Subject: vhost: used ring logging cleanup
remove extra log bit setting for used ring updates: it's no longer
necessary. Also, use vhost_avail_event instead of duplicating offset
math.
Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
---
> We need set log when updating used flags and avail event. Otherwise guest may
> see stale values after migration and then do not exit or exit unexpectedly.
>
> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
OK but this means we set the log twice now.
Also, hardcording offset is not as nice as using
vhost_avail_event. So I think the below is needed
on top. Comments?
drivers/vhost/vhost.c | 29 +++++++++--------------------
1 files changed, 9 insertions(+), 20 deletions(-)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 540591b..c5f96ba 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -946,14 +946,16 @@ int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
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. */
- log_write(vq->log_base,
- vq->log_addr + offsetof(struct vring_used, flags),
+ 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);
@@ -966,13 +968,14 @@ 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 */
- log_write(vq->log_base,
- vq->log_addr + offsetof(struct vring_used,
- ring[vq->num]),
- sizeof avail_event);
+ 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);
}
@@ -1474,20 +1477,6 @@ bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
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();
--
1.7.5.53.gc233e
--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
