cacheinfo: Move resctrl's get_cache_id() to the cacheinfo header file

resctrl/core.c defines get_cache_id() for use in its cpu-hotplug
callbacks. This gets the id attribute of the cache at the corresponding
level of a CPU.

Later rework means this private function needs to be shared. Move
it to the header file.

The name conflicts with a different definition in intel_cacheinfo.c,
name it get_cpu_cacheinfo_id() to show its relation with
get_cpu_cacheinfo().

Now this is visible on other architectures, check the id attribute
has actually been set.

Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Babu Moger <babu.moger@amd.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lkml.kernel.org/r/20200708163929.2783-11-james.morse@arm.com

Author: James Morse

arch/x86/kernel/cpu/resctrl/core.c

@@ -350,19 +350,6 @@ static void rdt_get_cdp_l2_config(void)
 	rdt_get_cdp_config(RDT_RESOURCE_L2, RDT_RESOURCE_L2CODE);
 }
 
-static int get_cache_id(int cpu, int level)
-{
-	struct cpu_cacheinfo *ci = get_cpu_cacheinfo(cpu);
-	int i;
-
-	for (i = 0; i < ci->num_leaves; i++) {
-		if (ci->info_list[i].level == level)
-			return ci->info_list[i].id;
-	}
-
-	return -1;
-}
-
 static void
 mba_wrmsr_amd(struct rdt_domain *d, struct msr_param *m, struct rdt_resource *r)
 {
@@ -560,7 +547,7 @@ static int domain_setup_mon_state(struct rdt_resource *r, struct rdt_domain *d)
  */
 static void domain_add_cpu(int cpu, struct rdt_resource *r)
 {
-	int id = get_cache_id(cpu, r->cache_level);
+	int id = get_cpu_cacheinfo_id(cpu, r->cache_level);
 	struct list_head *add_pos = NULL;
 	struct rdt_domain *d;
 
@@ -606,7 +593,7 @@ static void domain_add_cpu(int cpu, struct rdt_resource *r)
 
 static void domain_remove_cpu(int cpu, struct rdt_resource *r)
 {
-	int id = get_cache_id(cpu, r->cache_level);
+	int id = get_cpu_cacheinfo_id(cpu, r->cache_level);
 	struct rdt_domain *d;
 
 	d = rdt_find_domain(r, id, NULL);

include/linux/cacheinfo.h

@@ -3,6 +3,7 @@
 #define _LINUX_CACHEINFO_H
 
 #include <linux/bitops.h>
+#include <linux/cpu.h>
 #include <linux/cpumask.h>
 #include <linux/smp.h>
 
@@ -119,4 +120,24 @@ int acpi_find_last_cache_level(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.
+ * cpuhp lock must be held.
+ */
+static inline int get_cpu_cacheinfo_id(int cpu, int level)
+{
+	struct cpu_cacheinfo *ci = get_cpu_cacheinfo(cpu);
+	int i;
+
+	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 -1;
+}
+
 #endif /* _LINUX_CACHEINFO_H */