Re: [PATCH v2] x86/cpuid: Advertise no-lmsl unilaterally to hvm guests

[Jan Beulich <jbeulich@xxxxxxxx>]

On 12.04.2021 17:06, Andrew Cooper wrote:
> While part of the original AMD64 spec, Long Mode Segment Limit was a feature
> not picked up by Intel, and therefore didn't see much adoption in software.
> AMD have finally dropped the feature from hardware, and allocated a CPUID bit
> to indicate its absence.
> 
> Xen has never supported the feature for guests, even when running on capable
> hardware, so advertise the feature's absence unilaterally.
> 
> There is nothing specifically wrong with exposing this bit to PV guests, but
> the PV ABI doesn't include a working concept of MSR_EFER in the first place,
> so exposing it to PV guests would be out-of-place.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>