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>

6 files changed, 30 insertions, 18 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index cdd2a6e8a3b7..5e55e4623ab5 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1579,20 +1579,12 @@ and is between 256 and 4096 characters. It is defined in the file
 
         nmi_watchdog=   [KNL,BUGS=X86] Debugging features for SMP kernels
                         Format: [panic,][num]
-                        Valid num: 0,1,2
+                        Valid num: 0
                         0 - turn nmi_watchdog off
-                        1 - use the IO-APIC timer for the NMI watchdog
-                        2 - use the local APIC for the NMI watchdog using
-                        a performance counter. Note: This will use one
-                        performance counter and the local APIC's performance
-                        vector.
                         When panic is specified, panic when an NMI watchdog
                         timeout occurs.
                         This is useful when you use a panic=... timeout and
                         need the box quickly up again.
-                        Instead of 1 and 2 it is possible to use the following
-                        symbolic names: lapic and ioapic
-                        Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
 
         netpoll.carrier_timeout=
                         [NET] Specifies amount of time (in seconds) that
diff --git a/arch/x86/kernel/apic/hw_nmi.c b/arch/x86/kernel/apic/hw_nmi.c
index 2e94eb493591..c558e1101edf 100644
--- a/arch/x86/kernel/apic/hw_nmi.c
+++ b/arch/x86/kernel/apic/hw_nmi.c
@@ -99,6 +99,3 @@ static int __init register_trigger_all_cpu_backtrace(void)
 }
 early_initcall(register_trigger_all_cpu_backtrace);
 #endif
-
-/* STUB calls to mimic old nmi_watchdog behaviour */
-int unknown_nmi_panic;
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;
         }
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index cbd97da7a613..46404414d8a7 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -745,6 +745,22 @@ static struct ctl_table kern_table[] = {
                 .extra1         = &zero,
                 .extra2         = &one,
         },
+        {
+                .procname       = "nmi_watchdog",
+                .data           = &watchdog_enabled,
+                .maxlen         = sizeof (int),
+                .mode           = 0644,
+                .proc_handler   = proc_dowatchdog_enabled,
+        },
+#endif
+#if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_X86)
+        {
+                .procname       = "unknown_nmi_panic",
+                .data           = &unknown_nmi_panic,
+                .maxlen         = sizeof (int),
+                .mode           = 0644,
+                .proc_handler   = proc_dointvec,
+        },
 #endif
 #if defined(CONFIG_X86)
         {
diff --git a/kernel/sysctl_binary.c b/kernel/sysctl_binary.c
index 1357c5786064..4b2545a136ff 100644
--- a/kernel/sysctl_binary.c
+++ b/kernel/sysctl_binary.c
@@ -136,7 +136,6 @@ static const struct bin_table bin_kern_table[] = {
         { CTL_INT,      KERN_IA64_UNALIGNED,            "ignore-unaligned-usertrap" },
         { CTL_INT,      KERN_COMPAT_LOG,                "compat-log" },
         { CTL_INT,      KERN_MAX_LOCK_DEPTH,            "max_lock_depth" },
-        { CTL_INT,      KERN_NMI_WATCHDOG,              "nmi_watchdog" },
         { CTL_INT,      KERN_PANIC_ON_NMI,              "panic_on_unrecovered_nmi" },
         {}
 };
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index cad4e42060a9..eb17e143b5da 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -57,6 +57,8 @@ static int __init hardlockup_panic_setup(char *str)
 {
         if (!strncmp(str, "panic", 5))
                 hardlockup_panic = 1;
+        else if (!strncmp(str, "0", 1))
+                no_watchdog = 1;
         return 1;
 }
 __setup("nmi_watchdog=", hardlockup_panic_setup);