[Bug 218792] Guest call trace with mwait enabled

bugzilla-daemon
2025-08-08T22:59:33Z

--- Comment #7 from Sean Christopherson (seanjc@google.com) ---
On Fri, Aug 08, 2025, bugzilla-daemon@kernel.org wrote:
> https://bugzilla.kernel.org/show_bug.cgi?id=218792
>
> Len Brown (lenb@kernel.org) changed:
>
> What |Removed |Added
> ----------------------------------------------------------------------------
> CC| |lenb@kernel.org
>
> --- Comment #6 from Len Brown (lenb@kernel.org) ---
> Re: intel_idle
>
> I agree that the SDM doesn't guarantee this MSR exists
> based on the presence of PC10.
>
> I'm not opposed to _safe().
>
> but...
>
> Why is this "platform" advertising PC10 (or any MWAIT C-states) to intel_idle
> in the first place?

Because letting the guest execute MONITOR/MWAIT natively, and thus get into
deeper
sleep states, is advantageous for all the same reasons bare metal CPUs want to
get into deep sleep states, e.g. to let active cores hit higher turbo bins.