[PATCH v9 07/17] x86/split_lock: Enumerate split lock detection on Icelake mobile processor

Fenghua Yu
2019-06-18T22:52:22Z

Icelake mobile processor can detect split lock operations although
the processor doesn't have MSR IA32_CORE_CAP 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_CAP. The feature
will be enumerated on those processors once their family/model/stepping
information is released.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
---
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 d63a4ba203e1..7ae6cc22657d 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -1005,8 +1005,18 @@ 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_CAP, 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)
+ split_lock_setup();
+
return;
+ }

/*
* If MSR_IA32_CORE_CAP exists, enumerate features that are
--
2.19.1