Re: [PATCH v7 4/4] optee: probe RPMB device using RPMB subsystem

Hi Sumit,

On Mon, May 27, 2024 at 4:38 PM Sumit Garg sumit.garg@linaro.org wrote:

On Mon, 27 May 2024 at 17:44, Jens Wiklander jens.wiklander@linaro.org wrote:

...

Adds support in the OP-TEE drivers (both SMC and FF-A ABIs) to probe and use an RPMB device via the RPMB subsystem instead of passing the RPMB frames via tee-supplicant in user space. A fallback mechanism is kept to route RPMB frames via tee-supplicant if the RPMB subsystem isn't available.

The OP-TEE RPC ABI is extended to support iterating over all RPMB devices until one is found with the expected RPMB key already programmed.

Signed-off-by: Jens Wiklander jens.wiklander@linaro.org Tested-by: Manuel Traut manut@mecka.net

---

Documentation/ABI/testing/sysfs-class-tee | 15 ++ MAINTAINERS | 1 + drivers/tee/optee/core.c | 96 +++++++++++- drivers/tee/optee/device.c | 7 + drivers/tee/optee/ffa_abi.c | 14 ++ drivers/tee/optee/optee_ffa.h | 2 + drivers/tee/optee/optee_private.h | 26 +++- drivers/tee/optee/optee_rpc_cmd.h | 35 +++++ drivers/tee/optee/optee_smc.h | 2 + drivers/tee/optee/rpc.c | 177 ++++++++++++++++++++++ drivers/tee/optee/smc_abi.c | 14 ++ 11 files changed, 387 insertions(+), 2 deletions(-) create mode 100644 Documentation/ABI/testing/sysfs-class-tee

diff --git a/Documentation/ABI/testing/sysfs-class-tee b/Documentation/ABI/testing/sysfs-class-tee new file mode 100644 index 000000000000..c9144d16003e --- /dev/null +++ b/Documentation/ABI/testing/sysfs-class-tee @@ -0,0 +1,15 @@ +What: /sys/class/tee/tee{,priv}X/rpmb_routing_model +Date: May 2024 +KernelVersion: 6.10 +Contact: op-tee@lists.trustedfirmware.org +Description:

•           RPMB frames can be routed to the RPMB device via the
  

•           user-space daemon tee-supplicant or the RPMB subsystem
  

•           in the kernel. The value "user" means that the driver
  

•           will route the RPMB frames via user space. Conversely,
  

•           "kernel" means that the frames are routed via the RPMB
  

•           subsystem without assistance from tee-supplicant. It
  

•           should be assumed that RPMB frames are routed via user
  

•           space if the variable is absent. The primary purpose
  

•           of this variable is to let systemd know whether
  

•           tee-supplicant is needed in the early boot with initramfs.
  

Why do we need this if we already have [1] [2]? AFAICS, whichever devices like fTPM etc. systemd depends upon, it can be easily known via existing sysfs property.

[1] https://docs.kernel.org/admin-guide/abi-testing.html?highlight=optee#abi-sys... [2] Documentation/ABI/testing/sysfs-bus-optee-devices

The dependency is reversed. A TA depending on tee-supplicant will not be loaded until tee-supplicant is ready. rpmb_routing_model is used as one of the inputs to determine if tee-supplicant must be started early or if it can wait until the real rootfs is available.

Thanks, Jens