[PATCH v3 00/10] arm64: FF-A runtime transport for EFI variables

[Heinrich Schuchardt]

On 6/27/26 16:44, Harsimran Singh Tungal wrote:
> Hi all,
> 
> This series adds FF-A runtime transport support so EFI variable runtime
> services can communicate with the secure world after ExitBootServices().
> It also extends tests, docs, and board configs to validate the runtime
> path and keep boot-time behavior aligned with the runtime flow.

Hello Harsiman,

Unfortunately this cover-letter lacks some background information needed 
for reviewing the patch series.

Why is this new transport needed? We already have a transport for EFI 
variables to the secure world via OP-TEE (see CONFIG_EFI_MM_COMM_TEE).

Where is the EFI variables specific FF-A message protocol specified?

Is there a Linux driver that can communicate via this message protocol?

How can the transport be tested with QEMU and Linux?

Best regards

Heinrich

> 
> Changes in this series:
> - Add EFI runtime-safe memset helper and FF-A runtime transport support.
> - Implement FF-A runtime communication in the EFI variable TEE backend.
> - Enable EFI runtime variable operations over the FF-A transport.
> - Add sandbox runtime transport tests.
> - Extend EFI selftests for runtime variables and bootefi selftest config.
> - Document the FF-A runtime transport and selftest behavior.
> 
> Changes in v3:
> 
> Address Simon Glass's review comments:
> - Move FF-A ExitBootServices event registration to the end of probe and
>    clean up RX/TX buffer handling on failure.
> - Rename FF-A runtime-context helpers to the ffa_runtime_context_* form.
> - Rework FF-A/MM cache maintenance to cover only rounded request and
>    response ranges.
> - Add SetVirtualAddressMap handling for the FF-A shared buffer.
> - Document FF-A shared-buffer ownership and alignment assumptions.
> - Add EFIAPI to the TEE runtime GetVariable and GetNextVariableName
>    entry points.
> - Tighten sandbox FF-A runtime tests and reset runtime state between
>    test cases.
> - Update FF-A and bootefi documentation for the runtime transport and
>    split runtime-variable selftests.
> - Rework commit messages to drop redundant information.
> 
> Address Ilias Apalodimas's review comments:
> - Keep efi_var_common.c unchanged and drop commit 6 from v2 patchset.
> - Rename the TEE/FF-A runtime handlers to the *_int_runtime form.
> - Remove log_*() calls from __efi_runtime FF-A/MM communication paths.
> 
> Other:
> - Fix FF-A memory-share sender_id to use the runtime private endpoint
>    ID after rebasing.
> - Fix the expected QueryVariableInfo() return status for the
>    TEE-backed runtime selftest path.
> 
> 
> Changes in v2:
> 
> Address Simon Glass's review comments:
> - Fix efi_memset_runtime() style, declaration, and byte cast
> - Tighten the FF-A runtime context failure path, clean up arm-ffa-runtime.c
>    style issues, and move ExitBootServices event registration earlier in probe
> - Add shared-buffer bounds/alignment checks, and tightening comments/kernel-doc
> - Document the FF-A shared buffer cacheline-alignment requirement and add
>    BUILD_BUG_ON() checks for the address
> - Cache attributes before the shared buffer is reused, moving the read-only
>    check earlier, and split the u16_strsize() related change in separate patch
> - Reword commit messages for the runtime helper relocation
> - Rework the non-volatile runtime variable selftest into setup/verify phases
> - Extend the sandbox FF-A runtime tests with no-context coverage,
>    runtime-context reset, and separate errno-mapping coverage
> - Refresh the FF-A runtime transport and bootefi documentation
> - Drop patch 12 in v1, as ffa_mm_communicate handles both runtime and
>    boottime capabilities in v2
> - Squash patch 8 and patch 9 from v1
> 
> Address Ilias Apalodimas's review comments:
> - Reuse common MM SP error mapping for boot and runtime paths
> - Rename runtime-phase tracking to reflect the ExitBootServices transition
> - Collapse duplicated boot-time and runtime MM communication helpers into common
>    implementations
> - Keep the arm64 cache-maintenance path runtime-safe
> - Move FF-A shared-buffer runtime memory-map registration to the end of
>    variable-service initialization
> 
> Link to v2: https://lore.kernel.org/u-boot/20260514124924.1804332-1-harsimransingh.tungal@arm.com/
> Link to v1: https://lore.kernel.org/u-boot/20260424173151.371134-1-harsimransingh.tungal@arm.com/
> 
> Harsimran Singh Tungal (10):
>    efi_loader: add runtime memset helper
>    arm-ffa: add FF-A bus runtime support
>    efi_loader: add FF-A runtime support in EFI variable TEE driver
>    efi_loader: enable EFI runtime SetVariable()/GetVariable() using FF-A
>      transport
>    charset: mark u16_strsize() as __efi_runtime
>    corstone1000: enable bootefi selftest
>    efi: selftest: add runtime variable tests with non-volatile storage
>    test: dm: add sandbox FF-A runtime transport tests
>    doc: arm64: document FF-A runtime path for EFI variables
>    doc: bootefi: note two-phase runtime variables selftest
> 
>   arch/arm/cpu/armv8/cache.S                    |   8 +
>   arch/arm/cpu/armv8/cache_v8.c                 |  13 +-
>   arch/sandbox/include/asm/sandbox_arm_ffa.h    |  16 +-
>   configs/corstone1000_defconfig                |   3 +
>   doc/arch/arm64.ffa.rst                        |  88 ++-
>   doc/usage/cmd/armffa.rst                      |  11 +
>   doc/usage/cmd/bootefi.rst                     |  31 +
>   drivers/firmware/arm-ffa/Kconfig              |  11 +
>   drivers/firmware/arm-ffa/Makefile             |   4 +-
>   drivers/firmware/arm-ffa/arm-ffa-runtime.c    | 294 +++++++
>   drivers/firmware/arm-ffa/arm-ffa-uclass.c     | 114 +--
>   drivers/firmware/arm-ffa/arm-ffa.c            |  16 +-
>   drivers/firmware/arm-ffa/ffa-emul-uclass.c    |  49 +-
>   include/arm_ffa.h                             |  16 +-
>   include/arm_ffa_priv.h                        |  22 +-
>   include/arm_ffa_runtime.h                     | 191 +++++
>   include/efi_loader.h                          |   3 +
>   lib/charset.c                                 |   2 +-
>   lib/efi_loader/Kconfig                        |   4 +
>   lib/efi_loader/efi_runtime.c                  |  20 +
>   lib/efi_loader/efi_variable_tee.c             | 726 +++++++++++++++---
>   .../efi_selftest_variables_runtime.c          | 715 +++++++++++------
>   test/dm/Makefile                              |   3 +-
>   test/dm/ffa.c                                 |   6 +-
>   test/dm/ffa_runtime.c                         | 123 +++
>   25 files changed, 1997 insertions(+), 492 deletions(-)
>   create mode 100644 drivers/firmware/arm-ffa/arm-ffa-runtime.c
>   create mode 100644 include/arm_ffa_runtime.h
>   create mode 100644 test/dm/ffa_runtime.c
>