On Wed, Mar 04, 2026 at 03:57:57PM +0100, Danilo Krummrich wrote: > On Wed Mar 4, 2026 at 3:26 PM CET, Leon Romanovsky wrote: > > On Wed, Mar 04, 2026 at 10:18:52AM -0400, Jason Gunthorpe wrote: > >> On Wed, Mar 04, 2026 at 10:47:50AM +0200, Leon Romanovsky wrote: > >> > On Tue, Mar 03, 2026 at 04:15:20PM -0500, Peter Colberg wrote: > >> > > Add Rust abstractions for the Single Root I/O Virtualization (SR-IOV) > >> > > capability of a PCI device. Provide a minimal set of wrappers for the > >> > > SR-IOV C API to enable and disable SR-IOV for a device, and query if > >> > > a PCI device is a Physical Function (PF) or Virtual Function (VF). > >> > > >> > <...> > >> > > >> > > For PF drivers written in C, disabling SR-IOV on remove() may be opted > >> > > into by setting the flag managed_sriov in the pci_driver structure. For > >> > > PF drivers written in Rust, disabling SR-IOV on unbind() is mandatory. > >> > > >> > Why? Could you explain the rationale behind this difference between C and > >> > Rust? Let me remind you that SR‑IOV devices which do not disable VFs do > >> > so > >> > for a practical and well‑established reason: maximizing hardware > >> > utilization. > >> > >> Personally I think drivers doing this are wrong. That such a driver > >> bug was allowed to become UAPI is pretty bad. The rust approach is > >> better. > > > > We already had this discussion. I see this as a perfectly valid > > use-case. > > Can you remind about a specific use-case for this please? (Ideally, one that > can't be solved otherwise.)
You create X VFs through sriov_configure, unbind PF, bind it to vfio instead and forward (X + 1) functions to different VMs. If you destroy VFs on PF unbind, you will find yourself with one function less per-device, as you will have not-utilized PF now, which consumes HW resources anyway. Thanks
