diff --git a/docs/components/el3-spmc.rst b/docs/components/el3-spmc.rst
new file mode 100644
index 0000000..1a2d427
--- /dev/null
+++ b/docs/components/el3-spmc.rst
@@ -0,0 +1,597 @@
+EL3 Secure Partition Manager
+****************************
+
+.. contents::
+
+Foreword
+========
+
+This document describes the design of the EL3 SPMC based on the FF-A specification.
+EL3 SPMC provides reference FF-A compliant implementation without S-EL2 virtualization support,
+to help adopt and migrate to FF-A early.
+EL3 SPMC implementation in TF-A:
+
+- Manages a single S-EL1 Secure Partition
+- Provides a standard protocol for communication and memory sharing between FF-A endpoints.
+- Provides support for EL3 Logical Partitions to support easy migration from EL3 to S-EL1.
+
+Sample reference stack
+======================
+
+The following diagram illustrates a possible configuration when the
+FEAT_SEL2 architecture extension is not implemented, showing the SPMD
+and SPMC at EL3, one S-EL1 secure partition, with an optional
+Hypervisor:
+
+.. image:: ../resources/diagrams/ff-a-spm-at-el3.png
+
+TF-A build options
+==================
+
+This section explains the TF-A build options involved in building
+an FF-A based SPM where the SPMD and SPMC are located at EL3:
+
+- **SPD=spmd**: this option selects the SPMD component to relay the FF-A
+  protocol from NWd to SWd back and forth. It is not possible to
+  enable another Secure Payload Dispatcher when this option is chosen.
+- **SPMC_AT_EL3**: this option adjusts the SPMC exception level to being
+  at EL3.
+- **ARM_SPMC_MANIFEST_DTS**: this option specifies a manifest file
+  providing SP description. It is required when
+  ``SPMC_AT_EL3`` is enabled, the secure partitions are loaded
+  by BL2 on behalf of the SPMC.
+
+Notes:
+
+- BL32 option is re-purposed to specify the S-EL1 TEE or SP image.
+  BL32 option can be omitted if using TF-A Test Secure Payload as SP.
+- BL33 option can specify the TFTF binary or a normal world loader
+  such as U-Boot or the UEFI framework payload.
+
+Sample TF-A build command line when the SPMC is located at EL3:
+
+.. code:: shell
+
+    make \
+    CROSS_COMPILE=aarch64-none-elf- \
+    SPD=spmd \
+    SPMD_SPM_AT_SEL2=0 \
+    SPMC_AT_EL3=1 \
+    BL32=<path-to-tee-binary> (opt for TSP) \
+    BL33=<path-to-bl33-binary> \
+    PLAT=fvp \
+    all fip
+
+FVP model invocation
+====================
+
+Sample FVP command line invocation:
+
+.. code:: shell
+
+    <path-to-fvp-model>/FVP_Base_RevC-2xAEMvA -C pctl.startup=0.0.0.0 \
+    -C cluster0.NUM_CORES=4 -C cluster1.NUM_CORES=4 -C bp.secure_memory=1 \
+    -C bp.secureflashloader.fname=trusted-firmware-a/build/fvp/debug/bl1.bin \
+    -C bp.flashloader0.fname=trusted-firmware-a/build/fvp/debug/fip.bin \
+    -C bp.pl011_uart0.out_file=fvp-uart0.log -C bp.pl011_uart1.out_file=fvp-uart1.log \
+    -C bp.pl011_uart2.out_file=fvp-uart2.log -C bp.vis.disable_visualisation=1
+
+
+Platform Guide
+==============
+
+- Platform Hooks  See - `[4]`_
+
+  - plat_spmc_shmem_begin
+  - plat_spmc_shmem_reclaim
+
+SPMC provides platform hooks related to memory management interfaces.
+These hooks can be used for platform specific implementations like
+for managing access control, programming TZ Controller or MPUs.
+These hooks are called by SPMC before the initial share request completes,
+and after the final reclaim has been completed.
+
+- Datastore
+
+  - plat_spmc_shmem_datastore_get
+
+    EL3 SPMC uses datastore for tracking memory transaction descriptors.
+    On FVP platform datastore is allocated from TZC DRAM section.
+    Other platforms need to allocate a similar secure memory region
+    to be used as shared memory datastore.
+
+    The accessor function is used during SPMC initialization to obtain
+    address and size of the datastore.
+    SPMC will also zero out the provided memory region.
+
+- Platform Defines See - `[5]`_
+
+  - SECURE_PARTITION_COUNT
+    Number of Secure Partitions supported: must be 1.
+
+  - NS_PARTITION_COUNT
+    Number of NWd Partitions supported.
+
+  - MAX_EL3_LP_DESCS_COUNT
+    Number of Logical Partitions supported.
+
+Logical Secure Partition (LSP)
+==============================
+
+- The SPMC provides support for statically allocated EL3 Logical Secure Partitions
+  as per FF-A v1.1 specification.
+- The DECLARE_LOGICAL_PARTITION macro can be used to add a LSP.
+- For reference implementation See - `[2]`_
+
+.. image:: ../resources/diagrams/ff-a-lsp-at-el3.png
+
+SPMC boot
+=========
+
+The SPMD and SPMC are built into the BL31 image along with TF-A's runtime components.
+BL2 loads the BL31 image as a part of (secure) boot process.
+
+The SPMC manifest is loaded by BL2 as the ``TOS_FW_CONFIG`` image `[9]`_.
+
+BL2 passes the SPMC manifest address to BL31 through a register.
+
+At boot time, the SPMD in BL31 runs from the primary core, initializes the core
+contexts and launches the SPMC passing the following information through
+registers:
+
+- X0 holds the SPMC manifest blob address.
+- X4 holds the currently running core linear id.
+
+Parsing SP partition manifests
+------------------------------
+
+SPMC consumes the SP manifest, as defined in `[7]`_.
+SP manifest fields align with Hafnium SP manifest for easy porting.
+
+.. code:: shell
+
+	compatible = "arm,ffa-manifest-1.0";
+
+	ffa-version = <0x00010001>; /* 31:16 - Major, 15:0 - Minor */
+	id = <0x8001>;
+	uuid = <0x6b43b460 0x74a24b78 0xade24502 0x40682886>;
+	messaging-method = <0x3>; /* Direct Messaging Only */
+	exception-level = <0x2>;  /* S-EL1 */
+	execution-state = <0>;
+	execution-ctx-count = <8>;
+	gp-register-num = <0>;
+	power-management-messages = <0x7>;
+
+
+Passing boot data to the SP
+---------------------------
+
+In `[1]`_ , the section  "Boot information protocol" defines a method for passing
+data to the SPs at boot time. It specifies the format for the boot information
+descriptor and boot information header structures, which describe the data to be
+exchanged between SPMC and SP.
+The specification also defines the types of data that can be passed.
+The aggregate of both the boot info structures and the data itself is designated
+the boot information blob, and is passed to a Partition as a contiguous memory
+region.
+
+Currently, the SPM implementation supports the FDT type which is used to pass the
+partition's DTB manifest.
+
+The region for the boot information blob is statically allocated (4K) by SPMC.
+BLOB contains Boot Info Header, followed by SP Manifest contents.
