On Mon, 2015-10-26 at 05:43 +0100, Joerg Roedel wrote:
> But it would actually be neat to have at least the option to translate
> virtio DMA through an emulated IOMMU to be able to pass a virtio-device
> to a nested guest.

It would be useful to have an emulated IOMMU, full stop. And yeah, it
might actually make sense to *start* by using it for purely virtual
devices, and then graduate to doing it for passthrough (which will
finally mean we can stop having to pin *all* guest memory the moment we
assign a device, and we only have to pin those pages which are
referenced from the IOMMU page tables).

-- 
dwmw2