arch/x86/xen/smp.c - fp2-dev/kernel/msm - Gitiles

 /*
  * Xen SMP support
  *
  * This file implements the Xen versions of smp_ops.  SMP under Xen is
  * very straightforward.  Bringing a CPU up is simply a matter of
  * loading its initial context and setting it running.
  *
  * IPIs are handled through the Xen event mechanism.
  *
  * Because virtual CPUs can be scheduled onto any real CPU, there's no
  * 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>
 #include <linux/smp.h>

 #include <asm/paravirt.h>
 #include <asm/desc.h>
 #include <asm/pgtable.h>
 #include <asm/cpu.h>

 #include <xen/interface/xen.h>
 #include <xen/interface/vcpu.h>

 #include <asm/xen/interface.h>
 #include <asm/xen/hypercall.h>

 #include <xen/page.h>
 #include <xen/events.h>

 #include "xen-ops.h"
 #include "mmu.h"

 cpumask_t xen_cpu_initialized_map;
 static DEFINE_PER_CPU(int, resched_irq) = -1;
 static DEFINE_PER_CPU(int, callfunc_irq) = -1;
 static DEFINE_PER_CPU(int, debug_irq) = -1;

 /*
  * Structure and data for smp_call_function(). This is designed to minimise
  * static memory requirements. It also looks cleaner.
  */
 static DEFINE_SPINLOCK(call_lock);

 struct call_data_struct {
 	void (*func) (void *info);
 	void *info;
 	atomic_t started;
 	atomic_t finished;
 	int wait;
 };

 static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id);

 static struct call_data_struct *call_data;

 /*
  * Reschedule call back. Nothing to do,
  * all the work is done automatically when
  * we return from the interrupt.
  */
 static irqreturn_t xen_reschedule_interrupt(int irq, void *dev_id)
 {
 #ifdef CONFIG_X86_32
 	__get_cpu_var(irq_stat).irq_resched_count++;
 #else
 	add_pda(irq_resched_count, 1);
 #endif

 	return IRQ_HANDLED;
 }

 static __cpuinit void cpu_bringup_and_idle(void)
 {
 	int cpu = smp_processor_id();

 	cpu_init();
 	xen_enable_sysenter();

 	preempt_disable();
 	per_cpu(cpu_state, cpu) = CPU_ONLINE;

 	xen_setup_cpu_clockevents();

 	/* We can take interrupts now: we're officially "up". */
 	local_irq_enable();

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

 static int xen_smp_intr_init(unsigned int cpu)
 {
 	int rc;
 	const char *resched_name, *callfunc_name, *debug_name;

 	resched_name = kasprintf(GFP_KERNEL, "resched%d", cpu);
 	rc = bind_ipi_to_irqhandler(XEN_RESCHEDULE_VECTOR,
 				    cpu,
 				    xen_reschedule_interrupt,
 				    IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING,
 				    resched_name,
 				    NULL);
 	if (rc < 0)
 		goto fail;
 	per_cpu(resched_irq, cpu) = rc;

 	callfunc_name = kasprintf(GFP_KERNEL, "callfunc%d", cpu);
 	rc = bind_ipi_to_irqhandler(XEN_CALL_FUNCTION_VECTOR,
 				    cpu,
 				    xen_call_function_interrupt,
 				    IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING,
 				    callfunc_name,
 				    NULL);
 	if (rc < 0)
 		goto fail;
 	per_cpu(callfunc_irq, cpu) = rc;

 	debug_name = kasprintf(GFP_KERNEL, "debug%d", cpu);
 	rc = bind_virq_to_irqhandler(VIRQ_DEBUG, cpu, xen_debug_interrupt,
 				     IRQF_DISABLED | IRQF_PERCPU | IRQF_NOBALANCING,
 				     debug_name, NULL);
 	if (rc < 0)
 		goto fail;
 	per_cpu(debug_irq, cpu) = rc;

 	return 0;

  fail:
 	if (per_cpu(resched_irq, cpu) >= 0)
 		unbind_from_irqhandler(per_cpu(resched_irq, cpu), NULL);
 	if (per_cpu(callfunc_irq, cpu) >= 0)
 		unbind_from_irqhandler(per_cpu(callfunc_irq, cpu), NULL);
 	if (per_cpu(debug_irq, cpu) >= 0)
 		unbind_from_irqhandler(per_cpu(debug_irq, cpu), NULL);
 	return rc;
 }

 void __init xen_fill_possible_map(void)
 {
 	int i, rc;

 	for (i = 0; i < NR_CPUS; i++) {
 		rc = HYPERVISOR_vcpu_op(VCPUOP_is_up, i, NULL);
 		if (rc >= 0)
 			cpu_set(i, cpu_possible_map);
 	}
 }

 void __init xen_smp_prepare_boot_cpu(void)
 {
 	int cpu;

