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_t *wait, unsigned mode, int sync,
171 struct vhost_poll *poll = container_of(wait, struct vhost_poll, wait);
173 if (!((unsigned long)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);
184 init_waitqueue_head(&work->done);
186 EXPORT_SYMBOL_GPL(vhost_work_init);
188 /* Init poll structure */
189 void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
190 unsigned long mask, struct vhost_dev *dev)
192 init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup);
193 init_poll_funcptr(&poll->table, vhost_poll_func);
198 vhost_work_init(&poll->work, fn);
200 EXPORT_SYMBOL_GPL(vhost_poll_init);
202 /* Start polling a file. We add ourselves to file's wait queue. The caller must
203 * keep a reference to a file until after vhost_poll_stop is called. */
204 int vhost_poll_start(struct vhost_poll *poll, struct file *file)
212 mask = file->f_op->poll(file, &poll->table);
214 vhost_poll_wakeup(&poll->wait, 0, 0, (void *)mask);
215 if (mask & POLLERR) {
217 remove_wait_queue(poll->wqh, &poll->wait);
223 EXPORT_SYMBOL_GPL(vhost_poll_start);
225 /* Stop polling a file. After this function returns, it becomes safe to drop the
226 * file reference. You must also flush afterwards. */
227 void vhost_poll_stop(struct vhost_poll *poll)
230 remove_wait_queue(poll->wqh, &poll->wait);
234 EXPORT_SYMBOL_GPL(vhost_poll_stop);
236 void vhost_work_flush(struct vhost_dev *dev, struct vhost_work *work)
238 struct vhost_flush_struct flush;
241 init_completion(&flush.wait_event);
242 vhost_work_init(&flush.work, vhost_flush_work);
244 vhost_work_queue(dev, &flush.work);
245 wait_for_completion(&flush.wait_event);
248 EXPORT_SYMBOL_GPL(vhost_work_flush);
250 /* Flush any work that has been scheduled. When calling this, don't hold any
251 * locks that are also used by the callback. */
252 void vhost_poll_flush(struct vhost_poll *poll)
254 vhost_work_flush(poll->dev, &poll->work);
256 EXPORT_SYMBOL_GPL(vhost_poll_flush);
258 void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work)
263 if (!test_and_set_bit(VHOST_WORK_QUEUED, &work->flags)) {
264 /* We can only add the work to the list after we're
265 * sure it was not in the list.
266 * test_and_set_bit() implies a memory barrier.
268 llist_add(&work->node, &dev->work_list);
269 wake_up_process(dev->worker);
272 EXPORT_SYMBOL_GPL(vhost_work_queue);
274 /* A lockless hint for busy polling code to exit the loop */
275 bool vhost_has_work(struct vhost_dev *dev)
277 return !llist_empty(&dev->work_list);
279 EXPORT_SYMBOL_GPL(vhost_has_work);
281 void vhost_poll_queue(struct vhost_poll *poll)
283 vhost_work_queue(poll->dev, &poll->work);
285 EXPORT_SYMBOL_GPL(vhost_poll_queue);
287 static void vhost_vq_reset(struct vhost_dev *dev,
288 struct vhost_virtqueue *vq)
294 vq->last_avail_idx = 0;
295 vq->last_used_event = 0;
297 vq->last_used_idx = 0;
298 vq->signalled_used = 0;
299 vq->signalled_used_valid = false;
301 vq->log_used = false;
302 vq->log_addr = -1ull;
303 vq->private_data = NULL;
304 vq->acked_features = 0;
306 vq->error_ctx = NULL;
312 vhost_reset_is_le(vq);
313 vhost_disable_cross_endian(vq);
314 vq->busyloop_timeout = 0;
319 static int vhost_worker(void *data)
321 struct vhost_dev *dev = data;
322 struct vhost_work *work, *work_next;
323 struct llist_node *node;
324 mm_segment_t oldfs = get_fs();
330 /* mb paired w/ kthread_stop */
331 set_current_state(TASK_INTERRUPTIBLE);
333 if (kthread_should_stop()) {
334 __set_current_state(TASK_RUNNING);
338 node = llist_del_all(&dev->work_list);
342 node = llist_reverse_order(node);
343 /* make sure flag is seen after deletion */
345 llist_for_each_entry_safe(work, work_next, node, node) {
346 clear_bit(VHOST_WORK_QUEUED, &work->flags);
347 __set_current_state(TASK_RUNNING);
358 static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq)
368 /* Helper to allocate iovec buffers for all vqs. */
369 static long vhost_dev_alloc_iovecs(struct vhost_dev *dev)
371 struct vhost_virtqueue *vq;
374 for (i = 0; i < dev->nvqs; ++i) {
376 vq->indirect = kmalloc(sizeof *vq->indirect * UIO_MAXIOV,
378 vq->log = kmalloc(sizeof *vq->log * UIO_MAXIOV, GFP_KERNEL);
379 vq->heads = kmalloc(sizeof *vq->heads * UIO_MAXIOV, GFP_KERNEL);
380 if (!vq->indirect || !vq->log || !vq->heads)
387 vhost_vq_free_iovecs(dev->vqs[i]);
391 static void vhost_dev_free_iovecs(struct vhost_dev *dev)
395 for (i = 0; i < dev->nvqs; ++i)
396 vhost_vq_free_iovecs(dev->vqs[i]);
399 void vhost_dev_init(struct vhost_dev *dev,
400 struct vhost_virtqueue **vqs, int nvqs)
402 struct vhost_virtqueue *vq;
407 mutex_init(&dev->mutex);
409 dev->log_file = NULL;
414 init_llist_head(&dev->work_list);
415 init_waitqueue_head(&dev->wait);
416 INIT_LIST_HEAD(&dev->read_list);
417 INIT_LIST_HEAD(&dev->pending_list);
418 spin_lock_init(&dev->iotlb_lock);
421 for (i = 0; i < dev->nvqs; ++i) {
427 mutex_init(&vq->mutex);
428 vhost_vq_reset(dev, vq);
430 vhost_poll_init(&vq->poll, vq->handle_kick,
434 EXPORT_SYMBOL_GPL(vhost_dev_init);
436 /* Caller should have device mutex */
437 long vhost_dev_check_owner(struct vhost_dev *dev)
439 /* Are you the owner? If not, I don't think you mean to do that */
440 return dev->mm == current->mm ? 0 : -EPERM;
442 EXPORT_SYMBOL_GPL(vhost_dev_check_owner);
444 struct vhost_attach_cgroups_struct {
445 struct vhost_work work;
446 struct task_struct *owner;
450 static void vhost_attach_cgroups_work(struct vhost_work *work)
452 struct vhost_attach_cgroups_struct *s;
454 s = container_of(work, struct vhost_attach_cgroups_struct, work);
455 s->ret = cgroup_attach_task_all(s->owner, current);
458 static int vhost_attach_cgroups(struct vhost_dev *dev)
460 struct vhost_attach_cgroups_struct attach;
462 attach.owner = current;
463 vhost_work_init(&attach.work, vhost_attach_cgroups_work);
464 vhost_work_queue(dev, &attach.work);
465 vhost_work_flush(dev, &attach.work);
469 /* Caller should have device mutex */
470 bool vhost_dev_has_owner(struct vhost_dev *dev)
474 EXPORT_SYMBOL_GPL(vhost_dev_has_owner);
476 /* Caller should have device mutex */
477 long vhost_dev_set_owner(struct vhost_dev *dev)
479 struct task_struct *worker;
482 /* Is there an owner already? */
483 if (vhost_dev_has_owner(dev)) {
488 /* No owner, become one */
489 dev->mm = get_task_mm(current);
490 worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid);
491 if (IS_ERR(worker)) {
492 err = PTR_ERR(worker);
496 dev->worker = worker;
497 wake_up_process(worker); /* avoid contributing to loadavg */
499 err = vhost_attach_cgroups(dev);
503 err = vhost_dev_alloc_iovecs(dev);
509 kthread_stop(worker);
518 EXPORT_SYMBOL_GPL(vhost_dev_set_owner);
520 static void *vhost_kvzalloc(unsigned long size)
522 void *n = kzalloc(size, GFP_KERNEL | __GFP_NOWARN | __GFP_REPEAT);
529 struct vhost_umem *vhost_dev_reset_owner_prepare(void)
531 return vhost_kvzalloc(sizeof(struct vhost_umem));
533 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner_prepare);
535 /* Caller should have device mutex */
536 void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_umem *umem)
540 vhost_dev_cleanup(dev, true);
542 /* Restore memory to default empty mapping. */
543 INIT_LIST_HEAD(&umem->umem_list);
545 /* We don't need VQ locks below since vhost_dev_cleanup makes sure
546 * VQs aren't running.
