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/socket.h> /* memcpy_fromiovec */
18 #include <linux/mmu_context.h>
19 #include <linux/miscdevice.h>
20 #include <linux/mutex.h>
21 #include <linux/rcupdate.h>
22 #include <linux/poll.h>
23 #include <linux/file.h>
24 #include <linux/highmem.h>
25 #include <linux/slab.h>
26 #include <linux/kthread.h>
27 #include <linux/cgroup.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;
70 /* Init poll structure */
71 void vhost_poll_init(struct vhost_poll
*poll
, vhost_work_fn_t fn
,
72 unsigned long mask
, struct vhost_dev
*dev
)
74 init_waitqueue_func_entry(&poll
->wait
, vhost_poll_wakeup
);
75 init_poll_funcptr(&poll
->table
, vhost_poll_func
);
80 vhost_work_init(&poll
->work
, fn
);
83 /* Start polling a file. We add ourselves to file's wait queue. The caller must
84 * keep a reference to a file until after vhost_poll_stop is called. */
85 int vhost_poll_start(struct vhost_poll
*poll
, struct file
*file
)
93 mask
= file
->f_op
->poll(file
, &poll
->table
);
95 vhost_poll_wakeup(&poll
->wait
, 0, 0, (void *)mask
);
98 remove_wait_queue(poll
->wqh
, &poll
->wait
);
105 /* Stop polling a file. After this function returns, it becomes safe to drop the
106 * file reference. You must also flush afterwards. */
107 void vhost_poll_stop(struct vhost_poll
*poll
)
110 remove_wait_queue(poll
->wqh
, &poll
->wait
);
115 static bool vhost_work_seq_done(struct vhost_dev
*dev
, struct vhost_work
*work
,
120 spin_lock_irq(&dev
->work_lock
);
121 left
= seq
- work
->done_seq
;
122 spin_unlock_irq(&dev
->work_lock
);
126 static void vhost_work_flush(struct vhost_dev
*dev
, struct vhost_work
*work
)
131 spin_lock_irq(&dev
->work_lock
);
132 seq
= work
->queue_seq
;
134 spin_unlock_irq(&dev
->work_lock
);
135 wait_event(work
->done
, vhost_work_seq_done(dev
, work
, seq
));
136 spin_lock_irq(&dev
->work_lock
);
137 flushing
= --work
->flushing
;
138 spin_unlock_irq(&dev
->work_lock
);
139 BUG_ON(flushing
< 0);
142 /* Flush any work that has been scheduled. When calling this, don't hold any
143 * locks that are also used by the callback. */
144 void vhost_poll_flush(struct vhost_poll
*poll
)
146 vhost_work_flush(poll
->dev
, &poll
->work
);
149 void vhost_work_queue(struct vhost_dev
*dev
, struct vhost_work
*work
)
153 spin_lock_irqsave(&dev
->work_lock
, flags
);
154 if (list_empty(&work
->node
)) {
155 list_add_tail(&work
->node
, &dev
->work_list
);
157 wake_up_process(dev
->worker
);
159 spin_unlock_irqrestore(&dev
->work_lock
, flags
);
162 void vhost_poll_queue(struct vhost_poll
*poll
)
164 vhost_work_queue(poll
->dev
, &poll
->work
);
167 static void vhost_vq_reset(struct vhost_dev
*dev
,
168 struct vhost_virtqueue
*vq
)
174 vq
->last_avail_idx
= 0;
176 vq
->last_used_idx
= 0;
177 vq
->signalled_used
= 0;
178 vq
->signalled_used_valid
= false;
180 vq
->log_used
= false;
181 vq
->log_addr
= -1ull;
182 vq
->private_data
= NULL
;
184 vq
->error_ctx
= NULL
;
192 static int vhost_worker(void *data
)
194 struct vhost_dev
*dev
= data
;
195 struct vhost_work
*work
= NULL
;
196 unsigned uninitialized_var(seq
);
197 mm_segment_t oldfs
= get_fs();
203 /* mb paired w/ kthread_stop */
204 set_current_state(TASK_INTERRUPTIBLE
);
206 spin_lock_irq(&dev
->work_lock
);
208 work
->done_seq
= seq
;
210 wake_up_all(&work
->done
);
213 if (kthread_should_stop()) {
214 spin_unlock_irq(&dev
->work_lock
);
215 __set_current_state(TASK_RUNNING
);
218 if (!list_empty(&dev
->work_list
)) {
219 work
= list_first_entry(&dev
->work_list
,
220 struct vhost_work
, node
);
221 list_del_init(&work
->node
);
222 seq
= work
->queue_seq
;
225 spin_unlock_irq(&dev
->work_lock
);
228 __set_current_state(TASK_RUNNING
);
241 static void vhost_vq_free_iovecs(struct vhost_virtqueue
*vq
)
251 /* Helper to allocate iovec buffers for all vqs. */
252 static long vhost_dev_alloc_iovecs(struct vhost_dev
*dev
)
256 for (i
= 0; i
< dev
->nvqs
; ++i
) {
257 dev
->vqs
[i
]->indirect
= kmalloc(sizeof *dev
->vqs
[i
]->indirect
*
258 UIO_MAXIOV
, GFP_KERNEL
);
259 dev
->vqs
[i
]->log
= kmalloc(sizeof *dev
->vqs
[i
]->log
* UIO_MAXIOV
,
261 dev
->vqs
[i
]->heads
= kmalloc(sizeof *dev
->vqs