 	BUG_ON(smp_processor_id() != 0);
 	native_smp_prepare_boot_cpu();

 	/* We've switched to the "real" per-cpu gdt, so make sure the
 	   old memory can be recycled */
 	make_lowmem_page_readwrite(&per_cpu__gdt_page);

 	for_each_possible_cpu(cpu) {
 		cpus_clear(per_cpu(cpu_sibling_map, cpu));
 		/*
 		 * cpu_core_map lives in a per cpu area that is cleared
 		 * when the per cpu array is allocated.
 		 *
 		 * cpus_clear(per_cpu(cpu_core_map, cpu));
 		 */
 	}

 	xen_setup_vcpu_info_placement();
 }

 void __init xen_smp_prepare_cpus(unsigned int max_cpus)
 {
 	unsigned cpu;

 	for_each_possible_cpu(cpu) {
 		cpus_clear(per_cpu(cpu_sibling_map, cpu));
 		/*
 		 * cpu_core_ map will be zeroed when the per
 		 * cpu area is allocated.
 		 *
 		 * cpus_clear(per_cpu(cpu_core_map, cpu));
 		 */
 	}

 	smp_store_cpu_info(0);
 	set_cpu_sibling_map(0);

 	if (xen_smp_intr_init(0))
 		BUG();

 	xen_cpu_initialized_map = cpumask_of_cpu(0);

 	/* Restrict the possible_map according to max_cpus. */
 	while ((num_possible_cpus() > 1) && (num_possible_cpus() > max_cpus)) {
 		for (cpu = NR_CPUS - 1; !cpu_possible(cpu); cpu--)
 			continue;
 		cpu_clear(cpu, cpu_possible_map);
 	}

 	for_each_possible_cpu (cpu) {
 		struct task_struct *idle;

 		if (cpu == 0)
 			continue;

 		idle = fork_idle(cpu);
 		if (IS_ERR(idle))
 			panic("failed fork for CPU %d", cpu);

 		cpu_set(cpu, cpu_present_map);
 	}

 	//init_xenbus_allowed_cpumask();
 }

 static __cpuinit int
 cpu_initialize_context(unsigned int cpu, struct task_struct *idle)
 {
 	struct vcpu_guest_context *ctxt;
 	struct gdt_page *gdt = &per_cpu(gdt_page, cpu);

 	if (cpu_test_and_set(cpu, xen_cpu_initialized_map))
 		return 0;

 	ctxt = kzalloc(sizeof(*ctxt), GFP_KERNEL);
 	if (ctxt == NULL)
 		return -ENOMEM;

 	ctxt->flags = VGCF_IN_KERNEL;
 	ctxt->user_regs.ds = __USER_DS;
 	ctxt->user_regs.es = __USER_DS;
 	ctxt->user_regs.fs = __KERNEL_PERCPU;
 	ctxt->user_regs.gs = 0;
 	ctxt->user_regs.ss = __KERNEL_DS;
 	ctxt->user_regs.eip = (unsigned long)cpu_bringup_and_idle;
 	ctxt->user_regs.eflags = 0x1000; /* IOPL_RING1 */

 	memset(&ctxt->fpu_ctxt, 0, sizeof(ctxt->fpu_ctxt));

 	xen_copy_trap_info(ctxt->trap_ctxt);

 	ctxt->ldt_ents = 0;

 	BUG_ON((unsigned long)gdt->gdt & ~PAGE_MASK);
 	make_lowmem_page_readonly(gdt->gdt);

 	ctxt->gdt_frames[0] = virt_to_mfn(gdt->gdt);
 	ctxt->gdt_ents      = ARRAY_SIZE(gdt->gdt);

 	ctxt->user_regs.cs = __KERNEL_CS;
 	ctxt->user_regs.esp = idle->thread.sp0 - sizeof(struct pt_regs);

 	ctxt->kernel_ss = __KERNEL_DS;
 	ctxt->kernel_sp = idle->thread.sp0;

