Re: [PATCH] iommu/vt-d: Implement dma_[un]map_resource()

[Logan Gunthorpe]

On 2019-01-19 2:40 a.m., Christoph Hellwig wrote:
> Which resources do you plan to map?  At least for PCIe P2P adding
> an address translation seems wrong to me.

It's mapping a PCI BAR but not for PCIe P2P. In this case, we are using
the Intel I/OAT DMA engine to copy data from a PCI BAR to/from memory. See:

http://lkml.kernel.org/r/20190119001001.13087-1-logang@xxxxxxxxxxxx

>>
>> The implementation for intel_map_resource() is nearly identical to
>> intel_map_page(), we just have to re-create __intel_map_single().
>> dma_unmap_resource() uses intel_unmap_page() directly as the
>> functions are identical.
> 
> Instead of having two tiny wrappers I'd just revert
> 964f2311a6862f1fbcc044d0828ad90030928b7f if we need to pass a real
> physical address now.

Ok, I can resubmit this with that cleanup. Should I do it in two commits
(1 revert + 1 new) or is one commit that just restores the original
helper fine?

Thanks,

Logan