[PATCH v3 00/20] iommu: Retire detach_dev callback

[Lu Baolu]

Hi folks,

The iommu core calls the driver's detach_dev domain op callback only when
a device is finished assigning to user space and
iommu_group_release_dma_owner() is called to return the device to the
kernel, where iommu core wants to set the default domain to the device but
the driver didn't provide one. The code looks like:

        /*
         * New drivers should support default domains and so the detach_dev() op
         * will never be called. Otherwise the NULL domain represents some
         * platform specific behavior.
         */
        if (!new_domain) {
                if (WARN_ON(!group->domain->ops->detach_dev))
                        return -EINVAL;
                __iommu_group_for_each_dev(group, group->domain,
                                           iommu_group_do_detach_device);
                group->domain = NULL;
                return 0;
        }

In other words, if the iommu driver provides default domains, the
.detach_dev callback will never be called; Otherwise, the .detach_dev
callback is actually called to return control back to the platform DMA
ops, other than detaching the domain from device.

This series cleanups this by:

- If the IOMMU driver provides default domains, remove .detach_dev
  callback.
- Adds a new set_platform_dma iommu op. Any IOMMU driver that doesn't
  provide default domain should implement set_platform_dma callback
  instead.
- Retire .detach_dev callback and rename .attach_dev to .set_dev.

This series originates from various discussion in the community. Thank
Jason, Robin and all others for their ideas. This series looks very
long. It is necessary because I hope that change in each driver has a
confirmation from its stakeholder. I will then be able to merge some of
them to make the series cute.

The whole series is available on github:
https://github.com/LuBaolu/intel-iommu/commits/iommu-retire-detach_dev-v3

Please review and suggest.

Best regards,
baolu

Change log:
v3:
 - Setting blocking domain is not conceptually equal to detach_dev.
   Dropped all blocking domain related staffs in the previous version.

v2:
 - https://lore.kernel.org/linux-iommu/20220826123014.52709-1-baolu.lu@xxxxxxxxxxxxxxx/
 - Replace .detach_dev callback with static block domain ops;
 - Rename .attach_dev to .set_dev.

v1:
 - https://lore.kernel.org/linux-iommu/20220516015759.2952771-1-baolu.lu@xxxxxxxxxxxxxxx/

Lu Baolu (20):
  iommu/amd: Remove detach_dev callback
  iommu/apple-dart: Remove detach_dev callback
  iommu/qcom: Remove detach_dev callback
  iommu/exynos: Remove detach_dev callback
  iommu/ipmmu: Remove detach_dev callback
  iommu/mtk: Remove detach_dev callback
  iommu/rockchip: Remove detach_dev callback
  iommu/sprd: Remove detach_dev callback
  iommu/sun50i: Remove detach_dev callback
  iommu: Add set_platform_dma iommu ops
  iommu/fsl_pamu: Add set_platform_dma callback
  iommu/msm: Add set_platform_dma callback
  iommu/mtk_v1: Add set_platform_dma callback
  iommu/omap: Add set_platform_dma callback
  iommu/s390: Add set_platform_dma callback
  iommu/gart: Add set_platform_dma callback
  iommu/tegra: Add set_platform_dma callback
  iommu: Call set_platform_dma if default domain is unavailable
  iommu: Retire detach_dev callback
  iommu: Rename attach_dev to set_dev

 include/linux/iommu.h                       | 10 ++++---
 drivers/iommu/amd/iommu.c                   | 28 +-----------------
 drivers/iommu/apple-dart.c                  | 19 +-----------
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c |  2 +-
 drivers/iommu/arm/arm-smmu/arm-smmu.c       |  2 +-
 drivers/iommu/arm/arm-smmu/qcom_iommu.c     | 25 +---------------
 drivers/iommu/exynos-iommu.c                |  3 +-
 drivers/iommu/fsl_pamu_domain.c             | 12 ++++++--
 drivers/iommu/intel/iommu.c                 |  4 +--
 drivers/iommu/iommu.c                       | 32 +++++++--------------
 drivers/iommu/ipmmu-vmsa.c                  | 18 +-----------
 drivers/iommu/msm_iommu.c                   | 12 ++++++--
 drivers/iommu/mtk_iommu.c                   | 11 +------
 drivers/iommu/mtk_iommu_v1.c                | 12 ++++++--
 drivers/iommu/omap-iommu.c                  | 12 ++++++--
 drivers/iommu/rockchip-iommu.c              |  3 +-
 drivers/iommu/s390-iommu.c                  | 12 ++++++--
 drivers/iommu/sprd-iommu.c                  | 18 +-----------
 drivers/iommu/sun50i-iommu.c                |  3 +-
 drivers/iommu/tegra-gart.c                  | 12 ++++++--
 drivers/iommu/tegra-smmu.c                  | 12 ++++++--
 drivers/iommu/virtio-iommu.c                |  2 +-
 22 files changed, 100 insertions(+), 164 deletions(-)

-- 
2.34.1