Re: [PATCH v5 04/15] x86/mtrr: support setting MTRR state for software defined MTRRs

[Juergen Gross]

On 11.04.23 15:59, Michael Kelley (LINUX) wrote:
> From: Borislav Petkov <bp@xxxxxxxxx> Sent: Tuesday, April 11, 2023 6:21 AM
> > On Sat, Apr 01, 2023 at 08:36:41AM +0200, Juergen Gross wrote:
>
> [snip]
>
> > > +
> > > +	/*
> > > +	 * Only allowed for special virtualization cases:
> > > +	 * - when running as SEV-SNP guest
> > > +	 * - when running as Hyper-V isolated guest
> >
> > 	when running as a SEV-SNP guest on a HyperV with vTOM enabled
> >
> > that's a single condition.
> >
> > > +	 * - when running as Xen PV guest
> > > +	 * - when running as TSX guest
> > > +	 */
> > > +	if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP) &&
> > > +	    !hv_is_isolation_supported() &&
> > > +	    !cpu_feature_enabled(X86_FEATURE_XENPV) &&
> > > +	    !cpu_feature_enabled(X86_FEATURE_TDX_GUEST))
> >
> > IOW:
> >
> > 	if (!(hv_is_isolation_supported() && cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) &&
> > 	    !cpu_feature_enabled(X86_FEATURE_XENPV) &&
> > 	    !cpu_feature_enabled(X86_FEATURE_TDX_GUEST))
>
> That's doesn't work.  Hyper-V guests with vTOM don't have
> CC_ATTR_GUEST_SEV_SNP.

Yeah, the condition needs to be:

	if (!(hv_is_isolation_supported() ||
	      cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) &&
 	    !cpu_feature_enabled(X86_FEATURE_XENPV) &&
 	    !cpu_feature_enabled(X86_FEATURE_TDX_GUEST))

This is equivalent to the condition in my patch.


Juergen

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