On Tue, 19 Jul 2016 07:06:34 +0000 "Tian, Kevin" <kevin.tian@xxxxxxxxx> wrote: > > From: Alex Williamson > > Sent: Tuesday, July 19, 2016 5:34 AM > > > > On Sun, 17 Jul 2016 13:05:21 +0300 > > Haggai Eran <haggaie@xxxxxxxxxxxx> wrote: > > > > > On 7/14/2016 8:03 PM, Alex Williamson wrote: > > > >> 2. Add an owner_pid to struct vfio_group and make sure in > > vfio_group_get_device_fd that > > > >> > the PFs vfio_group is owned by the same process as the one that is trying to get > > a fd for a VF. > > > > This only solves a very specific use case, it doesn't address any of > > > > the issues where the VF struct device in the host kernel might get > > > > bound to another driver. > > > The current patch uses driver_override to make the kernel use VFIO for > > > all the new VFs. It still allows the host kernel to bind them to another > > > driver, but that would require an explicit action on the part of the > > > administrator. Don't you think that is enough? > > > > Binding the VFs to vfio-pci with driver_override just prevents any sort > > of initial use by native host drivers, it doesn't in any way tie them to > > the user that created them or prevent any normal operations on the > > device. The entire concept of a user-created device is new and > > entirely separate from a user-owned device as typically used with > > vfio. We currently have an assumption with VF assignment that the PF > > is trusted in the host, that's broken here and I have a hard time > > blaming it on the admin or management tool for allowing such a thing > > when it previously hasn't been a possibility. If nothing else, it > > seems like we're opening the system for phishing attempts where a user > > of a PF creates VFs hoping they might be assigned to a victim VM, or > > worse the host. > > > > What about fully virtualizing the SR-IOV capability? The VM is not allowed > to touch physical SR-IOV capability directly so there would not be a problem > of user-created devices. Physical SR-IOV is always enabled by admin at > the host side. Admin can combine any number of VFs (even cross multiple > compatible devices) in the virtual SR-IOV capability on any passthrough > device... > > The limitation is that the VM can initially access only PF resource which is > usually less than what the entire device provides, so not that efficient > when the VM doesn't want to enable SR-IOV at all. Are you suggesting a scenario where we have one PF with SR-IOV disabled assigned to the user and another PF owned by the host with SR-IOV enable, we virtualize SR-IOV to the user and use the VFs from the other PF to act as a "pool" of VFs to be exposed to the user depending on SR-IOV manipulation? Something like that could work with existing vfio, just requiring the QEMU bits to virtualize SR-IOV and mange the VFs, but I expect it's not a useful model for Mellanox. I believe it was Ilya that stated the purpose in exposing SR-IOV was for development, so I'm assuming they actually want to do development of the PF SR-IOV enabling in a VM, not just give the illusion of SR-IOV to the VM. Thanks, Alex -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
