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>
29 #include <linux/net.h>
30 #include <linux/if_packet.h>
31 #include <linux/if_arp.h>
36 VHOST_MEMORY_MAX_NREGIONS
= 64,
37 VHOST_MEMORY_F_LOG
= 0x1,
40 static unsigned vhost_zcopy_mask __read_mostly
;
42 #define vhost_used_event(vq) ((u16 __user *)&vq->avail->ring[vq->num])
43 #define vhost_avail_event(vq) ((u16 __user *)&vq->used->ring[vq->num])
45 static void vhost_poll_func(struct file
*file
, wait_queue_head_t
*wqh
,
48 struct vhost_poll
*poll
;
50 poll
= container_of(pt
, struct vhost_poll
, table
);
52 add_wait_queue(wqh
, &poll
->wait
);
55 static int vhost_poll_wakeup(wait_queue_t
*wait
, unsigned mode
, int sync
,
58 struct vhost_poll
*poll
= container_of(wait
, struct vhost_poll
, wait
);
60 if (!((unsigned long)key
& poll
->mask
))
63 vhost_poll_queue(poll
);
67 static void vhost_work_init(struct vhost_work
*work
, vhost_work_fn_t fn
)
69 INIT_LIST_HEAD(&work
->node
);
71 init_waitqueue_head(&work
->done
);
73 work
->queue_seq
= work
->done_seq
= 0;
76 /* Init poll structure */
77 void vhost_poll_init(struct vhost_poll
*poll
, vhost_work_fn_t fn
,
78 unsigned long mask
, struct vhost_dev
*dev
)
80 init_waitqueue_func_entry(&poll
->wait
, vhost_poll_wakeup
);
81 init_poll_funcptr(&poll
->table
, vhost_poll_func
);
85 vhost_work_init(&poll
->work
, fn
);
88 /* Start polling a file. We add ourselves to file's wait queue. The caller must
89 * keep a reference to a file until after vhost_poll_stop is called. */
90 void vhost_poll_start(struct vhost_poll
*poll
, struct file
*file
)
94 mask
= file
->f_op
->poll(file
, &poll
->table
);
96 vhost_poll_wakeup(&poll
->wait
, 0, 0, (void *)mask
);
99 /* Stop polling a file. After this function returns, it becomes safe to drop the
100 * file reference. You must also flush afterwards. */
101 void vhost_poll_stop(struct vhost_poll
*poll
)
103 remove_wait_queue(poll
->wqh
, &poll
->wait
);
106 static bool vhost_work_seq_done(struct vhost_dev
*dev
, struct vhost_work
*work
,
111 spin_lock_irq(&dev
->work_lock
);
112 left
= seq
- work
->done_seq
;
113 spin_unlock_irq(&dev
->work_lock
);
117 static void vhost_work_flush(struct vhost_dev
*dev
, struct vhost_work
*work
)
122 spin_lock_irq(&dev
->work_lock
);
123 seq
= work
->queue_seq
;
125 spin_unlock_irq(&dev
->work_lock
);
126 wait_event(work
->done
, vhost_work_seq_done(dev
, work
, seq
));
127 spin_lock_irq(&dev
->work_lock
);
128 flushing
= --work
->flushing
;
129 spin_unlock_irq(&dev
->work_lock
);
130 BUG_ON(flushing
< 0);
133 /* Flush any work that has been scheduled. When calling this, don't hold any
134 * locks that are also used by the callback. */
135 void vhost_poll_flush(struct vhost_poll
*poll
)
137 vhost_work_flush(poll
->dev
, &poll
->work
);
140 static inline void vhost_work_queue(struct vhost_dev
*dev
,
141 struct vhost_work
*work
)
145 spin_lock_irqsave(&dev
->work_lock
, flags
);
146 if (list_empty(&work
->node
)) {
147 list_add_tail(&work
->node
, &dev
->work_list
);
149 wake_up_process(dev
->worker
);
151 spin_unlock_irqrestore(&dev
->work_lock
, flags
);
154 void vhost_poll_queue(struct vhost_poll
*poll
)
156 vhost_work_queue(poll
->dev
, &poll
->work
);
159 static void vhost_vq_reset(struct vhost_dev
*dev
,
160 struct vhost_virtqueue
*vq
)
166 vq
->last_avail_idx
= 0;
168 vq
->last_used_idx
= 0;
169 vq
->signalled_used
= 0;
170 vq
->signalled_used_valid
= false;
172 vq
->log_used
= false;
173 vq
->log_addr
= -1ull;
176 vq
->private_data
= NULL
;
178 vq
->error_ctx
= NULL
;
189 static int vhost_worker(void *data
)
191 struct vhost_dev
*dev
= data
;
192 struct vhost_work
*work
= NULL
;
193 unsigned uninitialized_var(seq
);
194 mm_segment_t oldfs
= get_fs();
200 /* mb paired w/ kthread_stop */
201 set_current_state(TASK_INTERRUPTIBLE
);
203 spin_lock_irq(&dev
->work_lock
);
205 work
->done_seq
= seq
;
207 wake_up_all(&work
->done
);
210 if (kthread_should_stop()) {
211 spin_unlock_irq(&dev
->work_lock
);
212 __set_current_state(TASK_RUNNING
);
215 if (!list_empty(&dev
->work_list
)) {
216 work
= list_first_entry(&dev
->work_list
,
217 struct vhost_work
, node
);
218 list_del_init(&work
->node
);
219 seq
= work
->queue_seq
;
222 spin_unlock_irq(&dev
->work_lock
);
225 __set_current_state(TASK_RUNNING
);
238 static void vhost_vq_free_iovecs(struct vhost_virtqueue
*vq
)
246 kfree(vq
->ubuf_info
);
247 vq
->ubuf_info
= NULL
;
250 void vhost_enable_zcopy(int vq
)
252 vhost_zcopy_mask
|= 0x1 << vq
;
255 /* Helper to allocate iovec buffers for all vqs. */
