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

[David Matlack <dmatlack@google.com>]

On Mon, May 26, 2025 at 2:07 AM Yi Liu <yi.l.liu@intel.com> wrote:
>
> On 2025/5/24 07:29, David Matlack wrote:
> > This series introduces VFIO selftests, located in
> > tools/testing/selftests/vfio/.
> >
> > VFIO selftests aim to enable kernel developers to write and run tests
> > that take the form of userspace programs that interact with VFIO and
> > IOMMUFD uAPIs. VFIO selftests can be used to write functional tests for
> > new features, regression tests for bugs, and performance tests for
> > optimizations.
> >
> > These tests are designed to interact with real PCI devices, i.e. they do
> > not rely on mocking out or faking any behavior in the kernel. This
> > allows the tests to exercise not only VFIO but also IOMMUFD, the IOMMU
> > driver, interrupt remapping, IRQ handling, etc.
> >
> > We chose selftests to host these tests primarily to enable integration
> > with the existing KVM selftests. As explained in the next section,
> > enabling KVM developers to test the interaction between VFIO and KVM is
> > one of the motivators of this series.
>
> interesting. Two quick questions:
> 1) does this selftest support all the vfio iommu drivers (typ1 and
> spapr_tce)? Maybe also the iommufd vfio_compat as well.

This series supports the following IOMMU drivers [1]:
  - VFIO Type1 IOMMU
  - VFIO Type1v2 IOMMU
  - IOMMUFD compat-mode with Type1
  - IOMMUFD compat-mode with Type1v2
  - IOMMUFD

I have not lookied at spapr_tce or any other modes, but I implemented
the code in such a way that other modes could be added in the future.

[1] https://github.com/dmatlack/linux/blob/9832935d7a44aab725ff627c6acf22b8a17d407f/tools/testing/selftests/vfio/lib/vfio_pci_device.c#L409

> 2) I know Alex has a test suit as the below. Has this series referred
>     it?
>
> https://github.com/awilliam/tests/commits/for-clg/

I was not aware of these tests, thanks for sharing the link.

If we think the approach taken in this series makes sense, we could
presumably port those tests to tools/testing/selftests/vfio/. I would
be happy to help with that.