On Mon, Jan 18, 2021 at 05:00:09PM +0100, Cornelia Huck wrote: > > You can say that all the HW specific things are in the mlx5_vfio_pci > > driver. It is an unusual driver because it must bind to both the PCI > > VF with a pci_driver and to the mlx5_core PF using an > > auxiliary_driver. This is needed for the object lifetimes to be > > correct. > > Hm... I might be confused about the usage of the term 'driver' here. > IIUC, there are two drivers, one on the pci bus and one on the > auxiliary bus. Is the 'driver' you're talking about here more the > module you load (and not a driver in the driver core sense?) Here "driver" would be the common term meaning the code that realizes a subsytem for HW - so mlx5_vfio_pci is a VFIO driver because it ultimately creates a /dev/vfio* through the vfio subsystem. The same way we usually call something like mlx5_en an "ethernet driver" not just a "pci driver" > Yes, sure. But it also shows that mlx5_vfio_pci aka the device-specific > code is rather small in comparison to the common vfio-pci code. > Therefore my question whether it will gain more specific changes (that > cannot be covered via the auxiliary driver.) I'm not sure what you mean "via the auxiliary driver" - there is only one mlx5_vfio_pci, and the non-RFC version with all the migration code is fairly big. The pci_driver contributes a 'struct pci_device *' and the auxiliary_driver contributes a 'struct mlx5_core_dev *'. mlx5_vfio_pci fuses them together into a VFIO device. Depending on the VFIO callback, it may use an API from the pci_device or from the mlx5_core_dev device, or both. Jason
