On Tue, 28 May 2024 at 14:38, Jens Wiklander jens.wiklander@linaro.org wrote:
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 theuser-space daemon tee-supplicant or the RPMB subsystemin the kernel. The value "user" means that the driverwill route the RPMB frames via user space. Conversely,"kernel" means that the frames are routed via the RPMBsubsystem without assistance from tee-supplicant. Itshould be assumed that RPMB frames are routed via userspace if the variable is absent. The primary purposeof this variable is to let systemd know whethertee-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.
Okay but I am still not able to understand the reasoning as to why tee-supplicant can't be started unconditionally. If it's available in the initrd then systemd should be able to launch it unconditionally. Or is there any dependency I am missing for the tee-supplicant to be started? RPMB routing isn't the only service offered by tee-supplcant, so gating it behind that for no real reason isn't making sense to me.
IOW, why do we need to defer starting tee-supplicant until the real rootfs is available?
-Sumit