Re: [vfio-users] SR-IOV PF Passthrough
Hi Alex, Thanks for the explanation! What a pity but I will workaround by manually assigning VFs. The emulation based approach is also interesting but seems requiring much efforts. I'm happy to see it (eventually) being implemented someday. Thanks, Tydus On 2022/6/4 0:51, Alex Williamson wrote: On Fri, 3 Jun 2022 23:13:39 +0900 Tydus wrote: Hi list, I'm trying to passthrough an SR-IOV capable device (PF) into a VM and make it spawn VFs into it and had no luck. Digging into qemu vfio code I found https://github.com/qemu/qemu/commit/e37dac06dc4e85a2f46c24261c0dfdf2a30b50e3 which gives me some insights about the situation at that time. However I wonder if this situation had changed since. It seems vIOMMU has been implemented and VFIO adds SR-IOV support these years (but it might be not related). Sorry if I'm wrong but I'm not that familiar with VFIO and PCIE internals. Any help or information is appreciated. Hi Tydus, It's a common misconception that a VM owned PF can enable SR-IOV and the VFs will simply appear in the VM. This is not how PCI device assignment works. The PF is virtualized into the VM and VF devices created by the PF must also be created on the host and virtalized into the VM. The kernel vfio-pci driver has support for enabling SR-IOV, but the QEMU and above stack does not. Effectively a VM interaction with the PF SR-IOV capability would need to be trapped and signaled to a management tool like libvirt to perform the SR-IOV configuration in the host, after which the new host VFs would be collected and attached to the VM to emulate the bare metal process. All of this latter process is currently unimplemented. Thanks, Alex ___ vfio-users mailing list vfio-users@redhat.com https://listman.redhat.com/mailman/listinfo/vfio-users
Re: [vfio-users] SR-IOV PF Passthrough
On Fri, 3 Jun 2022 23:13:39 +0900 Tydus wrote: > Hi list, > > I'm trying to passthrough an SR-IOV capable device (PF) into a VM and > make it spawn VFs into it and had no luck. > > Digging into qemu vfio code I found > https://github.com/qemu/qemu/commit/e37dac06dc4e85a2f46c24261c0dfdf2a30b50e3 > which gives me some insights about the situation at that time. However I > wonder if this situation had changed since. It seems vIOMMU has been > implemented and VFIO adds SR-IOV support these years (but it might be > not related). > > Sorry if I'm wrong but I'm not that familiar with VFIO and PCIE > internals. Any help or information is appreciated. Hi Tydus, It's a common misconception that a VM owned PF can enable SR-IOV and the VFs will simply appear in the VM. This is not how PCI device assignment works. The PF is virtualized into the VM and VF devices created by the PF must also be created on the host and virtalized into the VM. The kernel vfio-pci driver has support for enabling SR-IOV, but the QEMU and above stack does not. Effectively a VM interaction with the PF SR-IOV capability would need to be trapped and signaled to a management tool like libvirt to perform the SR-IOV configuration in the host, after which the new host VFs would be collected and attached to the VM to emulate the bare metal process. All of this latter process is currently unimplemented. Thanks, Alex ___ vfio-users mailing list vfio-users@redhat.com https://listman.redhat.com/mailman/listinfo/vfio-users
[vfio-users] SR-IOV PF Passthrough
Hi list, I'm trying to passthrough an SR-IOV capable device (PF) into a VM and make it spawn VFs into it and had no luck. Digging into qemu vfio code I found https://github.com/qemu/qemu/commit/e37dac06dc4e85a2f46c24261c0dfdf2a30b50e3 which gives me some insights about the situation at that time. However I wonder if this situation had changed since. It seems vIOMMU has been implemented and VFIO adds SR-IOV support these years (but it might be not related). Sorry if I'm wrong but I'm not that familiar with VFIO and PCIE internals. Any help or information is appreciated. Regards, Tydus ___ vfio-users mailing list vfio-users@redhat.com https://listman.redhat.com/mailman/listinfo/vfio-users