548 for (i = 0; i < dev->nvqs; ++i)
549 dev->vqs[i]->umem = umem;
551 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner);
553 void vhost_dev_stop(struct vhost_dev *dev)
557 for (i = 0; i < dev->nvqs; ++i) {
558 if (dev->vqs[i]->kick && dev->vqs[i]->handle_kick) {
559 vhost_poll_stop(&dev->vqs[i]->poll);
560 vhost_poll_flush(&dev->vqs[i]->poll);
564 EXPORT_SYMBOL_GPL(vhost_dev_stop);
566 static void vhost_umem_free(struct vhost_umem *umem,
567 struct vhost_umem_node *node)
569 vhost_umem_interval_tree_remove(node, &umem->umem_tree);
570 list_del(&node->link);
575 static void vhost_umem_clean(struct vhost_umem *umem)
577 struct vhost_umem_node *node, *tmp;
582 list_for_each_entry_safe(node, tmp, &umem->umem_list, link)
583 vhost_umem_free(umem, node);
588 static void vhost_clear_msg(struct vhost_dev *dev)
590 struct vhost_msg_node *node, *n;
592 spin_lock(&dev->iotlb_lock);
594 list_for_each_entry_safe(node, n, &dev->read_list, node) {
595 list_del(&node->node);
599 list_for_each_entry_safe(node, n, &dev->pending_list, node) {
600 list_del(&node->node);
604 spin_unlock(&dev->iotlb_lock);
607 /* Caller should have device mutex if and only if locked is set */
608 void vhost_dev_cleanup(struct vhost_dev *dev, bool locked)
612 for (i = 0; i < dev->nvqs; ++i) {
613 if (dev->vqs[i]->error_ctx)
614 eventfd_ctx_put(dev->vqs[i]->error_ctx);
615 if (dev->vqs[i]->error)
616 fput(dev->vqs[i]->error);
617 if (dev->vqs[i]->kick)
618 fput(dev->vqs[i]->kick);
619 if (dev->vqs[i]->call_ctx)
620 eventfd_ctx_put(dev->vqs[i]->call_ctx);
621 if (dev->vqs[i]->call)
622 fput(dev->vqs[i]->call);
623 vhost_vq_reset(dev, dev->vqs[i]);
625 vhost_dev_free_iovecs(dev);
627 eventfd_ctx_put(dev->log_ctx);
631 dev->log_file = NULL;
632 /* No one will access memory at this point */
633 vhost_umem_clean(dev->umem);
635 vhost_umem_clean(dev->iotlb);
637 vhost_clear_msg(dev);
638 wake_up_interruptible_poll(&dev->wait, POLLIN | POLLRDNORM);
639 WARN_ON(!llist_empty(&dev->work_list));
641 kthread_stop(dev->worker);
648 EXPORT_SYMBOL_GPL(vhost_dev_cleanup);
650 static int log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
652 u64 a = addr / VHOST_PAGE_SIZE / 8;
654 /* Make sure 64 bit math will not overflow. */
655 if (a > ULONG_MAX - (unsigned long)log_base ||
656 a + (unsigned long)log_base > ULONG_MAX)
659 return access_ok(VERIFY_WRITE, log_base + a,
660 (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8);
663 static bool vhost_overflow(u64 uaddr, u64 size)
665 /* Make sure 64 bit math will not overflow. */
666 return uaddr > ULONG_MAX || size > ULONG_MAX || uaddr > ULONG_MAX - size;
669 /* Caller should have vq mutex and device mutex. */
670 static int vq_memory_access_ok(void __user *log_base, struct vhost_umem *umem,
673 struct vhost_umem_node *node;
678 list_for_each_entry(node, &umem->umem_list, link) {
679 unsigned long a = node->userspace_addr;
681 if (vhost_overflow(node->userspace_addr, node->size))
685 if (!access_ok(VERIFY_WRITE, (void __user *)a,
688 else if (log_all && !log_access_ok(log_base,
696 /* Can we switch to this memory table? */
697 /* Caller should have device mutex but not vq mutex */
698 static int memory_access_ok(struct vhost_dev *d, struct vhost_umem *umem,
703 for (i = 0; i < d->nvqs; ++i) {
707 mutex_lock(&d->vqs[i]->mutex);
708 log = log_all || vhost_has_feature(d->vqs[i], VHOST_F_LOG_ALL);
709 /* If ring is inactive, will check when it's enabled. */
710 if (d->vqs[i]->private_data)
711 ok = vq_memory_access_ok(d->vqs[i]->log_base,
715 mutex_unlock(&d->vqs[i]->mutex);
722 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
723 struct iovec iov[], int iov_size, int access);
725 static int vhost_copy_to_user(struct vhost_virtqueue *vq, void __user *to,
726 const void *from, unsigned size)
731 return __copy_to_user(to, from, size);
733 /* This function should be called after iotlb
734 * prefetch, which means we're sure that all vq
735 * could be access through iotlb. So -EAGAIN should
736 * not happen in this case.