[i
]->heads
*
262 UIO_MAXIOV
, GFP_KERNEL
);
263 if (!dev
->vqs
[i
]->indirect
|| !dev
->vqs
[i
]->log
||
271 vhost_vq_free_iovecs(dev
->vqs
[i
]);
275 static void vhost_dev_free_iovecs(struct vhost_dev
*dev
)
279 for (i
= 0; i
< dev
->nvqs
; ++i
)
280 vhost_vq_free_iovecs(dev
->vqs
[i
]);
283 long vhost_dev_init(struct vhost_dev
*dev
,
284 struct vhost_virtqueue
**vqs
, int nvqs
)
290 mutex_init(&dev
->mutex
);
292 dev
->log_file
= NULL
;
295 spin_lock_init(&dev
->work_lock
);
296 INIT_LIST_HEAD(&dev
->work_list
);
299 for (i
= 0; i
< dev
->nvqs
; ++i
) {
300 dev
->vqs
[i
]->log
= NULL
;
301 dev
->vqs
[i
]->indirect
= NULL
;
302 dev
->vqs
[i
]->heads
= NULL
;
303 dev
->vqs
[i
]->dev
= dev
;
304 mutex_init(&dev
->vqs
[i
]->mutex
);
305 vhost_vq_reset(dev
, dev
->vqs
[i
]);
306 if (dev
->vqs
[i
]->handle_kick
)
307 vhost_poll_init(&dev
->vqs
[i
]->poll
,
308 dev
->vqs
[i
]->handle_kick
, POLLIN
, dev
);
314 /* Caller should have device mutex */
315 long vhost_dev_check_owner(struct vhost_dev
*dev
)
317 /* Are you the owner? If not, I don't think you mean to do that */
318 return dev
->mm
== current
->mm
? 0 : -EPERM
;
321 struct vhost_attach_cgroups_struct
{
322 struct vhost_work work
;
323 struct task_struct
*owner
;
327 static void vhost_attach_cgroups_work(struct vhost_work
*work
)
329 struct vhost_attach_cgroups_struct
*s
;
331 s
= container_of(work
, struct vhost_attach_cgroups_struct
, work
);
332 s
->ret
= cgroup_attach_task_all(s
->owner
, current
);
335 static int vhost_attach_cgroups(struct vhost_dev
*dev
)
337 struct vhost_attach_cgroups_struct attach
;
339 attach
.owner
= current
;
340 vhost_work_init(&attach
.work
, vhost_attach_cgroups_work
);
341 vhost_work_queue(dev
, &attach
.work
);
342 vhost_work_flush(dev
, &attach
.work
);
346 /* Caller should have device mutex */
347 bool vhost_dev_has_owner(struct vhost_dev
*dev
)
352 /* Caller should have device mutex */
353 long vhost_dev_set_owner(struct vhost_dev
*dev
)
355 struct task_struct
*worker
;
358 /* Is there an owner already? */
359 if (vhost_dev_has_owner(dev
)) {
364 /* No owner, become one */
365 dev
->mm
= get_task_mm(current
);
366 worker
= kthread_create(vhost_worker
, dev
, "vhost-%d", current
->pid
);
367 if (IS_ERR(worker
)) {
368 err
= PTR_ERR(worker
);
372 dev
->worker
= worker
;
373 wake_up_process(worker
); /* avoid contributing to loadavg */
375 err
= vhost_attach_cgroups(dev
);
379 err
= vhost_dev_alloc_iovecs(dev
);
385 kthread_stop(worker
);
395 struct vhost_memory
*vhost_dev_reset_owner_prepare(void)
397 return kmalloc(offsetof(struct vhost_memory
, regions
), GFP_KERNEL
);
400 /* Caller should have device mutex */
401 void vhost_dev_reset_owner(struct vhost_dev
*dev
, struct vhost_memory
*memory
)
403 vhost_dev_cleanup(dev
, true);
405 /* Restore memory to default empty mapping. */
406 memory
->nregions
= 0;
407 RCU_INIT_POINTER(dev
->memory
, memory
);
410 void vhost_dev_stop(struct vhost_dev
*dev
)
414 for (i
= 0; i
< dev
->nvqs
; ++i
) {
415 if (dev
->vqs
[i
]->kick
&& dev
->vqs
[i
]->handle_kick
) {
416 vhost_poll_stop(&dev
->vqs
[i
]->poll
);
417 vhost_poll_flush(&dev
->vqs
[i
]->poll
);
422 /* Caller should have device mutex if and only if locked is set */
423 void vhost_dev_cleanup(struct vhost_dev
*dev
, bool locked
)
427 for (i
= 0; i
< dev
->nvqs
; ++i
) {
428 if (dev
->vqs
[i
]->error_ctx
)
429 eventfd_ctx_put(dev
->vqs
[i
]->error_ctx
);
430 if (dev
->vqs
[i
]->error
)
431 fput(dev
->vqs
[i
]->error
);
432 if (dev
->vqs
[i
]->kick
)
433 fput(dev
->vqs
[i
]->kick
);
434 if (dev
->vqs
[i
]->call_ctx
)
435 eventfd_ctx_put(dev
->vqs
[i
]->call_ctx
);
436 if (dev
->vqs
[i
]->call
)
437 fput(dev
->vqs
[i
]->call
);
438 vhost_vq_reset(dev
, dev
->vqs
[i
]);
440 vhost_dev_free_iovecs(dev
);
442 eventfd_ctx_put(dev
->log_ctx
);
446 dev
->log_file
= NULL
;
447 /* No one will access memory at this point */
448 kfree(rcu_dereference_protected(dev
->memory
,
450 lockdep_is_held(&dev
->mutex
)));
451 RCU_INIT_POINTER(dev
->memory
, NULL
);
452 WARN_ON(!list_empty(&dev
->work_list
));
454 kthread_stop(dev
->worker
);
462 static int log_access_ok(void __user
*log_base
, u64 addr
