> From: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Sent: Thursday, November 24, 2022 9:21 PM > > On Thu, Nov 24 2022 at 09:14, Jason Gunthorpe wrote: > > On Thu, Nov 24, 2022 at 10:37:53AM +0100, Thomas Gleixner wrote: > >> Jason said, that the envisioned Mellanox use case does not depend on the > >> IOMMU because the card itself has one which takes care of the > >> protections. > > > > Right, but that doesn't mean we need the physical iommu turned > > off. Setting the mlx pci device to identity mode is usually enough to > > get back to full performance. > > Ok. yes. IR can be enabled orthogonal to DMA mapping mode in IOMMU. > > >> How are we going to resolve that dilemma? > > > > The outcome is we don't have a strategy right now to make IMS work in > > VMs. This series is all about making it work on physical machines, > > that has to be a good first step. yes, that is the point. As long as IMS is disabled in the guest it's already a good first step for the moment. > > > > I'm hoping the OCP work stream on SIOV will tackle how to fix the > > interrupt problems. Some of the ideas I've seen could be formed into > > something that would work in a VM. > > Fair enough. > > Let me put the limitation into effect then. > > Thanks, > > tglx
