cacheinfo: Add function to get cacheinfo for a given CPU and cache level

Resctrl open codes a search for information about a given cache level in
a couple of places (and more are on the way).

Provide a new inline function get_cpu_cacheinfo_level() in
<linux/cacheinfo.h> to do the search and return a pointer to the
cacheinfo structure.

Add lockdep_assert_cpus_held() to enforce the comment that cpuhp lock
must be held.

Simplify the existing get_cpu_cacheinfo_id() by using this new function
to do the search.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lore.kernel.org/r/20240610003927.341707-4-tony.luck@intel.com

diff --git a/include/linux/cacheinfo.h b/include/linux/cacheinfo.h
index 2cb15fe4fe12919fb11983c3ec2c89e96a68a5a8..3dde175f4108822336669f4b84b737605cd92f0b 100644 (file)
--- a/include/linux/cacheinfo.h
+++ b/include/linux/cacheinfo.h
@@ -3,6 +3,7 @@
 #define _LINUX_CACHEINFO_H
 
 #include <linux/bitops.h>
+#include <linux/cpuhplock.h>
 #include <linux/cpumask.h>
 #include <linux/smp.h>
 
@@ -113,23 +114,37 @@ int acpi_get_cache_info(unsigned int cpu,
 const struct attribute_group *cache_get_priv_group(struct cacheinfo *this_leaf);
 
 /*
- * Get the id of the cache associated with @cpu at level @level.
+ * Get the cacheinfo structure for the cache associated with @cpu at
+ * level @level.
  * cpuhp lock must be held.
  */
-static inline int get_cpu_cacheinfo_id(int cpu, int level)
+static inline struct cacheinfo *get_cpu_cacheinfo_level(int cpu, int level)
 {
        struct cpu_cacheinfo *ci = get_cpu_cacheinfo(cpu);
        int i;
 
+       lockdep_assert_cpus_held();
+
        for (i = 0; i < ci->num_leaves; i++) {
                if (ci->info_list[i].level == level) {
                        if (ci->info_list[i].attributes & CACHE_ID)
-                               return ci->info_list[i].id;
-                       return -1;
+                               return &ci->info_list[i];
+                       return NULL;
                }
        }
 
-       return -1;
+       return NULL;
+}
+
+/*
+ * Get the id of the cache associated with @cpu at level @level.
+ * cpuhp lock must be held.
+ */
+static inline int get_cpu_cacheinfo_id(int cpu, int level)
+{
+       struct cacheinfo *ci = get_cpu_cacheinfo_level(cpu, level);
+
+       return ci ? ci->id : -1;
 }
 
 #ifdef CONFIG_ARM64