, unsigned long sz
)
464 u64 a
= addr
/ VHOST_PAGE_SIZE
/ 8;
466 /* Make sure 64 bit math will not overflow. */
467 if (a
> ULONG_MAX
- (unsigned long)log_base
||
468 a
+ (unsigned long)log_base
> ULONG_MAX
)
471 return access_ok(VERIFY_WRITE
, log_base
+ a
,
472 (sz
+ VHOST_PAGE_SIZE
* 8 - 1) / VHOST_PAGE_SIZE
/ 8);
475 /* Caller should have vq mutex and device mutex. */
476 static int vq_memory_access_ok(void __user
*log_base
, struct vhost_memory
*mem
,
484 for (i
= 0; i
< mem
->nregions
; ++i
) {
485 struct vhost_memory_region
*m
= mem
->regions
+ i
;
486 unsigned long a
= m
->userspace_addr
;
487 if (m
->memory_size
> ULONG_MAX
)
489 else if (!access_ok(VERIFY_WRITE
, (void __user
*)a
,
492 else if (log_all
&& !log_access_ok(log_base
,
500 /* Can we switch to this memory table? */
501 /* Caller should have device mutex but not vq mutex */
502 static int memory_access_ok(struct vhost_dev
*d
, struct vhost_memory
*mem
,
507 for (i
= 0; i
< d
->nvqs
; ++i
) {
509 mutex_lock(&d
->vqs
[i
]->mutex
);
510 /* If ring is inactive, will check when it's enabled. */
511 if (d
->vqs
[i
]->private_data
)
512 ok
= vq_memory_access_ok(d
->vqs
[i
]->log_base
, mem
,
516 mutex_unlock(&d
->vqs
[i
]->mutex
);
523 static int vq_access_ok(struct vhost_dev
*d
, unsigned int num
,
524 struct vring_desc __user
*desc
,
525 struct vring_avail __user
*avail
,
526 struct vring_used __user
*used
)
528 size_t s
= vhost_has_feature(d
, VIRTIO_RING_F_EVENT_IDX
) ? 2 : 0;
529 return access_ok(VERIFY_READ
, desc
, num
* sizeof *desc
) &&
530 access_ok(VERIFY_READ
, avail
,
531 sizeof *avail
+ num
* sizeof *avail
->ring
+ s
) &&
532 access_ok(VERIFY_WRITE
, used
,
533 sizeof *used
+ num
* sizeof *used
->ring
+ s
);
536 /* Can we log writes? */
537 /* Caller should have device mutex but not vq mutex */
538 int vhost_log_access_ok(struct vhost_dev
*dev
)
540 struct vhost_memory
*mp
;
542 mp
= rcu_dereference_protected(dev
->memory
,
543 lockdep_is_held(&dev
->mutex
));
544 return memory_access_ok(dev
, mp
, 1);
547 /* Verify access for write logging. */
548 /* Caller should have vq mutex and device mutex */
549 static int vq_log_access_ok(struct vhost_dev
*d
, struct vhost_virtqueue
*vq
,
550 void __user
*log_base
)
552 struct vhost_memory
*mp
;
553 size_t s
= vhost_has_feature(d
, VIRTIO_RING_F_EVENT_IDX
) ? 2 : 0;
555 mp
= rcu_dereference_protected(vq
->dev
->memory
,
556 lockdep_is_held(&vq
->mutex
));
557 return vq_memory_access_ok(log_base
, mp
,
558 vhost_has_feature(vq
->dev
, VHOST_F_LOG_ALL
)) &&
559 (!vq
->log_used
|| log_access_ok(log_base
, vq
->log_addr
,
561 vq
->num
* sizeof *vq
->used
->ring
+ s
));
564 /* Can we start vq? */
565 /* Caller should have vq mutex and device mutex */
566 int vhost_vq_access_ok(struct vhost_virtqueue
*vq
)
568 return vq_access_ok(vq
->dev
, vq
->num
, vq
->desc
, vq
->avail
, vq
->used
) &&
569 vq_log_access_ok(vq
->dev
, vq
, vq
->log_base
);
572 static long vhost_set_memory(struct vhost_dev
*d
, struct vhost_memory __user
*m
)
574 struct vhost_memory mem
, *newmem
, *oldmem
;
575 unsigned long size
= offsetof(struct vhost_memory
, regions
);
577 if (copy_from_user(&mem
, m
, size
))
581 if (mem
.nregions
> VHOST_MEMORY_MAX_NREGIONS
)
583 newmem
= kmalloc(size
+ mem
.nregions
* sizeof *m
->regions
, GFP_KERNEL
);
587 memcpy(newmem
, &mem
, size
);
588 if (copy_from_user(newmem
->regions
, m
->regions
,
589 mem
.nregions
* sizeof *m
->regions
)) {
594 if (!memory_access_ok(d
, newmem
,
595 vhost_has_feature(d
, VHOST_F_LOG_ALL
))) {
599 oldmem
= rcu_dereference_protected(d
->memory
,
600 lockdep_is_held(&d
->mutex
));
601 rcu_assign_pointer(d
->memory
, newmem
);
607 long vhost_vring_ioctl(struct vhost_dev
*d
, int ioctl
, void __user
*argp
)
609 struct file
*eventfp
, *filep
= NULL
;
610 bool pollstart
= false, pollstop
= false;
611 struct eventfd_ctx
*ctx
= NULL
;
612 u32 __user
*idxp
= argp
;
613 struct vhost_virtqueue
*vq
;
614 struct vhost_vring_state s
;
615 struct vhost_vring_file f
;
616 struct vhost_vring_addr a
;
620 r
= get_user(idx
, idxp
);
628 mutex_lock(&vq
->mutex
);
631 case VHOST_SET_VRING_NUM
:
632 /* Resizing ring with an active backend?
