Re: [RFC PATCH 01/41] perf: x86/intel: Support PERF_PMU_CAP_VPMU_PASSTHROUGH

[Liang, Kan]

On 2024-04-11 1:04 p.m., Sean Christopherson wrote:
> On Fri, Jan 26, 2024, Xiong Zhang wrote:
>> From: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
>>
>> Define and apply the PERF_PMU_CAP_VPMU_PASSTHROUGH flag for the version 4
>> and later PMUs
> 
> Why?  I get that is an RFC, but it's not at all obvious to me why this needs to
> take a dependency on v4+.

The IA32_PERF_GLOBAL_STATUS_RESET/SET MSRs are introduced in v4. They
are used in the save/restore of PMU state. Please see PATCH 23/41.
So it's limited to v4+ for now.

Thanks,
Kan