D4.1 About the Virtual Memory System Architecture (VMSA)
This chapter describes the Virtual Memory System Architecture (VMSA) that applies to a PE executing in AArch64 state. This is VMSAv8-64, as defined in ARMv8 VMSA naming on page D4-1643.
A VMSA provides a Memory Management Unit (MMU), that controls address translation, access permissions, and memory attribute determination and checking, for memory accesses made by the PE.
The process of address translation maps the virtual addresses (VAs) used by PE onto the physical addresses (PAs) of the physical memory system. These translations are defined independently for different Exception levels and Security states, and Figure D4-1 shows.
VMSAv8-64 supports tagging of VAs, as described in Address tagging in AArch64 state. As that section describes, this address tagging has no effect on the address translation process.
The remainder of this chapter gives a full description of VMSAv8-64 for an implementation that includes all of the Exception levels. The implemented Exception levels and the resulting translation stages and regimes on page D4-1679 describes the differences in the VMSA if some Exception levels are not implemented.