633 * You don't want to do that. */
634 if (vq
->private_data
) {
638 if (copy_from_user(&s
, argp
, sizeof s
)) {
642 if (!s
.num
|| s
.num
> 0xffff || (s
.num
& (s
.num
- 1))) {
648 case VHOST_SET_VRING_BASE
:
649 /* Moving base with an active backend?
650 * You don't want to do that. */
651 if (vq
->private_data
) {
655 if (copy_from_user(&s
, argp
, sizeof s
)) {
659 if (s
.num
> 0xffff) {
663 vq
->last_avail_idx
= s
.num
;
664 /* Forget the cached index value. */
665 vq
->avail_idx
= vq
->last_avail_idx
;
667 case VHOST_GET_VRING_BASE
:
669 s
.num
= vq
->last_avail_idx
;
670 if (copy_to_user(argp
, &s
, sizeof s
))
673 case VHOST_SET_VRING_ADDR
:
674 if (copy_from_user(&a
, argp
, sizeof a
)) {
678 if (a
.flags
& ~(0x1 << VHOST_VRING_F_LOG
)) {
682 /* For 32bit, verify that the top 32bits of the user
683 data are set to zero. */
684 if ((u64
)(unsigned long)a
.desc_user_addr
!= a
.desc_user_addr
||
685 (u64
)(unsigned long)a
.used_user_addr
!= a
.used_user_addr
||
686 (u64
)(unsigned long)a
.avail_user_addr
!= a
.avail_user_addr
) {
690 if ((a
.avail_user_addr
& (sizeof *vq
->avail
->ring
- 1)) ||
691 (a
.used_user_addr
& (sizeof *vq
->used
->ring
- 1)) ||
692 (a
.log_guest_addr
& (sizeof *vq
->used
->ring
- 1))) {
697 /* We only verify access here if backend is configured.
698 * If it is not, we don't as size might not have been setup.
699 * We will verify when backend is configured. */
700 if (vq
->private_data
) {
701 if (!vq_access_ok(d
, vq
->num
,
702 (void __user
*)(unsigned long)a
.desc_user_addr
,
703 (void __user
*)(unsigned long)a
.avail_user_addr
,
704 (void __user
*)(unsigned long)a
.used_user_addr
)) {
709 /* Also validate log access for used ring if enabled. */
710 if ((a
.flags
& (0x1 << VHOST_VRING_F_LOG
)) &&
711 !log_access_ok(vq
->log_base
, a
.log_guest_addr
,
713 vq
->num
* sizeof *vq
->used
->ring
)) {
719 vq
->log_used
= !!(a
.flags
& (0x1 << VHOST_VRING_F_LOG
));
720 vq
->desc
= (void __user
*)(unsigned long)a
.desc_user_addr
;
721 vq
->avail
= (void __user
*)(unsigned long)a
.avail_user_addr
;
722 vq
->log_addr
= a
.log_guest_addr
;
723 vq
->used
= (void __user
*)(unsigned long)a
.used_user_addr
;
725 case VHOST_SET_VRING_KICK
:
726 if (copy_from_user(&f
, argp
, sizeof f
)) {
730 eventfp
= f
.fd
== -1 ? NULL
: eventfd_fget(f
.fd
);
731 if (IS_ERR(eventfp
)) {
732 r
= PTR_ERR(eventfp
);
735 if (eventfp
!= vq
->kick
) {
736 pollstop
= (filep
= vq
->kick
) != NULL
;
737 pollstart
= (vq
->kick
= eventfp
) != NULL
;
741 case VHOST_SET_VRING_CALL
:
742 if (copy_from_user(&f
, argp
, sizeof f
)) {
746 eventfp
= f
.fd
== -1 ? NULL
: eventfd_fget(f
.fd
);
747 if (IS_ERR(eventfp
)) {
748 r
= PTR_ERR(eventfp
);
751 if (eventfp
!= vq
->call
) {
755 vq
->call_ctx
= eventfp
?
756 eventfd_ctx_fileget(eventfp
) : NULL
;
760 case VHOST_SET_VRING_ERR
:
761 if (copy_from_user(&f
, argp
, sizeof f
)) {
765 eventfp
= f
.fd
== -1 ? NULL
: eventfd_fget(f
.fd
);
766 if (IS_ERR(eventfp
)) {
767 r
= PTR_ERR(eventfp
);
770 if (eventfp
!= vq
->error
) {
774 vq
->error_ctx
= eventfp
?
