> From: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx> > Sent: Thursday, May 13, 2021 2:01 PM > > > > But this definitely all becomes HW specific. > > > > For instance I want to have an ARM vIOMMU driver it needs to do some > > > > ret = ioctl(ioasid_fd, CREATE_NESTED_IOASID, [page table format is > ARMvXXX]) > > if (ret == -EOPNOTSUPP) > > ret = ioctl(ioasid_fd, CREATE_NORMAL_IOASID, ..) > > // and do completely different and more expensive emulation > > > > I can get a little bit of generality, but at the end of the day the > > IOMMU must create a specific HW layout of the nested page table, if it > > can't, it can't. > > Erm.. I don't really know how your IOASID interface works here. I'm > thinking about the VFIO interface where maps and unmaps are via > explicit ioctl()s, which provides an obvious point to do translation > between page table formats. > We are working on a draft uAPI proposal based on the discussions in this thread. expect to send it out next week. Thanks Kevin
