Re: [PATCH v7 05/13] perf/x86/intel/pt: Introduce a new function to get capability of Intel PT

[Alexander Shishkin]

On Thu, May 03, 2018 at 11:04:52AM +0000, Kang, Luwei wrote:
> > > New function __pt_cap_get() will be invoked in KVM to check if a
> > > specific capability is availiable in KVM guest.
> > > Another function pt_cap_get() can only check the hardware capabilities
> > > but this may different with KVM guest because some features may not be
> > > exposed to guest.
> > 
> > Do we really need both in KVM?
> 
> Yes, KVM need get host capability to estimate if can expose this feature
> to guest

Can you elaborate on this, what information do we need besides
MSR_IA32_VMX_MISC[14]?

Thanks,
--
Alex