[PATCH v4 0/4] x86/cacheinfo: Set the number of leaves per CPU

[Ricardo Neri]

Hi,

The interface /sys/devices/system/cpu/cpuX/cache is broken (not populated)
if CPUs have different numbers of subleaves in CPUID 4. This is the case
of Intel Meteor Lake.

This is v4 of a patchset to fix the cache sysfs interface by setting the
number of cache leaves independently for each CPU.

v1, v2, and v3 can be found here[1], here[2], and here[3].

All the tests described in [4] passed.

Changes since v3:
  * Fixed another NULL-pointer dereference when checking the validity of
    the last-level cache info.
  * Added the Reviewed-by tags from Radu and Sudeep. Thanks!
  * Rebased on v6.7-rc5.

Changes since v2:
  * This version uncovered a NULL-pointer dereference in recent changes to
    cacheinfo[5]. This dereference is observed when the system does not
    configure cacheinfo early during boot nor makes corrections later
    during CPU hotplug; as is the case in x86. Patch 1 fixes this issue.

Changes since v1:
  * Dave Hansen suggested to use the existing per-CPU ci_cpu_cacheinfo
    variable. Now the global variable num_cache_leaves became useless.
  * While here, I noticed that init_cache_level() also became useless:
    x86 does not need ci_cpu_cacheinfo::num_levels.

Thanks and BR,
Ricardo

[1]. https://lore.kernel.org/lkml/20230314231658.30169-1-ricardo.neri-calderon@xxxxxxxxxxxxxxx/
[2]. https://lore.kernel.org/all/20230424001956.21434-1-ricardo.neri-calderon@xxxxxxxxxxxxxxx/
[3]. https://lore.kernel.org/lkml/20230805012421.7002-1-ricardo.neri-calderon@xxxxxxxxxxxxxxx/
[4]. https://lore.kernel.org/lkml/20230912032350.GA17008@xxxxxxxxxxxxxxxxxxxxxxxxx/
[5]. https://lore.kernel.org/all/20230412185759.755408-1-rrendec@xxxxxxxxxx/

Ricardo Neri (4):
  cacheinfo: Check for null last-level cache info
  cacheinfo: Allocate memory for memory if not done from the primary CPU
  x86/cacheinfo: Delete global num_cache_leaves
  x86/cacheinfo: Clean out init_cache_level()

 arch/x86/kernel/cpu/cacheinfo.c | 49 +++++++++++++++++----------------
 drivers/base/cacheinfo.c        |  9 +++++-
 2 files changed, 34 insertions(+), 24 deletions(-)

-- 
2.25.1