tsm-mr: Add TVM Measurement Register support

Introduce new TSM Measurement helper library (tsm-mr) for TVM guest drivers
to expose MRs (Measurement Registers) as sysfs attributes, with Crypto
Agility support.

Add the following new APIs (see include/linux/tsm-mr.h for details):

- tsm_mr_create_attribute_group(): Take on input a `struct
  tsm_measurements` instance, which includes one `struct
  tsm_measurement_register` per MR with properties like `TSM_MR_F_READABLE`
  and `TSM_MR_F_WRITABLE`, to determine the supported operations and create
  the sysfs attributes accordingly. On success, return a `struct
  attribute_group` instance that will typically be included by the guest
  driver into `miscdevice.groups` before calling misc_register().

- tsm_mr_free_attribute_group(): Free the memory allocated to the attrubute
  group returned by tsm_mr_create_attribute_group().

tsm_mr_create_attribute_group() creates one attribute for each MR, with
names following this pattern:

        MRNAME[:HASH]

- MRNAME - Placeholder for the MR name, as specified by
  `tsm_measurement_register.mr_name`.
- :HASH - Optional suffix indicating the hash algorithm associated with
  this MR, as specified by `tsm_measurement_register.mr_hash`.

Support Crypto Agility by allowing multiple definitions of the same MR
(i.e., with the same `mr_name`) with distinct HASH algorithms.

NOTE: Crypto Agility, introduced in TPM 2.0, allows new hash algorithms to
be introduced without breaking compatibility with applications using older
algorithms. CC architectures may face the same challenge in the future,
needing new hashes for security while retaining compatibility with older
hashes, hence the need for Crypto Agility.

Signed-off-by: Cedric Xing <cedric.xing@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Dionna Amalie Glaze <dionnaglaze@google.com>
[djbw: fixup bin_attr const conflict]
Link: https://patch.msgid.link/20250509020739.882913-1-dan.j.williams@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

0 files changed, 0 insertions, 0 deletions