A processing unit, where the processing unit one of a group of processing units of a system, includes a processor; and memory including instructions, which when executed by the processor while avoiding interrupting a controller that does not belong to the group of processing units, cause the processor to: perform at least one iteration of the steps of: (a) entering a trusted mode, (b) selecting a selected job to be executed by the processing unit, (c) retrieving access control metadata related to the selected job, (d) entering, by the processing unit, an untrusted mode, (e) executing the selected job by the processing unit while adhering to the access control metadata related to the job, and (f) resetting the processing unit.