[edk2-devel] [PATCH 07/23] MdePkg: Update BaseIoLibIntrinsicSev to support Tdx

[Gerd Hoffmann]

  Hi,

> > One more question:  How does this align with the WorkArea changes posted
> > yesterday?  The WorkArea gets a mode field for SEV / TDX / normal, so I think
> > you should be able to use that instead of invoking cpuid each time you need
> > to know whenever tdx is active or not.
> We don't want to make the TdxProbeLib depend on the WorkArea.

Why?

> CPUID(0x21) makes TdxProbeLib less dependency.  For Intel TDX the
> WorkArea is designed to be used in ResetVector phase.

I don't see why the dependency is a problem.  TDX-enabled builds need
both TdxProbeLib / TdxLib and WorkArea anyway.

Each cpuid instruction is a vmexit, and the code invokes cpuid twice for
each io / mmio access.

take care,
  Gerd



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