738 /* TODO: more fast path */
740 ret = translate_desc(vq, (u64)(uintptr_t)to, size, vq->iotlb_iov,
741 ARRAY_SIZE(vq->iotlb_iov),
745 iov_iter_init(&t, WRITE, vq->iotlb_iov, ret, size);
746 ret = copy_to_iter(from, size, &t);
754 static int vhost_copy_from_user(struct vhost_virtqueue *vq, void *to,
755 void __user *from, unsigned size)
760 return __copy_from_user(to, from, size);
762 /* This function should be called after iotlb
763 * prefetch, which means we're sure that vq
764 * could be access through iotlb. So -EAGAIN should
765 * not happen in this case.
767 /* TODO: more fast path */
769 ret = translate_desc(vq, (u64)(uintptr_t)from, size, vq->iotlb_iov,
770 ARRAY_SIZE(vq->iotlb_iov),
773 vq_err(vq, "IOTLB translation failure: uaddr "
774 "%p size 0x%llx\n", from,
775 (unsigned long long) size);
778 iov_iter_init(&f, READ, vq->iotlb_iov, ret, size);
779 ret = copy_from_iter(to, size, &f);
788 static void __user *__vhost_get_user(struct vhost_virtqueue *vq,
789 void __user *addr, unsigned size)
793 /* This function should be called after iotlb
794 * prefetch, which means we're sure that vq
795 * could be access through iotlb. So -EAGAIN should
796 * not happen in this case.
798 /* TODO: more fast path */
799 ret = translate_desc(vq, (u64)(uintptr_t)addr, size, vq->iotlb_iov,
800 ARRAY_SIZE(vq->iotlb_iov),
803 vq_err(vq, "IOTLB translation failure: uaddr "
804 "%p size 0x%llx\n", addr,
805 (unsigned long long) size);
809 if (ret != 1 || vq->iotlb_iov[0].iov_len != size) {
810 vq_err(vq, "Non atomic userspace memory access: uaddr "
811 "%p size 0x%llx\n", addr,
812 (unsigned long long) size);
816 return vq->iotlb_iov[0].iov_base;
819 #define vhost_put_user(vq, x, ptr) \
823 ret = __put_user(x, ptr); \
825 __typeof__(ptr) to = \
826 (__typeof__(ptr)) __vhost_get_user(vq, ptr, sizeof(*ptr)); \
828 ret = __put_user(x, to); \
835 #define vhost_get_user(vq, x, ptr) \
839 ret = __get_user(x, ptr); \
841 __typeof__(ptr) from = \
842 (__typeof__(ptr)) __vhost_get_user(vq, ptr, sizeof(*ptr)); \
844 ret = __get_user(x, from); \
851 static void vhost_dev_lock_vqs(struct vhost_dev *d)
854 for (i = 0; i < d->nvqs; ++i)
855 mutex_lock(&d->vqs[i]->mutex);
858 static void vhost_dev_unlock_vqs(struct vhost_dev *d)
861 for (i = 0; i < d->nvqs; ++i)
862 mutex_unlock(&d->vqs[i]->mutex);
865 static int vhost_new_umem_range(struct vhost_umem *umem,
866 u64 start, u64 size, u64 end,
867 u64 userspace_addr, int perm)
869 struct vhost_umem_node *tmp, *node = kmalloc(sizeof(*node), GFP_ATOMIC);
874 if (umem->numem == max_iotlb_entries) {
875 tmp = list_first_entry(&umem->umem_list, typeof(*tmp), link);
876 vhost_umem_free(umem, tmp);
882 node->userspace_addr = userspace_addr;
884 INIT_LIST_HEAD(&node->link);
885 list_add_tail(&node->link, &umem->umem_list);
886 vhost_umem_interval_tree_insert(node, &umem->umem_tree);
892 static void vhost_del_umem_range(struct vhost_umem *umem,
895 struct vhost_umem_node *node;
897 while ((node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
899 vhost_umem_free(umem, node);
902 static void vhost_iotlb_notify_vq(struct vhost_dev *d,
903 struct vhost_iotlb_msg *msg)
905 struct vhost_msg_node *node, *n;
907 spin_lock(&d->iotlb_lock);
909 list_for_each_entry_safe(node, n, &d->pending_list, node) {
910 struct vhost_iotlb_msg *vq_msg = &node->msg.iotlb;
911 if (msg->iova <= vq_msg->iova &&
912 msg->iova + msg->size - 1 > vq_msg->iova &&
913 vq_msg->type == VHOST_IOTLB_MISS) {
914 vhost_poll_queue(&node->vq->poll);
915 list_del(&node->node);
920 spin_unlock(&d->iotlb_lock);
923 static int umem_access_ok(u64 uaddr, u64 size, int access)
925 unsigned long a = uaddr;
927 /* Make sure 64 bit math will not overflow. */
928 if (vhost_overflow(uaddr, size))
931 if ((access & VHOST_ACCESS_RO) &&
932 !access_ok(VERIFY_READ, (void __user *)a, size))
934 if ((access & VHOST_ACCESS_WO) &&
935 !access_ok(VERIFY_WRITE, (void __user *)a, size))
940 static int vhost_process_iotlb_msg(struct vhost_dev *dev,
941 struct vhost_iotlb_msg *msg)
945 vhost_dev_lock_vqs(dev);
947 case VHOST_IOTLB_UPDATE:
952 if (umem_access_ok(msg->uaddr, msg->size, msg->perm)) {
956 if (vhost_new_umem_range(dev->iotlb, msg->iova, msg->size,
957 msg->iova + msg->size - 1,
958 msg->uaddr, msg->perm)) {
962 vhost_iotlb_notify_vq(dev, msg);
964 case VHOST_IOTLB_INVALIDATE:
965 vhost_del_umem_range(dev->iotlb, msg->iova,
966 msg->iova + msg->size - 1);
973 vhost_dev_unlock_vqs(dev);
976 ssize_t vhost_chr_write_iter(struct vhost_dev *dev,
977 struct iov_iter *from)
979 struct vhost_msg_node node;
980 unsigned size = sizeof(struct vhost_msg);
984 if (iov_iter_count(from) < size)
986 ret = copy_from_iter(&node.msg, size, from);
990 switch (node.msg.type) {
991 case VHOST_IOTLB_MSG:
992 err = vhost_process_iotlb_msg(dev, &node.msg.iotlb);
1004 EXPORT_SYMBOL(vhost_chr_write_iter);
1006 unsigned int vhost_chr_poll(struct file *file, struct vhost_dev *dev,
1009 unsigned int mask = 0;
1011 poll_wait(file, &dev->wait, wait);
1013 if (!list_empty(&dev->read_list))
1014 mask |= POLLIN | POLLRDNORM;
1018 EXPORT_SYMBOL(vhost_chr_poll);
1020 ssize_t vhost_chr_read_iter(struct vhost_dev *dev, struct iov_iter *to,
1024 struct vhost_msg_node *node;
1026 unsigned size = sizeof(struct vhost_msg);
1028 if (iov_iter_count(to) < size)
1033 prepare_to_wait(&dev->wait, &wait,
1034 TASK_INTERRUPTIBLE);
