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/kthread.h>
26 #include <linux/cgroup.h>
27 #include <linux/module.h>
32 VHOST_MEMORY_MAX_NREGIONS = 64,
33 VHOST_MEMORY_F_LOG = 0x1,
36 #define vhost_used_event(vq) ((u16 __user *)&vq->avail->ring[vq->num])
37 #define vhost_avail_event(vq) ((u16 __user *)&vq->used->ring[vq->num])
39 static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh,
42 struct vhost_poll *poll;
44 poll = container_of(pt, struct vhost_poll, table);
46 add_wait_queue(wqh, &poll->wait);
49 static int vhost_poll_wakeup(wait_queue_t *wait, unsigned mode, int sync,
52 struct vhost_poll *poll = container_of(wait, struct vhost_poll, wait);
54 if (!((unsigned long)key & poll->mask))
57 vhost_poll_queue(poll);
61 void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn)
63 INIT_LIST_HEAD(&work->node);
65 init_waitqueue_head(&work->done);
67 work->queue_seq = work->done_seq = 0;
69 EXPORT_SYMBOL_GPL(vhost_work_init);
71 /* Init poll structure */
72 void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
73 unsigned long mask, struct vhost_dev *dev)
75 init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup);
76 init_poll_funcptr(&poll->table, vhost_poll_func);
81 vhost_work_init(&poll->work, fn);
83 EXPORT_SYMBOL_GPL(vhost_poll_init);
85 /* Start polling a file. We add ourselves to file's wait queue. The caller must
86 * keep a reference to a file until after vhost_poll_stop is called. */
87 int vhost_poll_start(struct vhost_poll *poll, struct file *file)
95 mask = file->f_op->poll(file, &poll->table);
97 vhost_poll_wakeup(&poll->wait, 0, 0, (void *)mask);
100 remove_wait_queue(poll->wqh, &poll->wait);
106 EXPORT_SYMBOL_GPL(vhost_poll_start);
108 /* Stop polling a file. After this function returns, it becomes safe to drop the
109 * file reference. You must also flush afterwards. */
110 void vhost_poll_stop(struct vhost_poll *poll)
113 remove_wait_queue(poll->wqh, &poll->wait);
117 EXPORT_SYMBOL_GPL(vhost_poll_stop);
119 static bool vhost_work_seq_done(struct vhost_dev *dev, struct vhost_work *work,
124 spin_lock_irq(&dev->work_lock);
125 left = seq - work->done_seq;
126 spin_unlock_irq(&dev->work_lock);
130 void vhost_work_flush(struct vhost_dev *dev, struct vhost_work *work)
135 spin_lock_irq(&dev->work_lock);
136 seq = work->queue_seq;
138 spin_unlock_irq(&dev->work_lock);
139 wait_event(work->done, vhost_work_seq_done(dev, work, seq));
140 spin_lock_irq(&dev->work_lock);
141 flushing = --work->flushing;
142 spin_unlock_irq(&dev->work_lock);
143 BUG_ON(flushing < 0);
145 EXPORT_SYMBOL_GPL(vhost_work_flush);
147 /* Flush any work that has been scheduled. When calling this, don't hold any
148 * locks that are also used by the callback. */
149 void vhost_poll_flush(struct vhost_poll *poll)
151 vhost_work_flush(poll->dev, &poll->work);
153 EXPORT_SYMBOL_GPL(vhost_poll_flush);
155 void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work)
159 spin_lock_irqsave(&dev->work_lock, flags);
160 if (list_empty(&work->node)) {
161 list_add_tail(&work->node, &dev->work_list);
163 spin_unlock_irqrestore(&dev->work_lock, flags);
164 wake_up_process(dev->worker);
166 spin_unlock_irqrestore(&dev->work_lock, flags);
169 EXPORT_SYMBOL_GPL(vhost_work_queue);
171 void vhost_poll_queue(struct vhost_poll *poll)
173 vhost_work_queue(poll->dev, &poll->work);
175 EXPORT_SYMBOL_GPL(vhost_poll_queue);
177 static void vhost_vq_reset(struct vhost_dev *dev,
178 struct vhost_virtqueue *vq)
184 vq->last_avail_idx = 0;
186 vq->last_used_idx = 0;
187 vq->signalled_used = 0;
188 vq->signalled_used_valid = false;
190 vq->log_used = false;
191 vq->log_addr = -1ull;
192 vq->private_data = NULL;
193 vq->acked_features = 0;
195 vq->error_ctx = NULL;
204 static int vhost_worker(void *data)
206 struct vhost_dev *dev = data;
207 struct vhost_work *work = NULL;
208 unsigned uninitialized_var(seq);
