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Date: Mon, 29 Jun 2015 19:38:15 -0400
From: Ashok Raj <ashok.raj@...el.com>
To: linux-kernel@...r.kernel.org
Cc: Ashok Raj <ashok.raj@...el.com>, linux-edac@...r.kernel.org,
Boris Petkov <bp@...e.de>, Tony Luck <tony.luck@...el.com>
Subject: [Patch V1 2/2] x86, mce: clear Local MCE opt-in before kexec.
kexec could boot a kernel that could be legacy with no knowledge of LMCE.
hence we should make sure we clear LMCE optin before kexec reboot.
Signed-off-by: Ashok Raj <ashok.raj@...el.com>
---
arch/x86/include/asm/mce.h | 4 ++++
arch/x86/kernel/cpu/mcheck/mce.c | 30 ++++++++++++++++++++++++++++++
arch/x86/kernel/cpu/mcheck/mce_intel.c | 19 ++++++++++++++++++-
arch/x86/kernel/process.c | 2 ++
arch/x86/kernel/smp.c | 2 ++
5 files changed, 56 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/mce.h b/arch/x86/include/asm/mce.h
index b7a3a34..efa0bce 100644
--- a/arch/x86/include/asm/mce.h
+++ b/arch/x86/include/asm/mce.h
@@ -140,10 +140,12 @@ extern int mce_p5_enabled;
#ifdef CONFIG_X86_MCE
int mcheck_init(void);
void mcheck_cpu_init(struct cpuinfo_x86 *c);
+void mcheck_cpu_clear(struct cpuinfo_x86 *c);
void mcheck_vendor_init_severity(void);
#else
static inline int mcheck_init(void) { return 0; }
static inline void mcheck_cpu_init(struct cpuinfo_x86 *c) {}
+static inline void mcheck_cpu_clear(struct cpuinfo_x86 *c) {}
static inline void mcheck_vendor_init_severity(void) {}
#endif
@@ -170,12 +172,14 @@ DECLARE_PER_CPU(struct device *, mce_device);
#ifdef CONFIG_X86_MCE_INTEL
void mce_intel_feature_init(struct cpuinfo_x86 *c);
+void mce_intel_feature_clear(struct cpuinfo_x86 *c);
void cmci_clear(void);
void cmci_reenable(void);
void cmci_rediscover(void);
void cmci_recheck(void);
#else
static inline void mce_intel_feature_init(struct cpuinfo_x86 *c) { }
+static inline void mce_intel_feature_clear(struct cpuinfo_x86 *c) { }
static inline void cmci_clear(void) {}
static inline void cmci_reenable(void) {}
static inline void cmci_rediscover(void) {}
diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index 8a72a33..7836fe6 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -1669,6 +1669,17 @@ static void __mcheck_cpu_init_vendor(struct cpuinfo_x86 *c)
}
}
+static void __mcheck_cpu_clear_vendor(struct cpuinfo_x86 *c)
+{
+ switch (c->x86_vendor) {
+ case X86_VENDOR_INTEL:
+ mce_intel_feature_clear(c);
+ break;
+ default:
+ break;
+ }
+}
+
static void mce_start_timer(unsigned int cpu, struct timer_list *t)
{
unsigned long iv = check_interval * HZ;
@@ -1732,6 +1743,25 @@ void mcheck_cpu_init(struct cpuinfo_x86 *c)
}
/*
+ * Called for each booted CPU to clear some machine checks opt-ins
+ */
+void mcheck_cpu_clear(struct cpuinfo_x86 *c)
+{
+ if (mca_cfg.disabled)
+ return;
+
+ if (!mce_available(c))
+ return;
+
+ /*
+ * Possibly to clear general settings generic to x86
+ * __mcheck_cpu_clear_generic(c);
+ */
+ __mcheck_cpu_clear_vendor(c);
+
+}
+
+/*
* mce_chrdev: Character device /dev/mcelog to read and clear the MCE log.
*/
diff --git a/arch/x86/kernel/cpu/mcheck/mce_intel.c b/arch/x86/kernel/cpu/mcheck/mce_intel.c
index 844f56c..1cd0d9c 100644
--- a/arch/x86/kernel/cpu/mcheck/mce_intel.c
+++ b/arch/x86/kernel/cpu/mcheck/mce_intel.c
@@ -435,7 +435,7 @@ static void intel_init_cmci(void)
cmci_recheck();
}
-void intel_init_lmce(void)
+static void intel_init_lmce(void)
{
u64 val;
@@ -448,9 +448,26 @@ void intel_init_lmce(void)
wrmsrl(MSR_IA32_MCG_EXT_CTL, val | MCG_EXT_CTL_LMCE_EN);
}
+static void intel_clear_lmce(void)
+{
+ u64 val;
+
+ if (!lmce_supported())
+ return;
+
+ rdmsrl(MSR_IA32_MCG_EXT_CTL, val);
+ val &= ~MCG_EXT_CTL_LMCE_EN;
+ wrmsrl(MSR_IA32_MCG_EXT_CTL, val);
+}
+
void mce_intel_feature_init(struct cpuinfo_x86 *c)
{
intel_init_thermal(c);
intel_init_cmci();
intel_init_lmce();
}
+
+void mce_intel_feature_clear(struct cpuinfo_x86 *c)
+{
+ intel_clear_lmce();
+}
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 6e338e3..1149083 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -30,6 +30,7 @@
#include <asm/debugreg.h>
#include <asm/nmi.h>
#include <asm/tlbflush.h>
+#include <asm/mce.h>
/*
* per-CPU TSS segments. Threads are completely 'soft' on Linux,
@@ -363,6 +364,7 @@ void stop_this_cpu(void *dummy)
*/
set_cpu_online(smp_processor_id(), false);
disable_local_APIC();
+ mcheck_cpu_clear(this_cpu_ptr(&cpu_info));
for (;;)
halt();
diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c
index be8e1bd..892ffd2 100644
--- a/arch/x86/kernel/smp.c
+++ b/arch/x86/kernel/smp.c
@@ -30,6 +30,7 @@
#include <asm/proto.h>
#include <asm/apic.h>
#include <asm/nmi.h>
+#include <asm/mce.h>
#include <asm/trace/irq_vectors.h>
/*
* Some notes on x86 processor bugs affecting SMP operation:
@@ -244,6 +245,7 @@ static void native_stop_other_cpus(int wait)
finish:
local_irq_save(flags);
disable_local_APIC();
+ mcheck_cpu_clear(this_cpu_ptr(&cpu_info));
local_irq_restore(flags);
}
--
2.4.3
--
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