diff --git a/arch/x86/kernel/cpu/intel_cacheinfo.c b/arch/x86/kernel/cpu/intel_cacheinfo.c
index 3976ce9..589b705 100644
--- a/arch/x86/kernel/cpu/intel_cacheinfo.c
+++ b/arch/x86/kernel/cpu/intel_cacheinfo.c
@@ -151,7 +151,8 @@
 	union _cpuid4_leaf_ebx ebx;
 	union _cpuid4_leaf_ecx ecx;
 	unsigned long size;
-	unsigned long can_disable;
+	bool can_disable;
+	unsigned int l3_indices;
 	DECLARE_BITMAP(shared_cpu_map, NR_CPUS);
 };
 
@@ -161,7 +162,8 @@
 	union _cpuid4_leaf_ebx ebx;
 	union _cpuid4_leaf_ecx ecx;
 	unsigned long size;
-	unsigned long can_disable;
+	bool can_disable;
+	unsigned int l3_indices;
 };
 
 unsigned short			num_cache_leaves;
@@ -291,6 +293,29 @@
 		(ebx->split.ways_of_associativity + 1) - 1;
 }
 
+static unsigned int __cpuinit amd_calc_l3_indices(void)
+{
+	/*
+	 * We're called over smp_call_function_single() and therefore
+	 * are on the correct cpu.
+	 */
+	int cpu = smp_processor_id();
+	int node = cpu_to_node(cpu);
+	struct pci_dev *dev = node_to_k8_nb_misc(node);
+	unsigned int sc0, sc1, sc2, sc3;
+	u32 val;
+
+	pci_read_config_dword(dev, 0x1C4, &val);
+
+	/* calculate subcache sizes */
+	sc0 = !(val & BIT(0));
+	sc1 = !(val & BIT(4));
+	sc2 = !(val & BIT(8))  + !(val & BIT(9));
+	sc3 = !(val & BIT(12)) + !(val & BIT(13));
+
+	return (max(max(max(sc0, sc1), sc2), sc3) << 10) - 1;
+}
+
 static void __cpuinit
 amd_check_l3_disable(int index, struct _cpuid4_info_regs *this_leaf)
 {
@@ -306,7 +331,8 @@
 	     (boot_cpu_data.x86_mask  < 0x1)))
 		return;
 
-	this_leaf->can_disable = 1;
+	this_leaf->can_disable = true;
+	this_leaf->l3_indices  = amd_calc_l3_indices();
 }
 
 static int
@@ -765,7 +791,8 @@
 		return -EINVAL;
 
 	/* do not allow writes outside of allowed bits */
-	if (val & ~(SUBCACHE_MASK | SUBCACHE_INDEX))
+	if ((val & ~(SUBCACHE_MASK | SUBCACHE_INDEX)) ||
+	    ((val & SUBCACHE_INDEX) > this_leaf->l3_indices))
 		return -EINVAL;
 
 	val |= BIT(30);