Export x86 cache topology

This patch adds get_shared_cpu_map(), which allows the caller to infer
which CPUs share a cache at a given level.

2 files changed, 21 insertions, 0 deletions

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 22224b3b43bb..254dd2b81632 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -173,6 +173,10 @@ void print_cpu_msr(struct cpuinfo_x86 *);
 extern void init_scattered_cpuid_features(struct cpuinfo_x86 *c);
 extern unsigned int init_intel_cacheinfo(struct cpuinfo_x86 *c);
 extern void init_amd_cacheinfo(struct cpuinfo_x86 *c);
+#ifdef CONFIG_SYSFS
+extern int get_shared_cpu_map(cpumask_var_t mask,
+                               unsigned int cpu, int index);
+#endif
 
 extern void detect_extended_topology(struct cpuinfo_x86 *c);
 extern void detect_ht(struct cpuinfo_x86 *c);
diff --git a/arch/x86/kernel/cpu/intel_cacheinfo.c b/arch/x86/kernel/cpu/intel_cacheinfo.c
index 7c6f7d548c0f..033939ba4782 100644
--- a/arch/x86/kernel/cpu/intel_cacheinfo.c
+++ b/arch/x86/kernel/cpu/intel_cacheinfo.c
@@ -744,6 +744,23 @@ unsigned int __cpuinit init_intel_cacheinfo(struct cpuinfo_x86 *c)
 static DEFINE_PER_CPU(struct _cpuid4_info *, ici_cpuid4_info);
 #define CPUID4_INFO_IDX(x, y)   (&((per_cpu(ici_cpuid4_info, x))[y]))
 
+/* returns CPUs that share the index cache with cpu */
+int get_shared_cpu_map(cpumask_var_t mask, unsigned int cpu, int index)
+{
+        int ret = 0;
+        struct _cpuid4_info *this_leaf;
+
+        if (index >= num_cache_leaves) {
+                index = num_cache_leaves - 1;
+                ret = index;
+        }
+
+        this_leaf = CPUID4_INFO_IDX(cpu,index);
+        cpumask_copy(mask, to_cpumask(this_leaf->shared_cpu_map));
+
+        return ret;
+}
+
 #ifdef CONFIG_SMP
 
 static int __cpuinit cache_shared_amd_cpu_map_setup(unsigned int cpu, int index)