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@li... [2]. https://lore.kernel.org/all/20230424001956.21434-1-ricardo.neri-calderon@lin... [3]. https://lore.kernel.org/lkml/20230805012421.7002-1-ricardo.neri-calderon@lin... [4]. https://lore.kernel.org/lkml/20230912032350.GA17008@ranerica-svr.sc.intel.co... [5]. https://lore.kernel.org/all/20230412185759.755408-1-rrendec@redhat.com/
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(-)