Re: [PATCH v4 10/19] x86/cpu: Detect VMX features on Intel, Centaur and Zhaoxin CPUs

Borislav Petkov
2019-12-12T18:25:01Z

On Thu, Dec 12, 2019 at 09:55:11AM -0800, Sean Christopherson wrote:
> The reasoning behind using vanilla rdmsr() on PROC and PIN controls is that
> those MSRs should exist on any CPU that supports VMX, i.e. we want the WARN.
>
> The alternative would be to use rdmsr_safe() for everything and then
> explicitly disable VMX if a fault on PROC or PIN occurs, but that circles
> us back to the handling a fault on rdmsr(MSR_IA32_FEAT_CTL), i.e. is it
> really worth gracefully handling a fault that should never occur?

No but pls put a comment above it explaining why we're doing rdmsr()
only with those two MSRs.

Thx.

--
Regards/Gruss,
Boris.