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

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] selftests: kvm/irq_test overwrites dynamic driver region size
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commit 97ad8ed7fec97be65848236fd1c8afab2ff66a54
Author: Jason Gunthorpe <jgg@ziepe.ca>

vfio: selftests: Allow drivers to specify required region size

This commit adds a region_size field to struct vfio_pci_driver_ops to let
drivers declare their required DMA-mapped region size. It updates the core
driver probe and the vfio_pci_driver_test to use this dynamically probed
size instead of hardcoding 2MB.

> diff --git a/tools/testing/selftests/vfio/vfio_pci_driver_test.c b/tools/testing/selftests/vfio/vfio_pci_driver_test.c
> index 761bf117d624f..2bd949aafd731 100644
> --- a/tools/testing/selftests/vfio/vfio_pci_driver_test.c
> +++ b/tools/testing/selftests/vfio/vfio_pci_driver_test.c
> @@ -87,7 +87,8 @@ FIXTURE_SETUP(vfio_pci_driver_test)
>  	driver = &self->device->driver;
>  
>  	region_setup(self->iommu, self->iova_allocator, &self->memcpy_region, SZ_1G);
> -	region_setup(self->iommu, self->iova_allocator, &driver->region, SZ_2M);
> +	region_setup(self->iommu, self->iova_allocator, &driver->region,
> +		     driver->region.size);

[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?

>  
>  	/* Any IOVA that doesn't overlap memcpy_region and driver->region. */

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Sashiko AI review · https://sashiko.dev/#/patchset/0-v6-8af36cf7b73f+e2-mlx5st_jgg@nvidia.com?part=6