+
+The configuration of the boot protocol is done in the SP manifest. As defined by
+the specification, the manifest field 'gp-register-num' configures the GP register
+which shall be used to pass the address to the partitions boot information blob when
+booting the partition.
+
+Supported interfaces
+====================
+
+The following interfaces are exposed to SPs only:
+
+-  ``FFA_MSG_WAIT``
+-  ``FFA_MEM_RETRIEVE_REQ``
+-  ``FFA_MEM_RETRIEVE_RESP``
+-  ``FFA_MEM_RELINQUISH``
+-  ``FFA_SECONDARY_EP_REGISTER``
+
+The following interfaces are exposed to both NS Client and SPs:
+
+-  ``FFA_VERSION``
+-  ``FFA_FEATURES``
+-  ``FFA_RX_RELEASE``
+-  ``FFA_RXTX_MAP``
+-  ``FFA_RXTX_UNMAP``
+-  ``FFA_PARTITION_INFO_GET``
+-  ``FFA_ID_GET``
+-  ``FFA_MSG_SEND_DIRECT_REQ``
+-  ``FFA_MSG_SEND_DIRECT_RESP``
+-  ``FFA_MEM_FRAG_TX``
+-  ``FFA_SPM_ID_GET``
+
+The following additional interfaces are forwarded from SPMD to support NS Client:
+
+-  ``FFA_RUN``
+-  ``FFA_MEM_LEND``
+-  ``FFA_MEM_SHARE``
+-  ``FFA_MEM_FRAG_RX``
+-  ``FFA_MEM_RECLAIM``
+
+
+FFA_VERSION
+-----------
+
+``FFA_VERSION`` requires a *requested_version* parameter from the caller.
+SPMD forwards call to SPMC, the SPMC returns its own implemented version.
+SPMC asserts SP and SPMC are at same FF-A Version.
+
+FFA_FEATURES
+------------
+
+FF-A features supported by the SPMC may be discovered by secure partitions at
+boot (that is prior to NWd is booted) or run-time.
+
+The SPMC calling FFA_FEATURES at secure physical FF-A instance always get
+FFA_SUCCESS from the SPMD.
+
+The request made by an Hypervisor or OS kernel is forwarded to the SPMC and
+the response relayed back to the NWd.
+
+
+FFA_RXTX_MAP
+------------
+
+FFA_RXTX_UNMAP
+--------------
+
+When invoked from a secure partition FFA_RXTX_MAP maps the provided send and
+receive buffers described by their PAs to the EL3 translation regime
+as secure buffers in the MMU descriptors.
+
+When invoked from the Hypervisor or OS kernel, the buffers are mapped into the
+SPMC EL3 translation regime and marked as NS buffers in the MMU
+descriptors.
+
+The FFA_RXTX_UNMAP unmaps the RX/TX pair from the translation regime of the
+caller, either it being the Hypervisor or OS kernel, as well as a secure
+partition.
+
+FFA_PARTITION_INFO_GET
+----------------------
+
+Partition info get call can originate:
+
+- from SP to SPMC
+- from Hypervisor or OS kernel to SPMC. The request is relayed by the SPMD.
+
+The format (v1.0 or v1.1) of the populated data structure returned is based upon the
+FFA version of the calling entity.
+
+EL3 SPMC also supports returning only the count of partitions deployed.
+
+All LSPs and SP are discoverable from FFA_PARTITION_INFO_GET call made by
+either SP or NWd entities.
+
+FFA_ID_GET
+----------
+
+The FF-A ID space is split into a non-secure space and secure space:
+
+- FF-A ID with bit 15 clear relates to VMs.
+- FF-A ID with bit 15 set related to SPs or LSPs.
+- FF-A IDs 0, 0xffff, 0x8000 are assigned respectively to the Hypervisor
+  (or OS Kernel if Hyp is absent), SPMD and SPMC.
+
+This convention helps the SPM to determine the origin and destination worlds in
+an FF-A ABI invocation. In particular the SPM shall filter unauthorized
+transactions in its world switch routine. It must not be permitted for a VM to
+use a secure FF-A ID as origin world by spoofing:
+
+- A VM-to-SP direct request/response shall set the origin world to be non-secure
+  (FF-A ID bit 15 clear) and destination world to be secure (FF-A ID bit 15
+  set).
+- Similarly, an SP-to-LSP direct request/response shall set the FF-A ID bit 15
+  for both origin and destination IDs.
+
+An incoming direct message request arriving at SPMD from NWd is forwarded to
+SPMC without a specific check. The SPMC is resumed through eret and "knows" the
+message is coming from normal world in this specific code path. Thus the origin
+endpoint ID must be checked by SPMC for being a normal world ID.
+
+An SP sending a direct message request must have bit 15 set in its origin
+endpoint ID and this can be checked by the SPMC when the SP invokes the ABI.
+
+The SPMC shall reject the direct message if the claimed world in origin endpoint
+ID is not consistent:
+
+-  It is either forwarded by SPMD and thus origin endpoint ID must be a "normal
+   world ID",
+-  or initiated by an SP and thus origin endpoint ID must be a "secure world ID".
+
+
+FFA_MSG_SEND_DIRECT_REQ
+-----------------------
+
+FFA_MSG_SEND_DIRECT_RESP
+------------------------
+
+This is a mandatory interface for secure partitions participating in direct request
+and responses with the following rules:
+
+- An SP can send a direct request to LSP.
+- An LSP can send a direct response to SP.
+- An SP cannot send a direct request to an Hypervisor or OS kernel.
+- An Hypervisor or OS kernel can send a direct request to an SP or LSP.
+- An SP and LSP can send a direct response to an Hypervisor or OS kernel.
+- SPMD can send direct request to SPMC.
+
+FFA_SPM_ID_GET
+--------------
+
+Returns the FF-A ID allocated to an SPM component which can be one of SPMD
+or SPMC.
+
+At initialization, the SPMC queries the SPMD for the SPMC ID, using the
+FFA_ID_GET interface, and records it. The SPMC can also query the SPMD ID using
+the FFA_SPM_ID_GET interface at the secure physical FF-A instance.
+
+Secure partitions call this interface at the virtual FF-A instance, to which
+the SPMC returns the SPMC ID.
+
+The Hypervisor or OS kernel can issue the FFA_SPM_ID_GET call handled by the
+SPMD, which returns the SPMC ID.
+
+FFA_ID_GET
+----------
+
+Returns the FF-A ID of the calling endpoint.
+
+FFA_MEM_SHARE
+-------------
+
+FFA_MEM_LEND
+------------
+
+- If SP is borrower in the memory transaction, these calls are forwarded to SPMC.
+  SPMC performs Relayer responsibilities, caches the memory descriptors in the datastore,
+  and allocates FF-A memory handle.
+- If format of descriptor was v1.0, SPMC converts the descriptor to v1.1 before caching.
+  In case of fragmented sharing, conversion of memory descriptors happens after last
+  fragment has been received.
+- Multiple borrowers (including NWd endpoint) and fragmented memory sharing are supported.
+
+FFA_MEM_RETRIEVE_REQ
+--------------------
+
+FFA_MEM_RETRIEVE_RESP
+---------------------
+
+- Memory retrieve is supported only from SP.
