[PATCH v4 07/17] x86/split_lock: Enumerate #AC for split lock by MSR IA32_CORE_CAPABILITY

Fenghua Yu
2019-03-02T02:45:01Z

Bits in MSR IA32_CORE_CAPABILITY enumerate features that are not
enumerated through CPUID. Currently bit 5 is defined to enumerate
feature of #AC for split lock accesses. All other bits are reserved now.

When the bit 5 is 1, the feature is supported and feature bit
X86_FEATURE_SPLIT_LOCK_DETECT is set. Otherwise, the feature is not
available.

The MSR IA32_CORE_CAPABILITY itself is enumerated by
CPUID.(EAX=0x7,ECX=0):EDX[30].

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
---
arch/x86/include/asm/cpu.h | 5 +++++
arch/x86/include/asm/cpufeatures.h | 1 +
arch/x86/kernel/cpu/common.c | 1 +
arch/x86/kernel/cpu/cpuid-deps.c | 1 +
arch/x86/kernel/cpu/intel.c | 21 +++++++++++++++++++++
5 files changed, 29 insertions(+)

diff --git a/arch/x86/include/asm/cpu.h b/arch/x86/include/asm/cpu.h
index adc6cc86b062..e241abce1a2a 100644
--- a/arch/x86/include/asm/cpu.h
+++ b/arch/x86/include/asm/cpu.h
@@ -40,4 +40,9 @@ 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);
+#ifdef CONFIG_CPU_SUP_INTEL
+void init_core_capability(struct cpuinfo_x86 *c);
+#else
+static inline void init_core_capability(struct cpuinfo_x86 *c) {}
+#endif
#endif /* _ASM_X86_CPU_H */
diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 350eeccd0ce9..54c73e74213d 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -221,6 +221,7 @@
#define X86_FEATURE_ZEN ( 7*32+28) /* "" CPU is AMD family 0x17 (Zen) */
#define X86_FEATURE_L1TF_PTEINV ( 7*32+29) /* "" L1TF workaround PTE inversion */
#define X86_FEATURE_IBRS_ENHANCED ( 7*32+30) /* Enhanced IBRS */
+#define X86_FEATURE_SPLIT_LOCK_DETECT ( 7*32+31) /* #AC for split lock */

/* Virtualization flags: Linux defined, word 8 */
#define X86_FEATURE_TPR_SHADOW ( 8*32+ 0) /* Intel TPR Shadow */
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 51ab37ba5f64..79e7cc0c4c85 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -897,6 +897,7 @@ void get_cpu_cap(struct cpuinfo_x86 *c)

init_scattered_cpuid_features(c);
init_speculation_control(c);
+ init_core_capability(c);

/*
* Clear/Set all flags overridden by options, after probe.
diff --git a/arch/x86/kernel/cpu/cpuid-deps.c b/arch/x86/kernel/cpu/cpuid-deps.c
index 2c0bd38a44ab..5ba11ce99f92 100644
--- a/arch/x86/kernel/cpu/cpuid-deps.c
+++ b/arch/x86/kernel/cpu/cpuid-deps.c
@@ -59,6 +59,7 @@ static const struct cpuid_dep cpuid_deps[] = {
{ X86_FEATURE_AVX512_4VNNIW, X86_FEATURE_AVX512F },
{ X86_FEATURE_AVX512_4FMAPS, X86_FEATURE_AVX512F },
{ X86_FEATURE_AVX512_VPOPCNTDQ, X86_FEATURE_AVX512F },
+ { X86_FEATURE_SPLIT_LOCK_DETECT, X86_FEATURE_CORE_CAPABILITY},
{}
};

diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index fc3c07fe7df5..0c44c49f6005 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -1029,3 +1029,24 @@ static const struct cpu_dev intel_cpu_dev = {

cpu_dev_register(intel_cpu_dev);

+/**
+ * init_core_capability - enumerate features supported in IA32_CORE_CAPABILITY
+ * @c: pointer to cpuinfo_x86
+ *
+ * Return: void
+ */
+void init_core_capability(struct cpuinfo_x86 *c)
+{
+ /*
+ * If MSR_IA32_CORE_CAPABILITY exists, enumerate features that are
+ * reported in the MSR.
+ */
+ if (c == &boot_cpu_data && cpu_has(c, X86_FEATURE_CORE_CAPABILITY)) {
+ u64 val;
+
+ rdmsrl(MSR_IA32_CORE_CAPABILITY, val);
+
+ if (val & CORE_CAP_SPLIT_LOCK_DETECT)
+ setup_force_cpu_cap(X86_FEATURE_SPLIT_LOCK_DETECT);
+ }
+}
--
2.7.4