Re: [PATCH 00/33] vfio: Introduce selftests for VFIO

[Alex Williamson <alex.williamson@redhat.com>]

On Mon, 18 Aug 2025 13:33:52 -0700
David Matlack <dmatlack@google.com> wrote:

> On Mon, Aug 18, 2025 at 12:37 PM Alex Williamson
> <alex.williamson@redhat.com> wrote:
> >
> > On Mon, 18 Aug 2025 11:59:39 -0700
> > David Matlack <dmatlack@google.com> wrote:
> >  
> > > On Thu, Jul 31, 2025 at 1:55 PM David Matlack <dmatlack@google.com> wrote:  
> > > >
> > > > On Tue, Jul 29, 2025 at 3:26 PM Jason Gunthorpe <jgg@nvidia.com> wrote:  
> > > > >
> > > > > On Mon, Jul 28, 2025 at 10:27:37AM -0600, Alex Williamson wrote:  
> > > > > > On Fri, 25 Jul 2025 09:47:48 -0700
> > > > > > David Matlack <dmatlack@google.com> wrote:  
> > > > > > > I also was curious about your thoughts on maintenance of VFIO
> > > > > > > selftests, since I don't think we discussed that in the RFC. I am
> > > > > > > happy to help maintain VFIO selftests in whatever way makes the most
> > > > > > > sense. For now I added tools/testing/selftests/vfio under the
> > > > > > > top-level VFIO section in MAINTAINERS (so you would be the maintainer)
> > > > > > > and then also added a separate section for VFIO selftests with myself
> > > > > > > as a Reviewer (see PATCH 01). Reviewer felt like a better choice than
> > > > > > > Maintainer for myself since I am new to VFIO upstream (I've primarily
> > > > > > > worked on KVM in the past).  
> > > > > >
> > > > > > Hi David,
> > > > > >
> > > > > > There's a lot of potential here and I'd like to see it proceed.  
> > > > >
> > > > > +1 too, I really lack time at the moment to do much with this but I'm
> > > > > half inclined to suggest Alex should say it should be merged in 6
> > > > > weeks (to motivate any reviewing) and we can continue to work on it
> > > > > in-tree.
> > > > >
> > > > > As they are self tests I think there is alot more value in having the
> > > > > tests than having perfect tests.  
> > > >
> > > > They have been quite useful already within Google. Internally we have
> > > > something almost identical to the RFC and have been using that for
> > > > testing our 6.6-based kernel continuously since March. Already they
> > > > have caught one (self-inflicted) regression where 1GiB HugeTLB pages
> > > > started getting mapped with 2MiB mappings in the IOMMU, and have been
> > > > very helpful with new development (e.g. Aaron's work, and Live Update
> > > > support).
> > > >
> > > > So I agree, it's probably net positive to merge early and then iterate
> > > > in-tree. Especially since these are only tests and not e.g.
> > > > load-bearing kernel code (although I still want to hold a high bar for
> > > > the selftests code).
> > > >
> > > > The only patches to hold off merging would be 31-33, since those
> > > > should probably go through the KVM tree? And of course we need Acks
> > > > for the drivers/dma/{ioat,idxd} changes, but the changes there are
> > > > pretty minor.  
> > >
> > > Alex, how would you like to proceed?  
> >
> > I think we need an ack from Shuah for the overall inclusion in
> > tools/testing/selftests/
> >
> > AFAICT the tools include files don't seem to have any central
> > authority, so maybe we just need to chase those ioat/idxd acks, along
> > with Shuah's and we can get this rolling and follow-up with the latter
> > KVM patches once the base is merged.  Thanks,  
> 
> Sounds good.
> 
> And yeah, I also don't see any maintainers listed for tools/include/
> or tools/arch/x86/include/. Jason left some comments on the RFC that
> reduced the delta in v1, but that's the only feedback I've gotten so
> far there.
> 
> I will try emailing Shuah and the ioat/idxd maintainers directly as a
> next step, since it has been about 2 months since I posted this series
> and we haven't heard anything yet.
> 
> Thanks for the help.

I think we have all the required acks now and reviews just suggest some
minor patch shuffling, right?.  You were also going to switch from
reviewer to maintainer of the selftests in MAINTAINERS ;)

Are you planning to collect those acks, add the minor changes, drop the
trailing KVM changes to come in through the existing kvm selftests and
repost?

With KVM Forum coming up, I'd like to try to get this squared away and
into the vfio next branch by next week.  Thanks,

Alex