK_QUEUED, &work->flags);
185 EXPORT_SYMBOL_GPL(vhost_work_init);
187 /* Init poll structure */
188 void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
189 __poll_t mask, struct vhost_dev *dev)
191 init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup);
192 init_poll_funcptr(&poll->table, vhost_poll_func);
197 vhost_work_init(&poll->work, fn);
199 EXPORT_SYMBOL_GPL(vhost_poll_init);
201 /* Start polling a file. We add ourselves to file's wait queue. The caller must
202 * keep a reference to a file until after vhost_poll_stop is called. */
203 int vhost_poll_start(struct vhost_poll *poll, struct file *file)
211 mask = file->f_op->poll(file, &poll->table);
213 vhost_poll_wakeup(&poll->wait, 0, 0, poll_to_key(mask));
214 if (mask & EPOLLERR) {
215 vhost_poll_stop(poll);
221 EXPORT_SYMBOL_GPL(vhost_poll_start);
223 /* Stop polling a file. After this function returns, it becomes safe to drop the
224 * file reference. You must also flush afterwards. */
225 void vhost_poll_stop(struct vhost_poll *poll)
228 remove_wait_queue(poll->wqh, &poll->wait);
232 EXPORT_SYMBOL_GPL(vhost_poll_stop);
234 void vhost_work_flush(struct vhost_dev *dev, struct vhost_work *work)
236 struct vhost_flush_struct flush;
239 init_completion(&flush.wait_event);
240 vhost_work_init(&flush.work, vhost_flush_work);
242 vhost_work_queue(dev, &flush.work);
243 wait_for_completion(&flush.wait_event);
246 EXPORT_SYMBOL_GPL(vhost_work_flush);
248 /* Flush any work that has been scheduled. When calling this, don't hold any
249 * locks that are also used by the callback. */
250 void vhost_poll_flush(struct vhost_poll *poll)
252 vhost_work_flush(poll->dev, &poll->work);
254 EXPORT_SYMBOL_GPL(vhost_poll_flush);
256 void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work)
261 if (!test_and_set_bit(VHOST_WORK_QUEUED, &work->flags)) {
262 /* We can only add the work to the list after we're
263 * sure it was not in the list.
264 * test_and_set_bit() implies a memory barrier.
266 llist_add(&work->node, &dev->work_list);
267 wake_up_process(dev->worker);
270 EXPORT_SYMBOL_GPL(vhost_work_queue);
272 /* A lockless hint for busy polling code to exit the loop */
273 bool vhost_has_work(struct vhost_dev *dev)
275 return !llist_empty(&dev->work_list);
277 EXPORT_SYMBOL_GPL(vhost_has_work);
279 void vhost_poll_queue(struct vhost_poll *poll)
281 vhost_work_queue(poll->dev, &poll->work);
283 EXPORT_SYMBOL_GPL(vhost_poll_queue);
285 static void __vhost_vq_meta_reset(struct vhost_virtqueue *vq)
289 for (j = 0; j < VHOST_NUM_ADDRS; j++)
290 vq->meta_iotlb[j] = NULL;
293 static void vhost_vq_meta_reset(struct vhost_dev *d)
297 for (i = 0; i < d->nvqs; ++i)
298 __vhost_vq_meta_reset(d->vqs[i]);
301 static void vhost_vq_reset(struct vhost_dev *dev,
302 struct vhost_virtqueue *vq)
308 vq->last_avail_idx = 0;
310 vq->last_used_idx = 0;
311 vq->signalled_used = 0;
312 vq->signalled_used_valid = false;
314 vq->log_used = false;
315 vq->log_addr = -1ull;
316 vq->private_data = NULL;
317 vq->acked_features = 0;
319 vq->error_ctx = NULL;
323 vhost_reset_is_le(vq);
324 vhost_disable_cross_endian(vq);
325 vq->busyloop_timeout = 0;
328 __vhost_vq_meta_reset(vq);
331 static int vhost_worker(void *data)
333 struct vhost_dev *dev = data;
334 struct vhost_work *work, *work_next;
335 struct llist_node *node;
336 mm_segment_t oldfs = get_fs();
342 /* mb paired w/ kthread_stop */
343 set_current_state(TASK_INTERRUPTIBLE);
345 if (kthread_should_stop()) {
346 __set_current_state(TASK_RUNNING);
350 node = llist_del_all(&dev->work_list);
354 node = llist_reverse_order(node);
355 /* make sure flag is seen after deletion */
357 llist_for_each_entry_safe(work, work_next, node, node) {
358 clear_bit(VHOST_WORK_QUEUED, &work->flags);
359 __set_current_state(TASK_RUNNING);
370 static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq)
380 /* Helper to allocate iovec buffers for all vqs. */
381 static long vhost_dev_alloc_iovecs(struct vhost_dev *dev)
383 struct vhost_virtqueue *vq;
386 for (i = 0; i < dev->nvqs; ++i) {
388 vq->indirect = kmalloc(sizeof *vq->indirect * UIO_MAXIOV,
390 vq->log = kmalloc(sizeof *vq->log * UIO_MAXIOV, GFP_KERNEL);
391 vq->heads = kmalloc(sizeof *vq->heads * UIO_MAXIOV, GFP_KERNEL);
392 if (!vq->indirect || !vq->log || !vq->heads)
399 vhost_vq_free_iovecs(dev->vqs[i]);
403 static void vhost_dev_free_iovecs(struct vhost_dev *dev)
407 for (i = 0; i < dev->nvqs; ++i)
408 vhost_vq_free_iovecs(dev->vqs[i]);
411 void vhost_dev_init(struct vhost_dev *dev,
412 struct vhost_virtqueue **vqs, int nvqs)
414 struct vhost_virtqueue *vq;
419 mutex_init(&dev->mutex);
425 init_llist_head(&dev->work_list);
426 init_waitqueue_head(&dev->wait);
427 INIT_LIST_HEAD(&dev->read_list);
428 INIT_LIST_HEAD(&dev->pending_list);
429 spin_lock_init(&dev->iotlb_lock);
432 for (i = 0; i < dev->nvqs; ++i) {
438 mutex_init(&vq->mutex);
439 vhost_vq_reset(dev, vq);
441 vhost_poll_init(&vq->poll, vq->handle_kick,
445 EXPORT_SYMBOL_GPL(vhost_dev_init);
447 /* Caller should have device mutex */
448 long vhost_dev_check_owner(struct vhost_dev *dev)
450 /* Are you the owner? If not, I don't think you mean to do that */
451 return dev->mm == current->mm ? 0 : -EPERM;
453 EXPORT_SYMBOL_GPL(vhost_dev_check_owner);
455 struct vhost_attach_cgroups_struct {
456 struct vhost_work work;
457 struct task_struct *owner;
461 static void vhost_attach_cgroups_work(struct vhost_work *work)
463 struct vhost_attach_cgroups_struct *s;
465 s = container_of(work, struct vhost_attach_cgroups_struct, work);
466 s->ret = cgroup_attach_task_all(s->owner, current);
469 static int vhost_attach_cgroups(struct vhost_dev *dev)
471 struct vhost_attach_cgroups_struct attach;
473 attach.owner = current;
474 vhost_work_init(&attach.work, vhost_attach_cgroups_work);
475 vhost_work_queue(dev, &attach.work);
476 vhost_work_flush(dev, &attach.work);
480 /* Caller should have device mutex */
481 bool vhost_dev_has_owner(struct vhost_dev *dev)
485 EXPORT_SYMBOL_GPL(vhost_dev_has_owner);
487 /* Caller should have device mutex */
488 long vhost_dev_set_owner(struct vhost_dev *dev)
490 struct task_struct *worker;
493 /* Is there an owner already? */
494 if (vhost_dev_has_owner(dev)) {
499 /* No owner, become one */
500 dev->mm = get_task_mm(current);
501 worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid);
502 if (IS_ERR(worker)) {
503 err = PTR_ERR(worker);
507 dev->worker = worker;
508 wake_up_process(worker); /* avoid contributing to loadavg */
510 err = vhost_attach_cgroups(dev);
514 err = vhost_dev_alloc_iovecs(dev);
520 kthread_stop(worker);
529 EXPORT_SYMBOL_GPL(vhost_dev_set_owner);
531 struct vhost_umem *vhost_dev_reset_owner_prepare(void)
533 return kvzalloc(sizeof(struct vhost_umem), GFP_KERNEL);
535 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner_prepare);
537 /* Caller should have device mutex */
538 void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_umem *umem)
542 vhost_dev_cleanup(dev);
544 /* Restore memory to default empty mapping. */
545 INIT_LIST_HEAD(&umem->umem_list);
547 /* We don't need VQ locks below since vhost_dev_cleanup makes sure
548 * VQs aren't running.
