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 int 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 int 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 int 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 int 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 int 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 int 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 int 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 int 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 int vhost_vq_access_ok(struct vhost_virtqueue *vq)
1247 int ret = vq_log_access_ok(vq, vq->log_base);
1249 if (ret || vq->iotlb)
1252 return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used);
1254 EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
1256 static struct vhost_umem *vhost_umem_alloc(void)
1258 struct vhost_umem *umem = kvzalloc(sizeof(*umem), GFP_KERNEL);
1263 umem->umem_tree = RB_ROOT_CACHED;
1265 INIT_LIST_HEAD(&umem->umem_list);
1270 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
1272 struct vhost_memory mem, *newmem;
1273 struct vhost_memory_region *region;
1274 struct vhost_umem *newumem, *oldumem;
1275 unsigned long size = offsetof(struct vhost_memory, regions);
1278 if (copy_from_user(&mem, m, size))
1282 if (mem.nregions > max_mem_regions)
1284 newmem = kvzalloc(size + mem.nregions * sizeof(*m->regions), GFP_KERNEL);
1288 memcpy(newmem, &mem, size);
1289 if (copy_from_user(newmem->regions, m->regions,
1290 mem.nregions * sizeof *m->regions)) {
1295 newumem = vhost_umem_alloc();
1301 for (region = newmem->regions;
1302 region < newmem->regions + mem.nregions;
1304 if (vhost_new_umem_range(newumem,
1305 region->guest_phys_addr,
1306 region->memory_size,
1307 region->guest_phys_addr +
1308 region->memory_size - 1,
1309 region->userspace_addr,
1314 if (!memory_access_ok(d, newumem, 0))
1320 /* All memory accesses are done under some VQ mutex. */
1321 for (i = 0; i < d->nvqs; ++i) {
1322 mutex_lock(&d->vqs[i]->mutex);
1323 d->vqs[i]->umem = newumem;
1324 mutex_unlock(&d->vqs[i]->mutex);
1328 vhost_umem_clean(oldumem);
1332 vhost_umem_clean(newumem);
1337 long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
1339 struct file *eventfp, *filep = NULL;
1340 bool pollstart = false, pollstop = false;
1341 struct eventfd_ctx *ctx = NULL;
1342 u32 __user *idxp = argp;
1343 struct vhost_virtqueue *vq;
1344 struct vhost_vring_state s;
1345 struct vhost_vring_file f;
1346 struct vhost_vring_addr a;
1350 r = get_user(idx, idxp);
1358 mutex_lock(&vq->mutex);
1361 case VHOST_SET_VRING_NUM:
1362 /* Resizing ring with an active backend?
1363 * You don't want to do that. */
1364 if (vq->private_data) {
1368 if (copy_from_user(&s, argp, sizeof s)) {
1372 if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) {
1378 case VHOST_SET_VRING_BASE:
1379 /* Moving base with an active backend?
1380 * You don't want to do that. */
1381 if (vq->private_data) {
1385 if (copy_from_user(&s, argp, sizeof s)) {
1389 if (s.num > 0xffff) {
1393 vq->last_avail_idx = s.num;
1394 /* Forget the cached index value. */
1395 vq->avail_idx = vq->last_avail_idx;
1397 case VHOST_GET_VRING_BASE:
1399 s.num = vq->last_avail_idx;
1400 if (copy_to_user(argp, &s, sizeof s))
1403 case VHOST_SET_VRING_ADDR:
1404 if (copy_from_user(&a, argp, sizeof a)) {
1408 if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) {
1412 /* For 32bit, verify that the top 32bits of the user
1413 data are set to zero. */
1414 if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr ||
1415 (u64)(unsigned long)a.used_user_addr != a.used_user_addr ||
1416 (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) {
1421 /* Make sure it's safe to cast pointers to vring types. */
1422 BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE);
1423 BUILD_BUG_ON(__alignof__ *vq->used > VRING_USED_ALIGN_SIZE);
1424 if ((a.avail_user_addr & (VRING_AVAIL_ALIGN_SIZE - 1)) ||
1425 (a.used_user_addr & (VRING_USED_ALIGN_SIZE - 1)) ||
1426 (a.log_guest_addr & (VRING_USED_ALIGN_SIZE - 1))) {
1431 /* We only verify access here if backend is configured.
1432 * If it is not, we don't as size might not have been setup.
1433 * We will verify when backend is configured. */
1434 if (vq->private_data) {
1435 if (!vq_access_ok(vq, vq->num,
1436 (void __user *)(unsigned long)a.desc_user_addr,
1437 (void __user *)(unsigned long)a.avail_user_addr,
1438 (void __user *)(unsigned long)a.used_user_addr)) {
1443 /* Also validate log access for used ring if enabled. */
1444 if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) &&
1445 !log_access_ok(vq->log_base, a.log_guest_addr,
1447 vq->num * sizeof *vq->used->ring)) {
1453 vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
1454 vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
1455 vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
1456 vq->log_addr = a.log_guest_addr;
1457 vq->used = (void __user *)(unsigned long)a.used_user_addr;
1459 case VHOST_SET_VRING_KICK:
1460 if (copy_from_user(&f, argp, sizeof f)) {
1464 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
1465 if (IS_ERR(eventfp)) {
1466 r = PTR_ERR(eventfp);
1469 if (eventfp != vq->kick) {
1470 pollstop = (filep = vq->kick) != NULL;
1471 pollstart = (vq->kick = eventfp) != NULL;
1475 case VHOST_SET_VRING_CALL:
1476 if (copy_from_user(&f, argp, sizeof f)) {
1480 ctx = f.fd == -1 ? NULL : eventfd_ctx_fdget(f.fd);
1485 swap(ctx, vq->call_ctx);
1487 case VHOST_SET_VRING_ERR:
1488 if (copy_from_user(&f, argp, sizeof f)) {
1492 ctx = f.fd == -1 ? NULL : eventfd_ctx_fdget(f.fd);
1497 swap(ctx, vq->error_ctx);
1499 case VHOST_SET_VRING_ENDIAN:
1500 r = vhost_set_vring_endian(vq, argp);
1502 case VHOST_GET_VRING_ENDIAN:
1503 r = vhost_get_vring_endian(vq, idx, argp);
1505 case VHOST_SET_VRING_BUSYLOOP_TIMEOUT:
1506 if (copy_from_user(&s, argp, sizeof(s))) {
1510 vq->busyloop_timeout = s.num;
1512 case VHOST_GET_VRING_BUSYLOOP_TIMEOUT:
1514 s.num = vq->busyloop_timeout;
1515 if (copy_to_user(argp, &s, sizeof(s)))
1522 if (pollstop && vq->handle_kick)
1523 vhost_poll_stop(&vq->poll);
1525 if (!IS_ERR_OR_NULL(ctx))
1526 eventfd_ctx_put(ctx);
1530 if (pollstart && vq->handle_kick)
1531 r = vhost_poll_start(&vq->poll, vq->kick);
1533 mutex_unlock(&vq->mutex);
1535 if (pollstop && vq->handle_kick)
1536 vhost_poll_flush(&vq->poll);
1539 EXPORT_SYMBOL_GPL(vhost_vring_ioctl);
1541 int vhost_init_device_iotlb(struct vhost_dev *d, bool enabled)
1543 struct vhost_umem *niotlb, *oiotlb;
1546 niotlb = vhost_umem_alloc();
1553 for (i = 0; i < d->nvqs; ++i) {
1554 mutex_lock(&d->vqs[i]->mutex);
1555 d->vqs[i]->iotlb = niotlb;
1556 mutex_unlock(&d->vqs[i]->mutex);
1559 vhost_umem_clean(oiotlb);
1563 EXPORT_SYMBOL_GPL(vhost_init_device_iotlb);
1565 /* Caller must have device mutex */
1566 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
1568 struct eventfd_ctx *ctx;
1573 /* If you are not the owner, you can become one */
1574 if (ioctl == VHOST_SET_OWNER) {
1575 r = vhost_dev_set_owner(d);
1579 /* You must be the owner to do anything else */
1580 r = vhost_dev_check_owner(d);
1585 case VHOST_SET_MEM_TABLE:
1586 r = vhost_set_memory(d, argp);
1588 case VHOST_SET_LOG_BASE:
1589 if (copy_from_user(&p, argp, sizeof p)) {
1593 if ((u64)(unsigned long)p != p) {
1597 for (i = 0; i < d->nvqs; ++i) {
1598 struct vhost_virtqueue *vq;
1599 void __user *base = (void __user *)(unsigned long)p;
1601 mutex_lock(&vq->mutex);
1602 /* If ring is inactive, will check when it's enabled. */
1603 if (vq->private_data && !vq_log_access_ok(vq, base))
1606 vq->log_base = base;
1607 mutex_unlock(&vq->mutex);
1610 case VHOST_SET_LOG_FD:
1611 r = get_user(fd, (int __user *)argp);
1614 ctx = fd == -1 ? NULL : eventfd_ctx_fdget(fd);
1619 swap(ctx, d->log_ctx);
1620 for (i = 0; i < d->nvqs; ++i) {
