Re: [PATCH v4 16/17] kvm: x86: Add support IA32_CORE_CAPABILITY MSR

Xiaoyao Li
2019-03-08T08:03:24Z

On Fri, 2019-03-08 at 08:54 +0100, Paolo Bonzini wrote:
> On 08/03/19 07:10, Xiaoyao Li wrote:
> > > so that non-virtualizable features are hidden and
> > >
> > > if (boot_cpu_has(X86_FEATURE_SPLIT_LOCK_DETECT))
> > > data |= CORE_CAP_SPLIT_LOCK_DETECT;
> > >
> > > so that userspace gets "for free" the FMS list that will be added
> > > later to the kernel.
> >
> > I think it's redundant. Because there is no case that
> > rdmsrl_safe(MSR_IA32_CORE_CAPABILITY, &data) shows no split lock detection
> > while
> > boot_cpu_has(X86_FEATURE_SPLIT_LOCK_DETECT).
>
> There will be when the kernel will add a list of FMS values that have
> split lock detection but lack the core capabilities MSR. Or at least
> that is what Fenghua said in the cover letter.
>
> Paolo

Got it.
Thanks for your explanation.