On Mon, 13 May 2024 20:46:08 -0500, Gaurav Batra wrote:

Dynamic DMA Window (DDW) supports TCEs that are backed by 2MB page size.
In most configurations, DDW is big enough to pre-map all of LPAR memory
for IO. Pre-mapping of memory for DMA results in improvements in IO
performance.

Persistent memory, vPMEM, can be assigned to an LPAR as well. vPMEM is not
contiguous with LPAR memory and usually is assigned at high memory
addresses.  This makes is not possible to pre-map both vPMEM and LPAR
memory in the same DDW.

[...]

Applied to powerpc/next.

[1/1] powerpc/pseries/iommu: Split Dynamic DMA Window to be used in Hybrid mode
      https://git.kernel.org/powerpc/c/ff5163bb7000a0254ffdd7b50cb6df43add94f33

cheers