On 08/12/19 12:31, Eric Dong wrote: > REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2040 > > Supports new logic which test current value before write new value. > Only write new value when current value not same as new value. > > Signed-off-by: Eric Dong <eric.d...@intel.com> > Cc: Ray Ni <ray...@intel.com> > Cc: Laszlo Ersek <ler...@redhat.com> > --- > UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c | 29 +++++++++++++++++++++++++++++ > 1 file changed, 29 insertions(+) > > diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c > b/UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c > index b20992d5ab..61541838e8 100644 > --- a/UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c > +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c > @@ -241,6 +241,7 @@ ProgramProcessorRegister ( > UINTN ValidThreadCount; > UINT32 *ValidCoreCountPerPackage; > EFI_STATUS Status; > + UINT64 CurrentValue; > > // > // Traverse Register Table of this logical processor > @@ -263,6 +264,16 @@ ProgramProcessorRegister ( > if (EFI_ERROR (Status)) { > continue; > } > + if (RegisterTableEntry->TestThenWrite) { > + CurrentValue = BitFieldRead64 ( > + Value, > + RegisterTableEntry->ValidBitStart, > + RegisterTableEntry->ValidBitStart + > RegisterTableEntry->ValidBitLength - 1 > + ); > + if (CurrentValue == RegisterTableEntry->Value) { > + continue; > + } > + } > Value = (UINTN) BitFieldWrite64 ( > Value, > RegisterTableEntry->ValidBitStart, > @@ -275,6 +286,24 @@ ProgramProcessorRegister ( > // The specified register is Model Specific Register > // > case Msr: > + if (RegisterTableEntry->TestThenWrite) { > + Value = (UINTN)AsmReadMsr64 (RegisterTableEntry->Index); > + if (RegisterTableEntry->ValidBitLength >= 64) { > + if (Value == RegisterTableEntry->Value) { > + continue; > + } > + } else { > + CurrentValue = BitFieldRead64 ( > + Value, > + RegisterTableEntry->ValidBitStart, > + RegisterTableEntry->ValidBitStart + > RegisterTableEntry->ValidBitLength - 1 > + ); > + if (CurrentValue == RegisterTableEntry->Value) { > + continue; > + } > + } > + } > + > // > // If this function is called to restore register setting after INIT > signal, > // there is no need to restore MSRs in register table. >
I assume that "RegisterTableEntry->Value" has all bits clear that fall outside of the bitmask defined by ValidBitStart and ValidBitLength. With that assumption: Reviewed-by: Laszlo Ersek <ler...@redhat.com> Thanks Laszlo -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#45441): https://edk2.groups.io/g/devel/message/45441 Mute This Topic: https://groups.io/mt/32839207/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
