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/virtio_net.h>
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 static unsigned vhost_zcopy_mask __read_mostly
;
38 #define vhost_used_event(vq) ((u16 __user *)&vq->avail->ring[vq->num])
39 #define vhost_avail_event(vq) ((u16 __user *)&vq->used->ring[vq->num])
41 static void vhost_poll_func(struct file
*file
, wait_queue_head_t
*wqh
,
44 struct vhost_poll
*poll
;
46 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 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
)
90 mask
= file
->f_op
->poll(file
, &poll
->table
);
92 vhost_poll_wakeup(&poll
->wait
, 0, 0, (void *)mask
);
95 /* Stop polling a file. After this function returns, it becomes safe to drop the
96 * file reference. You must also flush afterwards. */
97 void vhost_poll_stop(struct vhost_poll
*poll
)
99 remove_wait_queue(poll
->wqh
, &poll
->wait
);
102 static bool vhost_work_seq_done(struct vhost_dev
*dev
, struct vhost_work
*work
,
107 spin_lock_irq(&dev
->work_lock
);
108 left
= seq
- work
->done_seq
;
109 spin_unlock_irq(&dev
->work_lock
);
113 static void vhost_work_flush(struct vhost_dev
*dev
, struct vhost_work
*work
)
118 spin_lock_irq(&dev
->work_lock
);
119 seq
= work
->queue_seq
;
121 spin_unlock_irq(&dev
->work_lock
);
122 wait_event(work
->done
, vhost_work_seq_done(dev
, work
, seq
));
123 spin_lock_irq(&dev
->work_lock
);
124 flushing
= --work
->flushing
;
125 spin_unlock_irq(&dev
->work_lock
);
126 BUG_ON(flushing
< 0);
129 /* Flush any work that has been scheduled. When calling this, don't hold any
130 * locks that are also used by the callback. */
131 void vhost_poll_flush(struct vhost_poll
*poll
)
133 vhost_work_flush(poll
->dev
, &poll
->work
);
136 void vhost_work_queue(struct vhost_dev
*dev
, struct vhost_work
*work
)
140 spin_lock_irqsave(&dev
->work_lock
, flags
);
141 if (list_empty(&work
->node
)) {
142 list_add_tail(&work
->node
, &dev
->work_list
);
144 wake_up_process(dev
->worker
);
146 spin_unlock_irqrestore(&dev
->work_lock
, flags
);
149 void vhost_poll_queue(struct vhost_poll
*poll
)
151 vhost_work_queue(poll
->dev
, &poll
->work
);
154 static void vhost_vq_reset(struct vhost_dev
*dev
,
155 struct vhost_virtqueue
*vq
)
161 vq
->last_avail_idx
= 0;
163 vq
->last_used_idx
= 0;
164 vq
->signalled_used
= 0;
165 vq
->signalled_used_valid
= false;
167 vq
->log_used
= false;
168 vq
->log_addr
= -1ull;
171 vq
->private_data
= NULL
;
173 vq
->error_ctx
= NULL
;
184 static int vhost_worker(void *data
)
186 struct vhost_dev
*dev
= data
;
187 struct vhost_work
*work
= NULL
;
188 unsigned uninitialized_var(seq
);
189 mm_segment_t oldfs
= get_fs();
195 /* mb paired w/ kthread_stop */
196 set_current_state(TASK_INTERRUPTIBLE
);
198 spin_lock_irq(&dev
->work_lock
);
200 work
->done_seq
= seq
;
202 wake_up_all(&work
->done
);
205 if (kthread_should_stop()) {
206 spin_unlock_irq(&dev
->work_lock
);
207 __set_current_state(TASK_RUNNING
);
210 if (!list_empty(&dev
->work_list
)) {
211 work
= list_first_entry(&dev
->work_list
,
212 struct vhost_work
, node
);
213 list_del_init(&work
->node
);
214 seq
= work
->queue_seq
;
217 spin_unlock_irq(&dev
->work_lock
);
220 __set_current_state(TASK_RUNNING
);
233 static void vhost_vq_free_iovecs(struct vhost_virtqueue
*vq
)
241 kfree(vq
->ubuf_info
);
242 vq
->ubuf_info
= NULL
;
245 void vhost_enable_zcopy(int vq
)
247 vhost_zcopy_mask
|= 0x1 << vq
;
250 /* Helper to allocate iovec buffers for all vqs. */
251 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 zcopy
= vhost_zcopy_mask
& (0x1 << i
);
265 dev
->vqs
[i
].ubuf_info
=
266 kmalloc(sizeof *dev
->vqs
[i
].ubuf_info
*
267 UIO_MAXIOV
, GFP_KERNEL
);
268 if (!dev
->vqs
[i
].indirect
|| !dev
->vqs
[i
].log
||
269 !dev
->vqs
[i
].heads
||
270 (zcopy
&& !dev
->vqs
[i
].ubuf_info
))
277 vhost_vq_free_iovecs(&dev
->vqs
[i
]);
281 static void vhost_dev_free_iovecs(struct vhost_dev
*dev
)
285 for (i
= 0; i
< dev
->nvqs
; ++i
)
286 vhost_vq_free_iovecs(&dev
->vqs
[i
]);
289 long vhost_dev_init(struct vhost_dev
*dev