1036 node = vhost_dequeue_msg(dev, &dev->read_list);
1043 if (signal_pending(current)) {
1056 finish_wait(&dev->wait, &wait);
1059 ret = copy_to_iter(&node->msg, size, to);
1061 if (ret != size || node->msg.type != VHOST_IOTLB_MISS) {
1066 vhost_enqueue_msg(dev, &dev->pending_list, node);
1071 EXPORT_SYMBOL_GPL(vhost_chr_read_iter);
1073 static int vhost_iotlb_miss(struct vhost_virtqueue *vq, u64 iova, int access)
1075 struct vhost_dev *dev = vq->dev;
1076 struct vhost_msg_node *node;
1077 struct vhost_iotlb_msg *msg;
1079 node = vhost_new_msg(vq, VHOST_IOTLB_MISS);
1083 msg = &node->msg.iotlb;
1084 msg->type = VHOST_IOTLB_MISS;
1088 vhost_enqueue_msg(dev, &dev->read_list, node);
1093 static int vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
1094 struct vring_desc __user *desc,
1095 struct vring_avail __user *avail,
1096 struct vring_used __user *used)
1099 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
1101 return access_ok(VERIFY_READ, desc, num * sizeof *desc) &&
1102 access_ok(VERIFY_READ, avail,
1103 sizeof *avail + num * sizeof *avail->ring + s) &&
1104 access_ok(VERIFY_WRITE, used,
1105 sizeof *used + num * sizeof *used->ring + s);
1108 static int iotlb_access_ok(struct vhost_virtqueue *vq,
1109 int access, u64 addr, u64 len)
1111 const struct vhost_umem_node *node;
1112 struct vhost_umem *umem = vq->iotlb;
1116 node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
1119 if (node == NULL || node->start > addr) {
1120 vhost_iotlb_miss(vq, addr, access);
1122 } else if (!(node->perm & access)) {
1123 /* Report the possible access violation by
1124 * request another translation from userspace.
1129 size = node->size - addr + node->start;
1137 int vq_iotlb_prefetch(struct vhost_virtqueue *vq)
1139 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
1140 unsigned int num = vq->num;
1145 return iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->desc,
1146 num * sizeof *vq->desc) &&
1147 iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->avail,
1149 num * sizeof *vq->avail->ring + s) &&
1150 iotlb_access_ok(vq, VHOST_ACCESS_WO, (u64)(uintptr_t)vq->used,
1152 num * sizeof *vq->used->ring + s);
1154 EXPORT_SYMBOL_GPL(vq_iotlb_prefetch);
1156 /* Can we log writes? */
1157 /* Caller should have device mutex but not vq mutex */
1158 int vhost_log_access_ok(struct vhost_dev *dev)
1160 return memory_access_ok(dev, dev->umem, 1);
1162 EXPORT_SYMBOL_GPL(vhost_log_access_ok);
1164 /* Verify access for write logging. */
1165 /* Caller should have vq mutex and device mutex */
1166 static int vq_log_access_ok(struct vhost_virtqueue *vq,
1167 void __user *log_base)
1169 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
1171 return vq_memory_access_ok(log_base, vq->umem,
1172 vhost_has_feature(vq, VHOST_F_LOG_ALL)) &&
1173 (!vq->log_used || log_access_ok(log_base, vq->log_addr,
1175 vq->num * sizeof *vq->used->ring + s));
1178 /* Can we start vq? */
1179 /* Caller should have vq mutex and device mutex */
1180 int vhost_vq_access_ok(struct vhost_virtqueue *vq)
1183 /* When device IOTLB was used, the access validation
1184 * will be validated during prefetching.
1188 return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used) &&
1189 vq_log_access_ok(vq, vq->log_base);
1191 EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
1193 static struct vhost_umem *vhost_umem_alloc(void)
1195 struct vhost_umem *umem = vhost_kvzalloc(sizeof(*umem));
1200 umem->umem_tree = RB_ROOT;
1202 INIT_LIST_HEAD(&umem->umem_list);
1207 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
1209 struct vhost_memory mem, *newmem;
1210 struct vhost_memory_region *region;
1211 struct vhost_umem *newumem, *oldumem;
1212 unsigned long size = offsetof(struct vhost_memory, regions);
1215 if (copy_from_user(&mem, m, size))
1219 if (mem.nregions > max_mem_regions)
1221 newmem = vhost_kvzalloc(size + mem.nregions * sizeof(*m->regions));
1225 memcpy(newmem, &mem, size);
1226 if (copy_from_user(newmem->regions, m->regions,
1227 mem.nregions * sizeof *m->regions)) {
1232 newumem = vhost_umem_alloc();
1238 for (region = newmem->regions;
1239 region < newmem->regions + mem.nregions;
1241 if (vhost_new_umem_range(newumem,
1242 region->guest_phys_addr,
1243 region->memory_size,
1244 region->guest_phys_addr +
1245 region->memory_size - 1,
1246 region->userspace_addr,
1251 if (!memory_access_ok(d, newumem, 0))
1257 /* All memory accesses are done under some VQ mutex. */
1258 for (i = 0; i < d->nvqs; ++i) {
1259 mutex_lock(&d->vqs[i]->mutex);
1260 d->vqs[i]->umem = newumem;
1261 mutex_unlock(&d->vqs[i]->mutex);
1265 vhost_umem_clean(oldumem);
1269 vhost_umem_clean(newumem);
1274 long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp)
1276 struct file *eventfp, *filep = NULL;
1277 bool pollstart = false, pollstop = false;
1278 struct eventfd_ctx *ctx = NULL;
1279 u32 __user *idxp = argp;
1280 struct vhost_virtqueue *vq;
1281 struct vhost_vring_state s;
1282 struct vhost_vring_file f;
1283 struct vhost_vring_addr a;
1287 r = get_user(idx, idxp);
1295 mutex_lock(&vq->mutex);
1298 case VHOST_SET_VRING_NUM:
1299 /* Resizing ring with an active backend?
1300 * You don't want to do that. */
1301 if (vq->private_data) {
1305 if (copy_from_user(&s, argp, sizeof s)) {
1309 if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) {
1315 case VHOST_SET_VRING_BASE:
1316 /* Moving base with an active backend?
