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2020-10-22drivers/smmstore: Implement SMMSTORE version 2Patrick Rudolph
SMMSTORE version 2 is a complete redesign of the current driver. It is not backwards-compatible with version 1, and only one version can be used at a time. Key features: * Uses a fixed communication buffer instead of writing to arbitrary memory addresses provided by untrusted ring0 code. * Gives the caller full control over the used data format. * Splits the store into smaller chunks to allow fault tolerant updates. * Doesn't provide feedback about the actual read/written bytes, just returns error or success in registers. * Returns an error if the requested operation would overflow the communication buffer. Separate the SMMSTORE into 64 KiB blocks that can individually be read/written/erased. To be used by payloads that implement a FaultTolerant Variable store like TianoCore. The implementation has been tested against EDK2 master. An example EDK2 implementation can be found here: https://github.com/9elements/edk2-1/commit/eb1127744a3a5d5c8ac4e8eb76f07e79c736dbe2 Change-Id: I25e49d184135710f3e6dd1ad3bed95de950fe057 Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com> Signed-off-by: Christian Walter <christian.walter@9elements.com> Reviewed-on: https://review.coreboot.org/c/coreboot/+/40520 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Michał Żygowski <michal.zygowski@3mdeb.com> Reviewed-by: Matt DeVillier <matt.devillier@gmail.com>