Re: [PATCH 01/26] x86/tdx: Detect running as a TDX guest in early boot

[Kirill A. Shutemov]

On Tue, Dec 14, 2021 at 07:18:14PM +0100, Borislav Petkov wrote:
> > In preparation of extending cc_platform_has() API to support TDX guest,
> > use CPUID instruction to detect for TDX guests support in the early
> 
> " ... to detect support for TDX guests... "

Right, thanks.

> > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> > index 793e9b42ace0..a61ac6f8821a 100644
> > --- a/arch/x86/Kconfig
> > +++ b/arch/x86/Kconfig
> > @@ -872,6 +872,19 @@ config ACRN_GUEST
> >  	  IOT with small footprint and real-time features. More details can be
> >  	  found in https://projectacrn.org/.
> >  
> > +# TDX guest uses X2APIC for interrupt management.
> 
> For whom is that comment and who's going to see it? Is that comment
> supposed to explain the "depends on X86_X2APIC" below?

Yes.

But I think it should be pretty self-explanatory. I'll drop it.

> > +config INTEL_TDX_GUEST
> > +	bool "Intel TDX (Trust Domain Extensions) - Guest Support"
> > +	depends on X86_64 && CPU_SUP_INTEL
> > +	depends on X86_X2APIC
> > +	help
> > +	  Support running as a guest under Intel TDX.  Without this support,
> > +	  the guest kernel can not boot or run under TDX.
> > +	  TDX includes memory encryption and integrity capabilities
> > +	  which protect the confidentiality and integrity of guest
> > +	  memory contents and CPU state. TDX guests are protected from
> > +	  potential attacks from the VMM.
> > +

-- 
 Kirill A. Shutemov