[PATCH] iommu/arm-smmu-v3: Make the kunit into a module

[Will Deacon]

On Tue, May 07, 2024 at 10:21:10AM -0300, Jason Gunthorpe wrote:
> It turns out kconfig has problems ensuring the SMMU module and the KUNIT
> module are consistently y/m to allow linking. It will permit KUNIT to be a
> module while SMMU is built in.
> 
> Also, Fedora apparently enables kunit on production kernels.
> 
> So, put the entire kunit in its own module using the
> VISIBLE_IF_KUNIT/EXPORT_SYMBOL_IF_KUNIT machinery. This keeps it out of
> vmlinus on Fedora and makes the kconfig work in the normal way. There is
> no cost if kunit is disabled.
> 
> Fixes: 56e1a4cc2588 ("iommu/arm-smmu-v3: Add unit tests for arm_smmu_write_entry")
> Reported-by: Thorsten Leemhuis <linux at leemhuis.info>
> Link: https://lore.kernel.org/all/aeea8546-5bce-4c51-b506-5d2008e52fef@leemhuis.info
> Signed-off-by: Jason Gunthorpe <jgg at nvidia.com>
> ---
>  drivers/iommu/Kconfig                            | 2 +-
>  drivers/iommu/arm/arm-smmu-v3/Makefile           | 3 ++-
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c  | 1 +
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c | 3 +++
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c      | 8 ++++++++
>  5 files changed, 15 insertions(+), 2 deletions(-)
> 
> Joerg, can you pick this to solve the linux-next issue for Thorsten?
> 
> Thanks,
> Jason
> 
> diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
> index 66325210c8c986..c04584be30893f 100644
> --- a/drivers/iommu/Kconfig
> +++ b/drivers/iommu/Kconfig
> @@ -415,7 +415,7 @@ config ARM_SMMU_V3_SVA
>  	  and PRI.
>  
>  config ARM_SMMU_V3_KUNIT_TEST
> -	bool "KUnit tests for arm-smmu-v3 driver"  if !KUNIT_ALL_TESTS
> +	tristate "KUnit tests for arm-smmu-v3 driver"  if !KUNIT_ALL_TESTS
>  	depends on KUNIT
>  	depends on ARM_SMMU_V3_SVA
>  	default KUNIT_ALL_TESTS

Would it work to leave this as 'bool' and have something like:

	depends on KUNIT=y

instead? That would be a lot simpler and avoids all the conditional
symbol exports.

Will