x86: fix NMI watchdog & 'stopped time' problem

More than 3 years ago Niclas Gustafsson reported a 'stopped time'
problem:

> Watching the /proc/interrupts with 10s apart after the "stop".
>
> [root@s151 root]# more /proc/interrupts
>            CPU0
>   0:   66413955  local-APIC-edge  timer
[...]
> LOC:   67355837
> ERR:          0
> MIS:          0
> [root@s151 root]# more /proc/interrupts
>            CPU0
>   0:   66413955  local-APIC-edge  timer
[...]
> LOC:   67379568
> ERR:          0
> MIS:          0

This may be because buggy SMM firmware messes with the 8259A (configured
for a transparent mode -- yes that rare "local-APIC-edge" mode is tricky
;-) ) insanely.

this should resolve:

  http://bugzilla.kernel.org/show_bug.cgi?id=2544
  http://bugzilla.kernel.org/show_bug.cgi?id=6296

Patch-dusted-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

2 files changed, 17 insertions, 4 deletions

diff --git a/arch/x86/kernel/io_apic_32.c b/arch/x86/kernel/io_apic_32.c
index f35c6eb33da9..fc4bbc1d1331 100644
--- a/arch/x86/kernel/io_apic_32.c
+++ b/arch/x86/kernel/io_apic_32.c
@@ -2166,6 +2166,10 @@ static inline void __init check_timer(void)
 {
 	int apic1, pin1, apic2, pin2;
 	int vector;
+	unsigned int ver;
+
+	ver = apic_read(APIC_LVR);
+	ver = GET_APIC_VERSION(ver);
 
 	/*
 	 * get/set the timer IRQ vector:
@@ -2179,11 +2183,15 @@ static inline void __init check_timer(void)
 	 * mode for the 8259A whenever interrupts are routed
 	 * through I/O APICs.  Also IRQ0 has to be enabled in
 	 * the 8259A which implies the virtual wire has to be
-	 * disabled in the local APIC.
+	 * disabled in the local APIC.  Finally timer interrupts
+	 * need to be acknowledged manually in the 8259A for
+	 * timer_interrupt() and for the i82489DX when using
+	 * the NMI watchdog.
 	 */
 	apic_write_around(APIC_LVT0, APIC_LVT_MASKED | APIC_DM_EXTINT);
 	init_8259A(1);
-	timer_ack = 1;
+	timer_ack = !cpu_has_tsc;
+	timer_ack |= (nmi_watchdog == NMI_IO_APIC && !APIC_INTEGRATED(ver));
 	if (timer_over_8254 > 0)
 		enable_8259A_irq(0);
 
diff --git a/arch/x86/kernel/nmi_32.c b/arch/x86/kernel/nmi_32.c
index 600fd404e440..f5cc47c60b13 100644
--- a/arch/x86/kernel/nmi_32.c
+++ b/arch/x86/kernel/nmi_32.c
@@ -25,6 +25,7 @@
 
 #include <asm/smp.h>
 #include <asm/nmi.h>
+#include <asm/timer.h>
 
 #include "mach_traps.h"
 
@@ -83,7 +84,7 @@ static int __init check_nmi_watchdog(void)
 
 	prev_nmi_count = kmalloc(NR_CPUS * sizeof(int), GFP_KERNEL);
 	if (!prev_nmi_count)
-		return -1;
+		goto error;
 
 	printk(KERN_INFO "Testing NMI watchdog ... ");
 
@@ -117,7 +118,7 @@ static int __init check_nmi_watchdog(void)
 	if (!atomic_read(&nmi_active)) {
 		kfree(prev_nmi_count);
 		atomic_set(&nmi_active, -1);
-		return -1;
+		goto error;
 	}
 	printk("OK.\n");
 
@@ -128,6 +129,10 @@ static int __init check_nmi_watchdog(void)
 
 	kfree(prev_nmi_count);
 	return 0;
+error:
+	timer_ack = !cpu_has_tsc;
+
+	return -1;
 }
 /* This needs to happen later in boot so counters are working */
 late_initcall(check_nmi_watchdog);