KVM: Fold kvm_arch_irqfd_route_changed() into kvm_arch_update_irqfd_routing()

Fold kvm_arch_irqfd_route_changed() into kvm_arch_update_irqfd_routing().
Calling arch code to know whether or not to call arch code is absurd.

Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20250611224604.313496-35-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Author: sean-jc

arch/arm64/kvm/arm.c

@@ -2761,20 +2761,15 @@ void kvm_arch_irq_bypass_del_producer(struct irq_bypass_consumer *cons,
 	kvm_vgic_v4_unset_forwarding(irqfd->kvm, prod->irq);
 }
 
-bool kvm_arch_irqfd_route_changed(struct kvm_kernel_irq_routing_entry *old,
-				  struct kvm_kernel_irq_routing_entry *new)
-{
-	if (old->type != KVM_IRQ_ROUTING_MSI ||
-	    new->type != KVM_IRQ_ROUTING_MSI)
-		return true;
-
-	return memcmp(&old->msi, &new->msi, sizeof(new->msi));
-}
-
 void kvm_arch_update_irqfd_routing(struct kvm_kernel_irqfd *irqfd,
 				   struct kvm_kernel_irq_routing_entry *old,
 				   struct kvm_kernel_irq_routing_entry *new)
 {
+	if (old->type == KVM_IRQ_ROUTING_MSI &&
+	    new->type == KVM_IRQ_ROUTING_MSI &&
+	    !memcmp(&old->msi, &new->msi, sizeof(new->msi)))
+		return;
+
 	/*
 	 * Remapping the vLPI requires taking the its_lock mutex to resolve
 	 * the new translation. We're in spinlock land at this point, so no

arch/x86/kvm/irq.c

@@ -610,17 +610,12 @@ void kvm_arch_update_irqfd_routing(struct kvm_kernel_irqfd *irqfd,
 				   struct kvm_kernel_irq_routing_entry *old,
 				   struct kvm_kernel_irq_routing_entry *new)
 {
-	kvm_pi_update_irte(irqfd, new);
-}
-
-bool kvm_arch_irqfd_route_changed(struct kvm_kernel_irq_routing_entry *old,
-				  struct kvm_kernel_irq_routing_entry *new)
-{
-	if (old->type != KVM_IRQ_ROUTING_MSI ||
-	    new->type != KVM_IRQ_ROUTING_MSI)
-		return true;
+	if (old->type == KVM_IRQ_ROUTING_MSI &&
+	    new->type == KVM_IRQ_ROUTING_MSI &&
+	    !memcmp(&old->msi, &new->msi, sizeof(new->msi)))
+		return;
 
-	return !!memcmp(&old->msi, &new->msi, sizeof(new->msi));
+	kvm_pi_update_irte(irqfd, new);
 }
 
 #ifdef CONFIG_KVM_IOAPIC

include/linux/kvm_host.h

@@ -2413,8 +2413,6 @@ void kvm_arch_irq_bypass_start(struct irq_bypass_consumer *);
 void kvm_arch_update_irqfd_routing(struct kvm_kernel_irqfd *irqfd,
 				   struct kvm_kernel_irq_routing_entry *old,
 				   struct kvm_kernel_irq_routing_entry *new);
-bool kvm_arch_irqfd_route_changed(struct kvm_kernel_irq_routing_entry *,
-				  struct kvm_kernel_irq_routing_entry *);
 #endif /* CONFIG_HAVE_KVM_IRQ_BYPASS */
 
 #ifdef CONFIG_HAVE_KVM_INVALID_WAKEUPS

virt/kvm/eventfd.c

@@ -291,13 +291,6 @@ void __weak kvm_arch_update_irqfd_routing(struct kvm_kernel_irqfd *irqfd,
 {
 
 }
-
-bool __attribute__((weak)) kvm_arch_irqfd_route_changed(
-				struct kvm_kernel_irq_routing_entry *old,
-				struct kvm_kernel_irq_routing_entry *new)
-{
-	return true;
-}
 #endif
 
 static int
@@ -616,8 +609,7 @@ void kvm_irq_routing_update(struct kvm *kvm)
 		irqfd_update(kvm, irqfd);
 
 #if IS_ENABLED(CONFIG_HAVE_KVM_IRQ_BYPASS)
-		if (irqfd->producer &&
-		    kvm_arch_irqfd_route_changed(&old, &irqfd->irq_entry))
+		if (irqfd->producer)
 			kvm_arch_update_irqfd_routing(irqfd, &old, &irqfd->irq_entry);
 #endif
 	}