This series introduces TEE system sessions for TEE service sessions that require TEE to provision resources to prevent deadlock when clients call the TEE.
This deadlock situation can happen when a TEE service is used by low level system resources as for example when Linux kernel uses SCMI service embedded in TEE for clock, reset, regulator, etc... controls. This case is detailled in patch 2/4:
This feature is needed to prevent a system deadlock when several TEE client applications invoke TEE, consuming all TEE thread contexts available in the secure world. The deadlock can happen in the OP-TEE driver for example if all these TEE threads issue an RPC call from TEE to Linux OS to access an eMMC RPMB partition (TEE secure storage) which device clock or regulator controller is accessed through an OP-TEE SCMI services. In that case, Linux SCMI driver must reach OP-TEE SCMI service without waiting until one of the consumed TEE threads is freed.
Etienne Carriere (4): tee: optee: system call property tee: system session tee: optee: support tracking system threads firmware: arm_scmi: optee: use optee system invocation
drivers/firmware/arm_scmi/optee.c | 4 + drivers/tee/optee/call.c | 152 +++++++++++++++++++++++++++--- drivers/tee/optee/core.c | 5 +- drivers/tee/optee/ffa_abi.c | 13 +-- drivers/tee/optee/optee_private.h | 33 ++++++- drivers/tee/optee/smc_abi.c | 31 ++++-- drivers/tee/tee_core.c | 8 ++ include/linux/tee_drv.h | 16 ++++ 8 files changed, 227 insertions(+), 35 deletions(-)