,
290 struct vhost_virtqueue
*vqs
, int nvqs
)
296 mutex_init(&dev
->mutex
);
298 dev
->log_file
= NULL
;
301 spin_lock_init(&dev
->work_lock
);
302 INIT_LIST_HEAD(&dev
->work_list
);
305 for (i
= 0; i
< dev
->nvqs
; ++i
) {
306 dev
->vqs
[i
].log
= NULL
;
307 dev
->vqs
[i
].indirect
= NULL
;
308 dev
->vqs
[i
].heads
= NULL
;
309 dev
->vqs
[i
].ubuf_info
= NULL
;
310 dev
->vqs
[i
].dev
= dev
;
311 mutex_init(&dev
->vqs
[i
].mutex
);
312 vhost_vq_reset(dev
, dev
->vqs
+ i
);
313 if (dev
->vqs
[i
].handle_kick
)
314 vhost_poll_init(&dev
->vqs
[i
].poll
,
315 dev
->vqs
[i
].handle_kick
, POLLIN
, dev
);
321 /* Caller should have device mutex */
322 long vhost_dev_check_owner(struct vhost_dev
*dev
)
324 /* Are you the owner? If not, I don't think you mean to do that */
325 return dev
->mm
== current
->mm
? 0 : -EPERM
;
328 struct vhost_attach_cgroups_struct
{
329 struct vhost_work work
;
330 struct task_struct
*owner
;
334 static void vhost_attach_cgroups_work(struct vhost_work
*work
)
336 struct vhost_attach_cgroups_struct
*s
;
338 s
= container_of(work
, struct vhost_attach_cgroups_struct
, work
);
339 s
->ret
= cgroup_attach_task_all(s
->owner
, current
);
342 static int vhost_attach_cgroups(struct vhost_dev
*dev
)
344 struct vhost_attach_cgroups_struct attach
;
346 attach
.owner
= current
;
347 vhost_work_init(&attach
.work
, vhost_attach_cgroups_work
);
348 vhost_work_queue(dev
, &attach
.work
);
349 vhost_work_flush(dev
, &attach
.work
);
353 /* Caller should have device mutex */
354 static long vhost_dev_set_owner(struct vhost_dev
*dev
)
356 struct task_struct
*worker
;
359 /* Is there an owner already? */
365 /* No owner, become one */
366 dev
->mm
= get_task_mm(current
);
367 worker
= kthread_create(vhost_worker
, dev
, "vhost-%d", current
->pid
);
368 if (IS_ERR(worker
)) {
369 err
= PTR_ERR(worker
);
373 dev
->worker
= worker
;
374 wake_up_process(worker
); /* avoid contributing to loadavg */
376 err
= vhost_attach_cgroups(dev
);
380 err
= vhost_dev_alloc_iovecs(dev
);
386 kthread_stop(worker
);
396 /* Caller should have device mutex */
397 long vhost_dev_reset_owner(struct vhost_dev
*dev
)
399 struct vhost_memory
*memory
;
401 /* Restore memory to default empty mapping. */
402 memory
= kmalloc(offsetof(struct vhost_memory
, regions
), GFP_KERNEL
);
406 vhost_dev_cleanup(dev
, true);
408 memory
->nregions
= 0;
409 RCU_INIT_POINTER(dev
->memory
, memory
);
413 void vhost_dev_stop(struct vhost_dev
*dev
)
417 for (i
= 0; i
< dev
->nvqs
; ++i
) {
418 if (dev
->vqs
[i
].kick
&& dev
->vqs
[i
].handle_kick
) {
419 vhost_poll_stop(&dev
->vqs
[i
].poll
);
420 vhost_poll_flush(&dev
->vqs
[i
].poll
);
425 /* Caller should have device mutex if and only if locked is set */
426 void vhost_dev_cleanup(struct vhost_dev
*dev
, bool locked
)
430 for (i
= 0; i
< dev
->nvqs
; ++i
) {
431 if (dev
->vqs
[i
].error_ctx
)
432 eventfd_ctx_put(dev
->vqs
[i
].error_ctx
);
433 if (dev
->vqs
[i
].error
)
434 fput(dev
->vqs
[i
].error
);
435 if (dev
->vqs
[i
].kick
)
436 fput(dev
->vqs
[i
].kick
);
437 if (dev
->vqs
[i
].call_ctx
)
438 eventfd_ctx_put(dev
->vqs
[i
].call_ctx
);
439 if (dev
->vqs
[i
].call
)
440 fput(dev
->vqs
[i
].call
);
441 vhost_vq_reset(dev
, dev
->vqs
+ i
);
443 vhost_dev_free_iovecs(dev
);
445 eventfd_ctx_put(dev
->log_ctx
);
449 dev
->log_file
= NULL
;
450 /* No one will access memory at this point */
451 kfree(rcu_dereference_protected(dev
->memory
,
453 lockdep_is_held(&dev
->mutex
)));
454 RCU_INIT_POINTER(dev
->memory
, NULL
);
455 WARN_ON(!list_empty(&dev
->work_list
));
457 kthread_stop(dev
->worker
);
465 static int log_access_ok(void __user
*log_base
, u64 addr
, unsigned long sz
)
467 u64 a
= addr
/ VHOST_PAGE_SIZE
/ 8;
469 /* Make sure 64 bit math will not overflow. */
470 if (a
> ULONG_MAX
- (unsigned long)log_base
||
471 a
+ (unsigned long)log_base
> ULONG_MAX
)
474 return access_ok(VERIFY_WRITE
, log_base
+ a
,
475 (sz
+ VHOST_PAGE_SIZE
* 8 - 1) / VHOST_PAGE_SIZE
/ 8);
478 /* Caller should have vq mutex and device mutex. */