209 mm_segment_t oldfs = get_fs();
215 /* mb paired w/ kthread_stop */
216 set_current_state(TASK_INTERRUPTIBLE);
218 spin_lock_irq(&dev->work_lock);
220 work->done_seq = seq;
222 wake_up_all(&work->done);
225 if (kthread_should_stop()) {
226 spin_unlock_irq(&dev->work_lock);
227 __set_current_state(TASK_RUNNING);
230 if (!list_empty(&dev->work_list)) {
231 work = list_first_entry(&dev->work_list,
232 struct vhost_work, node);
233 list_del_init(&work->node);
234 seq = work->queue_seq;
237 spin_unlock_irq(&dev->work_lock);
240 __set_current_state(TASK_RUNNING);
253 static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq)
263 /* Helper to allocate iovec buffers for all vqs. */
264 static long vhost_dev_alloc_iovecs(struct vhost_dev *dev)
266 struct vhost_virtqueue *vq;
269 for (i = 0; i < dev->nvqs; ++i) {
271 vq->indirect = kmalloc(sizeof *vq->indirect * UIO_MAXIOV,
273 vq->log = kmalloc(sizeof *vq->log * UIO_MAXIOV, GFP_KERNEL);
274 vq->heads = kmalloc(sizeof *vq->heads * UIO_MAXIOV, GFP_KERNEL);
275 if (!vq->indirect || !vq->log || !vq->heads)
282 vhost_vq_free_iovecs(dev->vqs[i]);
286 static void vhost_dev_free_iovecs(struct vhost_dev *dev)
290 for (i = 0; i < dev->nvqs; ++i)
291 vhost_vq_free_iovecs(dev->vqs[i]);
294 void vhost_dev_init(struct vhost_dev *dev,
295 struct vhost_virtqueue **vqs, int nvqs)
297 struct vhost_virtqueue *vq;
302 mutex_init(&dev->mutex);
304 dev->log_file = NULL;
307 spin_lock_init(&dev->work_lock);
308 INIT_LIST_HEAD(&dev->work_list);
311 for (i = 0; i < dev->nvqs; ++i) {
317 mutex_init(&vq->mutex);
318 vhost_vq_reset(dev, vq);
320 vhost_poll_init(&vq->poll, vq->handle_kick,
324 EXPORT_SYMBOL_GPL(vhost_dev_init);
326 /* Caller should have device mutex */
327 long vhost_dev_check_owner(struct vhost_dev *dev)
329 /* Are you the owner? If not, I don't think you mean to do that */
330 return dev->mm == current->mm ? 0 : -EPERM;
332 EXPORT_SYMBOL_GPL(vhost_dev_check_owner);
334 struct vhost_attach_cgroups_struct {
335 struct vhost_work work;
336 struct task_struct *owner;
340 static void vhost_attach_cgroups_work(struct vhost_work *work)
342 struct vhost_attach_cgroups_struct *s;
344 s = container_of(work, struct vhost_attach_cgroups_struct, work);
345 s->ret = cgroup_attach_task_all(s->owner, current);
348 static int vhost_attach_cgroups(struct vhost_dev *dev)
350 struct vhost_attach_cgroups_struct attach;
352 attach.owner = current;
353 vhost_work_init(&attach.work, vhost_attach_cgroups_work);
354 vhost_work_queue(dev, &attach.work);
355 vhost_work_flush(dev, &attach.work);
359 /* Caller should have device mutex */
360 bool vhost_dev_has_owner(struct vhost_dev *dev)
364 EXPORT_SYMBOL_GPL(vhost_dev_has_owner);
366 /* Caller should have device mutex */
367 long vhost_dev_set_owner(struct vhost_dev *dev)
369 struct task_struct *worker;
372 /* Is there an owner already? */
373 if (vhost_dev_has_owner(dev)) {
378 /* No owner, become one */
379 dev->mm = get_task_mm(current);
380 worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid);
381 if (IS_ERR(worker)) {
382 err = PTR_ERR(worker);
386 dev->worker = worker;
387 wake_up_process(worker); /* avoid contributing to loadavg */
389 err = vhost_attach_cgroups(dev);
393 err = vhost_dev_alloc_iovecs(dev);
399 kthread_stop(worker);
408 EXPORT_SYMBOL_GPL(vhost_dev_set_owner);
410 struct vhost_memory *vhost_dev_reset_owner_prepare(void)
412 return kmalloc(offsetof(struct vhost_memory, regions), GFP_KERNEL);
414 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner_prepare);
416 /* Caller should have device mutex */
417 void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_memory *memory)
421 vhost_dev_cleanup(dev, true);
423 /* Restore memory to default empty mapping. */
424 memory->nregions = 0;
425 dev->memory = memory;
426 /* We don't need VQ locks below since vhost_dev_cleanup makes sure
427 * VQs aren't running.