550 for (i = 0; i < dev->nvqs; ++i)
551 dev->vqs[i]->umem = umem;
553 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner);
555 void vhost_dev_stop(struct vhost_dev *dev)
559 for (i = 0; i < dev->nvqs; ++i) {
560 if (dev->vqs[i]->kick && dev->vqs[i]->handle_kick) {
561 vhost_poll_stop(&dev->vqs[i]->poll);
562 vhost_poll_flush(&dev->vqs[i]->poll);
566 EXPORT_SYMBOL_GPL(vhost_dev_stop);
568 static void vhost_umem_free(struct vhost_umem *umem,
569 struct vhost_umem_node *node)
571 vhost_umem_interval_tree_remove(node, &umem->umem_tree);
572 list_del(&node->link);
577 static void vhost_umem_clean(struct vhost_umem *umem)
579 struct vhost_umem_node *node, *tmp;
584 list_for_each_entry_safe(node, tmp, &umem->umem_list, link)
585 vhost_umem_free(umem, node);
590 static void vhost_clear_msg(struct vhost_dev *dev)
592 struct vhost_msg_node *node, *n;
594 spin_lock(&dev->iotlb_lock);
596 list_for_each_entry_safe(node, n, &dev->read_list, node) {
597 list_del(&node->node);
601 list_for_each_entry_safe(node, n, &dev->pending_list, node) {
602 list_del(&node->node);
606 spin_unlock(&dev->iotlb_lock);
609 void vhost_dev_cleanup(struct vhost_dev *dev)
613 for (i = 0; i < dev->nvqs; ++i) {
614 if (dev->vqs[i]->error_ctx)
615 eventfd_ctx_put(dev->vqs[i]->error_ctx);
616 if (dev->vqs[i]->kick)
617 fput(dev->vqs[i]->kick);
618 if (dev->vqs[i]->call_ctx)
619 eventfd_ctx_put(dev->vqs[i]->call_ctx);
620 vhost_vq_reset(dev, dev->vqs[i]);
622 vhost_dev_free_iovecs(dev);
624 eventfd_ctx_put(dev->log_ctx);
626 /* No one will access memory at this point */
627 vhost_umem_clean(dev->umem);
629 vhost_umem_clean(dev->iotlb);
631 vhost_clear_msg(dev);
632 wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
633 WARN_ON(!llist_empty(&dev->work_list));
635 kthread_stop(dev->worker);
642 EXPORT_SYMBOL_GPL(vhost_dev_cleanup);
644 static bool log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
646 u64 a = addr / VHOST_PAGE_SIZE / 8;
648 /* Make sure 64 bit math will not overflow. */
649 if (a > ULONG_MAX - (unsigned long)log_base ||
650 a + (unsigned long)log_base > ULONG_MAX)
653 return access_ok(VERIFY_WRITE, log_base + a,
654 (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8);
657 static bool vhost_overflow(u64 uaddr, u64 size)
659 /* Make sure 64 bit math will not overflow. */
660 return uaddr > ULONG_MAX || size > ULONG_MAX || uaddr > ULONG_MAX - size;
663 /* Caller should have vq mutex and device mutex. */
664 static bool vq_memory_access_ok(void __user *log_base, struct vhost_umem *umem,
667 struct vhost_umem_node *node;
672 list_for_each_entry(node, &umem->umem_list, link) {
673 unsigned long a = node->userspace_addr;
675 if (vhost_overflow(node->userspace_addr, node->size))
679 if (!access_ok(VERIFY_WRITE, (void __user *)a,
682 else if (log_all && !log_access_ok(log_base,
690 static inline void __user *vhost_vq_meta_fetch(struct vhost_virtqueue *vq,
691 u64 addr, unsigned int size,
694 const struct vhost_umem_node *node = vq->meta_iotlb[type];
699 return (void *)(uintptr_t)(node->userspace_addr + addr - node->start);
702 /* Can we switch to this memory table? */
703 /* Caller should have device mutex but not vq mutex */
704 static bool memory_access_ok(struct vhost_dev *d, struct vhost_umem *umem,
709 for (i = 0; i < d->nvqs; ++i) {
713 mutex_lock(&d->vqs[i]->mutex);
714 log = log_all || vhost_has_feature(d->vqs[i], VHOST_F_LOG_ALL);
715 /* If ring is inactive, will check when it's enabled. */
716 if (d->vqs[i]->private_data)
717 ok = vq_memory_access_ok(d->vqs[i]->log_base,
721 mutex_unlock(&d->vqs[i]->mutex);
728 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
729 struct iovec iov[], int iov_size, int access);
731 static int vhost_copy_to_user(struct vhost_virtqueue *vq, void __user *to,
732 const void *from, unsigned size)
737 return __copy_to_user(to, from, size);
739 /* This function should be called after iotlb
740 * prefetch, which means we're sure that all vq
741 * could be access through iotlb. So -EAGAIN should
742 * not happen in this case.
