[PATCH 3.8 073/152] x86/apic: Disable I/O APIC before shutdown of the local APIC

From: Kamal Mostafa
Date: Fri Dec 06 2013 - 18:40:52 EST


3.8.13.14 -stable review patch. If anyone has any objections, please let me know.

------------------

From: Fenghua Yu <fenghua.yu@xxxxxxxxx>

commit 522e66464467543c0d88d023336eec4df03ad40b upstream.

In reboot and crash path, when we shut down the local APIC, the I/O APIC is
still active. This may cause issues because external interrupts
can still come in and disturb the local APIC during shutdown process.

To quiet external interrupts, disable I/O APIC before shutdown local APIC.

Signed-off-by: Fenghua Yu <fenghua.yu@xxxxxxxxx>
Link: http://lkml.kernel.org/r/1382578212-4677-1-git-send-email-fenghua.yu@xxxxxxxxx
[ I suppose the 'issue' is a hang during shutdown. It's a fine change nevertheless. ]
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
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 90fd119..44135ec 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -629,6 +629,10 @@ 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

/* The boot cpu is always logical cpu 0 */
@@ -657,10 +661,6 @@ void native_machine_shutdown(void)

lapic_shutdown();

-#ifdef CONFIG_X86_IO_APIC
- disable_IO_APIC();
-#endif
-
#ifdef CONFIG_HPET_TIMER
hpet_disable();
#endif
--
1.8.3.2

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