def _get_dvr_service_port_hostid(self, context, port_id, port=None):
        port_db = port or self._core_plugin.get_port(context, port_id)
        device_owner = port_db['device_owner'] if port_db else ""
        if n_utils.is_dvr_serviced(device_owner):
            return port_db[portbindings.HOST_ID]
Returns the portbinding host_id for dvr service port.
dataset/ETHPy150Open openstack/neutron/neutron/db/l3_dvr_db.py/L3_NAT_with_dvr_db_mixin._get_dvr_service_port_hostid