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So, at the moment, this just looks like a burden to me, especially > as it appears to create a brand new, device-specific UAPI for what is > ostensibly a form of SVA - something which the community is actively > working on already. Yeah, I think it was a mistake to hardwire the invalidation to the CPU. It would fit much better into Linux if the invalidation was separate and independently controllable with an option to follow the CPU. Then you could use a normal S2 page table through iommufd and not mess with kvm. (though the VMID sharing with KVM for a BTM-like scheme was never solved upstream) I also wouldn't expect you to use vfio-mdev, if the devices are discovered and known at boot then it should be a normal vfio driver. Jason