1621 mutex_lock(&d->vqs[i]->mutex);
1622 d->vqs[i]->log_ctx = d->log_ctx;
1623 mutex_unlock(&d->vqs[i]->mutex);
1626 eventfd_ctx_put(ctx);
1635 EXPORT_SYMBOL_GPL(vhost_dev_ioctl);
1637 /* TODO: This is really inefficient. We need something like get_user()
1638 * (instruction directly accesses the data, with an exception table entry
1639 * returning -EFAULT). See Documentation/x86/exception-tables.txt.
1641 static int set_bit_to_user(int nr, void __user *addr)
1643 unsigned long log = (unsigned long)addr;
1646 int bit = nr + (log % PAGE_SIZE) * 8;
1649 r = get_user_pages_fast(log, 1, 1, &page);
1653 base = kmap_atomic(page);
1655 kunmap_atomic(base);
1656 set_page_dirty_lock(page);
1661 static int log_write(void __user *log_base,
1662 u64 write_address, u64 write_length)
1664 u64 write_page = write_address / VHOST_PAGE_SIZE;
1669 write_length += write_address % VHOST_PAGE_SIZE;
1671 u64 base = (u64)(unsigned long)log_base;
1672 u64 log = base + write_page / 8;
1673 int bit = write_page % 8;
1674 if ((u64)(unsigned long)log != log)
1676 r = set_bit_to_user(bit, (void __user *)(unsigned long)log);
1679 if (write_length <= VHOST_PAGE_SIZE)
1681 write_length -= VHOST_PAGE_SIZE;
1687 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
1688 unsigned int log_num, u64 len)
1692 /* Make sure data written is seen before log. */
1694 for (i = 0; i < log_num; ++i) {
1695 u64 l = min(log[i].len, len);
1696 r = log_write(vq->log_base, log[i].addr, l);
1702 eventfd_signal(vq->log_ctx, 1);
1706 /* Length written exceeds what we have stored. This is a bug. */
1710 EXPORT_SYMBOL_GPL(vhost_log_write);
1712 static int vhost_update_used_flags(struct vhost_virtqueue *vq)
1715 if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->used_flags),
1716 &vq->used->flags) < 0)
1718 if (unlikely(vq->log_used)) {
1719 /* Make sure the flag is seen before log. */
1721 /* Log used flag write. */
1722 used = &vq->used->flags;
1723 log_write(vq->log_base, vq->log_addr +
1724 (used - (void __user *)vq->used),
1725 sizeof vq->used->flags);
1727 eventfd_signal(vq->log_ctx, 1);
1732 static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event)
1734 if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->avail_idx),
1735 vhost_avail_event(vq)))
1737 if (unlikely(vq->log_used)) {
1739 /* Make sure the event is seen before log. */
1741 /* Log avail event write */
1742 used = vhost_avail_event(vq);
1743 log_write(vq->log_base, vq->log_addr +
1744 (used - (void __user *)vq->used),
1745 sizeof *vhost_avail_event(vq));
1747 eventfd_signal(vq->log_ctx, 1);
1752 int vhost_vq_init_access(struct vhost_virtqueue *vq)
1754 __virtio16 last_used_idx;
1756 bool is_le = vq->is_le;
1758 if (!vq->private_data)
1761 vhost_init_is_le(vq);
1763 r = vhost_update_used_flags(vq);
1766 vq->signalled_used_valid = false;
1768 !access_ok(VERIFY_READ, &vq->used->idx, sizeof vq->used->idx)) {
1772 r = vhost_get_used(vq, last_used_idx, &vq->used->idx);
1774 vq_err(vq, "Can't access used idx at %p\n",
1778 vq->last_used_idx = vhost16_to_cpu(vq, last_used_idx);
1785 EXPORT_SYMBOL_GPL(vhost_vq_init_access);
1787 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
1788 struct iovec iov[], int iov_size, int access)
1790 const struct vhost_umem_node *node;
1791 struct vhost_dev *dev = vq->dev;
1792 struct vhost_umem *umem = dev->iotlb ? dev->iotlb : dev->umem;
1797 while ((u64)len > s) {
1799 if (unlikely(ret >= iov_size)) {
1804 node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
1805 addr, addr + len - 1);
1806 if (node == NULL || node->start > addr) {
1807 if (umem != dev->iotlb) {
1813 } else if (!(node->perm & access)) {
1819 size = node->size - addr + node->start;
