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They do not have an IOMMU and do not use a VFIO container. > The VMM needs device-specific knowledge in order to create a virtual > device (device tree, ACPI tables), so it also knows not to allocate a > container. I'm not so excited to see new things built on top of the group interface. Maybe in this case you just don't have to do a bind operation on the cdev to an iommufd? That feels kind of natural if you don't use a iommufd However.. you still have to affirm which single mm is the mm that the device is going to be doing DMA against. The process the opens the fd should not be forced to be the mm that it gets linked to. >From that perspective maybe you should create an iommufd and a special "SVA" IOAS that it can attach to. This is more complicated but it makes the mm linkage and blocking beahvior explicit and controlled by userspace. Jason