[PATCH v5 0/5] tsm-mr: Unified Measurement Register ABI for TVMs

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

NOTE: This patch series introduces the Measurement Register (MR) ABI, and
is a continuation of the RFC series on the same topic [1].

Introduce the CONFIG_TSM_MEASUREMENTS helper library (tsm-mr) as a
cross-vendor transport schema to allow TVM (TEE VM) guest drivers to export
CC (Confidential Compute) architecture-specific MRs (Measurement Registers)
as sysfs attributes/files. Enable applications to read, write/extend MRs
like regular files, supporting various usages such as configuration
verification (e.g., verify a TVM's configuration against digests stored in
static/immutable MRs like MRCONFIGID on TDX or HOSTDATA on SEV) and runtime
measurements (e.g., extend the measurement of a container image to an RTMR
before running it).

Patches included in this series:

- Patch 1 adds the tsm-mr library to help TVM guest drivers exposing MRs as
  sysfs attributes.
- Patch 2 provides a sample module demonstrating the usage of the new
  tsm-mr library.
- The remaining patches update the TDX guest driver to expose TDX MRs with
  the help of the tsm-mr library.

[1]: https://lore.kernel.org/linux-coco/20241210-tsm-rtmr-v3-0-5997d4dbda73@intel.com/

Signed-off-by: Cedric Xing <cedric.xing@intel.com>
---
Changes in v5:
- tsm-mr: Fix typo in MAINTAINERS.
- tsm-mr-sample: Fix Kconfig dependencies by adding `select VIRT_DRIVERS`.
- Link to v4: https://lore.kernel.org/r/20250414-tdx-rtmr-v4-0-7edfa8d98716@intel.com

Changes in v4:
- tsm-mr: Add details to ABI doc.
- tsm-mr: Add driver-api doc.
- tsm-mr: Add tracepoints.
- tsm-mr: Use the constant string "mr" as the group/directory name for MR
  sysfs attributes.
- x86/tdx: Revise error codes returned by tdx_mcall_* functions.
- tdx-guest: Merge all TDREPORT code paths into a common function.
- Link to v3: https://lore.kernel.org/r/20250407-tdx-rtmr-v3-0-54f17bc65228@intel.com

Changes in v3:
- tsm-mr: Separate measurement support (tsm-mr) from the original tsm
  source code. Modules depending on tsm-mr should `select TSM_MEASUREMENTS`
  in Kconfig. (Dan Williams)
- tsm-mr: Revise tsm-mr APIs to allow callers to decide where to host the
  MR attributes in sysfs.
- tsm-mr: Drop TSM_MR_F_EXTENSIBLE and route all "write" requests to the CC
  guest driver, which decides how to handle writes (e.g., by extending the
  buffer on input to the specified MR).
- tsm-mr: Update the naming pattern for MR attributes from
  MRNAME/HASH/digest to MRNAME:HASH.
- tsm-mr: Drop TSM_MR_MAXBANKS kernel config.
- x86/tdx: Return -EBUSY from tdx_mcall_get_report0 on TDCALL_OPERAND_BUSY
  error.
- tdx-guest: Move MR attributes from /sys/kernel/tsm/tdx/ to
  /sys/class/misc/tdx_guest/ because MR names are architecture-specific, so
  their attributes should reside in an architecture-specific location.
- tdx-guest: Remove hash from `mrconfigid`, `mrowner`, `mrownerconfig`.
- tdx-guest: Remove `servtd_hash`, `report0`, and `reportdata`.
- Link to v2: https://lore.kernel.org/r/20250223-tdx-rtmr-v2-0-f2d85b0a5f94@intel.com

Changes in v2:
- Added TSM_MR_MAXBANKS Kconfig option
- Updated Kconfig dependency for TSM_REPORTS
- Updated comments in include/linux/tsm.h
- Updated drivers/virt/coco/tdx-guest/tdx-guest.c to use `IS_BUILTIN()` for
  determining if static buffer addresses can be converted to GPAs by
  `virt_to_phys()`
- Renamed function `tdx_mcall_rtmr_extend()` -> `tdx_mcall_extend_rtmr()`
- Link to v1: https://lore.kernel.org/r/20250212-tdx-rtmr-v1-0-9795dc49e132@intel.com

---
Cedric Xing (5):
      tsm-mr: Add TVM Measurement Register support
      tsm-mr: Add tsm-mr sample code
      x86/tdx: Add tdx_mcall_extend_rtmr() interface
      x86/tdx: tdx_mcall_get_report0: Return -EBUSY on TDCALL_OPERAND_BUSY error
      virt: tdx-guest: Expose TDX MRs as sysfs attributes

 .../testing/sysfs-devices-virtual-misc-tdx_guest   |  60 +++++
 Documentation/driver-api/coco/index.rst            |  12 +
 .../driver-api/coco/measurement-registers.rst      |  12 +
 Documentation/driver-api/index.rst                 |   1 +
 MAINTAINERS                                        |   6 +-
 arch/x86/coco/tdx/tdx.c                            |  50 +++-
 arch/x86/include/asm/shared/tdx.h                  |   1 +
 arch/x86/include/asm/tdx.h                         |   2 +
 drivers/virt/coco/Kconfig                          |   5 +
 drivers/virt/coco/Makefile                         |   1 +
 drivers/virt/coco/tdx-guest/Kconfig                |   1 +
 drivers/virt/coco/tdx-guest/tdx-guest.c            | 291 +++++++++++++--------
 drivers/virt/coco/tsm-mr.c                         | 247 +++++++++++++++++
 include/linux/tsm-mr.h                             |  94 +++++++
 include/trace/events/tsm_mr.h                      |  80 ++++++
 samples/Kconfig                                    |  11 +
 samples/Makefile                                   |   1 +
 samples/tsm-mr/Makefile                            |   2 +
 samples/tsm-mr/tsm_mr_sample.c                     | 137 ++++++++++
 19 files changed, 904 insertions(+), 110 deletions(-)
---
base-commit: 9c32cda43eb78f78c73aee4aa344b777714e259b
change-id: 20250209-tdx-rtmr-255479667146

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