256 static long vhost_dev_alloc_iovecs(struct vhost_dev
*dev
)
261 for (i
= 0; i
< dev
->nvqs
; ++i
) {
262 dev
->vqs
[i
].indirect
= kmalloc(sizeof *dev
->vqs
[i
].indirect
*
263 UIO_MAXIOV
, GFP_KERNEL
);
264 dev
->vqs
[i
].log
= kmalloc(sizeof *dev
->vqs
[i
].log
* UIO_MAXIOV
,
266 dev
->vqs
[i
].heads
= kmalloc(sizeof *dev
->vqs
[i
].heads
*
267 UIO_MAXIOV
, GFP_KERNEL
);
268 zcopy
= vhost_zcopy_mask
& (0x1 << i
);
270 dev
->vqs
[i
].ubuf_info
=
271 kmalloc(sizeof *dev
->vqs
[i
].ubuf_info
*
272 UIO_MAXIOV
, GFP_KERNEL
);
273 if (!dev
->vqs
[i
].indirect
|| !dev
->vqs
[i
].log
||
274 !dev
->vqs
[i
].heads
||
275 (zcopy
&& !dev
->vqs
[i
].ubuf_info
))
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 long vhost_dev_init(struct vhost_dev
*dev
,
295 struct vhost_virtqueue
*vqs
, int nvqs
)
301 mutex_init(&dev
->mutex
);
303 dev
->log_file
= NULL
;
306 spin_lock_init(&dev
->work_lock
);
307 INIT_LIST_HEAD(&dev
->work_list
);
310 for (i
= 0; i
< dev
->nvqs
; ++i
) {
311 dev
->vqs
[i
].log
= NULL
;
312 dev
->vqs
[i
].indirect
= NULL
;
313 dev
->vqs
[i
].heads
= NULL
;
314 dev
->vqs
[i
].ubuf_info
= NULL
;
315 dev
->vqs
[i
].dev
= dev
;
316 mutex_init(&dev
->vqs
[i
].mutex
);
317 vhost_vq_reset(dev
, dev
->vqs
+ i
);
318 if (dev
->vqs
[i
].handle_kick
)
319 vhost_poll_init(&dev
->vqs
[i
].poll
,
320 dev
->vqs
[i
].handle_kick
, POLLIN
, dev
);
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
;
333 struct vhost_attach_cgroups_struct
{
334 struct vhost_work work
;
335 struct task_struct
*owner
;
339 static void vhost_attach_cgroups_work(struct vhost_work
*work
)
341 struct vhost_attach_cgroups_struct
*s
;
343 s
= container_of(work
, struct vhost_attach_cgroups_struct
, work
);
344 s
->ret
= cgroup_attach_task_all(s
->owner
, current
);
347 static int vhost_attach_cgroups(struct vhost_dev
*dev
)
349 struct vhost_attach_cgroups_struct attach
;
351 attach
.owner
= current
;
352 vhost_work_init(&attach
.work
, vhost_attach_cgroups_work
);
353 vhost_work_queue(dev
, &attach
.work
);
354 vhost_work_flush(dev
, &attach
.work
);
358 /* Caller should have device mutex */
359 static long vhost_dev_set_owner(struct vhost_dev
*dev
)
361 struct task_struct
*worker
;
364 /* Is there an owner already? */
370 /* No owner, become one */
371 dev
->mm
= get_task_mm(current
);
372 worker
= kthread_create(vhost_worker
, dev
, "vhost-%d", current
->pid
);
373 if (IS_ERR(worker
)) {
374 err
= PTR_ERR(worker
);
378 dev
->worker
= worker
;
379 wake_up_process(worker
); /* avoid contributing to loadavg */
381 err
= vhost_attach_cgroups(dev
);
385 err
= vhost_dev_alloc_iovecs(dev
);
391 kthread_stop(worker
);
401 /* Caller should have device mutex */
402 long vhost_dev_reset_owner(struct vhost_dev
*dev
)
404 struct vhost_memory
*memory
;
406 /* Restore memory to default empty mapping. */
407 memory
= kmalloc(offsetof(struct vhost_memory
, regions
), GFP_KERNEL
);
411 vhost_dev_cleanup(dev
, true);
413 memory
->nregions
= 0;
414 RCU_INIT_POINTER(dev
->memory
, memory
);
418 /* In case of DMA done not in order in lower device driver for some reason.
419 * upend_idx is used to track end of used idx, done_idx is used to track head
420 * of used idx. Once lower device DMA done contiguously, we will signal KVM
423 int vhost_zerocopy_signal_used(struct vhost_virtqueue
*vq
)
428 for (i
= vq
->done_idx
; i
!= vq
->upend_idx
; i
= (i
+ 1) % UIO_MAXIOV
) {
429 if ((vq
->heads
[i
].len
== VHOST_DMA_DONE_LEN
)) {
430 vq
->heads
[i
].len
= VHOST_DMA_CLEAR_LEN
;
431 vhost_add_used_and_signal(vq
->dev
, vq
,
442 /* Caller should have device mutex if and only if locked is set */
443 void vhost_dev_cleanup(struct vhost_dev
*dev
, bool locked
)
447 for (i
= 0; i
< dev
->nvqs
; ++i
) {
448 if (dev
->vqs
[i
].kick
&& dev
->vqs
[i
].handle_kick
) {
449 vhost_poll_stop(&dev
->vqs
[i
].poll
);
450 vhost_poll_flush(&dev
->vqs
[i
].poll
);
452 /* Wait for all lower device DMAs done. */
453 if (dev
->vqs
[i
].ubufs
)
454 vhost_ubuf_put_and_wait(dev
->vqs
[i
].ubufs
);
456 /* Signal guest as appropriate. */
457 vhost_zerocopy_signal_used(&dev
->vqs
[i
]);
459 if (dev
->vqs
[i
].error_ctx
)
460 eventfd_ctx_put(dev
->vqs
[i
].error_ctx
);
461 if (dev
->vqs
[i
].error
)
462 fput(dev
->vqs
[i
].error
);
463 if (dev
->vqs
[i
].kick
)
464 fput(dev
->vqs
[i
].kick
);
465 if (dev
->vqs
[i
].call_ctx
)
466 eventfd_ctx_put(dev
->vqs
[i
].call_ctx
);
467 if (dev
->vqs
[i
].call
)
468 fput(dev
->vqs
[i
].call
);
469 vhost_vq_reset(dev
, dev
->vqs
+ i
);
471 vhost_dev_free_iovecs(dev
);
473 eventfd_ctx_put(dev
