[PATCH 0/3] cgroup/misc: Add hwcap masks to the misc controller

This patch series introduces a mechanism to mask hardware capabilities
(AT_HWCAP) reported to user-space processes via the misc cgroup
controller.

To support C/R operations (snapshots, live migration) in heterogeneous
clusters, we must ensure that processes utilize CPU features available
on all potential target nodes. To solve this, we need to advertise a
common feature set across the cluster. This patchset allows users to
configure a mask for AT_HWCAP, AT_HWCAP2. This ensures that applications
within a container only detect and use features guaranteed to be
available on all potential target hosts.

The first patch adds the mask interface to the misc cgroup controller,
allowing users to set masks for AT_HWCAP, AT_HWCAP2...

The second patch adds a selftest to verify the functionality of the new
interface, ensuring masks are applied and inherited correctly.

The third patch updates the documentation.

Cc: Kees Cook <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: "Michal Koutný" <[email protected]>
Cc: Vipin Sharma <[email protected]>
Cc: Jonathan Corbet <[email protected]>

Andrei Vagin (3):
  cgroup, binfmt_elf: Add hwcap masks to the misc controller
  selftests/cgroup: Add a test for the misc.mask cgroup interface
  Documentation: cgroup-v2: Document misc.mask interface

 Documentation/admin-guide/cgroup-v2.rst    |  25 ++++
 Documentation/arch/arm64/elf_hwcaps.rst    |  21 ++++
 fs/binfmt_elf.c                            |  24 +++-
 include/linux/misc_cgroup.h                |  25 ++++
 kernel/cgroup/misc.c                       | 126 +++++++++++++++++++++
 tools/testing/selftests/cgroup/.gitignore  |   1 +
 tools/testing/selftests/cgroup/Makefile    |   2 +
 tools/testing/selftests/cgroup/config      |   1 +
 tools/testing/selftests/cgroup/test_misc.c | 114 +++++++++++++++++++
 9 files changed, 335 insertions(+), 4 deletions(-)
 create mode 100644 tools/testing/selftests/cgroup/test_misc.c