On Mon, Jan 8, 2018 at 11:57 AM, Christoph Hellwig [off-list ref] wrote:

quoted

(c) setup/manage any security permissions on mappings
Which P2P may at some point be concerned with.

Maybe once root complexes with iommus actually support P2P.  But until
then we have a lot more more important problems to solve.

Pretty sure P2P capable IOMMU hardware exists.

With SOC's we also have the scenario that an DMA originated from an
on-die device wishes to target an off-die PCI BAR (through the IOMMU),
that definitely exists today, and people care about it :)

Jason