->log_ctx
);
477 dev
->log_file
= NULL
;
478 /* No one will access memory at this point */
479 kfree(rcu_dereference_protected(dev
->memory
,
481 lockdep_is_held(&dev
->mutex
)));
482 RCU_INIT_POINTER(dev
->memory
, NULL
);
483 WARN_ON(!list_empty(&dev
->work_list
));
485 kthread_stop(dev
->worker
);
493 static int log_access_ok(void __user
*log_base
, u64 addr
, unsigned long sz
)
495 u64 a
= addr
/ VHOST_PAGE_SIZE
/ 8;
497 /* Make sure 64 bit math will not overflow. */
498 if (a
> ULONG_MAX
- (unsigned long)log_base
||
499 a
+ (unsigned long)log_base
> ULONG_MAX
)
502 return access_ok(VERIFY_WRITE
, log_base
+ a
,
503 (sz
+ VHOST_PAGE_SIZE
* 8 - 1) / VHOST_PAGE_SIZE
/ 8);
506 /* Caller should have vq mutex and device mutex. */
507 static int vq_memory_access_ok(void __user
*log_base
, struct vhost_memory
*mem
,
515 for (i
= 0; i
< mem
->nregions
; ++i
) {
516 struct vhost_memory_region
*m
= mem
->regions
+ i
;
517 unsigned long a
= m
->userspace_addr
;
518 if (m
->memory_size
> ULONG_MAX
)
520 else if (!access_ok(VERIFY_WRITE
, (void __user
*)a
,
523 else if (log_all
&& !log_access_ok(log_base
,
531 /* Can we switch to this memory table? */
532 /* Caller should have device mutex but not vq mutex */
533 static int memory_access_ok(struct vhost_dev
*d
, struct vhost_memory
*mem
,
538 for (i
= 0; i
< d
->nvqs
; ++i
) {
540 mutex_lock(&d
->vqs
[i
].mutex
);
541 /* If ring is inactive, will check when it's enabled. */
542 if (d
->vqs
[i
].private_data
)
543 ok
= vq_memory_access_ok(d
->vqs
[i
].log_base
, mem
,
547 mutex_unlock(&d
->vqs
[i
].mutex
);
554 static int vq_access_ok(struct vhost_dev
*d
, unsigned int num
,
555 struct vring_desc __user
*desc
,
556 struct vring_avail __user
*avail
,
557 struct vring_used __user
*used
)
559 size_t s
= vhost_has_feature(d
, VIRTIO_RING_F_EVENT_IDX
) ? 2 : 0;
560 return access_ok(VERIFY_READ
, desc
, num
* sizeof *desc
) &&
561 access_ok(VERIFY_READ
, avail
,
562 sizeof *avail
+ num
* sizeof *avail
->ring
+ s
) &&
563 access_ok(VERIFY_WRITE
, used
,
564 sizeof *used
+ num
* sizeof *used
->ring
+ s
);
567 /* Can we log writes? */
568 /* Caller should have device mutex but not vq mutex */
569 int vhost_log_access_ok(struct vhost_dev
*dev
)
571 struct vhost_memory
*mp
;
573 mp
= rcu_dereference_protected(dev
->memory
,
574 lockdep_is_held(&dev
->mutex
));
575 return memory_access_ok(dev
, mp
, 1);
578 /* Verify access for write logging. */
579 /* Caller should have vq mutex and device mutex */
580 static int vq_log_access_ok(struct vhost_dev
*d
, struct vhost_virtqueue
*vq
,
581 void __user
*log_base
)
583 struct vhost_memory
*mp
;
584 size_t s
= vhost_has_feature(d
, VIRTIO_RING_F_EVENT_IDX
) ? 2 : 0;
586 mp
= rcu_dereference_protected(vq
->dev
->memory
,
587 lockdep_is_held(&vq
->mutex
));
588 return vq_memory_access_ok(log_base
, mp
,
589 vhost_has_feature(vq
->dev
, VHOST_F_LOG_ALL
)) &&
590 (!vq
->log_used
|| log_access_ok(log_base
, vq
->log_addr
,
592 vq
->num
* sizeof *vq
->used
->ring
+ s
));
595 /* Can we start vq? */
596 /* Caller should have vq mutex and device mutex */
597 int vhost_vq_access_ok(struct vhost_virtqueue
*vq
)
599 return vq_access_ok(vq
->dev
, vq
->num
, vq
->desc
, vq
->avail
, vq
->used
) &&
600 vq_log_access_ok(vq
->dev
, vq
, vq
->log_base
);
603 static long vhost_set_memory(struct vhost_dev
*d
, struct vhost_memory __user
*m
)
605 struct vhost_memory mem
, *newmem
, *oldmem
;
606 unsigned long size
= offsetof(struct vhost_memory
, regions
);
608 if (copy_from_user(&mem
, m
, size
))
612 if (mem
.nregions
> VHOST_MEMORY_MAX_NREGIONS
)
614 newmem
= kmalloc(size
+ mem
.nregions
* sizeof *m
->regions
, GFP_KERNEL
);
618 memcpy(newmem
, &mem
, size
);
619 if (copy_from_user(newmem
->regions
, m
->regions
,
620 mem
.nregions
* sizeof *m
->regions
)) {
625 if (!memory_access_ok(d
, newmem
,
626 vhost_has_feature(d
, VHOST_F_LOG_ALL
))) {
630 oldmem
= rcu_dereference_protected(d
->memory
,
631 lockdep_is_held(&d
->mutex
));
632 rcu_assign_pointer(d
->memory
, newmem
);
638 static long vhost_set_vring(struct vhost_dev
*d
, int ioctl
, void __user
*argp
)
640 struct file
*eventfp
, *filep
= NULL
,
641 *pollstart
= NULL
, *pollstop
= NULL
;
642 struct eventfd_ctx
*ctx
= NULL
;
643 u32 __user
*idxp
= argp
;
644 struct vhost_virtqueue
*vq
;
645 struct vhost_vring_state s
;
646 struct vhost_vring_file f
;
647 struct vhost_vring_addr a
;
651 r
= get_user(idx
, idxp
);
659 mutex_lock(&vq
->mutex
);
662 case VHOST_SET_VRING_NUM
:
663 /* Resizing ring with an active backend?
