Google states that just in case of hardware failure, your VM will be migrated if doable, or restarted on a brand new host if migration isn't doable.
Live migration keeps your instances running during:
Failed hardware like memory, CPU, network interface cards, disks, power, and so on.
This is done on a best-effort basis; if a hardware fails totally or otherwise prevents live migration, the VM crashes and restarts mechanically and a hostError is logged.