1820 _iov->iov_len = min((u64)len - s, size);
1821 _iov->iov_base = (void __user *)(unsigned long)
1822 (node->userspace_addr + addr - node->start);
1829 vhost_iotlb_miss(vq, addr, access);
1833 /* Each buffer in the virtqueues is actually a chain of descriptors. This
1834 * function returns the next descriptor in the chain,
1835 * or -1U if we're at the end. */
1836 static unsigned next_desc(struct vhost_virtqueue *vq, struct vring_desc *desc)
1840 /* If this descriptor says it doesn't chain, we're done. */
1841 if (!(desc->flags & cpu_to_vhost16(vq, VRING_DESC_F_NEXT)))
1844 /* Check they're not leading us off end of descriptors. */
1845 next = vhost16_to_cpu(vq, READ_ONCE(desc->next));
1849 static int get_indirect(struct vhost_virtqueue *vq,
1850 struct iovec iov[], unsigned int iov_size,
1851 unsigned int *out_num, unsigned int *in_num,
1852 struct vhost_log *log, unsigned int *log_num,
1853 struct vring_desc *indirect)
1855 struct vring_desc desc;
1856 unsigned int i = 0, count, found = 0;
1857 u32 len = vhost32_to_cpu(vq, indirect->len);
1858 struct iov_iter from;
1862 if (unlikely(len % sizeof desc)) {
1863 vq_err(vq, "Invalid length in indirect descriptor: "
1864 "len 0x%llx not multiple of 0x%zx\n",
1865 (unsigned long long)len,
1870 ret = translate_desc(vq, vhost64_to_cpu(vq, indirect->addr), len, vq->indirect,
1871 UIO_MAXIOV, VHOST_ACCESS_RO);
1872 if (unlikely(ret < 0)) {
1874 vq_err(vq, "Translation failure %d in indirect.\n", ret);
1877 iov_iter_init(&from, READ, vq->indirect, ret, len);
1879 /* We will use the result as an address to read from, so most
1880 * architectures only need a compiler barrier here. */
1881 read_barrier_depends();
1883 count = len / sizeof desc;
1884 /* Buffers are chained via a 16 bit next field, so
1885 * we can have at most 2^16 of these. */
1886 if (unlikely(count > USHRT_MAX + 1)) {
1887 vq_err(vq, "Indirect buffer length too big: %d\n",
1893 unsigned iov_count = *in_num + *out_num;
1894 if (unlikely(++found > count)) {
1895 vq_err(vq, "Loop detected: last one at %u "
1896 "indirect size %u\n",
1900 if (unlikely(!copy_from_iter_full(&desc, sizeof(desc), &from))) {
1901 vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n",
1902 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
1905 if (unlikely(desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT))) {
1906 vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n",
1907 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
1911 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
1912 access = VHOST_ACCESS_WO;
1914 access = VHOST_ACCESS_RO;
1916 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
1917 vhost32_to_cpu(vq, desc.len), iov + iov_count,
1918 iov_size - iov_count, access);
1919 if (unlikely(ret < 0)) {
1921 vq_err(vq, "Translation failure %d indirect idx %d\n",
1925 /* If this is an input descriptor, increment that count. */
1926 if (access == VHOST_ACCESS_WO) {
1928 if (unlikely(log)) {
1929 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
1930 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
1934 /* If it's an output descriptor, they're all supposed
1935 * to come before any input descriptors. */
1936 if (unlikely(*in_num)) {
1937 vq_err(vq, "Indirect descriptor "
1938 "has out after in: idx %d\n", i);
1943 } while ((i = next_desc(vq, &desc)) != -1);
1947 /* This looks in the virtqueue and for the first available buffer, and converts
1948 * it to an iovec for convenient access. Since descriptors consist of some
1949 * number of output then some number of input descriptors, it's actually two
1950 * iovecs, but we pack them into one and note how many of each there were.
