I may try it anyway.
One more thing:
adding aio=native causes this problem:
kvm: -drive file=/dev/zvol/rpool/data/vm-216-disk-0,if=none,id=drive-scsi0,cache=writeback,aio=native,format=raw,detect-zeroes=on: aio=native was specified, but it requires cache.direct=on, which was not specified...