429 for (i = 0; i < dev->nvqs; ++i)
430 dev->vqs[i]->memory = memory;
432 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner);
434 void vhost_dev_stop(struct vhost_dev *dev)
438 for (i = 0; i < dev->nvqs; ++i) {
439 if (dev->vqs[i]->kick && dev->vqs[i]->handle_kick) {
440 vhost_poll_stop(&dev->vqs[i]->poll);
441 vhost_poll_flush(&dev->vqs[i]->poll);
445 EXPORT_SYMBOL_GPL(vhost_dev_stop);
447 /* Caller should have device mutex if and only if locked is set */
448 void vhost_dev_cleanup(struct vhost_dev *dev, bool locked)
452 for (i = 0; i < dev->nvqs; ++i) {
453 if (dev->vqs[i]->error_ctx)
454 eventfd_ctx_put(dev->vqs[i]->error_ctx);
455 if (dev->vqs[i]->error)
456 fput(dev->vqs[i]->error);
457 if (dev->vqs[i]->kick)
458 fput(dev->vqs[i]->kick);
459 if (dev->vqs[i]->call_ctx)
460 eventfd_ctx_put(dev->vqs[i]->call_ctx);
461 if (dev->vqs[i]->call)
462 fput(dev->vqs[i]->call);
463 vhost_vq_reset(dev, dev->vqs[i]);
465 vhost_dev_free_iovecs(dev);
467 eventfd_ctx_put(dev->log_ctx);
471 dev->log_file = NULL;
472 /* No one will access memory at this point */
475 WARN_ON(!list_empty(&dev->work_list));
477 kthread_stop(dev->worker);
484 EXPORT_SYMBOL_GPL(vhost_dev_cleanup);
486 static int log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
488 u64 a = addr / VHOST_PAGE_SIZE / 8;
490 /* Make sure 64 bit math will not overflow. */
491 if (a > ULONG_MAX - (unsigned long)log_base ||
492 a + (unsigned long)log_base > ULONG_MAX)
495 return access_ok(VERIFY_WRITE, log_base + a,
496 (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8);
499 /* Caller should have vq mutex and device mutex. */
500 static int vq_memory_access_ok(void __user *log_base, struct vhost_memory *mem,
508 for (i = 0; i < mem->nregions; ++i) {
509 struct vhost_memory_region *m = mem->regions + i;
510 unsigned long a = m->userspace_addr;
511 if (m->memory_size > ULONG_MAX)
513 else if (!access_ok(VERIFY_WRITE, (void __user *)a,
516 else if (log_all && !log_access_ok(log_base,
524 /* Can we switch to this memory table? */
525 /* Caller should have device mutex but not vq mutex */
526 static int memory_access_ok(struct vhost_dev *d, struct vhost_memory *mem,
531 for (i = 0; i < d->nvqs; ++i) {
535 mutex_lock(&d->vqs[i]->mutex);
536 log = log_all || vhost_has_feature(d->vqs[i], VHOST_F_LOG_ALL);
537 /* If ring is inactive, will check when it's enabled. */
538 if (d->vqs[i]->private_data)
539 ok = vq_memory_access_ok(d->vqs[i]->log_base, mem, log);
542 mutex_unlock(&d->vqs[i]->mutex);
549 static int vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
550 struct vring_desc __user *desc,
551 struct vring_avail __user *avail,
552 struct vring_used __user *used)
554 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
555 return access_ok(VERIFY_READ, desc, num * sizeof *desc) &&
556 access_ok(VERIFY_READ, avail,
557 sizeof *avail + num * sizeof *avail->ring + s) &&
558 access_ok(VERIFY_WRITE, used,
559 sizeof *used + num * sizeof *used->ring + s);
562 /* Can we log writes? */
563 /* Caller should have device mutex but not vq mutex */
564 int vhost_log_access_ok(struct vhost_dev *dev)
566 return memory_access_ok(dev, dev->memory, 1);
568 EXPORT_SYMBOL_GPL(vhost_log_access_ok);
570 /* Verify access for write logging. */
571 /* Caller should have vq mutex and device mutex */
572 static int vq_log_access_ok(struct vhost_virtqueue *vq,
573 void __user *log_base)
575 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
577 return vq_memory_access_ok(log_base, vq->memory,
578 vhost_has_feature(vq, VHOST_F_LOG_ALL)) &&
579 (!vq->log_used || log_access_ok(log_base, vq->log_addr,
581 vq->num * sizeof *vq->used->ring + s));
584 /* Can we start vq? */
585 /* Caller should have vq mutex and device mutex */
586 int vhost_vq_access_ok(struct vhost_virtqueue *vq)
588 return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used) &&
589 vq_log_access_ok(vq, vq->log_base);
591 EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
593 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
595 struct vhost_memory mem, *newmem, *oldmem;
596 unsigned long size = offsetof(struct vhost_memory, regions);
599 if (copy_from_user(&mem, m, size))
603 if (mem.nregions > VHOST_MEMORY_MAX_NREGIONS)
605 newmem = kmalloc(size + mem.nregions * sizeof *m->regions, GFP_KERNEL);
609 memcpy(newmem, &mem, size);
610 if (copy_from_user(newmem->regions, m->regions,
611 mem.nregions * sizeof *m->regions)) {
616 if (!memory_access_ok(d, newmem, 0)) {
623 /* All memory accesses are done under some VQ mutex. */
624 for (i = 0; i < d->nvqs; ++i) {
625 mutex_lock(&d->vqs[i]->mutex);
626 d->vqs[i]->memory = newmem;
627 mutex_unlock(&d->vqs[i]->mutex);
633 long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp)
635 struct file *eventfp, *filep = NULL;
636 bool pollstart = false, pollstop = false;
637 struct eventfd_ctx *ctx = NULL;
638 u32 __user *idxp = argp;
639 struct vhost_virtqueue *vq;
640 struct vhost_vring_state s;
641 struct vhost_vring_file f;
642 struct vhost_vring_addr a;
646 r = get_user(idx, idxp);
654 mutex_lock(&vq->mutex);
657 case VHOST_SET_VRING_NUM:
658 /* Resizing ring with an active backend?
