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 <[e-mail]>
Signed-off-by: Ingo Molnar <[e-mail]>

arch/x86/kernel/io_apic.c

···
 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;
···
 			 * 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));
-#ifdef CONFIG_INTR_REMAP
-			else if (intr_remapping_enabled)
-				set_ir_ioapic_affinity_irq(irq, TARGET_CPUS);
-#endif
+				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
-				set_ioapic_affinity_irq(irq, TARGET_CPUS);
+				mask = TARGET_CPUS;
+
+#ifdef CONFIG_INTR_REMAP
+			if (intr_remapping_enabled)
+				set_ir_ioapic_affinity_irq(irq, mask);
+			else
+#endif
+				set_ioapic_affinity_irq(irq, mask);
 		}
 
 	}