+- SPMC fetches the cached memory descriptor from the datastore,
+- Performs Relayer responsiilities and sends FFA_MEM_RETRIEVE_RESP back to SP.
+- If descriptor size is more than RX buffer size, SPMC will send the descriptor in fragments.
+- SPMC will set NS Bit to 1 in memory descriptor response.
+
+FFA_MEM_FRAG_RX
+---------------
+
+FFA_MEM_FRAG_TX
+---------------
+
+FFA_MEM_FRAG_RX is to be used by:
+
+- SP if FFA_MEM_RETRIEVE_RESP returned descriptor with fragment length less than total length.
+- or by SPMC if FFA_MEM_SHARE/FFA_MEM_LEND is called with fragment length less than total length.
+
+SPMC validates handle and Endpoint ID and returns response with FFA_MEM_FRAG_TX.
+
+FFA_SECONDARY_EP_REGISTER
+-------------------------
+
+When the SPMC boots, secure partition is initialized on its primary
+Execution Context.
+
+The FFA_SECONDARY_EP_REGISTER interface is to be used by a secure partition
+from its first execution context, to provide the entry point address for
+secondary execution contexts.
+
+A secondary EC is first resumed either upon invocation of PSCI_CPU_ON from
+the NWd or by invocation of FFA_RUN.
+
+Power management
+================
+
+In platforms with or without secure virtualization:
+
+- The NWd owns the platform PM policy.
+- The Hypervisor or OS kernel is the component initiating PSCI service calls.
+- The EL3 PSCI library is in charge of the PM coordination and control
+  (eventually writing to platform registers).
+- While coordinating PM events, the PSCI library calls backs into the Secure
+  Payload Dispatcher for events the latter has statically registered to.
+
+When using the SPMD as a Secure Payload Dispatcher:
+
+- A power management event is relayed through the SPD hook to the SPMC.
+- In the current implementation CPU_ON (svc_on_finish), CPU_OFF
+  (svc_off), CPU_SUSPEND (svc_suspend) and CPU_SUSPEND_RESUME (svc_suspend_finish)
+  hooks are registered.
+
+Secure partitions scheduling
+============================
+
+The FF-A specification `[1]`_ provides two ways to relinquinsh CPU time 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_RUN interface.
+
+Additionally a secure interrupt can pre-empt the normal world execution and give
+CPU cycles by transitioning to EL3.
+
+Partition Runtime State and Model
+=================================
+
+EL3 SPMC implements Partition runtime states are described in v1.1 FF-A specification `[1]`_
+
+An SP can be in one of the following state:
+
+- RT_STATE_WAITING
+- RT_STATE_RUNNING
+- RT_STATE_PREEMPTED
+- RT_STATE_BLOCKED
+
+An SP will transition to one of the following runtime model when not in waiting state:
+
+- RT_MODEL_DIR_REQ
+- RT_MODEL_RUN
+- RT_MODEL_INIT
+- RT_MODEL_INTR
+
+Platform topology
+=================
+
+SPMC only supports a single Pinned MP S-EL1 SP. The *execution-ctx-count*
+SP manifest field should match the number of physical PE.
+
+Interrupt handling
+==================
+
+Secure Interrupt handling
+-------------------------
+
+- SPMC is capable of forwarding Secure interrupt to S-EL1 SP
+  which has preempted the normal world.
+- Interrupt is forwarded to SP using FFA_INTERRUPT interface.
+- Interrupt Number is not passed, S-EL1 SP can access the GIC registers directly.
+- Upon completion of Interrupt handling SP is expected to return to
+  SPMC using FFA_MSG_WAIT interface.
+- SPMC returns to normal world after interrupt handling is completed.
+
+In the scenario when secure interrupt occurs while the secure partition is running,
+the SPMC is not involved and the handling is implementation defined in the TOS.
+
+Non-Secure Interrupt handling
+-----------------------------
+
+The 'managed exit' scenario is the responsibility of the TOS and the SPMC is not involved.
+
+Test Secure Payload (TSP)
+=========================
+
+- TSP provides reference implementation of FF-A programming model.
+- TSP has the following support:
+
+  - SP initialization on all CPUs.
+  - Consuming Power Messages including CPU_ON, CPU_OFF, CPU_SUSPEND, CPU_SUSPEND_RESUME.
+  - Event Loop to receive Direct Requests.
+  - Sending Direct Response.
+  - Memory Sharing helper library.
+  - Ability to handle secure interrupt (timer).
+
+TSP Tests in CI
+---------------
+
+- TSP Tests are exercised in the TF-A CI using prebuilt FF-A Linux Test driver in NWd.
+- Expected output:
+
+.. code:: shell
+
+        #ioctl 255
+        Test: Echo Message to SP.
+        Status: Completed Test Case: 1
+        Test Executed Successfully
+
+        Test: Message Relay vis SP to EL3 LSP.
+        Status: Completed Test Case: 2
+        Test Executed Successfully
+
+        Test: Memory Send.
+        Verified 1 constituents successfully
+        Status: Completed Test Case: 3
+        Test Executed Successfully
+
+        Test: Memory Send in Fragments.
+        Verified 256 constituents successfully
+        Status: Completed Test Case: 4
+        Test Executed Successfully
+
+        Test: Memory Lend.
+        Verified 1 constituents successfully
+        Status: Completed Test Case: 5
+        Test Executed Successfully
+
+        Test: Memory Lend in Fragments.
+        Verified 256 constituents successfully
+        Status: Completed Test Case: 6
+        Test Executed Successfully
+
+        Test: Memory Send with Multiple Endpoints.
+        random: fast init done
+        Verified 256 constituents successfully
+        Status: Completed Test Case: 7
+        Test Executed Successfully
+
+        Test: Memory Lend with Multiple Endpoints.
+        Verified 256 constituents successfully
+        Status: Completed Test Case: 8
+        Test Executed Successfully
+
+        Test: Ensure Duplicate Memory Send Requests are Rejected.
+        Status: Completed Test Case: 9
+        Test Executed Successfully
+
+        Test: Ensure Duplicate Memory Lend Requests are Rejected.
