On March 3, 2022 11:12 AM, Wang Jian wrote:
>
> Hi Min,
>
> I think the PCD should not be dynamic. Dynamic PCD is used for those
> features which can be changed at boot time. But, for Intel processor, it
> should always stay as FALSE. So there's no need to make it dynamic.
> FixedAtBuild should be fine.
>
I realize this PCD is not necessary. According to [TDX] Sec 10.1.5,
IA32_EFER.NXE is initialized to 1. So in the function EnableExecuteDisableBit @
MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c, we can check if BIT11 is set
before calling AsmWriteMsr64. It looks like:
VOID EnableExecuteDisableBit ( VOID )
{
UINT64 MsrRegisters;
MsrRegisters = AsmReadMsr64 (0xC0000080);
if ((MsrRegisters & BIT11) == 0) {
MsrRegisters |= BIT11;
AsmWriteMsr64 (0xC0000080, MsrRegisters);
}
}
[TDX]
https://www.intel.com/content/dam/develop/external/us/en/documents/tdx-module-1.0-public-spec-v0.931.pdf
Thanks
Min
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