745 void __user *uaddr = vhost_vq_meta_fetch(vq,
746 (u64)(uintptr_t)to, size,
750 return __copy_to_user(uaddr, from, size);
752 ret = translate_desc(vq, (u64)(uintptr_t)to, size, vq->iotlb_iov,
753 ARRAY_SIZE(vq->iotlb_iov),
757 iov_iter_init(&t, WRITE, vq->iotlb_iov, ret, size);
758 ret = copy_to_iter(from, size, &t);
766 static int vhost_copy_from_user(struct vhost_virtqueue *vq, void *to,
767 void __user *from, unsigned size)
772 return __copy_from_user(to, from, size);
774 /* This function should be called after iotlb
775 * prefetch, which means we're sure that vq
776 * could be access through iotlb. So -EAGAIN should
777 * not happen in this case.
779 void __user *uaddr = vhost_vq_meta_fetch(vq,
780 (u64)(uintptr_t)from, size,
785 return __copy_from_user(to, uaddr, size);
787 ret = translate_desc(vq, (u64)(uintptr_t)from, size, vq->iotlb_iov,
788 ARRAY_SIZE(vq->iotlb_iov),
791 vq_err(vq, "IOTLB translation failure: uaddr "
792 "%p size 0x%llx\n", from,
793 (unsigned long long) size);
796 iov_iter_init(&f, READ, vq->iotlb_iov, ret, size);
797 ret = copy_from_iter(to, size, &f);
806 static void __user *__vhost_get_user_slow(struct vhost_virtqueue *vq,
807 void __user *addr, unsigned int size,
812 ret = translate_desc(vq, (u64)(uintptr_t)addr, size, vq->iotlb_iov,
813 ARRAY_SIZE(vq->iotlb_iov),
816 vq_err(vq, "IOTLB translation failure: uaddr "
817 "%p size 0x%llx\n", addr,
818 (unsigned long long) size);
822 if (ret != 1 || vq->iotlb_iov[0].iov_len != size) {
823 vq_err(vq, "Non atomic userspace memory access: uaddr "
824 "%p size 0x%llx\n", addr,
825 (unsigned long long) size);
829 return vq->iotlb_iov[0].iov_base;
832 /* This function should be called after iotlb
833 * prefetch, which means we're sure that vq
834 * could be access through iotlb. So -EAGAIN should
835 * not happen in this case.
837 static inline void __user *__vhost_get_user(struct vhost_virtqueue *vq,
838 void *addr, unsigned int size,
841 void __user *uaddr = vhost_vq_meta_fetch(vq,
842 (u64)(uintptr_t)addr, size, type);
846 return __vhost_get_user_slow(vq, addr, size, type);
849 #define vhost_put_user(vq, x, ptr) \
853 ret = __put_user(x, ptr); \
855 __typeof__(ptr) to = \
856 (__typeof__(ptr)) __vhost_get_user(vq, ptr, \
857 sizeof(*ptr), VHOST_ADDR_USED); \
859 ret = __put_user(x, to); \
866 #define vhost_get_user(vq, x, ptr, type) \
870 ret = __get_user(x, ptr); \
872 __typeof__(ptr) from = \
873 (__typeof__(ptr)) __vhost_get_user(vq, ptr, \
877 ret = __get_user(x, from); \
884 #define vhost_get_avail(vq, x, ptr) \
885 vhost_get_user(vq, x, ptr, VHOST_ADDR_AVAIL)
887 #define vhost_get_used(vq, x, ptr) \
888 vhost_get_user(vq, x, ptr, VHOST_ADDR_USED)
890 static void vhost_dev_lock_vqs(struct vhost_dev *d)
893 for (i = 0; i < d->nvqs; ++i)
894 mutex_lock_nested(&d->vqs[i]->mutex, i);
897 static void vhost_dev_unlock_vqs(struct vhost_dev *d)
900 for (i = 0; i < d->nvqs; ++i)
901 mutex_unlock(&d->vqs[i]->mutex);
904 static int vhost_new_umem_range(struct vhost_umem *umem,
905 u64 start, u64 size, u64 end,
906 u64 userspace_addr, int perm)
908 struct vhost_umem_node *tmp, *node = kmalloc(sizeof(*node), GFP_ATOMIC);
913 if (umem->numem == max_iotlb_entries) {
914 tmp = list_first_entry(&umem->umem_list, typeof(*tmp), link);
915 vhost_umem_free(umem, tmp);
921 node->userspace_addr = userspace_addr;
923 INIT_LIST_HEAD(&node->link);
924 list_add_tail(&node->link, &umem->umem_list);
925 vhost_umem_interval_tree_insert(node, &umem->umem_tree);
931 static void vhost_del_umem_range(struct vhost_umem *umem,
934 struct vhost_umem_node *node;
936 while ((node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
938 vhost_umem_free(umem, node);
941 static void vhost_iotlb_notify_vq(struct vhost_dev *d,
942 struct vhost_iotlb_msg *msg)
944 struct vhost_msg_node *node, *n;
946 spin_lock(&d->iotlb_lock);
948 list_for_each_entry_safe(node, n, &d->pending_list, node) {
949 struct vhost_iotlb_msg *vq_msg = &node->msg.iotlb;
950 if (msg->iova <= vq_msg->iova &&
951 msg->iova + msg->size - 1 > vq_msg->iova &&
952 vq_msg->type == VHOST_IOTLB_MISS) {
953 vhost_poll_queue(&node->vq->poll);
954 list_del(&node->node);
959 spin_unlock(&d->iotlb_lock);
962 static bool umem_access_ok(u64 uaddr, u64 size, int access)
964 unsigned long a = uaddr;
966 /* Make sure 64 bit math will not overflow. */
967 if (vhost_overflow(uaddr, size))
970 if ((access & VHOST_ACCESS_RO) &&
971 !access_ok(VERIFY_READ, (void __user *)a, size))
973 if ((access & VHOST_ACCESS_WO) &&
974 !access_ok(VERIFY_WRITE, (void __user *)a, size))
979 static int vhost_process_iotlb_msg(struct vhost_dev *dev,
980 struct vhost_iotlb_msg *msg)
984 vhost_dev_lock_vqs(dev);
986 case VHOST_IOTLB_UPDATE:
991 if (!umem_access_ok(msg->uaddr, msg->size, msg->perm)) {
995 vhost_vq_meta_reset(dev);
996 if (vhost_new_umem_range(dev->iotlb, msg->iova, msg->size,
997 msg->iova + msg->size - 1,
998 msg->uaddr, msg->perm)) {
1002 vhost_iotlb_notify_vq(dev, msg);
1004 case VHOST_IOTLB_INVALIDATE:
1009 vhost_vq_meta_reset(dev);
1010 vhost_del_umem_range(dev->iotlb, msg->iova,
1011 msg->iova + msg->size - 1);
1018 vhost_dev_unlock_vqs(dev);
1021 ssize_t vhost_chr_write_iter(struct vhost_dev *dev,
1022 struct iov_iter *from)
1024 struct vhost_msg_node node;
1025 unsigned size = sizeof(struct vhost_msg);
1029 if (iov_iter_count(from) < size)
1031 ret = copy_from_iter(&node.msg, size, from);
1035 switch (node.msg.type) {
1036 case VHOST_IOTLB_MSG:
1037 err = vhost_process_iotlb_msg(dev, &node.msg.iotlb);
1049 EXPORT_SYMBOL(vhost_chr_write_iter);
1051 __poll_t vhost_chr_poll(struct file *file, struct vhost_dev *dev,
1056 poll_wait(file, &dev->wait, wait);
1058 if (!list_empty(&dev->read_list))
1059 mask |= EPOLLIN | EPOLLRDNORM;
1063 EXPORT_SYMBOL(vhost_chr_poll);
1065 ssize_t vhost_chr_read_iter(struct vhost_dev *dev, struct iov_iter *to,