664 * You don't want to do that. */
665 if (vq
->private_data
) {
669 if (copy_from_user(&s
, argp
, sizeof s
)) {
673 if (!s
.num
|| s
.num
> 0xffff || (s
.num
& (s
.num
- 1))) {
679 case VHOST_SET_VRING_BASE
:
680 /* Moving base with an active backend?
681 * You don't want to do that. */
682 if (vq
->private_data
) {
686 if (copy_from_user(&s
, argp
, sizeof s
)) {
690 if (s
.num
> 0xffff) {
694 vq
->last_avail_idx
= s
.num
;
695 /* Forget the cached index value. */
696 vq
->avail_idx
= vq
->last_avail_idx
;
698 case VHOST_GET_VRING_BASE
:
700 s
.num
= vq
->last_avail_idx
;
701 if (copy_to_user(argp
, &s
, sizeof s
))
704 case VHOST_SET_VRING_ADDR
:
705 if (copy_from_user(&a
, argp
, sizeof a
)) {
709 if (a
.flags
& ~(0x1 << VHOST_VRING_F_LOG
)) {
713 /* For 32bit, verify that the top 32bits of the user
714 data are set to zero. */
715 if ((u64
)(unsigned long)a
.desc_user_addr
!= a
.desc_user_addr
||
716 (u64
)(unsigned long)a
.used_user_addr
!= a
.used_user_addr
||
717 (u64
)(unsigned long)a
.avail_user_addr
!= a
.avail_user_addr
) {
721 if ((a
.avail_user_addr
& (sizeof *vq
->avail
->ring
- 1)) ||
722 (a
.used_user_addr
& (sizeof *vq
->used
->ring
- 1)) ||
723 (a
.log_guest_addr
& (sizeof *vq
->used
->ring
- 1))) {
728 /* We only verify access here if backend is configured.
729 * If it is not, we don't as size might not have been setup.
730 * We will verify when backend is configured. */
731 if (vq
->private_data
) {
732 if (!vq_access_ok(d
, vq
->num
,
733 (void __user
*)(unsigned long)a
.desc_user_addr
,
734 (void __user
*)(unsigned long)a
.avail_user_addr
,
735 (void __user
*)(unsigned long)a
.used_user_addr
)) {
740 /* Also validate log access for used ring if enabled. */
741 if ((a
.flags
& (0x1 << VHOST_VRING_F_LOG
)) &&
742 !log_access_ok(vq
->log_base
, a
.log_guest_addr
,
744 vq
->num
* sizeof *vq
->used
->ring
)) {
750 vq
->log_used
= !!(a
.flags
& (0x1 << VHOST_VRING_F_LOG
));
751 vq
->desc
= (void __user
*)(unsigned long)a
.desc_user_addr
;
752 vq
->avail
= (void __user
*)(unsigned long)a
.avail_user_addr
;
753 vq
->log_addr
= a
.log_guest_addr
;
754 vq
->used
= (void __user
*)(unsigned long)a
.used_user_addr
;
756 case VHOST_SET_VRING_KICK
:
757 if (copy_from_user(&f
, argp
, sizeof f
)) {
761 eventfp
= f
.fd
== -1 ? NULL
: eventfd_fget(f
.fd
);
762 if (IS_ERR(eventfp
)) {
763 r
= PTR_ERR(eventfp
);
766 if (eventfp
!= vq
->kick
) {
767 pollstop
= filep
= vq
->kick
;
768 pollstart
= vq
->kick
= eventfp
;
772 case VHOST_SET_VRING_CALL
:
773 if (copy_from_user(&f
, argp
, sizeof f
)) {
777 eventfp
= f
.fd
== -1 ? NULL
: eventfd_fget(f
.fd
);
778 if (IS_ERR(eventfp
)) {
779 r
= PTR_ERR(eventfp
);
782 if (eventfp
!= vq
->call
) {
786 vq
->call_ctx
= eventfp
?
787 eventfd_ctx_fileget(eventfp
) : NULL
;
791 case VHOST_SET_VRING_ERR
:
792 if (copy_from_user(&f
, argp
, sizeof f
)) {
796 eventfp
= f
.fd
== -1 ? NULL
: eventfd_fget(f
.fd
);
797 if (IS_ERR(eventfp
)) {
798 r
= PTR_ERR(eventfp
);
801 if (eventfp
!= vq
->error
) {
805 vq
->error_ctx
= eventfp
?
806 eventfd_ctx_fileget(eventfp
) : NULL
;
814 if (pollstop
&& vq
->handle_kick
)
815 vhost_poll_stop(&vq
->poll
);
818 eventfd_ctx_put(ctx
);
822 if (pollstart
&& vq
->handle_kick
)
823 vhost_poll_start(&vq
->poll
, vq
->kick
);
825 mutex_unlock(&vq
->mutex
);
827 if (pollstop
&& vq
->handle_kick
)
828 vhost_poll_flush(&vq
->poll
);
832 /* Caller must have device mutex */
833 long vhost_dev_ioctl(struct vhost_dev
*d
, unsigned int ioctl
, unsigned long arg
)
835 void __user
*argp
= (void __user
*)arg
;
836 struct file
*eventfp
, *filep
= NULL
;
837 struct eventfd_ctx
*ctx
= NULL
;
842 /* If you are not the owner, you can become one */
843 if (ioctl
== VHOST_SET_OWNER
) {
844 r
= vhost_dev_set_owner(d
);
848 /* You must be the owner to do anything else */
849 r
= vhost_dev_check_owner(d
);
854 case VHOST_SET_MEM_TABLE
:
855 r
= vhost_set_memory(d
, argp
);
857 case VHOST_SET_LOG_BASE
:
858 if (copy_from_user(&p
, argp
, sizeof p
)) {
862 if ((u64
)(unsigned long)p
!= p
) {
866 for (i
= 0; i
< d
->nvqs
; ++i
) {
867 struct vhost_virtqueue
*vq
;
868 void __user
*base
= (void __user
*)(unsigned long)p
;
870 mutex_lock(&vq
->mutex
);
871 /* If ring is inactive, will check when it's enabled. */
872 if (vq
->private_data
&& !vq_log_access_ok(d
, vq
, base
))
876 mutex_unlock(&vq
->mutex
);
879 case VHOST_SET_LOG_FD
:
880 r
= get_user(fd
, (int __user
*)argp
);
883 eventfp
= fd
== -1 ? NULL
: eventfd_fget(fd
);
884 if (IS_ERR(eventfp
)) {
885 r
= PTR_ERR(eventfp
);
888 if (eventfp
!= d
->log_file
) {
891 d
->log_ctx
= eventfp
?