479 static int vq_memory_access_ok(void __user
*log_base
, struct vhost_memory
*mem
,
487 for (i
= 0; i
< mem
->nregions
; ++i
) {
488 struct vhost_memory_region
*m
= mem
->regions
+ i
;
489 unsigned long a
= m
->userspace_addr
;
490 if (m
->memory_size
> ULONG_MAX
)
492 else if (!access_ok(VERIFY_WRITE
, (void __user
*)a
,
495 else if (log_all
&& !log_access_ok(log_base
,
503 /* Can we switch to this memory table? */
504 /* Caller should have device mutex but not vq mutex */
505 static int memory_access_ok(struct vhost_dev
*d
, struct vhost_memory
*mem
,
510 for (i
= 0; i
< d
->nvqs
; ++i
) {
512 mutex_lock(&d
->vqs
[i
].mutex
);
513 /* If ring is inactive, will check when it's enabled. */
514 if (d
->vqs
[i
].private_data
)
515 ok
= vq_memory_access_ok(d
->vqs
[i
].log_base
, mem
,
519 mutex_unlock(&d
->vqs
[i
].mutex
);
526 static int vq_access_ok(struct vhost_dev
*d
, unsigned int num
,
527 struct vring_desc __user
*desc
,
528 struct vring_avail __user
*avail
,
529 struct vring_used __user
*used
)
531 size_t s
= vhost_has_feature(d
, VIRTIO_RING_F_EVENT_IDX
) ? 2 : 0;
532 return access_ok(VERIFY_READ
, desc
, num
* sizeof *desc
) &&
533 access_ok(VERIFY_READ
, avail
,
534 sizeof *avail
+ num
* sizeof *avail
->ring
+ s
) &&
535 access_ok(VERIFY_WRITE
, used
,
536 sizeof *used
+ num
* sizeof *used
->ring
+ s
);
539 /* Can we log writes? */
540 /* Caller should have device mutex but not vq mutex */
541 int vhost_log_access_ok(struct vhost_dev
*dev
)
543 struct vhost_memory
*mp
;
545 mp
= rcu_dereference_protected(dev
->memory
,
546 lockdep_is_held(&dev
->mutex
));
547 return memory_access_ok(dev
, mp
, 1);
550 /* Verify access for write logging. */
551 /* Caller should have vq mutex and device mutex */
552 static int vq_log_access_ok(struct vhost_dev
*d
, struct vhost_virtqueue
*vq
,
553 void __user
*log_base
)
555 struct vhost_memory
*mp
;
556 size_t s
= vhost_has_feature(d
, VIRTIO_RING_F_EVENT_IDX
) ? 2 : 0;
558 mp
= rcu_dereference_protected(vq
->dev
->memory
,
559 lockdep_is_held(&vq
->mutex
));
560 return vq_memory_access_ok(log_base
, mp
,
561 vhost_has_feature(vq
->dev
, VHOST_F_LOG_ALL
)) &&
562 (!vq
->log_used
|| log_access_ok(log_base
, vq
->log_addr
,
564 vq
->num
* sizeof *vq
->used
->ring
+ s
));
567 /* Can we start vq? */
568 /* Caller should have vq mutex and device mutex */
569 int vhost_vq_access_ok(struct vhost_virtqueue
*vq
)
571 return vq_access_ok(vq
->dev
, vq
->num
, vq
->desc
, vq
->avail
, vq
->used
) &&
572 vq_log_access_ok(vq
->dev
, vq
, vq
->log_base
);
575 static long vhost_set_memory(struct vhost_dev
*d
, struct vhost_memory __user
*m
)
577 struct vhost_memory mem
, *newmem
, *oldmem
;
578 unsigned long size
= offsetof(struct vhost_memory
, regions
);
580 if (copy_from_user(&mem
, m
, size
))
584 if (mem
.nregions
> VHOST_MEMORY_MAX_NREGIONS
)
586 newmem
= kmalloc(size
+ mem
.nregions
* sizeof *m
->regions
, GFP_KERNEL
);
590 memcpy(newmem
, &mem
, size
);
591 if (copy_from_user(newmem
->regions
, m
->regions
,
592 mem
.nregions
* sizeof *m
->regions
)) {
597 if (!memory_access_ok(d
, newmem
,
598 vhost_has_feature(d
, VHOST_F_LOG_ALL
))) {
602 oldmem
= rcu_dereference_protected(d
->memory
,
603 lockdep_is_held(&d
->mutex
));
604 rcu_assign_pointer(d
->memory
, newmem
);
610 long vhost_vring_ioctl(struct vhost_dev
*d
, int ioctl
, void __user
*argp
)
612 struct file
*eventfp
, *filep
= NULL
;
613 bool pollstart
= false, pollstop
= false;
614 struct eventfd_ctx
*ctx
= NULL
;
615 u32 __user
*idxp
= argp
;
616 struct vhost_virtqueue
*vq
;
617 struct vhost_vring_state s
;
618 struct vhost_vring_file f
;
619 struct vhost_vring_addr a
;
623 r
= get_user(idx
, idxp
);
631 mutex_lock(&vq
->mutex
);
634 case VHOST_SET_VRING_NUM
:
635 /* Resizing ring with an active backend?
636 * You don't want to do that. */
637 if (vq
->private_data
) {
641 if (copy_from_user(&s
, argp
, sizeof s
)) {
645 if (!s
.num
|| s
.num
> 0xffff || (s
.num
& (s
.num
- 1))) {
651 case VHOST_SET_VRING_BASE
:
652 /* Moving base with an active backend?
