Messages in this thread | | | From | Ilias Apalodimas <> | Date | Wed, 24 May 2023 11:00:21 +0300 | Subject | Re: [PATCH v4 0/3] introduce tee-based EFI Runtime Variable Service |
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Hi Sumit,
On Wed, 24 May 2023 at 10:56, Sumit Garg <sumit.garg@linaro.org> wrote: > > On Tue, 23 May 2023 at 14:36, Masahisa Kojima > <masahisa.kojima@linaro.org> wrote: > > > > 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 > > I don't have detailed insights into how EFI spec mandates StandaloneMM > should be implemented. But utilizing OP-TEE as the underlying > transport here looks fine to me. FWIW, > > For the series: > Acked-by: Sumit Garg <sumit.garg@linaro.org>
Thanks!
FWIW the PI spec describes some of the functionality and how that should be accessed. There's a EFI_MM_COMMUNICATION_PROTOCOL which is not used here. Instead the entry point is via an SMC to op-tee and the payload adheres to what the PI spec describes in its EFI_MM_COMMUNICATE_HEADER
Regards /Ilias > > -Sumit > > > > > 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 > > > > -- > > 2.30.2 > >
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