775 eventfd_ctx_fileget(eventfp
) : NULL
;
783 if (pollstop
&& vq
->handle_kick
)
784 vhost_poll_stop(&vq
->poll
);
787 eventfd_ctx_put(ctx
);
791 if (pollstart
&& vq
->handle_kick
)
792 r
= vhost_poll_start(&vq
->poll
, vq
->kick
);
794 mutex_unlock(&vq
->mutex
);
796 if (pollstop
&& vq
->handle_kick
)
797 vhost_poll_flush(&vq
->poll
);
801 /* Caller must have device mutex */
802 long vhost_dev_ioctl(struct vhost_dev
*d
, unsigned int ioctl
, void __user
*argp
)
804 struct file
*eventfp
, *filep
= NULL
;
805 struct eventfd_ctx
*ctx
= NULL
;
810 /* If you are not the owner, you can become one */
811 if (ioctl
== VHOST_SET_OWNER
) {
812 r
= vhost_dev_set_owner(d
);
816 /* You must be the owner to do anything else */
817 r
= vhost_dev_check_owner(d
);
822 case VHOST_SET_MEM_TABLE
:
823 r
= vhost_set_memory(d
, argp
);
825 case VHOST_SET_LOG_BASE
:
826 if (copy_from_user(&p
, argp
, sizeof p
)) {
830 if ((u64
)(unsigned long)p
!= p
) {
834 for (i
= 0; i
< d
->nvqs
; ++i
) {
835 struct vhost_virtqueue
*vq
;
836 void __user
*base
= (void __user
*)(unsigned long)p
;
838 mutex_lock(&vq
->mutex
);
839 /* If ring is inactive, will check when it's enabled. */
840 if (vq
->private_data
&& !vq_log_access_ok(d
, vq
, base
))
844 mutex_unlock(&vq
->mutex
);
847 case VHOST_SET_LOG_FD
:
848 r
= get_user(fd
, (int __user
*)argp
);
851 eventfp
= fd
== -1 ? NULL
: eventfd_fget(fd
);
852 if (IS_ERR(eventfp
)) {
853 r
= PTR_ERR(eventfp
);
856 if (eventfp
!= d
->log_file
) {
859 d
->log_ctx
= eventfp
?
860 eventfd_ctx_fileget(eventfp
) : NULL
;
863 for (i
= 0; i
< d
->nvqs
; ++i
) {
864 mutex_lock(&d
->vqs
[i
]->mutex
);
865 d
->vqs
[i
]->log_ctx
= d
->log_ctx
;
866 mutex_unlock(&d
->vqs
[i
]->mutex
);
869 eventfd_ctx_put(ctx
);
881 static const struct vhost_memory_region
*find_region(struct vhost_memory
*mem
,
882 __u64 addr
, __u32 len
)
884 struct vhost_memory_region
*reg
;
887 /* linear search is not brilliant, but we really have on the order of 6
888 * regions in practice */
889 for (i
= 0; i
< mem
->nregions
; ++i
) {
890 reg
= mem
->regions
+ i
;
891 if (reg
->guest_phys_addr
<= addr
&&
892 reg
->guest_phys_addr
+ reg
->memory_size
- 1 >= addr
)
898 /* TODO: This is really inefficient. We need something like get_user()
899 * (instruction directly accesses the data, with an exception table entry
900 * returning -EFAULT). See Documentation/x86/exception-tables.txt.
902 static int set_bit_to_user(int nr
, void __user
*addr
)
904 unsigned long log
= (unsigned long)addr
;
907 int bit
= nr
+ (log
% PAGE_SIZE
) * 8;
910 r
= get_user_pages_fast(log
, 1, 1, &page
);
914 base
= kmap_atomic(page
);
917 set_page_dirty_lock(page
);
922 static int log_write(void __user
*log_base
,
923 u64 write_address
, u64 write_length
)
925 u64 write_page
= write_address
/ VHOST_PAGE_SIZE
;
930 write_length
+= write_address
% VHOST_PAGE_SIZE
;
932 u64 base
= (u64
)(unsigned long)log_base
;
933 u64 log
= base
+ write_page
/ 8;
934 int bit
= write_page
% 8;
935 if ((u64
)(unsigned long)log
!= log
)
937 r
= set_bit_to_user(bit
, (void __user
*)(unsigned long)log
);
940 if (write_length
<= VHOST_PAGE_SIZE
)
942 write_length
-= VHOST_PAGE_SIZE
;
948 int vhost_log_write(struct vhost_virtqueue
*vq
, struct vhost_log
*log
,
949 unsigned int log_num
, u64 len
)
953 /* Make sure data written is seen before log. */
955 for (i
= 0; i
< log_num
; ++i
) {
956 u64 l
= min(log
[i
].len
, len
);
957 r
= log_write(vq
->log_base
, log
[i
].addr
, l
);
963 eventfd_signal(vq
->log_ctx
, 1);
967 /* Length written exceeds what we have stored. This is a bug. */
972 static int vhost_update_used_flags(struct vhost_virtqueue
*vq
)
975 if (__put_user(vq
->used_flags
, &vq
->used
->flags
) < 0)
977 if (unlikely(vq
->log_used
)) {
978 /* Make sure the flag is seen before log. */
980 /* Log used flag write. */
981 used
= &vq
->used
->flags
;
982 log_write(vq
->log_base
, vq
->log_addr
+
983 (used
- (void __user
*)vq
->used
),
984 sizeof vq
->used
->flags
);
986 eventfd_signal(vq
->log_ctx
, 1);
991 static int vhost_update_avail_event(struct vhost_virtqueue
*vq
, u16 avail_event
)
993 if (__put_user(vq
->avail_idx
, vhost_avail_event(vq
)))
995 if (unlikely(vq
->log_used
)) {
997 /* Make sure the event is seen before log. */
999 /* Log avail event write */
1000 used
= vhost_avail_event(vq
);
