Re: [PATCH v4 4/7] iommu: Pass in old domain to attach_dev callback functions

Jason Gunthorpe
2025-09-24T18:43:53Z

On Sun, Aug 31, 2025 at 04:31:56PM -0700, Nicolin Chen wrote:
> The IOMMU core attaches each device to a default domain on probe(). Then,
> every new "attach" operation has a fundamental meaning of two-fold:
> - detach from its currently attached (old) domain
> - attach to a given new domain
>
> Modern IOMMU drivers following this pattern usually want to clean up the
> things related to the old domain, so they call iommu_get_domain_for_dev()
> to fetch the old domain.
>
> Pass in the old domain pointer from the core to drivers, aligning with the
> set_dev_pasid op that passes in already.
>
> Ensure all low-level attach fcuntions in the core can forward the correct
> old domain pointer. Thus, rework those functions as well.
>
> Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> ---
> include/linux/iommu.h | 3 +-
> drivers/iommu/amd/iommu.c | 11 ++++---
> drivers/iommu/apple-dart.c | 9 +++--
> .../arm/arm-smmu-v3/arm-smmu-v3-iommufd.c | 5 +--
> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 33 ++++++++++++-------
> drivers/iommu/arm/arm-smmu/arm-smmu.c | 9 +++--
> drivers/iommu/arm/arm-smmu/qcom_iommu.c | 11 ++++---
> drivers/iommu/exynos-iommu.c | 6 ++--
> drivers/iommu/fsl_pamu_domain.c | 12 +++----
> drivers/iommu/intel/iommu.c | 10 ++++--
> drivers/iommu/intel/nested.c | 2 +-
> drivers/iommu/iommu.c | 26 +++++++++------
> drivers/iommu/iommufd/selftest.c | 2 +-
> drivers/iommu/ipmmu-vmsa.c | 10 +++---
> drivers/iommu/msm_iommu.c | 8 ++---
> drivers/iommu/mtk_iommu.c | 8 ++---
> drivers/iommu/mtk_iommu_v1.c | 7 ++--
> drivers/iommu/omap-iommu.c | 12 +++----
> drivers/iommu/riscv/iommu.c | 9 +++--
> drivers/iommu/rockchip-iommu.c | 20 ++++++++---
> drivers/iommu/s390-iommu.c | 9 +++--
> drivers/iommu/sprd-iommu.c | 3 +-
> drivers/iommu/sun50i-iommu.c | 8 +++--
> drivers/iommu/tegra-smmu.c | 10 +++---
> drivers/iommu/virtio-iommu.c | 6 ++--
> 25 files changed, 152 insertions(+), 97 deletions(-)

I've split things like this into more patches before, but this
actually isn't too bad, so I wouldn't push for it.

A series version would be:
- add a new op 'attach_dev2' or whatever
- Convert all drivers that just change the signature
- Convert drivers that have a trivial iommu_get_domain_for_dev()
- N patches to convert more complex drivers one by one
- Remove old op attach_dev

Again, looks Ok as-is:

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason