IOMMU 页表惰性回收 · v1

Introduce struct xarray reclaim_list to struct iommu_domain. This will serve as the O(1) storage where the fast path stores empty directories by their associated IOVA. IOVA is required by the shrinker

Implement a lockless state machine using the ioptdesc’s __page_refcount field. During an unmap, the driver executes atomic_sub_return() when clearing a leaf PTE. If the refcount drops to the baseline

Introduce a new sever_branch pt_iommu_op. This helper performs a top-down walk to locate the target parent slot and safely executes a lockless cmpxchg to 0x0. Because generic_pt abstracts all hardware

Under system memory pressure, intermediate IOMMU page table directories that were left stranded by sparse unmaps consume valuable RAM. Introduce an IO Page Table Shrinker to reclaim such memory. The

Update the count op to return real nr_pages that can be reclaimed. Signed-off-by: Pranjal Shrivastava praan@google.com — drivers/iommu/generic_pt/iommu_pt.h | 1 + drivers/iommu/generic_pt/shrin