KVM: Unset kvm_arch_ops if arch module loading failed

Otherwise, the core module thinks the arch module is loaded, and won't
let you reload it after you've fixed the bug.
Signed-off-by: Avi Kivity <avi@qumranet.com>

drivers/kvm/kvm_main.c

@@ -2464,7 +2464,7 @@ int kvm_init_arch(struct kvm_arch_ops *ops, struct module *module)
 
 	r = kvm_arch_ops->hardware_setup();
 	if (r < 0)
-	    return r;
+		goto out;
 
 	on_each_cpu(kvm_arch_ops->hardware_enable, NULL, 0, 1);
 	r = register_cpu_notifier(&kvm_cpu_notifier);
@@ -2500,6 +2500,8 @@ int kvm_init_arch(struct kvm_arch_ops *ops, struct module *module)
 out_free_1:
 	on_each_cpu(kvm_arch_ops->hardware_disable, NULL, 0, 1);
 	kvm_arch_ops->hardware_unsetup();
+out:
+	kvm_arch_ops = NULL;
 	return r;
 }