linux-kernel - [PATCH v4 0/7] KVM: selftests: access_tracking_perf

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Message-ID: <20250508184649.2576210-1-jthoughton@google.com>
Date: Thu,  8 May 2025 18:46:41 +0000
From: James Houghton <jthoughton@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, kvm@...r.kernel.org
Cc: Maxim Levitsky <mlevitsk@...hat.com>, Axel Rasmussen <axelrasmussen@...gle.com>, 
	Tejun Heo <tj@...nel.org>, Johannes Weiner <hannes@...xchg.org>, mkoutny@...e.com, 
	Yosry Ahmed <yosry.ahmed@...ux.dev>, Yu Zhao <yuzhao@...gle.com>, 
	David Matlack <dmatlack@...gle.com>, James Houghton <jthoughton@...gle.com>, cgroups@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: [PATCH v4 0/7] KVM: selftests: access_tracking_perf_test fixes for
 NUMA balancing and MGLRU

This series fixes some issues with access_tracking_perf_test when MGLRU
or NUMA balancing are in use.

With MGLRU, touching a page doesn't necessarily clear the Idle flag.
This has come up in the past, and the recommendation was to use MGLRU
generation numbers[1], which this series does.

With NUMA balancing, pages are temporarily mapped as PROT_NONE, so the
SPTEs will be zapped, losing the Accessed bits. The fix here is, in the
event we have lost access information to print a warning and continue
with the test, just like what we do if the test is running a nested VM.

A flag is added for the user to specify if they wish for the test to
always enforce or always skip this check.

Based on kvm/next.

Changelog:

v3[4] -> v4:
- Multiple fixes to access_tracking_perf_test:
  1. Fix for software-managed A/D-bit configs.
  2. Fix for expected number of pages when guest page size is >
     PAGE_SIZE.
  3. Properly check youngest generation when looking for pages.
- Do an initial aging pass for MGLRU. This allows us to check that pages
  move back to the youngest generation after the first access pass.
- Add controller-root location logic in the cgroup utils, and use this
  to make the test work for cgroup-v1 (thanks Sean!).
- Some cleanup for access_tracking_perf_test code, comments, warning
  messages, and the commit message (thanks Sean!).

v2[3] -> v3:
- Applied David's directory fix on patch 3.
- Added SoB-by, R-by (patch 2, missed in v2), and A-by.

v1[2] -> v2:
- Re-add clone3_selftests.h for cgroup selftests (thanks Michal!)
- Some comment fixes, patches 2 and 5 (thanks Maxim!).

[1]: https://lore.kernel.org/all/CAOUHufZeADNp_y=Ng+acmMMgnTR=ZGFZ7z-m6O47O=CmJauWjw@mail.gmail.com/
[2]: https://lore.kernel.org/kvm/20250327012350.1135621-1-jthoughton@google.com/
[3]: https://lore.kernel.org/kvm/20250331213025.3602082-1-jthoughton@google.com/
[4]: https://lore.kernel.org/kvm/20250414200929.3098202-1-jthoughton@google.com/

James Houghton (3):
  cgroup: selftests: Move cgroup_util into its own library
  KVM: selftests: Build and link selftests/cgroup/lib into KVM selftests
  KVM: selftests: access_tracking_perf_test: Use MGLRU for access
    tracking

Maxim Levitsky (1):
  KVM: selftests: access_tracking_perf_test: Add option to skip the
    sanity check

Sean Christopherson (3):
  KVM: selftests: Extract guts of THP accessor to standalone sysfs
    helpers
  cgroup: selftests: Move memcontrol specific helpers out of common
    cgroup_util.c
  cgroup: selftests: Add API to find root of specific controller

 tools/testing/selftests/cgroup/Makefile       |  21 +-
 .../selftests/cgroup/{ => lib}/cgroup_util.c  | 118 ++----
 .../cgroup/{ => lib/include}/cgroup_util.h    |  13 +-
 .../testing/selftests/cgroup/lib/libcgroup.mk |  19 +
 .../selftests/cgroup/test_memcontrol.c        |  78 ++++
 tools/testing/selftests/kvm/Makefile.kvm      |   4 +-
 .../selftests/kvm/access_tracking_perf_test.c | 281 +++++++++++--
 .../selftests/kvm/include/lru_gen_util.h      |  51 +++
 .../testing/selftests/kvm/include/test_util.h |   1 +
 .../testing/selftests/kvm/lib/lru_gen_util.c  | 386 ++++++++++++++++++
 tools/testing/selftests/kvm/lib/test_util.c   |  42 +-
 11 files changed, 865 insertions(+), 149 deletions(-)
 rename tools/testing/selftests/cgroup/{ => lib}/cgroup_util.c (88%)
 rename tools/testing/selftests/cgroup/{ => lib/include}/cgroup_util.h (91%)
 create mode 100644 tools/testing/selftests/cgroup/lib/libcgroup.mk
 create mode 100644 tools/testing/selftests/kvm/include/lru_gen_util.h
 create mode 100644 tools/testing/selftests/kvm/lib/lru_gen_util.c


base-commit: 45eb29140e68ffe8e93a5471006858a018480a45
-- 
2.49.0.1015.ga840276032-goog