Re: [PATCH v3 00/16] KVM: arm64: nv: Shadow stage-2 page table handling

Darren Hart
2024-12-05T18:18:24Z

On Sat, Nov 23, 2024 at 09:49:08AM +0000, Marc Zyngier wrote:
> On Fri, 22 Nov 2024 19:04:47 +0000,
> Marc Zyngier <maz@kernel.org> wrote:
> >
> > On Fri, 22 Nov 2024 16:54:16 +0000,
> > Ganapatrao Kulkarni <gankulkarni@os.amperecomputing.com> wrote:
> > >
> > >
> > >
> > > On 21-11-2024 10:14 pm, Marc Zyngier wrote:
> > > > On Thu, 21 Nov 2024 08:11:00 +0000,
> > > > Ganapatrao Kulkarni <gankulkarni@os.amperecomputing.com> wrote:
> > > >
> > > > Hi Ganapatrao,
> > > >
> > > >> IIRC, Most of the patches that are specific to NV have been merged
> > > >> upstream. However I do see that, some of the vGIC and Timer related
> > > >> patches are still in your private NV repository. Can these patches be
> > > >> prioritized to upstream, so that we can have have the first working
> > > >> version of NV on mainline.
> > > >
> > > > Who is *we*?
> > > >
> > > > Things get upstreamed when we (people doing the actual work) decide
> > > > they are ready. At the moment, they are not.
> > > >
> > > > Also, while I enjoy working on NV, this isn't *my* priority.
> > >
> > > Sure, I understand that it's not your priority right now. I'm happy
> > > to spend some time on it, please do let us know in what areas/patches
> > > needs attention before the code would be ready to merge?
> >
> > Please understand that NV isn't special, and while there is still a
> > bunch of things that need to be merged, it is the whole of KVM/arm64
> > that needs attention.
> >
> > For example, there is the debug series from Oliver, the feature
> > handling from Fuad. They may not have NV written all over them, but
> > they do have an impact on the NV behaviour one way or another.
> >
> > By paying attention to these series, you would help with the
> > groundwork that is required before we can actually enable NV. This is
> > what matters now, not the next 50 or so NV-specific patches.
>
> And one last thing, while I think of it: NV is very unlikely to get
> merged without a testing infrastructure. Which means that the current
> selftests must run at EL2, and that *new* selftests must be created to
> test the NV implementation (all the trap behaviours, for example).
>
> So if you (and I assume your employer, as you keep using the plural)
> want to help moving NV support upstream, this is an area where you
> could help and make a massive difference.

Appreciate the specific examples Marc, thank you. I'll work with my team
at Ampere in this direction - specifically the testing infrastructure
work and engaging in the NV-adjacent kvm patche series.

--
Darren Hart
Ampere Computing / Linux Enabling