[PATCH 5.10 424/452] vdpasim: allow to enable a vq repeatedly

[Greg Kroah-Hartman]

From: Eugenio Pérez <eperezma@xxxxxxxxxx>

commit 242436973831aa97e8ce19533c6c912ea8def31b upstream.

Code must be resilient to enable a queue many times.

At the moment the queue is resetting so it's definitely not the expected
behavior.

v2: set vq->ready = 0 at disable.

Fixes: 2c53d0f64c06 ("vdpasim: vDPA device simulator")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Eugenio Pérez <eperezma@xxxxxxxxxx>
Message-Id: <20220519145919.772896-1-eperezma@xxxxxxxxxx>
Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Reviewed-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/vdpa/vdpa_sim/vdpa_sim.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/drivers/vdpa/vdpa_sim/vdpa_sim.c
+++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c
@@ -473,11 +473,14 @@ static void vdpasim_set_vq_ready(struct
 {
 	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
 	struct vdpasim_virtqueue *vq = &vdpasim->vqs[idx];
+	bool old_ready;
 
 	spin_lock(&vdpasim->lock);
+	old_ready = vq->ready;
 	vq->ready = ready;
-	if (vq->ready)
+	if (vq->ready && !old_ready) {
 		vdpasim_queue_ready(vdpasim, idx);
+	}
 	spin_unlock(&vdpasim->lock);
 }