KVM: x86: Move IRQ routing/delivery APIs from x86.c => irq.c

Move a bunch of IRQ routing and delivery APIs from x86.c to irq.c.  x86.c
has grown quite fat, and irq.c is the perfect landing spot.

Opportunistically rewrite kvm_arch_irq_bypass_del_producer()'s comment, as
the existing comment has several typos and is rather confusing.

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Link: https://lore.kernel.org/r/20250611224604.313496-28-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Author: sean-jc

arch/x86/kvm/irq.c

@@ -11,6 +11,7 @@
 
 #include <linux/export.h>
 #include <linux/kvm_host.h>
+#include <linux/kvm_irqfd.h>
 
 #include "hyperv.h"
 #include "ioapic.h"
@@ -332,6 +333,18 @@ int kvm_arch_set_irq_inatomic(struct kvm_kernel_irq_routing_entry *e,
 	return -EWOULDBLOCK;
 }
 
+int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_event,
+			bool line_status)
+{
+	if (!irqchip_in_kernel(kvm))
+		return -ENXIO;
+
+	irq_event->status = kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID,
+					irq_event->irq, irq_event->level,
+					line_status);
+	return 0;
+}
+
 bool kvm_arch_can_set_irq_routing(struct kvm *kvm)
 {
 	return irqchip_in_kernel(kvm);
@@ -495,6 +508,81 @@ void kvm_arch_irq_routing_update(struct kvm *kvm)
 		kvm_make_scan_ioapic_request(kvm);
 }
 
+int kvm_arch_irq_bypass_add_producer(struct irq_bypass_consumer *cons,
+				      struct irq_bypass_producer *prod)
+{
+	struct kvm_kernel_irqfd *irqfd =
+		container_of(cons, struct kvm_kernel_irqfd, consumer);
+	struct kvm *kvm = irqfd->kvm;
+	int ret = 0;
+
+	kvm_arch_start_assignment(irqfd->kvm);
+
+	spin_lock_irq(&kvm->irqfds.lock);
+	irqfd->producer = prod;
+
+	if (irqfd->irq_entry.type == KVM_IRQ_ROUTING_MSI) {
+		ret = kvm_x86_call(pi_update_irte)(irqfd, irqfd->kvm, prod->irq,
+						   irqfd->gsi, &irqfd->irq_entry);
+		if (ret)
+			kvm_arch_end_assignment(irqfd->kvm);
+	}
+	spin_unlock_irq(&kvm->irqfds.lock);
+
+	return ret;
+}
+
+void kvm_arch_irq_bypass_del_producer(struct irq_bypass_consumer *cons,
+				      struct irq_bypass_producer *prod)
+{
+	struct kvm_kernel_irqfd *irqfd =
+		container_of(cons, struct kvm_kernel_irqfd, consumer);
+	struct kvm *kvm = irqfd->kvm;
+	int ret;
+
+	WARN_ON(irqfd->producer != prod);
+
+	/*
+	 * If the producer of an IRQ that is currently being posted to a vCPU
+	 * is unregistered, change the associated IRTE back to remapped mode as
+	 * the IRQ has been released (or repurposed) by the device driver, i.e.
+	 * KVM must relinquish control of the IRTE.
+	 */
+	spin_lock_irq(&kvm->irqfds.lock);
+	irqfd->producer = NULL;
+
+	if (irqfd->irq_entry.type == KVM_IRQ_ROUTING_MSI) {
+		ret = kvm_x86_call(pi_update_irte)(irqfd, irqfd->kvm, prod->irq,
+						   irqfd->gsi, NULL);
+		if (ret)
+			pr_info("irq bypass consumer (eventfd %p) unregistration fails: %d\n",
+				irqfd->consumer.eventfd, ret);
+	}
+
+	spin_unlock_irq(&kvm->irqfds.lock);
+
+
+	kvm_arch_end_assignment(irqfd->kvm);
+}
+
+int kvm_arch_update_irqfd_routing(struct kvm_kernel_irqfd *irqfd,
+				  struct kvm_kernel_irq_routing_entry *old,
+				  struct kvm_kernel_irq_routing_entry *new)
+{
+	return kvm_x86_call(pi_update_irte)(irqfd, irqfd->kvm, irqfd->producer->irq,
+					    irqfd->gsi, 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;
+
+	return !!memcmp(&old->msi, &new->msi, sizeof(new->msi));
+}
+
 #ifdef CONFIG_KVM_IOAPIC
 #define IOAPIC_ROUTING_ENTRY(irq) \
 	{ .gsi = irq, .type = KVM_IRQ_ROUTING_IRQCHIP,	\