659 * You don't want to do that. */
660 if (vq->private_data) {
664 if (copy_from_user(&s, argp, sizeof s)) {
668 if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) {
674 case VHOST_SET_VRING_BASE:
675 /* Moving base with an active backend?
676 * You don't want to do that. */
677 if (vq->private_data) {
681 if (copy_from_user(&s, argp, sizeof s)) {
685 if (s.num > 0xffff) {
689 vq->last_avail_idx = s.num;
690 /* Forget the cached index value. */
691 vq->avail_idx = vq->last_avail_idx;
693 case VHOST_GET_VRING_BASE:
695 s.num = vq->last_avail_idx;
696 if (copy_to_user(argp, &s, sizeof s))
699 case VHOST_SET_VRING_ADDR:
700 if (copy_from_user(&a, argp, sizeof a)) {
704 if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) {
708 /* For 32bit, verify that the top 32bits of the user
709 data are set to zero. */
710 if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr ||
711 (u64)(unsigned long)a.used_user_addr != a.used_user_addr ||
712 (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) {
716 if ((a.avail_user_addr & (sizeof *vq->avail->ring - 1)) ||
717 (a.used_user_addr & (sizeof *vq->used->ring - 1)) ||
718 (a.log_guest_addr & (sizeof *vq->used->ring - 1))) {
723 /* We only verify access here if backend is configured.
724 * If it is not, we don't as size might not have been setup.
725 * We will verify when backend is configured. */
726 if (vq->private_data) {
727 if (!vq_access_ok(vq, vq->num,
728 (void __user *)(unsigned long)a.desc_user_addr,
729 (void __user *)(unsigned long)a.avail_user_addr,
730 (void __user *)(unsigned long)a.used_user_addr)) {
735 /* Also validate log access for used ring if enabled. */
736 if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) &&
737 !log_access_ok(vq->log_base, a.log_guest_addr,
739 vq->num * sizeof *vq->used->ring)) {
745 vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
746 vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
747 vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
748 vq->log_addr = a.log_guest_addr;
749 vq->used = (void __user *)(unsigned long)a.used_user_addr;
751 case VHOST_SET_VRING_KICK:
752 if (copy_from_user(&f, argp, sizeof f)) {
756 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
757 if (IS_ERR(eventfp)) {
758 r = PTR_ERR(eventfp);
761 if (eventfp != vq->kick) {
762 pollstop = (filep = vq->kick) != NULL;
763 pollstart = (vq->kick = eventfp) != NULL;
767 case VHOST_SET_VRING_CALL:
768 if (copy_from_user(&f, argp, sizeof f)) {
772 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
773 if (IS_ERR(eventfp)) {
774 r = PTR_ERR(eventfp);
777 if (eventfp != vq->call) {
781 vq->call_ctx = eventfp ?
782 eventfd_ctx_fileget(eventfp) : NULL;
786 case VHOST_SET_VRING_ERR:
787 if (copy_from_user(&f, argp, sizeof f)) {
791 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
792 if (IS_ERR(eventfp)) {
793 r = PTR_ERR(eventfp);
796 if (eventfp != vq->error) {
800 vq->error_ctx = eventfp ?