1317 * You don't want to do that. */
1318 if (vq->private_data) {
1322 if (copy_from_user(&s, argp, sizeof s)) {
1326 if (s.num > 0xffff) {
1330 vq->last_avail_idx = vq->last_used_event = s.num;
1331 /* Forget the cached index value. */
1332 vq->avail_idx = vq->last_avail_idx;
1334 case VHOST_GET_VRING_BASE:
1336 s.num = vq->last_avail_idx;
1337 if (copy_to_user(argp, &s, sizeof s))
1340 case VHOST_SET_VRING_ADDR:
1341 if (copy_from_user(&a, argp, sizeof a)) {
1345 if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) {
1349 /* For 32bit, verify that the top 32bits of the user
1350 data are set to zero. */
1351 if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr ||
1352 (u64)(unsigned long)a.used_user_addr != a.used_user_addr ||
1353 (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) {
1358 /* Make sure it's safe to cast pointers to vring types. */
1359 BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE);
1360 BUILD_BUG_ON(__alignof__ *vq->used > VRING_USED_ALIGN_SIZE);
1361 if ((a.avail_user_addr & (VRING_AVAIL_ALIGN_SIZE - 1)) ||
1362 (a.used_user_addr & (VRING_USED_ALIGN_SIZE - 1)) ||
1363 (a.log_guest_addr & (VRING_USED_ALIGN_SIZE - 1))) {
1368 /* We only verify access here if backend is configured.
1369 * If it is not, we don't as size might not have been setup.
1370 * We will verify when backend is configured. */
1371 if (vq->private_data) {
1372 if (!vq_access_ok(vq, vq->num,
1373 (void __user *)(unsigned long)a.desc_user_addr,
1374 (void __user *)(unsigned long)a.avail_user_addr,
1375 (void __user *)(unsigned long)a.used_user_addr)) {
1380 /* Also validate log access for used ring if enabled. */
1381 if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) &&
1382 !log_access_ok(vq->log_base, a.log_guest_addr,
1384 vq->num * sizeof *vq->used->ring)) {
1390 vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
1391 vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
1392 vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
1393 vq->log_addr = a.log_guest_addr;
1394 vq->used = (void __user *)(unsigned long)a.used_user_addr;
1396 case VHOST_SET_VRING_KICK:
1397 if (copy_from_user(&f, argp, sizeof f)) {
1401 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
1402 if (IS_ERR(eventfp)) {
1403 r = PTR_ERR(eventfp);
1406 if (eventfp != vq->kick) {
1407 pollstop = (filep = vq->kick) != NULL;
1408 pollstart = (vq->kick = eventfp) != NULL;
1412 case VHOST_SET_VRING_CALL:
1413 if (copy_from_user(&f, argp, sizeof f)) {
1417 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
1418 if (IS_ERR(eventfp)) {
1419 r = PTR_ERR(eventfp);
1422 if (eventfp != vq->call) {
1426 vq->call_ctx = eventfp ?
1427 eventfd_ctx_fileget(eventfp) : NULL;
1431 case VHOST_SET_VRING_ERR:
1432 if (copy_from_user(&f, argp, sizeof f)) {
1436 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
1437 if (IS_ERR(eventfp)) {
1438 r = PTR_ERR(eventfp);
1441 if (eventfp != vq->error) {
1443 vq->error = eventfp;
1444 ctx = vq->error_ctx;
1445 vq->error_ctx = eventfp ?
1446 eventfd_ctx_fileget(eventfp) : NULL;
1450 case VHOST_SET_VRING_ENDIAN:
1451 r = vhost_set_vring_endian(vq, argp);
1453 case VHOST_GET_VRING_ENDIAN:
1454 r = vhost_get_vring_endian(vq, idx, argp);
1456 case VHOST_SET_VRING_BUSYLOOP_TIMEOUT:
1457 if (copy_from_user(&s, argp, sizeof(s))) {
1461 vq->busyloop_timeout = s.num;
1463 case VHOST_GET_VRING_BUSYLOOP_TIMEOUT:
1465 s.num = vq->busyloop_timeout;
1466 if (copy_to_user(argp, &s, sizeof(s)))
1473 if (pollstop && vq->handle_kick)
1474 vhost_poll_stop(&vq->poll);
1477 eventfd_ctx_put(ctx);
1481 if (pollstart && vq->handle_kick)
1482 r = vhost_poll_start(&vq->poll, vq->kick);
1484 mutex_unlock(&vq->mutex);
1486 if (pollstop && vq->handle_kick)
1487 vhost_poll_flush(&vq->poll);
1490 EXPORT_SYMBOL_GPL(vhost_vring_ioctl);
1492 int vhost_init_device_iotlb(struct vhost_dev *d, bool enabled)
1494 struct vhost_umem *niotlb, *oiotlb;
1497 niotlb = vhost_umem_alloc();
1504 for (i = 0; i < d->nvqs; ++i) {
1505 mutex_lock(&d->vqs[i]->mutex);
1506 d->vqs[i]->iotlb = niotlb;
1507 mutex_unlock(&d->vqs[i]->mutex);
1510 vhost_umem_clean(oiotlb);
1514 EXPORT_SYMBOL_GPL(vhost_init_device_iotlb);
1516 /* Caller must have device mutex */
1517 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
1519 struct file *eventfp, *filep = NULL;
1520 struct eventfd_ctx *ctx = NULL;
1525 /* If you are not the owner, you can become one */
1526 if (ioctl == VHOST_SET_OWNER) {
1527 r = vhost_dev_set_owner(d);
1531 /* You must be the owner to do anything else */
1532 r = vhost_dev_check_owner(d);
1537 case VHOST_SET_MEM_TABLE:
1538 r = vhost_set_memory(d, argp);
1540 case VHOST_SET_LOG_BASE:
1541 if (copy_from_user(&p, argp, sizeof p)) {
1545 if ((u64)(unsigned long)p != p) {
1549 for (i = 0; i < d->nvqs; ++i) {
1550 struct vhost_virtqueue *vq;
1551 void __user *base = (void __user *)(unsigned long)p;
1553 mutex_lock(&vq->mutex);
1554 /* If ring is inactive, will check when it's enabled. */
1555 if (vq->private_data && !vq_log_access_ok(vq, base))
1558 vq->log_base = base;
1559 mutex_unlock(&vq->mutex);
1562 case VHOST_SET_LOG_FD:
1563 r = get_user(fd, (int __user *)argp);
1566 eventfp = fd == -1 ? NULL : eventfd_fget(fd);
1567 if (IS_ERR(eventfp)) {
1568 r = PTR_ERR(eventfp);
1571 if (eventfp != d->log_file) {
1572 filep = d->log_file;
1573 d->log_file = eventfp;
1575 d->log_ctx = eventfp ?
1576 eventfd_ctx_fileget(eventfp) : NULL;
1579 for (i = 0; i < d->nvqs; ++i) {
1580 mutex_lock(&d->vqs[i]->mutex);
1581 d->vqs[i]->log_ctx = d->log_ctx;
1582 mutex_unlock(&d->vqs[i]->mutex);
1585 eventfd_ctx_put(ctx);
1596 EXPORT_SYMBOL_GPL(vhost_dev_ioctl);
1598 /* TODO: This is really inefficient. We need something like get_user()
1599 * (instruction directly accesses the data, with an exception table entry
1600 * returning -EFAULT). See Documentation/x86/exception-tables.txt.
