Re: [PATCH] perf/x86: KVM: Disable vPMU support on hybrid CPUs (host PMUs)

From: Peter Zijlstra
Date: Tue Jan 31 2023 - 06:00:34 EST


On Tue, Jan 24, 2023 at 10:31:00AM -0500, Liang, Kan wrote:

> Yes, and also the CPUID leaf 0x23H support to enumerate the PMU features
> of each types.

Note that this is not enough or even useful. There is nothing that stops
a vCPU from migrating between types at every instruction. There simply
is no relation between a vCPU and a type, so knowing what a type does or
does not support is useless information.