5-level paging is introduced by "https://software.intel.com/en-us/download/5-level-paging-and-5-level-ept-white-paper". This bugzilla records the effort to change SMM CPU driver to support 5-level paging.
[edk2-devel] [PATCH 0/3] Enable 5 level paging when CPU supports http://mid.mail-archive.com/20190628064700.549472-1-ray.ni@intel.com https://edk2.groups.io/g/devel/message/42976
This is a feature change.
pushed @ 4e78c7bebb2..c630f69df01