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/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/virtio_net.h>
18 #include <linux/miscdevice.h>
19 #include <linux/mutex.h>
20 #include <linux/rcupdate.h>
21 #include <linux/poll.h>
22 #include <linux/file.h>
23 #include <linux/highmem.h>
24 #include <linux/slab.h>
25 #include <linux/kthread.h>
26 #include <linux/cgroup.h>
28 #include <linux/net.h>
29 #include <linux/if_packet.h>
30 #include <linux/if_arp.h>
37 VHOST_MEMORY_MAX_NREGIONS = 64,
38 VHOST_MEMORY_F_LOG = 0x1,
41 static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh,
44 struct vhost_poll *poll;
45 poll = container_of(pt, struct vhost_poll, table);
48 add_wait_queue(wqh, &poll->wait);
51 static int vhost_poll_wakeup(wait_queue_t *wait, unsigned mode, int sync,
54 struct vhost_poll *poll = container_of(wait, struct vhost_poll, wait);
56 if (!((unsigned long)key & poll->mask))
59 vhost_poll_queue(poll);
63 static void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn)
65 INIT_LIST_HEAD(&work->node);
67 init_waitqueue_head(&work->done);
69 work->queue_seq = work->done_seq = 0;
72 /* Init poll structure */
73 void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
74 unsigned long mask, struct vhost_dev *dev)
76 init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup);
77 init_poll_funcptr(&poll->table, vhost_poll_func);
81 vhost_work_init(&poll->work, fn);
84 /* Start polling a file. We add ourselves to file's wait queue. The caller must
85 * keep a reference to a file until after vhost_poll_stop is called. */
86 void vhost_poll_start(struct vhost_poll *poll, struct file *file)
89 mask = file->f_op->poll(file, &poll->table);
91 vhost_poll_wakeup(&poll->wait, 0, 0, (void *)mask);
94 /* Stop polling a file. After this function returns, it becomes safe to drop the
95 * file reference. You must also flush afterwards. */
96 void vhost_poll_stop(struct vhost_poll *poll)
98 remove_wait_queue(poll->wqh, &poll->wait);
101 static void vhost_work_flush(struct vhost_dev *dev, struct vhost_work *work)
107 spin_lock_irq(&dev->work_lock);
108 seq = work->queue_seq;
110 spin_unlock_irq(&dev->work_lock);
111 wait_event(work->done, ({
112 spin_lock_irq(&dev->work_lock);
113 left = seq - work->done_seq <= 0;
114 spin_unlock_irq(&dev->work_lock);
117 spin_lock_irq(&dev->work_lock);
118 flushing = --work->flushing;
119 spin_unlock_irq(&dev->work_lock);
120 BUG_ON(flushing < 0);
123 /* Flush any work that has been scheduled. When calling this, don't hold any
124 * locks that are also used by the callback. */
125 void vhost_poll_flush(struct vhost_poll *poll)
127 vhost_work_flush(poll->dev, &poll->work);
130 static inline void vhost_work_queue(struct vhost_dev *dev,
131 struct vhost_work *work)
135 spin_lock_irqsave(&dev->work_lock, flags);
136 if (list_empty(&work->node)) {
137 list_add_tail(&work->node, &dev->work_list);
139 wake_up_process(dev->worker);
141 spin_unlock_irqrestore(&dev->work_lock, flags);
144 void vhost_poll_queue(struct vhost_poll *poll)
146 vhost_work_queue(poll->dev, &poll->work);
149 static void vhost_vq_reset(struct vhost_dev *dev,
150 struct vhost_virtqueue *vq)
156 vq->last_avail_idx = 0;
158 vq->last_used_idx = 0;
161 vq->log_used = false;
162 vq->log_addr = -1ull;
165 vq->private_data = NULL;
167 vq->error_ctx = NULL;
175 static int vhost_worker(void *data)
177 struct vhost_dev *dev = data;
178 struct vhost_work *work = NULL;
179 unsigned uninitialized_var(seq);
182 /* mb paired w/ kthread_stop */
183 set_current_state(TASK_INTERRUPTIBLE);