801 eventfd_ctx_fileget(eventfp) : NULL;
809 if (pollstop && vq->handle_kick)
810 vhost_poll_stop(&vq->poll);
813 eventfd_ctx_put(ctx);
817 if (pollstart && vq->handle_kick)
818 r = vhost_poll_start(&vq->poll, vq->kick);
820 mutex_unlock(&vq->mutex);
822 if (pollstop && vq->handle_kick)
823 vhost_poll_flush(&vq->poll);
826 EXPORT_SYMBOL_GPL(vhost_vring_ioctl);
828 /* Caller must have device mutex */
829 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
831 struct file *eventfp, *filep = NULL;
832 struct eventfd_ctx *ctx = NULL;
837 /* If you are not the owner, you can become one */
838 if (ioctl == VHOST_SET_OWNER) {
839 r = vhost_dev_set_owner(d);
843 /* You must be the owner to do anything else */
844 r = vhost_dev_check_owner(d);
849 case VHOST_SET_MEM_TABLE:
850 r = vhost_set_memory(d, argp);
852 case VHOST_SET_LOG_BASE:
853 if (copy_from_user(&p, argp, sizeof p)) {
857 if ((u64)(unsigned long)p != p) {
861 for (i = 0; i < d->nvqs; ++i) {
862 struct vhost_virtqueue *vq;
863 void __user *base = (void __user *)(unsigned long)p;
865 mutex_lock(&vq->mutex);
866 /* If ring is inactive, will check when it's enabled. */
867 if (vq->private_data && !vq_log_access_ok(vq, base))
871 mutex_unlock(&vq->mutex);
874 case VHOST_SET_LOG_FD:
875 r = get_user(fd, (int __user *)argp);
878 eventfp = fd == -1 ? NULL : eventfd_fget(fd);
879 if (IS_ERR(eventfp)) {
880 r = PTR_ERR(eventfp);
883 if (eventfp != d->log_file) {
886 d->log_ctx = eventfp ?
887 eventfd_ctx_fileget(eventfp) : NULL;
890 for (i = 0; i < d->nvqs; ++i) {
891 mutex_lock(&d->vqs[i]->mutex);
892 d->vqs[i]->log_ctx = d->log_ctx;
893 mutex_unlock(&d->vqs[i]->mutex);
896 eventfd_ctx_put(ctx);
907 EXPORT_SYMBOL_GPL(vhost_dev_ioctl);
909 static const struct vhost_memory_region *find_region(struct vhost_memory *mem,
910 __u64 addr, __u32 len)
912 struct vhost_memory_region *reg;
915 /* linear search is not brilliant, but we really have on the order of 6
916 * regions in practice */
917 for (i = 0; i < mem->nregions; ++i) {
918 reg = mem->regions + i;
919 if (reg->guest_phys_addr <= addr &&
920 reg->guest_phys_addr + reg->memory_size - 1 >= addr)
926 /* TODO: This is really inefficient. We need something like get_user()
927 * (instruction directly accesses the data, with an exception table entry
928 * returning -EFAULT). See Documentation/x86/exception-tables.txt.
930 static int set_bit_to_user(int nr, void __user *addr)
932 unsigned long log = (unsigned long)addr;
935 int bit = nr + (log % PAGE_SIZE) * 8;
938 r = get_user_pages_fast(log, 1, 1, &page);
942 base = kmap_atomic(page);
945 set_page_dirty_lock(page);
950 static int log_write(void __user *log_base,
951 u64 write_address, u64 write_length)
953 u64 write_page = write_address / VHOST_PAGE_SIZE;
958 write_length += write_address % VHOST_PAGE_SIZE;
960 u64 base = (u64)(unsigned long)log_base;
961 u64 log = base + write_page / 8;
962 int bit = write_page % 8;
963 if ((u64)(unsigned long)log != log)
965 r = set_bit_to_user(bit, (void __user *)(unsigned long)log);
968 if (write_length <= VHOST_PAGE_SIZE)
970 write_length -= VHOST_PAGE_SIZE;
976 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
977 unsigned int log_num, u64 len)
981 /* Make sure data written is seen before log. */
983 for (i = 0; i < log_num; ++i) {
984 u64 l = min(log[i].len, len);
985 r = log_write(vq->log_base, log[i].addr, l);
991 eventfd_signal(vq->log_ctx, 1);
995 /* Length written exceeds what we have stored. This is a bug. */
999 EXPORT_SYMBOL_GPL(vhost_log_write);
1001 static int vhost_update_used_flags(struct vhost_virtqueue *vq)
1004 if (__put_user(vq->used_flags, &vq->used->flags) < 0)
1006 if (unlikely(vq->log_used)) {
1007 /* Make sure the flag is seen before log. */
1009 /* Log used flag write. */
1010 used = &vq->used->flags;
1011 log_write(vq->log_base, vq->log_addr +
1012 (used - (void __user *)vq->used),
1013 sizeof vq->used->flags);
1015 eventfd_signal(vq->log_ctx, 1);
1020 static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event)
1022 if (__put_user(vq->avail_idx, vhost_avail_event(vq)))
1024 if (unlikely(vq->log_used)) {
1026 /* Make sure the event is seen before log. */
1028 /* Log avail event write */