653 * You don't want to do that. */
654 if (vq
->private_data
) {
658 if (copy_from_user(&s
, argp
, sizeof s
)) {
662 if (s
.num
> 0xffff) {
666 vq
->last_avail_idx
= s
.num
;
667 /* Forget the cached index value. */
668 vq
->avail_idx
= vq
->last_avail_idx
;
670 case VHOST_GET_VRING_BASE
:
672 s
.num
= vq
->last_avail_idx
;
673 if (copy_to_user(argp
, &s
, sizeof s
))
676 case VHOST_SET_VRING_ADDR
:
677 if (copy_from_user(&a
, argp
, sizeof a
)) {
681 if (a
.flags
& ~(0x1 << VHOST_VRING_F_LOG
)) {
685 /* For 32bit, verify that the top 32bits of the user
686 data are set to zero. */
687 if ((u64
)(unsigned long)a
.desc_user_addr
!= a
.desc_user_addr
||
688 (u64
)(unsigned long)a
.used_user_addr
!= a
.used_user_addr
||
689 (u64
)(unsigned long)a
.avail_user_addr
!= a
.avail_user_addr
) {
693 if ((a
.avail_user_addr
& (sizeof *vq
->avail
->ring
- 1)) ||
694 (a
.used_user_addr
& (sizeof *vq
->used
->ring
- 1)) ||
695 (a
.log_guest_addr
& (sizeof *vq
->used
->ring
- 1))) {
700 /* We only verify access here if backend is configured.
701 * If it is not, we don't as size might not have been setup.
702 * We will verify when backend is configured. */
703 if (vq
->private_data
) {
704 if (!vq_access_ok(d
, vq
->num
,
705 (void __user
*)(unsigned long)a
.desc_user_addr
,
706 (void __user
*)(unsigned long)a
.avail_user_addr
,
707 (void __user
*)(unsigned long)a
.used_user_addr
)) {
712 /* Also validate log access for used ring if enabled. */
713 if ((a
.flags
& (0x1 << VHOST_VRING_F_LOG
)) &&
714 !log_access_ok(vq
->log_base
, a
.log_guest_addr
,
716 vq
->num
* sizeof *vq
->used
->ring
)) {
722 vq
->log_used
= !!(a
.flags
& (0x1 << VHOST_VRING_F_LOG
));
723 vq
->desc
= (void __user
*)(unsigned long)a
.desc_user_addr
;
724 vq
->avail
= (void __user
*)(unsigned long)a
.avail_user_addr
;
725 vq
->log_addr
= a
.log_guest_addr
;
726 vq
->used
= (void __user
*)(unsigned long)a
.used_user_addr
;
728 case VHOST_SET_VRING_KICK
:
729 if (copy_from_user(&f
, argp
, sizeof f
)) {
733 eventfp
= f
.fd
== -1 ? NULL
: eventfd_fget(f
.fd
);
734 if (IS_ERR(eventfp
)) {
735 r
= PTR_ERR(eventfp
);
738 if (eventfp
!= vq
->kick
) {
739 pollstop
= (filep
= vq
->kick
) != NULL
;
740 pollstart
= (vq
->kick
= eventfp
) != NULL
;
744 case VHOST_SET_VRING_CALL
:
745 if (copy_from_user(&f
, argp
, sizeof f
)) {
749 eventfp
= f
.fd
== -1 ? NULL
: eventfd_fget(f
.fd
);
750 if (IS_ERR(eventfp
)) {
751 r
= PTR_ERR(eventfp
);
754 if (eventfp
!= vq
->call
) {
758 vq
->call_ctx
= eventfp
?
759 eventfd_ctx_fileget(eventfp
) : NULL
;
763 case VHOST_SET_VRING_ERR
:
764 if (copy_from_user(&f
, argp
, sizeof f
)) {
768 eventfp
= f
.fd
== -1 ? NULL
: eventfd_fget(f
.fd
);
769 if (IS_ERR(eventfp
)) {
770 r
= PTR_ERR(eventfp
);
773 if (eventfp
!= vq
->error
) {
777 vq
->error_ctx
= eventfp
?
778 eventfd_ctx_fileget(eventfp
) : NULL
;
786 if (pollstop
&& vq
->handle_kick
)
787 vhost_poll_stop(&vq
->poll
);
790 eventfd_ctx_put(ctx
);
794 if (pollstart
&& vq
->handle_kick
)
795 vhost_poll_start(&vq
->poll
, vq
->kick
);
797 mutex_unlock(&vq
->mutex
);
799 if (pollstop
&& vq
->handle_kick
)
800 vhost_poll_flush(&vq
->poll
);
804 /* Caller must have device mutex */
805 long vhost_dev_ioctl(struct vhost_dev
*d
, unsigned int ioctl
, void __user
*argp
)
807 struct file
*eventfp
, *filep
= NULL
;
808 struct eventfd_ctx
*ctx
= NULL
;
813 /* If you are not the owner, you can become one */
814 if (ioctl
== VHOST_SET_OWNER
) {
815 r
= vhost_dev_set_owner(d
);
819 /* You must be the owner to do anything else */
820 r
= vhost_dev_check_owner(d
);
825 case VHOST_SET_MEM_TABLE
:
826 r
= vhost_set_memory(d
, argp
);
828 case VHOST_SET_LOG_BASE
:
829 if (copy_from_user(&p
, argp
, sizeof p
)) {
833 if ((u64
)(unsigned long)p
!= p
) {
837 for (i
= 0; i
< d
->nvqs
; ++i
) {
838 struct vhost_virtqueue
*vq
;
839 void __user
*base
= (void __user
*)(unsigned long)p
;
841 mutex_lock(&vq
->mutex
);
842 /* If ring is inactive, will check when it's enabled. */
843 if (vq
->private_data
&& !vq_log_access_ok(d
, vq
, base
))
847 mutex_unlock(&vq
->mutex
);
850 case VHOST_SET_LOG_FD
:
851 r
= get_user(fd
, (int __user
*)argp
);
854 eventfp
= fd
== -1 ? NULL
: eventfd_fget(fd
);
855 if (IS_ERR(eventfp
)) {
856 r
= PTR_ERR(eventfp
);
859 if (eventfp
!= d
->log_file
) {
862 d
->log_ctx
= eventfp
?