+        Status: Completed Test Case: 10
+        Test Executed Successfully
+
+        0 Tests Failed
+
+        Exiting Test Application -  Total Failures: 0
+
+
+References
+==========
+
+.. _[1]:
+
+[1] `Arm Firmware Framework for Arm A-profile <https://developer.arm.com/docs/den0077/latest>`__
+
+.. _[2]:
+
+[2] https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/tree/plat/arm/board/fvp/fvp_el3_spmc_logical_sp.c
+
+.. _[3]:
+
+[3] `Trusted Boot Board Requirements
+Client <https://developer.arm.com/documentation/den0006/d/>`__
+
+.. _[4]:
+
+[4] https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/tree/plat/arm/board/fvp/fvp_el3_spmc.c
+
+.. _[5]:
+
+[5] https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/tree/plat/arm/board/fvp/include/platform_def.h
+
+.. _[6]:
+
+[6] https://trustedfirmware-a.readthedocs.io/en/latest/components/ffa-manifest-binding.html
+
+.. _[7]:
+
+[7] https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/tree/plat/arm/board/fvp/fdts/fvp_tsp_sp_manifest.dts
+
+.. _[8]:
+
+[8] https://lists.trustedfirmware.org/archives/list/tf-a@lists.trustedfirmware.org/thread/CFQFGU6H2D5GZYMUYGTGUSXIU3OYZP6U/
+
+.. _[9]:
+
+[9] https://trustedfirmware-a.readthedocs.io/en/latest/design/firmware-design.html#dynamic-configuration-during-cold-boot
+
+--------------
+
+*Copyright (c) 2020-2022, Arm Limited and Contributors. All rights reserved.*
diff --git a/docs/components/index.rst b/docs/components/index.rst
index 192773f..0972a68 100644
--- a/docs/components/index.rst
+++ b/docs/components/index.rst
@@ -20,6 +20,7 @@
    romlib-design
    sdei
    secure-partition-manager
+   el3-spmc
    secure-partition-manager-mm
    xlat-tables-lib-v2-design
    cot-binding
diff --git a/docs/glossary.rst b/docs/glossary.rst
index e5d379c..e6b0239 100644
--- a/docs/glossary.rst
+++ b/docs/glossary.rst
@@ -98,6 +98,9 @@
       A collaborative engineering organization consolidating
       and optimizing open source software and tools for the Arm architecture.
 
+   LSP
+      A logical secure partition managed by SPM
+
    MMU
       Memory Management Unit
 
diff --git a/docs/resources/diagrams/ff-a-lsp-at-el3.png b/docs/resources/diagrams/ff-a-lsp-at-el3.png
new file mode 100644
index 0000000..7cff34f
--- /dev/null
+++ b/docs/resources/diagrams/ff-a-lsp-at-el3.png
Binary files differ
diff --git a/docs/resources/diagrams/ff-a-spm-at-el3.png b/docs/resources/diagrams/ff-a-spm-at-el3.png
new file mode 100644
index 0000000..3b263b0
--- /dev/null
+++ b/docs/resources/diagrams/ff-a-spm-at-el3.png
Binary files differ
diff --git a/docs/resources/diagrams/plantuml/el3_spm_dfd.puml b/docs/resources/diagrams/plantuml/el3_spm_dfd.puml
new file mode 100644
index 0000000..c716180
--- /dev/null
+++ b/docs/resources/diagrams/plantuml/el3_spm_dfd.puml
@@ -0,0 +1,78 @@
+/'
+ ' Copyright (c) 2022, Arm Limited. All rights reserved.
+ '
+ ' SPDX-License-Identifier: BSD-3-Clause
+ '/
+
+/'
+TF-A EL3 SPMC Data Flow Diagram
+'/
+
+@startuml
+digraph tfa_el3_dfd {
+
+    # Allow arrows to end on cluster boundaries
+    compound=true
+    concentrate=false
+    newrank=true
+
+    # Default settings for edges and nodes
+    edge [minlen=2 color="#8c1b07"]
+    node [fillcolor="#ffb866" style=filled shape=box fixedsize=true width=1.6 height=0.7]
+
+    # Nodes outside of the trust boundary
+    nsec [label="NS Client"]
+    ddr  [label="External memory (DDR)"]
+
+    {rank="same" smmu, spmd}
+    # Trust boundary cluster
+    subgraph cluster_trusted {
+        graph [style=dashed color="#f22430"]
+        concentrate=false
+
+        # HW IPs cluster
+        subgraph cluster_ip {
+            label ="Hardware IPs";
+            graph [style=filled color="#000000" fillcolor="#ffd29e"]
+
+            rank="same"
+            gic [label="GIC" width=1.2 height=0.5]
+            smmu [label="SMMU" width=1.2 height=0.5]
+            uart [label="UART" width=1.2 height=0.5]
+            pe [label="PE" width=1.2 height=0.5]
+        }
+
+        # TF-A cluster
+        subgraph cluster_tfa {
+            label ="EL3 monitor";
+            graph [style=filled color="#000000" fillcolor="#faf9cd"]
+            {rank="same" spmc, bl31}
+            {rank="same" spmd, lsp}
+            spmc [label="SPMC" fillcolor="#ddffb3"]
+            bl31 [label="BL31" fillcolor="#ddffb3"];
+            spmd [label="SPMD" fillcolor="#ddffb3"]
+            lsp[label="LSP1" fillcolor="#ddffb3"]
+        }
+        bl2 [label="BL2" width=1.2 height=0.5]
+    }
+
+    # Secure Partitions cluster
+    subgraph cluster_sp {
+        label ="Secure Partitions";
+        graph [style=filled color="#000000" fillcolor="#faf9cd"]
+
+        sp1 [label="SP1" fillcolor="#ddffb3"]
+    }
+
+    sp1 -> spmc [dir="both" label="DF1"]
+    lsp -> spmc [dir="both" label="DF4"]
+    spmc -> spmd [dir="both" label="DF2"]
+    spmd -> nsec [dir="both" label="DF3"]
+    spmc -> smmu [lhead=cluster_spmc label="DF5"]
+    bl2 -> spmc [lhead=cluster_spmc label="DF6"]
+    bl2 -> sp1 [lhead=cluster_spmc label="DF6"]
+    sp1 -> ddr [dir="both"  label="DF7"]
+    spmc -> ddr [dir="both"  label="DF7"]
+}
+
+@enduml
diff --git a/docs/threat_model/index.rst b/docs/threat_model/index.rst
index 335937e..9d84f5b 100644
--- a/docs/threat_model/index.rst
+++ b/docs/threat_model/index.rst
@@ -15,6 +15,7 @@
 
    threat_model
    threat_model_spm
+   threat_model_el3_spm
    threat_model_fvp_r
 
 --------------
diff --git a/docs/threat_model/threat_model_el3_spm.rst b/docs/threat_model/threat_model_el3_spm.rst
new file mode 100644
index 0000000..c3af7a2
--- /dev/null
+++ b/docs/threat_model/threat_model_el3_spm.rst
@@ -0,0 +1,650 @@
+EL3 SPMC Threat Model
+*********************
+
+************
+Introduction
+************
+This document provides a threat model for the TF-A `EL3 Secure Partition Manager`_
+(EL3 SPM) implementation. The EL3 SPM implementation is based on the
+`Arm Firmware Framework for Arm A-profile`_ specification.
+
+********************
+Target of Evaluation
+********************
+In this threat model, the target of evaluation is the ``Secure Partition Manager Core``
+component (SPMC) within the EL3 firmware.
+The monitor and SPMD at EL3 are covered by the `Generic TF-A threat model`_.
+
+The scope for this threat model is:
+
+- The TF-A implementation for the EL3 SPMC
+- The implementation complies with the FF-A v1.1 specification.
+- Secure partition is statically provisioned at boot time.
+- Focus on the run-time part of the life-cycle (no specific emphasis on boot
+  time, factory firmware provisioning, firmware udpate etc.)
+- Not covering advanced or invasive physical attacks such as decapsulation,
+  FIB etc.
+
+Data Flow Diagram
+=================
+Figure 1 shows a high-level data flow diagram for the SPM split into an SPMD
+and SPMC component at EL3. The SPMD mostly acts as a relayer/pass-through between
+the normal world and the secure world. It is assumed to expose small attack surface.