892 eventfd_ctx_fileget(eventfp
) : NULL
;
895 for (i
= 0; i
< d
->nvqs
; ++i
) {
896 mutex_lock(&d
->vqs
[i
].mutex
);
897 d
->vqs
[i
].log_ctx
= d
->log_ctx
;
898 mutex_unlock(&d
->vqs
[i
].mutex
);
901 eventfd_ctx_put(ctx
);
906 r
= vhost_set_vring(d
, ioctl
, argp
);
913 static const struct vhost_memory_region
*find_region(struct vhost_memory
*mem
,
914 __u64 addr
, __u32 len
)
916 struct vhost_memory_region
*reg
;
919 /* linear search is not brilliant, but we really have on the order of 6
920 * regions in practice */
921 for (i
= 0; i
< mem
->nregions
; ++i
) {
922 reg
= mem
->regions
+ i
;
923 if (reg
->guest_phys_addr
<= addr
&&
924 reg
->guest_phys_addr
+ reg
->memory_size
- 1 >= addr
)
930 /* TODO: This is really inefficient. We need something like get_user()
931 * (instruction directly accesses the data, with an exception table entry
932 * returning -EFAULT). See Documentation/x86/exception-tables.txt.
934 static int set_bit_to_user(int nr
, void __user
*addr
)
936 unsigned long log
= (unsigned long)addr
;
939 int bit
= nr
+ (log
% PAGE_SIZE
) * 8;
942 r
= get_user_pages_fast(log
, 1, 1, &page
);
946 base
= kmap_atomic(page
);
949 set_page_dirty_lock(page
);
954 static int log_write(void __user
*log_base
,
955 u64 write_address
, u64 write_length
)
957 u64 write_page
= write_address
/ VHOST_PAGE_SIZE
;
962 write_length
+= write_address
% VHOST_PAGE_SIZE
;
964 u64 base
= (u64
)(unsigned long)log_base
;
965 u64 log
= base
+ write_page
/ 8;
966 int bit
= write_page
% 8;
967 if ((u64
)(unsigned long)log
!= log
)
969 r
= set_bit_to_user(bit
, (void __user
*)(unsigned long)log
);
972 if (write_length
<= VHOST_PAGE_SIZE
)
974 write_length
-= VHOST_PAGE_SIZE
;
980 int vhost_log_write(struct vhost_virtqueue
*vq
, struct vhost_log
*log
,
981 unsigned int log_num
, u64 len
)
985 /* Make sure data written is seen before log. */
987 for (i
= 0; i
< log_num
; ++i
) {
988 u64 l
= min(log
[i
].len
, len
);
989 r
= log_write(vq
->log_base
, log
[i
].addr
, l
);
995 eventfd_signal(vq
->log_ctx
, 1);
999 /* Length written exceeds what we have stored. This is a bug. */
1004 static int vhost_update_used_flags(struct vhost_virtqueue
*vq
)
1007 if (__put_user(vq
->used_flags
, &vq
->used
->flags
) < 0)
1009 if (unlikely(vq
->log_used
)) {
1010 /* Make sure the flag is seen before log. */
1012 /* Log used flag write. */
1013 used
= &vq
->used
->flags
;
1014 log_write(vq
->log_base
, vq
->log_addr
+
1015 (used
- (void __user
*)vq
->used
),
1016 sizeof vq
->used
->flags
);
1018 eventfd_signal(vq
->log_ctx
, 1);
1023 static int vhost_update_avail_event(struct vhost_virtqueue
*vq
, u16 avail_event
)
1025 if (__put_user(vq
->avail_idx
, vhost_avail_event(vq
)))
1027 if (unlikely(vq
->log_used
)) {
1029 /* Make sure the event is seen before log. */
1031 /* Log avail event write */
1032 used
= vhost_avail_event(vq
);
1033 log_write(vq
->log_base
, vq
->log_addr
+
1034 (used
- (void __user
*)vq
->used
),
1035 sizeof *vhost_avail_event(vq
));
1037 eventfd_signal(vq
->log_ctx
, 1);
1042 int vhost_init_used(struct vhost_virtqueue
*vq
)
1045 if (!vq
->private_data
)
1048 r
= vhost_update_used_flags(vq
);
1051 vq
->signalled_used_valid
= false;
1052 return get_user(vq
->last_used_idx
, &vq
->used
->idx
);
1055 static int translate_desc(struct vhost_dev
*dev
, u64 addr
, u32 len
,
1056 struct iovec iov
[], int iov_size
)
1058 const struct vhost_memory_region
*reg
;
1059 struct vhost_memory
*mem
;
1066 mem
= rcu_dereference(dev
->memory
);
1067 while ((u64
)len
> s
) {
1069 if (unlikely(ret
>= iov_size
)) {
1073 reg
= find_region(mem
, addr
, len
);
1074 if (unlikely(!reg
)) {
1079 size
= reg
->memory_size
- addr
+ reg
->guest_phys_addr
;
1080 _iov
->iov_len
= min((u64
)len
, size
);
1081 _iov
->iov_base
= (void __user
*)(unsigned long)
1082 (reg
->userspace_addr
+ addr
- reg
->guest_phys_addr
);
1092 /* Each buffer in the virtqueues is actually a chain of descriptors. This
1093 * function returns the next descriptor in the chain,
1094 * or -1U if we're at the end. */
1095 static unsigned next_desc(struct vring_desc
*desc
)
1099 /* If this descriptor says it doesn't chain, we're done. */
1100 if (!(desc
->flags
& VRING_DESC_F_NEXT
))
1103 /* Check they're not leading us off end of descriptors. */
1105 /* Make sure compiler knows to grab that: we don't want it changing! */
1106 /* We will use the result as an index in an array, so most
1107 * architectures only need a compiler barrier here. */
1108 read_barrier_depends();
1113 static int get_indirect(struct vhost_dev
*dev