1602 static int set_bit_to_user(int nr, void __user *addr)
1604 unsigned long log = (unsigned long)addr;
1607 int bit = nr + (log % PAGE_SIZE) * 8;
1610 r = get_user_pages_fast(log, 1, 1, &page);
1614 base = kmap_atomic(page);
1616 kunmap_atomic(base);
1617 set_page_dirty_lock(page);
1622 static int log_write(void __user *log_base,
1623 u64 write_address, u64 write_length)
1625 u64 write_page = write_address / VHOST_PAGE_SIZE;
1630 write_length += write_address % VHOST_PAGE_SIZE;
1632 u64 base = (u64)(unsigned long)log_base;
1633 u64 log = base + write_page / 8;
1634 int bit = write_page % 8;
1635 if ((u64)(unsigned long)log != log)
1637 r = set_bit_to_user(bit, (void __user *)(unsigned long)log);
1640 if (write_length <= VHOST_PAGE_SIZE)
1642 write_length -= VHOST_PAGE_SIZE;
1648 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
1649 unsigned int log_num, u64 len)
1653 /* Make sure data written is seen before log. */
1655 for (i = 0; i < log_num; ++i) {
1656 u64 l = min(log[i].len, len);
1657 r = log_write(vq->log_base, log[i].addr, l);
1663 eventfd_signal(vq->log_ctx, 1);
1667 /* Length written exceeds what we have stored. This is a bug. */
1671 EXPORT_SYMBOL_GPL(vhost_log_write);
1673 static int vhost_update_used_flags(struct vhost_virtqueue *vq)
1676 if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->used_flags),
1677 &vq->used->flags) < 0)
1679 if (unlikely(vq->log_used)) {
1680 /* Make sure the flag is seen before log. */
1682 /* Log used flag write. */
1683 used = &vq->used->flags;
1684 log_write(vq->log_base, vq->log_addr +
1685 (used - (void __user *)vq->used),
1686 sizeof vq->used->flags);
1688 eventfd_signal(vq->log_ctx, 1);
1693 static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event)
1695 if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->avail_idx),
1696 vhost_avail_event(vq)))
1698 if (unlikely(vq->log_used)) {
1700 /* Make sure the event is seen before log. */
1702 /* Log avail event write */
1703 used = vhost_avail_event(vq);
1704 log_write(vq->log_base, vq->log_addr +
1705 (used - (void __user *)vq->used),
1706 sizeof *vhost_avail_event(vq));
1708 eventfd_signal(vq->log_ctx, 1);
1713 int vhost_vq_init_access(struct vhost_virtqueue *vq)
1715 __virtio16 last_used_idx;
1717 bool is_le = vq->is_le;
1719 if (!vq->private_data)
1722 vhost_init_is_le(vq);
1724 r = vhost_update_used_flags(vq);
1727 vq->signalled_used_valid = false;
1729 !access_ok(VERIFY_READ, &vq->used->idx, sizeof vq->used->idx)) {
1733 r = vhost_get_user(vq, last_used_idx, &vq->used->idx);
1735 vq_err(vq, "Can't access used idx at %p\n",
1739 vq->last_used_idx = vhost16_to_cpu(vq, last_used_idx);
1746 EXPORT_SYMBOL_GPL(vhost_vq_init_access);
1748 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
1749 struct iovec iov[], int iov_size, int access)
1751 const struct vhost_umem_node *node;
1752 struct vhost_dev *dev = vq->dev;
1753 struct vhost_umem *umem = dev->iotlb ? dev->iotlb : dev->umem;
1758 while ((u64)len > s) {
1760 if (unlikely(ret >= iov_size)) {
1765 node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
1766 addr, addr + len - 1);
1767 if (node == NULL || node->start > addr) {
1768 if (umem != dev->iotlb) {
1774 } else if (!(node->perm & access)) {
1780 size = node->size - addr + node->start;
1781 _iov->iov_len = min((u64)len - s, size);
1782 _iov->iov_base = (void __user *)(unsigned long)
1783 (node->userspace_addr + addr - node->start);
1790 vhost_iotlb_miss(vq, addr, access);
1794 /* Each buffer in the virtqueues is actually a chain of descriptors. This
1795 * function returns the next descriptor in the chain,
1796 * or -1U if we're at the end. */
1797 static unsigned next_desc(struct vhost_virtqueue *vq, struct vring_desc *desc)
1801 /* If this descriptor says it doesn't chain, we're done. */
1802 if (!(desc->flags & cpu_to_vhost16(vq, VRING_DESC_F_NEXT)))
1805 /* Check they're not leading us off end of descriptors. */
1806 next = vhost16_to_cpu(vq, desc->next);
1807 /* Make sure compiler knows to grab that: we don't want it changing! */
1808 /* We will use the result as an index in an array, so most
1809 * architectures only need a compiler barrier here. */
1810 read_barrier_depends();
1815 static int get_indirect(struct vhost_virtqueue *vq,
1816 struct iovec iov[], unsigned int iov_size,
1817 unsigned int *out_num, unsigned int *in_num,
1818 struct vhost_log *log, unsigned int *log_num,
1819 struct vring_desc *indirect)
1821 struct vring_desc desc;
1822 unsigned int i = 0, count, found = 0;
1823 u32 len = vhost32_to_cpu(vq, indirect->len);
1824 struct iov_iter from;
1828 if (unlikely(len % sizeof desc)) {
1829 vq_err(vq, "Invalid length in indirect descriptor: "
1830 "len 0x%llx not multiple of 0x%zx\n",
1831 (unsigned long long)len,
1836 ret = translate_desc(vq, vhost64_to_cpu(vq, indirect->addr), len, vq->indirect,
1837 UIO_MAXIOV, VHOST_ACCESS_RO);
1838 if (unlikely(ret < 0)) {
1840 vq_err(vq, "Translation failure %d in indirect.\n", ret);
1843 iov_iter_init(&from, READ, vq->indirect, ret, len);
1845 /* We will use the result as an address to read from, so most
1846 * architectures only need a compiler barrier here. */
1847 read_barrier_depends();
1849 count = len / sizeof desc;
1850 /* Buffers are chained via a 16 bit next field, so
1851 * we can have at most 2^16 of these. */
1852 if (unlikely(count > USHRT_MAX + 1)) {
1853 vq_err(vq, "Indirect buffer length too big: %d\n",
1859 unsigned iov_count = *in_num + *out_num;
1860 if (unlikely(++found > count)) {
1861 vq_err(vq, "Loop detected: last one at %u "
1862 "indirect size %u\n",
1866 if (unlikely(!copy_from_iter_full(&desc, sizeof(desc), &from))) {
1867 vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n",
1868 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
1871 if (unlikely(desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT))) {
1872 vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n",
1873 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc);
1877 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
1878 access = VHOST_ACCESS_WO;
1880 access = VHOST_ACCESS_RO;
1882 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
1883 vhost32_to_cpu(vq, desc.len), iov + iov_count,
1884 iov_size - iov_count, access);
1885 if (unlikely(ret < 0)) {
1887 vq_err(vq, "Translation failure %d indirect idx %d\n",
1891 /* If this is an input descriptor, increment that count. */
1892 if (access == VHOST_ACCESS_WO) {
1894 if (unlikely(log)) {
1895 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
1896 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
1900 /* If it's an output descriptor, they're all supposed
1901 * to come before any input descriptors. */
1902 if (unlikely(*in_num)) {
1903 vq_err(vq, "Indirect descriptor "
1904 "has out after in: idx %d\n", i);
1909 } while ((i = next_desc(vq, &desc)) != -1);
1913 /* This looks in the virtqueue and for the first available buffer, and converts
1914 * it to an iovec for convenient access. Since descriptors consist of some
1915 * number of output then some number of input descriptors, it's actually two
1916 * iovecs, but we pack them into one and note how many of each there were.
