Re: [PATCH v1 1/1] x86/tdx: Handle MWAIT, MONITOR and WBINVD

[Kuppuswamy, Sathyanarayanan]

On 3/30/21 8:10 AM, Dave Hansen wrote:
> On 3/30/21 8:00 AM, Andi Kleen wrote:
> > > > +	/* MWAIT is not supported in TDX platform, so suppress it */
> > > > +	setup_clear_cpu_cap(X86_FEATURE_MWAIT);
> > > In fact, MWAIT bit returned by CPUID instruction is zero for TD guest. This
> > > is enforced by SEAM module.
> > Good point.
> > > Do we still need to safeguard it by setup_clear_cpu_cap() here?
> > I guess it doesn't hurt to do it explicitly.
>
> If this MWAIT behavior (clearing the CPUID bit) is part of the guest
> architecture, then it would also be appropriate to WARN() rather than
> silently clearing the X86_FEATURE bit.
Makes sense. It will be useful to find the problem with TDX Module.
>

--
Sathyanarayanan Kuppuswamy
Linux Kernel Developer