185 spin_lock_irq(&dev->work_lock);
187 work->done_seq = seq;
189 wake_up_all(&work->done);
192 if (kthread_should_stop()) {
193 spin_unlock_irq(&dev->work_lock);
194 __set_current_state(TASK_RUNNING);
197 if (!list_empty(&dev->work_list)) {
198 work = list_first_entry(&dev->work_list,
199 struct vhost_work, node);
200 list_del_init(&work->node);
201 seq = work->queue_seq;
204 spin_unlock_irq(&dev->work_lock);
207 __set_current_state(TASK_RUNNING);
215 long vhost_dev_init(struct vhost_dev *dev,
216 struct vhost_virtqueue *vqs, int nvqs)
222 mutex_init(&dev->mutex);
224 dev->log_file = NULL;
227 spin_lock_init(&dev->work_lock);
228 INIT_LIST_HEAD(&dev->work_list);
231 for (i = 0; i < dev->nvqs; ++i) {
232 dev->vqs[i].dev = dev;
233 mutex_init(&dev->vqs[i].mutex);
234 vhost_vq_reset(dev, dev->vqs + i);
235 if (dev->vqs[i].handle_kick)
236 vhost_poll_init(&dev->vqs[i].poll,
237 dev->vqs[i].handle_kick, POLLIN, dev);
243 /* Caller should have device mutex */
244 long vhost_dev_check_owner(struct vhost_dev *dev)
246 /* Are you the owner? If not, I don't think you mean to do that */
247 return dev->mm == current->mm ? 0 : -EPERM;
250 struct vhost_attach_cgroups_struct {
251 struct vhost_work work;
252 struct task_struct *owner;
256 static void vhost_attach_cgroups_work(struct vhost_work *work)
258 struct vhost_attach_cgroups_struct *s;
259 s = container_of(work, struct vhost_attach_cgroups_struct, work);
260 s->ret = cgroup_attach_task_all(s->owner, current);
263 static int vhost_attach_cgroups(struct vhost_dev *dev)
265 struct vhost_attach_cgroups_struct attach;
266 attach.owner = current;
267 vhost_work_init(&attach.work, vhost_attach_cgroups_work);
268 vhost_work_queue(dev, &attach.work);
269 vhost_work_flush(dev, &attach.work);
273 /* Caller should have device mutex */
274 static long vhost_dev_set_owner(struct vhost_dev *dev)
276 struct task_struct *worker;
278 /* Is there an owner already? */
283 /* No owner, become one */
284 dev->mm = get_task_mm(current);
285 worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid);
286 if (IS_ERR(worker)) {
287 err = PTR_ERR(worker);
291 dev->worker = worker;
292 wake_up_process(worker); /* avoid contributing to loadavg */
294 err = vhost_attach_cgroups(dev);
300 kthread_stop(worker);
310 /* Caller should have device mutex */
311 long vhost_dev_reset_owner(struct vhost_dev *dev)
313 struct vhost_memory *memory;
315 /* Restore memory to default empty mapping. */
316 memory = kmalloc(offsetof(struct vhost_memory, regions), GFP_KERNEL);
320 vhost_dev_cleanup(dev);
322 memory->nregions = 0;
323 dev->memory = memory;
327 /* Caller should have device mutex */
328 void vhost_dev_cleanup(struct vhost_dev *dev)
331 for (i = 0; i < dev->nvqs; ++i) {
332 if (dev->vqs[i].kick && dev->vqs[i].handle_kick) {
333 vhost_poll_stop(&dev->vqs[i].poll);
334 vhost_poll_flush(&dev->vqs[i].poll);
336 if (dev->vqs[i].error_ctx)
337 eventfd_ctx_put(dev->vqs[i].error_ctx);
338 if (dev->vqs[i].error)
339 fput(dev->vqs[i].error);
340 if (dev->vqs[i].kick)
341 fput(dev->vqs[i].kick);
342 if (dev->vqs[i].call_ctx)
343 eventfd_ctx_put(dev->vqs[i].call_ctx);
344 if (dev->vqs[i].call)
345 fput(dev->vqs[i].call);
346 vhost_vq_reset(dev, dev->vqs + i);
349 eventfd_ctx_put(dev->log_ctx);
353 dev->log_file = NULL;
354 /* No one will access memory at this point */
361 WARN_ON(!list_empty(&dev->work_list));
363 kthread_stop(dev->worker);
368 static int log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
370 u64 a = addr / VHOST_PAGE_SIZE / 8;
371 /* Make sure 64 bit math will not overflow. */
