On Mon, Mar 27, 2023 at 03:37:54PM -0300, Jason Gunthorpe wrote: > This is the basic functionality for iommufd to support > iommufd_device_replace() and IOMMU_HWPT_ALLOC for physical devices. > > iommufd_device_replace() allows changing the HWPT associated with the > device to a new IOAS or HWPT. Replace does this in way that failure leaves > things unchanged, and utilizes the iommu iommu_group_replace_domain() API > to allow the iommu driver to perform an optional non-disruptive change. > > IOMMU_HWPT_ALLOC allows HWPTs to be explicitly allocated by the user and > used by attach or replace. At this point it isn't very useful since the > HWPT is the same as the automatically managed HWPT from the IOAS. However > a following series will allow userspace to customize the created HWPT. > > The implementation is complicated because we have to introduce some > per-iommu_group memory in iommufd and redo how we think about multi-device > groups to be more explicit. This solves all the locking problems in the > prior attempts. > > This series is infrastructure work for the following series which: > - Add replace for attach > - Expose replace through VFIO APIs > - Implement driver parameters for HWPT creation (nesting) > > Once review of this is complete I will keep it on a side branch and > accumulate the following series when they are ready so we can have a > stable base and make more incremental progress. When we have all the parts > together to get a full implementation it can go to Linus. I think this is reviewed now, so I've put it on a side branch "wip/for-nesting" until we get enough to have the replace series Thanks, Jason
