Re: [PATCH v3 05/17] KVM: x86/pmu: Reprogram guest PEBS event to emulate guest PEBS counter

Peter Zijlstra
2021-01-15T11:36:43Z

On Mon, Jan 04, 2021 at 09:15:30PM +0800, Like Xu wrote:
> When a guest counter is configured as a PEBS counter through
> IA32_PEBS_ENABLE, a guest PEBS event will be reprogrammed by
> configuring a non-zero precision level in the perf_event_attr.
>
> The guest PEBS overflow PMI bit would be set in the guest
> GLOBAL_STATUS MSR when PEBS facility generates a PEBS
> overflow PMI based on guest IA32_DS_AREA MSR.
>
> The attr.precise_ip would be adjusted to a special precision
> level when the new PEBS-PDIR feature is supported later which
> would affect the host counters scheduling.

This seems like a random collection of changes, all required, but
loosely related.

> The guest PEBS event would not be reused for non-PEBS
> guest event even with the same guest counter index.

/me rolls eyes at the whole destroy+create nonsense...