372 if (a > ULONG_MAX - (unsigned long)log_base ||
373 a + (unsigned long)log_base > ULONG_MAX)
376 return access_ok(VERIFY_WRITE, log_base + a,
377 (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8);
380 /* Caller should have vq mutex and device mutex. */
381 static int vq_memory_access_ok(void __user *log_base, struct vhost_memory *mem,
389 for (i = 0; i < mem->nregions; ++i) {
390 struct vhost_memory_region *m = mem->regions + i;
391 unsigned long a = m->userspace_addr;
392 if (m->memory_size > ULONG_MAX)
394 else if (!access_ok(VERIFY_WRITE, (void __user *)a,
397 else if (log_all && !log_access_ok(log_base,
405 /* Can we switch to this memory table? */
406 /* Caller should have device mutex but not vq mutex */
407 static int memory_access_ok(struct vhost_dev *d, struct vhost_memory *mem,
411 for (i = 0; i < d->nvqs; ++i) {
413 mutex_lock(&d->vqs[i].mutex);
414 /* If ring is inactive, will check when it's enabled. */
415 if (d->vqs[i].private_data)
416 ok = vq_memory_access_ok(d->vqs[i].log_base, mem,
420 mutex_unlock(&d->vqs[i].mutex);
427 static int vq_access_ok(unsigned int num,
428 struct vring_desc __user *desc,
429 struct vring_avail __user *avail,
430 struct vring_used __user *used)
432 return access_ok(VERIFY_READ, desc, num * sizeof *desc) &&
433 access_ok(VERIFY_READ, avail,
434 sizeof *avail + num * sizeof *avail->ring) &&
435 access_ok(VERIFY_WRITE, used,
436 sizeof *used + num * sizeof *used->ring);
439 /* Can we log writes? */
440 /* Caller should have device mutex but not vq mutex */
441 int vhost_log_access_ok(struct vhost_dev *dev)
443 return memory_access_ok(dev, dev->memory, 1);
446 /* Verify access for write logging. */
447 /* Caller should have vq mutex and device mutex */
448 static int vq_log_access_ok(struct vhost_virtqueue *vq, void __user *log_base)
450 return vq_memory_access_ok(log_base, vq->dev->memory,
451 vhost_has_feature(vq->dev, VHOST_F_LOG_ALL)) &&
452 (!vq->log_used || log_access_ok(log_base, vq->log_addr,
454 vq->num * sizeof *vq->used->ring));
457 /* Can we start vq? */
458 /* Caller should have vq mutex and device mutex */
459 int vhost_vq_access_ok(struct vhost_virtqueue *vq)
461 return vq_access_ok(vq->num, vq->desc, vq->avail, vq->used) &&
462 vq_log_access_ok(vq, vq->log_base);
465 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
467 struct vhost_memory mem, *newmem, *oldmem;
468 unsigned long size = offsetof(struct vhost_memory, regions);
469 if (copy_from_user(&mem, m, size))
473 if (mem.nregions > VHOST_MEMORY_MAX_NREGIONS)
475 newmem = kmalloc(size + mem.nregions * sizeof *m->regions, GFP_KERNEL);
479 memcpy(newmem, &mem, size);
480 if (copy_from_user(newmem->regions, m->regions,
481 mem.nregions * sizeof *m->regions)) {
486 if (!memory_access_ok(d, newmem, vhost_has_feature(d, VHOST_F_LOG_ALL))) {
491 rcu_assign_pointer(d->memory, newmem);
497 static int init_used(struct vhost_virtqueue *vq,
498 struct vring_used __user *used)
500 int r = put_user(vq->used_flags, &used->flags);
503 return get_user(vq->last_used_idx, &used->idx);
506 static long vhost_set_vring(struct vhost_dev *d, int ioctl, void __user *argp)
508 struct file *eventfp, *filep = NULL,
509 *pollstart = NULL, *pollstop = NULL;
510 struct eventfd_ctx *ctx = NULL;
511 u32 __user *idxp = argp;
512 struct vhost_virtqueue *vq;
513 struct vhost_vring_state s;
514 struct vhost_vring_file f;
515 struct vhost_vring_addr a;
519 r = get_user(idx, idxp);
527 mutex_lock(&vq->mutex);
530 case VHOST_SET_VRING_NUM:
531 /* Resizing ring with an active backend?
