[PATCH] kexec: x86: resture apic virtual wire mode on shutdown

When coming out of apic mode attempt to set the appropriate
apic back into virtual wire mode.  This improves on previous versions
of this patch by by never setting bot the local apic and the ioapic
into veritual wire mode.

This code looks at data from the mptable to see if an ioapic has
an ExtInt input to make this decision.  A future improvement
is to figure out which apic or ioapic was in virtual wire mode
at boot time and to remember it.  That is potentially a more accurate
method, of selecting which apic to place in virutal wire mode.

Signed-off-by: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/asm-i386/apic.h

@@ -100,7 +100,7 @@ extern void (*wait_timer_tick)(void);
 extern int get_maxlvt(void);
 extern void clear_local_APIC(void);
 extern void connect_bsp_APIC (void);
-extern void disconnect_bsp_APIC (void);
+extern void disconnect_bsp_APIC (int virt_wire_setup);
 extern void disable_local_APIC (void);
 extern void lapic_shutdown (void);
 extern int verify_local_APIC (void);

include/asm-i386/apicdef.h

@@ -86,6 +86,7 @@
 #define			APIC_LVT_REMOTE_IRR		(1<<14)
 #define			APIC_INPUT_POLARITY		(1<<13)
 #define			APIC_SEND_PENDING		(1<<12)
+#define			APIC_MODE_MASK			0x700
 #define			GET_APIC_DELIVERY_MODE(x)	(((x)>>8)&0x7)
 #define			SET_APIC_DELIVERY_MODE(x,y)	(((x)&~0x700)|((y)<<8))
 #define				APIC_MODE_FIXED		0x0