863 eventfd_ctx_fileget(eventfp
) : NULL
;
866 for (i
= 0; i
< d
->nvqs
; ++i
) {
867 mutex_lock(&d
->vqs
[i
].mutex
);
868 d
->vqs
[i
].log_ctx
= d
->log_ctx
;
869 mutex_unlock(&d
->vqs
[i
].mutex
);
872 eventfd_ctx_put(ctx
);
884 static const struct vhost_memory_region
*find_region(struct vhost_memory
*mem
,
885 __u64 addr
, __u32 len
)
887 struct vhost_memory_region
*reg
;
890 /* linear search is not brilliant, but we really have on the order of 6
891 * regions in practice */
892 for (i
= 0; i
< mem
->nregions
; ++i
) {
893 reg
= mem
->regions
+ i
;
894 if (reg
->guest_phys_addr
<= addr
&&
895 reg
->guest_phys_addr
+ reg
->memory_size
- 1 >= addr
)
901 /* TODO: This is really inefficient. We need something like get_user()
902 * (instruction directly accesses the data, with an exception table entry
903 * returning -EFAULT). See Documentation/x86/exception-tables.txt.
905 static int set_bit_to_user(int nr
, void __user
*addr
)
907 unsigned long log
= (unsigned long)addr
;
910 int bit
= nr
+ (log
% PAGE_SIZE
) * 8;
913 r
= get_user_pages_fast(log
, 1, 1, &page
);
917 base
= kmap_atomic(page
);
920 set_page_dirty_lock(page
);
925 static int log_write(void __user
*log_base
,
926 u64 write_address
, u64 write_length
)
928 u64 write_page
= write_address
/ VHOST_PAGE_SIZE
;
933 write_length
+= write_address
% VHOST_PAGE_SIZE
;
935 u64 base
= (u64
)(unsigned long)log_base
;
936 u64 log
= base
+ write_page
/ 8;
937 int bit
= write_page
% 8;
938 if ((u64
)(unsigned long)log
!= log
)
940 r
= set_bit_to_user(bit
, (void __user
*)(unsigned long)log
);
943 if (write_length
<= VHOST_PAGE_SIZE
)
945 write_length
-= VHOST_PAGE_SIZE
;
951 int vhost_log_write(struct vhost_virtqueue
*vq
, struct vhost_log
*log
,
952 unsigned int log_num
, u64 len
)
956 /* Make sure data written is seen before log. */
958 for (i
= 0; i
< log_num
; ++i
) {
959 u64 l
= min(log
[i
].len
, len
);
960 r
= log_write(vq
->log_base
, log
[i
].addr
, l
);
966 eventfd_signal(vq
->log_ctx
, 1);
970 /* Length written exceeds what we have stored. This is a bug. */
975 static int vhost_update_used_flags(struct vhost_virtqueue
*vq
)
978 if (__put_user(vq
->used_flags
, &vq
->used
->flags
) < 0)
980 if (unlikely(vq
->log_used
)) {
981 /* Make sure the flag is seen before log. */
983 /* Log used flag write. */
984 used
= &vq
->used
->flags
;
985 log_write(vq
->log_base
, vq
->log_addr
+
986 (used
- (void __user
*)vq
->used
),
987 sizeof vq
->used
->flags
);
989 eventfd_signal(vq
->log_ctx
, 1);
994 static int vhost_update_avail_event(struct vhost_virtqueue
*vq
, u16 avail_event
)
996 if (__put_user(vq
->avail_idx
, vhost_avail_event(vq
)))
998 if (unlikely(vq
->log_used
)) {
1000 /* Make sure the event is seen before log. */
1002 /* Log avail event write */
1003 used
= vhost_avail_event(vq
);
1004 log_write(vq
->log_base
, vq
->log_addr
+
1005 (used
- (void __user
*)vq
->used
),
1006 sizeof *vhost_avail_event(vq
));
1008 eventfd_signal(vq
->log_ctx
, 1);
1013 int vhost_init_used(struct vhost_virtqueue
*vq
)
1016 if (!vq
->private_data
)
1019 r
= vhost_update_used_flags(vq
);
1022 vq
->signalled_used_valid
= false;
1023 return get_user(vq
->last_used_idx
, &vq
->used
->idx
);
1026 static int translate_desc(struct vhost_dev
*dev
, u64 addr
, u32 len
,
1027 struct iovec iov
[], int iov_size
)
1029 const struct vhost_memory_region
*reg
;
1030 struct vhost_memory
*mem
;
1037 mem
= rcu_dereference(dev
->memory
);
1038 while ((u64
)len
> s
) {
1040 if (unlikely(ret
>= iov_size
)) {
1044 reg
= find_region(mem
, addr
, len
);
1045 if (unlikely(!reg
)) {
1050 size
= reg
->memory_size
- addr
+ reg
->guest_phys_addr
;
1051 _iov
->iov_len
= min((u64
)len
- s
, size
);
1052 _iov
->iov_base
= (void __user
*)(unsigned long)
1053 (reg
->userspace_addr
+ addr
- reg
->guest_phys_addr
);
1063 /* Each buffer in the virtqueues is actually a chain of descriptors. This
1064 * function returns the next descriptor in the chain,
1065 * or -1U if we're at the end. */
1066 static unsigned next_desc(struct vring_desc
*desc
)
1070 /* If this descriptor says it doesn't chain, we're done. */
1071 if (!(desc
->flags
& VRING_DESC_F_NEXT
))
1074 /* Check they're not leading us off end of descriptors. */
1076 /* Make sure compiler knows to grab that: we don't want it changing! */
1077 /* We will use the result as an index in an array, so most
1078 * architectures only need a compiler barrier here. */