+
+A description of each diagram element is given in Table 1. In the diagram, the
+red broken lines indicate trust boundaries.
+
+Components outside of the broken lines are considered untrusted.
+
+.. uml:: ../resources/diagrams/plantuml/el3_spm_dfd.puml
+  :caption: Figure 1: EL3 SPMC Data Flow Diagram
+
+.. table:: Table 1: EL3 SPMC Data Flow Diagram Description
+
+  +---------------------+--------------------------------------------------------+
+  | Diagram Element     | Description                                            |
+  +=====================+========================================================+
+  | DF1                 | SP to SPMC communication. FF-A function invocation or  |
+  |                     | implementation-defined Hypervisor call.                |
+  |                     |                                                        |
+  |                     | Note:- To communicate with LSP, SP1 performs a direct  |
+  |                     | message request to SPMC targeting LSP as destination.  |
+  +---------------------+--------------------------------------------------------+
+  | DF2                 | SPMC to SPMD communication.                            |
+  +---------------------+--------------------------------------------------------+
+  | DF3                 | SPMD to NS forwarding.                                 |
+  +---------------------+--------------------------------------------------------+
+  | DF4                 | SPMC to LSP communication.                             |
+  |                     | NWd to LSP communication happens through SPMC.         |
+  |                     | LSP can send direct response SP1 or NWd through SPMC.  |
+  +---------------------+--------------------------------------------------------+
+  | DF5                 | HW control.                                            |
+  +---------------------+--------------------------------------------------------+
+  | DF6                 | Bootloader image loading.                              |
+  +---------------------+--------------------------------------------------------+
+  | DF7                 | External memory access.                                |
+  +---------------------+--------------------------------------------------------+
+
+
+***************
+Threat Analysis
+***************
+
+This threat model follows a similar methodology to the `Generic TF-A threat model`_.
+The following sections define:
+
+- Trust boundaries
+- Assets
+- Theat agents
+- Threat types
+
+Trust boundaries
+================
+
+- Normal world is untrusted.
+- Secure world and normal world are separate trust boundaries.
+- EL3 monitor, SPMD and SPMC are trusted.
+- Bootloaders (in particular BL1/BL2 if using TF-A) and run-time BL31 are
+  implicitely trusted by the usage of trusted boot.
+- EL3 monitor, SPMD, SPMC do not trust SPs.
+
+Assets
+======
+
+The following assets are identified:
+
+- SPMC state.
+- SP state.
+- Information exchange between endpoints (partition messages).
+- SPMC secrets (e.g. pointer authentication key when enabled)
+- SP secrets (e.g. application keys).
+- Scheduling cycles.
+- Shared memory.
+
+Threat Agents
+=============
+
+The following threat agents are identified:
+
+- Non-secure endpoint (referred NS-Endpoint later): normal world client at
+  NS-EL2 (Hypervisor) or NS-EL1 (VM or OS kernel).
+- Secure endpoint (referred as S-Endpoint later): typically a secure partition.
+- Hardware attacks (non-invasive) requiring a physical access to the device,
+  such as bus probing or DRAM stress.
+
+Threat types
+============
+
+The following threat categories as exposed in the `Generic TF-A threat model`_
+are re-used:
+
+- Spoofing
+- Tampering
+- Repudiation
+- Information disclosure
+- Denial of service
+- Elevation of privileges
+
+Similarly this threat model re-uses the same threat risk ratings. The risk
+analysis is evaluated based on the environment being ``Server`` or ``Mobile``.
+IOT is not evaluated as the EL3 SPMC is primarily meant for use in Client.
+
+Threat Assessment
+=================
+
+The following threats are identified by applying STRIDE analysis on each diagram
+element of the data flow diagram.
+
++------------------------+----------------------------------------------------+
+| ID                     | 01                                                 |
++========================+====================================================+
+| Threat                 | **An endpoint impersonates the sender              |
+|                        | FF-A ID in a direct request/response invocation.** |
++------------------------+----------------------------------------------------+
+| Diagram Elements       | DF1, DF2, DF3, DF4                                 |
++------------------------+----------------------------------------------------+
+| Affected TF-A          | SPMD, SPMC                                         |
+| Components             |                                                    |
++------------------------+----------------------------------------------------+
+| Assets                 | SP state                                           |
++------------------------+----------------------------------------------------+
+| Threat Agent           | NS-Endpoint, S-Endpoint                            |
++------------------------+----------------------------------------------------+
+| Threat Type            | Spoofing                                           |
++------------------------+--------------------------+-------------------------+
+| Application            |   Server                 |  Mobile                 |
++------------------------+--------------------------++------------------------+
+| Impact                 | Critical(5)              | Critical(5)             |
++------------------------+--------------------------++------------------------+
+| Likelihood             | Critical(5)              | Critical(5)             |
++------------------------+--------------------------++------------------------+
+| Total Risk Rating      | Critical(25)             | Critical(25)            |
++------------------------+--------------------------+-------------------------+
+| Mitigations            | SPMC must be able to correctly identify an         |
+|                        | endpoint and enforce checks to disallow spoofing.  |
++------------------------+----------------------------------------------------+
+| Mitigations            | Yes.                                               |
+| implemented?           | The SPMC enforces checks in the direct message     |
+|                        | request/response interfaces such an endpoint cannot|
+|                        | spoof the origin and destination worlds (e.g. a NWd|
+|                        | originated message directed to the SWd cannot use a|
+|                        | SWd ID as the sender ID).                          |
+|                        | Also enforces check for direct response being sent |
+|                        | only to originator of request.                     |
++------------------------+----------------------------------------------------+
+
++------------------------+----------------------------------------------------+
+| ID                     | 02                                                 |
++========================+====================================================+
+| Threat                 | **An endpoint impersonates the receiver            |
+|                        | FF-A ID in a direct request/response invocation.** |
++------------------------+----------------------------------------------------+
+| Diagram Elements       | DF1, DF2, DF3, DF4                                 |
++------------------------+----------------------------------------------------+
+| Affected TF-A          | SPMD, SPMC                                         |
+| Components             |                                                    |
++------------------------+----------------------------------------------------+
+| Assets                 | SP state                                           |
++------------------------+----------------------------------------------------+
+| Threat Agent           | NS-Endpoint, S-Endpoint                            |
++------------------------+----------------------------------------------------+
+| Threat Type            | Spoofing, Denial of Service                        |
++------------------------+--------------------------+-------------------------+
+| Application            |   Server                 |  Mobile                 |
++------------------------+--------------------------++------------------------+
+| Impact                 | Critical(5)              | Critical(5)             |
++------------------------+--------------------------++------------------------+
+| Likelihood             | Critical(5)              | Critical(5)             |
++------------------------+--------------------------++------------------------+
+| Total Risk Rating      | Critical(25)             | Critical(25)            |
++------------------------+--------------------------+-------------------------+
+| Mitigations            | Validate if endpoind has permission to send        |
+|                        | request to other endpoint by implementation        |
+|                        | defined means.                                     |
++------------------------+----------------------------------------------------+
+| Mitigations            | Platform specific.                                 |
+| implemented?           |                                                    |
+|                        | The guidance below is left for a system integrator |
+|                        | to implement as necessary.                         |
+|                        |                                                    |
+|                        | Additionally a software component residing in the  |
+|                        | SPMC can be added for the purpose of direct        |
+|                        | request/response filtering.                        |
+|                        |                                                    |
+|                        | It can be configured with the list of known IDs    |
+|                        | and about which interaction can occur between one  |
+|                        | and another endpoint (e.g. which NWd endpoint ID   |
+|                        | sends a direct request to which SWd endpoint ID).  |
+|                        |                                                    |
+|                        | This component checks the sender/receiver fields   |
+|                        | for a legitimate communication between endpoints.  |
+|                        |                                                    |
+|                        | A similar component can exist in the OS kernel     |
+|                        | driver, or Hypervisor although it remains untrusted|
