linux-kernel - [PATCH] x86/apic: Disable I/O APIC before shutdown local APIC

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Message-Id: <1382578212-4677-1-git-send-email-fenghua.yu@intel.com>
Date:	Wed, 23 Oct 2013 18:30:12 -0700
From:	"Fenghua Yu" <fenghua.yu@...el.com>
To:	"H Peter Anvin" <hpa@...or.com>, "Ingo Molnar" <mingo@...e.hu>,
	"Thomas Gleixner" <tglx@...utronix.de>,
	"linux-kernel" <linux-kernel@...r.kernel.org>
Cc:	"Fenghua Yu" <fenghua.yu@...el.com>
Subject: [PATCH] x86/apic: Disable I/O APIC before shutdown local APIC

From: Fenghua Yu <fenghua.yu@...el.com>

In reboot and crash path, when shutdown local APIC, I/O APIC is still active.
This may cause issues because external interrupts can still come in and
disturb local APIC during shutdown process. To quiet external interrupts,
disable I/O APIC before shutdown local APIC.

Signed-off-by: Fenghua Yu <fenghua.yu@...el.com>
---
 arch/x86/kernel/crash.c  |    2 +-
 arch/x86/kernel/reboot.c |    8 ++++----
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
index e0e0841..18677a9 100644
--- a/arch/x86/kernel/crash.c
+++ b/arch/x86/kernel/crash.c
@@ -127,12 +127,12 @@ void native_machine_crash_shutdown(struct pt_regs *regs)
 	cpu_emergency_vmxoff();
 	cpu_emergency_svm_disable();
 
-	lapic_shutdown();
 #ifdef CONFIG_X86_IO_APIC
 	/* Prevent crash_kexec() from deadlocking on ioapic_lock. */
 	ioapic_zap_locks();
 	disable_IO_APIC();
 #endif
+	lapic_shutdown();
 #ifdef CONFIG_HPET_TIMER
 	hpet_disable();
 #endif
diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index 7e920bf..618ce26 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -550,6 +550,10 @@ static void native_machine_emergency_restart(void)
 void native_machine_shutdown(void)
 {
 	/* Stop the cpus and apics */
+#ifdef CONFIG_X86_IO_APIC
+	disable_IO_APIC();
+#endif
+
 #ifdef CONFIG_SMP
 	/*
 	 * Stop all of the others. Also disable the local irq to
@@ -562,10 +566,6 @@ void native_machine_shutdown(void)
 
 	lapic_shutdown();
 
-#ifdef CONFIG_X86_IO_APIC
-	disable_IO_APIC();
-#endif
-
 #ifdef CONFIG_HPET_TIMER
 	hpet_disable();
 #endif
-- 
1.6.0.3

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