Non-leaf entry doesn't have PAT bit. So "& (~IA32_PE_BASE_ADDRESS_MASK_40)" is to make sure PAT bit in the original big-leaf entry is not assigned to the corresponding bit (bit 12) in non-leaf entry.
Can you please add comments to explain why? With that, Reviewed-by: Ray Ni <ray...@intel.com> > -----Original Message----- > From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Ni, Ray > Sent: Thursday, March 23, 2023 8:35 PM > To: Tan, Dun <dun....@intel.com>; devel@edk2.groups.io > Cc: Dong, Eric <eric.d...@intel.com>; Kumar, Rahul R > <rahul.r.ku...@intel.com>; Gerd Hoffmann <kra...@redhat.com> > Subject: Re: [edk2-devel] [Patch V4 06/21] UefiCpuPkg/CpuPageTableLib: Fix > issue when splitting leaf entry > > > + ParentPagingEntry->Uint64 = ((UINTN)(VOID *)PagingEntry) | > > (ParentPagingEntry->Uint64 & (~IA32_PE_BASE_ADDRESS_MASK_40)); > > In this branch, ParentPagingEntry is a leaf entry covering 2M or 1G physical > address range. > Then, why not use IA32_PE_BASE_ADDRESS_MASK_39? Because for the two > types leaf entry, address > only occupies 39 bits, not 40bits. > > > > > -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#101717): https://edk2.groups.io/g/devel/message/101717 Mute This Topic: https://groups.io/mt/97796379/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/leave/9847357/21656/1706620634/xyzzy [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
