Re: [PATCH] iommu/s390: Get rid of S390_CCW_IOMMU

[Eric Farman <farman@linux.ibm.com>]

On Fri, 2023-04-28 at 16:28 -0300, Jason Gunthorpe wrote:
> This doesn't do anything anymore, the only user of the symbol was
> VFIO_CCW
> which already "depends on VFIO" and VFIO selects IOMMU_API.

The "depends on VFIO" statement came from commit de858a05c9d8 ("vfio-
mdev: add back CONFIG_VFIO dependency"). This isn't really a fix to
that one, but it does follow that set of changes.

> 
> When this was added VFIO was wrongly doing "depends on IOMMU_API"

(later fixed by commit 179209fa1270 ("vfio: IOMMU_API should be
selected"))

> which
> required some mess like this to ensure IOMMU_API was turned on.
> 
> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

What of S390_AP_IOMMU? Seems to have been borrowed from the _CCW hunks
being removed here, and is now equally redundant (though I have not
tried).

Regardless, for this:

Reviewed-by: Eric Farman <farman@linux.ibm.com>

> ---
>  arch/s390/Kconfig                 | 1 -
>  arch/s390/configs/debug_defconfig | 1 -
>  arch/s390/configs/defconfig       | 1 -
>  drivers/iommu/Kconfig             | 8 --------
>  4 files changed, 11 deletions(-)
> 
> diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
> index 9809c74e124060..9334500078f978 100644
> --- a/arch/s390/Kconfig
> +++ b/arch/s390/Kconfig
> @@ -714,7 +714,6 @@ config EADM_SCH
>  config VFIO_CCW
>         def_tristate n
>         prompt "Support for VFIO-CCW subchannels"
> -       depends on S390_CCW_IOMMU
>         depends on VFIO
>         select VFIO_MDEV
>         help
> diff --git a/arch/s390/configs/debug_defconfig
> b/arch/s390/configs/debug_defconfig
> index 4ccf66d29fc24b..77b886e1b867d4 100644
> --- a/arch/s390/configs/debug_defconfig
> +++ b/arch/s390/configs/debug_defconfig
> @@ -591,7 +591,6 @@ CONFIG_VIRTIO_BALLOON=m
>  CONFIG_VIRTIO_INPUT=y
>  CONFIG_VHOST_NET=m
>  CONFIG_VHOST_VSOCK=m
> -CONFIG_S390_CCW_IOMMU=y
>  CONFIG_S390_AP_IOMMU=y
>  CONFIG_EXT4_FS=y
>  CONFIG_EXT4_FS_POSIX_ACL=y
> diff --git a/arch/s390/configs/defconfig
> b/arch/s390/configs/defconfig
> index 693297a2e89733..36ab9b1956245c 100644
> --- a/arch/s390/configs/defconfig
> +++ b/arch/s390/configs/defconfig
> @@ -580,7 +580,6 @@ CONFIG_VIRTIO_BALLOON=m
>  CONFIG_VIRTIO_INPUT=y
>  CONFIG_VHOST_NET=m
>  CONFIG_VHOST_VSOCK=m
> -CONFIG_S390_CCW_IOMMU=y
>  CONFIG_S390_AP_IOMMU=y
>  CONFIG_EXT4_FS=y
>  CONFIG_EXT4_FS_POSIX_ACL=y
> diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
> index db98c3f86e8c8b..b1f9d82b4ec9ae 100644
> --- a/drivers/iommu/Kconfig
> +++ b/drivers/iommu/Kconfig
> @@ -417,14 +417,6 @@ config S390_IOMMU
>         help
>           Support for the IOMMU API for s390 PCI devices.
>  
> -config S390_CCW_IOMMU
> -       bool "S390 CCW IOMMU Support"
> -       depends on S390 && CCW || COMPILE_TEST
> -       select IOMMU_API
> -       help
> -         Enables bits of IOMMU API required by VFIO. The iommu_ops
> -         is not implemented as it is not necessary for VFIO.
> -
>  config S390_AP_IOMMU
>         bool "S390 AP IOMMU Support"
>         depends on S390 && ZCRYPT || COMPILE_TEST
> 
> base-commit: 57d60ea1868f36586c85f6f6692cf4bc49affecd