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Commit 1b6c0168 authored by Avi Kivity's avatar Avi Kivity
Browse files

KVM: Keep track of which cpus have virtualization enabled 



By keeping track of which cpus have virtualization enabled, we
prevent double-enable or double-disable during hotplug, which is a
very fatal oops.

Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
parent a52b1752

drivers/kvm/kvm_main.c

+33 −12
Original line number Diff line number Diff line
@@ -50,8 +50,12 @@ MODULE_LICENSE("GPL"); 
static DEFINE_SPINLOCK(kvm_lock);

static LIST_HEAD(vm_list);



static cpumask_t cpus_hardware_enabled;



struct kvm_arch_ops *kvm_arch_ops;



static void hardware_disable(void *ignored);



#define STAT_OFFSET(x) offsetof(struct kvm_vcpu, stat.x)



static struct kvm_stats_debugfs_item {
@@ -2930,7 +2934,7 @@ static int kvm_reboot(struct notifier_block *notifier, unsigned long val, 
		 * in vmx root mode.

		 */

		printk(KERN_INFO "kvm: exiting hardware virtualization\n");

		on_each_cpu(kvm_arch_ops->hardware_disable, NULL, 0, 1);

		on_each_cpu(hardware_disable, NULL, 0, 1);

	}

	return NOTIFY_OK;

}
@@ -2973,6 +2977,27 @@ static void decache_vcpus_on_cpu(int cpu) 
	spin_unlock(&kvm_lock);

}



static void hardware_enable(void *junk)

{

	int cpu = raw_smp_processor_id();



	if (cpu_isset(cpu, cpus_hardware_enabled))

		return;

	cpu_set(cpu, cpus_hardware_enabled);

	kvm_arch_ops->hardware_enable(NULL);

}



static void hardware_disable(void *junk)

{

	int cpu = raw_smp_processor_id();



	if (!cpu_isset(cpu, cpus_hardware_enabled))

		return;

	cpu_clear(cpu, cpus_hardware_enabled);

	decache_vcpus_on_cpu(cpu);

	kvm_arch_ops->hardware_disable(NULL);

}



static int kvm_cpu_hotplug(struct notifier_block *notifier, unsigned long val,

			   void *v)

{
@@ -2985,16 +3010,13 @@ static int kvm_cpu_hotplug(struct notifier_block *notifier, unsigned long val, 
	case CPU_UP_CANCELED_FROZEN:

		printk(KERN_INFO "kvm: disabling virtualization on CPU%d\n",

		       cpu);

		decache_vcpus_on_cpu(cpu);

		smp_call_function_single(cpu, kvm_arch_ops->hardware_disable,

					 NULL, 0, 1);

		smp_call_function_single(cpu, hardware_disable, NULL, 0, 1);

		break;

	case CPU_ONLINE:

	case CPU_ONLINE_FROZEN:

		printk(KERN_INFO "kvm: enabling virtualization on CPU%d\n",

		       cpu);

		smp_call_function_single(cpu, kvm_arch_ops->hardware_enable,

					 NULL, 0, 1);

		smp_call_function_single(cpu, hardware_enable, NULL, 0, 1);

		break;

	}

	return NOTIFY_OK;
@@ -3088,14 +3110,13 @@ static void kvm_exit_debug(void) 


static int kvm_suspend(struct sys_device *dev, pm_message_t state)

{

	decache_vcpus_on_cpu(raw_smp_processor_id());

	on_each_cpu(kvm_arch_ops->hardware_disable, NULL, 0, 1);

	on_each_cpu(hardware_disable, NULL, 0, 0);

	return 0;

}



static int kvm_resume(struct sys_device *dev)

{

	on_each_cpu(kvm_arch_ops->hardware_enable, NULL, 0, 1);

	on_each_cpu(hardware_disable, NULL, 0, 0);

	return 0;

}
@@ -3136,7 +3157,7 @@ int kvm_init_arch(struct kvm_arch_ops *ops, struct module *module) 
	if (r < 0)

		goto out;



	on_each_cpu(kvm_arch_ops->hardware_enable, NULL, 0, 1);

	on_each_cpu(hardware_enable, NULL, 0, 1);

	r = register_cpu_notifier(&kvm_cpu_notifier);

	if (r)

		goto out_free_1;
@@ -3168,7 +3189,7 @@ int kvm_init_arch(struct kvm_arch_ops *ops, struct module *module) 
	unregister_reboot_notifier(&kvm_reboot_notifier);

	unregister_cpu_notifier(&kvm_cpu_notifier);

out_free_1:

	on_each_cpu(kvm_arch_ops->hardware_disable, NULL, 0, 1);

	on_each_cpu(hardware_disable, NULL, 0, 1);

	kvm_arch_ops->hardware_unsetup();

out:

	kvm_arch_ops = NULL;
@@ -3182,7 +3203,7 @@ void kvm_exit_arch(void) 
	sysdev_class_unregister(&kvm_sysdev_class);

	unregister_reboot_notifier(&kvm_reboot_notifier);

	unregister_cpu_notifier(&kvm_cpu_notifier);

	on_each_cpu(kvm_arch_ops->hardware_disable, NULL, 0, 1);

	on_each_cpu(hardware_disable, NULL, 0, 1);

	kvm_arch_ops->hardware_unsetup();

	kvm_arch_ops = NULL;

}