| Secure Partition Manager |
| ************************ |
| |
| .. contents:: |
| |
| .. toctree:: |
| ffa-manifest-binding |
| |
| Acronyms |
| ======== |
| |
| +--------+--------------------------------------+ |
| | DTS | Device Tree Source | |
| +--------+--------------------------------------+ |
| | FF-A | Firmware Framework for Arm A-profile | |
| +--------+--------------------------------------+ |
| | NWd | Normal World | |
| +--------+--------------------------------------+ |
| | SP | Secure Partition | |
| +--------+--------------------------------------+ |
| | SPD | Secure Payload Dispatcher | |
| +--------+--------------------------------------+ |
| | SPM | Secure Partition Manager | |
| +--------+--------------------------------------+ |
| | SPMC | SPM Core | |
| +--------+--------------------------------------+ |
| | SPMD | SPM Dispatcher | |
| +--------+--------------------------------------+ |
| | SWd | Secure World | |
| +--------+--------------------------------------+ |
| |
| Foreword |
| ======== |
| |
| Three implementations of a Secure Partition Manager co-exist in the TF-A |
| codebase: |
| |
| #. S-EL2 SPMC based on the FF-A specification `[1]`_, enabling virtualization in |
| the secure world, managing multiple S-EL1 or S-EL0 partitions `[5]`_. |
| #. EL3 SPMC based on the FF-A specification, managing a single S-EL1 partition |
| without virtualization in the secure world `[6]`_. |
| #. EL3 SPM based on the MM specification, legacy implementation managing a |
| single S-EL0 partition `[2]`_. |
| |
| These implementations differ in their respective SW architecture and only one |
| can be selected at build time. |
| |
| Support for legacy platforms |
| ---------------------------- |
| |
| The SPM is split into a dispatcher and a core component (respectively SPMD and |
| SPMC) residing at different exception levels. To permit the FF-A specification |
| adoption and a smooth migration, the SPMD supports an SPMC residing either at |
| S-EL1 or S-EL2: |
| |
| - The SPMD is located at EL3 and mainly relays the FF-A protocol from NWd |
| (Hypervisor or OS kernel) to the SPMC. |
| - The same SPMD component is used for both S-EL1 and S-EL2 SPMC configurations. |
| - The SPMC exception level is a build time choice. |
| |
| TF-A supports both cases: |
| |
| - S-EL1 SPMC for platforms not supporting the FEAT_SEL2 architecture |
| extension. The SPMD relays the FF-A protocol from EL3 to S-EL1. |
| - S-EL2 SPMC for platforms implementing the FEAT_SEL2 architecture |
| extension. The SPMD relays the FF-A protocol from EL3 to S-EL2. |
| |
| TF-A build options |
| ================== |
| |
| This section explains the TF-A build options involved in building with |
| support for an FF-A based SPM where the SPMD is located at EL3 and the |
| SPMC located at S-EL1, S-EL2 or 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. |
| - **SPMD_SPM_AT_SEL2**: this option adjusts the SPMC exception |
| level to being at S-EL2. It defaults to enabled (value 1) when |
| SPD=spmd is chosen. |
| - **SPMC_AT_EL3**: this option adjusts the SPMC exception level to being |
| at EL3. If neither ``SPMD_SPM_AT_SEL2`` or ``SPMC_AT_EL3`` are enabled the |
| SPMC exception level is set to S-EL1. |
| ``SPMD_SPM_AT_SEL2`` is enabled. The context save/restore routine |
| and exhaustive list of registers is visible at `[4]`_. |
| - **SPMC_AT_EL3_SEL0_SP**: this option enables the support to load SEL0 SP |
| when SPMC at EL3 support is enabled. |
| - **SP_LAYOUT_FILE**: this option specifies a text description file |
| providing paths to SP binary images and manifests in DTS format |
| (see `[3]`_). It |
| is required when ``SPMD_SPM_AT_SEL2`` is enabled hence when multiple |
| secure partitions are to be loaded by BL2 on behalf of the SPMC. |
| |
| +---------------+------------------+-------------+-------------------------+ |
| | | SPMD_SPM_AT_SEL2 | SPMC_AT_EL3 | CTX_INCLUDE_EL2_REGS(*) | |
| +---------------+------------------+-------------+-------------------------+ |
| | SPMC at S-EL1 | 0 | 0 | 0 | |
| +---------------+------------------+-------------+-------------------------+ |
| | SPMC at S-EL2 | 1 (default when | 0 | 1 | |
| | | SPD=spmd) | | | |
| +---------------+------------------+-------------+-------------------------+ |
| | SPMC at EL3 | 0 | 1 | 0 | |
| +---------------+------------------+-------------+-------------------------+ |
| |
| Other combinations of such build options either break the build or are not |
| supported. |