1952 * This function returns the descriptor number found, or vq->num (which is
1953 * never a valid descriptor number) if none was found. A negative code is
1954 * returned on error. */
1955 int vhost_get_vq_desc(struct vhost_virtqueue *vq,
1956 struct iovec iov[], unsigned int iov_size,
1957 unsigned int *out_num, unsigned int *in_num,
1958 struct vhost_log *log, unsigned int *log_num)
1960 struct vring_desc desc;
1961 unsigned int i, head, found = 0;
1963 __virtio16 avail_idx;
1964 __virtio16 ring_head;
1967 /* Check it isn't doing very strange things with descriptor numbers. */
1968 last_avail_idx = vq->last_avail_idx;
1970 if (vq->avail_idx == vq->last_avail_idx) {
1971 if (unlikely(vhost_get_avail(vq, avail_idx, &vq->avail->idx))) {
1972 vq_err(vq, "Failed to access avail idx at %p\n",
1976 vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
1978 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
1979 vq_err(vq, "Guest moved used index from %u to %u",
1980 last_avail_idx, vq->avail_idx);
1984 /* If there's nothing new since last we looked, return
1987 if (vq->avail_idx == last_avail_idx)
1990 /* Only get avail ring entries after they have been
1996 /* Grab the next descriptor number they're advertising, and increment
1997 * the index we've seen. */
1998 if (unlikely(vhost_get_avail(vq, ring_head,
1999 &vq->avail->ring[last_avail_idx & (vq->num - 1)]))) {
2000 vq_err(vq, "Failed to read head: idx %d address %p\n",
2002 &vq->avail->ring[last_avail_idx % vq->num]);
2006 head = vhost16_to_cpu(vq, ring_head);
2008 /* If their number is silly, that's an error. */
2009 if (unlikely(head >= vq->num)) {
2010 vq_err(vq, "Guest says index %u > %u is available",
2015 /* When we start there are none of either input nor output. */
2016 *out_num = *in_num = 0;
2022 unsigned iov_count = *in_num + *out_num;
2023 if (unlikely(i >= vq->num)) {
2024 vq_err(vq, "Desc index is %u > %u, head = %u",
2028 if (unlikely(++found > vq->num)) {
2029 vq_err(vq, "Loop detected: last one at %u "
2030 "vq size %u head %u\n",
2034 ret = vhost_copy_from_user(vq, &desc, vq->desc + i,
2036 if (unlikely(ret)) {
2037 vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
2041 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT)) {
2042 ret = get_indirect(vq, iov, iov_size,
2044 log, log_num, &desc);
2045 if (unlikely(ret < 0)) {
2047 vq_err(vq, "Failure detected "
2048 "in indirect descriptor at idx %d\n", i);
2054 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
2055 access = VHOST_ACCESS_WO;
2057 access = VHOST_ACCESS_RO;
2058 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
2059 vhost32_to_cpu(vq, desc.len), iov + iov_count,
2060 iov_size - iov_count, access);
2061 if (unlikely(ret < 0)) {
2063 vq_err(vq, "Translation failure %d descriptor idx %d\n",
2067 if (access == VHOST_ACCESS_WO) {
2068 /* If this is an input descriptor,
2069 * increment that count. */
2071 if (unlikely(log)) {
2072 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
2073 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
2077 /* If it's an output descriptor, they're all supposed
2078 * to come before any input descriptors. */
2079 if (unlikely(*in_num)) {
2080 vq_err(vq, "Descriptor has out after in: "
2086 } while ((i = next_desc(vq, &desc)) != -1);
2088 /* On success, increment avail index. */
2089 vq->last_avail_idx++;
2091 /* Assume notifications from guest are disabled at this point,
2092 * if they aren't we would need to update avail_event index. */
2093 BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
2096 EXPORT_SYMBOL_GPL(vhost_get_vq_desc);
2098 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
2099 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
