x86/apic: Disable I/O APIC before shutdown of the local APIC

x86/apic: Disable I/O APIC before shutdown of the local APIC

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 <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Cc: <[email protected]>
[ I suppose the 'issue' is a hang during shutdown. It's a fine change nevertheless. ]
Signed-off-by: Ingo Molnar <[email protected]>