meta-arm/documentation/trusted-services.md

The Trusted Services: framework for developing root-of-trust services

meta-arm layer includes recipes for [Trusted Services]^1 Secure Partitions and Normal World applications in meta-arm/recipes-security/trusted-services

Secure Partitions recipes

We define dedicated recipes for all supported Trusted Services (TS) Secure Partitions. These recipes produce ELF and DTB files for SPs. These files are automatically included into optee-os image accordingly to defined MACHINE_FEATURES.

How to include TS SPs

To include TS SPs into optee-os image you need to add into MACHINE_FEATURES features for each [Secure Partition]^2 you would like to include:

Secure Partition	MACHINE_FEATURE
Attestation	ts-attesation
Crypto	ts-crypto
Firmware Update	ts-fwu
Internal Storage	ts-its
Protected Storage	ts-storage
se-proxy	ts-se-proxy
smm-gateway	ts-smm-gateway
spm-test[1-4]	optee-spmc-test
Logging	ts-logging

Other steps depend on your machine/platform definition:

1. For communications between Secure and Normal Words Linux kernel option CONFIG_ARM_FFA_TRANSPORT=y is required. If your platform doesn't include it already you can add arm-ffa into MACHINE_FEATURES. (Please see meta-arm/recipes-kernel/arm-tstee.)

For running the uefi-test or the xtest -t ffa_spmc tests under Linux the arm-ffa-user drivel is required. This is enabled if the ts-smm-gateway and/or the optee-spmc-test machine features are enabled. (Please see meta-arm/recipes-kernel/arm-ffa-user.)

1. optee-os might require platform specific OP-TEE build parameters (for example what SEL the SPM Core is implemented at). You can find examples in meta-arm/recipes-security/optee/optee-os_%.bbappend for qemuarm64-secureboot machine and in meta-arm-bsp/recipes-security/optee/optee-os-corstone1000-common.inc for the Corstone1000 platform.

2. trusted-firmware-a might require platform specific TF-A build parameters (SPD and SPMC details on the platform). See meta-arm/recipes-bsp/trusted-firmware-a/trusted-firmware-a_%.bbappend for qemuarm64-secureboot machine and in meta-arm-bsp/recipes-bsp/trusted-firmware-a/trusted-firmware-a-corstone1000.inc for theCorstone1000 platform.

3. Trusted Services supports an SPMC agonistic binary format. To build SPs to this format the TS_ENV variable is to be set to sp. The resulting SP binaries should be able to boot under any FF-A v1.1 compliant SPMC implementation.

Normal World applications

Optionally for testing purposes you can add packagegroup-ts-tests into your image. It includes [Trusted Services test and demo tools]^3 and [xtest]^4 configured to include the ffa_spmc tests.

OEQA Trusted Services tests

meta-arm also includes Trusted Service OEQA tests which can be used for automated testing. See ci/trusted-services.yml for an example how to include them into an image.

Configuration options

Some TS recipes support yocto variables to set build configuration. These variables can be set in .conf files (machine specific or local.conf), or .bbappend files.

SmmGW SP recipe supports the following configuration variables

Variable name	Type	Description
SMMGW_AUTH_VAR	Bool	Enable Authenticated variable support
SMMGW_INTERNAL_CRYPTO	Bool	Use MbedTLS build into SmmGW for authentication related crypto operations. Depends on SMMGW_AUTH_VAR=1

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