Commit d68d82af authored by Alex Nixon's avatar Alex Nixon Committed by Ingo Molnar
Browse files

xen: implement CPU hotplugging 



Note the changes from 2.6.18-xen CPU hotplugging:

A vcpu_down request from the remote admin via Xenbus both hotunplugs the
CPU, and disables it by removing it from the cpu_present map, and removing
its entry in /sys.

A vcpu_up request from the remote admin only re-enables the CPU, and does
not immediately bring the CPU up. A udev event is emitted, which can be
caught by the user if he wishes to automatically re-up CPUs when available,
or implement a more complex policy.

Signed-off-by: default avatarAlex Nixon <alex.nixon@citrix.com>
Acked-by: default avatarJeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 8227dce7

arch/x86/xen/smp.c

+48 −12
Original line number Diff line number Diff line
@@ -11,8 +11,6 @@ 
 * useful topology information for the kernel to make use of.  As a

 * result, all CPUs are treated as if they're single-core and

 * single-threaded.

 *

 * This does not handle HOTPLUG_CPU yet.

 */

#include <linux/sched.h>

#include <linux/err.h>
@@ -61,11 +59,12 @@ static irqreturn_t xen_reschedule_interrupt(int irq, void *dev_id) 
	return IRQ_HANDLED;

}



static __cpuinit void cpu_bringup_and_idle(void)

static __cpuinit void cpu_bringup(void)

{

	int cpu = smp_processor_id();



	cpu_init();

	touch_softlockup_watchdog();

	preempt_disable();



	xen_enable_sysenter();
@@ -86,6 +85,11 @@ static __cpuinit void cpu_bringup_and_idle(void) 
	local_irq_enable();



	wmb();			/* make sure everything is out */

}



static __cpuinit void cpu_bringup_and_idle(void)

{

	cpu_bringup();

	cpu_idle();

}
@@ -209,8 +213,6 @@ static void __init xen_smp_prepare_cpus(unsigned int max_cpus) 


		cpu_set(cpu, cpu_present_map);

	}



	//init_xenbus_allowed_cpumask();

}



static __cpuinit int
@@ -278,12 +280,6 @@ static int __cpuinit xen_cpu_up(unsigned int cpu) 
	struct task_struct *idle = idle_task(cpu);

	int rc;



#if 0

	rc = cpu_up_check(cpu);

	if (rc)

		return rc;

#endif



#ifdef CONFIG_X86_64

	/* Allocate node local memory for AP pdas */

	WARN_ON(cpu == 0);
@@ -336,6 +332,42 @@ static void xen_smp_cpus_done(unsigned int max_cpus) 
{

}



int xen_cpu_disable(void)

{

	unsigned int cpu = smp_processor_id();

	if (cpu == 0)

		return -EBUSY;



	cpu_disable_common();



	load_cr3(swapper_pg_dir);

	return 0;

}



void xen_cpu_die(unsigned int cpu)

{

	while (HYPERVISOR_vcpu_op(VCPUOP_is_up, cpu, NULL)) {

		current->state = TASK_UNINTERRUPTIBLE;

		schedule_timeout(HZ/10);

	}

	unbind_from_irqhandler(per_cpu(resched_irq, cpu), NULL);

	unbind_from_irqhandler(per_cpu(callfunc_irq, cpu), NULL);

	unbind_from_irqhandler(per_cpu(debug_irq, cpu), NULL);

	unbind_from_irqhandler(per_cpu(callfuncsingle_irq, cpu), NULL);

	xen_uninit_lock_cpu(cpu);

	xen_teardown_timer(cpu);



	if (num_online_cpus() == 1)

		alternatives_smp_switch(0);

}



void xen_play_dead(void)

{

	play_dead_common();

	HYPERVISOR_vcpu_op(VCPUOP_down, smp_processor_id(), NULL);

	cpu_bringup();

}



static void stop_self(void *v)

{

	int cpu = smp_processor_id();
@@ -419,9 +451,13 @@ static irqreturn_t xen_call_function_single_interrupt(int irq, void *dev_id) 
static const struct smp_ops xen_smp_ops __initdata = {

	.smp_prepare_boot_cpu = xen_smp_prepare_boot_cpu,

	.smp_prepare_cpus = xen_smp_prepare_cpus,

	.cpu_up = xen_cpu_up,

	.smp_cpus_done = xen_smp_cpus_done,



	.cpu_up = xen_cpu_up,

	.cpu_die = xen_cpu_die,

	.cpu_disable = xen_cpu_disable,

	.play_dead = xen_play_dead,



	.smp_send_stop = xen_smp_send_stop,

	.smp_send_reschedule = xen_smp_send_reschedule,

arch/x86/xen/spinlock.c

+5 −0
Original line number Diff line number Diff line
@@ -357,6 +357,11 @@ void __cpuinit xen_init_lock_cpu(int cpu) 
	printk("cpu %d spinlock event irq %d\n", cpu, irq);

}



void xen_uninit_lock_cpu(int cpu)

{

	unbind_from_irqhandler(per_cpu(lock_kicker_irq, cpu), NULL);

}



void __init xen_init_spinlocks(void)

{

	pv_lock_ops.spin_is_locked = xen_spin_is_locked;

arch/x86/xen/time.c

+8 −0
Original line number Diff line number Diff line
@@ -450,6 +450,14 @@ void xen_setup_timer(int cpu) 
	setup_runstate_info(cpu);

}



void xen_teardown_timer(int cpu)

{

	struct clock_event_device *evt;

	BUG_ON(cpu == 0);

	evt = &per_cpu(xen_clock_events, cpu);

	unbind_from_irqhandler(evt->irq, NULL);

}



void xen_setup_cpu_clockevents(void)

{

	BUG_ON(preemptible());

arch/x86/xen/xen-ops.h

+6 −0
Original line number Diff line number Diff line
@@ -34,6 +34,7 @@ void __init xen_build_dynamic_phys_to_machine(void); 


void xen_init_irq_ops(void);

void xen_setup_timer(int cpu);

void xen_teardown_timer(int cpu);

cycle_t xen_clocksource_read(void);

void xen_setup_cpu_clockevents(void);

unsigned long xen_tsc_khz(void);
@@ -50,11 +51,16 @@ void xen_mark_init_mm_pinned(void); 


void __init xen_setup_vcpu_info_placement(void);



void xen_play_dead(void);

void xen_cpu_die(unsigned int cpu);

int xen_cpu_disable(void);



#ifdef CONFIG_SMP

void xen_smp_init(void);



void __init xen_init_spinlocks(void);

__cpuinit void xen_init_lock_cpu(int cpu);

void xen_uninit_lock_cpu(int cpu);



extern cpumask_t xen_cpu_initialized_map;

#else

drivers/xen/Makefile

+1 −1
Original line number Diff line number Diff line 
obj-y	+= grant-table.o features.o events.o manage.o

obj-y	+= grant-table.o features.o events.o manage.o cpu_hotplug.o

obj-y	+= xenbus/

obj-$(CONFIG_XEN_XENCOMM)	+= xencomm.o

obj-$(CONFIG_XEN_BALLOON)	+= balloon.o

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