On Fri, Jul 01, 2022 at 11:40:26PM +0000, Tian, Kevin wrote: > But a bigger problem to me is how dma ownership is managed now on > POWER. Previously it was guarded by BUG_ON and vfio_group_viable(). Yes. Simply removing or deferring this can't be good. I think the solution is to not do iommu operations if there are no iommu_ops, including allocating a blocking domain or trying to change the domain - but continue to do all the refcounting/etc. It is just another crufty work around for platforms that don't support the iommu framework.. Jason