1079 read_barrier_depends();
1084 static int get_indirect(struct vhost_dev
*dev
, struct vhost_virtqueue
*vq
,
1085 struct iovec iov
[], unsigned int iov_size
,
1086 unsigned int *out_num
, unsigned int *in_num
,
1087 struct vhost_log
*log
, unsigned int *log_num
,
1088 struct vring_desc
*indirect
)
1090 struct vring_desc desc
;
1091 unsigned int i
= 0, count
, found
= 0;
1095 if (unlikely(indirect
->len
% sizeof desc
)) {
1096 vq_err(vq
, "Invalid length in indirect descriptor: "
1097 "len 0x%llx not multiple of 0x%zx\n",
1098 (unsigned long long)indirect
->len
,
1103 ret
= translate_desc(dev
, indirect
->addr
, indirect
->len
, vq
->indirect
,
1105 if (unlikely(ret
< 0)) {
1106 vq_err(vq
, "Translation failure %d in indirect.\n", ret
);
1110 /* We will use the result as an address to read from, so most
1111 * architectures only need a compiler barrier here. */
1112 read_barrier_depends();
1114 count
= indirect
->len
/ sizeof desc
;
1115 /* Buffers are chained via a 16 bit next field, so
1116 * we can have at most 2^16 of these. */
1117 if (unlikely(count
> USHRT_MAX
+ 1)) {
1118 vq_err(vq
, "Indirect buffer length too big: %d\n",
1124 unsigned iov_count
= *in_num
+ *out_num
;
1125 if (unlikely(++found
> count
)) {
1126 vq_err(vq
, "Loop detected: last one at %u "
1127 "indirect size %u\n",
1131 if (unlikely(memcpy_fromiovec((unsigned char *)&desc
,
1132 vq
->indirect
, sizeof desc
))) {
1133 vq_err(vq
, "Failed indirect descriptor: idx %d, %zx\n",
1134 i
, (size_t)indirect
->addr
+ i
* sizeof desc
);
1137 if (unlikely(desc
.flags
& VRING_DESC_F_INDIRECT
)) {
1138 vq_err(vq
, "Nested indirect descriptor: idx %d, %zx\n",
1139 i
, (size_t)indirect
->addr
+ i
* sizeof desc
);
1143 ret
= translate_desc(dev
, desc
.addr
, desc
.len
, iov
+ iov_count
,
1144 iov_size
- iov_count
);
1145 if (unlikely(ret
< 0)) {
1146 vq_err(vq
, "Translation failure %d indirect idx %d\n",
1150 /* If this is an input descriptor, increment that count. */
1151 if (desc
.flags
& VRING_DESC_F_WRITE
) {
1153 if (unlikely(log
)) {
1154 log
[*log_num
].addr
= desc
.addr
;
1155 log
[*log_num
].len
= desc
.len
;
1159 /* If it's an output descriptor, they're all supposed
1160 * to come before any input descriptors. */
1161 if (unlikely(*in_num
)) {
1162 vq_err(vq
, "Indirect descriptor "
1163 "has out after in: idx %d\n", i
);
1168 } while ((i
= next_desc(&desc
)) != -1);
1172 /* This looks in the virtqueue and for the first available buffer, and converts
1173 * it to an iovec for convenient access. Since descriptors consist of some
1174 * number of output then some number of input descriptors, it's actually two
1175 * iovecs, but we pack them into one and note how many of each there were.
1177 * This function returns the descriptor number found, or vq->num (which is
1178 * never a valid descriptor number) if none was found. A negative code is
1179 * returned on error. */
1180 int vhost_get_vq_desc(struct vhost_dev
*dev
, struct vhost_virtqueue
*vq
,
1181 struct iovec iov
[], unsigned int iov_size
,
1182 unsigned int *out_num
, unsigned int *in_num
,
1183 struct vhost_log
*log
, unsigned int *log_num
)
1185 struct vring_desc desc
;
1186 unsigned int i
, head
, found
= 0;
1190 /* Check it isn't doing very strange things with descriptor numbers. */
1191 last_avail_idx
= vq
->last_avail_idx
;
1192 if (unlikely(__get_user(vq
->avail_idx
, &vq
->avail
->idx
))) {
1193 vq_err(vq
, "Failed to access avail idx at %p\n",
1198 if (unlikely((u16
)(vq
->avail_idx
- last_avail_idx
) > vq
->num
)) {
1199 vq_err(vq
, "Guest moved used index from %u to %u",
1200 last_avail_idx
, vq
->avail_idx
);
1204 /* If there's nothing new since last we looked, return invalid. */
1205 if (vq
->avail_idx
== last_avail_idx
)
1208 /* Only get avail ring entries after they have been exposed by guest. */
1211 /* Grab the next descriptor number they're advertising, and increment
1212 * the index we've seen. */
1213 if (unlikely(__get_user(head
,
1214 &vq
->avail
->ring
[last_avail_idx
% vq
->num
]))) {
1215 vq_err(vq
, "Failed to read head: idx %d address %p\n",
1217 &vq
->avail
->ring
[last_avail_idx
% vq
->num
]);
1221 /* If their number is silly, that's an error. */
1222 if (unlikely(head
>= vq
->num
)) {
1223 vq_err(vq
, "Guest says index %u > %u is available",
1228 /* When we start there are none of either input nor output. */
1229 *out_num
