Re: [PATCH] vfio: mlx5, pds: add IOMMU_SUPPORT dependency

[Jason Gunthorpe]

On Mon, Oct 23, 2023 at 01:55:03PM +0200, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@xxxxxxxx>
> 
> Selecting IOMMUFD_DRIVER is not allowed if IOMMUs themselves are not supported:
> 
> WARNING: unmet direct dependencies detected for IOMMUFD_DRIVER
>   Depends on [n]: IOMMU_SUPPORT [=n]
>   Selected by [m]:
>   - MLX5_VFIO_PCI [=m] && VFIO [=y] && PCI [=y] && MMU [=y] && MLX5_CORE [=y]
> 
> There is no actual build failure, only the warning.
> 
> Make the 'select' conditional using the same logic that we have for
> INTEL_IOMMU and AMD_IOMMU.
> 
> Fixes: 33f6339534287 ("vfio: Move iova_bitmap into iommufd")
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---
>  drivers/vfio/pci/mlx5/Kconfig | 2 +-
>  drivers/vfio/pci/pds/Kconfig  | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)

But this isn't the logic this wants, it wants to turn on
IOMMUFD_DRIVER if MLX5_VFIO_PCI is turned on.

I think it means IOMMUFD_DRIVER should be lifted out of the
IOMMU_SUPPORT block somehow. I guess just move it into the top of
drivers/iommu/Kconfig?

Jason