Re: [PATCH 00/18] KVM: arm64: Support FEAT_PMUv3 on Apple hardware

[Marc Zyngier]

On Wed, 08 Jan 2025 20:14:07 +0000,
Oliver Upton <oliver.upton@xxxxxxxxx> wrote:
> 
> Hey Will,
> 
> On Wed, Jan 08, 2025 at 12:38:41PM +0000, Will Deacon wrote:
> > What's your plan for this series? I started looking at it and I can take
> > the first four apple_m1 patches if you like?
> 
> I plan on posting a respin of it by next week, which should look pretty
> much the same besides cleaning up the build error I introduced :)
> 
> Besides that, I think we need to decide on the KVM side of things
> whether or not we want to support an event counter in addition to the
> PMU cycle counter. Janne's FEX use case would certainly benefit from it.

I think we should always be able to support *one* counter on top of
the cycle counter. Doing more than that would result in inconsistent
behaviours (some events only count on a single counter).

Unless we restrict ourselves to a very small set of events that we can
always schedule on any counter, but this doesn't sound very promising.

Thoughts?

	M.

-- 
Without deviation from the norm, progress is not possible.