, struct vhost_virtqueue
*vq
,
1114 struct iovec iov
[], unsigned int iov_size
,
1115 unsigned int *out_num
, unsigned int *in_num
,
1116 struct vhost_log
*log
, unsigned int *log_num
,
1117 struct vring_desc
*indirect
)
1119 struct vring_desc desc
;
1120 unsigned int i
= 0, count
, found
= 0;
1124 if (unlikely(indirect
->len
% sizeof desc
)) {
1125 vq_err(vq
, "Invalid length in indirect descriptor: "
1126 "len 0x%llx not multiple of 0x%zx\n",
1127 (unsigned long long)indirect
->len
,
1132 ret
= translate_desc(dev
, indirect
->addr
, indirect
->len
, vq
->indirect
,
1134 if (unlikely(ret
< 0)) {
1135 vq_err(vq
, "Translation failure %d in indirect.\n", ret
);
1139 /* We will use the result as an address to read from, so most
1140 * architectures only need a compiler barrier here. */
1141 read_barrier_depends();
1143 count
= indirect
->len
/ sizeof desc
;
1144 /* Buffers are chained via a 16 bit next field, so
1145 * we can have at most 2^16 of these. */
1146 if (unlikely(count
> USHRT_MAX
+ 1)) {
1147 vq_err(vq
, "Indirect buffer length too big: %d\n",
1153 unsigned iov_count
= *in_num
+ *out_num
;
1154 if (unlikely(++found
> count
)) {
1155 vq_err(vq
, "Loop detected: last one at %u "
1156 "indirect size %u\n",
1160 if (unlikely(memcpy_fromiovec((unsigned char *)&desc
,
1161 vq
->indirect
, sizeof desc
))) {
1162 vq_err(vq
, "Failed indirect descriptor: idx %d, %zx\n",
1163 i
, (size_t)indirect
->addr
+ i
* sizeof desc
);
1166 if (unlikely(desc
.flags
& VRING_DESC_F_INDIRECT
)) {
1167 vq_err(vq
, "Nested indirect descriptor: idx %d, %zx\n",
1168 i
, (size_t)indirect
->addr
+ i
* sizeof desc
);
1172 ret
= translate_desc(dev
, desc
.addr
, desc
.len
, iov
+ iov_count
,
1173 iov_size
- iov_count
);
1174 if (unlikely(ret
< 0)) {
1175 vq_err(vq
, "Translation failure %d indirect idx %d\n",
1179 /* If this is an input descriptor, increment that count. */
1180 if (desc
.flags
& VRING_DESC_F_WRITE
) {
1182 if (unlikely(log
)) {
1183 log
[*log_num
].addr
= desc
.addr
;
1184 log
[*log_num
].len
= desc
.len
;
1188 /* If it's an output descriptor, they're all supposed
1189 * to come before any input descriptors. */
1190 if (unlikely(*in_num
)) {
1191 vq_err(vq
, "Indirect descriptor "
1192 "has out after in: idx %d\n", i
);
1197 } while ((i
= next_desc(&desc
)) != -1);
1201 /* This looks in the virtqueue and for the first available buffer, and converts
1202 * it to an iovec for convenient access. Since descriptors consist of some
1203 * number of output then some number of input descriptors, it's actually two
1204 * iovecs, but we pack them into one and note how many of each there were.
1206 * This function returns the descriptor number found, or vq->num (which is
1207 * never a valid descriptor number) if none was found. A negative code is
1208 * returned on error. */
1209 int vhost_get_vq_desc(struct vhost_dev
*dev
, struct vhost_virtqueue
*vq
,
1210 struct iovec iov
[], unsigned int iov_size
,
1211 unsigned int *out_num
, unsigned int *in_num
,
1212 struct vhost_log
*log
, unsigned int *log_num
)
1214 struct vring_desc desc
;
1215 unsigned int i
, head
, found
= 0;
1219 /* Check it isn't doing very strange things with descriptor numbers. */
1220 last_avail_idx
= vq
->last_avail_idx
;
1221 if (unlikely(__get_user(vq
->avail_idx
, &vq
->avail
->idx
))) {
1222 vq_err(vq
, "Failed to access avail idx at %p\n",
1227 if (unlikely((u16
)(vq
->avail_idx
- last_avail_idx
) > vq
->num
)) {
1228 vq_err(vq
, "Guest moved used index from %u to %u",
1229 last_avail_idx
, vq
->avail_idx
);
1233 /* If there's nothing new since last we looked, return invalid. */
1234 if (vq
->avail_idx
== last_avail_idx
)
1237 /* Only get avail ring entries after they have been exposed by guest. */
1240 /* Grab the next descriptor number they're advertising, and increment
1241 * the index we've seen. */
1242 if (unlikely(__get_user(head
,
1243 &vq
->avail
->ring
[last_avail_idx
% vq
->num
]))) {
1244 vq_err(vq
, "Failed to read head: idx %d address %p\n",
1246 &vq
->avail
->ring
[last_avail_idx
% vq
->num
]);
1250 /* If their number is silly, that's an error. */
1251 if (unlikely(head
>= vq
->num
)) {
1252 vq_err(vq
, "Guest says index %u > %u is available",
1257 /* When we start there are none of either input nor output. */
1258 *out_num
= *in_num
= 0;
1264 unsigned iov_count
= *in_num
+ *out_num
;
1265 if (unlikely(i
>= vq
->num
)) {
1266 vq_err(vq
, "Desc index is %u > %u, head = %u",
1270 if (unlikely(++found
> vq
->num
)) {
1271 vq_err(vq
, "Loop detected: last one at %u "
1272 "vq size %u head %u\n",
