Hi, On Wed, Mar 16, 2022 at 02:49:09PM +0000, Robin Murphy wrote: > > What we want is to make sure the Tunneled PCIe ports get the full IOMMU > > protection. In case of the discrete above it is also fine if all the > > devices behind the PCIe root port get the full IOMMU protection. Note in > > the integrated all the devices are "siblings". > > Ah, OK, I wasn't aware that the NHI isn't even the right thing in the first > place :( > > Is there an easy way to get from the struct tb to a PCI device representing > the end of its relevant tunnel, or do we have a circular dependency problem > where the latter won't appear until we've authorised it (and thus the IOMMU > layer won't know about it yet either)? The PCIe root ports (and the PCIe downstream ports) are there already even without "authorization". There is a way to figure out the "tunneled" PCIe ports by looking at certain properties and we do that already actually. The BIOS has the following under these ports: https://docs.microsoft.com/en-us/windows-hardware/drivers/pci/dsd-for-pcie-root-ports#identifying-externally-exposed-pcie-root-ports and the ports will have dev->external_facing set to 1. Perhaps looking at that field helps here?
