netdev - [PATCH v7 10/21] x86/split_lock: Define per CPU variable to cache MSR TEST

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Date:   Wed, 17 Apr 2019 14:34:00 -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>,
        Xiaoyao Li <xiaoyao.li@...ux.intel.com>
Subject: [PATCH v7 10/21] x86/split_lock: Define per CPU variable to cache MSR TEST_CTL

MSR TEST_CTL (0x33) value is cached in per CPU variable msr_test_ctl_cache.
The cached value will be used in virutalization to avoid costly MSR read.

Signed-off-by: Fenghua Yu <fenghua.yu@...el.com>
Signed-off-by: Xiaoyao Li <xiaoyao.li@...ux.intel.com>
---
 arch/x86/include/asm/cpu.h  | 1 +
 arch/x86/kernel/cpu/intel.c | 3 +++
 2 files changed, 4 insertions(+)

diff --git a/arch/x86/include/asm/cpu.h b/arch/x86/include/asm/cpu.h
index 4e03f53fc079..cd7493f20234 100644
--- a/arch/x86/include/asm/cpu.h
+++ b/arch/x86/include/asm/cpu.h
@@ -40,6 +40,7 @@ int mwait_usable(const struct cpuinfo_x86 *);
 unsigned int x86_family(unsigned int sig);
 unsigned int x86_model(unsigned int sig);
 unsigned int x86_stepping(unsigned int sig);
+DECLARE_PER_CPU(u64, msr_test_ctl_cache);
 #ifdef CONFIG_CPU_SUP_INTEL
 void __init cpu_set_core_cap_bits(struct cpuinfo_x86 *c);
 #else
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 62f61a961eb6..997d683d3c27 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -31,6 +31,9 @@
 #include <asm/apic.h>
 #endif
 
+DEFINE_PER_CPU(u64, msr_test_ctl_cache);
+EXPORT_PER_CPU_SYMBOL_GPL(msr_test_ctl_cache);
+
 /*
  * Just in case our CPU detection goes bad, or you have a weird system,
  * allow a way to override the automatic disabling of MPX.
-- 
2.19.1