[PATCH v2 00/30] iommu: introduce iova_to_phys_length for efficient IOVA-to-physical translation

[Guanghui Feng <guanghuifeng@linux.alibaba.com>]

This series introduces the iova_to_phys_length interface across the IOMMU
subsystem. The new callback returns both the physical address and the PTE
mapping size in a single page table walk, enabling callers such as iommufd
and VFIO to traverse IOVA space efficiently by actual mapping granularity
instead of fixed PAGE_SIZE steps.

Motivation
==========

The current iova_to_phys interface only returns a physical address with no
indication of the mapping page size. This forces callers to iterate one
PAGE_SIZE at a time when collecting PFNs or unmapping IOVA ranges, which is
extremely inefficient for large mappings (e.g., 2MB or 1GB huge pages
require 512 or 262144 page-table walks respectively).

The new iova_to_phys_length interface solves this by providing the
contiguous mapping size alongside the physical address in a single walk.

Design
======

Core layer (patch 1):
  - Adds iova_to_phys_length to iommu_domain_ops
  - iommu_iova_to_phys_length() detects invalid states by checking
    ops->iova_to_phys_length (not domain->type), returns PHYS_ADDR_MAX
    on error
  - iommu_iova_to_phys() is preserved as a thin wrapper calling
    iova_to_phys_length internally, converting PHYS_ADDR_MAX back to 0
    for historical API compatibility

io-pgtable backends (patches 2-4):
  - ARM LPAE, ARM v7s, and DART each implement iova_to_phys_length
    returning phys + page size, with PHYS_ADDR_MAX for error paths
  - The old iova_to_phys is kept temporarily as a wrapper

generic_pt framework (patch 5):
  - Implements iova_to_phys_length using pt_entry_oa_lg2sz() which
    already accounts for contiguous PTE hints, returning the correct
    mapping size in a single leaf-entry lookup

Per-driver migration (patches 6-22):
  - Each IOMMU driver (arm-smmu-v3, arm-smmu, qcom, apple-dart,
    ipmmu-vmsa, mtk, exynos, fsl_pamu, msm, omap, rockchip, s390,
    sprd, sun50i, tegra-smmu, virtio) implements iova_to_phys_length
    in its own atomic commit
  - All error paths return PHYS_ADDR_MAX

Caller conversion (patches 23-25):
  - iommufd/pages.c uses iova_to_phys_length to batch PFN collection
    by actual mapping granularity
  - VFIO type1 uses iova_to_phys_length for efficient unmap traversal
  - drm/panfrost and drm/panthor switch to the new interface

Cleanup (patches 26-30):
  - io-pgtable selftests switch to iova_to_phys_length
  - Remove deprecated iova_to_phys wrappers from io-pgtable backends
  - Remove iova_to_phys from iommu_domain_ops and io_pgtable_ops

Changes in v2:
  - Use PHYS_ADDR_MAX (~(phys_addr_t)0) as error return instead of 0
    throughout the entire call chain, per review feedback (Jason)
  - Detect invalid domain states by checking ops->iova_to_phys_length
    rather than domain->type == IOMMU_DOMAIN_BLOCKED (Jason)
  - iommu_iova_to_phys() wrapper converts PHYS_ADDR_MAX -> 0 to
    maintain historical semantic for existing callers
  - generic_pt: use pt_entry_oa_lg2sz() which already handles
    contiguous PTE hints natively (Jason)
  - All drivers updated to return PHYS_ADDR_MAX for error/fault paths
    instead of 0

