Re: [PATCH 06/12] IB/core: Add optional PCI P2P flag to rdma_rw_ctx_[init|destroy]()

Jason Gunthorpe
2018-01-08T19:49:57Z

On Mon, Jan 8, 2018 at 11:57 AM, Christoph Hellwig <hch@lst.de> wrote:

>> (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