vdpa: merge functionally duplicated dev_features attributes

We can merge VDPA_ATTR_VDPA_DEV_SUPPORTED_FEATURES with
VDPA_ATTR_DEV_FEATURES which is functionally equivalent.
While at it, tweak the comment in header file to make
user provioned device features distinguished from those
supported by the parent mgmtdev device: the former of
which can be inherited as a whole from the latter, or
can be a subset of the latter if explicitly specified.
Signed-off-by: Si-Wei Liu <si-wei.liu@oracle.com>
Message-Id: <1665422823-18364-1-git-send-email-si-wei.liu@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>

drivers/vdpa/vdpa.c

@@ -855,7 +855,7 @@ static int vdpa_dev_net_config_fill(struct vdpa_device *vdev, struct sk_buff *ms
 
 	features_device = vdev->config->get_device_features(vdev);
 
-	if (nla_put_u64_64bit(msg, VDPA_ATTR_VDPA_DEV_SUPPORTED_FEATURES, features_device,
+	if (nla_put_u64_64bit(msg, VDPA_ATTR_DEV_FEATURES, features_device,
 			      VDPA_ATTR_PAD))
 		return -EMSGSIZE;
 

include/uapi/linux/vdpa.h

@@ -53,11 +53,9 @@ enum vdpa_attr {
 	VDPA_ATTR_DEV_VENDOR_ATTR_NAME,		/* string */
 	VDPA_ATTR_DEV_VENDOR_ATTR_VALUE,        /* u64 */
 
+	/* virtio features that are provisioned to the vDPA device */
 	VDPA_ATTR_DEV_FEATURES,                 /* u64 */
 
-	/* virtio features that are supported by the vDPA device */
-	VDPA_ATTR_VDPA_DEV_SUPPORTED_FEATURES,	/* u64 */
-
 	/* new attributes must be added above here */
 	VDPA_ATTR_MAX,
 };