532 * You don't want to do that. */
533 if (vq->private_data) {
537 if (copy_from_user(&s, argp, sizeof s)) {
541 if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) {
547 case VHOST_SET_VRING_BASE:
548 /* Moving base with an active backend?
549 * You don't want to do that. */
550 if (vq->private_data) {
554 if (copy_from_user(&s, argp, sizeof s)) {
558 if (s.num > 0xffff) {
562 vq->last_avail_idx = s.num;
563 /* Forget the cached index value. */
564 vq->avail_idx = vq->last_avail_idx;
566 case VHOST_GET_VRING_BASE:
568 s.num = vq->last_avail_idx;
569 if (copy_to_user(argp, &s, sizeof s))
572 case VHOST_SET_VRING_ADDR:
573 if (copy_from_user(&a, argp, sizeof a)) {
577 if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) {
581 /* For 32bit, verify that the top 32bits of the user
582 data are set to zero. */
583 if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr ||
584 (u64)(unsigned long)a.used_user_addr != a.used_user_addr ||
585 (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) {
589 if ((a.avail_user_addr & (sizeof *vq->avail->ring - 1)) ||
590 (a.used_user_addr & (sizeof *vq->used->ring - 1)) ||
591 (a.log_guest_addr & (sizeof *vq->used->ring - 1))) {
596 /* We only verify access here if backend is configured.
597 * If it is not, we don't as size might not have been setup.
598 * We will verify when backend is configured. */
599 if (vq->private_data) {
600 if (!vq_access_ok(vq->num,
601 (void __user *)(unsigned long)a.desc_user_addr,
602 (void __user *)(unsigned long)a.avail_user_addr,
603 (void __user *)(unsigned long)a.used_user_addr)) {
608 /* Also validate log access for used ring if enabled. */
609 if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) &&
610 !log_access_ok(vq->log_base, a.log_guest_addr,
612 vq->num * sizeof *vq->used->ring)) {
618 r = init_used(vq, (struct vring_used __user *)(unsigned long)
622 vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
623 vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
624 vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
625 vq->log_addr = a.log_guest_addr;
626 vq->used = (void __user *)(unsigned long)a.used_user_addr;
628 case VHOST_SET_VRING_KICK:
629 if (copy_from_user(&f, argp, sizeof f)) {
633 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
634 if (IS_ERR(eventfp)) {
635 r = PTR_ERR(eventfp);
638 if (eventfp != vq->kick) {
639 pollstop = filep = vq->kick;
640 pollstart = vq->kick = eventfp;
644 case VHOST_SET_VRING_CALL:
645 if (copy_from_user(&f, argp, sizeof f)) {
649 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
650 if (IS_ERR(eventfp)) {
651 r = PTR_ERR(eventfp);
654 if (eventfp != vq->call) {
658 vq->call_ctx = eventfp ?
659 eventfd_ctx_fileget(eventfp) : NULL;
663 case VHOST_SET_VRING_ERR:
664 if (copy_from_user(&f, argp, sizeof f)) {
668 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
669 if (IS_ERR(eventfp)) {
670 r = PTR_ERR(eventfp);
673 if (eventfp != vq->error) {
677 vq->error_ctx = eventfp ?
