On Mon, 6 Mar 2023 11:30:20 -0600 (CST), Timothy Pearson wrote:

PPC64 IOMMU API defines iommu_table_group_ops which handles DMA windows
for PEs: control the ownership, create/set/unset a table the hardware
for dynamic DMA windows (DDW). VFIO uses the API to implement support
on POWER.

So far only PowerNV IODA2 (POWER8 and newer machines) implemented this and other cases (POWER7 or nested KVM) did not and instead reused
existing iommu_table structs. This means 1) no DDW 2) ownership transfer
is done directly in the VFIO SPAPR TCE driver.

[...]

Applied to powerpc/next.

[1/4] powerpc/iommu: Add "borrowing" iommu_table_group_ops
      https://git.kernel.org/powerpc/c/9d67c94335096311c0bc7556ad1022de7385790b

cheers