Re: [PATCH v4 07/18] PCI/P2PDMA: Document the Address Type assumption

Jason Gunthorpe <[email protected]>
Newsgroups org.kernel.vger.linux-doc,dev.linux.lists.iommu,org.kernel.vger.linux-kernel,org.kernel.vger.linux-pci
Message-ID <178761377055.3197084.12191528318950950293.b4-review@b4>
> [ ... 21 lines skipped ... ]
> +This evaluation covers the ACS controls that govern Requests carrying an
> +Untranslated address. Unless ACS Translation Blocking is enabled, a Port
> +with ACS Direct Translated P2P enabled routes a Request carrying a Translated
> +address directly to the peer regardless of those controls. An ATS capable
> +client may therefore reach the peer on the direct path whichever mapping the
> +kernel selects.

My note on the cover letter applies here.. A user of the p2p subsystem
kind of has to issue untranslated strict ordered TLPs otherwise the
ACS analysis is not correct.

A translated address routing to the host bridge for a peer device
still requires support in the host bridge to hairpin back out.

So I would prefer this is clarified to that that exactly, using it
with ATS translated TLPs is not defined.

-- 
Jason
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