 	ctxt->event_callback_cs     = __KERNEL_CS;
 	ctxt->event_callback_eip    = (unsigned long)xen_hypervisor_callback;
 	ctxt->failsafe_callback_cs  = __KERNEL_CS;
 	ctxt->failsafe_callback_eip = (unsigned long)xen_failsafe_callback;

 	per_cpu(xen_cr3, cpu) = __pa(swapper_pg_dir);
 	ctxt->ctrlreg[3] = xen_pfn_to_cr3(virt_to_mfn(swapper_pg_dir));

 	if (HYPERVISOR_vcpu_op(VCPUOP_initialise, cpu, ctxt))
 		BUG();

 	kfree(ctxt);
 	return 0;
 }

 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

 	init_gdt(cpu);
 	per_cpu(current_task, cpu) = idle;
 	irq_ctx_init(cpu);
 	xen_setup_timer(cpu);

 	/* make sure interrupts start blocked */
 	per_cpu(xen_vcpu, cpu)->evtchn_upcall_mask = 1;

 	rc = cpu_initialize_context(cpu, idle);
 	if (rc)
 		return rc;

 	if (num_online_cpus() == 1)
 		alternatives_smp_switch(1);

 	rc = xen_smp_intr_init(cpu);
 	if (rc)
 		return rc;

 	smp_store_cpu_info(cpu);
 	set_cpu_sibling_map(cpu);
 	/* This must be done before setting cpu_online_map */
 	wmb();

 	cpu_set(cpu, cpu_online_map);

 	rc = HYPERVISOR_vcpu_op(VCPUOP_up, cpu, NULL);
 	BUG_ON(rc);

 	return 0;
 }

 void xen_smp_cpus_done(unsigned int max_cpus)
 {
 }

 static void stop_self(void *v)
 {
 	int cpu = smp_processor_id();

 	/* make sure we're not pinning something down */
 	load_cr3(swapper_pg_dir);
 	/* should set up a minimal gdt */

 	HYPERVISOR_vcpu_op(VCPUOP_down, cpu, NULL);
 	BUG();
 }

 void xen_smp_send_stop(void)
 {
 	smp_call_function(stop_self, NULL, 0, 0);
 }

 void xen_smp_send_reschedule(int cpu)
 {
 	xen_send_IPI_one(cpu, XEN_RESCHEDULE_VECTOR);
 }


 static void xen_send_IPI_mask(cpumask_t mask, enum ipi_vector vector)
 {
 	unsigned cpu;

 	cpus_and(mask, mask, cpu_online_map);

 	for_each_cpu_mask(cpu, mask)
 		xen_send_IPI_one(cpu, vector);
 }

 static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id)
 {
 	void (*func) (void *info) = call_data->func;
 	void *info = call_data->info;
 	int wait = call_data->wait;

 	/*
 	 * Notify initiating CPU that I've grabbed the data and am
 	 * about to execute the function
 	 */
 	mb();
 	atomic_inc(&call_data->started);
 	/*
 	 * At this point the info structure may be out of scope unless wait==1
 	 */
 	irq_enter();
 	(*func)(info);
 	__get_cpu_var(irq_stat).irq_call_count++;
 	irq_exit();

 	if (wait) {
 		mb();		/* commit everything before setting finished */
 		atomic_inc(&call_data->finished);
 	}

 	return IRQ_HANDLED;
 }

 int xen_smp_call_function_mask(cpumask_t mask, void (*func)(void *),
 			       void *info, int wait)
 {
 	struct call_data_struct data;
 	int cpus, cpu;
 	bool yield;

 	/* Holding any lock stops cpus from going down. */
 	spin_lock(&call_lock);

 	cpu_clear(smp_processor_id(), mask);

 	cpus = cpus_weight(mask);
 	if (!cpus) {
 		spin_unlock(&call_lock);
 		return 0;
 	}

 	/* Can deadlock when called with interrupts disabled */
 	WARN_ON(irqs_disabled());

 	data.func = func;
 	data.info = info;
 	atomic_set(&data.started, 0);
 	data.wait = wait;
 	if (wait)
 		atomic_set(&data.finished, 0);

 	call_data = &data;
 	mb();			/* write everything before IPI */

 	/* Send a message to other CPUs and wait for them to respond */
 	xen_send_IPI_mask(mask, XEN_CALL_FUNCTION_VECTOR);

 	/* Make sure other vcpus get a chance to run if they need to. */
 	yield = false;
 	for_each_cpu_mask(cpu, mask)
 		if (xen_vcpu_stolen(cpu))
 			yield = true;

 	if (yield)
 		HYPERVISOR_sched_op(SCHEDOP_yield, 0);