1918 * This function returns the descriptor number found, or vq->num (which is
1919 * never a valid descriptor number) if none was found. A negative code is
1920 * returned on error. */
1921 int vhost_get_vq_desc(struct vhost_virtqueue *vq,
1922 struct iovec iov[], unsigned int iov_size,
1923 unsigned int *out_num, unsigned int *in_num,
1924 struct vhost_log *log, unsigned int *log_num)
1926 struct vring_desc desc;
1927 unsigned int i, head, found = 0;
1929 __virtio16 avail_idx;
1930 __virtio16 ring_head;
1933 /* Check it isn't doing very strange things with descriptor numbers. */
1934 last_avail_idx = vq->last_avail_idx;
1935 if (unlikely(vhost_get_user(vq, avail_idx, &vq->avail->idx))) {
1936 vq_err(vq, "Failed to access avail idx at %p\n",
1940 vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
1942 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
1943 vq_err(vq, "Guest moved used index from %u to %u",
1944 last_avail_idx, vq->avail_idx);
1948 /* If there's nothing new since last we looked, return invalid. */
1949 if (vq->avail_idx == last_avail_idx)
1952 /* Only get avail ring entries after they have been exposed by guest. */
1955 /* Grab the next descriptor number they're advertising, and increment
1956 * the index we've seen. */
1957 if (unlikely(vhost_get_user(vq, ring_head,
1958 &vq->avail->ring[last_avail_idx & (vq->num - 1)]))) {
1959 vq_err(vq, "Failed to read head: idx %d address %p\n",
1961 &vq->avail->ring[last_avail_idx % vq->num]);
1965 head = vhost16_to_cpu(vq, ring_head);
1967 /* If their number is silly, that's an error. */
1968 if (unlikely(head >= vq->num)) {
1969 vq_err(vq, "Guest says index %u > %u is available",
1974 /* When we start there are none of either input nor output. */
1975 *out_num = *in_num = 0;
1981 unsigned iov_count = *in_num + *out_num;
1982 if (unlikely(i >= vq->num)) {
1983 vq_err(vq, "Desc index is %u > %u, head = %u",
1987 if (unlikely(++found > vq->num)) {
1988 vq_err(vq, "Loop detected: last one at %u "
1989 "vq size %u head %u\n",
1993 ret = vhost_copy_from_user(vq, &desc, vq->desc + i,
1995 if (unlikely(ret)) {
1996 vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
2000 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT)) {
2001 ret = get_indirect(vq, iov, iov_size,
2003 log, log_num, &desc);
2004 if (unlikely(ret < 0)) {
2006 vq_err(vq, "Failure detected "
2007 "in indirect descriptor at idx %d\n", i);
2013 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
2014 access = VHOST_ACCESS_WO;
2016 access = VHOST_ACCESS_RO;
2017 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
2018 vhost32_to_cpu(vq, desc.len), iov + iov_count,
2019 iov_size - iov_count, access);
2020 if (unlikely(ret < 0)) {
2022 vq_err(vq, "Translation failure %d descriptor idx %d\n",
2026 if (access == VHOST_ACCESS_WO) {
2027 /* If this is an input descriptor,
2028 * increment that count. */
2030 if (unlikely(log)) {
2031 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
2032 log[*log_num].len = vhost32_to_cpu(vq, desc.len);
2036 /* If it's an output descriptor, they're all supposed
2037 * to come before any input descriptors. */
2038 if (unlikely(*in_num)) {
2039 vq_err(vq, "Descriptor has out after in: "
2045 } while ((i = next_desc(vq, &desc)) != -1);
2047 /* On success, increment avail index. */
2048 vq->last_avail_idx++;
2050 /* Assume notifications from guest are disabled at this point,
2051 * if they aren't we would need to update avail_event index. */
2052 BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
2055 EXPORT_SYMBOL_GPL(vhost_get_vq_desc);
2057 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
2058 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
2060 vq->last_avail_idx -= n;
2062 EXPORT_SYMBOL_GPL(vhost_discard_vq_desc);
2064 /* After we've used one of their buffers, we tell them about it. We'll then
2065 * want to notify the guest, using eventfd. */
2066 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
2068 struct vring_used_elem heads = {
2069 cpu_to_vhost32(vq, head),
2070 cpu_to_vhost32(vq, len)
2073 return vhost_add_used_n(vq, &heads, 1);
2075 EXPORT_SYMBOL_GPL(vhost_add_used);
2077 static int __vhost_add_used_n(struct vhost_virtqueue *vq,
2078 struct vring_used_elem *heads,
2081 struct vring_used_elem __user *used;
2085 start = vq->last_used_idx & (vq->num - 1);
2086 used = vq->used->ring + start;
2088 if (vhost_put_user(vq, heads[0].id, &used->id)) {
2089 vq_err(vq, "Failed to write used id");
2092 if (vhost_put_user(vq, heads[0].len, &used->len)) {
2093 vq_err(vq, "Failed to write used len");
2096 } else if (vhost_copy_to_user(vq, used, heads, count * sizeof *used)) {
2097 vq_err(vq, "Failed to write used");
2100 if (unlikely(vq->log_used)) {
2101 /* Make sure data is seen before log. */
2103 /* Log used ring entry write. */
2104 log_write(vq->log_base,
2106 ((void __user *)used - (void __user *)vq->used),
2107 count * sizeof *used);
2109 old = vq->last_used_idx;
2110 new = (vq->last_used_idx += count);
2111 /* If the driver never bothers to signal in a very long while,
2112 * used index might wrap around. If that happens, invalidate
2113 * signalled_used index we stored. TODO: make sure driver
2114 * signals at least once in 2^16 and remove this. */
2115 if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old)))
2116 vq->signalled_used_valid = false;
2120 /* After we've used one of their buffers, we tell them about it. We'll then
2121 * want to notify the guest, using eventfd. */
2122 int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
2127 start = vq->last_used_idx & (vq->num - 1);
2128 n = vq->num - start;
2130 r = __vhost_add_used_n(vq, heads, n);
2136 r = __vhost_add_used_n(vq, heads, count);
2138 /* Make sure buffer is written before we update index. */