1001 log_write(vq
->log_base
, vq
->log_addr
+
1002 (used
- (void __user
*)vq
->used
),
1003 sizeof *vhost_avail_event(vq
));
1005 eventfd_signal(vq
->log_ctx
, 1);
1010 int vhost_init_used(struct vhost_virtqueue
*vq
)
1013 if (!vq
->private_data
)
1016 r
= vhost_update_used_flags(vq
);
1019 vq
->signalled_used_valid
= false;
1020 return get_user(vq
->last_used_idx
, &vq
->used
->idx
);
1023 static int translate_desc(struct vhost_dev
*dev
, u64 addr
, u32 len
,
1024 struct iovec iov
[], int iov_size
)
1026 const struct vhost_memory_region
*reg
;
1027 struct vhost_memory
*mem
;
1034 mem
= rcu_dereference(dev
->memory
);
1035 while ((u64
)len
> s
) {
1037 if (unlikely(ret
>= iov_size
)) {
1041 reg
= find_region(mem
, addr
, len
);
1042 if (unlikely(!reg
)) {
1047 size
= reg
->memory_size
- addr
+ reg
->guest_phys_addr
;
1048 _iov
->iov_len
= min((u64
)len
- s
, size
);
1049 _iov
->iov_base
= (void __user
*)(unsigned long)
1050 (reg
->userspace_addr
+ addr
- reg
->guest_phys_addr
);
1060 /* Each buffer in the virtqueues is actually a chain of descriptors. This
1061 * function returns the next descriptor in the chain,
1062 * or -1U if we're at the end. */
1063 static unsigned next_desc(struct vring_desc
*desc
)
1067 /* If this descriptor says it doesn't chain, we're done. */
1068 if (!(desc
->flags
& VRING_DESC_F_NEXT
))
1071 /* Check they're not leading us off end of descriptors. */
1073 /* Make sure compiler knows to grab that: we don't want it changing! */
1074 /* We will use the result as an index in an array, so most
1075 * architectures only need a compiler barrier here. */
1076 read_barrier_depends();
1081 static int get_indirect(struct vhost_dev
*dev
, struct vhost_virtqueue
*vq
,
1082 struct iovec iov
[], unsigned int iov_size
,
1083 unsigned int *out_num
, unsigned int *in_num
,
1084 struct vhost_log
*log
, unsigned int *log_num
,
1085 struct vring_desc
*indirect
)
1087 struct vring_desc desc
;
1088 unsigned int i
= 0, count
, found
= 0;
1092 if (unlikely(indirect
->len
% sizeof desc
)) {
1093 vq_err(vq
, "Invalid length in indirect descriptor: "
1094 "len 0x%llx not multiple of 0x%zx\n",
1095 (unsigned long long)indirect
->len
,
1100 ret
= translate_desc(dev
, indirect
->addr
, indirect
->len
, vq
->indirect
,
1102 if (unlikely(ret
< 0)) {
1103 vq_err(vq
, "Translation failure %d in indirect.\n", ret
);
1107 /* We will use the result as an address to read from, so most
1108 * architectures only need a compiler barrier here. */
1109 read_barrier_depends();
1111 count
= indirect
->len
/ sizeof desc
;
1112 /* Buffers are chained via a 16 bit next field, so
1113 * we can have at most 2^16 of these. */
1114 if (unlikely(count
> USHRT_MAX
+ 1)) {
1115 vq_err(vq
, "Indirect buffer length too big: %d\n",
1121 unsigned iov_count
= *in_num
+ *out_num
;
1122 if (unlikely(++found
> count
)) {
1123 vq_err(vq
, "Loop detected: last one at %u "
1124 "indirect size %u\n",
1128 if (unlikely(memcpy_fromiovec((unsigned char *)&desc
,
1129 vq
->indirect
, sizeof desc
))) {
1130 vq_err(vq
, "Failed indirect descriptor: idx %d, %zx\n",
1131 i
, (size_t)indirect
->addr
+ i
* sizeof desc
);
1134 if (unlikely(desc
.flags
& VRING_DESC_F_INDIRECT
)) {
1135 vq_err(vq
, "Nested indirect descriptor: idx %d, %zx\n",
1136 i
, (size_t)indirect
->addr
+ i
* sizeof desc
);
1140 ret
= translate_desc(dev
, desc
.addr
, desc
.len
, iov
+ iov_count
,
1141 iov_size
- iov_count
);
1142 if (unlikely(ret
< 0)) {
1143 vq_err(vq
, "Translation failure %d indirect idx %d\n",
1147 /* If this is an input descriptor, increment that count. */
1148 if (desc
.flags
& VRING_DESC_F_WRITE
) {
1150 if (unlikely(log
)) {
1151 log
[*log_num
].addr
= desc
.addr
;
1152 log
[*log_num
].len
= desc
.len
;
1156 /* If it's an output descriptor, they're all supposed
1157 * to come before any input descriptors. */
1158 if (unlikely(*in_num
)) {
1159 vq_err(vq
, "Indirect descriptor "
1160 "has out after in: idx %d\n", i
);
1165 } while ((i
= next_desc(&desc
)) != -1);
1169 /* This looks in the virtqueue and for the first available buffer, and converts
1170 * it to an iovec for convenient access. Since descriptors consist of some
1171 * number of output then some number of input descriptors, it's actually two
1172 * iovecs, but we pack them into one and note how many of each there were.
