Masking of architectural state associated with a realm

摘要

Software processes at a plurality of exception levels (EL) have corresponding realms: owner realms, e.g. guest virtual machines VMs, can prevent access to associated regions to processes at more privileged ELs, e.g. the hypervisor. A realm can be associated to processes at different ELs, the most privileged defining the boundary exception level BEL. Exception conditions (430) cause realm exiting requiring handling at a target exception level higher than the boundary exception level (432). This triggers state masking for making inaccessible the architectural state of a subset of registers to processes having ELs higher than BEL (442, 443). The subset of registers is selected depending on the boundary exception level, where each EL is associated to a group of registers accessible when processing software at that EL. The masked states are immediately or lazily saved to a realm execution context memory region associated to the realm where the exception occurred (444). State masking comprises scrubbing.