Hi, to make progress on this, we should first agree on the protocol used between guest and host. I have a few points to discuss on the protocol first. On Tue, Dec 11, 2018 at 06:20:57PM +0000, Jean-Philippe Brucker wrote: > [1] Virtio-iommu specification v0.9, sources and pdf > git://linux-arm.org/virtio-iommu.git virtio-iommu/v0.9 > http://jpbrucker.net/virtio-iommu/spec/v0.9/virtio-iommu-v0.9.pdf Looking at this I wonder why it doesn't make the IOTLB visible to the guest. the UNMAP requests seem to require that the TLB is already flushed to make the unmap visible. I think that will cost significant performance for both, vfio and dma-iommu use-cases which both do (vfio at least to some degree), deferred flushing. I also wonder whether the protocol should implement a protocol version handshake and iommu-feature set queries. > [3] git://linux-arm.org/linux-jpb.git virtio-iommu/v0.9.1 > git://linux-arm.org/kvmtool-jpb.git virtio-iommu/v0.9 Unfortunatly gitweb seems to be broken on linux-arm.org. What is missing in this patch-set to make this work on x86? Regards, Joerg