1174 * This function returns the descriptor number found, or vq->num (which is
1175 * never a valid descriptor number) if none was found. A negative code is
1176 * returned on error. */
1177 int vhost_get_vq_desc(struct vhost_dev
*dev
, struct vhost_virtqueue
*vq
,
1178 struct iovec iov
[], unsigned int iov_size
,
1179 unsigned int *out_num
, unsigned int *in_num
,
1180 struct vhost_log
*log
, unsigned int *log_num
)
1182 struct vring_desc desc
;
1183 unsigned int i
, head
, found
= 0;
1187 /* Check it isn't doing very strange things with descriptor numbers. */
1188 last_avail_idx
= vq
->last_avail_idx
;
1189 if (unlikely(__get_user(vq
->avail_idx
, &vq
->avail
->idx
))) {
1190 vq_err(vq
, "Failed to access avail idx at %p\n",
1195 if (unlikely((u16
)(vq
->avail_idx
- last_avail_idx
) > vq
->num
)) {
1196 vq_err(vq
, "Guest moved used index from %u to %u",
1197 last_avail_idx
, vq
->avail_idx
);
1201 /* If there's nothing new since last we looked, return invalid. */
1202 if (vq
->avail_idx
== last_avail_idx
)
1205 /* Only get avail ring entries after they have been exposed by guest. */
1208 /* Grab the next descriptor number they're advertising, and increment
1209 * the index we've seen. */
1210 if (unlikely(__get_user(head
,
1211 &vq
->avail
->ring
[last_avail_idx
% vq
->num
]))) {
1212 vq_err(vq
, "Failed to read head: idx %d address %p\n",
1214 &vq
->avail
->ring
[last_avail_idx
% vq
->num
]);
1218 /* If their number is silly, that's an error. */
1219 if (unlikely(head
>= vq
->num
)) {
1220 vq_err(vq
, "Guest says index %u > %u is available",
1225 /* When we start there are none of either input nor output. */
1226 *out_num
= *in_num
= 0;
1232 unsigned iov_count
= *in_num
+ *out_num
;
1233 if (unlikely(i
>= vq
->num
)) {
1234 vq_err(vq
, "Desc index is %u > %u, head = %u",
1238 if (unlikely(++found
> vq
->num
)) {
1239 vq_err(vq
, "Loop detected: last one at %u "
1240 "vq size %u head %u\n",
1244 ret
= __copy_from_user(&desc
, vq
->desc
+ i
, sizeof desc
);
1245 if (unlikely(ret
)) {
1246 vq_err(vq
, "Failed to get descriptor: idx %d addr %p\n",
1250 if (desc
.flags
& VRING_DESC_F_INDIRECT
) {
1251 ret
= get_indirect(dev
, vq
, iov
, iov_size
,
1253 log
, log_num
, &desc
);
1254 if (unlikely(ret
< 0)) {
1255 vq_err(vq
, "Failure detected "
1256 "in indirect descriptor at idx %d\n", i
);
1262 ret
= translate_desc(dev
, desc
.addr
, desc
.len
, iov
+ iov_count
,
1263 iov_size
- iov_count
);
1264 if (unlikely(ret
< 0)) {
1265 vq_err(vq
, "Translation failure %d descriptor idx %d\n",
1269 if (desc
.flags
& VRING_DESC_F_WRITE
) {
1270 /* If this is an input descriptor,
1271 * increment that count. */
1273 if (unlikely(log
)) {
1274 log
[*log_num
].addr
= desc
.addr
;
1275 log
[*log_num
].len
= desc
.len
;
1279 /* If it's an output descriptor, they're all supposed
1280 * to come before any input descriptors. */
1281 if (unlikely(*in_num
)) {
1282 vq_err(vq
, "Descriptor has out after in: "
1288 } while ((i
= next_desc(&desc
)) != -1);
1290 /* On success, increment avail index. */
1291 vq
->last_avail_idx
++;
1293 /* Assume notifications from guest are disabled at this point,
1294 * if they aren't we would need to update avail_event index. */
1295 BUG_ON(!(vq
->used_flags
& VRING_USED_F_NO_NOTIFY
));
1299 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
1300 void vhost_discard_vq_desc(struct vhost_virtqueue
*vq
, int n
)
1302 vq
->last_avail_idx
-= n
;
1305 /* After we've used one of their buffers, we tell them about it. We'll then
1306 * want to notify the guest, using eventfd. */
1307 int vhost_add_used(struct vhost_virtqueue
*vq
, unsigned int head
, int len
)
1309 struct vring_used_elem __user
*used
;
1311 /* The virtqueue contains a ring of used buffers. Get a pointer to the
1312 * next entry in that used ring. */
1313 used
= &vq
->used
->ring
[vq
->last_used_idx
% vq
->num
];
1314 if (__put_user(head
, &used
->id
)) {
1315 vq_err(vq
, "Failed to write used id");
1318 if (__put_user(len
, &used
->len
)) {
1319 vq_err(vq
, "Failed to write used len");
1322 /* Make sure buffer is written before we update index. */
1324 if (__put_user(vq
->last_used_idx
+ 1, &vq
->used