 	/* Wait for response */
 	while (atomic_read(&data.started) != cpus ||
 	       (wait && atomic_read(&data.finished) != cpus))
 		cpu_relax();

 	spin_unlock(&call_lock);

 	return 0;
 }
	/*
	* Xen SMP support
	*
	* This file implements the Xen versions of smp_ops. SMP under Xen is
	* very straightforward. Bringing a CPU up is simply a matter of
	* loading its initial context and setting it running.
	*
	* IPIs are handled through the Xen event mechanism.
	*
	* Because virtual CPUs can be scheduled onto any real CPU, there's no
	* 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>
	#include <linux/smp.h>

	#include <asm/paravirt.h>
	#include <asm/desc.h>
	#include <asm/pgtable.h>
	#include <asm/cpu.h>

	#include <xen/interface/xen.h>
	#include <xen/interface/vcpu.h>

	#include <asm/xen/interface.h>
	#include <asm/xen/hypercall.h>

	#include <xen/page.h>
	#include <xen/events.h>

	#include "xen-ops.h"
	#include "mmu.h"

	cpumask_t xen_cpu_initialized_map;
	static DEFINE_PER_CPU(int, resched_irq) = -1;
	static DEFINE_PER_CPU(int, callfunc_irq) = -1;
	static DEFINE_PER_CPU(int, debug_irq) = -1;

	/*
	* Structure and data for smp_call_function(). This is designed to minimise
	* static memory requirements. It also looks cleaner.
	*/
	static DEFINE_SPINLOCK(call_lock);

	struct call_data_struct {
	void (func) (void info);
	void *info;
	atomic_t started;
	atomic_t finished;
	int wait;
	};

	static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id);

	static struct call_data_struct *call_data;

	/*
	* Reschedule call back. Nothing to do,
	* all the work is done automatically when
	* we return from the interrupt.
	*/
	static irqreturn_t xen_reschedule_interrupt(int irq, void *dev_id)
	{
	#ifdef CONFIG_X86_32
	__get_cpu_var(irq_stat).irq_resched_count++;
	#else
	add_pda(irq_resched_count, 1);
	#endif

	return IRQ_HANDLED;
	}

	static __cpuinit void cpu_bringup_and_idle(void)
	{
	int cpu = smp_processor_id();

	cpu_init();
	xen_enable_sysenter();

	preempt_disable();
	per_cpu(cpu_state, cpu) = CPU_ONLINE;

	xen_setup_cpu_clockevents();

	/* We can take interrupts now: we're officially "up". */
	local_irq_enable();

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

	static int xen_smp_intr_init(unsigned int cpu)
	{
	int rc;
	const char resched_name, callfunc_name, *debug_name;

	resched_name = kasprintf(GFP_KERNEL, "resched%d", cpu);
	rc = bind_ipi_to_irqhandler(XEN_RESCHEDULE_VECTOR,
	cpu,
	xen_reschedule_interrupt,
	IRQF_DISABLED\|IRQF_PERCPU\|IRQF_NOBALANCING,
	resched_name,
	NULL);
	if (rc < 0)
	goto fail;
	per_cpu(resched_irq, cpu) = rc;

	callfunc_name = kasprintf(GFP_KERNEL, "callfunc%d", cpu);
	rc = bind_ipi_to_irqhandler(XEN_CALL_FUNCTION_VECTOR,
	cpu,
	xen_call_function_interrupt,
	IRQF_DISABLED\|IRQF_PERCPU\|IRQF_NOBALANCING,
	callfunc_name,
	NULL);
	if (rc < 0)
	goto fail;
	per_cpu(callfunc_irq, cpu) = rc;

	debug_name = kasprintf(GFP_KERNEL, "debug%d", cpu);
	rc = bind_virq_to_irqhandler(VIRQ_DEBUG, cpu, xen_debug_interrupt,
	IRQF_DISABLED \| IRQF_PERCPU \| IRQF_NOBALANCING,
	debug_name, NULL);
	if (rc < 0)
	goto fail;
	per_cpu(debug_irq, cpu) = rc;

	return 0;

	fail:
	if (per_cpu(resched_irq, cpu) >= 0)
	unbind_from_irqhandler(per_cpu(resched_irq, cpu), NULL);
	if (per_cpu(callfunc_irq, cpu) >= 0)
	unbind_from_irqhandler(per_cpu(callfunc_irq, cpu), NULL);
	if (per_cpu(debug_irq, cpu) >= 0)
	unbind_from_irqhandler(per_cpu(debug_irq, cpu), NULL);
	return rc;
	}

	void __init xen_fill_possible_map(void)
	{
	int i, rc;

	for (i = 0; i < NR_CPUS; i++) {
	rc = HYPERVISOR_vcpu_op(VCPUOP_is_up, i, NULL);
	if (rc >= 0)
	cpu_set(i, cpu_possible_map);
	}
	}

	void __init xen_smp_prepare_boot_cpu(void)
	{
	int cpu;

