From: Thomas Gleixner <tglx@linutronix.de>
Subject: x86: apic honour irq affinity which was set in early boot

commit 6c2e94033df5ca11149e52dd179b8dde3172e9bf
Author: Thomas Gleixner <tglx@linutronix.de>
Date:   Fri Nov 7 12:33:49 2008 +0100

    x86: apic honour irq affinity which was set in early boot
    
    setup_ioapic_dest() is called after the non boot cpus have been
    brought up. It sets the irq affinity of all already configured
    interrupts to all cpus and ignores affinity settings which were
    done by the early bootup code.
    
    If the IRQ_NO_BALANCING or IRQ_AFFINITY_SET flags are set then use the
    affinity mask from the irq descriptor and not TARGET_CPUS.
    
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 arch/x86/kernel/io_apic.c |   26 +++++++++++++++++++++-----
 1 file changed, 21 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/io_apic.c b/arch/x86/kernel/io_apic.c
index 7a3f202..988ee89 100644
--- a/arch/x86/kernel/io_apic.c
+++ b/arch/x86/kernel/io_apic.c
@@ -3761,7 +3761,9 @@ int acpi_get_override_irq(int bus_irq, int *trigger, int *polarity)
 void __init setup_ioapic_dest(void)
 {
 	int pin, ioapic, irq, irq_entry;
+	struct irq_desc *desc;
 	struct irq_cfg *cfg;
+	cpumask_t mask;
 
 	if (skip_ioapic_setup == 1)
 		return;
@@ -3778,16 +3780,30 @@ void __init setup_ioapic_dest(void)
 			 * cpu is online.
 			 */
 			cfg = irq_cfg(irq);
-			if (!cfg->vector)
+			if (!cfg->vector) {
 				setup_IO_APIC_irq(ioapic, pin, irq,
 						  irq_trigger(irq_entry),
 						  irq_polarity(irq_entry));
+				continue;
+
+			}
+
+			/*
+			 * Honour affinities which have been set in early boot
+			 */
+			desc = irq_to_desc(irq);
+			if (desc->status &
+			    (IRQ_NO_BALANCING | IRQ_AFFINITY_SET))
+				mask = desc->affinity;
+			else
+				mask = TARGET_CPUS;
+
 #ifdef CONFIG_INTR_REMAP
-			else if (intr_remapping_enabled)
-				set_ir_ioapic_affinity_irq(irq, TARGET_CPUS);
-#endif
+			if (intr_remapping_enabled)
+				set_ir_ioapic_affinity_irq(irq, mask);
 			else
-				set_ioapic_affinity_irq(irq, TARGET_CPUS);
+#endif
+				set_ioapic_affinity_irq(irq, mask);
 		}
 
 	}