= *in_num
= 0;
1235 unsigned iov_count
= *in_num
+ *out_num
;
1236 if (unlikely(i
>= vq
->num
)) {
1237 vq_err(vq
, "Desc index is %u > %u, head = %u",
1241 if (unlikely(++found
> vq
->num
)) {
1242 vq_err(vq
, "Loop detected: last one at %u "
1243 "vq size %u head %u\n",
1247 ret
= __copy_from_user(&desc
, vq
->desc
+ i
, sizeof desc
);
1248 if (unlikely(ret
)) {
1249 vq_err(vq
, "Failed to get descriptor: idx %d addr %p\n",
1253 if (desc
.flags
& VRING_DESC_F_INDIRECT
) {
1254 ret
= get_indirect(dev
, vq
, iov
, iov_size
,
1256 log
, log_num
, &desc
);
1257 if (unlikely(ret
< 0)) {
1258 vq_err(vq
, "Failure detected "
1259 "in indirect descriptor at idx %d\n", i
);
1265 ret
= translate_desc(dev
, desc
.addr
, desc
.len
, iov
+ iov_count
,
1266 iov_size
- iov_count
);
1267 if (unlikely(ret
< 0)) {
1268 vq_err(vq
, "Translation failure %d descriptor idx %d\n",
1272 if (desc
.flags
& VRING_DESC_F_WRITE
) {
1273 /* If this is an input descriptor,
1274 * increment that count. */
1276 if (unlikely(log
)) {
1277 log
[*log_num
].addr
= desc
.addr
;
1278 log
[*log_num
].len
= desc
.len
;
1282 /* If it's an output descriptor, they're all supposed
1283 * to come before any input descriptors. */
1284 if (unlikely(*in_num
)) {
1285 vq_err(vq
, "Descriptor has out after in: "
1291 } while ((i
= next_desc(&desc
)) != -1);
1293 /* On success, increment avail index. */
1294 vq
->last_avail_idx
++;
1296 /* Assume notifications from guest are disabled at this point,
1297 * if they aren't we would need to update avail_event index. */
1298 BUG_ON(!(vq
->used_flags
& VRING_USED_F_NO_NOTIFY
));
1302 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
1303 void vhost_discard_vq_desc(struct vhost_virtqueue
*vq
, int n
)
1305 vq
->last_avail_idx
-= n
;
1308 /* After we've used one of their buffers, we tell them about it. We'll then
1309 * want to notify the guest, using eventfd. */
1310 int vhost_add_used(struct vhost_virtqueue
*vq
, unsigned int head
, int len
)
1312 struct vring_used_elem __user
*used
;
1314 /* The virtqueue contains a ring of used buffers. Get a pointer to the
1315 * next entry in that used ring. */
1316 used
= &vq
->used
->ring
[vq
->last_used_idx
% vq
->num
];
1317 if (__put_user(head
, &used
->id
)) {
1318 vq_err(vq
, "Failed to write used id");
1321 if (__put_user(len
, &used
->len
)) {
1322 vq_err(vq
, "Failed to write used len");
1325 /* Make sure buffer is written before we update index. */
1327 if (__put_user(vq
->last_used_idx
+ 1, &vq
->used
->idx
)) {
1328 vq_err(vq
, "Failed to increment used idx");
1331 if (unlikely(vq
->log_used
)) {
1332 /* Make sure data is seen before log. */
1334 /* Log used ring entry write. */
1335 log_write(vq
->log_base
,
1337 ((void __user
*)used
- (void __user
*)vq
->used
),
1339 /* Log used index update. */
1340 log_write(vq
->log_base
,
1341 vq
->log_addr
+ offsetof(struct vring_used
, idx
),
1342 sizeof vq
->used
->idx
);
1344 eventfd_signal(vq
->log_ctx
, 1);
1346 vq
->last_used_idx
++;
1347 /* If the driver never bothers to signal in a very long while,
1348 * used index might wrap around. If that happens, invalidate
1349 * signalled_used index we stored. TODO: make sure driver
1350 * signals at least once in 2^16 and remove this. */
1351 if (unlikely(vq
->last_used_idx
== vq
->signalled_used
))
1352 vq
->signalled_used_valid
= false;
1356 static int __vhost_add_used_n(struct vhost_virtqueue
*vq
,
1357 struct vring_used_elem
*heads
,
1360 struct vring_used_elem __user
*used
;
1364 start
= vq
->last_used_idx
% vq
->num
;
1365 used
= vq
->used
->ring
+ start
;
1366 if (__copy_to_user(used
, heads
, count
* sizeof *used
)) {
1367 vq_err(vq
, "Failed to write used");
1370 if (unlikely(vq
->log_used
)) {
1371 /* Make sure data is seen before log. */
1373 /* Log used ring entry write. */
1374 log_write(vq
->log_base
,
1376 ((void __user
*)used
- (void __user
*)vq
->used
),
1377 count
* sizeof *used
);
1379 old
= vq
->last_used_idx
;
1380 new = (vq
->last_used_idx
+= count
);
1381 /* If the driver never bothers to signal in a very long while,
1382 * used index might wrap around. If that happens, invalidate
1383 * signalled_used index we stored. TODO: make sure driver
1384 * signals at least once in 2^16 and remove this. */
1385 if (unlikely((u16
)(new - vq
->signalled_used
) < (u16
)(new - old
)))
1386 vq
->signalled_used_valid
= false;