678 eventfd_ctx_fileget(eventfp) : NULL;
686 if (pollstop && vq->handle_kick)
687 vhost_poll_stop(&vq->poll);
690 eventfd_ctx_put(ctx);
694 if (pollstart && vq->handle_kick)
695 vhost_poll_start(&vq->poll, vq->kick);
697 mutex_unlock(&vq->mutex);
699 if (pollstop && vq->handle_kick)
700 vhost_poll_flush(&vq->poll);
704 /* Caller must have device mutex */
705 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, unsigned long arg)
707 void __user *argp = (void __user *)arg;
708 struct file *eventfp, *filep = NULL;
709 struct eventfd_ctx *ctx = NULL;
714 /* If you are not the owner, you can become one */
715 if (ioctl == VHOST_SET_OWNER) {
716 r = vhost_dev_set_owner(d);
720 /* You must be the owner to do anything else */
721 r = vhost_dev_check_owner(d);
726 case VHOST_SET_MEM_TABLE:
727 r = vhost_set_memory(d, argp);
729 case VHOST_SET_LOG_BASE:
730 if (copy_from_user(&p, argp, sizeof p)) {
734 if ((u64)(unsigned long)p != p) {
738 for (i = 0; i < d->nvqs; ++i) {
739 struct vhost_virtqueue *vq;
740 void __user *base = (void __user *)(unsigned long)p;
742 mutex_lock(&vq->mutex);
743 /* If ring is inactive, will check when it's enabled. */
744 if (vq->private_data && !vq_log_access_ok(vq, base))
748 mutex_unlock(&vq->mutex);
751 case VHOST_SET_LOG_FD:
752 r = get_user(fd, (int __user *)argp);
755 eventfp = fd == -1 ? NULL : eventfd_fget(fd);
756 if (IS_ERR(eventfp)) {
757 r = PTR_ERR(eventfp);
760 if (eventfp != d->log_file) {
763 d->log_ctx = eventfp ?
764 eventfd_ctx_fileget(eventfp) : NULL;
767 for (i = 0; i < d->nvqs; ++i) {
768 mutex_lock(&d->vqs[i].mutex);
769 d->vqs[i].log_ctx = d->log_ctx;
770 mutex_unlock(&d->vqs[i].mutex);
773 eventfd_ctx_put(ctx);
778 r = vhost_set_vring(d, ioctl, argp);
785 static const struct vhost_memory_region *find_region(struct vhost_memory *mem,
786 __u64 addr, __u32 len)
788 struct vhost_memory_region *reg;
790 /* linear search is not brilliant, but we really have on the order of 6
791 * regions in practice */
792 for (i = 0; i < mem->nregions; ++i) {
793 reg = mem->regions + i;
794 if (reg->guest_phys_addr <= addr &&
795 reg->guest_phys_addr + reg->memory_size - 1 >= addr)
801 /* TODO: This is really inefficient. We need something like get_user()
802 * (instruction directly accesses the data, with an exception table entry
803 * returning -EFAULT). See Documentation/x86/exception-tables.txt.
805 static int set_bit_to_user(int nr, void __user *addr)
807 unsigned long log = (unsigned long)addr;
810 int bit = nr + (log % PAGE_SIZE) * 8;
812 r = get_user_pages_fast(log, 1, 1, &page);
816 base = kmap_atomic(page, KM_USER0);
818 kunmap_atomic(base, KM_USER0);
819 set_page_dirty_lock(page);
824 static int log_write(void __user *log_base,
825 u64 write_address, u64 write_length)
830 write_address /= VHOST_PAGE_SIZE;
832 u64 base = (u64)(unsigned long)log_base;
833 u64 log = base + write_address / 8;
834 int bit = write_address % 8;
835 if ((u64)(unsigned long)log != log)
837 r = set_bit_to_user(bit, (void __user *)(unsigned long)log);
840 if (write_length <= VHOST_PAGE_SIZE)
842 write_length -= VHOST_PAGE_SIZE;
843 write_address += VHOST_PAGE_SIZE;
848 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
849 unsigned int log_num, u64 len)
853 /* Make sure data written is seen before log. */
855 for (i = 0; i < log_num; ++i) {
856 u64 l = min(log[i].len, len);
857 r = log_write(vq->log_base, log[i].addr, l);
863 eventfd_signal(vq->log_ctx, 1);
867 /* Length written exceeds what we have stored. This is a bug. */
872 static int translate_desc(struct vhost_dev *dev, u64 addr, u32 len,
873 struct iovec iov[], int iov_size)