2140 if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->last_used_idx),
2142 vq_err(vq, "Failed to increment used idx");
2145 if (unlikely(vq->log_used)) {
2146 /* Log used index update. */
2147 log_write(vq->log_base,
2148 vq->log_addr + offsetof(struct vring_used, idx),
2149 sizeof vq->used->idx);
2151 eventfd_signal(vq->log_ctx, 1);
2155 EXPORT_SYMBOL_GPL(vhost_add_used_n);
2157 static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2163 if (vhost_has_feature(vq, VIRTIO_F_NOTIFY_ON_EMPTY) &&
2164 unlikely(vq->avail_idx == vq->last_avail_idx))
2167 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2169 /* Flush out used index updates. This is paired
2170 * with the barrier that the Guest executes when enabling
2173 if (vhost_get_user(vq, flags, &vq->avail->flags)) {
2174 vq_err(vq, "Failed to get flags");
2177 return !(flags & cpu_to_vhost16(vq, VRING_AVAIL_F_NO_INTERRUPT));
2179 old = vq->signalled_used;
2180 v = vq->signalled_used_valid;
2181 new = vq->signalled_used = vq->last_used_idx;
2182 vq->signalled_used_valid = true;
2187 /* We're sure if the following conditions are met, there's no
2188 * need to notify guest:
2189 * 1) cached used event is ahead of new
2190 * 2) old to new updating does not cross cached used event. */
2191 if (vring_need_event(vq->last_used_event, new + vq->num, new) &&
2192 !vring_need_event(vq->last_used_event, new, old))
2195 /* Flush out used index updates. This is paired
2196 * with the barrier that the Guest executes when enabling
2200 if (vhost_get_user(vq, event, vhost_used_event(vq))) {
2201 vq_err(vq, "Failed to get used event idx");
2204 vq->last_used_event = vhost16_to_cpu(vq, event);
2206 return vring_need_event(vq->last_used_event, new, old);
2209 /* This actually signals the guest, using eventfd. */
2210 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2212 /* Signal the Guest tell them we used something up. */
2213 if (vq->call_ctx && vhost_notify(dev, vq))
2214 eventfd_signal(vq->call_ctx, 1);
2216 EXPORT_SYMBOL_GPL(vhost_signal);
2218 /* And here's the combo meal deal. Supersize me! */
2219 void vhost_add_used_and_signal(struct vhost_dev *dev,
2220 struct vhost_virtqueue *vq,
2221 unsigned int head, int len)
2223 vhost_add_used(vq, head, len);
2224 vhost_signal(dev, vq);
2226 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal);
2228 /* multi-buffer version of vhost_add_used_and_signal */
2229 void vhost_add_used_and_signal_n(struct vhost_dev *dev,
2230 struct vhost_virtqueue *vq,
2231 struct vring_used_elem *heads, unsigned count)
2233 vhost_add_used_n(vq, heads, count);
2234 vhost_signal(dev, vq);
2236 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n);
2238 /* return true if we're sure that avaiable ring is empty */
2239 bool vhost_vq_avail_empty(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2241 __virtio16 avail_idx;
2244 if (vq->avail_idx != vq->last_avail_idx)
2247 r = vhost_get_user(vq, avail_idx, &vq->avail->idx);
2250 vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
2252 return vq->avail_idx == vq->last_avail_idx;
2254 EXPORT_SYMBOL_GPL(vhost_vq_avail_empty);
2256 /* OK, now we need to know about added descriptors. */
2257 bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2259 __virtio16 avail_idx;
2262 if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
2264 vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
2265 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2266 r = vhost_update_used_flags(vq);
2268 vq_err(vq, "Failed to enable notification at %p: %d\n",
2269 &vq->used->flags, r);
2273 r = vhost_update_avail_event(vq, vq->avail_idx);
2275 vq_err(vq, "Failed to update avail event index at %p: %d\n",
2276 vhost_avail_event(vq), r);
2280 /* They could have slipped one in as we were doing that: make
2281 * sure it's written, then check again. */
2283 r = vhost_get_user(vq, avail_idx, &vq->avail->idx);
2285 vq_err(vq, "Failed to check avail idx at %p: %d\n",
2286 &vq->avail->idx, r);
2290 return vhost16_to_cpu(vq, avail_idx) != vq->avail_idx;
2292 EXPORT_SYMBOL_GPL(vhost_enable_notify);
2294 /* We don't need to be notified again. */
2295 void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
2299 if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
2301 vq->used_flags |= VRING_USED_F_NO_NOTIFY;
2302 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
2303 r = vhost_update_used_flags(vq);
2305 vq_err(vq, "Failed to enable notification at %p: %d\n",
2306 &vq->used->flags, r);
2309 EXPORT_SYMBOL_GPL(vhost_disable_notify);
2311 /* Create a new message. */
2312 struct vhost_msg_node *vhost_new_msg(struct vhost_virtqueue *vq, int type)
2314 struct vhost_msg_node *node = kmalloc(sizeof *node, GFP_KERNEL);
2318 node->msg.type = type;
2321 EXPORT_SYMBOL_GPL(vhost_new_msg);
2323 void vhost_enqueue_msg(struct vhost_dev *dev, struct list_head *head,
2324 struct vhost_msg_node *node)
2326 spin_lock(&dev->iotlb_lock);
2327 list_add_tail(&node->node, head);
2328 spin_unlock(&dev->iotlb_lock);
2330 wake_up_interruptible_poll(&dev->wait, POLLIN | POLLRDNORM);
2332 EXPORT_SYMBOL_GPL(vhost_enqueue_msg);
2334 struct vhost_msg_node *vhost_dequeue_msg(struct vhost_dev *dev,
2335 struct list_head *head)
2337 struct vhost_msg_node *node = NULL;
2339 spin_lock(&dev->iotlb_lock);
2340 if (!list_empty(head)) {
2341 node = list_first_entry(head, struct vhost_msg_node,
2343 list_del(&node->node);
2345 spin_unlock(&dev->iotlb_lock);
2349 EXPORT_SYMBOL_GPL(vhost_dequeue_msg);
2352 static int __init vhost_init(void)
2357 static void __exit vhost_exit(void)
2361 module_init(vhost_init);
2362 module_exit(vhost_exit);
2364 MODULE_VERSION("0.0.1");
2365 MODULE_LICENSE("GPL v2");
2366 MODULE_AUTHOR("Michael S. Tsirkin");
2367 MODULE_DESCRIPTION("Host kernel accelerator for virtio");