Commit 9a20ea4b authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Thomas Gleixner
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x86/kvm: Convert to hotplug state machine 



Install the callbacks via the state machine. The online & down callbacks are
invoked on the target CPU so we can avoid using smp_call_function_single().
local_irq_disable() is used because smp_call_function_single() used to invoke
the function with interrupts disabled.

Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160818125731.27256-15-bigeasy@linutronix.de


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent e8483b57

arch/x86/kernel/kvm.c

+16 −27
Original line number Diff line number Diff line
@@ -423,12 +423,7 @@ static void __init kvm_smp_prepare_boot_cpu(void) 
	kvm_spinlock_init();

}



static void kvm_guest_cpu_online(void *dummy)

{

	kvm_guest_cpu_init();

}



static void kvm_guest_cpu_offline(void *dummy)

static void kvm_guest_cpu_offline(void)

{

	kvm_disable_steal_time();

	if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
@@ -437,29 +432,21 @@ static void kvm_guest_cpu_offline(void *dummy) 
	apf_task_wake_all();

}



static int kvm_cpu_notify(struct notifier_block *self, unsigned long action,

			  void *hcpu)

static int kvm_cpu_online(unsigned int cpu)

{

	int cpu = (unsigned long)hcpu;

	switch (action) {

	case CPU_ONLINE:

	case CPU_DOWN_FAILED:

	case CPU_ONLINE_FROZEN:

		smp_call_function_single(cpu, kvm_guest_cpu_online, NULL, 0);

		break;

	case CPU_DOWN_PREPARE:

	case CPU_DOWN_PREPARE_FROZEN:

		smp_call_function_single(cpu, kvm_guest_cpu_offline, NULL, 1);

		break;

	default:

		break;

	}

	return NOTIFY_OK;

	local_irq_disable();

	kvm_guest_cpu_init();

	local_irq_enable();

	return 0;

}



static struct notifier_block kvm_cpu_notifier = {

        .notifier_call  = kvm_cpu_notify,

};

static int kvm_cpu_down_prepare(unsigned int cpu)

{

	local_irq_disable();

	kvm_guest_cpu_offline();

	local_irq_enable();

	return 0;

}

#endif



static void __init kvm_apf_trap_init(void)
@@ -494,7 +481,9 @@ void __init kvm_guest_init(void) 


#ifdef CONFIG_SMP

	smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;

	register_cpu_notifier(&kvm_cpu_notifier);

	if (cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/kvm:online",

				      kvm_cpu_online, kvm_cpu_down_prepare) < 0)

		pr_err("kvm_guest: Failed to install cpu hotplug callbacks\n");

#else

	kvm_guest_cpu_init();

#endif

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