2101 vq->last_avail_idx -= n;
2103 EXPORT_SYMBOL_GPL(vhost_discard_vq_desc);
2105 /* After we've used one of their buffers, we tell them about it. We'll then
2106 * want to notify the guest, using eventfd. */
2107 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
2109 struct vring_used_elem heads = {
2110 cpu_to_vhost32(vq, head),
2111 cpu_to_vhost32(vq, len)
2114 return vhost_add_used_n(vq, &heads, 1);
2116 EXPORT_SYMBOL_GPL(vhost_add_used);
2118 static int __vhost_add_used_n(struct vhost_virtqueue *vq,
2119 struct vring_used_elem *heads,
2122 struct vring_used_elem __user *used;
2126 start = vq->last_used_idx & (vq->num - 1);
2127 used = vq->used->ring + start;
2129 if (vhost_put_user(vq, heads[0].id, &used->id)) {
2130 vq_err(vq, "Failed to write used id");
2133 if (vhost_put_user(vq, heads[0].len, &used->len)) {
2134 vq_err(vq, "Failed to write used len");
2137 } else if (vhost_copy_to_user(vq, used, heads, count * sizeof *used)) {
2138 vq_err(vq, "Failed to write used");
2141 if (unlikely(vq->log_used)) {
2142 /* Make sure data is seen before log. */
2144 /* Log used ring entry write. */
2145 log_write(vq->log_base,
2147 ((void __user *)used - (void __user *)vq->used),
2148 count * sizeof *used);
2150 old = vq->last_used_idx;
2151 new = (vq->last_used_idx += count);
2152 /* If the driver never bothers to signal in a very long while,
2153 * used index might wrap around. If that happens, invalidate
2154 * signalled_used index we stored. TODO: make sure driver
2155 * signals at least once in 2^16 and remove this. */
2156 if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old)))
2157 vq->signalled_used_valid = false;
2161 /* After we've used one of their buffers, we tell them about it. We'll then
2162 * want to notify the guest, using eventfd. */
2163 int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
2168 start = vq->last_used_idx & (vq->num - 1);
2169 n = vq->num - start;
2171 r = __vhost_add_used_n(vq, heads, n);
2177 r = __vhost_add_used_n(vq, heads, count);
2179 /* Make sure buffer is written before we update index. */
2181 if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->last_used_idx),
2183 vq_err(vq, "Failed to increment used idx");
2186 if (unlikely(vq->log_used)) {
2187 /* Log used index update. */
2188 log_write(vq->log_base,
2189 vq->log_addr + offsetof(struct vring_used, idx),
2190 sizeof vq->used->idx);
2192 eventfd_signal(vq->log_ctx, 1);
2196 EXPORT_SYMBOL_GPL(vhost_add_used_n);
2198 static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2203 /* Flush out used index updates. This is paired
2204 * with the barrier that the Guest executes when enabling
2208 if (vhost_has_feature(vq, VIRTIO_F_NOTIFY_ON_EMPTY) &&
2209 unlikely(vq->avail_idx == vq->last_avail_idx))
2212 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2214 if (vhost_get_avail(vq, flags, &vq->avail->flags)) {
2215 vq_err(vq, "Failed to get flags");
2218 return !(flags & cpu_to_vhost16(vq, VRING_AVAIL_F_NO_INTERRUPT));
2220 old = vq->signalled_used;
2221 v = vq->signalled_used_valid;
2222 new = vq->signalled_used = vq->last_used_idx;
2223 vq->signalled_used_valid = true;
2228 if (vhost_get_avail(vq, event, vhost_used_event(vq))) {
2229 vq_err(vq, "Failed to get used event idx");
2232 return vring_need_event(vhost16_to_cpu(vq, event), new, old);
2235 /* This actually signals the guest, using eventfd. */
2236 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2238 /* Signal the Guest tell them we used something up. */
2239 if (vq->call_ctx && vhost_notify(dev, vq))
2240 eventfd_signal(vq->call_ctx, 1);
2242 EXPORT_SYMBOL_GPL(vhost_signal);
2244 /* And here's the combo meal deal. Supersize me! */
