def METHOD_NAME(vm):
    """
    Get the maximum supported sve length of guest
    : return maximum vector length. Format: e.g sve512
    """
    try:
        session = None
        if not vm.is_alive():
            vm.start()
        session = vm.wait_for_login(timeout=120)
        ret = session.cmd(get_maxium_sve_length).strip()
        # dmesg record maximum sve length in bytes
        sve_length_byte = re.search("length (\d+) bytes", ret).groups()[0]
        # Change max_length into sve + length(bit) E.g. sve512
        sve_length_bit = "sve" + str(int(sve_length_byte) * 8)
        logging.debug("guest sve_length_bit is %s" % sve_length_bit)
    except Exception as e:
        test.fail("Failed to get guest SVE Vector length: %s" % e)
    finally:
        if session:
            session.close()
    return sve_length_bit