Yes! I also started with using vm_memory traits in the beginning but delayed it till I refactor my memory subsystem. When we get that in upstream QEMU it might be possible to share this implementation as well as future devices.
Yep, vm-memory needs pretty large changes to the crate itself but fortunately they're already in progress to add IOMMU support to the virtio and vhost crates. Probably there will be an API break but with old and new crates able to talk to each other so you don't need a flag day.
I am curious if you get to DMA before or after QEMU, and if before what your API will look like.
