Re: [edk2-devel] [PATCH v1 03/13] UefiCpuPkg/SmmRelocationLib: Add library instance for OVMF

["Wu, Jiaxin" <jiaxin.wu@intel.com>]

> 
> On Mon, Apr 15, 2024 at 01:04:58PM +0000, Wu, Jiaxin wrote:
> > Hi Gred,
> >
> > Because:
> > 1) The mode of the CPU check is different between the AMD & OVMF.
> > OVMF:
> > CpuSaveState->x86.SMMRevId & 0Xffff
> >
> > AMD:
> >  LMAValue = (UINT32)AsmReadMsr64 (EFER_ADDRESS) & LMA
> >
> > 2) Existing SmBase configuration is different between the AMD & OVMF.
> > OVMF:
> >  AmdCpuState->x64.SMBASE = (UINT32)mSmBaseForAllCpus[CpuIndex];
> >
> > AMD:
> >  if ((CpuSaveState->x86.SMMRevId & 0xFFFF) == 0) {
> >     CpuSaveState->x86.SMBASE = (UINT32)mSmBaseForAllCpus[CpuIndex];
> >   } else {
> >     CpuSaveState->x64.SMBASE = (UINT32)mSmBaseForAllCpus[CpuIndex];
> >   }
> >
> > This series patch won't change the existing implementation code logic, so, we
> need override one version for OVMF.
> 
> The real question is why do these differences exist and are they
> actually needed.
> 
> I'd expect the CPU mode check return identical results.

I don't the background why AMD and OVMF has such difference. Maybe OVFM doesn't not support the MSR "EFER_ADDRESS".

> 
> The SmBase configuration for OVMF looks suspicious to me.  I'm wondering
> whenever the OVMF code actually works in Ia32 builds ...
> 

Yes, I will fix it in the next version. Currently, please build it with SMM_REQUIRE == TRUE. In the next version, I will make sure all pass the check.

> take care,
>   Gerd



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