Re: [PATCH v5 1/2] UefiCpuPkg/SmmCpuFeaturesLib: Use global variables to replace macros

[Paolo Bonzini <pbonzini@redhat.com>]

On 14/10/2017 17:51, Duran, Leo wrote:
>>> +  // Override PSD offset for AMD
>>> +  //
>>> +  if (SmmStandardSignatureIsAuthenticAMD ()) {
>>> +    gStmPsdOffset = AMD_SMM_PSD_OFFSET;  }
>>> +
>> I think the right thing to do here would be to use the SMM state save map
>> revision; in the case of AMD, the low 16 bits (IIRC) would be 0x0064.
>>
> Hi Paolo,
> 
> In its current form, the patch merely replaces the macros with global
> variables, and does not attempt to disrupt the existing execution
> flow. But perhaps you can provide a bit more context (or an example)
> so that may better understand your suggestion?
The offsets don't really depend on Intel vs. AMD, but rather on the
version of the state save map.  QEMU and KVM for example always use the
AMD format because it's documented better (Intel doesn't document the
descriptor cache fields in the SDM), even if the CPUID vendor is
GenuineIntel.

I am not sure if you have the SMM state save map revision at this point
of the code, and likewise for 2/2.  But if you do, it would be much
nicer for us virtualization folks if you used it instead of CPUID to
pick the offsets.

Paolo