1069 struct vhost_msg_node *node;
1071 unsigned size = sizeof(struct vhost_msg);
1073 if (iov_iter_count(to) < size)
1078 prepare_to_wait(&dev->wait, &wait,
1079 TASK_INTERRUPTIBLE);
1081 node = vhost_dequeue_msg(dev, &dev->read_list);
1088 if (signal_pending(current)) {
1101 finish_wait(&dev->wait, &wait);
1104 ret = copy_to_iter(&node->msg, size, to);
1106 if (ret != size || node->msg.type != VHOST_IOTLB_MISS) {
1111 vhost_enqueue_msg(dev, &dev->pending_list, node);
1116 EXPORT_SYMBOL_GPL(vhost_chr_read_iter);
1118 static int vhost_iotlb_miss(struct vhost_virtqueue *vq, u64 iova, int access)
1120 struct vhost_dev *dev = vq->dev;
1121 struct vhost_msg_node *node;
1122 struct vhost_iotlb_msg *msg;
1124 node = vhost_new_msg(vq, VHOST_IOTLB_MISS);
1128 msg = &node->msg.iotlb;
1129 msg->type = VHOST_IOTLB_MISS;
1133 vhost_enqueue_msg(dev, &dev->read_list, node);
1138 static bool vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
1139 struct vring_desc __user *desc,
1140 struct vring_avail __user *avail,
1141 struct vring_used __user *used)
1144 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
1146 return access_ok(VERIFY_READ, desc, num * sizeof *desc) &&
1147 access_ok(VERIFY_READ, avail,
1148 sizeof *avail + num * sizeof *avail->ring + s) &&
1149 access_ok(VERIFY_WRITE, used,
1150 sizeof *used + num * sizeof *used->ring + s);
1153 static void vhost_vq_meta_update(struct vhost_virtqueue *vq,
1154 const struct vhost_umem_node *node,
1157 int access = (type == VHOST_ADDR_USED) ?
1158 VHOST_ACCESS_WO : VHOST_ACCESS_RO;
1160 if (likely(node->perm & access))
1161 vq->meta_iotlb[type] = node;
1164 static bool iotlb_access_ok(struct vhost_virtqueue *vq,
1165 int access, u64 addr, u64 len, int type)
1167 const struct vhost_umem_node *node;
1168 struct vhost_umem *umem = vq->iotlb;
1169 u64 s = 0, size, orig_addr = addr, last = addr + len - 1;
1171 if (vhost_vq_meta_fetch(vq, addr, len, type))
1175 node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
1178 if (node == NULL || node->start > addr) {
1179 vhost_iotlb_miss(vq, addr, access);
1181 } else if (!(node->perm & access)) {
1182 /* Report the possible access violation by
1183 * request another translation from userspace.
1188 size = node->size - addr + node->start;
1190 if (orig_addr == addr && size >= len)
1191 vhost_vq_meta_update(vq, node, type);
1200 int vq_iotlb_prefetch(struct vhost_virtqueue *vq)
1202 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
1203 unsigned int num = vq->num;
1208 return iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->desc,
1209 num * sizeof(*vq->desc), VHOST_ADDR_DESC) &&
1210 iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->avail,
1212 num * sizeof(*vq->avail->ring) + s,
1213 VHOST_ADDR_AVAIL) &&
1214 iotlb_access_ok(vq, VHOST_ACCESS_WO, (u64)(uintptr_t)vq->used,
1216 num * sizeof(*vq->used->ring) + s,
1219 EXPORT_SYMBOL_GPL(vq_iotlb_prefetch);
1221 /* Can we log writes? */
1222 /* Caller should have device mutex but not vq mutex */
1223 bool vhost_log_access_ok(struct vhost_dev *dev)
1225 return memory_access_ok(dev, dev->umem, 1);
1227 EXPORT_SYMBOL_GPL(vhost_log_access_ok);
1229 /* Verify access for write logging. */
1230 /* Caller should have vq mutex and device mutex */
1231 static bool vq_log_access_ok(struct vhost_virtqueue *vq,
1232 void __user *log_base)
1234 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
1236 return vq_memory_access_ok(log_base, vq->umem,
1237 vhost_has_feature(vq, VHOST_F_LOG_ALL)) &&
1238 (!vq->log_used || log_access_ok(log_base, vq->log_addr,
1240 vq->num * sizeof *vq->used->ring + s));
1243 /* Can we start vq? */
1244 /* Caller should have vq mutex and device mutex */
1245 bool vhost_vq_access_ok(struct vhost_virtqueue *vq)
1247 if (!vq_log_access_ok(vq, vq->log_base))
1250 /* Access validation occurs at prefetch time with IOTLB */
1254 return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used);
1256 EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
1258 static struct vhost_umem *vhost_umem_alloc(void)
1260 struct vhost_umem *umem = kvzalloc(sizeof(*umem), GFP_KERNEL);
1265 umem->umem_tree = RB_ROOT_CACHED;
1267 INIT_LIST_HEAD(&umem->umem_list);
1272 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
1274 struct vhost_memory mem, *newmem;
1275 struct vhost_memory_region *region;
1276 struct vhost_umem *newumem, *oldumem;
1277 unsigned long size = offsetof(struct vhost_memory, regions);
1280 if (copy_from_user(&mem, m, size))
1284 if (mem.nregions > max_mem_regions)
1286 newmem = kvzalloc(size + mem.nregions * sizeof(*m->regions), GFP_KERNEL);
1290 memcpy(newmem, &mem, size);
1291 if (copy_from_user(newmem->regions, m->regions,
1292 mem.nregions * sizeof *m->regions)) {
1297 newumem = vhost_umem_alloc();
1303 for (region = newmem->regions;
1304 region < newmem->regions + mem.nregions;
1306 if (vhost_new_umem_range(newumem,
1307 region->guest_phys_addr,
1308 region->memory_size,
1309 region->guest_phys_addr +
1310 region->memory_size - 1,
1311 region->userspace_addr,
1316 if (!memory_access_ok(d, newumem, 0))
1322 /* All memory accesses are done under some VQ mutex. */
1323 for (i = 0; i < d->nvqs; ++i) {
1324 mutex_lock(&d->vqs[i]->mutex);
1325 d->vqs[i]->umem = newumem;
1326 mutex_unlock(&d->vqs[i]->mutex);
1330 vhost_umem_clean(oldumem);
1334 vhost_umem_clean(newumem);
1339 long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
1341 struct file *eventfp, *filep = NULL;
1342 bool pollstart = false, pollstop = false;
1343 struct eventfd_ctx *ctx = NULL;
1344 u32 __user *idxp = argp;
1345 struct vhost_virtqueue *vq;
1346 struct vhost_vring_state s;
1347 struct vhost_vring_file f;
1348 struct vhost_vring_addr a;
1352 r = get_user(idx, idxp);
1360 mutex_lock(&vq->mutex);
1363 case VHOST_SET_VRING_NUM:
1364 /* Resizing ring with an active backend?
