According to VTd spec, the real hardware decoded limit should be PHMR/PLMR.Limit value + alignment value. "Bits N:0 of the limit register are decoded by hardware as all 1s." Cc: Jiewen Yao <jiewen.yao@intel.com> Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Star Zeng <star.zeng@intel.com> Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>