On 6/7/2023 9:51 PM, Eugenio Perez Martin wrote:
On Wed, Jun 7, 2023 at 11:09 AM Zhu Lingshan <lingshan....@intel.com> wrote:
When read the state of a virtqueue, vhost_vdpa need
to check whether the device is suspended.
This commit verifies whether VHOST_BACKEND_F_SUSPEND is
negotiated when checking vhost_vdpa->suspended.
I'll add: Otherwise, qemu prints XXX error message.
On second thought, not returning an error prevents the caller
(vhost.c:vhost_virtqueue_stop) from recovering used idx from the
guest.
I'm not sure about the right fix for this, should we call
virtio_queue_restore_last_avail_idx here? Communicate that the backend
cannot suspend so vhost.c can print a better error message?
I agree it is better not to return an error.
Instead if neither the device does not support _F_SUSPEND nor failed to
suspend,
I think vhost_vdpa should try to read the last_avail_idx from
the device anyway. We can print an error message here,
like: failed to suspend, the value may not reliable.
Thanks
Thanks!
Signed-off-by: Zhu Lingshan <lingshan....@intel.com>
---
hw/virtio/vhost-vdpa.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
index b3094e8a8b..ae176c06dd 100644
--- a/hw/virtio/vhost-vdpa.c
+++ b/hw/virtio/vhost-vdpa.c
@@ -1397,7 +1397,7 @@ static int vhost_vdpa_get_vring_base(struct vhost_dev
*dev,
return 0;
}
- if (!v->suspended) {
+ if ((dev->backend_cap & BIT_ULL(VHOST_BACKEND_F_SUSPEND)) &&
(!v->suspended)) {
/*
* Cannot trust in value returned by device, let vhost recover used
* idx from guest.
--
2.39.1