1365 * You don't want to do that. */
1366 if (vq->private_data) {
1370 if (copy_from_user(&s, argp, sizeof s)) {
1374 if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) {
1380 case VHOST_SET_VRING_BASE:
1381 /* Moving base with an active backend?
1382 * You don't want to do that. */
1383 if (vq->private_data) {
1387 if (copy_from_user(&s, argp, sizeof s)) {
1391 if (s.num > 0xffff) {
1395 vq->last_avail_idx = s.num;
1396 /* Forget the cached index value. */
1397 vq->avail_idx = vq->last_avail_idx;
1399 case VHOST_GET_VRING_BASE:
1401 s.num = vq->last_avail_idx;
1402 if (copy_to_user(argp, &s, sizeof s))
1405 case VHOST_SET_VRING_ADDR:
1406 if (copy_from_user(&a, argp, sizeof a)) {
1410 if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) {
1414 /* For 32bit, verify that the top 32bits of the user
1415 data are set to zero. */
1416 if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr ||
1417 (u64)(unsigned long)a.used_user_addr != a.used_user_addr ||
1418 (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) {
1423 /* Make sure it's safe to cast pointers to vring types. */
1424 BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE);
1425 BUILD_BUG_ON(__alignof__ *vq->used > VRING_USED_ALIGN_SIZE);
1426 if ((a.avail_user_addr & (VRING_AVAIL_ALIGN_SIZE - 1)) ||
1427 (a.used_user_addr & (VRING_USED_ALIGN_SIZE - 1)) ||
1428 (a.log_guest_addr & (VRING_USED_ALIGN_SIZE - 1))) {
1433 /* We only verify access here if backend is configured.
1434 * If it is not, we don't as size might not have been setup.
1435 * We will verify when backend is configured. */
1436 if (vq->private_data) {
1437 if (!vq_access_ok(vq, vq->num,
1438 (void __user *)(unsigned long)a.desc_user_addr,
1439 (void __user *)(unsigned long)a.avail_user_addr,
1440 (void __user *)(unsigned long)a.used_user_addr)) {
1445 /* Also validate log access for used ring if enabled. */
1446 if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) &&
1447 !log_access_ok(vq->log_base, a.log_guest_addr,
1449 vq->num * sizeof *vq->used->ring)) {
1455 vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
1456 vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
1457 vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
1458 vq->log_addr = a.log_guest_addr;
1459 vq->used = (void __user *)(unsigned long)a.used_user_addr;
1461 case VHOST_SET_VRING_KICK:
1462 if (copy_from_user(&f, argp, sizeof f)) {
1466 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
1467 if (IS_ERR(eventfp)) {
1468 r = PTR_ERR(eventfp);
1471 if (eventfp != vq->kick) {
1472 pollstop = (filep = vq->kick) != NULL;
1473 pollstart = (vq->kick = eventfp) != NULL;
1477 case VHOST_SET_VRING_CALL:
1478 if (copy_from_user(&f, argp, sizeof f)) {
1482 ctx = f.fd == -1 ? NULL : eventfd_ctx_fdget(f.fd);
1487 swap(ctx, vq->call_ctx);
1489 case VHOST_SET_VRING_ERR:
1490 if (copy_from_user(&f, argp, sizeof f)) {
1494 ctx = f.fd == -1 ? NULL : eventfd_ctx_fdget(f.fd);
1499 swap(ctx, vq->error_ctx);
1501 case VHOST_SET_VRING_ENDIAN:
1502 r = vhost_set_vring_endian(vq, argp);
1504 case VHOST_GET_VRING_ENDIAN:
1505 r = vhost_get_vring_endian(vq, idx, argp);
1507 case VHOST_SET_VRING_BUSYLOOP_TIMEOUT:
1508 if (copy_from_user(&s, argp, sizeof(s))) {
1512 vq->busyloop_timeout = s.num;
1514 case VHOST_GET_VRING_BUSYLOOP_TIMEOUT:
1516 s.num = vq->busyloop_timeout;
1517 if (copy_to_user(argp, &s, sizeof(s)))
1524 if (pollstop && vq->handle_kick)
1525 vhost_poll_stop(&vq->poll);
1527 if (!IS_ERR_OR_NULL(ctx))
1528 eventfd_ctx_put(ctx);
1532 if (pollstart && vq->handle_kick)
1533 r = vhost_poll_start(&vq->poll, vq->kick);
1535 mutex_unlock(&vq->mutex);
1537 if (pollstop && vq->handle_kick)
1538 vhost_poll_flush(&vq->poll);
1541 EXPORT_SYMBOL_GPL(vhost_vring_ioctl);
1543 int vhost_init_device_iotlb(struct vhost_dev *d, bool enabled)
1545 struct vhost_umem *niotlb, *oiotlb;
1548 niotlb = vhost_umem_alloc();
1555 for (i = 0; i < d->nvqs; ++i) {
1556 mutex_lock(&d->vqs[i]->mutex);
1557 d->vqs[i]->iotlb = niotlb;
1558 mutex_unlock(&d->vqs[i]->mutex);
1561 vhost_umem_clean(oiotlb);
1565 EXPORT_SYMBOL_GPL(vhost_init_device_iotlb);
1567 /* Caller must have device mutex */
1568 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
1570 struct eventfd_ctx *ctx;
1575 /* If you are not the owner, you can become one */
1576 if (ioctl == VHOST_SET_OWNER) {
1577 r = vhost_dev_set_owner(d);
1581 /* You must be the owner to do anything else */
1582 r = vhost_dev_check_owner(d);
1587 case VHOST_SET_MEM_TABLE:
1588 r = vhost_set_memory(d, argp);
1590 case VHOST_SET_LOG_BASE:
1591 if (copy_from_user(&p, argp, sizeof p)) {
1595 if ((u64)(unsigned long)p != p) {
1599 for (i = 0; i < d->nvqs; ++i) {
1600 struct vhost_virtqueue *vq;
1601 void __user *base = (void __user *)(unsigned long)p;
1603 mutex_lock(&vq->mutex);
1604 /* If ring is inactive, will check when it's enabled. */
1605 if (vq->private_data && !vq_log_access_ok(vq, base))
1608 vq->log_base = base;
1609 mutex_unlock(&vq->mutex);
1612 case VHOST_SET_LOG_FD:
1613 r = get_user(fd, (int __user *)argp);
1616 ctx = fd == -1 ? NULL : eventfd_ctx_fdget(fd);
1621 swap(ctx, d->log_ctx);
1622 for (i = 0; i < d->nvqs; ++i) {
1623 mutex_lock(&d->vqs[i]->mutex);
1624 d->vqs[i]->log_ctx = d->log_ctx;
1625 mutex_unlock(&d->vqs[i]->mutex);
1628 eventfd_ctx_put(ctx);
1637 EXPORT_SYMBOL_GPL(vhost_dev_ioctl);
1639 /* TODO: This is really inefficient. We need something like get_user()
1640 * (instruction directly accesses the data, with an exception table entry
1641 * returning -EFAULT). See Documentation/x86/exception-tables.txt.
