netdev - [PATCH v7 08/21] x86/split_lock: Enumerate split lock detection on Icelake mobile processor

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Message-Id: <1555536851-17462-9-git-send-email-fenghua.yu@intel.com>
Date:   Wed, 17 Apr 2019 14:33:58 -0700
From:   Fenghua Yu <fenghua.yu@...el.com>
To:     "Thomas Gleixner" <tglx@...utronix.de>,
        "Ingo Molnar" <mingo@...hat.com>, "Borislav Petkov" <bp@...en8.de>,
        "H Peter Anvin" <hpa@...or.com>,
        "Paolo Bonzini" <pbonzini@...hat.com>,
        "Dave Hansen" <dave.hansen@...el.com>,
        "Ashok Raj" <ashok.raj@...el.com>,
        "Peter Zijlstra" <peterz@...radead.org>,
        "Ravi V Shankar" <ravi.v.shankar@...el.com>,
        "Xiaoyao Li " <xiaoyao.li@...el.com>,
        "Christopherson Sean J" <sean.j.christopherson@...el.com>,
        "Kalle Valo" <kvalo@...eaurora.org>,
        "Michael Chan" <michael.chan@...adcom.com>
Cc:     "linux-kernel" <linux-kernel@...r.kernel.org>,
        "x86" <x86@...nel.org>, kvm@...r.kernel.org,
        netdev@...r.kernel.org, linux-wireless@...r.kernel.org,
        Fenghua Yu <fenghua.yu@...el.com>
Subject: [PATCH v7 08/21] x86/split_lock: Enumerate split lock detection on Icelake mobile processor

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@...el.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 ad3f72d106fc..62f61a961eb6 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