x86, NMI: Add back unknown_nmi_panic and nmi_watchdog sysctls

Originally adapted from Huang Ying's patch which moved the
unknown_nmi_panic to the traps.c file.  Because the old nmi
watchdog was deleted before this change happened, the
unknown_nmi_panic sysctl was lost.  This re-adds it.

Also, the nmi_watchdog sysctl was re-implemented and its
documentation updated accordingly.

Patch-inspired-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Don Zickus <dzickus@redhat.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com>
Acked-by: Yinghai Lu <yinghai@kernel.org>
Cc: fweisbec@gmail.com
LKML-Reference: <1291068437-5331-3-git-send-email-dzickus@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 11 insertions, 5 deletions

diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index f02c179c2552..bb6f04167361 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -83,6 +83,8 @@ EXPORT_SYMBOL_GPL(used_vectors);
 
 static int ignore_nmis;
 
+int unknown_nmi_panic;
+
 static inline void conditional_sti(struct pt_regs *regs)
 {
         if (regs->flags & X86_EFLAGS_IF)
@@ -300,6 +302,13 @@ gp_in_kernel:
         die("general protection fault", regs, error_code);
 }
 
+static int __init setup_unknown_nmi_panic(char *str)
+{
+        unknown_nmi_panic = 1;
+        return 1;
+}
+__setup("unknown_nmi_panic", setup_unknown_nmi_panic);
+
 static notrace __kprobes void
 mem_parity_error(unsigned char reason, struct pt_regs *regs)
 {
@@ -371,7 +380,7 @@ unknown_nmi_error(unsigned char reason, struct pt_regs *regs)
                         reason, smp_processor_id());
 
         printk(KERN_EMERG "Do you have a strange power saving mode enabled?\n");
-        if (panic_on_unrecovered_nmi)
+        if (unknown_nmi_panic || panic_on_unrecovered_nmi)
                 panic("NMI: Not continuing");
 
         printk(KERN_EMERG "Dazed and confused, but trying to continue\n");
@@ -397,11 +406,8 @@ static notrace __kprobes void default_do_nmi(struct pt_regs *regs)
                 if (notify_die(DIE_NMI, "nmi", regs, reason, 2, SIGINT)
                                                         == NOTIFY_STOP)
                         return;
-
-                        unknown_nmi_error(reason, regs);
-#else
-                unknown_nmi_error(reason, regs);
 #endif
+                unknown_nmi_error(reason, regs);
 
                 return;
         }