1643 static int set_bit_to_user(int nr, void __user *addr)
1645 unsigned long log = (unsigned long)addr;
1648 int bit = nr + (log % PAGE_SIZE) * 8;
1651 r = get_user_pages_fast(log, 1, 1, &page);
1655 base = kmap_atomic(page);
1657 kunmap_atomic(base);
1658 set_page_dirty_lock(page);
1663 static int log_write(void __user *log_base,
1664 u64 write_address, u64 write_length)
1666 u64 write_page = write_address / VHOST_PAGE_SIZE;
1671 write_length += write_address % VHOST_PAGE_SIZE;
1673 u64 base = (u64)(unsigned long)log_base;
1674 u64 log = base + write_page / 8;
1675 int bit = write_page % 8;
1676 if ((u64)(unsigned long)log != log)
1678 r = set_bit_to_user(bit, (void __user *)(unsigned long)log);
1681 if (write_length <= VHOST_PAGE_SIZE)
1683 write_length -= VHOST_PAGE_SIZE;
1689 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
1690 unsigned int log_num, u64 len)
1694 /* Make sure data written is seen before log. */
1696 for (i = 0; i < log_num; ++i) {
1697 u64 l = min(log[i].len, len);
1698 r = log_write(vq->log_base, log[i].addr, l);
1704 eventfd_signal(vq->log_ctx, 1);
1708 /* Length written exceeds what we have stored. This is a bug. */
1712 EXPORT_SYMBOL_GPL(vhost_log_write);
1714 static int vhost_update_used_flags(struct vhost_virtqueue *vq)
1717 if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->used_flags),
1718 &vq->used->flags) < 0)
1720 if (unlikely(vq->log_used)) {
1721 /* Make sure the flag is seen before log. */
1723 /* Log used flag write. */
1724 used = &vq->used->flags;
1725 log_write(vq->log_base, vq->log_addr +
1726 (used - (void __user *)vq->used),
1727 sizeof vq->used->flags);
1729 eventfd_signal(vq->log_ctx, 1);
1734 static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event)
1736 if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->avail_idx),
1737 vhost_avail_event(vq)))
1739 if (unlikely(vq->log_used)) {
1741 /* Make sure the event is seen before log. */
1743 /* Log avail event write */
1744 used = vhost_avail_event(vq);
1745 log_write(vq->log_base, vq->log_addr +
1746 (used - (void __user *)vq->used),
1747 sizeof *vhost_avail_event(vq));
1749 eventfd_signal(vq->log_ctx, 1);
1754 int vhost_vq_init_access(struct vhost_virtqueue *vq)
1756 __virtio16 last_used_idx;
1758 bool is_le = vq->is_le;
1760 if (!vq->private_data)
1763 vhost_init_is_le(vq);
1765 r = vhost_update_used_flags(vq);
1768 vq->signalled_used_valid = false;
1770 !access_ok(VERIFY_READ, &vq->used->idx, sizeof vq->used->idx)) {
1774 r = vhost_get_used(vq, last_used_idx, &vq->used->idx);
1776 vq_err(vq, "Can't access used idx at %p\n",
1780 vq->last_used_idx = vhost16_to_cpu(vq, last_used_idx);
1787 EXPORT_SYMBOL_GPL(vhost_vq_init_access);
1789 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
1790 struct iovec iov[], int iov_size, int access)
1792 const struct vhost_umem_node *node;
1793 struct vhost_dev *dev = vq->dev;
1794 struct vhost_umem *umem = dev->iotlb ? dev->iotlb : dev->umem;
1799 while ((u64)len > s) {
1801 if (unlikely(ret >= iov_size)) {
1806 node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
1807 addr, addr + len - 1);
1808 if (node == NULL || node->start > addr) {
1809 if (umem != dev->iotlb) {
1815 } else if (!(node->perm & access)) {
1821 size = node->size - addr + node->start;
1822 _iov->iov_len = min((u64)len - s, size);
1823 _iov->iov_base = (void __user *)(unsigned long)
1824 (node->userspace_addr + addr - node->start);
1831 vhost_iotlb_miss(vq, addr, access);
1835 /* Each buffer in the virtqueues is actually a chain of descriptors. This
1836 * function returns the next descriptor in the chain,
1837 * or -1U if we're at the end. */
1838 static unsigned next_desc(struct vhost_virtqueue *vq, struct vring_desc *desc)
1842 /* If this descriptor says it doesn't chain, we're done. */
1843 if (!(desc->flags & cpu_to_vhost16(vq, VRING_DESC_F_NEXT)))
1846 /* Check they're not leading us off end of descriptors. */
1847 next = vhost16_to_cpu(vq, READ_ONCE(desc->next));
1851 static int get_indirect(struct vhost_virtqueue *vq,
1852 struct iovec iov[], unsigned int iov_size,
1853 unsigned int *out_num, unsigned int *in_num,
1854 struct vhost_log *log, unsigned int *log_num,
1855 struct vring_desc *indirect)
1857 struct vring_desc desc;
1858 unsigned int i = 0, count, found = 0;
1859 u32 len = vhost32_to_cpu(vq, indirect->len);
1860 struct iov_iter from;
1864 if (unlikely(len % sizeof desc)) {
1865 vq_err(vq, "Invalid length in indirect descriptor: "
1866 "len 0x%llx not multiple of 0x%zx\n",
1867 (unsigned long long)len,
1872 ret = translate_desc(vq, vhost64_to_cpu(vq, indirect->addr), len, vq->indirect,
1873 UIO_MAXIOV, VHOST_ACCESS_RO);
1874 if (unlikely(ret < 0)) {
1876 vq_err(vq, "Translation failure %d in indirect.\n", ret);
1879 iov_iter_init(&from, READ, vq->indirect, ret, len);
1881 /* We will use the result as an address to read from, so most
1882 * architectures only need a compiler barrier here. */
1883 read_barrier_depends();
1885 count = len / sizeof desc;
1886 /* Buffers are chained via a 16 bit next field, so
1887 * we can have at most 2^16 of these. */
1888 if (unlikely(count > USHRT_MAX + 1)) {
1889 vq_err(vq, "Indirect buffer length too big: %d\n",
1895 unsigned iov_count = *in_num + *out_num;
1896 if (unlikely(++found > count)) {
1897 vq_err(vq, "Loop detected: last one at %u "
1898 "indirect size %u\n",
1902 if (unlikely(!copy_from_iter_full(&desc, sizeof(desc), &from))) {
1903 vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n",
1904 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
1907 if (unlikely(desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT))) {
1908 vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n",
1909 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
1913 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
1914 access = VHOST_ACCESS_WO;
1916 access = VHOST_ACCESS_RO;
1918 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
1919 vhost32_to_cpu(vq, desc.len), iov + iov_count,
1920 iov_size - iov_count, access);
1921 if (unlikely(ret < 0)) {
1923 vq_err(vq, "Translation failure %d indirect idx %d\n",
1927 /* If this is an input descriptor, increment that count. */
1928 if (access == VHOST_ACCESS_WO) {
1930 if (unlikely(log)) {
1931 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
1932 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
1936 /* If it's an output descriptor, they're all supposed
1937 * to come before any input descriptors. */
1938 if (unlikely(*in_num)) {
1939 vq_err(vq, "Indirect descriptor "
1940 "has out after in: idx %d\n", i);
1945 } while ((i = next_desc(vq, &desc)) != -1);
1949 /* This looks in the virtqueue and for the first available buffer, and converts
1950 * it to an iovec for convenient access. Since descriptors consist of some
1951 * number of output then some number of input descriptors, it's actually two
1952 * iovecs, but we pack them into one and note how many of each there were.
