Il 27/09/2012 12:08, Avi Kivity ha scritto: >>>>> virtio-net is per-spec not going through the iommu. >>> >> What's that smell? A feature bit? >> > >> > Why is it a bad thing that it does not go through the iommu? > You can't assign the device to nested guests or to guest userspace via > vfio. Some guests may want to use the iommu even in the guest kernel > context.
All good points. However, using the iommu means you cannot use either vhost-net or (at least for now) per-device lock. So it closes some doors on performance improvements... I can imagine pSeries guys prefer to keep no iommu in virtio devices. Paolo
