[PATCH v8 08/15] x86/split_lock: Enumerate split lock detection on Icelake mobile processor

[Fenghua Yu]

Icelake mobile processor can detect split lock operations although
the processor doesn't have MSR IA32_CORE_CAPABILITY and split lock
detection bit in the MSR. Set split lock detection feature bit
X86_FEATURE_SPLIT_LOCK_DETECT on the processor based on its
family/model/stepping.

In the future, a few other processors may also have the split lock
detection feature but don't have MSR IA32_CORE_CAPABILITY. The feature
will be enumerated on those processors once their family/model/stepping
information is released.

Signed-off-by: Fenghua Yu <fenghua.yu@xxxxxxxxx>
---
 arch/x86/kernel/cpu/intel.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 86a3a646e0ce..d7e676c2aebf 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -1038,8 +1038,18 @@ void __init cpu_set_core_cap_bits(struct cpuinfo_x86 *c)
 {
 	u64 ia32_core_cap = 0;
 
-	if (!cpu_has(c, X86_FEATURE_CORE_CAPABILITY))
+	if (!cpu_has(c, X86_FEATURE_CORE_CAPABILITY)) {
+		/*
+		 * The following processors have split lock detection feature.
+		 * But since they don't have MSR IA32_CORE_CAPABILITY, the
+		 * feature cannot be enumerated by the MSR. So enumerate the
+		 * feature by family/model/stepping.
+		 */
+		if (c->x86 == 6 && c->x86_model == INTEL_FAM6_ICELAKE_MOBILE)
+			set_split_lock_detect();
+
 		return;
+	}
 
 	/*
 	 * If MSR_IA32_CORE_CAPABILITY exists, enumerate features that are
-- 
2.19.1