3 files changed, 45 insertions, 1 deletions

diff --git a/arch/i386/kernel/alternative.c b/arch/i386/kernel/alternative.c
index 206ea2ca63cc..c3750c2c4113 100644
--- a/arch/i386/kernel/alternative.c
+++ b/arch/i386/kernel/alternative.c
@@ -8,6 +8,8 @@
 #include <asm/alternative.h>
 #include <asm/sections.h>
 #include <asm/pgtable.h>
+#include <asm/mce.h>
+#include <asm/nmi.h>
 
 #ifdef CONFIG_HOTPLUG_CPU
 static int smp_alt_once;
@@ -373,6 +375,14 @@ void __init alternative_instructions(void)
 {
         unsigned long flags;
 
+        /* The patching is not fully atomic, so try to avoid local interruptions
+           that might execute the to be patched code.
+           Other CPUs are not running. */
+        stop_nmi();
+#ifdef CONFIG_MCE
+        stop_mce();
+#endif
+
         local_irq_save(flags);
         apply_alternatives(__alt_instructions, __alt_instructions_end);
 
@@ -405,6 +415,11 @@ void __init alternative_instructions(void)
 #endif
         apply_paravirt(__parainstructions, __parainstructions_end);
         local_irq_restore(flags);
+
+        restart_nmi();
+#ifdef CONFIG_MCE
+        restart_mce();
+#endif
 }
 
 /*
diff --git a/arch/i386/kernel/cpu/mcheck/mce.c b/arch/i386/kernel/cpu/mcheck/mce.c
index 56cd485b127c..34c781eddee4 100644
--- a/arch/i386/kernel/cpu/mcheck/mce.c
+++ b/arch/i386/kernel/cpu/mcheck/mce.c
@@ -60,6 +60,20 @@ void mcheck_init(struct cpuinfo_x86 *c)
         }
 }
 
+static unsigned long old_cr4 __initdata;
+
+void __init stop_mce(void)
+{
+        old_cr4 = read_cr4();
+        clear_in_cr4(X86_CR4_MCE);
+}
+
+void __init restart_mce(void)
+{
+        if (old_cr4 & X86_CR4_MCE)
+                set_in_cr4(X86_CR4_MCE);
+}
+
 static int __init mcheck_disable(char *str)
 {
         mce_disabled = 1;
diff --git a/arch/i386/kernel/traps.c b/arch/i386/kernel/traps.c
index 438949da3b63..cfffe3dd9e83 100644
--- a/arch/i386/kernel/traps.c
+++ b/arch/i386/kernel/traps.c
@@ -775,6 +775,8 @@ static __kprobes void default_do_nmi(struct pt_regs * regs)
         reassert_nmi();
 }
 
+static int ignore_nmis;
+
 fastcall __kprobes void do_nmi(struct pt_regs * regs, long error_code)
 {
         int cpu;
@@ -785,11 +787,24 @@ fastcall __kprobes void do_nmi(struct pt_regs * regs, long error_code)
 
         ++nmi_count(cpu);
 
-        default_do_nmi(regs);
+        if (!ignore_nmis)
+                default_do_nmi(regs);
 
         nmi_exit();
 }
 
+void stop_nmi(void)
+{
+        acpi_nmi_disable();
+        ignore_nmis++;
+}
+
+void restart_nmi(void)
+{
+        ignore_nmis--;
+        acpi_nmi_enable();
+}
+
 #ifdef CONFIG_KPROBES
 fastcall void __kprobes do_int3(struct pt_regs *regs, long error_code)
 {