There are several additional challenges when a Microdroid pVM payload is delivered inside a Mainline module.
Mainline modules are expected to be rolled back on a device in case a problem with a Mainline release has been detected. This doesn't work well with the rollback protection of Microdroid pVMs - if a payload is updated, then a previous version of the payload is not allowed to access it's secrets.
To work around this challenge, payloads delivered via Mainline modules are expected to request android.permission.USE_RELAXED_MICRODROID_ROLLBACK_PROTECTION privileged permission.
TODO(ioffe): add more context on how permission is used once the implementation is done.