well. ok. specifics... i have 3 netbsd instances on aws. one is mostly testing and fortunately that was the one targeted first for reboot "because of scheduled maintenance". after the reboot this happens:
============= Init TPM Front ================
Tpmfront:Error Unable to read device/vtpm/0/backend-id during tpmfront initialization! error = ENOENT
Tpmfront:Info Shutting down tpmfront
close blk: backend=/local/domain/0/backend/vbd/1784/2049 node=device/vbd/2049
=============================
this also happens if i try starting a new instance with any of the official netbsd 6 and 7 images.
if the assumption that the rebooted instance is moved to a kvm host is correct, then, yes the current official images are not working. or any of the "community" ones for that matter. it's also worth noting that it seems that the official netbsd aws builds page has not been updated for about 2 years.