+|                        | by the SPMD/SPMC.                                  |
++------------------------+----------------------------------------------------+
+
++------------------------+----------------------------------------------------+
+| ID                     | 03                                                 |
++========================+====================================================+
+| Threat                 | **Tampering with memory shared between an endpoint |
+|                        | and the SPMC.**                                    |
+|                        |                                                    |
+|                        | A malicious endpoint may attempt tampering with its|
+|                        | RX/TX buffer contents while the SPMC is processing |
+|                        | it (TOCTOU).                                       |
++------------------------+----------------------------------------------------+
+| Diagram Elements       | DF1, DF3, DF7                                      |
++------------------------+----------------------------------------------------+
+| Affected TF-A          | SPMC                                               |
+| Components             |                                                    |
++------------------------+----------------------------------------------------+
+| Assets                 | Shared memory, Information exchange                |
++------------------------+----------------------------------------------------+
+| Threat Agent           | NS-Endpoint, S-Endpoint                            |
++------------------------+----------------------------------------------------+
+| Threat Type            | Tampering                                          |
++------------------------+--------------------------+-------------------------+
+| Application            |   Server                 |    Mobile               |
++------------------------+--------------------------+-------------------------+
+| Impact                 | High (4)                 | High (4)                |
++------------------------+--------------------------+-------------------------+
+| Likelihood             | High (4)                 | High (4)                |
++------------------------+--------------------------+-------------------------+
+| Total Risk Rating      | High (16)                | High (16)               |
++------------------------+--------------------------+-------------------------+
+| Mitigations            | Validate all inputs, copy before use.              |
++------------------------+----------------------------------------------------+
+| Mitigations            | Yes. In context of FF-A v1.1 this is the case of   |
+| implemented?           | sharing the RX/TX buffer pair and usage in the     |
+|                        | PARTITION_INFO_GET or memory sharing primitives.   |
+|                        |                                                    |
+|                        | The SPMC copies the contents of the TX buffer      |
+|                        | to an internal temporary buffer before processing  |
+|                        | its contents. The SPMC implements hardened input   |
+|                        | validation on data transmitted through the TX      |
+|                        | buffer by an untrusted endpoint.                   |
+|                        |                                                    |
+|                        | The TF-A SPMC enforces                             |
+|                        | checks on data transmitted through RX/TX buffers.  |
++------------------------+----------------------------------------------------+
+
++------------------------+----------------------------------------------------+
+| ID                     | 04                                                 |
++========================+====================================================+
+| Threat                 | **An endpoint may tamper with its own state or the |
+|                        | state of another endpoint.**                       |
+|                        |                                                    |
+|                        | A malicious endpoint may attempt violating:        |
+|                        |                                                    |
+|                        | - its own or another SP state by using an unusual  |
+|                        |   combination (or out-of-order) FF-A function      |
+|                        |   invocations.                                     |
+|                        |   This can also be an endpoint emitting FF-A       |
+|                        |   function invocations to another endpoint while   |
+|                        |   the latter in not in a state to receive it (e.g. |
+|                        |   SP sends a direct request to the normal world    |
+|                        |   early while the normal world is not booted yet). |
+|                        | - the SPMC state itself by employing unexpected    |
+|                        |   transitions in FF-A memory sharing, direct       |
+|                        |   requests and responses, or handling of interrupts|
+|                        |   This can be led by random stimuli injection or   |
+|                        |   fuzzing.                                         |
++------------------------+----------------------------------------------------+
+| Diagram Elements       | DF1, DF2, DF3                                      |
++------------------------+----------------------------------------------------+
+| Affected TF-A          | SPMD, SPMC                                         |
+| Components             |                                                    |
++------------------------+----------------------------------------------------+
+| Assets                 | SP state, SPMC state                               |
++------------------------+----------------------------------------------------+
+| Threat Agent           | NS-Endpoint, S-Endpoint                            |
++------------------------+----------------------------------------------------+
+| Threat Type            | Tampering                                          |
++------------------------+--------------------------+-------------------------+
+| Application            |   Server                 |   Mobile                |
++------------------------+--------------------------+-------------------------+
+| Impact                 | High (4)                 | High (4)                |
++------------------------+--------------------------+-------------------------+
+| Likelihood             | Medium (3)               | Medium (3)              |
++------------------------+--------------------------+-------------------------+
+| Total Risk Rating      | High (12)                | High (12)               |
++------------------------+------------------+-----------------+---------------+
+| Mitigations            | Follow guidelines in FF-A v1.1 specification on    |
+|                        | state transitions (run-time model).                |
++------------------------+----------------------------------------------------+
+| Mitigations            | Yes. The TF-A SPMC is hardened to follow this      |
+| implemented?           | guidance.                                          |
++------------------------+----------------------------------------------------+
+
++------------------------+----------------------------------------------------+
+| ID                     | 05                                                 |
++========================+====================================================+
+| Threat                 | **Replay fragments of past communication between   |
+|                        | endpoints.**                                       |
+|                        |                                                    |
+|                        | A malicious endpoint may replay a message exchange |
+|                        | that occurred between two legitimate endpoints as  |
+|                        | a matter of triggering a malfunction or extracting |
+|                        | secrets from the receiving endpoint. In particular |
+|                        | the memory sharing operation with fragmented       |
+|                        | messages between an endpoint and the SPMC may be   |
+|                        | replayed by a malicious agent as a matter of       |
+|                        | getting access or gaining permissions to a memory  |
+|                        | region which does not belong to this agent.        |
++------------------------+----------------------------------------------------+
+| Diagram Elements       | DF2, DF3                                           |
++------------------------+----------------------------------------------------+
+| Affected TF-A          | SPMC                                               |
+| Components             |                                                    |
++------------------------+----------------------------------------------------+
+| Assets                 | Information exchange                               |
++------------------------+----------------------------------------------------+
+| Threat Agent           | NS-Endpoint, S-Endpoint                            |
++------------------------+----------------------------------------------------+
+| Threat Type            | Repudiation                                        |
++------------------------+--------------------------+-------------------------+
+| Application            |     Server               |    Mobile               |
++------------------------+--------------------------+-------------------------+
+| Impact                 | Medium (3)               | Medium (3)              |
++------------------------+--------------------------+-------------------------+
+| Likelihood             | High (4)                 | High (4)	              |
++------------------------+--------------------------+-------------------------+
+| Total Risk Rating      | High (12)                | High (12)               |
++------------------------+--------------------------+-------------------------+
+| Mitigations            | Strict input validation and state tracking.        |
++------------------------+----------------------------------------------------+
+| Mitigations            | Platform specific.                                 |
+| implemented?           |                                                    |
++------------------------+----------------------------------------------------+
+
++------------------------+----------------------------------------------------+
+| ID                     | 06                                                 |
++========================+====================================================+
+| Threat                 | **A malicious endpoint may attempt to extract data |
