Re: [PATCH v3 0/2] Let iommupt manage changes in page size internally

[Baolu Lu <baolu.lu@linux.intel.com>]

On 2/28/26 03:30, Jason Gunthorpe wrote:
> Currently the core code has some helpers that use iommu_pgsize() to
> fragment operations into single page-size chunks and then the driver has a
> simplified single-page size implementation. This was helpful in
> simplifying the driver code.
> 
> However, iommupt has a single shared implementation for all formats so we
> can accept a little more complexity. Have the core code directly call
> iommupt with the requested range to map/unmap and rely on it to change the
> page size across the range as required.
> 
> The iommupt implementation of unmap is already fine to work like this, and
> the map implementation can reset its walking paramters in-place with a
> little more code.
> 
> The net result is about a 5% performance bump in the simple iommupt
> map/unmap benchmarks of mapped alignment, and probably more for
> unaligned/oddly sized ranges that are changing page sizes.
> 
> Introduce a iommupt_from_domain() function as a general way to convert
> an iommu_domain to a struct pt_iommu if it is a iommupt based domain. I
> expect to keep using this as more optimizations are introduced.
> 
> v3:
>   - Rebase to v7.0-rc1
> v2:https://patch.msgid.link/r/0-v2-973a6bdc820f+693- 
> iommpt_map_direct_jgg@nvidia.com
>   - Rebase to latest iommu tree
>   - Adjust to the IOMMU_DEBUG_PAGEALLOC work
>   - Fix missed trace calls for both map and unmap
>   - Add a comment explaining the level changes
> v1:https://patch.msgid.link/r/0-v1-d7be57da596d+3f8c0- 
> iommpt_map_direct_jgg@nvidia.com
> 
> Jason Gunthorpe (2):
>    iommupt: Directly call iommupt's unmap_range()
>    iommupt: Avoid rewalking during map
> 
>   drivers/iommu/generic_pt/iommu_pt.h         | 162 +++++++++++---------
>   drivers/iommu/generic_pt/kunit_generic_pt.h |  12 ++
>   drivers/iommu/generic_pt/pt_iter.h          |  22 +++
>   drivers/iommu/iommu.c                       |  66 ++++++--
>   include/linux/generic_pt/iommu.h            |  69 +++++++--
>   include/linux/iommu.h                       |   1 +
>   6 files changed, 231 insertions(+), 101 deletions(-)

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>