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Commit 4761adb6 authored by Richard Cochran's avatar Richard Cochran Committed by Ingo Molnar
Browse files

arm/xen: Convert to hotplug state machine 



Install the callbacks via the state machine and let the core invoke
the callbacks on the already online CPUs.

The get_cpu() in xen_starting_cpu() boils down to preempt_disable() since
we already know the CPU we run on. Disabling preemption shouldn't be required
here from what I see since it we don't switch CPUs while invoking the function.

Signed-off-by: default avatarRichard Cochran <rcochran@linutronix.de>
Signed-off-by: default avatarAnna-Maria Gleixner <anna-maria@linutronix.de>
Reviewed-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: default avatarStefano Stabellini <sstabellini@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arm-kernel@lists.infradead.org
Cc: rt@linutronix.de
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/20160713153336.971559670@linutronix.de


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 26b87688

arch/arm/xen/enlighten.c

+11 −30
Original line number Diff line number Diff line
@@ -161,12 +161,11 @@ static struct notifier_block xen_pvclock_gtod_notifier = { 
	.notifier_call = xen_pvclock_gtod_notify,

};



static void xen_percpu_init(void)

static int xen_starting_cpu(unsigned int cpu)

{

	struct vcpu_register_vcpu_info info;

	struct vcpu_info *vcpup;

	int err;

	int cpu = get_cpu();



	/* 

	 * VCPUOP_register_vcpu_info cannot be called twice for the same
@@ -190,7 +189,13 @@ static void xen_percpu_init(void) 


after_register_vcpu_info:

	enable_percpu_irq(xen_events_irq, 0);

	put_cpu();

	return 0;

}



static int xen_dying_cpu(unsigned int cpu)

{

	disable_percpu_irq(xen_events_irq);

	return 0;

}



static void xen_restart(enum reboot_mode reboot_mode, const char *cmd)
@@ -209,28 +214,6 @@ static void xen_power_off(void) 
	BUG_ON(rc);

}



static int xen_cpu_notification(struct notifier_block *self,

				unsigned long action,

				void *hcpu)

{

	switch (action) {

	case CPU_STARTING:

		xen_percpu_init();

		break;

	case CPU_DYING:

		disable_percpu_irq(xen_events_irq);

		break;

	default:

		break;

	}



	return NOTIFY_OK;

}



static struct notifier_block xen_cpu_notifier = {

	.notifier_call = xen_cpu_notification,

};



static irqreturn_t xen_arm_callback(int irq, void *arg)

{

	xen_hvm_evtchn_do_upcall();
@@ -351,16 +334,14 @@ static int __init xen_guest_init(void) 
		return -EINVAL;

	}



	xen_percpu_init();



	register_cpu_notifier(&xen_cpu_notifier);



	pv_time_ops.steal_clock = xen_stolen_accounting;

	static_key_slow_inc(&paravirt_steal_enabled);

	if (xen_initial_domain())

		pvclock_gtod_register_notifier(&xen_pvclock_gtod_notifier);



	return 0;

	return cpuhp_setup_state(CPUHP_AP_ARM_XEN_STARTING,

				 "AP_ARM_XEN_STARTING", xen_starting_cpu,

				 xen_dying_cpu);

}

early_initcall(xen_guest_init);

include/linux/cpuhotplug.h

+1 −0
Original line number Diff line number Diff line
@@ -47,6 +47,7 @@ enum cpuhp_state { 
	CPUHP_AP_KVM_STARTING,

	CPUHP_AP_KVM_ARM_VGIC_STARTING,

	CPUHP_AP_KVM_ARM_TIMER_STARTING,

	CPUHP_AP_ARM_XEN_STARTING,

	CPUHP_AP_LEDTRIG_STARTING,

	CPUHP_AP_NOTIFY_STARTING,

	CPUHP_AP_ONLINE,