+|                        | or state information by the use of invalid or      |
+|                        | incorrect input arguments.**                       |
+|                        |                                                    |
+|                        | Lack of input parameter validation or side effects |
+|                        | of maliciously forged input parameters might affect|
+|                        | the SPMC.                                          |
++------------------------+----------------------------------------------------+
+| Diagram Elements       | DF1, DF2, DF3                                      |
++------------------------+----------------------------------------------------+
+| Affected TF-A          | SPMD, SPMC                                         |
+| Components             |                                                    |
++------------------------+----------------------------------------------------+
+| Assets                 | SP secrets, SPMC secrets, SP state, SPMC state     |
++------------------------+----------------------------------------------------+
+| Threat Agent           | NS-Endpoint, S-Endpoint                            |
++------------------------+----------------------------------------------------+
+| Threat Type            | Information discolure                              |
++------------------------+--------------------------+-------------------------+
+| Application            |   Server                 |  Mobile                 |
++------------------------+--------------------------+-------------------------+
+| Impact                 | High (4)                 | High (4)                |
++------------------------+--------------------------+-------------------------+
+| Likelihood             | Medium (3)               | Medium (3)              |
++------------------------+--------------------------+-------------------------+
+| Total Risk Rating      | High (12)                | High (12)               |
++------------------------+--------------------------+-------------------------+
+| Mitigations            | SPMC must be prepared to receive incorrect input   |
+|                        | data from secure partitions and reject them        |
+|                        | appropriately.                                     |
+|                        | The use of software (canaries) or hardware         |
+|                        | hardening techniques (XN, WXN, pointer             |
+|                        | authentication) helps detecting and stopping       |
+|                        | an exploitation early.                             |
++------------------------+----------------------------------------------------+
+| Mitigations            | Yes. The TF-A SPMC mitigates this threat by        |
+| implemented?           | implementing stack protector, pointer              |
+|                        | authentication, XN, WXN, security hardening        |
+|                        | techniques.                                        |
++------------------------+----------------------------------------------------+
+
++------------------------+----------------------------------------------------+
+| ID                     | 07                                                 |
++========================+====================================================+
+| Threat                 | **A malicious endpoint may forge a direct message  |
+|                        | request such that it reveals the internal state of |
+|                        | another endpoint through the direct message        |
+|                        | response.**                                        |
+|                        |                                                    |
+|                        | The secure partition or SPMC replies to a partition|
+|                        | message by a direct message response with          |
+|                        | information which may reveal its internal state    |
+|                        | (e.g. partition message response outside of        |
+|                        | allowed bounds).                                   |
++------------------------+----------------------------------------------------+
+| Diagram Elements       | DF1, DF2, DF3                                      |
++------------------------+----------------------------------------------------+
+| Affected TF-A          | SPMC                                               |
+| Components             |                                                    |
++------------------------+----------------------------------------------------+
+| Assets                 | SPMC or SP state                                   |
++------------------------+----------------------------------------------------+
+| Threat Agent           | NS-Endpoint, S-Endpoint                            |
++------------------------+----------------------------------------------------+
+| Threat Type            | Information discolure                              |
++------------------------+--------------------------+-------------------------+
+| Application            |   Server                 |  Mobile                 |
++------------------------+--------------------------+-------------------------+
+| Impact                 | Medium (3)               | Medium (3)              |
++------------------------+--------------------------+-------------------------+
+| Likelihood             | Low (2)                  | Low (2)	              |
++------------------------+--------------------------+-------------------------+
+| Total Risk Rating      | Medium (6)               | Medium (6)              |
++------------------------+--------------------------+-------------------------+
+| Mitigations            | Follow FF-A specification about state transitions, |
+|                        | run time model, do input validation.               |
++------------------------+----------------------------------------------------+
+| Mitigations            | Yes. For the specific case of direct requests      |
+| implemented?           | targeting the SPMC, the latter is hardened to      |
+|                        | prevent its internal state or the state of an SP   |
+|                        | to be revealed through a direct message response.  |
+|                        | Further FF-A v1.1 guidance about run time models   |
+|                        | and partition states is followed.                  |
++------------------------+----------------------------------------------------+
+
++------------------------+----------------------------------------------------+
+| ID                     | 08                                                 |
++========================+====================================================+
+| Threat                 | **Probing the FF-A communication between           |
+|                        | endpoints.**                                       |
+|                        |                                                    |
+|                        | SPMC and SPs are typically loaded to external      |
+|                        | memory (protected by a TrustZone memory            |
+|                        | controller). A malicious agent may use non invasive|
+|                        | methods to probe the external memory bus and       |
+|                        | extract the traffic between an SP and the SPMC or  |
+|                        | among SPs when shared buffers are held in external |
+|                        | memory.                                            |
++------------------------+----------------------------------------------------+
+| Diagram Elements       | DF7                                                |
++------------------------+----------------------------------------------------+
+| Affected TF-A          | SPMC                                               |
+| Components             |                                                    |
++------------------------+----------------------------------------------------+
+| Assets                 | SP/SPMC state, SP/SPMC secrets                     |
++------------------------+----------------------------------------------------+
+| Threat Agent           | Hardware attack                                    |
++------------------------+----------------------------------------------------+
+| Threat Type            | Information disclosure                             |
++------------------------+--------------------------+-------------------------+
+| Application            |   Server                 |   Mobile                |
++------------------------+--------------------------+-------------------------+
+| Impact                 | Medium (3)               | Medium (3)              |
++------------------------+--------------------------+-------------------------+
+| Likelihood             | Low (2)                  | Medium (3)              |
++------------------------+--------------------------+-------------------------+
+| Total Risk Rating      | Medium (6)               | Medium (9)              |
++------------------------+--------------------------+-------------------------+
+| Mitigations            | Implement DRAM protection techniques using         |
+|                        | hardware countermeasures at platform or chip level.|
++------------------------+--------------------------+-------------------------+
+| Mitigations            | Platform specific.                                 |
+| implemented?           |                                                    |
++------------------------+----------------------------------------------------+
+
++------------------------+----------------------------------------------------+
+| ID                     | 09                                                 |
++========================+====================================================+
+| Threat                 | **A malicious agent may attempt revealing the SPMC |
+|                        | state or secrets by the use of software-based cache|
+|                        | side-channel attack techniques.**                  |
++------------------------+----------------------------------------------------+
+| Diagram Elements       | DF7                                                |
++------------------------+----------------------------------------------------+
+| Affected TF-A          | SPMC                                               |
+| Components             |                                                    |
++------------------------+----------------------------------------------------+
+| Assets                 | SP or SPMC state                                   |
++------------------------+----------------------------------------------------+
+| Threat Agent           | NS-Endpoint, S-Endpoint                            |
++------------------------+----------------------------------------------------+
