[PATCH 0/4] arm64: IOMMU-backed DMA mapping

Robin Murphy robin.murphy at arm.com
Wed May 27 07:09:14 PDT 2015

Hi all,

Here's the cleaned-up and nominally ready-to-go IOMMU DMA mapping series,
with (I think) all the outstanding comments[1] addressed. I appreciate
I've probably missed the boat for 4.2, but I'm ever the optimist...

Major changes since RFC:
- Renamed things, shuffled things around, and removed some of the less
  useful abstraction for simplicity and clarity.
- Fixed iommu_dma_alloc to handle compound pages and map buffers as
- Filled the API holes like size-aligned allocations and get_sgtable.
- Solved the problem of attching devices to domains before the devices
  are created, which confuses IOMMU drivers like the ARM SMMU.

A branch is available at:
   git://linux-arm.org/linux-rm iommu/dma

In terms of where we go from here, this is more or less what I envisage:
- Get the current functionality merged to unblock arm64 IOMMU work
- Implement proper managed IOMMU domains around this, integrating the
  iova_domain into the iommu_domain itself, and getting rid of the
  iommu_dma_domain wrapper.
- Find all of the ad-hoc "managed domain" implementations in drivers
  currently using the arm_iommu_* functions and convert them to "proper"
  managed domains.
- Finally, with the external users taken care of, bring arch/arm over
  to the common DMA mapping code.

In the meantime, Laurent's proposal for probe deferral[2] offers hope
that the bus notifier dance may only need to be short-lived, and I'm
hoping to spend some more time on DT-based IOMMU group handling for
platform devices, which should hopefully tie in with default domains
to make the add_device callback mostly redundant.


Robin Murphy (4):
  iommu/iova: Avoid over-allocating when size-aligned
  iommu: Implement common IOMMU ops for DMA mapping
  arm64: Add IOMMU dma_ops
  arm64: Hook up IOMMU dma_ops

 arch/arm64/Kconfig                   |   1 +
 arch/arm64/include/asm/device.h      |   3 +
 arch/arm64/include/asm/dma-mapping.h |  25 +-
 arch/arm64/mm/dma-mapping.c          | 357 ++++++++++++++++++++++
 drivers/iommu/Kconfig                |   7 +
 drivers/iommu/Makefile               |   1 +
 drivers/iommu/dma-iommu.c            | 560 +++++++++++++++++++++++++++++++++++
 drivers/iommu/intel-iommu.c          |   2 +
 drivers/iommu/iova.c                 |  23 +-
 include/linux/dma-iommu.h            |  94 ++++++
 10 files changed, 1051 insertions(+), 22 deletions(-)
 create mode 100644 drivers/iommu/dma-iommu.c
 create mode 100644 include/linux/dma-iommu.h


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