Re: [PATCH 0/7] Use the generic iommu page table for SMMUv3

[Mostafa Saleh <smostafa@google.com>]

On Mon, Jul 06, 2026 at 01:29:06PM -0300, Jason Gunthorpe wrote:
> [ This is the last patch to move SMMUv3 over to the generic page
>   table:
> 1) Organize the SMMUv3 invalidation flow so iommupt can use it
>   ..
> 2) Use the generic iommu page table for SMMUv3
> 
> It depends on #1
> 
> The whole branch is here:
>    https://github.com/jgunthorpe/linux/commits/iommu_pt_arm64/
> ]
> 
> Introduce the generic page table for what the ARM spec calls VMSAv8-64
> (ie the long 64 bit PTE page table, io-pgtable-arm.c) and use it for
> SMMUv3. ARM is by far the most complex page table of all the ones
> implemented, it has the most runtime behavior variations and a lot of
> features.
> 
> Like the othe architectures, the page table itself is supported by a kunit
> compare test that runs operations through both io-pgtable-arm.c and the
> new code then checks for identical PTEs. This is on the github link above
> but I don't intend to merge it.
> 
> The existing kunit tests for iommupt will automatically cover the new
> format as well.
> 
> This is the final series migrating the SMMUv3 driver over to use the new
> functions and remove io-pgtable-arm.c usage. In principle the other iommu
> drivers that use io-pgtable-arm could be converted someday as well.
> 
> Robin once mentioned there were errata about contiguous bits, I only found
> 3673557 and it is mitigated in this design by always using RIL. I'm
> assuming that RIL is always available in SMMUs that are effected by
> 3673557? I have a patch add a FEAT if for contiguous bits if that is
> required.
> 
> Jason Gunthorpe (7):
>   iommupt: Remove the sanity check for pt_num_items_lg2() at the top
>     level
>   iommupt/kunit: Skip test configs without supported features
>   iommupt: Add the 64 bit ARMv8 page table format
>   iommu/arm-smmu-v3: Remove io-pgtable-arm from sva.c
>   iommu/arm-smmu-v3: Move the DMA API comment to flush_iotlb_all
>   iommu/arm-smmu-v3: Use the generic iommu page table
>   iommu: Remove pgsize from iommu_iotlb_gather

I went through the series, it seems the arm work plug in nicely with
the iommupt stuff, I left some comments around, but I feel that
patches 1,2 and 5 can be sent separately.

And patch 8 it too large to review, it would be better to split into
3-6 patches, I was thinking: base support, dirty tracking, contig bit
aarch32 and kunit.

Thanks,
Mostafa

> 
>  drivers/iommu/arm/Kconfig                     |    4 +-
>  .../iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c   |   13 +-
>  .../iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c  |   45 +-
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c   |  287 ++---
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h   |   18 +-
>  drivers/iommu/generic_pt/.kunitconfig         |    1 +
>  drivers/iommu/generic_pt/Kconfig              |   12 +
>  drivers/iommu/generic_pt/fmt/Makefile         |    2 +
>  drivers/iommu/generic_pt/fmt/armv8.h          | 1124 +++++++++++++++++
>  drivers/iommu/generic_pt/fmt/defs_armv8.h     |   23 +
>  drivers/iommu/generic_pt/fmt/iommu_armv8.c    |   13 +
>  drivers/iommu/generic_pt/iommu_pt.h           |   14 -
>  drivers/iommu/generic_pt/kunit_iommu.h        |   10 +
>  include/linux/generic_pt/common.h             |   42 +
>  include/linux/generic_pt/iommu.h              |   73 ++
>  include/linux/iommu.h                         |   62 +-
>  16 files changed, 1452 insertions(+), 291 deletions(-)
>  create mode 100644 drivers/iommu/generic_pt/fmt/armv8.h
>  create mode 100644 drivers/iommu/generic_pt/fmt/defs_armv8.h
>  create mode 100644 drivers/iommu/generic_pt/fmt/iommu_armv8.c
> 
> 
> base-commit: 8cd13c14dcc29762766ff9ca2f67e3bae7c7cb77
> -- 
> 2.43.0
>