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Subject[PATCH 3.11 018/208] x86/apic: Disable I/O APIC before shutdown of the local APIC
Date
3.11.10.3 -stable review patch.  If anyone has any objections, please let me know.

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

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

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@intel.com>
Link: http://lkml.kernel.org/r/1382578212-4677-1-git-send-email-fenghua.yu@intel.com
[ I suppose the 'issue' is a hang during shutdown. It's a fine change nevertheless. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
[ luis: backported to 3.11: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.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 74467fe..0b9d44d 100644
--- a/arch/x86/kernel/crash.c
+++ b/arch/x86/kernel/crash.c
@@ -127,10 +127,10 @@ void native_machine_crash_shutdown(struct pt_regs *regs)
cpu_emergency_vmxoff();
cpu_emergency_svm_disable();

- lapic_shutdown();
#if defined(CONFIG_X86_IO_APIC)
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 5f4ad27..ca1787b 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -542,6 +542,10 @@ 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
@@ -554,10 +558,6 @@ 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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