[PATCH 3/3] x86, cacheinfo: Calculate L3 indexes

[Borislav Petkov]

We need to know the valid L3 indexes interval when disabling them over
/sysfs. Do that when the core is brought online and add boundary checks
to the sysfs .store attribute.

Signed-off-by: Borislav Petkov <borislav.petkov@xxxxxxx>
---
 arch/x86/kernel/cpu/intel_cacheinfo.c |   29 ++++++++++++++++++++++++++++-
 1 files changed, 28 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kernel/cpu/intel_cacheinfo.c b/arch/x86/kernel/cpu/intel_cacheinfo.c
index 53e28e4..fcb29c8 100644
--- a/arch/x86/kernel/cpu/intel_cacheinfo.c
+++ b/arch/x86/kernel/cpu/intel_cacheinfo.c
@@ -151,6 +151,7 @@ struct _cpuid4_info {
 	union _cpuid4_leaf_ecx ecx;
 	unsigned long size;
 	unsigned long can_disable;
+	unsigned int l3_indexes;
 	DECLARE_BITMAP(shared_cpu_map, NR_CPUS);
 };
 
@@ -161,6 +162,7 @@ struct _cpuid4_info_regs {
 	union _cpuid4_leaf_ecx ecx;
 	unsigned long size;
 	unsigned long can_disable;
+	unsigned int l3_indexes;
 };
 
 unsigned short			num_cache_leaves;
@@ -290,6 +292,29 @@ amd_cpuid4(int leaf, union _cpuid4_leaf_eax *eax,
 		(ebx->split.ways_of_associativity + 1) - 1;
 }
 
+static unsigned int __cpuinit amd_calc_l3_indexes(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)
 {
@@ -306,6 +331,7 @@ amd_check_l3_disable(int index, struct _cpuid4_info_regs *this_leaf)
 		return;
 
 	this_leaf->can_disable = 1;
+	this_leaf->l3_indexes  = amd_calc_l3_indexes();
 }
 
 static int
@@ -769,7 +795,8 @@ static ssize_t store_cache_disable(struct _cpuid4_info *this_leaf,
 		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_indexes))
 		return -EINVAL;
 
 	val |= BIT(30);
-- 
1.6.6

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