[PATCH 0/2] KVM: PPC: support kvm selftests

[Nicholas Piggin]

On Thu Mar 23, 2023 at 3:41 AM AEST, Sean Christopherson wrote:
> On Thu, Mar 16, 2023, Michael Ellerman wrote:
> > Nicholas Piggin <npiggin at gmail.com> writes:
> > > Hi,
> > >
> > > This series adds initial KVM selftests support for powerpc
> > > (64-bit, BookS).
> > 
> > Awesome.
> >  
> > > It spans 3 maintainers but it does not really
> > > affect arch/powerpc, and it is well contained in selftests
> > > code, just touches some makefiles and a tiny bit headers so
> > > conflicts should be unlikely and trivial.
> > >
> > > I guess Paolo is the best point to merge these, if no comments
> > > or objections?
> > 
> > Yeah. If it helps:
> > 
> > Acked-by: Michael Ellerman <mpe at ellerman.id.au> (powerpc)
>
> What is the long term plan for KVM PPC maintenance?  I was under the impression
> that KVM PPC was trending toward "bug fixes only", but the addition of selftests
> support suggests otherwise.

We plan to continue maintaining it. New support and features has been a
bit low in the past couple of years, hopefully that will pick up a bit
though.

> I ask primarily because routing KVM PPC patches through the PPC tree is going to
> be problematic if KVM PPC sees signficiant development.  The current situation is
> ok because the volume of patches is low and KVM PPC isn't trying to drive anything
> substantial into common KVM code, but if that changes... 

Michael has done KVM topic branches to pull from a few times when such
conflicts came up (at smaller scale). If we end up with larger changes
or regular conflicts we might start up a kvm-ppc tree again I guess.

> My other concern is that for selftests specifically, us KVM folks are taking on
> more maintenance burden by supporting PPC.  AFAIK, none of the people that focus
> on KVM selftests in any meaningful capacity have access to PPC hardware, let alone
> know enough about the architecture to make intelligent code changes.
>
> Don't get me wrong, I'm very much in favor of more testing, I just don't want KVM
> to get left holding the bag.

Understood. I'll be happy to maintain powerpc part of kvm selftests and
do any fixes that are needed for core code changes.If support fell away
you could leave it broken (or rm -rf it if you prefer) -- I wouldn't ask
anybody to work on archs they don't know or aren't paid to.

Not sure if anything more can be done to help your process or ease your
mind. It (KVM and kvm-selftests) can run in QEMU at least.

Thanks,
Nick