docs: add FFA_MSG_SEND_DIRECT_REQ2/RESP2 support

Add FFA_MSG_SEND_DIRECT_REQ2/RESP2 to list of supported
interfaces. Also update references to FFA_MSG_SEND_DIRECT_REQ
that also apply to FFA_MSG_SEND_DIRECT_REQ2.

Signed-off-by: Kathleen Capella <kathleen.capella@arm.com>
Change-Id: I72271019381a8eaff1a8ecdb4580f89e984f4d48
diff --git a/docs/secure-partition-manager/secure-partition-manager.rst b/docs/secure-partition-manager/secure-partition-manager.rst
index 317130c..3115f8e 100644
--- a/docs/secure-partition-manager/secure-partition-manager.rst
+++ b/docs/secure-partition-manager/secure-partition-manager.rst
@@ -598,7 +598,7 @@
 The FF-A specification `[1]`_ provides two ways to allocate CPU cycles to
 secure partitions. For this a VM (Hypervisor or OS kernel), or SP invokes one of:
 
-- the FFA_MSG_SEND_DIRECT_REQ interface.
+- the FFA_MSG_SEND_DIRECT_REQ (or FFA_MSG_SEND_DIRECT_REQ2) interface.
 - the FFA_RUN interface.
 
 Additionally a secure interrupt can pre-empt the normal world execution and give
@@ -647,7 +647,10 @@
  - ``FFA_RX_ACQUIRE``
 
 As part of the FF-A v1.2 support, the following interfaces were added:
+
 - ``FFA_PARTITION_INFO_GET_REGS``
+- ``FFA_MSG_SEND_DIRECT_REQ2``
+- ``FFA_MSG_SEND_DIRECT_RESP2``
 
 FFA_VERSION
 ~~~~~~~~~~~
@@ -768,6 +771,15 @@
 - An Hypervisor or OS kernel can send a direct request to an SP.
 - An SP can send a direct response to an Hypervisor or OS kernel.
 
+FFA_MSG_SEND_DIRECT_REQ2/FFA_MSG_SEND_DIRECT_RESP2
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The primary usage of these ABIs is to send a direct request to a specified
+UUID within an SP that has multiple UUIDs declared in its manifest.
+
+Secondarily, it can be used to send a direct request with an extended
+set of message payload arguments.
+
 FFA_NOTIFICATION_BITMAP_CREATE/FFA_NOTIFICATION_BITMAP_DESTROY
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
@@ -1143,7 +1155,8 @@
   - RTM_FFA_RUN: runtime model presented to an execution context that is
     allocated CPU cycles through FFA_RUN interface.
   - RTM_FFA_DIR_REQ: runtime model presented to an execution context that is
-    allocated CPU cycles through FFA_MSG_SEND_DIRECT_REQ interface.
+    allocated CPU cycles through FFA_MSG_SEND_DIRECT_REQ or FFA_MSG_SEND_DIRECT_REQ2
+    interface.
   - RTM_SEC_INTERRUPT: runtime model presented to an execution context that is
     allocated CPU cycles by SPMC to handle a secure interrupt.
   - RTM_SP_INIT: runtime model presented to an execution context that is
diff --git a/docs/threat_model_spm.rst b/docs/threat_model_spm.rst
index d0b16da..fffe87c 100644
--- a/docs/threat_model_spm.rst
+++ b/docs/threat_model_spm.rst
@@ -893,10 +893,11 @@
 |                        | SPMC and SPs, potentially leading to illegal state |
 |                        | transitions and deadlocks.**                       |
 |                        | An endpoint can call into another endpoint         |
-|                        | execution context using FFA_MSG_SEND_DIRECT_REQ    |
-|                        | ABI to create a call chain. A malicious endpoint   |
-|                        | could abuse this to form loops in a call chain that|
-|                        | could lead to potential deadlocks.                 |
+|                        | execution context using FFA_MSG_SEND_DIRECT_REQ (or|
+|                        | FFA_MSG_SEND_DIRECT_REQ2) ABI to create a call     |
+|                        | chain. A malicious endpoint could abuse this to    |
+|                        | form loops in a call chain that could lead to      |
+|                        | potential deadlocks.                               |
 +------------------------+----------------------------------------------------+
 | ``Diagram Elements``   | DF1, DF2, DF4                                      |
 +------------------------+----------------------------------------------------+