vdpa: conditionally read STATUS in config space

The spec says:
    status only exists if VIRTIO_NET_F_STATUS is set

Similar to MAC and MTU, vdpa_dev_net_config_fill() should read
STATUS conditionally depending on the feature bits.

Signed-off-by: Si-Wei Liu <si-wei.liu@oracle.com>
Reviewed-by: Parav Pandit <parav@nvidia.com>
Reviewed-by: Eli Cohen <elic@nvidia.com>
Message-Id: <1675725124-7375-3-git-send-email-si-wei.liu@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

Author: siwliu-kernel

drivers/vdpa/vdpa.c

@@ -848,18 +848,25 @@ static int vdpa_dev_net_mac_config_fill(struct sk_buff *msg, u64 features,
 			sizeof(config->mac), config->mac);
 }
 
+static int vdpa_dev_net_status_config_fill(struct sk_buff *msg, u64 features,
+					   const struct virtio_net_config *config)
+{
+	u16 val_u16;
+
+	if ((features & BIT_ULL(VIRTIO_NET_F_STATUS)) == 0)
+		return 0;
+
+	val_u16 = __virtio16_to_cpu(true, config->status);
+	return nla_put_u16(msg, VDPA_ATTR_DEV_NET_STATUS, val_u16);
+}
+
 static int vdpa_dev_net_config_fill(struct vdpa_device *vdev, struct sk_buff *msg)
 {
 	struct virtio_net_config config = {};
 	u64 features_device;
-	u16 val_u16;
 
 	vdev->config->get_config(vdev, 0, &config, sizeof(config));
 
-	val_u16 = __virtio16_to_cpu(true, config.status);
-	if (nla_put_u16(msg, VDPA_ATTR_DEV_NET_STATUS, val_u16))
-		return -EMSGSIZE;
-
 	features_device = vdev->config->get_device_features(vdev);
 
 	if (nla_put_u64_64bit(msg, VDPA_ATTR_DEV_FEATURES, features_device,
@@ -872,6 +879,9 @@ static int vdpa_dev_net_config_fill(struct vdpa_device *vdev, struct sk_buff *ms
 	if (vdpa_dev_net_mac_config_fill(msg, features_device, &config))
 		return -EMSGSIZE;
 
+	if (vdpa_dev_net_status_config_fill(msg, features_device, &config))
+		return -EMSGSIZE;
+
 	return vdpa_dev_net_mq_config_fill(msg, features_device, &config);
 }