1276 ret
= __copy_from_user(&desc
, vq
->desc
+ i
, sizeof desc
);
1277 if (unlikely(ret
)) {
1278 vq_err(vq
, "Failed to get descriptor: idx %d addr %p\n",
1282 if (desc
.flags
& VRING_DESC_F_INDIRECT
) {
1283 ret
= get_indirect(dev
, vq
, iov
, iov_size
,
1285 log
, log_num
, &desc
);
1286 if (unlikely(ret
< 0)) {
1287 vq_err(vq
, "Failure detected "
1288 "in indirect descriptor at idx %d\n", i
);
1294 ret
= translate_desc(dev
, desc
.addr
, desc
.len
, iov
+ iov_count
,
1295 iov_size
- iov_count
);
1296 if (unlikely(ret
< 0)) {
1297 vq_err(vq
, "Translation failure %d descriptor idx %d\n",
1301 if (desc
.flags
& VRING_DESC_F_WRITE
) {
1302 /* If this is an input descriptor,
1303 * increment that count. */
1305 if (unlikely(log
)) {
1306 log
[*log_num
].addr
= desc
.addr
;
1307 log
[*log_num
].len
= desc
.len
;
1311 /* If it's an output descriptor, they're all supposed
1312 * to come before any input descriptors. */
1313 if (unlikely(*in_num
)) {
1314 vq_err(vq
, "Descriptor has out after in: "
1320 } while ((i
= next_desc(&desc
)) != -1);
1322 /* On success, increment avail index. */
1323 vq
->last_avail_idx
++;
1325 /* Assume notifications from guest are disabled at this point,
1326 * if they aren't we would need to update avail_event index. */
1327 BUG_ON(!(vq
->used_flags
& VRING_USED_F_NO_NOTIFY
));
1331 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
1332 void vhost_discard_vq_desc(struct vhost_virtqueue
*vq
, int n
)
1334 vq
->last_avail_idx
-= n
;
1337 /* After we've used one of their buffers, we tell them about it. We'll then
1338 * want to notify the guest, using eventfd. */
1339 int vhost_add_used(struct vhost_virtqueue
*vq
, unsigned int head
, int len
)
1341 struct vring_used_elem __user
*used
;
1343 /* The virtqueue contains a ring of used buffers. Get a pointer to the
1344 * next entry in that used ring. */
1345 used
= &vq
->used
->ring
[vq
->last_used_idx
% vq
->num
];
1346 if (__put_user(head
, &used
->id
)) {
1347 vq_err(vq
, "Failed to write used id");
1350 if (__put_user(len
, &used
->len
)) {
1351 vq_err(vq
, "Failed to write used len");
1354 /* Make sure buffer is written before we update index. */
1356 if (__put_user(vq
->last_used_idx
+ 1, &vq
->used
->idx
)) {
1357 vq_err(vq
, "Failed to increment used idx");
1360 if (unlikely(vq
->log_used
)) {
1361 /* Make sure data is seen before log. */
1363 /* Log used ring entry write. */
1364 log_write(vq
->log_base
,
1366 ((void __user
*)used
- (void __user
*)vq
->used
),
1368 /* Log used index update. */
1369 log_write(vq
->log_base
,
1370 vq
->log_addr
+ offsetof(struct vring_used
, idx
),
1371 sizeof vq
->used
->idx
);
1373 eventfd_signal(vq
->log_ctx
, 1);
1375 vq
->last_used_idx
++;
1376 /* If the driver never bothers to signal in a very long while,
1377 * used index might wrap around. If that happens, invalidate
1378 * signalled_used index we stored. TODO: make sure driver
1379 * signals at least once in 2^16 and remove this. */
1380 if (unlikely(vq
->last_used_idx
== vq
->signalled_used
))
1381 vq
->signalled_used_valid
= false;
1385 static int __vhost_add_used_n(struct vhost_virtqueue
*vq
,
1386 struct vring_used_elem
*heads
,
1389 struct vring_used_elem __user
*used
;
1393 start
= vq
->last_used_idx
% vq
->num
;
1394 used
= vq
->used
->ring
+ start
;
1395 if (__copy_to_user(used
, heads
, count
* sizeof *used
)) {
1396 vq_err(vq
, "Failed to write used");
1399 if (unlikely(vq
->log_used
)) {
1400 /* Make sure data is seen before log. */
1402 /* Log used ring entry write. */
1403 log_write(vq
->log_base
,
1405 ((void __user
*)used
- (void __user
*)vq
->used
),
1406 count
* sizeof *used
);
1408 old
= vq
->last_used_idx
;
1409 new = (vq
->last_used_idx
+= count
);
1410 /* If the driver never bothers to signal in a very long while,
1411 * used index might wrap around. If that happens, invalidate
1412 * signalled_used index we stored. TODO: make sure driver
1413 * signals at least once in 2^16 and remove this. */
1414 if (unlikely((u16
)(new - vq
->signalled_used
) < (u16
)(new - old
)))
1415 vq
->signalled_used_valid
= false;
1419 /* After we've used one of their buffers, we tell them about it. We'll then
1420 * want to notify the guest, using eventfd. */
1421 int vhost_add_used_n(struct vhost_virtqueue
*vq
, struct vring_used_elem
*heads
,
1426 start
= vq
->last_used_idx
% vq
->num
;
1427 n
= vq
->num
- start
;
1429 r
= __vhost_add_used_n(vq
, heads
, n
);
1435 r
= __vhost_add_used_n(vq
, heads
, count
);
1437 /* Make sure buffer is written before we update index. */
