iommu, x86: Implement irq_set_vcpu_affinity for intel_ir_chip

Interrupt chip callback to set the VCPU affinity for posted interrupts.

[ tglx: Use the helper function to copy from the remap irte instead of
        open coding it. Massage the comment as well ]

Signed-off-by: Feng Wu <feng.wu@intel.com>
Reviewed-by: Jiang Liu <jiang.liu@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: David Woodhouse <David.Woodhouse@intel.com>
Cc: iommu@lists.linux-foundation.org
Cc: joro@8bytes.org
Cc: dwmw2@infradead.org
Link: http://lkml.kernel.org/r/1433827237-3382-5-git-send-email-feng.wu@intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/arch/x86/include/asm/irq_remapping.h b/arch/x86/include/asm/irq_remapping.h
index 8b432dd..e479fbd 100644
--- a/arch/x86/include/asm/irq_remapping.h
+++ b/arch/x86/include/asm/irq_remapping.h
@@ -57,6 +57,11 @@
 	return x86_vector_domain;
 }
 
+struct vcpu_data {
+	u64 pi_desc_addr;	/* Physical address of PI Descriptor */
+	u32 vector;		/* Guest vector of the interrupt */
+};
+
 #else  /* CONFIG_IRQ_REMAP */
 
 static inline void set_irq_remapping_broken(void) { }