+| Threat Type            | Information disclosure                             |
++------------------------+--------------------------+-------------------------+
+| Application            |   Server                 |   Mobile                |
++------------------------+--------------------------+-------------------------+
+| Impact                 | Medium (3)               | Medium (3)              |
++------------------------+--------------------------+-------------------------+
+| Likelihood             | Low (2)                  | Low (2)                 |
++------------------------+--------------------------+-------------------------+
+| Total Risk Rating      | Medium (6)               | Medium (6)              |
++------------------------+--------------------------+-------------------------+
+| Mitigations            | The SPMC may be hardened further with SW           |
+|                        | mitigations (e.g. speculation barriers) for the    |
+|                        | cases not covered in HW. Usage of hardened         |
+|                        | compilers and appropriate options, code inspection |
+|                        | are recommended ways to mitigate Spectre types of  |
+|                        | attacks.                                           |
++------------------------+----------------------------------------------------+
+| Mitigations            | No.                                                |
+| implemented?           |                                                    |
++------------------------+----------------------------------------------------+
+
+
++------------------------+----------------------------------------------------+
+| ID                     | 10                                                 |
++========================+====================================================+
+| Threat                 | **A malicious endpoint may attempt flooding the    |
+|                        | SPMC with requests targeting a service within an   |
+|                        | endpoint such that it denies another endpoint to   |
+|                        | access this service.**                             |
+|                        |                                                    |
+|                        | Similarly, the malicious endpoint may target a     |
+|                        | a service within an endpoint such that the latter  |
+|                        | is unable to request services from another         |
+|                        | endpoint.                                          |
++------------------------+----------------------------------------------------+
+| Diagram Elements       | DF1, DF2, DF3                                      |
++------------------------+----------------------------------------------------+
+| Affected TF-A          | SPMC                                               |
+| Components             |                                                    |
++------------------------+----------------------------------------------------+
+| Assets                 | SPMC state, Scheduling cycles                      |
++------------------------+----------------------------------------------------+
+| Threat Agent           | NS-Endpoint, S-Endpoint                            |
++------------------------+----------------------------------------------------+
+| Threat Type            | Denial of service                                  |
++------------------------+--------------------------+-------------------------+
+| Application            |   Server                 |   Mobile                |
++------------------------+--------------------------+-------------------------+
+| Impact                 | Medium (3)               | Medium (3)              |
++------------------------+--------------------------+-------------------------+
+| Likelihood             | Medium (3)               | Medium (3)              |
++------------------------+--------------------------+-------------------------+
+| Total Risk Rating      | Medium (9)               | Medium (9)              |
++------------------------+--------------------------+-------------------------+
+| Mitigations            | Bounding the time for operations to complete can   |
+|                        | be achieved by the usage of a trusted watchdog.    |
+|                        | Other quality of service monitoring can be achieved|
+|                        | in the SPMC such as counting a number of operations|
+|                        | in a limited timeframe.                            |
++------------------------+----------------------------------------------------+
+| Mitigations            | Platform specific.                                 |
+| implemented?           |                                                    |
++------------------------+----------------------------------------------------+
+
++------------------------+----------------------------------------------------+
+| ID                     | 11                                                 |
++========================+====================================================+
+| Threat                 | **Denying a lender endpoint to make progress if    |
+|                        | borrower endpoint encountered a fatal exception.   |
+|                        | Denying a new sender endpoint to make progress     |
+|                        | if receiver encountered a fatal exception.**       |
++------------------------+----------------------------------------------------+
+| Diagram Elements       | DF1, DF2, DF3                                      |
++------------------------+----------------------------------------------------+
+| Affected TF-A          | SPMC                                               |
+| Components             |                                                    |
++------------------------+----------------------------------------------------+
+| Assets                 | Shared resources, Scheduling cycles.               |
++------------------------+----------------------------------------------------+
+| Threat Agent           | NS-Endpoint, S-Endpoint                            |
++------------------------+----------------------------------------------------+
+| Threat Type            | Denial of service                                  |
++------------------------+--------------------------+-------------------------+
+| Application            |   Server                 |   Mobile                |
++------------------------+--------------------------+-------------------------+
+| Impact                 | Medium (3)               | Medium (3)              |
++------------------------+--------------------------+-------------------------+
+| Likelihood             | Medium (3)               | Medium (3)              |
++------------------------+--------------------------+-------------------------+
+| Total Risk Rating      | Medium (9)               | Medium (9)              |
++------------------------+--------------------------+-------------------------+
+| Mitigations            | SPMC must be able to detect fatal error in SP and  |
+|                        | take ownership of shared resources. It should      |
+|                        | be able to relinquish the access to shared memory  |
+|                        | regions to allow lender to proceed.                |
+|                        | SPMC must return ABORTED if new direct requests are|
+|                        | targeted to SP which has had a fatal error.        |
++------------------------+----------------------------------------------------+
+| Mitigations            | Platform specific.                                 |
+| implemented?           |                                                    |
++------------------------+----------------------------------------------------+
+
++------------------------+----------------------------------------------------+
+| ID                     | 12                                                 |
++========================+====================================================+
+| Threat                 | **A malicious endpoint may attempt to donate,      |
+|                        | share, lend, relinquish or reclaim unauthorized    |
+|                        | memory region.**                                   |
++------------------------+----------------------------------------------------+
+| Diagram Elements       | DF1, DF2, DF3                                      |
++------------------------+----------------------------------------------------+
+| Affected TF-A          | SPMC                                               |
+| Components             |                                                    |
++------------------------+----------------------------------------------------+
+| Assets                 |  SP secrets, SPMC secrets, SP state, SPMC state    |
++------------------------+----------------------------------------------------+
+| Threat Agent           | NS-Endpoint, S-Endpoint                            |
++------------------------+----------------------------------------------------+
+| Threat Type            | Elevation of Privilege                             |
++------------------------+--------------------------+-------------------------+
+| Application            |   Server                 |   Mobile                |
++------------------------+--------------------------+-------------------------+
+| Impact                 | High (4)                 | High   (4)              |
++------------------------+--------------------------+-------------------------+
+| Likelihood             | High (4)                 | High (4)                |
++------------------------+--------------------------+-------------------------+
+| Total Risk Rating      | High (16)                | High (16)               |
++------------------------+--------------------------+-------------------------+
+| Mitigations            | Follow FF-A specification guidelines               |
+|                        | on Memory management transactions.                 |
++------------------------+----------------------------------------------------+
+| Mitigations            | Yes. The SPMC tracks ownership and access state    |
+| implemented?           | for memory transactions appropriately, and         |
+|                        | validating the same for all operations.            |
+|                        | SPMC follows FF-A v1.1                             |
+|                        | guidance for memory transaction lifecycle.         |
++------------------------+----------------------------------------------------+
+
+---------------
+
+*Copyright (c) 2022, Arm Limited. All rights reserved.*
+
+.. _Arm Firmware Framework for Arm A-profile: https://developer.arm.com/docs/den0077/latest
+.. _EL3 Secure Partition Manager: ../components/el3-spmc.html
+.. _Generic TF-A threat model: ./threat_model.html#threat-analysis
+.. _FF-A ACS: https://github.com/ARM-software/ff-a-acs/releases