arch/x86/kvm/x86.c

@@ -6420,18 +6420,6 @@ void kvm_arch_sync_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot)
 		kvm_vcpu_kick(vcpu);
 }
 
-int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_event,
-			bool line_status)
-{
-	if (!irqchip_in_kernel(kvm))
-		return -ENXIO;
-
-	irq_event->status = kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID,
-					irq_event->irq, irq_event->level,
-					line_status);
-	return 0;
-}
-
 int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
 			    struct kvm_enable_cap *cap)
 {
@@ -13504,81 +13492,6 @@ bool kvm_arch_has_noncoherent_dma(struct kvm *kvm)
 }
 EXPORT_SYMBOL_GPL(kvm_arch_has_noncoherent_dma);
 
-int kvm_arch_irq_bypass_add_producer(struct irq_bypass_consumer *cons,
-				      struct irq_bypass_producer *prod)
-{
-	struct kvm_kernel_irqfd *irqfd =
-		container_of(cons, struct kvm_kernel_irqfd, consumer);
-	struct kvm *kvm = irqfd->kvm;
-	int ret = 0;
-
-	kvm_arch_start_assignment(irqfd->kvm);
-
-	spin_lock_irq(&kvm->irqfds.lock);
-	irqfd->producer = prod;
-
-	if (irqfd->irq_entry.type == KVM_IRQ_ROUTING_MSI) {
-		ret = kvm_x86_call(pi_update_irte)(irqfd, irqfd->kvm, prod->irq,
-						   irqfd->gsi, &irqfd->irq_entry);
-		if (ret)
-			kvm_arch_end_assignment(irqfd->kvm);
-	}
-	spin_unlock_irq(&kvm->irqfds.lock);
-
-	return ret;
-}
-
-void kvm_arch_irq_bypass_del_producer(struct irq_bypass_consumer *cons,
-				      struct irq_bypass_producer *prod)
-{
-	struct kvm_kernel_irqfd *irqfd =
-		container_of(cons, struct kvm_kernel_irqfd, consumer);
-	struct kvm *kvm = irqfd->kvm;
-	int ret;
-
-	WARN_ON(irqfd->producer != prod);
-
-	/*
-	 * When producer of consumer is unregistered, we change back to
-	 * remapped mode, so we can re-use the current implementation
-	 * when the irq is masked/disabled or the consumer side (KVM
-	 * int this case doesn't want to receive the interrupts.
-	*/
-	spin_lock_irq(&kvm->irqfds.lock);
-	irqfd->producer = NULL;
-
-	if (irqfd->irq_entry.type == KVM_IRQ_ROUTING_MSI) {
-		ret = kvm_x86_call(pi_update_irte)(irqfd, irqfd->kvm, prod->irq,
-						   irqfd->gsi, NULL);
-		if (ret)
-			pr_info("irq bypass consumer (eventfd %p) unregistration fails: %d\n",
-				irqfd->consumer.eventfd, ret);
-	}
-
-	spin_unlock_irq(&kvm->irqfds.lock);
-
-
-	kvm_arch_end_assignment(irqfd->kvm);
-}
-
-int kvm_arch_update_irqfd_routing(struct kvm_kernel_irqfd *irqfd,
-				  struct kvm_kernel_irq_routing_entry *old,
-				  struct kvm_kernel_irq_routing_entry *new)
-{
-	return kvm_x86_call(pi_update_irte)(irqfd, irqfd->kvm, irqfd->producer->irq,
-					    irqfd->gsi, 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;
-
-	return !!memcmp(&old->msi, &new->msi, sizeof(new->msi));
-}
-
 bool kvm_vector_hashing_enabled(void)
 {
 	return vector_hashing;