On Thu, May 19, 2022 at 02:03:48PM -0300, Jason Gunthorpe via iommu wrote: > Since asserting dma ownership now causes the group to have its DMA blocked > the iommu layer requires a working iommu. This means the dma_owner APIs > cannot be used on the fake groups that VFIO creates. Test for this and > avoid calling them. > > Otherwise asserting dma ownership will fail for VFIO mdev devices as a > BLOCKING iommu_domain cannot be allocated due to the NULL iommu ops. Fake iommu groups come back to bite again, part 42.. The patch looks good: Reviewed-by: Christoph Hellwig <hch@xxxxxx>