	BUG_ON(smp_processor_id() != 0);
	native_smp_prepare_boot_cpu();

	/* We've switched to the "real" per-cpu gdt, so make sure the
	old memory can be recycled */
	make_lowmem_page_readwrite(&per_cpu__gdt_page);

	for_each_possible_cpu(cpu) {
	cpus_clear(per_cpu(cpu_sibling_map, cpu));
	/*
	* cpu_core_map lives in a per cpu area that is cleared
	* when the per cpu array is allocated.
	*
	* cpus_clear(per_cpu(cpu_core_map, cpu));
	*/
	}

	xen_setup_vcpu_info_placement();
	}

	void __init xen_smp_prepare_cpus(unsigned int max_cpus)
	{
	unsigned cpu;

	for_each_possible_cpu(cpu) {
	cpus_clear(per_cpu(cpu_sibling_map, cpu));
	/*
	* cpu_core_ map will be zeroed when the per
	* cpu area is allocated.
	*
	* cpus_clear(per_cpu(cpu_core_map, cpu));
	*/
	}

	smp_store_cpu_info(0);
	set_cpu_sibling_map(0);

	if (xen_smp_intr_init(0))
	BUG();

	xen_cpu_initialized_map = cpumask_of_cpu(0);

	/* Restrict the possible_map according to max_cpus. */
	while ((num_possible_cpus() > 1) && (num_possible_cpus() > max_cpus)) {
	for (cpu = NR_CPUS - 1; !cpu_possible(cpu); cpu--)
	continue;
	cpu_clear(cpu, cpu_possible_map);
	}

	for_each_possible_cpu (cpu) {
	struct task_struct *idle;

	if (cpu == 0)
	continue;

	idle = fork_idle(cpu);
	if (IS_ERR(idle))
	panic("failed fork for CPU %d", cpu);

	cpu_set(cpu, cpu_present_map);
	}

	//init_xenbus_allowed_cpumask();
	}

	static __cpuinit int
	cpu_initialize_context(unsigned int cpu, struct task_struct *idle)
	{
	struct vcpu_guest_context *ctxt;
	struct gdt_page *gdt = &per_cpu(gdt_page, cpu);

	if (cpu_test_and_set(cpu, xen_cpu_initialized_map))
	return 0;

	ctxt = kzalloc(sizeof(*ctxt), GFP_KERNEL);
	if (ctxt == NULL)
	return -ENOMEM;

	ctxt->flags = VGCF_IN_KERNEL;
	ctxt->user_regs.ds = __USER_DS;
	ctxt->user_regs.es = __USER_DS;
	ctxt->user_regs.fs = __KERNEL_PERCPU;
	ctxt->user_regs.gs = 0;
	ctxt->user_regs.ss = __KERNEL_DS;
	ctxt->user_regs.eip = (unsigned long)cpu_bringup_and_idle;
	ctxt->user_regs.eflags = 0x1000; /* IOPL_RING1 */

	memset(&ctxt->fpu_ctxt, 0, sizeof(ctxt->fpu_ctxt));

	xen_copy_trap_info(ctxt->trap_ctxt);

	ctxt->ldt_ents = 0;

	BUG_ON((unsigned long)gdt->gdt & ~PAGE_MASK);
	make_lowmem_page_readonly(gdt->gdt);

	ctxt->gdt_frames[0] = virt_to_mfn(gdt->gdt);
	ctxt->gdt_ents = ARRAY_SIZE(gdt->gdt);

	ctxt->user_regs.cs = __KERNEL_CS;
	ctxt->user_regs.esp = idle->thread.sp0 - sizeof(struct pt_regs);

	ctxt->kernel_ss = __KERNEL_DS;
	ctxt->kernel_sp = idle->thread.sp0;

	ctxt->event_callback_cs = __KERNEL_CS;
	ctxt->event_callback_eip = (unsigned long)xen_hypervisor_callback;
	ctxt->failsafe_callback_cs = __KERNEL_CS;
	ctxt->failsafe_callback_eip = (unsigned long)xen_failsafe_callback;