| |
| Notes: |
| |
| - Only Arm's FVP platform is supported to use with the TF-A reference software |
| stack. |
| - When ``SPMD_SPM_AT_SEL2=1``, the reference software stack assumes enablement |
| of FEAT_PAuth, FEAT_BTI and FEAT_MTE architecture extensions. |
| - ``(*) CTX_INCLUDE_EL2_REGS``, this flag is |TF-A| internal and informational |
| in this table. When set, it provides the generic support for saving/restoring |
| EL2 registers required when S-EL2 firmware is present. |
| - BL32 option is re-purposed to specify the SPMC image. It can specify either |
| the Hafnium binary path (built for the secure world) or the path to a TEE |
| binary implementing FF-A interfaces. |
| - 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 S-EL1 |
| (e.g. when the FEAT_SEL2 architecture extension is not implemented): |
| |
| .. code:: shell |
| |
| make \ |
| CROSS_COMPILE=aarch64-none-elf- \ |
| SPD=spmd \ |
| SPMD_SPM_AT_SEL2=0 \ |
| BL32=<path-to-tee-binary> \ |
| BL33=<path-to-bl33-binary> \ |
| PLAT=fvp \ |
| all fip |
| |
| Sample TF-A build command line when FEAT_SEL2 architecture extension is |
| implemented and the SPMC is located at S-EL2: |
| |
| .. code:: shell |
| |
| make \ |
| CROSS_COMPILE=aarch64-none-elf- \ |
| PLAT=fvp \ |
| SPD=spmd \ |
| ARM_ARCH_MINOR=5 \ |
| BRANCH_PROTECTION=1 \ |
| CTX_INCLUDE_PAUTH_REGS=1 \ |
| ENABLE_FEAT_MTE2=1 \ |
| BL32=<path-to-hafnium-binary> \ |
| BL33=<path-to-bl33-binary> \ |
| SP_LAYOUT_FILE=sp_layout.json \ |
| all fip |
| |
| Sample TF-A build command line when FEAT_SEL2 architecture extension is |
| implemented, the SPMC is located at S-EL2, and enabling secure boot: |
| |
| .. code:: shell |
| |
| make \ |
| CROSS_COMPILE=aarch64-none-elf- \ |
| PLAT=fvp \ |
| SPD=spmd \ |
| ARM_ARCH_MINOR=5 \ |
| BRANCH_PROTECTION=1 \ |
| CTX_INCLUDE_PAUTH_REGS=1 \ |
| ENABLE_FEAT_MTE2=1 \ |
| BL32=<path-to-hafnium-binary> \ |
| BL33=<path-to-bl33-binary> \ |
| SP_LAYOUT_FILE=sp_layout.json \ |
| MBEDTLS_DIR=<path-to-mbedtls-lib> \ |
| TRUSTED_BOARD_BOOT=1 \ |
| COT=dualroot \ |
| ARM_ROTPK_LOCATION=devel_rsa \ |
| ROT_KEY=plat/arm/board/common/rotpk/arm_rotprivk_rsa.pem \ |
| GENERATE_COT=1 \ |
| all fip |
| |
| 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> \ |
| BL33=<path-to-bl33-binary> \ |
| PLAT=fvp \ |
| all fip |
| |
| Sample TF-A build command line when the SPMC is located at EL3 and SEL0 SP is |
| enabled: |
| |
| .. code:: shell |
| |
| make \ |
| CROSS_COMPILE=aarch64-none-elf- \ |
| SPD=spmd \ |
| SPMD_SPM_AT_SEL2=0 \ |
| SPMC_AT_EL3=1 \ |
| SPMC_AT_EL3_SEL0_SP=1 \ |
| BL32=<path-to-tee-binary> \ |
| BL33=<path-to-bl33-binary> \ |
| PLAT=fvp \ |
| all fip |
| |
| Boot process |
| ============ |
| |
| The boot process involving SPMC is highly dependent on the SPMC implementation. |
| It is recommended to refer to corresponding SPMC documentation for further |
| details. Some aspects of boot process are described here in the greater interest |
| of the project. |
| |
| SPMC boot |
| --------- |
| |
| When SPMC resides at a lower EL i.e., S-EL1 or S-EL2, it is loaded by BL2 as the |
| BL32 image. The SPMC manifest is loaded by BL2 as the ``TOS_FW_CONFIG`` image `[7]`_. |
| |
| 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 (BL32) passing the following information through registers: |
| |
| - X0 holds the ``TOS_FW_CONFIG`` physical address (or SPMC manifest blob). |
| - X1 holds the ``HW_CONFIG`` physical address. |
| - X4 holds the currently running core linear id. |
| |
| |
| References |
| ========== |
| |
| .. _[1]: |
| |
| [1] `Arm Firmware Framework for Arm A-profile <https://developer.arm.com/docs/den0077/latest>`__ |
| |
| .. _[2]: |
| |
| [2] :ref:`Secure Partition Manager using MM interface<Secure Partition Manager (MM)>` |
| |
| .. _[3]: |
| |
| [3] https://hafnium.readthedocs.io/en/latest/secure-partition-manager/secure-partition-manager.html#secure-partitions-layout-file |
| |
| .. _[4]: |
| |
| [4] https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/tree/lib/el3_runtime/aarch64/context.S#n45 |
| |
| .. _[5]: |
| |
| [5] https://hafnium.readthedocs.io/en/latest/secure-partition-manager/index.html |
| |
| .. _[6]: |
| |
| [6] :ref:`EL3 Secure Partition Manager<EL3 Secure Partition Manager>` |
| |
| .. _[7]: |
| |
| [7] https://trustedfirmware-a.readthedocs.io/en/latest/design/firmware-design.html#dynamic-configuration-during-cold-boot |
| |
| -------------- |
| |
| *Copyright (c) 2020-2024, Arm Limited and Contributors. All rights reserved.* |