RE: [PATCH v5 08/15] iommupt: Add read_and_clear_dirty op

From: Jason Gunthorpe jgg@nvidia.com Sent: Thursday, September 4, 2025 1:47 AM

IOMMU HW now supports updating a dirty bit in an entry when a DMA writes to the entry's VA range. iommufd has a uAPI to read and clear the dirty bits from the tables.

This is a trivial recursive descent algorithm to read and optionally clear the dirty bits. The format needs a function to tell if a contiguous entry is dirty, and a function to clear a contiguous entry back to clean.

Tested-by: Alejandro Jimenez alejandro.j.jimenez@oracle.com Signed-off-by: Jason Gunthorpe jgg@nvidia.com

Reviewed-by: Kevin Tian kevin.tian@intel.com