> From: Tian, Kevin > Sent: Friday, March 2, 2018 2:54 PM > > > From: Alex Williamson > > Sent: Friday, March 2, 2018 4:22 AM > > > > > > I am pretty sure that you are describing is true of some, but not for > > > all. I think the Amazon solutions and the virtio solution are doing > > > hard partitioning of the part. I will leave it to those guys to speak > > > for themselves since I don't know anything about the hardware design > > > of those parts. > > > > I think we'd need device specific knowledge and enablement to be able > > to take advantage of any hardware partitioning, otherwise we need to > > assume the pf is privileged, as implemented in other sriov devices. > > > > I'm also trying to imagine whether there's a solution via the new > > vfio/mdev interface, where the mdev vendor driver would bind to the pf > > and effectively present itself as the mdev device. The vendor driver > > could provide sriov capabilities and bear the burden of ensuring that > > the pf is used cooperatively. The only existing mdev vendor drivers are > > vGPUs and rely on on-device DMA translation and isolation, such as > > through GTTs, but there have been some thoughts on providing IOMMU > > based > > isolation of mdev/sriov mixed devices (assuming DMA is even required > > for userspace management of the pf in this use case). [Cc Kirti] > > Thanks, > > > > Hope not distracting this thread, but above sounds like an interesting > idea. Actually we ever brainstormed similar thought for another > potential usage - supporting VF live migration. We are already working > on an generic extension to allow state save/restore of mdev instance. > If vendor driver could further wrap pf as a mdev instance, it could I meant "wrap vf as a mdev instance" here. > leverage the same framework for a clean state migration on VF. based > on mmap callback the vendor driver can easily switch back-and-forth > between pass through and trap/emulation of the VF resources. Of > course doing so alone doesn't address all the demands of VF live > migration (e.g. dirty page tracking still requires other techniques), > but it does pave a way toward a general framework to support VF > live migration. > > If above is feasible, finally we could use one mdev framework to > manage both mdev and pf/vf assignment, while providing added > values which are difficult to achieve today. :-) > > Thanks > Kevin