Guanghui Feng (30):
  iommu: introduce iova_to_phys_length in iommu_domain_ops
  iommu/io-pgtable-arm: introduce iova_to_phys_length in io_pgtable_ops
  iommu/io-pgtable-arm-v7s: introduce iova_to_phys_length in
    io_pgtable_ops
  iommu/io-pgtable-dart: introduce iova_to_phys_length in io_pgtable_ops
  iommu/generic_pt: implement iova_to_phys_length
  iommu/arm-smmu-v3: implement iova_to_phys_length
  iommu/arm-smmu: implement iova_to_phys_length
  iommu/qcom_iommu: implement iova_to_phys_length
  iommu/apple-dart: implement iova_to_phys_length
  iommu/ipmmu-vmsa: implement iova_to_phys_length
  iommu/mtk_iommu: implement iova_to_phys_length
  iommu/exynos: implement iova_to_phys_length
  iommu/fsl_pamu: implement iova_to_phys_length
  iommu/msm: implement iova_to_phys_length
  iommu/mtk_v1: implement iova_to_phys_length
  iommu/omap: implement iova_to_phys_length
  iommu/rockchip: implement iova_to_phys_length
  iommu/s390: implement iova_to_phys_length
  iommu/sprd: implement iova_to_phys_length
  iommu/sun50i: implement iova_to_phys_length
  iommu/tegra-smmu: implement iova_to_phys_length
  iommu/virtio: implement iova_to_phys_length
  vfio/iommufd: use iova_to_phys_length for efficient unmap
  drm/panfrost: switch to iova_to_phys_length
  drm/panthor: switch to iova_to_phys_length
  iommu/io-pgtable: selftests switch to iova_to_phys_length
  iommu/io-pgtable-arm: remove deprecated iova_to_phys wrapper
  iommu/io-pgtable-arm-v7s: remove deprecated iova_to_phys wrapper
  iommu/io-pgtable-dart: remove deprecated iova_to_phys wrapper
  iommu: remove iova_to_phys from domain_ops and io_pgtable_ops

 drivers/gpu/drm/panfrost/panfrost_mmu.c       |  2 +-
 drivers/gpu/drm/panthor/panthor_mmu.c         |  2 +-
 drivers/iommu/apple-dart.c                    | 13 ++--
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c   | 12 ++-
 .../iommu/arm/arm-smmu/arm-smmu-qcom-debug.c  |  2 +-
 drivers/iommu/arm/arm-smmu/arm-smmu.c         | 15 ++--
 drivers/iommu/arm/arm-smmu/qcom_iommu.c       | 13 ++--
 drivers/iommu/exynos-iommu.c                  | 23 ++++--
 drivers/iommu/fsl_pamu_domain.c               | 28 ++++++-
 drivers/iommu/generic_pt/iommu_pt.h           | 57 ++++++++------
 drivers/iommu/io-pgtable-arm-selftests.c      | 12 +--
 drivers/iommu/io-pgtable-arm-v7s.c            | 27 ++++---
 drivers/iommu/io-pgtable-arm.c                | 16 ++--
 drivers/iommu/io-pgtable-dart.c               | 21 ++++--
 drivers/iommu/iommu.c                         | 32 +++++++-
 drivers/iommu/iommufd/pages.c                 | 75 ++++++++++++++++---
 drivers/iommu/iommufd/selftest.c              |  2 +-
 drivers/iommu/ipmmu-vmsa.c                    | 12 ++-
 drivers/iommu/msm_iommu.c                     | 29 +++++--
 drivers/iommu/mtk_iommu.c                     | 14 +++-
 drivers/iommu/mtk_iommu_v1.c                  | 16 +++-
 drivers/iommu/omap-iommu.c                    | 34 ++++++---
 drivers/iommu/rockchip-iommu.c                | 13 +++-
 drivers/iommu/s390-iommu.c                    | 21 ++++--
 drivers/iommu/sprd-iommu.c                    | 20 +++--
 drivers/iommu/sun50i-iommu.c                  | 17 +++--
 drivers/iommu/tegra-smmu.c                    | 14 +++-
 drivers/iommu/virtio-iommu.c                  | 15 +++-
 drivers/vfio/vfio_iommu_type1.c               | 26 +++++--
 include/linux/generic_pt/iommu.h              | 13 ++--
 include/linux/io-pgtable.h                    | 10 ++-
 include/linux/iommu.h                         | 12 ++-
 32 files changed, 443 insertions(+), 175 deletions(-)

-- 
2.43.7