Merge pull request #1198 from antonio-nino-diaz-arm/an/spm-doc

Add Secure Partition Manager (SPM) design document

docs/spm-user-guide.rst

-ARM Trusted Firmware - SPM User Guide
-=====================================
-
-.. section-numbering::
-    :suffix: .
-
-.. contents::
-
-
-This document briefly presents the Secure Partition Management (SPM) support in
-the Arm Trusted Firmware (TF), specifically focusing on how to build Arm TF with
-SPM support.
-
-Overview of the SPM software stack
-----------------------------------
-
-SPM is supported on the Arm FVP exclusively at the moment.
-
-It is not currently possible for BL31 to integrate SPM support and a Secure
-Payload Dispatcher (SPD) at the same time; they are mutually exclusive. In the
-SPM bootflow, a Secure Partition (SP) image executing at Secure-EL0 replaces the
-Secure Payload image executing at Secure-EL1 (e.g. a Trusted OS). Both are
-referred to as BL32.
-
-A working prototype of a SP has been implemented by repurposing the EDK2 code
-and tools, leveraging the concept of the *Standalone Management Mode (MM)* in
-the UEFI specification (see the PI v1.6 Volume 4: Management Mode Core
-Interface). This will be referred to as the *Standalone MM Secure Partition* in
-the rest of this document.
-
-
-Building TF with SPM support
-----------------------------
-
-To enable SPM support in the TF, the source code must be compiled with the build
-flag ``ENABLE_SPM=1``. On Arm platforms the build option ``ARM_BL31_IN_DRAM``
-can be used to select the location of BL31, both SRAM and DRAM are supported.
-
-
-Using the Standalone MM SP
-~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-First, build the Standalone MM Secure Partition. To build it, refer to the
-`instructions in the EDK2 repository`_.
-
-Then build TF with SPM support and include the Standalone MM Secure Partition
-image in the FIP:
-
-::
-
-    BL32=path/to/standalone/mm/sp BL33=path/to/bl33.bin \
-    make PLAT=fvp ENABLE_SPM=1 fip all
-
-
---------------
-
-*Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.*
-
-.. _instructions in the EDK2 repository: https://github.com/tianocore/edk2-staging/blob/AArch64StandaloneMm/HowtoBuild.MD