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vhost: set log when updating used flags or avail event 

We need to log writes when updating used flags and avail event
fields.  Otherwise the guest may see a stale value after migration and
miss notifying the host.

Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
hifive-unleashed-5.1
Jason Wang 2011-06-21 18:04:38 +08:00 committed by Michael S. Tsirkin
parent f59281dafb
commit 2723feaa8e
1 changed files with 54 additions and 30 deletions
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84
drivers/vhost/vhost.c
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@ -629,19 +629,6 @@ static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
return 0;
}
int vhost_init_used(struct vhost_virtqueue *vq)
{
int r;
if (!vq->private_data)
return 0;
r = put_user(vq->used_flags, &vq->used->flags);
if (r)
return r;
vq->signalled_used_valid = false;
return get_user(vq->last_used_idx, &vq->used->idx);
}
static long vhost_set_vring(struct vhost_dev *d, int ioctl, void __user *argp)
{
struct file *eventfp, *filep = NULL,
@ -1008,6 +995,57 @@ int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
return 0;
}
static int vhost_update_used_flags(struct vhost_virtqueue *vq)
{
void __user *used;
if (put_user(vq->used_flags, &vq->used->flags) < 0)
return -EFAULT;
if (unlikely(vq->log_used)) {
/* Make sure the flag is seen before log. */
smp_wmb();
/* Log used flag write. */
used = &vq->used->flags;
log_write(vq->log_base, vq->log_addr +
(used - (void __user *)vq->used),
sizeof vq->used->flags);
if (vq->log_ctx)
eventfd_signal(vq->log_ctx, 1);
}
return 0;
}
static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event)
{
if (put_user(vq->avail_idx, vhost_avail_event(vq)))
return -EFAULT;
if (unlikely(vq->log_used)) {
void __user *used;
/* Make sure the event is seen before log. */
smp_wmb();
/* Log avail event write */
used = vhost_avail_event(vq);
log_write(vq->log_base, vq->log_addr +
(used - (void __user *)vq->used),
sizeof *vhost_avail_event(vq));
if (vq->log_ctx)
eventfd_signal(vq->log_ctx, 1);
}
return 0;
}
int vhost_init_used(struct vhost_virtqueue *vq)
{
int r;
if (!vq->private_data)
return 0;
r = vhost_update_used_flags(vq);
if (r)
return r;
vq->signalled_used_valid = false;
return get_user(vq->last_used_idx, &vq->used->idx);
}
static int translate_desc(struct vhost_dev *dev, u64 addr, u32 len,
struct iovec iov[], int iov_size)
{
@ -1479,34 +1517,20 @@ bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
return false;
vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) {
r = put_user(vq->used_flags, &vq->used->flags);
r = vhost_update_used_flags(vq);
if (r) {
vq_err(vq, "Failed to enable notification at %p: %d\n",
&vq->used->flags, r);
return false;
}
} else {
r = put_user(vq->avail_idx, vhost_avail_event(vq));
r = vhost_update_avail_event(vq, vq->avail_idx);
if (r) {
vq_err(vq, "Failed to update avail event index at %p: %d\n",
vhost_avail_event(vq), r);
return false;
}
}
if (unlikely(vq->log_used)) {
void __user *used;
/* Make sure data is seen before log. */
smp_wmb();
used = vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX) ?
&vq->used->flags : vhost_avail_event(vq);
/* Log used flags or event index entry write. Both are 16 bit
* fields. */
log_write(vq->log_base, vq->log_addr +
(used - (void __user *)vq->used),
sizeof(u16));
if (vq->log_ctx)
eventfd_signal(vq->log_ctx, 1);
}
/* They could have slipped one in as we were doing that: make
* sure it's written, then check again. */
smp_mb();
@ -1529,7 +1553,7 @@ void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
return;
vq->used_flags |= VRING_USED_F_NO_NOTIFY;
if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) {
r = put_user(vq->used_flags, &vq->used->flags);
r = vhost_update_used_flags(vq);
if (r)
vq_err(vq, "Failed to enable notification at %p: %d\n",
&vq->used->flags, r);