Re: [PATCH v6 06/10] vfio: selftests: Allow drivers to specify required region size

[Jason Gunthorpe <jgg@nvidia.com>]

On Fri, Sep 18, 2026 at 07:58:58AM -0700, David Matlack wrote:
> > >
> > > [Severity: Medium]
> > > Since this changes the vfio test to use the dynamic driver->region.size
> > > instead of SZ_2M, should tools/testing/selftests/kvm/irq_test.c be updated
> > > as well?
> > >
> > > It looks like vfio_setup_msi() in kvm/irq_test.c still forcefully overwrites
> > > the dynamically probed size back to 2MB:
> > >
> > > tools/testing/selftests/kvm/irq_test.c:vfio_setup_msi() {
> > >       ...
> > >       region = &device->driver.region;
> > >       region->size = SZ_2M;
> > >       region->iova = iova_allocator_alloc(allocator, region->size);
> > >       ...
> > > }
> > >
> > > Will this cause the KVM irq_test to fail with a VFIO_ASSERT_GE during driver
> > > initialization via vfio_pci_driver_init() when tested with a driver that
> > > requires a larger region, such as the mlx5 driver mentioned in the commit
> > > message?
> >
> > I have no idea, Dave? Did kvm start using this stuff?
> 
> Yes, KVM started linking in the VFIO selftests library in 7.3 and
> irq_test.c is the first test using it.

Okay, so I think this is all that is needed:

@@ -101,7 +100,6 @@ static int vfio_setup_msi(struct vfio_pci_device *device)
        allocator = iova_allocator_init(device->iommu);
 
        region = &device->driver.region;
-       region->size = SZ_2M;
        region->iova = iova_allocator_alloc(allocator, region->size);
        region->vaddr = kvm_mmap(region->size, prot, flags, -1);
        TEST_ASSERT(region->vaddr != MAP_FAILED, "mmap() failed\n");

> Looks like that is also causing the dma_rmb/wmb() redefinition
> compiler warning from the kernel-test-robot.

Yeah, for some reason kvm defined them in its private headers instead
of putting them in the right place :(

I think I can just delete the kvm definitions.

I don't have an arm system or userspace cross compiler to test it with
though..

Are we good on everything else, can Alex pick it up after I fix this?

Jason