1029 used = vhost_avail_event(vq);
1030 log_write(vq->log_base, vq->log_addr +
1031 (used - (void __user *)vq->used),
1032 sizeof *vhost_avail_event(vq));
1034 eventfd_signal(vq->log_ctx, 1);
1039 int vhost_init_used(struct vhost_virtqueue *vq)
1042 if (!vq->private_data)
1045 r = vhost_update_used_flags(vq);
1048 vq->signalled_used_valid = false;
1049 return get_user(vq->last_used_idx, &vq->used->idx);
1051 EXPORT_SYMBOL_GPL(vhost_init_used);
1053 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
1054 struct iovec iov[], int iov_size)
1056 const struct vhost_memory_region *reg;
1057 struct vhost_memory *mem;
1063 while ((u64)len > s) {
1065 if (unlikely(ret >= iov_size)) {
1069 reg = find_region(mem, addr, len);
1070 if (unlikely(!reg)) {
1075 size = reg->memory_size - addr + reg->guest_phys_addr;
1076 _iov->iov_len = min((u64)len - s, size);
1077 _iov->iov_base = (void __user *)(unsigned long)
1078 (reg->userspace_addr + addr - reg->guest_phys_addr);
1087 /* Each buffer in the virtqueues is actually a chain of descriptors. This
1088 * function returns the next descriptor in the chain,
1089 * or -1U if we're at the end. */
1090 static unsigned next_desc(struct vring_desc *desc)
1094 /* If this descriptor says it doesn't chain, we're done. */
1095 if (!(desc->flags & VRING_DESC_F_NEXT))
1098 /* Check they're not leading us off end of descriptors. */
1100 /* Make sure compiler knows to grab that: we don't want it changing! */
1101 /* We will use the result as an index in an array, so most
1102 * architectures only need a compiler barrier here. */
1103 read_barrier_depends();
1108 static int get_indirect(struct vhost_virtqueue *vq,
1109 struct iovec iov[], unsigned int iov_size,
1110 unsigned int *out_num, unsigned int *in_num,
1111 struct vhost_log *log, unsigned int *log_num,
1112 struct vring_desc *indirect)
1114 struct vring_desc desc;
1115 unsigned int i = 0, count, found = 0;
1119 if (unlikely(indirect->len % sizeof desc)) {
1120 vq_err(vq, "Invalid length in indirect descriptor: "
1121 "len 0x%llx not multiple of 0x%zx\n",
1122 (unsigned long long)indirect->len,
1127 ret = translate_desc(vq, indirect->addr, indirect->len, vq->indirect,
1129 if (unlikely(ret < 0)) {
1130 vq_err(vq, "Translation failure %d in indirect.\n", ret);
1134 /* We will use the result as an address to read from, so most
1135 * architectures only need a compiler barrier here. */
1136 read_barrier_depends();
1138 count = indirect->len / sizeof desc;
1139 /* Buffers are chained via a 16 bit next field, so
1140 * we can have at most 2^16 of these. */
1141 if (unlikely(count > USHRT_MAX + 1)) {
1142 vq_err(vq, "Indirect buffer length too big: %d\n",
1148 unsigned iov_count = *in_num + *out_num;
1149 if (unlikely(++found > count)) {
1150 vq_err(vq, "Loop detected: last one at %u "
1151 "indirect size %u\n",
1155 if (unlikely(memcpy_fromiovec((unsigned char *)&desc,
1156 vq->indirect, sizeof desc))) {
1157 vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n",
1158 i, (size_t)indirect->addr + i * sizeof desc);
1161 if (unlikely(desc.flags & VRING_DESC_F_INDIRECT)) {
1162 vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n",
1163 i, (size_t)indirect->addr + i * sizeof desc);
1167 ret = translate_desc(vq, desc.addr, desc.len, iov + iov_count,
1168 iov_size - iov_count);
1169 if (unlikely(ret < 0)) {
1170 vq_err(vq, "Translation failure %d indirect idx %d\n",
1174 /* If this is an input descriptor, increment that count. */
1175 if (desc.flags & VRING_DESC_F_WRITE) {
1177 if (unlikely(log)) {
1178 log[*log_num].addr = desc.addr;
1179 log[*log_num].len = desc.len;
1183 /* If it's an output descriptor, they're all supposed
1184 * to come before any input descriptors. */
1185 if (unlikely(*in_num)) {
1186 vq_err(vq, "Indirect descriptor "
1187 "has out after in: idx %d\n", i);
1192 } while ((i = next_desc(&desc)) != -1);
1196 /* This looks in the virtqueue and for the first available buffer, and converts
1197 * it to an iovec for convenient access. Since descriptors consist of some
1198 * number of output then some number of input descriptors, it's actually two
1199 * iovecs, but we pack them into one and note how many of each there were.