2245 void vhost_add_used_and_signal(struct vhost_dev *dev,
2246 struct vhost_virtqueue *vq,
2247 unsigned int head, int len)
2249 vhost_add_used(vq, head, len);
2250 vhost_signal(dev, vq);
2252 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal);
2254 /* multi-buffer version of vhost_add_used_and_signal */
2255 void vhost_add_used_and_signal_n(struct vhost_dev *dev,
2256 struct vhost_virtqueue *vq,
2257 struct vring_used_elem *heads, unsigned count)
2259 vhost_add_used_n(vq, heads, count);
2260 vhost_signal(dev, vq);
2262 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n);
2264 /* return true if we're sure that avaiable ring is empty */
2265 bool vhost_vq_avail_empty(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2267 __virtio16 avail_idx;
2270 if (vq->avail_idx != vq->last_avail_idx)
2273 r = vhost_get_avail(vq, avail_idx, &vq->avail->idx);
2276 vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
2278 return vq->avail_idx == vq->last_avail_idx;
2280 EXPORT_SYMBOL_GPL(vhost_vq_avail_empty);
2282 /* OK, now we need to know about added descriptors. */
2283 bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2285 __virtio16 avail_idx;
2288 if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
2290 vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
2291 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2292 r = vhost_update_used_flags(vq);
2294 vq_err(vq, "Failed to enable notification at %p: %d\n",
2295 &vq->used->flags, r);
2299 r = vhost_update_avail_event(vq, vq->avail_idx);
2301 vq_err(vq, "Failed to update avail event index at %p: %d\n",
2302 vhost_avail_event(vq), r);
2306 /* They could have slipped one in as we were doing that: make
2307 * sure it's written, then check again. */
2309 r = vhost_get_avail(vq, avail_idx, &vq->avail->idx);
2311 vq_err(vq, "Failed to check avail idx at %p: %d\n",
2312 &vq->avail->idx, r);
2316 return vhost16_to_cpu(vq, avail_idx) != vq->avail_idx;
2318 EXPORT_SYMBOL_GPL(vhost_enable_notify);
2320 /* We don't need to be notified again. */
2321 void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2325 if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
2327 vq->used_flags |= VRING_USED_F_NO_NOTIFY;
2328 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2329 r = vhost_update_used_flags(vq);
2331 vq_err(vq, "Failed to enable notification at %p: %d\n",
2332 &vq->used->flags, r);
2335 EXPORT_SYMBOL_GPL(vhost_disable_notify);
2337 /* Create a new message. */
2338 struct vhost_msg_node *vhost_new_msg(struct vhost_virtqueue *vq, int type)
2340 struct vhost_msg_node *node = kmalloc(sizeof *node, GFP_KERNEL);
2344 node->msg.type = type;
2347 EXPORT_SYMBOL_GPL(vhost_new_msg);
2349 void vhost_enqueue_msg(struct vhost_dev *dev, struct list_head *head,
2350 struct vhost_msg_node *node)
2352 spin_lock(&dev->iotlb_lock);
2353 list_add_tail(&node->node, head);
2354 spin_unlock(&dev->iotlb_lock);
2356 wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
2358 EXPORT_SYMBOL_GPL(vhost_enqueue_msg);
2360 struct vhost_msg_node *vhost_dequeue_msg(struct vhost_dev *dev,
2361 struct list_head *head)
2363 struct vhost_msg_node *node = NULL;
2365 spin_lock(&dev->iotlb_lock);
2366 if (!list_empty(head)) {
2367 node = list_first_entry(head, struct vhost_msg_node,
2369 list_del(&node->node);
2371 spin_unlock(&dev->iotlb_lock);
2375 EXPORT_SYMBOL_GPL(vhost_dequeue_msg);
2378 static int __init vhost_init(void)
2383 static void __exit vhost_exit(void)
2387 module_init(vhost_init);
2388 module_exit(vhost_exit);
2390 MODULE_VERSION("0.0.1");
2391 MODULE_LICENSE("GPL v2");
2392 MODULE_AUTHOR("Michael S. Tsirkin");
2393 MODULE_DESCRIPTION("Host kernel accelerator for virtio");