875 const struct vhost_memory_region *reg;
876 struct vhost_memory *mem;
883 mem = rcu_dereference(dev->memory);
884 while ((u64)len > s) {
886 if (unlikely(ret >= iov_size)) {
890 reg = find_region(mem, addr, len);
891 if (unlikely(!reg)) {
896 size = reg->memory_size - addr + reg->guest_phys_addr;
897 _iov->iov_len = min((u64)len, size);
898 _iov->iov_base = (void __user *)(unsigned long)
899 (reg->userspace_addr + addr - reg->guest_phys_addr);
909 /* Each buffer in the virtqueues is actually a chain of descriptors. This
910 * function returns the next descriptor in the chain,
911 * or -1U if we're at the end. */
912 static unsigned next_desc(struct vring_desc *desc)
916 /* If this descriptor says it doesn't chain, we're done. */
917 if (!(desc->flags & VRING_DESC_F_NEXT))
920 /* Check they're not leading us off end of descriptors. */
922 /* Make sure compiler knows to grab that: we don't want it changing! */
923 /* We will use the result as an index in an array, so most
924 * architectures only need a compiler barrier here. */
925 read_barrier_depends();
930 static int get_indirect(struct vhost_dev *dev, struct vhost_virtqueue *vq,
931 struct iovec iov[], unsigned int iov_size,
932 unsigned int *out_num, unsigned int *in_num,
933 struct vhost_log *log, unsigned int *log_num,
934 struct vring_desc *indirect)
936 struct vring_desc desc;
937 unsigned int i = 0, count, found = 0;
941 if (unlikely(indirect->len % sizeof desc)) {
942 vq_err(vq, "Invalid length in indirect descriptor: "
943 "len 0x%llx not multiple of 0x%zx\n",
944 (unsigned long long)indirect->len,
949 ret = translate_desc(dev, indirect->addr, indirect->len, vq->indirect,
950 ARRAY_SIZE(vq->indirect));
951 if (unlikely(ret < 0)) {
952 vq_err(vq, "Translation failure %d in indirect.\n", ret);
956 /* We will use the result as an address to read from, so most
957 * architectures only need a compiler barrier here. */
958 read_barrier_depends();
960 count = indirect->len / sizeof desc;
961 /* Buffers are chained via a 16 bit next field, so
962 * we can have at most 2^16 of these. */
963 if (unlikely(count > USHRT_MAX + 1)) {
964 vq_err(vq, "Indirect buffer length too big: %d\n",
970 unsigned iov_count = *in_num + *out_num;
971 if (unlikely(++found > count)) {
972 vq_err(vq, "Loop detected: last one at %u "
973 "indirect size %u\n",
977 if (unlikely(memcpy_fromiovec((unsigned char *)&desc, vq->indirect,
979 vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n",
980 i, (size_t)indirect->addr + i * sizeof desc);
983 if (unlikely(desc.flags & VRING_DESC_F_INDIRECT)) {
984 vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n",
985 i, (size_t)indirect->addr + i * sizeof desc);
989 ret = translate_desc(dev, desc.addr, desc.len, iov + iov_count,
990 iov_size - iov_count);
991 if (unlikely(ret < 0)) {
992 vq_err(vq, "Translation failure %d indirect idx %d\n",
996 /* If this is an input descriptor, increment that count. */
997 if (desc.flags & VRING_DESC_F_WRITE) {
1000 log[*log_num].addr = desc.addr;
1001 log[*log_num].len = desc.len;
1005 /* If it's an output descriptor, they're all supposed
1006 * to come before any input descriptors. */
1007 if (unlikely(*in_num)) {
1008 vq_err(vq, "Indirect descriptor "
1009 "has out after in: idx %d\n", i);
1014 } while ((i = next_desc(&desc)) != -1);
1018 /* This looks in the virtqueue and for the first available buffer, and converts
1019 * it to an iovec for convenient access. Since descriptors consist of some
1020 * number of output then some number of input descriptors, it's actually two
1021 * iovecs, but we pack them into one and note how many of each there were.
