[PATCH v5 0/5] selftests/resctrl: Add MBM and MBA test support for AMD

[Swapnil Sapkal <swapnil.sapkal@amd.com>]

The MBM (Memory Bandwidth Monitoring) and MBA (Memory Bandwidth
Allocation) resctrl selftests validate the bandwidth numbers reported by
resctrl against the memory controller performance counters. Today this
only works on Intel, where the counters are the iMC (Integrated Memory
Controller) PMUs and the tests are gated behind an ARCH_INTEL vendor
check.

This series teaches the tests about the AMD UMC (Unified Memory
Controller) PMUs and enables MBM and MBA on AMD.

The work is done in a few steps:

  1. Rename the Intel specific imc/IMC identifiers to the generic
     mc/MC so the code can serve both vendors.

  2. Detect the vendor and select the memory controller PMU sysfs name
     accordingly, keeping the rest of the code generic.

  3. Add the AMD UMC support. Unlike Intel, the UMC PMU does not expose
     the CAS command events via sysfs, so the read event is programmed
     directly (EventCode 0x0a, umask 0x1). All vendor detection is
     contained in enumerate_mcs() and dispatched to per-vendor routines.
     On AMD each UMC is a per-NUMA-node PMU, so only the UMCs local to
     the benchmark CPU are opened; remote-node UMCs would otherwise fail
     perf_event_open() with -ENODEV.

  4. Sweep the AMD MBA schemata using absolute bandwidth values (4 GB/s
     to 40 GB/s) instead of the Intel style percentages (10% to 100%).

  5. Extend the vendor_specific gate of the tests to Intel and AMD so
     they run on AMD as well. The gate is kept (rather than removed)
     so vendors that enumerate_mcs() does not know about are skipped
     instead of reported as a failure.

Testing
-------
Tested on AMD Zen5 (single-numa and multi-NUMA); MBM and MBA tests
pass on both.

This series applies on top of the kselftest tree's "next" branch.

v4: https://lore.kernel.org/all/20260810184806.1089507-1-swapnil.sapkal@amd.com/

Changes since v4:
- Rebased onto the kselftest "next" branch. The memory bandwidth
  counters there are now kept in a dynamically managed linked list
  (instead of a fixed array), so the whole series was reworked on top of
  that infrastructure. The enumeration routine is now enumerate_mcs()
  and the AMD path allocates and links each UMC counter.
- No other functional changes relative to v4.

Babu Moger (4):
  selftests/resctrl: Rename variables and functions to generic names
  selftests/resctrl: Detect vendor to select memory controller sysfs
    name
  selftests/resctrl: Add support for MBM and MBA tests on AMD
  selftests/resctrl: Enable MBM and MBA tests on AMD

Swapnil Sapkal (1):
  selftests/resctrl: Use bandwidth values for AMD MBA schemata

 tools/testing/selftests/resctrl/mba_test.c    | 107 +++--
 tools/testing/selftests/resctrl/mbm_test.c    |  26 +-
 tools/testing/selftests/resctrl/resctrl.h     |   6 +-
 tools/testing/selftests/resctrl/resctrl_val.c | 384 +++++++++++-------
 4 files changed, 334 insertions(+), 189 deletions(-)

-- 
2.43.0