Re: [PATCH 0/4] PCI, iommu: Factor 'untrusted' check for ATS enablement

Will Deacon
2020-05-15T17:25:38Z

Hi,

On Fri, May 15, 2020 at 10:19:49AM -0700, Raj, Ashok wrote:
> On Fri, May 15, 2020 at 08:43:51AM -0700, Christoph Hellwig wrote:
> > Can you please lift the untrusted flag into struct device? It really
> > isn't a PCI specific concept, and we should not have code poking into
> > pci_dev all over the iommu code.
>
> Just for clarification: All IOMMU's today mostly pertain to only PCI devices
> and for devices that aren't PCI like HPET for instance we give a PCI
> identifier. Facilities like ATS for instance require the platform to have
> an IOMMU.
>
> what additional problems does moving this to struct device solve?

ATS is PCI specific, but IOMMUs certainly aren't! The vast majority of
IOMMUs deployed in arm/arm64 SoCs are /not/ using any sort of PCI.

Will