VIRTUALISATION SUPPORTING GUEST OPERATING SYSTEMS USING MEMORY PROTECTION UNITS

摘要

A processor (20) is provided with a first memory protection unit (38) applying a first set of permissions and a second memory protection unit (40) applying a second set of permissions. A memory access will only be permitted if both the first set of permissions and the second set of permissions are satisfied. The processor also includes a memory management unit (42) which serves to translate from virtual addresses VA to physical addresses PA. A selectable one of the first memory protection unit (38) and the memory management unit (42) is active at any given time under control of a selection bit set by a hypervisor program (2) executing at an exception level with higher privilege than the exception level at which the guest operating systems execute.

主权项

1. Apparatus for processing data comprising:
processing circuitry configured to execute a stream of program instructions; a first memory protection unit configured:
to receive a physical address directly specifying a memory address location within a memory for a memory access operation to be performed by said processing circuitry; andto determine in accordance with a first set of permissions whether or not said memory access operation is permitted; and a second memory protection unit configured:
to receive said physical address; andto determine in accordance with a second set of permissions whether or not said memory access operation is permitted; whereby said memory access operation is permitted only if it satisfies both said first set of permissions and said second set of permissions.