Hi All,

As part of the work we are doing for Hybrid Platforms we prepared a patch that makes changes how the Non-Secure Client IDs are handled.

When TF-M is run in Hybrid Platform configuration, It has multiple NS agents active the same time. Each of the NS clients (either running in the NSPE the same v8M CPU as SPM, or on the other end of a Mailbox) can have their own way to assign NS Client IDs to clients. To prevent NS clients impersonate other NS clients that are accessing secure services through a different agent, the patch introduces Client ID mapping. 

For each NS agent partition a range of valid Client IDs is defined in the manifest yaml file. The SPM checks boot time that the ranges don't overlap. The NS agent partitions must make sure that they map incoming client ID's in a way that the output Client ID is always in the range of valid IDs for that NS agent.

If an NS agent has multiple mailboxes, it is possible to assign separate ranges for those mailboxes (the range is associated with the Mailbox IRQ in the manifest yaml).

Please find the patch here: https://review.trustedfirmware.org/c/TF-M/trusted-firmware-m/+/26947

Any questions or comments are welcome!

Best Regards,

Mate