	per_cpu(xen_cr3, cpu) = __pa(swapper_pg_dir);
	ctxt->ctrlreg[3] = xen_pfn_to_cr3(virt_to_mfn(swapper_pg_dir));

	if (HYPERVISOR_vcpu_op(VCPUOP_initialise, cpu, ctxt))
	BUG();

	kfree(ctxt);
	return 0;
	}

	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

	init_gdt(cpu);
	per_cpu(current_task, cpu) = idle;
	irq_ctx_init(cpu);
	xen_setup_timer(cpu);

	/* make sure interrupts start blocked */
	per_cpu(xen_vcpu, cpu)->evtchn_upcall_mask = 1;

	rc = cpu_initialize_context(cpu, idle);
	if (rc)
	return rc;

	if (num_online_cpus() == 1)
	alternatives_smp_switch(1);

	rc = xen_smp_intr_init(cpu);
	if (rc)
	return rc;

	smp_store_cpu_info(cpu);
	set_cpu_sibling_map(cpu);
	/* This must be done before setting cpu_online_map */
	wmb();

	cpu_set(cpu, cpu_online_map);

	rc = HYPERVISOR_vcpu_op(VCPUOP_up, cpu, NULL);
	BUG_ON(rc);

	return 0;
	}

	void xen_smp_cpus_done(unsigned int max_cpus)
	{
	}

	static void stop_self(void *v)
	{
	int cpu = smp_processor_id();

	/* make sure we're not pinning something down */
	load_cr3(swapper_pg_dir);
	/* should set up a minimal gdt */

	HYPERVISOR_vcpu_op(VCPUOP_down, cpu, NULL);
	BUG();
	}

	void xen_smp_send_stop(void)
	{
	smp_call_function(stop_self, NULL, 0, 0);
	}

	void xen_smp_send_reschedule(int cpu)
	{
	xen_send_IPI_one(cpu, XEN_RESCHEDULE_VECTOR);
	}


	static void xen_send_IPI_mask(cpumask_t mask, enum ipi_vector vector)
	{
	unsigned cpu;

	cpus_and(mask, mask, cpu_online_map);

	for_each_cpu_mask(cpu, mask)
	xen_send_IPI_one(cpu, vector);
	}

	static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id)
	{
	void (func) (void info) = call_data->func;
	void *info = call_data->info;
	int wait = call_data->wait;

	/*
	* Notify initiating CPU that I've grabbed the data and am
	* about to execute the function
	*/
	mb();
	atomic_inc(&call_data->started);
	/*
	* At this point the info structure may be out of scope unless wait==1
	*/
	irq_enter();
	(*func)(info);
	__get_cpu_var(irq_stat).irq_call_count++;
	irq_exit();

	if (wait) {
	mb(); /* commit everything before setting finished */
	atomic_inc(&call_data->finished);
	}

	return IRQ_HANDLED;
	}

	int xen_smp_call_function_mask(cpumask_t mask, void (func)(void ),
	void *info, int wait)
	{
	struct call_data_struct data;
	int cpus, cpu;
	bool yield;

	/* Holding any lock stops cpus from going down. */
	spin_lock(&call_lock);

	cpu_clear(smp_processor_id(), mask);

	cpus = cpus_weight(mask);
	if (!cpus) {
	spin_unlock(&call_lock);
	return 0;
	}

	/* Can deadlock when called with interrupts disabled */
	WARN_ON(irqs_disabled());

	data.func = func;
	data.info = info;
	atomic_set(&data.started, 0);
	data.wait = wait;
	if (wait)
	atomic_set(&data.finished, 0);

	call_data = &data;
	mb(); /* write everything before IPI */

	/* Send a message to other CPUs and wait for them to respond */
	xen_send_IPI_mask(mask, XEN_CALL_FUNCTION_VECTOR);

	/* Make sure other vcpus get a chance to run if they need to. */
	yield = false;
	for_each_cpu_mask(cpu, mask)
	if (xen_vcpu_stolen(cpu))
	yield = true;

	if (yield)
	HYPERVISOR_sched_op(SCHEDOP_yield, 0);

	/* Wait for response */
	while (atomic_read(&data.started) != cpus \|\|
	(wait && atomic_read(&data.finished) != cpus))
	cpu_relax();

	spin_unlock(&call_lock);

	return 0;
	}