Re: [PATCH 1/6] x86/feat_ctl: Add new VMX feature, Tertiary VM-Execution control

[Paolo Bonzini]

On 29/07/21 01:44, Sean Christopherson wrote:
> > +	rdmsr_safe(MSR_IA32_VMX_PROCBASED_CTLS3, &ign, &supported);
> > +	c->vmx_capability[TERTIARY_CTLS_LOW] = ign;
> > +	c->vmx_capability[TERTIARY_CTLS_HIGH] = supported;
> Assuming only the lower 32 bits are going to be used for the near future (next
> few years), what about defining just TERTIARY_CTLS_LOW and then doing:
>
> 	/*
> 	 * Tertiary controls are 64-bit allowed-1, so unlikely other MSRs, the
> 	 * upper bits are ignored (because they're not used, yet...).
> 	 */
> 	rdmsr_safe(MSR_IA32_VMX_PROCBASED_CTLS3, &supported, &ign);
> 	c->vmx_capability[TERTIARY_CTLS_LOW] = supported;
>
> I.e. punt the ugliness issue down the road a few years.

Or use two new variables low/high instead of supported/ign.

Paolo