1023 * This function returns the descriptor number found, or vq->num (which is
1024 * never a valid descriptor number) if none was found. A negative code is
1025 * returned on error. */
1026 int vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq,
1027 struct iovec iov[], unsigned int iov_size,
1028 unsigned int *out_num, unsigned int *in_num,
1029 struct vhost_log *log, unsigned int *log_num)
1031 struct vring_desc desc;
1032 unsigned int i, head, found = 0;
1036 /* Check it isn't doing very strange things with descriptor numbers. */
1037 last_avail_idx = vq->last_avail_idx;
1038 if (unlikely(get_user(vq->avail_idx, &vq->avail->idx))) {
1039 vq_err(vq, "Failed to access avail idx at %p\n",
1044 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
1045 vq_err(vq, "Guest moved used index from %u to %u",
1046 last_avail_idx, vq->avail_idx);
1050 /* If there's nothing new since last we looked, return invalid. */
1051 if (vq->avail_idx == last_avail_idx)
1054 /* Only get avail ring entries after they have been exposed by guest. */
1057 /* Grab the next descriptor number they're advertising, and increment
1058 * the index we've seen. */
1059 if (unlikely(get_user(head,
1060 &vq->avail->ring[last_avail_idx % vq->num]))) {
1061 vq_err(vq, "Failed to read head: idx %d address %p\n",
1063 &vq->avail->ring[last_avail_idx % vq->num]);
1067 /* If their number is silly, that's an error. */
1068 if (unlikely(head >= vq->num)) {
1069 vq_err(vq, "Guest says index %u > %u is available",
1074 /* When we start there are none of either input nor output. */
1075 *out_num = *in_num = 0;
1081 unsigned iov_count = *in_num + *out_num;
1082 if (unlikely(i >= vq->num)) {
1083 vq_err(vq, "Desc index is %u > %u, head = %u",
1087 if (unlikely(++found > vq->num)) {
1088 vq_err(vq, "Loop detected: last one at %u "
1089 "vq size %u head %u\n",
1093 ret = copy_from_user(&desc, vq->desc + i, sizeof desc);
1094 if (unlikely(ret)) {
1095 vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
1099 if (desc.flags & VRING_DESC_F_INDIRECT) {
1100 ret = get_indirect(dev, vq, iov, iov_size,
1102 log, log_num, &desc);
1103 if (unlikely(ret < 0)) {
1104 vq_err(vq, "Failure detected "
1105 "in indirect descriptor at idx %d\n", i);
1111 ret = translate_desc(dev, desc.addr, desc.len, iov + iov_count,
1112 iov_size - iov_count);
1113 if (unlikely(ret < 0)) {
1114 vq_err(vq, "Translation failure %d descriptor idx %d\n",
1118 if (desc.flags & VRING_DESC_F_WRITE) {
1119 /* If this is an input descriptor,
1120 * increment that count. */
1122 if (unlikely(log)) {
1123 log[*log_num].addr = desc.addr;
1124 log[*log_num].len = desc.len;
1128 /* If it's an output descriptor, they're all supposed
1129 * to come before any input descriptors. */
1130 if (unlikely(*in_num)) {
1131 vq_err(vq, "Descriptor has out after in: "
1137 } while ((i = next_desc(&desc)) != -1);
1139 /* On success, increment avail index. */
1140 vq->last_avail_idx++;
1144 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
1145 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
1147 vq->last_avail_idx -= n;
1150 /* After we've used one of their buffers, we tell them about it. We'll then
1151 * want to notify the guest, using eventfd. */
1152 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
1154 struct vring_used_elem __user *used;
1156 /* The virtqueue contains a ring of used buffers. Get a pointer to the
1157 * next entry in that used ring. */
1158 used = &vq->used->ring[vq->last_used_idx % vq->num];
1159 if (put_user(head, &used->id)) {
1160 vq_err(vq, "Failed to write used id");
1163 if (put_user(len, &used->len)) {
1164 vq_err(vq, "Failed to write used len");
1167 /* Make sure buffer is written before we update index. */
1169 if (put_user(vq->last_used_idx + 1, &vq->used->idx)) {
1170 vq_err(vq, "Failed to increment used idx");
1173 if (unlikely(vq->log_used)) {
