Revert "kvm: detect assigned device via irqbypass manager"

Now that KVM explicitly tracks the number of possible bypass IRQs, and
doesn't conflate IRQ bypass with host MMIO access, stop bumping the
assigned device count when adding an IRQ bypass producer.

This reverts commit 2edd9cb.

Link: https://lore.kernel.org/r/20250523011756.3243624-5-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Author: sean-jc

arch/x86/kvm/irq.c

@@ -565,8 +565,6 @@ int kvm_arch_irq_bypass_add_producer(struct irq_bypass_consumer *cons,
 	struct kvm *kvm = irqfd->kvm;
 	int ret = 0;
 
-	kvm_arch_start_assignment(irqfd->kvm);
-
 	spin_lock_irq(&kvm->irqfds.lock);
 	irqfd->producer = prod;
 
@@ -575,10 +573,8 @@ int kvm_arch_irq_bypass_add_producer(struct irq_bypass_consumer *cons,
 
 	if (irqfd->irq_entry.type == KVM_IRQ_ROUTING_MSI) {
 		ret = kvm_pi_update_irte(irqfd, &irqfd->irq_entry);
-		if (ret) {
+		if (ret)
 			kvm->arch.nr_possible_bypass_irqs--;
-			kvm_arch_end_assignment(irqfd->kvm);
-		}
 	}
 	spin_unlock_irq(&kvm->irqfds.lock);
 
@@ -614,9 +610,6 @@ void kvm_arch_irq_bypass_del_producer(struct irq_bypass_consumer *cons,
 	kvm->arch.nr_possible_bypass_irqs--;
 
 	spin_unlock_irq(&kvm->irqfds.lock);
-
-
-	kvm_arch_end_assignment(irqfd->kvm);
 }
 
 void kvm_arch_update_irqfd_routing(struct kvm_kernel_irqfd *irqfd,