1390 /* After we've used one of their buffers, we tell them about it. We'll then
1391 * want to notify the guest, using eventfd. */
1392 int vhost_add_used_n(struct vhost_virtqueue
*vq
, struct vring_used_elem
*heads
,
1397 start
= vq
->last_used_idx
% vq
->num
;
1398 n
= vq
->num
- start
;
1400 r
= __vhost_add_used_n(vq
, heads
, n
);
1406 r
= __vhost_add_used_n(vq
, heads
, count
);
1408 /* Make sure buffer is written before we update index. */
1410 if (put_user(vq
->last_used_idx
, &vq
->used
->idx
)) {
1411 vq_err(vq
, "Failed to increment used idx");
1414 if (unlikely(vq
->log_used
)) {
1415 /* Log used index update. */
1416 log_write(vq
->log_base
,
1417 vq
->log_addr
+ offsetof(struct vring_used
, idx
),
1418 sizeof vq
->used
->idx
);
1420 eventfd_signal(vq
->log_ctx
, 1);
1425 static bool vhost_notify(struct vhost_dev
*dev
, struct vhost_virtqueue
*vq
)
1427 __u16 old
, new, event
;
1429 /* Flush out used index updates. This is paired
1430 * with the barrier that the Guest executes when enabling
1434 if (vhost_has_feature(dev
, VIRTIO_F_NOTIFY_ON_EMPTY
) &&
1435 unlikely(vq
->avail_idx
== vq
->last_avail_idx
))
1438 if (!vhost_has_feature(dev
, VIRTIO_RING_F_EVENT_IDX
)) {
1440 if (__get_user(flags
, &vq
->avail
->flags
)) {
1441 vq_err(vq
, "Failed to get flags");
1444 return !(flags
& VRING_AVAIL_F_NO_INTERRUPT
);
1446 old
= vq
->signalled_used
;
1447 v
= vq
->signalled_used_valid
;
1448 new = vq
->signalled_used
= vq
->last_used_idx
;
1449 vq
->signalled_used_valid
= true;
1454 if (get_user(event
, vhost_used_event(vq
))) {
1455 vq_err(vq
, "Failed to get used event idx");
1458 return vring_need_event(event
, new, old
);
1461 /* This actually signals the guest, using eventfd. */
1462 void vhost_signal(struct vhost_dev
*dev
, struct vhost_virtqueue
*vq
)
1464 /* Signal the Guest tell them we used something up. */
1465 if (vq
->call_ctx
&& vhost_notify(dev
, vq
))
1466 eventfd_signal(vq
->call_ctx
, 1);
1469 /* And here's the combo meal deal. Supersize me! */
1470 void vhost_add_used_and_signal(struct vhost_dev
*dev
,
1471 struct vhost_virtqueue
*vq
,
1472 unsigned int head
, int len
)
1474 vhost_add_used(vq
, head
, len
);
1475 vhost_signal(dev
, vq
);
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
);
1487 /* OK, now we need to know about added descriptors. */
1488 bool vhost_enable_notify(struct vhost_dev
*dev
, struct vhost_virtqueue
*vq
)
1493 if (!(vq
->used_flags
& VRING_USED_F_NO_NOTIFY
))
1495 vq
->used_flags
&= ~VRING_USED_F_NO_NOTIFY
;
1496 if (!vhost_has_feature(dev
, VIRTIO_RING_F_EVENT_IDX
)) {
1497 r
= vhost_update_used_flags(vq
);
1499 vq_err(vq
, "Failed to enable notification at %p: %d\n",
1500 &vq
->used
->flags
, r
);
1504 r
= vhost_update_avail_event(vq
, vq
->avail_idx
);
1506 vq_err(vq
, "Failed to update avail event index at %p: %d\n",
1507 vhost_avail_event(vq
), r
);
1511 /* They could have slipped one in as we were doing that: make
1512 * sure it's written, then check again. */
1514 r
= __get_user(avail_idx
, &vq
->avail
->idx
);
1516 vq_err(vq
, "Failed to check avail idx at %p: %d\n",
1517 &vq
->avail
->idx
, r
);
1521 return avail_idx
!= vq
->avail_idx
;
1524 /* We don't need to be notified again. */
1525 void vhost_disable_notify(struct vhost_dev
*dev
, struct vhost_virtqueue
*vq
)
1529 if (vq
->used_flags
& VRING_USED_F_NO_NOTIFY
)
1531 vq
->used_flags
|= VRING_USED_F_NO_NOTIFY
;
1532 if (!vhost_has_feature(dev
, VIRTIO_RING_F_EVENT_IDX
)) {
1533 r
= vhost_update_used_flags(vq
);
1535 vq_err(vq
, "Failed to enable notification at %p: %d\n",
1536 &vq
->used
->flags
, r
);
1540 static void vhost_zerocopy_done_signal(struct kref
*kref
)
1542 struct vhost_ubuf_ref
*ubufs
= container_of(kref
, struct vhost_ubuf_ref
,
1544 wake_up(&ubufs
->wait
);
1547 struct vhost_ubuf_ref
*vhost_ubuf_alloc(struct vhost_virtqueue
*vq
,
1550 struct vhost_ubuf_ref
*ubufs
;
1551 /* No zero copy backend? Nothing to count. */
1554 ubufs
= kmalloc(sizeof *ubufs
, GFP_KERNEL
);
1556 return ERR_PTR(-ENOMEM
);
1557 kref_init(&ubufs
->kref
);
1558 init_waitqueue_head(&ubufs
->wait
);
1563 void vhost_ubuf_put(struct vhost_ubuf_ref
*ubufs
)
1565 kref_put(&ubufs
->kref
, vhost_zerocopy_done_signal
);
1568 void vhost_ubuf_put_and_wait(struct vhost_ubuf_ref
*ubufs
)
1570 kref_put(&ubufs
->kref
, vhost_zerocopy_done_signal
);
1571 wait_event(ubufs
->wait
, !atomic_read(&ubufs
->kref
.refcount
));