1439 if (put_user(vq
->last_used_idx
, &vq
->used
->idx
)) {
1440 vq_err(vq
, "Failed to increment used idx");
1443 if (unlikely(vq
->log_used
)) {
1444 /* Log used index update. */
1445 log_write(vq
->log_base
,
1446 vq
->log_addr
+ offsetof(struct vring_used
, idx
),
1447 sizeof vq
->used
->idx
);
1449 eventfd_signal(vq
->log_ctx
, 1);
1454 static bool vhost_notify(struct vhost_dev
*dev
, struct vhost_virtqueue
*vq
)
1456 __u16 old
, new, event
;
1458 /* Flush out used index updates. This is paired
1459 * with the barrier that the Guest executes when enabling
1463 if (vhost_has_feature(dev
, VIRTIO_F_NOTIFY_ON_EMPTY
) &&
1464 unlikely(vq
->avail_idx
== vq
->last_avail_idx
))
1467 if (!vhost_has_feature(dev
, VIRTIO_RING_F_EVENT_IDX
)) {
1469 if (__get_user(flags
, &vq
->avail
->flags
)) {
1470 vq_err(vq
, "Failed to get flags");
1473 return !(flags
& VRING_AVAIL_F_NO_INTERRUPT
);
1475 old
= vq
->signalled_used
;
1476 v
= vq
->signalled_used_valid
;
1477 new = vq
->signalled_used
= vq
->last_used_idx
;
1478 vq
->signalled_used_valid
= true;
1483 if (get_user(event
, vhost_used_event(vq
))) {
1484 vq_err(vq
, "Failed to get used event idx");
1487 return vring_need_event(event
, new, old
);
1490 /* This actually signals the guest, using eventfd. */
1491 void vhost_signal(struct vhost_dev
*dev
, struct vhost_virtqueue
*vq
)
1493 /* Signal the Guest tell them we used something up. */
1494 if (vq
->call_ctx
&& vhost_notify(dev
, vq
))
1495 eventfd_signal(vq
->call_ctx
, 1);
1498 /* And here's the combo meal deal. Supersize me! */
1499 void vhost_add_used_and_signal(struct vhost_dev
*dev
,
1500 struct vhost_virtqueue
*vq
,
1501 unsigned int head
, int len
)
1503 vhost_add_used(vq
, head
, len
);
1504 vhost_signal(dev
, vq
);
1507 /* multi-buffer version of vhost_add_used_and_signal */
1508 void vhost_add_used_and_signal_n(struct vhost_dev
*dev
,
1509 struct vhost_virtqueue
*vq
,
1510 struct vring_used_elem
*heads
, unsigned count
)
1512 vhost_add_used_n(vq
, heads
, count
);
1513 vhost_signal(dev
, vq
);
1516 /* OK, now we need to know about added descriptors. */
1517 bool vhost_enable_notify(struct vhost_dev
*dev
, struct vhost_virtqueue
*vq
)
1522 if (!(vq
->used_flags
& VRING_USED_F_NO_NOTIFY
))
1524 vq
->used_flags
&= ~VRING_USED_F_NO_NOTIFY
;
1525 if (!vhost_has_feature(dev
, VIRTIO_RING_F_EVENT_IDX
)) {
1526 r
= vhost_update_used_flags(vq
);
1528 vq_err(vq
, "Failed to enable notification at %p: %d\n",
1529 &vq
->used
->flags
, r
);
1533 r
= vhost_update_avail_event(vq
, vq
->avail_idx
);
1535 vq_err(vq
, "Failed to update avail event index at %p: %d\n",
1536 vhost_avail_event(vq
), r
);
1540 /* They could have slipped one in as we were doing that: make
1541 * sure it's written, then check again. */
1543 r
= __get_user(avail_idx
, &vq
->avail
->idx
);
1545 vq_err(vq
, "Failed to check avail idx at %p: %d\n",
1546 &vq
->avail
->idx
, r
);
1550 return avail_idx
!= vq
->avail_idx
;
1553 /* We don't need to be notified again. */
1554 void vhost_disable_notify(struct vhost_dev
*dev
, struct vhost_virtqueue
*vq
)
1558 if (vq
->used_flags
& VRING_USED_F_NO_NOTIFY
)
1560 vq
->used_flags
|= VRING_USED_F_NO_NOTIFY
;
1561 if (!vhost_has_feature(dev
, VIRTIO_RING_F_EVENT_IDX
)) {
1562 r
= vhost_update_used_flags(vq
);
1564 vq_err(vq
, "Failed to enable notification at %p: %d\n",
1565 &vq
->used
->flags
, r
);
1569 static void vhost_zerocopy_done_signal(struct kref
*kref
)
1571 struct vhost_ubuf_ref
*ubufs
= container_of(kref
, struct vhost_ubuf_ref
,
1573 wake_up(&ubufs
->wait
);
1576 struct vhost_ubuf_ref
*vhost_ubuf_alloc(struct vhost_virtqueue
*vq
,
1579 struct vhost_ubuf_ref
*ubufs
;
1580 /* No zero copy backend? Nothing to count. */
1583 ubufs
= kmalloc(sizeof *ubufs
, GFP_KERNEL
);
1585 return ERR_PTR(-ENOMEM
);
1586 kref_init(&ubufs
->kref
);
1587 init_waitqueue_head(&ubufs
->wait
);
1592 void vhost_ubuf_put(struct vhost_ubuf_ref
*ubufs
)
1594 kref_put(&ubufs
->kref
, vhost_zerocopy_done_signal
);
1597 void vhost_ubuf_put_and_wait(struct vhost_ubuf_ref
*ubufs
)
1599 kref_put(&ubufs
->kref
, vhost_zerocopy_done_signal
);
1600 wait_event(ubufs
->wait
, !atomic_read(&ubufs
->kref
.refcount
));
1604 void vhost_zerocopy_callback(struct ubuf_info
*ubuf
)
1606 struct vhost_ubuf_ref
*ubufs
= ubuf
->ctx
;
1607 struct vhost_virtqueue
*vq
= ubufs
->vq
;
1609 vhost_poll_queue(&vq
->poll
);
1610 /* set len = 1 to mark this desc buffers done DMA */
1611 vq
->heads
[ubuf
->desc
].len
= VHOST_DMA_DONE_LEN
;
1612 kref_put(&ubufs
->kref
, vhost_zerocopy_done_signal
);