1174 /* Make sure data is seen before log. */
1176 /* Log used ring entry write. */
1177 log_write(vq->log_base,
1179 ((void __user *)used - (void __user *)vq->used),
1181 /* Log used index update. */
1182 log_write(vq->log_base,
1183 vq->log_addr + offsetof(struct vring_used, idx),
1184 sizeof vq->used->idx);
1186 eventfd_signal(vq->log_ctx, 1);
1188 vq->last_used_idx++;
1192 static int __vhost_add_used_n(struct vhost_virtqueue *vq,
1193 struct vring_used_elem *heads,
1196 struct vring_used_elem __user *used;
1199 start = vq->last_used_idx % vq->num;
1200 used = vq->used->ring + start;
1201 if (copy_to_user(used, heads, count * sizeof *used)) {
1202 vq_err(vq, "Failed to write used");
1205 if (unlikely(vq->log_used)) {
1206 /* Make sure data is seen before log. */
1208 /* Log used ring entry write. */
1209 log_write(vq->log_base,
1211 ((void __user *)used - (void __user *)vq->used),
1212 count * sizeof *used);
1214 vq->last_used_idx += count;
1218 /* After we've used one of their buffers, we tell them about it. We'll then
1219 * want to notify the guest, using eventfd. */
1220 int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
1225 start = vq->last_used_idx % vq->num;
1226 n = vq->num - start;
1228 r = __vhost_add_used_n(vq, heads, n);
1234 r = __vhost_add_used_n(vq, heads, count);
1236 /* Make sure buffer is written before we update index. */
1238 if (put_user(vq->last_used_idx, &vq->used->idx)) {
1239 vq_err(vq, "Failed to increment used idx");
1242 if (unlikely(vq->log_used)) {
1243 /* Log used index update. */
1244 log_write(vq->log_base,
1245 vq->log_addr + offsetof(struct vring_used, idx),
1246 sizeof vq->used->idx);
1248 eventfd_signal(vq->log_ctx, 1);
1253 /* This actually signals the guest, using eventfd. */
1254 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1257 /* Flush out used index updates. This is paired
1258 * with the barrier that the Guest executes when enabling
1262 if (get_user(flags, &vq->avail->flags)) {
1263 vq_err(vq, "Failed to get flags");
1267 /* If they don't want an interrupt, don't signal, unless empty. */
1268 if ((flags & VRING_AVAIL_F_NO_INTERRUPT) &&
1269 (vq->avail_idx != vq->last_avail_idx ||
1270 !vhost_has_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY)))
1273 /* Signal the Guest tell them we used something up. */
1275 eventfd_signal(vq->call_ctx, 1);
1278 /* And here's the combo meal deal. Supersize me! */
1279 void vhost_add_used_and_signal(struct vhost_dev *dev,
1280 struct vhost_virtqueue *vq,
1281 unsigned int head, int len)
1283 vhost_add_used(vq, head, len);
1284 vhost_signal(dev, vq);
1287 /* multi-buffer version of vhost_add_used_and_signal */
1288 void vhost_add_used_and_signal_n(struct vhost_dev *dev,
1289 struct vhost_virtqueue *vq,
1290 struct vring_used_elem *heads, unsigned count)
1292 vhost_add_used_n(vq, heads, count);
1293 vhost_signal(dev, vq);
1296 /* OK, now we need to know about added descriptors. */
1297 bool vhost_enable_notify(struct vhost_virtqueue *vq)
1301 if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
1303 vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
1304 r = put_user(vq->used_flags, &vq->used->flags);
1306 vq_err(vq, "Failed to enable notification at %p: %d\n",
1307 &vq->used->flags, r);
1310 /* They could have slipped one in as we were doing that: make
1311 * sure it's written, then check again. */
1313 r = get_user(avail_idx, &vq->avail->idx);
1315 vq_err(vq, "Failed to check avail idx at %p: %d\n",
1316 &vq->avail->idx, r);
1320 return avail_idx != vq->avail_idx;
1323 /* We don't need to be notified again. */
1324 void vhost_disable_notify(struct vhost_virtqueue *vq)
1327 if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
1329 vq->used_flags |= VRING_USED_F_NO_NOTIFY;
1330 r = put_user(vq->used_flags, &vq->used->flags);
1332 vq_err(vq, "Failed to enable notification at %p: %d\n",
1333 &vq->used->flags, r);