perf/x86: Detect number of instances of uncore CBox

The CBox manages the interface between the core and the LLC, so
the instances of uncore CBox is equal to number of cores.
Reported-by: Andrew Cooks <acooks@gmail.com>
Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1341381616-12229-4-git-send-email-zheng.z.yan@intel.comSigned-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/kernel/cpu/perf_event_intel_uncore.c

@@ -1605,8 +1605,9 @@ static void __init uncore_cpu_setup(void *dummy)
 
 static int __init uncore_cpu_init(void)
 {
-	int ret, cpu;
+	int ret, cpu, max_cores;
 
+	max_cores = boot_cpu_data.x86_max_cores;
 	switch (boot_cpu_data.x86_model) {
 	case 26: /* Nehalem */
 	case 30:
@@ -1615,9 +1616,13 @@ static int __init uncore_cpu_init(void)
 		msr_uncores = nhm_msr_uncores;
 		break;
 	case 42: /* Sandy Bridge */
+		if (snb_uncore_cbox.num_boxes > max_cores)
+			snb_uncore_cbox.num_boxes = max_cores;
 		msr_uncores = snb_msr_uncores;
 		break;
 	case 45: /* Sandy Birdge-EP */
+		if (snbep_uncore_cbox.num_boxes > max_cores)
+			snbep_uncore_cbox.num_boxes = max_cores;
 		msr_uncores = snbep_msr_uncores;
 		break;
 	default: