On Wed, Sep 07, 2022 at 05:31:14PM +0100, Robin Murphy wrote: > The only trouble is that it's not geared for *PCI* P2P when that may or may > not happen entirely upstream of IOMMU translation. This is why PCI users have to call the pci_distance stuff before using dma_map_resource(), it ensures the PCI fabric is setup in a way that is consistent with the iommu. eg if we have IOMMU turned on then the fabric must have ACS/etc to ensure that all TLPs are translated. PCI P2P is very complicated and fragile, sadly. Thanks, Jason
