KVM: Add an arch specific hooks in 'struct kvm_kernel_irqfd'

This patch adds an arch specific hooks 'arch_update' in
'struct kvm_kernel_irqfd'. On Intel side, it is used to
update the IRTE when VT-d posted-interrupts is used.

Signed-off-by: Feng Wu <feng.wu@intel.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

include/linux/kvm_host.h

@@ -1172,5 +1172,7 @@ void kvm_arch_irq_bypass_del_producer(struct irq_bypass_consumer *,
 			   struct irq_bypass_producer *);
 void kvm_arch_irq_bypass_stop(struct irq_bypass_consumer *);
 void kvm_arch_irq_bypass_start(struct irq_bypass_consumer *);
+int kvm_arch_update_irqfd_routing(struct kvm *kvm, unsigned int host_irq,
+				  uint32_t guest_irq, bool set);
 #endif /* CONFIG_HAVE_KVM_IRQ_BYPASS */
 #endif

virt/kvm/eventfd.c

@@ -266,6 +266,13 @@ void __attribute__((weak)) kvm_arch_irq_bypass_start(
 				struct irq_bypass_consumer *cons)
 {
 }
+
+int  __attribute__((weak)) kvm_arch_update_irqfd_routing(
+				struct kvm *kvm, unsigned int host_irq,
+				uint32_t guest_irq, bool set)
+{
+	return 0;
+}
 #endif
 
 static int
@@ -586,9 +593,19 @@ void kvm_irq_routing_update(struct kvm *kvm)
 
 	spin_lock_irq(&kvm->irqfds.lock);
 
-	list_for_each_entry(irqfd, &kvm->irqfds.items, list)
+	list_for_each_entry(irqfd, &kvm->irqfds.items, list) {
 		irqfd_update(kvm, irqfd);
 
+#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
+		if (irqfd->producer) {
+			int ret = kvm_arch_update_irqfd_routing(
+					irqfd->kvm, irqfd->producer->irq,
+					irqfd->gsi, 1);
+			WARN_ON(ret);
+		}
+#endif
+	}
+
 	spin_unlock_irq(&kvm->irqfds.lock);
 }