According to PCIe spec (7.8.9 PASID Extended Capability Structure): The PASID configuration of the single non-VF Function representing the device is also used by all VFs in the device. A PF is permitted to implement the PASID capability, but VFs must not implement it. To enable PASID on VF then one open is where to locate the PASID capability in VF's vconfig space. vfio-pci doesn't know which offset may contain VF specific config registers. Finding such offset must come from a device specific knowledge. iirc we haven't closed this open in previous discussion. It's probably right time to revisit it and agree on a solution now. Three options on the table: 1) Use vfio-pci variant driver. Easy to support especially when the VF also plans to support live migration. is it overburdened otherwise? 2) Have vfio-pci maintain a table tracking hard-coded offset per vendor/device ID. 3) Extend PCI core to allow PF driver specifying the offset for VF Which one is cleanest in your view? Thanks Kevin
