Re: [PATCH 00/67] KVM: iommu: Overhaul device posted IRQs support

[David Matlack <dmatlack@google.com>]

On Tue, Apr 8, 2025 at 10:13 AM David Matlack <dmatlack@google.com> wrote:
>
> On Fri, Apr 4, 2025 at 12:39 PM Sean Christopherson <seanjc@google.com> wrote:
> >
> > This series is well tested except for one notable gap: I was not able to
> > fully test the AMD IOMMU changes.  Long story short, getting upstream
> > kernels into our full test environments is practically infeasible.  And
> > exposing a device or VF on systems that are available to developers is a
> > bit of a mess.
> >
> > The device the selftest (see the last patch) uses is an internel test VF
> > that's hosted on a smart NIC using non-production (test-only) firmware.
> > Unfortunately, only some of our developer systems have the right NIC, and
> > for unknown reasons I couldn't get the test firmware to install cleanly on
> > Rome systems.  I was able to get it functional on Milan (and Intel CPUs),
> > but APIC virtualization is disabled on Milan.  Thanks to KVM's force_avic
> > I could test the KVM flows, but the IOMMU was having none of my attempts
> > to force enable APIC virtualization against its will.
>
> (Sean already knows this but just sharing for the broader visibility.)
>
> I am working on a VFIO selftests framework and helper library that we
> can link into the KVM selftests to make this kind of testing much
> easier. It will support a driver framework so we can support testing
> against different devices in a common way. Developers/companies can
> carry their own out-of-tree drivers for non-standard/custom test
> devices, e.g. the "Mercury device" used in this series.
>
> I will send an RFC in the coming weeks. If/when my proposal is merged,
> then I think we'll have a clean way to get the vfio_irq_test merged
> upstream as well.

This RFC can be found here:
https://lore.kernel.org/kvm/20250523233018.1702151-1-dmatlack@google.com/