KVM: arm64: vgic: Ensure that slots_lock is held in vgic_register_all_redist_iodevs()

Although we implicitly depend on slots_lock being held when registering
IO devices with the IO bus infrastructure, we don't enforce this
requirement. Make it explicit.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20231207151201.3028710-5-maz@kernel.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>

Author: Marc Zyngier

arch/arm64/kvm/vgic/vgic-mmio-v3.c

@@ -833,6 +833,8 @@ static int vgic_register_all_redist_iodevs(struct kvm *kvm)
 	unsigned long c;
 	int ret = 0;
 
+	lockdep_assert_held(&kvm->slots_lock);
+
 	kvm_for_each_vcpu(c, vcpu, kvm) {
 		ret = vgic_register_redist_iodev(vcpu);
 		if (ret)