On 11/6/23 10:07, Sheng Wei wrote: > Do not use fixed CR4 value 0x668, change CR4.CET bit only. > > Signed-off-by: Sheng Wei <w.sh...@intel.com> > Cc: Eric Dong <eric.d...@intel.com> > Cc: Ray Ni <ray...@intel.com> > Cc: Laszlo Ersek <ler...@redhat.com> > Cc: Wu Jiaxin <jiaxin...@intel.com> > Cc: Tan Dun <dun....@intel.com> > --- > UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmiEntry.nasm | 9 ++++++--- > UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.nasm | 3 ++- > 2 files changed, 8 insertions(+), 4 deletions(-) > > diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmiEntry.nasm > b/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmiEntry.nasm > index 68332e2c3f..a087576a54 100644 > --- a/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmiEntry.nasm > +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmiEntry.nasm > @@ -260,7 +260,8 @@ CetInterruptDone: > bts ecx, 16 ; set WP > mov cr0, ecx > > - mov eax, 0x668 | CR4_CET > + mov eax, cr4 > + bts eax, CR4_CET_BIT > mov cr4, eax > > setssbsy > @@ -292,8 +293,10 @@ CetDone: > xor edx, edx > wrmsr > > - mov eax, 0x668 > - mov cr4, eax ; disable CET > + ; clear CR4.CET bit > + mov eax, cr4 > + btr eax, CR4_CET_BIT > + mov cr4, eax > > mov ecx, MSR_IA32_PL0_SSP > pop eax > diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.nasm > b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.nasm > index 007fbff640..7aed7c8dda 100644 > --- a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.nasm > +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.nasm > @@ -287,7 +287,8 @@ CetInterruptDone: > bts ecx, 16 ; set WP > mov cr0, rcx > > - mov eax, 0x668 | CR4_CET > + mov rax, cr4 > + bts rax, CR4_CET_BIT > mov cr4, rax > > setssbsy
I didn't understand why the X64 code here didn't contain the "btr" counterpart of "bts". Well the reason is that the "missing" btr is actually introduced in the previous patch. I find that confusing. I think that, once you have "Cet.inc", you should separately replace CR4_CET with CR4_CET_BIT, both in "Cet.inc" and in the three existent locations (two in the IA32 entry code and one in the X64 entry code). *Then* you could proceed to clearing CR4.CET in the subsequent patch, using CR4_CET_BIT. Laszlo -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#110927): https://edk2.groups.io/g/devel/message/110927 Mute This Topic: https://groups.io/mt/102416574/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/leave/9847357/21656/1706620634/xyzzy [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
