[PATCH v1 0/2] efi/tpm: Preserve event log without changing x86 E820

[Jasmeet (Jazz) Bhatia]

The EFI stub currently allocates the TPM event log as
EFI_ACPI_RECLAIM_MEMORY. On x86, this becomes an ACPI data entry
in the E820 map.

On a Framework Laptop 16 (AMD Ryzen AI 300 Series), the EFI allocator
can place this allocation at different physical addresses across boots.
Since x86 hibernation validates architecture-specific data from
the firmware E820 map, this causes an otherwise valid hibernation image
to be rejected on resume with the following error:

  Hibernate inconsistent memory map detected!
  PM: hibernation: Image mismatch: architecture specific data

Allocating the event log as EFI_LOADER_DATA avoids changing the E820
map, but doing that alone would regress the kexec corruption issue fixed
by commit 77d48d39e991 ("efistub/tpm: Use ACPI reclaim memory for event
log to avoid corruption").

This patch series instead installs the Linux EFI memreserve table on the
x86 stub path and then uses efi_mem_reserve_persistent() to preserve the
TPM event log across kexec while keeping the allocation as
EFI_LOADER_DATA.

The series was also backported to Linux 7.2 for validation on the
affected system.

Results:

- stock 7.2:
  TPM event log allocation changes the E820 map across boots;
  hibernation resume fails

- EFI_LOADER_DATA-only diagnostic build:
  E820 map remains stable;
  hibernation resume succeeds

- this series:
  TPM range is persistently reserved;
  hibernation resume succeeds with the normal device drivers;
  kexec_file_load() succeeds with the TPM range preserved;
  kexec_load() succeeds with the TPM range preserved

For kexec_file_load(), the event log had the same size and SHA256 digest
before and after kexec. For kexec_load(), the before and after event log
files compared byte-for-byte identical.

The original report and investigation are here:
  https://lore.kernel.org/all/DL3MNWW4VEBR.K3K6A92WMHUY@xxxxxxxxx/

Patch 1 makes the existing EFI memreserve table installer available to
the x86 EFI stub path.

Patch 2 switches the TPM event log allocation back to EFI_LOADER_DATA
and persistently reserves it after the normal TPM event log reservation
has succeeded.

Jasmeet (Jazz) Bhatia (2):
  efi/libstub: Install memreserve table on x86
  efi/tpm: Persistently reserve the TPM event log

 .../firmware/efi/libstub/efi-stub-helper.c    | 23 ++++++++++++++++
 drivers/firmware/efi/libstub/efi-stub.c       | 23 ----------------
 drivers/firmware/efi/libstub/efistub.h        |  1 +
 drivers/firmware/efi/libstub/tpm.c            |  2 +-
 drivers/firmware/efi/libstub/x86-stub.c       |  2 ++
 drivers/firmware/efi/tpm.c                    | 27 +++++++++++++++++++
 6 files changed, 54 insertions(+), 24 deletions(-)


base-commit: 786262be6048deab760f68c8acc2c85607165894
-- 
2.55.0