KVM: Use syscore_ops instead of sysdev class and sysdev

KVM uses a sysdev class and a sysdev for executing kvm_suspend()
after interrupts have been turned off on the boot CPU (during system
suspend) and for executing kvm_resume() before turning on interrupts
on the boot CPU (during system resume). However, since both of these
functions ignore their arguments, the entire mechanism may be
replaced with a struct syscore_ops object which is simpler.

Signed-off-by: Rafael J. Wysocki <[e-mail]>
Acked-by: Avi Kivity <[e-mail]>

virt/kvm/kvm_main.c

···
 #include <linux/debugfs.h>
 #include <linux/highmem.h>
 #include <linux/file.h>
-#include <linux/sysdev.h>
+#include <linux/syscore_ops.h>
 #include <linux/cpu.h>
 #include <linux/sched.h>
 #include <linux/cpumask.h>
···
 	debugfs_remove(kvm_debugfs_dir);
 }
 
-static int kvm_suspend(struct sys_device *dev, pm_message_t state)
+static int kvm_suspend(void)
 {
 	if (kvm_usage_count)
 		hardware_disable_nolock(NULL);
 	return 0;
 }
 
-static int kvm_resume(struct sys_device *dev)
+static void kvm_resume(void)
 {
 	if (kvm_usage_count) {
 		WARN_ON(raw_spin_is_locked(&kvm_lock));
 		hardware_enable_nolock(NULL);
 	}
-	return 0;
 }
 
-static struct sysdev_class kvm_sysdev_class = {
-	.name = "kvm",
+static struct syscore_ops kvm_syscore_ops = {
 	.suspend = kvm_suspend,
 	.resume = kvm_resume,
-};
-
-static struct sys_device kvm_sysdev = {
-	.id = 0,
-	.cls = &kvm_sysdev_class,
 };
 
 struct page *bad_page;
···
 		goto out_free_2;
 	register_reboot_notifier(&kvm_reboot_notifier);
 
-	r = sysdev_class_register(&kvm_sysdev_class);
-	if (r)
-		goto out_free_3;
-
-	r = sysdev_register(&kvm_sysdev);
-	if (r)
-		goto out_free_4;
-
 	/* A kmem cache lets us meet the alignment requirements of fx_save. */
 	if (!vcpu_align)
 		vcpu_align = __alignof__(struct kvm_vcpu);
···
 					   0, NULL);
 	if (!kvm_vcpu_cache) {
 		r = -ENOMEM;
-		goto out_free_5;
+		goto out_free_3;
 	}
 
 	r = kvm_async_pf_init();
···
 		goto out_unreg;
 	}
 
+	register_syscore_ops(&kvm_syscore_ops);
+
 	kvm_preempt_ops.sched_in = kvm_sched_in;
 	kvm_preempt_ops.sched_out = kvm_sched_out;
 
···
 	kvm_async_pf_deinit();
 out_free:
 	kmem_cache_destroy(kvm_vcpu_cache);
-out_free_5:
-	sysdev_unregister(&kvm_sysdev);
-out_free_4:
-	sysdev_class_unregister(&kvm_sysdev_class);
 out_free_3:
 	unregister_reboot_notifier(&kvm_reboot_notifier);
 	unregister_cpu_notifier(&kvm_cpu_notifier);
···
 	misc_deregister(&kvm_dev);
 	kmem_cache_destroy(kvm_vcpu_cache);
 	kvm_async_pf_deinit();
-	sysdev_unregister(&kvm_sysdev);
-	sysdev_class_unregister(&kvm_sysdev_class);
+	unregister_syscore_ops(&kvm_syscore_ops);
 	unregister_reboot_notifier(&kvm_reboot_notifier);
 	unregister_cpu_notifier(&kvm_cpu_notifier);
 	on_each_cpu(hardware_disable_nolock, NULL, 1);