->idx
)) {
1325 vq_err(vq
, "Failed to increment used idx");
1328 if (unlikely(vq
->log_used
)) {
1329 /* Make sure data is seen before log. */
1331 /* Log used ring entry write. */
1332 log_write(vq
->log_base
,
1334 ((void __user
*)used
- (void __user
*)vq
->used
),
1336 /* Log used index update. */
1337 log_write(vq
->log_base
,
1338 vq
->log_addr
+ offsetof(struct vring_used
, idx
),
1339 sizeof vq
->used
->idx
);
1341 eventfd_signal(vq
->log_ctx
, 1);
1343 vq
->last_used_idx
++;
1344 /* If the driver never bothers to signal in a very long while,
1345 * used index might wrap around. If that happens, invalidate
1346 * signalled_used index we stored. TODO: make sure driver
1347 * signals at least once in 2^16 and remove this. */
1348 if (unlikely(vq
->last_used_idx
== vq
->signalled_used
))
1349 vq
->signalled_used_valid
= false;
1353 static int __vhost_add_used_n(struct vhost_virtqueue
*vq
,
1354 struct vring_used_elem
*heads
,
1357 struct vring_used_elem __user
*used
;
1361 start
= vq
->last_used_idx
% vq
->num
;
1362 used
= vq
->used
->ring
+ start
;
1363 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);
1422 static bool vhost_notify(struct vhost_dev
*dev
, struct vhost_virtqueue
*vq
)
1424 __u16 old
, new, event
;
1426 /* Flush out used index updates. This is paired
1427 * with the barrier that the Guest executes when enabling
1431 if (vhost_has_feature(dev
, VIRTIO_F_NOTIFY_ON_EMPTY
) &&
1432 unlikely(vq
->avail_idx
== vq
->last_avail_idx
))
1435 if (!vhost_has_feature(dev
, VIRTIO_RING_F_EVENT_IDX
)) {
1437 if (__get_user(flags
, &vq
->avail
->flags
)) {
1438 vq_err(vq
, "Failed to get flags");
1441 return !(flags
& VRING_AVAIL_F_NO_INTERRUPT
);
1443 old
= vq
->signalled_used
;
1444 v
= vq
->signalled_used_valid
;
1445 new = vq
->signalled_used
= vq
->last_used_idx
;
1446 vq
->signalled_used_valid
= true;
1451 if (get_user(event
, vhost_used_event(vq
))) {
1452 vq_err(vq
, "Failed to get used event idx");
1455 return vring_need_event(event
, new, old
);
1458 /* This actually signals the guest, using eventfd. */
1459 void vhost_signal(struct vhost_dev
*dev
, struct vhost_virtqueue
*vq
)
1461 /* Signal the Guest tell them we used something up. */
1462 if (vq
->call_ctx
&& vhost_notify(dev
, vq
))
1463 eventfd_signal(vq
->call_ctx
, 1);
1466 /* And here's the combo meal deal. Supersize me! */
1467 void vhost_add_used_and_signal(struct vhost_dev
*dev
,
1468 struct vhost_virtqueue
*vq
,
1469 unsigned int head
, int len
)
1471 vhost_add_used(vq
, head
, len
);
1472 vhost_signal(dev
, vq
);
1475 /* multi-buffer version of vhost_add_used_and_signal */
1476 void vhost_add_used_and_signal_n(struct vhost_dev
*dev
,
1477 struct vhost_virtqueue
*vq
,
1478 struct vring_used_elem
*heads
, unsigned count
)
1480 vhost_add_used_n(vq
, heads
, count
);
1481 vhost_signal(dev
, vq
);
1484 /* OK, now we need to know about added descriptors. */
1485 bool vhost_enable_notify(struct vhost_dev
*dev
, struct vhost_virtqueue
*vq
)
1490 if (!(vq
->used_flags
& VRING_USED_F_NO_NOTIFY
))
1492 vq
->used_flags
&= ~VRING_USED_F_NO_NOTIFY
;
1493 if (!vhost_has_feature(dev
, VIRTIO_RING_F_EVENT_IDX
)) {
1494 r
= vhost_update_used_flags(vq
);
1496 vq_err(vq
, "Failed to enable notification at %p: %d\n",
1497 &vq
->used
->flags
, r
);
1501 r
= vhost_update_avail_event(vq
, vq
->avail_idx
);
1503 vq_err(vq
, "Failed to update avail event index at %p: %d\n",
1504 vhost_avail_event(vq
), r
);
1508 /* They could have slipped one in as we were doing that: make
1509 * sure it's written, then check again. */
1511 r
= __get_user(avail_idx
, &vq
->avail
->idx
);
1513 vq_err(vq
, "Failed to check avail idx at %p: %d\n",
1514 &vq
->avail
->idx
, r
);
1518 return avail_idx
!= vq
->avail_idx
;
1521 /* We don't need to be notified again. */
1522 void vhost_disable_notify(struct vhost_dev
*dev
, struct vhost_virtqueue
*vq
)
1526 if (vq
->used_flags
& VRING_USED_F_NO_NOTIFY
)
1528 vq
->used_flags
|= VRING_USED_F_NO_NOTIFY
;
1529 if (!vhost_has_feature(dev
, VIRTIO_RING_F_EVENT_IDX
)) {
1530 r
= vhost_update_used_flags(vq
);
1532 vq_err(vq
, "Failed to enable notification at %p: %d\n",
1533 &vq
->used
->flags
, r
);