[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>

1 files changed, 32 insertions, 1 deletions

diff --git a/arch/i386/kernel/io_apic.c b/arch/i386/kernel/io_apic.c
index 3c2b3bdfc807..fc81c8cddd22 100644
--- a/arch/i386/kernel/io_apic.c
+++ b/arch/i386/kernel/io_apic.c
@@ -1636,12 +1636,43 @@ static void __init enable_IO_APIC(void)
  */
 void disable_IO_APIC(void)
 {
+        int pin;
         /*
          * Clear the IO-APIC before rebooting:
          */
         clear_IO_APIC();
 
-        disconnect_bsp_APIC();
+        /*
+         * If the i82559 is routed through an IOAPIC
+         * Put that IOAPIC in virtual wire mode
+         * so legacy interrups can be delivered.
+         */
+        pin = find_isa_irq_pin(0, mp_ExtINT);
+        if (pin != -1) {
+                struct IO_APIC_route_entry entry;
+                unsigned long flags;
+
+                memset(&entry, 0, sizeof(entry));
+                entry.mask            = 0; /* Enabled */
+                entry.trigger         = 0; /* Edge */
+                entry.irr             = 0;
+                entry.polarity        = 0; /* High */
+                entry.delivery_status = 0;
+                entry.dest_mode       = 0; /* Physical */
+                entry.delivery_mode   = 7; /* ExtInt */
+                entry.vector          = 0;
+                entry.dest.physical.physical_dest = 0;
+
+
+                /*
+                 * Add it to the IO-APIC irq-routing table:
+                 */
+                spin_lock_irqsave(&ioapic_lock, flags);
+                io_apic_write(0, 0x11+2*pin, *(((int *)&entry)+1));
+                io_apic_write(0, 0x10+2*pin, *(((int *)&entry)+0));
+                spin_unlock_irqrestore(&ioapic_lock, flags);
+        }
+        disconnect_bsp_APIC(pin != -1);
 }
 
 /*