[PATCH RFC v3 0/2] tsm: Unified Measurement Register ABI for TVMs

[Cedric Xing <cedric.xing@intel.com>]

NOTE: This patch series introduces the Measurement Register (MR) ABI, and
is largely a continuation of Samuel Ortiz’s previous work on the RTMR ABI
[1].

This patch series adds a unified interface to TSM core for confidential
computing (CC) guest drivers to provide access to measurement registers
(MRs), which are essential for relying parties (RPs) to verify the
integrity of the computing environment. The interface is structured around
`struct tsm_measurement`, which holds an array of `struct
tsm_measurement_register` and includes operations for reading and updating
MRs.

Each `struct tsm_measurement_register` features a `mr_flags` member that
indicates the MR's properties, such as *Readable* (`TSM_MR_F_R`),
*Extensible* (`TSM_MR_F_X`), etc. Please refer to Patch 1 in this series
for more details. Patch 2 adds a sample module to demonstrate how to define
and implement MRs in a CC guest driver.

MRs are made accessible to applications through a directory tree (rooted at
`/sys/kernel/tsm`). An MR could be presented as either a file containing
its value, or a directory containing the file `digest` under a subdirectory
of the same name as the hash algorithm. By default, an MR will be presented
as a directory unless `TSM_MR_F_F` is set in `mr_flags`.

[1]: https://patchwork.kernel.org/project/linux-integrity/cover/20240128212532.2754325-1-sameo@rivosinc.com/

Signed-off-by: Cedric Xing <cedric.xing@intel.com>
---
Changes in v3:
- Added *Crypto Agility* support, see patch 1
- Fixed style issues in both commit messages and code
- Fixed incorrect assignment of files to commits
- Link to v2: https://lore.kernel.org/r/20241031-tsm-rtmr-v2-0-1a6762795911@intel.com

Changes in v2:
- Separated TSM MR code in a new file: `tsm-mr.c`.
- Removed RTMR event logging due to the lack of agreement on the log
  format.
- Default presentation of each MR as a directory, with the option to
  request an
  MR as a file using `TSM_MR_F_F`.
- Reduced verbosity: Renamed `struct tsm_measurement_provider` to `struct
  tsm_measurement`, and `tsm_(un)register_measurement_provider` to
  `tsm_(un)register_measurement`.
- Added `MODULE_DESCRIPTION` for measurement-sample.
- Fixed several compiler warnings on 32-bit builds.
- Link to v1: https://lore.kernel.org/r/20240907-tsm-rtmr-v1-0-12fc4d43d4e7@intel.com

---
Cedric Xing (2):
      tsm: Add TVM Measurement Register Support
      tsm: Add TVM Measurement Sample Code

 MAINTAINERS                             |   3 +-
 drivers/virt/coco/Kconfig               |   3 +-
 drivers/virt/coco/Makefile              |   2 +
 drivers/virt/coco/{tsm.c => tsm-core.c} |   6 +-
 drivers/virt/coco/tsm-mr.c              | 376 ++++++++++++++++++++++++++++++++
 include/linux/tsm.h                     |  64 ++++++
 samples/Kconfig                         |   4 +
 samples/Makefile                        |   1 +
 samples/tsm/Makefile                    |   2 +
 samples/tsm/measurement-example.c       | 113 ++++++++++
 10 files changed, 571 insertions(+), 3 deletions(-)
---
base-commit: fac04efc5c793dccbd07e2d59af9f90b7fc0dca4
change-id: 20240904-tsm-rtmr-7a45859d2a96

Best regards,
-- 
Cedric Xing <cedric.xing@intel.com>