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authorJason Wang <jasowang@redhat.com>2011-06-21 18:04:38 +0800
committerMichael S. Tsirkin <mst@redhat.com>2011-07-19 13:28:34 +0300
commit2723feaa8ec64f677f644c9189ed87d83f5559c1 (patch)
tree23ecb435e42dac4614c5470935e813cf91f74c5d /drivers/vhost
parentf59281dafb832b161133743fcf3dc29051e6fdb8 (diff)
downloadlinux-linaro-stable-2723feaa8ec64f677f644c9189ed87d83f5559c1.tar.gz
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>
Diffstat (limited to 'drivers/vhost')
-rw-r--r--drivers/vhost/vhost.c84
1 files changed, 54 insertions, 30 deletions
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 9a108038fe52..46822c0d9f7f 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -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);