This series introduces the tee based EFI Runtime Variable Service.
The eMMC device is typically owned by the non-secure world(linux in this case). There is an existing solution utilizing eMMC RPMB partition for EFI Variables, it is implemented by interacting with OP-TEE, StandaloneMM(as EFI Variable Service Pseudo TA), eMMC driver and tee-supplicant. The last piece is the tee-based variable access driver to interact with OP-TEE and StandaloneMM.
Changelog: v3 -> v4: - replace the reference from EDK2 to PI Specification - remove EDK2 source code reference comments - prepare nonblocking variant of set_variable, it just returns EFI_UNSUPPORTED - remove redundant buffer size check - argument name change in mm_communicate - function interface changes in setup_mm_hdr to remove (void **) cast
v2 -> v3: - add CONFIG_EFI dependency to TEE_STMM_EFI - add missing return code check for tee_client_invoke_func() - directly call efivars_register/unregister from tee_stmm_efi.c
rfc v1 -> v2: - split patch into three patches, one for drivers/tee, one for include/linux/efi.h, and one for the driver/firmware/efi/stmm - context/session management into probe() and remove() same as other tee client driver - StMM variable driver is moved from driver/tee/optee to driver/firmware/efi - use "tee" prefix instead of "optee" in driver/firmware/efi/stmm/tee_stmm_efi.c, this file does not contain op-tee specific code, abstracted by tee layer and StMM variable driver will work on other tee implementation. - PTA_STMM_CMD_COMMUNICATE -> PTA_STMM_CMD_COMMUNICATE - implement query_variable_store() but currently not used - no use of TEEC_SUCCESS, it is defined in driver/tee/optee/optee_private.h. Other tee client drivers use 0 instead of using TEEC_SUCCESS - remove TEEC_ERROR_EXCESS_DATA status, it is referred just to output error message
Masahisa Kojima (3): efi: expose efivar generic ops register function efi: Add EFI_ACCESS_DENIED status code efi: Add tee-based EFI variable driver
drivers/firmware/efi/Kconfig | 15 + drivers/firmware/efi/Makefile | 1 + drivers/firmware/efi/efi.c | 12 + drivers/firmware/efi/stmm/mm_communication.h | 236 +++++++ drivers/firmware/efi/stmm/tee_stmm_efi.c | 637 +++++++++++++++++++ include/linux/efi.h | 4 + 6 files changed, 905 insertions(+) create mode 100644 drivers/firmware/efi/stmm/mm_communication.h create mode 100644 drivers/firmware/efi/stmm/tee_stmm_efi.c