1201 * This function returns the descriptor number found, or vq->num (which is
1202 * never a valid descriptor number) if none was found. A negative code is
1203 * returned on error. */
1204 int vhost_get_vq_desc(struct vhost_virtqueue *vq,
1205 struct iovec iov[], unsigned int iov_size,
1206 unsigned int *out_num, unsigned int *in_num,
1207 struct vhost_log *log, unsigned int *log_num)
1209 struct vring_desc desc;
1210 unsigned int i, head, found = 0;
1214 /* Check it isn't doing very strange things with descriptor numbers. */
1215 last_avail_idx = vq->last_avail_idx;
1216 if (unlikely(__get_user(vq->avail_idx, &vq->avail->idx))) {
1217 vq_err(vq, "Failed to access avail idx at %p\n",
1222 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
1223 vq_err(vq, "Guest moved used index from %u to %u",
1224 last_avail_idx, vq->avail_idx);
1228 /* If there's nothing new since last we looked, return invalid. */
1229 if (vq->avail_idx == last_avail_idx)
1232 /* Only get avail ring entries after they have been exposed by guest. */
1235 /* Grab the next descriptor number they're advertising, and increment
1236 * the index we've seen. */
1237 if (unlikely(__get_user(head,
1238 &vq->avail->ring[last_avail_idx % vq->num]))) {
1239 vq_err(vq, "Failed to read head: idx %d address %p\n",
1241 &vq->avail->ring[last_avail_idx % vq->num]);
1245 /* If their number is silly, that's an error. */
1246 if (unlikely(head >= vq->num)) {
1247 vq_err(vq, "Guest says index %u > %u is available",
1252 /* When we start there are none of either input nor output. */
1253 *out_num = *in_num = 0;
1259 unsigned iov_count = *in_num + *out_num;
1260 if (unlikely(i >= vq->num)) {
1261 vq_err(vq, "Desc index is %u > %u, head = %u",
1265 if (unlikely(++found > vq->num)) {
1266 vq_err(vq, "Loop detected: last one at %u "
1267 "vq size %u head %u\n",
1271 ret = __copy_from_user(&desc, vq->desc + i, sizeof desc);
1272 if (unlikely(ret)) {
1273 vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
1277 if (desc.flags & VRING_DESC_F_INDIRECT) {
1278 ret = get_indirect(vq, iov, iov_size,
1280 log, log_num, &desc);
1281 if (unlikely(ret < 0)) {
1282 vq_err(vq, "Failure detected "
1283 "in indirect descriptor at idx %d\n", i);
1289 ret = translate_desc(vq, desc.addr, desc.len, iov + iov_count,
1290 iov_size - iov_count);
1291 if (unlikely(ret < 0)) {
1292 vq_err(vq, "Translation failure %d descriptor idx %d\n",
1296 if (desc.flags & VRING_DESC_F_WRITE) {
1297 /* If this is an input descriptor,
1298 * increment that count. */
1300 if (unlikely(log)) {
1301 log[*log_num].addr = desc.addr;
1302 log[*log_num].len = desc.len;
1306 /* If it's an output descriptor, they're all supposed
1307 * to come before any input descriptors. */
1308 if (unlikely(*in_num)) {
1309 vq_err(vq, "Descriptor has out after in: "
1315 } while ((i = next_desc(&desc)) != -1);
1317 /* On success, increment avail index. */
1318 vq->last_avail_idx++;
1320 /* Assume notifications from guest are disabled at this point,
1321 * if they aren't we would need to update avail_event index. */
1322 BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
1325 EXPORT_SYMBOL_GPL(vhost_get_vq_desc);
1327 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
1328 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
1330 vq->last_avail_idx -= n;
1332 EXPORT_SYMBOL_GPL(vhost_discard_vq_desc);
1334 /* After we've used one of their buffers, we tell them about it. We'll then
1335 * want to notify the guest, using eventfd. */
1336 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
1338 struct vring_used_elem heads = { head, len };
1340 return vhost_add_used_n(vq, &heads, 1);
1342 EXPORT_SYMBOL_GPL(vhost_add_used);
1344 static int __vhost_add_used_n(struct vhost_virtqueue *vq,
1345 struct vring_used_elem *heads,
1348 struct vring_used_elem __user *used;
1352 start = vq->last_used_idx % vq->num;
1353 used = vq->used->ring + start;
1355 if (__put_user(heads[0].id, &used->id)) {
1356 vq_err(vq, "Failed to write used id");
1359 if (__put_user(heads[0].len, &used->len)) {
1360 vq_err(vq, "Failed to write used len");
1363 } else if (__copy_to_user(used, heads, count * sizeof *used)) {
1364 vq_err(vq, "Failed to write used");
1367 if (unlikely(vq->log_used)) {
1368 /* Make sure data is seen before log. */
1370 /* Log used ring entry write. */
1371 log_write(vq->log_base,
1373 ((void __user *)used - (void __user *)vq->used),
1374 count * sizeof *used);
1376 old = vq->last_used_idx;
1377 new = (vq->last_used_idx += count);
