In UnsetGuardPage(), before SmmReadyToLock, remove NX and RO
memory attribute protection for guarded page since
EfiConventionalMemory in SMRAM is RW and executable before
SmmReadyToLock. If UnsetGuardPage() happens after SmmReadyToLock,
then apply EFI_MEMORY_XP to the guarded page to make sure
EfiConventionalMemory in SMRAM is NX since EfiConventionalMemory
in SMRAM is marked as NX in PiSmmCpuDxe driver when SmmReadyToLock.
Signed-off-by: Dun Tan <dun.tan@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Ray Ni <ray.ni@intel.com>
Reviewed-by: Jian J Wang <jian.j.wang@intel.com>
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>