On Mon, Feb 14, 2022 at 11:46:26AM -0400, Jason Gunthorpe wrote: > On Mon, Feb 14, 2022 at 03:18:31PM +0000, Robin Murphy wrote: > > > Arguably, iommu_attach_device() could be renamed something like > > iommu_attach_group_for_dev(), since that's effectively the semantic that all > > the existing API users want anyway (even VFIO at the high level - the group > > is the means for the user to assign their GPU/NIC/whatever device to their > > process, not the end in itself). That's just a lot more churn. > > Right Okay, good point. I can live with an iommu_attach_group_for_dev() interface, it is still better than making iommu_attach_device() silently operate on whole groups. > VFIO needs them because its uAPI is tied, but even so we keep talking > about ways to narrow the amount of group API it consumes. > > We should not set the recommended/good kAPI based on VFIOs uAPI > design. Agree here too. The current way groups are implemented can be turned into a VFIO specific interface to keep its semantics and kABI. But the IOMMU core code still needs the concept of alias groups. Regards, Joerg