1378 /* If the driver never bothers to signal in a very long while,
1379 * used index might wrap around. If that happens, invalidate
1380 * signalled_used index we stored. TODO: make sure driver
1381 * signals at least once in 2^16 and remove this. */
1382 if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old)))
1383 vq->signalled_used_valid = false;
1387 /* After we've used one of their buffers, we tell them about it. We'll then
1388 * want to notify the guest, using eventfd. */
1389 int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
1394 start = vq->last_used_idx % vq->num;
1395 n = vq->num - start;
1397 r = __vhost_add_used_n(vq, heads, n);
1403 r = __vhost_add_used_n(vq, heads, count);
1405 /* Make sure buffer is written before we update index. */
1407 if (put_user(vq->last_used_idx, &vq->used->idx)) {
1408 vq_err(vq, "Failed to increment used idx");
1411 if (unlikely(vq->log_used)) {
1412 /* Log used index update. */
1413 log_write(vq->log_base,
1414 vq->log_addr + offsetof(struct vring_used, idx),
1415 sizeof vq->used->idx);
1417 eventfd_signal(vq->log_ctx, 1);
1421 EXPORT_SYMBOL_GPL(vhost_add_used_n);
1423 static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1425 __u16 old, new, event;
1427 /* Flush out used index updates. This is paired
1428 * with the barrier that the Guest executes when enabling
1432 if (vhost_has_feature(vq, VIRTIO_F_NOTIFY_ON_EMPTY) &&
1433 unlikely(vq->avail_idx == vq->last_avail_idx))
1436 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
1438 if (__get_user(flags, &vq->avail->flags)) {
1439 vq_err(vq, "Failed to get flags");
1442 return !(flags & VRING_AVAIL_F_NO_INTERRUPT);
1444 old = vq->signalled_used;
1445 v = vq->signalled_used_valid;
1446 new = vq->signalled_used = vq->last_used_idx;
1447 vq->signalled_used_valid = true;
1452 if (get_user(event, vhost_used_event(vq))) {
1453 vq_err(vq, "Failed to get used event idx");
1456 return vring_need_event(event, new, old);
1459 /* This actually signals the guest, using eventfd. */
1460 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1462 /* Signal the Guest tell them we used something up. */
1463 if (vq->call_ctx && vhost_notify(dev, vq))
1464 eventfd_signal(vq->call_ctx, 1);
1466 EXPORT_SYMBOL_GPL(vhost_signal);
1468 /* And here's the combo meal deal. Supersize me! */
1469 void vhost_add_used_and_signal(struct vhost_dev *dev,
1470 struct vhost_virtqueue *vq,
1471 unsigned int head, int len)
1473 vhost_add_used(vq, head, len);
1474 vhost_signal(dev, vq);
1476 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal);
1478 /* multi-buffer version of vhost_add_used_and_signal */
1479 void vhost_add_used_and_signal_n(struct vhost_dev *dev,
1480 struct vhost_virtqueue *vq,
1481 struct vring_used_elem *heads, unsigned count)
1483 vhost_add_used_n(vq, heads, count);
1484 vhost_signal(dev, vq);
1486 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n);
1488 /* OK, now we need to know about added descriptors. */
1489 bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1494 if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
1496 vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
1497 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
1498 r = vhost_update_used_flags(vq);
1500 vq_err(vq, "Failed to enable notification at %p: %d\n",
1501 &vq->used->flags, r);
1505 r = vhost_update_avail_event(vq, vq->avail_idx);
1507 vq_err(vq, "Failed to update avail event index at %p: %d\n",
1508 vhost_avail_event(vq), r);
1512 /* They could have slipped one in as we were doing that: make
1513 * sure it's written, then check again. */
1515 r = __get_user(avail_idx, &vq->avail->idx);
1517 vq_err(vq, "Failed to check avail idx at %p: %d\n",
1518 &vq->avail->idx, r);
1522 return avail_idx != vq->avail_idx;
1524 EXPORT_SYMBOL_GPL(vhost_enable_notify);
1526 /* We don't need to be notified again. */
1527 void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
1531 if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
1533 vq->used_flags |= VRING_USED_F_NO_NOTIFY;
1534 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
1535 r = vhost_update_used_flags(vq);
1537 vq_err(vq, "Failed to enable notification at %p: %d\n",
1538 &vq->used->flags, r);
1541 EXPORT_SYMBOL_GPL(vhost_disable_notify);
1543 static int __init vhost_init(void)
1548 static void __exit vhost_exit(void)
1552 module_init(vhost_init);
1553 module_exit(vhost_exit);
1555 MODULE_VERSION("0.0.1");
1556 MODULE_LICENSE("GPL v2");
1557 MODULE_AUTHOR("Michael S. Tsirkin");
1558 MODULE_DESCRIPTION("Host kernel accelerator for virtio");