⚠️ The code is based on: https://gitlab.com/riseproject/riscv-optee/optee_os/-/tree/dev-optee-mpxy

Commit ID: 75df9ba41a404aec897399ead0ff0aebcbff48ca

  • mpxy_opteed_channel_init()

    • Check if MPXY extension is supported by OpenSBI.
    • Extract MPXY channel ID from DT:

      • compatible = “riscv,sbi-mpxy-opteed";

      • riscv,sbi-mpxy-channel-id ← Defines MPXY channel ID.

        • Save MPXY channel ID to mpxy_opteed_ctx.channel_id.

      • opensbi-domain-instance ← Defines the OpenSBI domain used by OP-TEE (not used by OP-TEE).

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        chosen {
    opensbi-domains {
        trusted-domain {
        compatible = "opensbi,domain,instance";
        regions = <0x04 0x3f>;
        possible-harts = <0x03 0x01>;
        next-addr = <0x00 0xf1000000>;
        next-mode = <0x01>;
        phandle = <0x02>;
    };
};

sbi-mpxy-opteed {
    opensbi-domain-instance = <0x02>;
    riscv,sbi-mpxy-channel-id = <0x02>;
    compatible = "riscv,sbi-mpxy-opteed";
};

  • sbi_mpxy_setup_shmem()

    • Allocates 4KB MPXY shared memory (4KB aligned).
    • Call sbi_mpxy_set_shmem SBI call to set up the allocated MPXY shared memory for the current core. This will invoke OpenSBI’s sbi_mpxy_set_shmem() to save the shared memory address and size into current hart tdomain’s mpxy_state.

  • thread_return_to_udomain_by_mpxy()

    • Save the args (arg0, arg1, arg2, arg3, arg4) to TX buffer (struct optee_msg_payload).
    • Issue SBI call: Send Message with Response (FID #4) with message ID: OPTEED_MSG_COMPLETE (0x2).

  • sbi_mpxy_send_message_withresp()

    • Send Message with Response (FID #4)
      1. Copy the message from TX buffer to the shared memory.
      2. Issue the SBI call. Switch to OpenSBI and jump to: sbi_ecall_mpxy_handler()
      3. If ret.error is success:
        1. Copy the response message from the shared memory to the RX buffer.