vhost_vdpa: tell vqs about the negotiated

As is done in the net, iscsi, and vsock vhost support, let the vdpa vqs
know about the features that have been negotiated.  This allows vhost
to more safely make decisions based on the features, such as when using
PACKED vs split queues.
Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20230424225031.18947-2-shannon.nelson@amd.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/vhost/vdpa.c

@@ -407,7 +407,10 @@ static long vhost_vdpa_set_features(struct vhost_vdpa *v, u64 __user *featurep)
 {
 	struct vdpa_device *vdpa = v->vdpa;
 	const struct vdpa_config_ops *ops = vdpa->config;
+	struct vhost_dev *d = &v->vdev;
+	u64 actual_features;
 	u64 features;
+	int i;
 
 	/*
 	 * It's not allowed to change the features after they have
@@ -422,6 +425,16 @@ static long vhost_vdpa_set_features(struct vhost_vdpa *v, u64 __user *featurep)
 	if (vdpa_set_features(vdpa, features))
 		return -EINVAL;
 
+	/* let the vqs know what has been configured */
+	actual_features = ops->get_driver_features(vdpa);
+	for (i = 0; i < d->nvqs; ++i) {
+		struct vhost_virtqueue *vq = d->vqs[i];
+
+		mutex_lock(&vq->mutex);
+		vq->acked_features = actual_features;
+		mutex_unlock(&vq->mutex);
+	}
+
 	return 0;
 }