If the interrupt destination mode of the APIC is physical then the
effective affinity is restricted to a single CPU.

Mark the interrupt accordingly in the domain allocation code, so the core
code can avoid pointless affinity setting attempts.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 arch/x86/kernel/apic/vector.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/arch/x86/kernel/apic/vector.c
+++ b/arch/x86/kernel/apic/vector.c
@@ -371,6 +371,13 @@ static int x86_vector_alloc_irqs(struct
 					       irq_data);
 		if (err)
 			goto error;
+		/*
+		 * If the apic destination mode is physical, then the
+		 * effective affinity is restricted to a single target
+		 * CPU. Mark the interrupt accordingly.
+		 */
+		if (!apic->irq_dest_mode)
+			irqd_set_single_target(irq_data);
 	}
 
 	return 0;