Reuse most of the existing code to implement a variable runtime driver that will be able to execute in the context of standalone MM. Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Jian J Wang <jian.j.wang@intel.com> Reviewed-by: Star Zeng <star.zeng@intel.com>