1954 * This function returns the descriptor number found, or vq->num (which is
1955 * never a valid descriptor number) if none was found. A negative code is
1956 * returned on error. */
1957 int vhost_get_vq_desc(struct vhost_virtqueue *vq,
1958 struct iovec iov[], unsigned int iov_size,
1959 unsigned int *out_num, unsigned int *in_num,
1960 struct vhost_log *log, unsigned int *log_num)
1962 struct vring_desc desc;
1963 unsigned int i, head, found = 0;
1965 __virtio16 avail_idx;
1966 __virtio16 ring_head;
1969 /* Check it isn't doing very strange things with descriptor numbers. */
1970 last_avail_idx = vq->last_avail_idx;
1972 if (vq->avail_idx == vq->last_avail_idx) {
1973 if (unlikely(vhost_get_avail(vq, avail_idx, &vq->avail->idx))) {
1974 vq_err(vq, "Failed to access avail idx at %p\n",
1978 vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
1980 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
1981 vq_err(vq, "Guest moved used index from %u to %u",
1982 last_avail_idx, vq->avail_idx);
1986 /* If there's nothing new since last we looked, return
1989 if (vq->avail_idx == last_avail_idx)
1992 /* Only get avail ring entries after they have been
1998 /* Grab the next descriptor number they're advertising, and increment
1999 * the index we've seen. */
2000 if (unlikely(vhost_get_avail(vq, ring_head,
2001 &vq->avail->ring[last_avail_idx & (vq->num - 1)]))) {
2002 vq_err(vq, "Failed to read head: idx %d address %p\n",
2004 &vq->avail->ring[last_avail_idx % vq->num]);
2008 head = vhost16_to_cpu(vq, ring_head);
2010 /* If their number is silly, that's an error. */
2011 if (unlikely(head >= vq->num)) {
2012 vq_err(vq, "Guest says index %u > %u is available",
2017 /* When we start there are none of either input nor output. */
2018 *out_num = *in_num = 0;
2024 unsigned iov_count = *in_num + *out_num;
2025 if (unlikely(i >= vq->num)) {
2026 vq_err(vq, "Desc index is %u > %u, head = %u",
2030 if (unlikely(++found > vq->num)) {
2031 vq_err(vq, "Loop detected: last one at %u "
2032 "vq size %u head %u\n",
2036 ret = vhost_copy_from_user(vq, &desc, vq->desc + i,
2038 if (unlikely(ret)) {
2039 vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
2043 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT)) {
2044 ret = get_indirect(vq, iov, iov_size,
2046 log, log_num, &desc);
2047 if (unlikely(ret < 0)) {
2049 vq_err(vq, "Failure detected "
2050 "in indirect descriptor at idx %d\n", i);
2056 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
2057 access = VHOST_ACCESS_WO;
2059 access = VHOST_ACCESS_RO;
2060 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
2061 vhost32_to_cpu(vq, desc.len), iov + iov_count,
2062 iov_size - iov_count, access);
2063 if (unlikely(ret < 0)) {
2065 vq_err(vq, "Translation failure %d descriptor idx %d\n",
2069 if (access == VHOST_ACCESS_WO) {
2070 /* If this is an input descriptor,
2071 * increment that count. */
2073 if (unlikely(log)) {
2074 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
2075 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
2079 /* If it's an output descriptor, they're all supposed
2080 * to come before any input descriptors. */
2081 if (unlikely(*in_num)) {
2082 vq_err(vq, "Descriptor has out after in: "
2088 } while ((i = next_desc(vq, &desc)) != -1);
2090 /* On success, increment avail index. */
2091 vq->last_avail_idx++;
2093 /* Assume notifications from guest are disabled at this point,
2094 * if they aren't we would need to update avail_event index. */
2095 BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
2098 EXPORT_SYMBOL_GPL(vhost_get_vq_desc);
2100 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
2101 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
2103 vq->last_avail_idx -= n;
2105 EXPORT_SYMBOL_GPL(vhost_discard_vq_desc);
2107 /* After we've used one of their buffers, we tell them about it. We'll then
2108 * want to notify the guest, using eventfd. */
2109 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
2111 struct vring_used_elem heads = {
2112 cpu_to_vhost32(vq, head),
2113 cpu_to_vhost32(vq, len)
2116 return vhost_add_used_n(vq, &heads, 1);
2118 EXPORT_SYMBOL_GPL(vhost_add_used);
2120 static int __vhost_add_used_n(struct vhost_virtqueue *vq,
2121 struct vring_used_elem *heads,
2124 struct vring_used_elem __user *used;
2128 start = vq->last_used_idx & (vq->num - 1);
2129 used = vq->used->ring + start;
2131 if (vhost_put_user(vq, heads[0].id, &used->id)) {
2132 vq_err(vq, "Failed to write used id");
2135 if (vhost_put_user(vq, heads[0].len, &used->len)) {
2136 vq_err(vq, "Failed to write used len");
2139 } else if (vhost_copy_to_user(vq, used, heads, count * sizeof *used)) {
2140 vq_err(vq, "Failed to write used");
2143 if (unlikely(vq->log_used)) {
2144 /* Make sure data is seen before log. */
2146 /* Log used ring entry write. */
2147 log_write(vq->log_base,
2149 ((void __user *)used - (void __user *)vq->used),
2150 count * sizeof *used);
2152 old = vq->last_used_idx;
2153 new = (vq->last_used_idx += count);
2154 /* If the driver never bothers to signal in a very long while,
2155 * used index might wrap around. If that happens, invalidate
2156 * signalled_used index we stored. TODO: make sure driver
2157 * signals at least once in 2^16 and remove this. */
2158 if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old)))
2159 vq->signalled_used_valid = false;
2163 /* After we've used one of their buffers, we tell them about it. We'll then
2164 * want to notify the guest, using eventfd. */
2165 int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
