[PATCH 0/4] selftests/resctrl: MBA schemata ABI selftests for MPAM platforms

[Richard Cheng <icheng@nvidia.com>]

The MPAM MBA enablement carried in this tree exposes memory-bandwidth
allocation through the resctrl "MB" schemata, but none of it is covered
by the in-tree resctrl selftests: the existing mba_test/mbm_test are
ARCH_INTEL-gated throughput tests that validate against the Intel iMC
PMU and map domains via L3 cache ids, so they skip (and cannot work) on
aarch64/MPAM, where MB domains are NUMA proximity ids. Any regression
in the MB control plane currently ships unnoticed.

Add four deterministic, workload-free ABI tests in a shared
MBA_SCHEMATA group, one resctrl_test entry each:

  1. MBA_SCHEMATA_INFO    - sane control contract (schema_format, gran,
                            min_bandwidth, num_closids) and default
                            schemata at 100% on every domain
  2. MBA_SCHEMATA_RW      - percentages take effect and read back
                            exactly, per domain, including restore
  3. MBA_SCHEMATA_INVAL   - out-of-range/malformed/bad-domain writes
                            are rejected with the documented
                            last_cmd_status diagnostics
  4. MBA_SCHEMATA_ISOLATE - two groups keep independent caps; the
                            default group is never perturbed

All cases are feature-gated (schema_format == percentage) and skip
cleanly elsewhere; no workload or measurement is involved, so they are
CI-safe and flake-free. The Intel tests are left untouched. The tests
are written upstream-shaped for eventual submission.

This series applies on top of the 26.04_linux-nvidia.glue.others.
cpu_less.hardlimit branch of
https://github.com/fyu1/NV-Kernels.fenghuay.baseos

Tested on an NVIDIA Grace (Vera) system with MPAM MBA enabled (two MB
domains): sudo ./resctrl_tests -t MBA_SCHEMATA -> 4/4 pass.

The newly added test file fires a warning when using checkpatch.pl .

Richard Cheng (4):
  selftests/resctrl: Add MBA schemata info selftest
  selftests/resctrl: Add MBA schemata write/read-back selftest
  selftests/resctrl: Add MBA schemata invalid-write selftest
  selftests/resctrl: Add MBA schemata per-group isolation selftest

 .../selftests/resctrl/mba_schemata_test.c     | 521 ++++++++++++++++++
 tools/testing/selftests/resctrl/resctrl.h     |   7 +
 .../testing/selftests/resctrl/resctrl_tests.c |   4 +
 tools/testing/selftests/resctrl/resctrlfs.c   | 157 ++++++
 4 files changed, 689 insertions(+)
 create mode 100644 tools/testing/selftests/resctrl/mba_schemata_test.c


base-commit: 475f355d0408698d9f632ba3b9a5dfb1f91e928b
-- 
2.43.0