From e85ceae9102f6e3c1d707e7ac88fa48d252e9cfa Mon Sep 17 00:00:00 2001
From: Jan Kiszka <jan.kiszka@siemens.com>
Date: Mon, 6 Oct 2008 13:50:59 -0500
Subject: [PATCH] kgdb, x86: Avoid invoking kgdb_nmicallback twice per NMI
Stress-testing KVM's latest NMI support with kgdbts inside an SMP guest,
I came across spurious unhandled NMIs while running the singlestep test.
Looking closer at the code path each NMI takes when KGDB is enabled, I
noticed that kgdb_nmicallback is called twice per event: One time via
DIE_NMI_IPI notification, the second time on DIE_NMI. Removing the first
invocation cures the unhandled NMIs here.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
---
arch/x86/kernel/kgdb.c | 7 +------
1 file changed, 1 insertion(+), 6 deletions(-)
diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index 8282a213968..10435a120d2 100644
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c
@@ -455,12 +455,7 @@ static int __kgdb_notify(struct die_args *args, unsigned long cmd)
return NOTIFY_DONE;
case DIE_NMI_IPI:
- if (atomic_read(&kgdb_active) != -1) {
- /* KGDB CPU roundup */
- kgdb_nmicallback(raw_smp_processor_id(), regs);
- was_in_debug_nmi[raw_smp_processor_id()] = 1;
- touch_nmi_watchdog();
- }
+ /* Just ignore, we will handle the roundup on DIE_NMI. */
return NOTIFY_DONE;
case DIE_NMIUNKNOWN:
--
2.41.3