2170 start = vq->last_used_idx & (vq->num - 1);
2171 n = vq->num - start;
2173 r = __vhost_add_used_n(vq, heads, n);
2179 r = __vhost_add_used_n(vq, heads, count);
2181 /* Make sure buffer is written before we update index. */
2183 if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->last_used_idx),
2185 vq_err(vq, "Failed to increment used idx");
2188 if (unlikely(vq->log_used)) {
2189 /* Log used index update. */
2190 log_write(vq->log_base,
2191 vq->log_addr + offsetof(struct vring_used, idx),
2192 sizeof vq->used->idx);
2194 eventfd_signal(vq->log_ctx, 1);
2198 EXPORT_SYMBOL_GPL(vhost_add_used_n);
2200 static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2205 /* Flush out used index updates. This is paired
2206 * with the barrier that the Guest executes when enabling
2210 if (vhost_has_feature(vq, VIRTIO_F_NOTIFY_ON_EMPTY) &&
2211 unlikely(vq->avail_idx == vq->last_avail_idx))
2214 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2216 if (vhost_get_avail(vq, flags, &vq->avail->flags)) {
2217 vq_err(vq, "Failed to get flags");
2220 return !(flags & cpu_to_vhost16(vq, VRING_AVAIL_F_NO_INTERRUPT));
2222 old = vq->signalled_used;
2223 v = vq->signalled_used_valid;
2224 new = vq->signalled_used = vq->last_used_idx;
2225 vq->signalled_used_valid = true;
2230 if (vhost_get_avail(vq, event, vhost_used_event(vq))) {
2231 vq_err(vq, "Failed to get used event idx");
2234 return vring_need_event(vhost16_to_cpu(vq, event), new, old);
2237 /* This actually signals the guest, using eventfd. */
2238 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2240 /* Signal the Guest tell them we used something up. */
2241 if (vq->call_ctx && vhost_notify(dev, vq))
2242 eventfd_signal(vq->call_ctx, 1);
2244 EXPORT_SYMBOL_GPL(vhost_signal);
2246 /* And here's the combo meal deal. Supersize me! */
2247 void vhost_add_used_and_signal(struct vhost_dev *dev,
2248 struct vhost_virtqueue *vq,
2249 unsigned int head, int len)
2251 vhost_add_used(vq, head, len);
2252 vhost_signal(dev, vq);
2254 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal);
2256 /* multi-buffer version of vhost_add_used_and_signal */
2257 void vhost_add_used_and_signal_n(struct vhost_dev *dev,
2258 struct vhost_virtqueue *vq,
2259 struct vring_used_elem *heads, unsigned count)
2261 vhost_add_used_n(vq, heads, count);
2262 vhost_signal(dev, vq);
2264 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n);
2266 /* return true if we're sure that avaiable ring is empty */
2267 bool vhost_vq_avail_empty(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2269 __virtio16 avail_idx;
2272 if (vq->avail_idx != vq->last_avail_idx)
2275 r = vhost_get_avail(vq, avail_idx, &vq->avail->idx);
2278 vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
2280 return vq->avail_idx == vq->last_avail_idx;
2282 EXPORT_SYMBOL_GPL(vhost_vq_avail_empty);
2284 /* OK, now we need to know about added descriptors. */
2285 bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2287 __virtio16 avail_idx;
2290 if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
2292 vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
2293 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2294 r = vhost_update_used_flags(vq);
2296 vq_err(vq, "Failed to enable notification at %p: %d\n",
2297 &vq->used->flags, r);
2301 r = vhost_update_avail_event(vq, vq->avail_idx);
2303 vq_err(vq, "Failed to update avail event index at %p: %d\n",
2304 vhost_avail_event(vq), r);
2308 /* They could have slipped one in as we were doing that: make
2309 * sure it's written, then check again. */
2311 r = vhost_get_avail(vq, avail_idx, &vq->avail->idx);
2313 vq_err(vq, "Failed to check avail idx at %p: %d\n",
2314 &vq->avail->idx, r);
2318 return vhost16_to_cpu(vq, avail_idx) != vq->avail_idx;
2320 EXPORT_SYMBOL_GPL(vhost_enable_notify);
2322 /* We don't need to be notified again. */
2323 void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2327 if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
2329 vq->used_flags |= VRING_USED_F_NO_NOTIFY;
2330 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2331 r = vhost_update_used_flags(vq);
2333 vq_err(vq, "Failed to enable notification at %p: %d\n",
2334 &vq->used->flags, r);
2337 EXPORT_SYMBOL_GPL(vhost_disable_notify);
2339 /* Create a new message. */
2340 struct vhost_msg_node *vhost_new_msg(struct vhost_virtqueue *vq, int type)
2342 struct vhost_msg_node *node = kmalloc(sizeof *node, GFP_KERNEL);
2346 node->msg.type = type;
2349 EXPORT_SYMBOL_GPL(vhost_new_msg);
2351 void vhost_enqueue_msg(struct vhost_dev *dev, struct list_head *head,
2352 struct vhost_msg_node *node)
2354 spin_lock(&dev->iotlb_lock);
2355 list_add_tail(&node->node, head);
2356 spin_unlock(&dev->iotlb_lock);
2358 wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
2360 EXPORT_SYMBOL_GPL(vhost_enqueue_msg);
2362 struct vhost_msg_node *vhost_dequeue_msg(struct vhost_dev *dev,
2363 struct list_head *head)
2365 struct vhost_msg_node *node = NULL;
2367 spin_lock(&dev->iotlb_lock);
2368 if (!list_empty(head)) {
2369 node = list_first_entry(head, struct vhost_msg_node,
2371 list_del(&node->node);
2373 spin_unlock(&dev->iotlb_lock);
2377 EXPORT_SYMBOL_GPL(vhost_dequeue_msg);
2380 static int __init vhost_init(void)
2385 static void __exit vhost_exit(void)
2389 module_init(vhost_init);
2390 module_exit(vhost_exit);
2392 MODULE_VERSION("0.0.1");
2393 MODULE_LICENSE("GPL v2");
2394 MODULE_AUTHOR("Michael S. Tsirkin");
2395 MODULE_DESCRIPTION("Host kernel accelerator for virtio");