text: /*
   * 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.
   */
  #include <linux/sched.h>
  #include <linux/err.h>
  #include <linux/slab.h>
  #include <linux/smp.h>
  #include <linux/irq_work.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/xen.h>
  #include <xen/page.h>
  #include <xen/events.h>
  
  #include <xen/hvc-console.h>
  #include "xen-ops.h"
  #include "mmu.h"
  
  cpumask_var_t xen_cpu_initialized_map;
  
  static DEFINE_PER_CPU(int, xen_resched_irq);
  static DEFINE_PER_CPU(int, xen_callfunc_irq);
  static DEFINE_PER_CPU(int, xen_callfuncsingle_irq);
  static DEFINE_PER_CPU(int, xen_irq_work);
  static DEFINE_PER_CPU(int, xen_debug_irq) = -1;
  
  static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id);
  static irqreturn_t xen_call_function_single_interrupt(int irq, void *dev_id);
  static irqreturn_t xen_irq_work_interrupt(int irq, void *dev_id);
  
  /*
   * Reschedule call back.
   */
  static irqreturn_t xen_reschedule_interrupt(int irq, void *dev_id)
  {
  	inc_irq_stat(irq_resched_count);
  	scheduler_ipi();
  
  	return IRQ_HANDLED;
  }
  
  static void __cpuinit cpu_bringup(void)
  {
  	int cpu;
  
  	cpu_init();
  	touch_softlockup_watchdog();
  	preempt_disable();
  
  	xen_enable_sysenter();
  	xen_enable_syscall();
  
  	cpu = smp_processor_id();
  	smp_store_cpu_info(cpu);
  	cpu_data(cpu).x86_max_cores = 1;
  	set_cpu_sibling_map(cpu);
  
  	xen_setup_cpu_clockevents();
  
  	notify_cpu_starting(cpu);
  
  	set_cpu_online(cpu, true);
  
  	this_cpu_write(cpu_state, CPU_ONLINE);
  
  	wmb();
  
  	/* We can take interrupts now: we're officially "up". */
  	local_irq_enable();
  
  	wmb();			/* make sure everything is out */
  }
  
  static void __cpuinit cpu_bringup_and_idle(void)
  {
  	cpu_bringup();
  	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(xen_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(xen_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(xen_debug_irq, cpu) = rc;
  
  	callfunc_name = kasprintf(GFP_KERNEL, "callfuncsingle%d", cpu);
  	rc = bind_ipi_to_irqhandler(XEN_CALL_FUNCTION_SINGLE_VECTOR,
  				    cpu,
  				    xen_call_function_single_interrupt,
  				    IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING,
  				    callfunc_name,
  				    NULL);
  	if (rc < 0)
  		goto fail;
  	per_cpu(xen_callfuncsingle_irq, cpu) = rc;
  
  	callfunc_name = kasprintf(GFP_KERNEL, "irqwork%d", cpu);
  	rc = bind_ipi_to_irqhandler(XEN_IRQ_WORK_VECTOR,
  				    cpu,
  				    xen_irq_work_interrupt,
  				    IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING,
  				    callfunc_name,
  				    NULL);
  	if (rc < 0)
  		goto fail;
  	per_cpu(xen_irq_work, cpu) = rc;
  
  	return 0;
  
   fail:
  	if (per_cpu(xen_resched_irq, cpu) >= 0)
  		unbind_from_irqhandler(per_cpu(xen_resched_irq, cpu), NULL);
  	if (per_cpu(xen_callfunc_irq, cpu) >= 0)
  		unbind_from_irqhandler(per_cpu(xen_callfunc_irq, cpu), NULL);
  	if (per_cpu(xen_debug_irq, cpu) >= 0)
  		unbind_from_irqhandler(per_cpu(xen_debug_irq, cpu), NULL);
  	if (per_cpu(xen_callfuncsingle_irq, cpu) >= 0)
  		unbind_from_irqhandler(per_cpu(xen_callfuncsingle_irq, cpu),
  				       NULL);
  	if (per_cpu(xen_irq_work, cpu) >= 0)
  		unbind_from_irqhandler(per_cpu(xen_irq_work, cpu), NULL);
  
  	return rc;
  }
  
  static void __init xen_fill_possible_map(void)
  {
  	int i, rc;
  
  	if (xen_initial_domain())
  		return;
  
  	for (i = 0; i < nr_cpu_ids; i++) {
  		rc = HYPERVISOR_vcpu_op(VCPUOP_is_up, i, NULL);
  		if (rc >= 0) {
  			num_processors++;
  			set_cpu_possible(i, true);
  		}
  	}
  }
  
  static void __init xen_filter_cpu_maps(void)
  {
  	int i, rc;
  	unsigned int subtract = 0;
  
  	if (!xen_initial_domain())
  		return;
  
  	num_processors = 0;
  	disabled_cpus = 0;
  	for (i = 0; i < nr_cpu_ids; i++) {
  		rc = HYPERVISOR_vcpu_op(VCPUOP_is_up, i, NULL);
  		if (rc >= 0) {
  			num_processors++;
  			set_cpu_possible(i, true);
  		} else {
  			set_cpu_possible(i, false);
  			set_cpu_present(i, false);
  			subtract++;
  		}
  	}
  #ifdef CONFIG_HOTPLUG_CPU
  	/* This is akin to using 'nr_cpus' on the Linux command line.
  	 * Which is OK as when we use 'dom0_max_vcpus=X' we can only
  	 * have up to X, while nr_cpu_ids is greater than X. This
  	 * normally is not a problem, except when CPU hotplugging
  	 * is involved and then there might be more than X CPUs
  	 * in the guest - which will not work as there is no
  	 * hypercall to expand the max number of VCPUs an already
  	 * running guest has. So cap it up to X. */
  	if (subtract)
  		nr_cpu_ids = nr_cpu_ids - subtract;
  #endif
  
  }
  
  static void __init xen_smp_prepare_boot_cpu(void)
  {
  	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(xen_initial_gdt);
  
  	xen_filter_cpu_maps();
  	xen_setup_vcpu_info_placement();
  }
  
  static void __init xen_smp_prepare_cpus(unsigned int max_cpus)
  {
  	unsigned cpu;
  	unsigned int i;
  
  	if (skip_ioapic_setup) {
  		char *m = (max_cpus == 0) ?
  			"The nosmp parameter is incompatible with Xen; " \
  			"use Xen dom0_max_vcpus=1 parameter" :
  			"The noapic parameter is incompatible with Xen";
  
  		xen_raw_printk(m);
  		panic(m);
  	}
  	xen_init_lock_cpu(0);
  
  	smp_store_cpu_info(0);
  	cpu_data(0).x86_max_cores = 1;
  
  	for_each_possible_cpu(i) {
  		zalloc_cpumask_var(&per_cpu(cpu_sibling_map, i), GFP_KERNEL);
  		zalloc_cpumask_var(&per_cpu(cpu_core_map, i), GFP_KERNEL);
  		zalloc_cpumask_var(&per_cpu(cpu_llc_shared_map, i), GFP_KERNEL);
  	}
  	set_cpu_sibling_map(0);
  
  	if (xen_smp_intr_init(0))
  		BUG();
  
  	if (!alloc_cpumask_var(&xen_cpu_initialized_map, GFP_KERNEL))
  		panic("could not allocate xen_cpu_initialized_map\n");
  
  	cpumask_copy(xen_cpu_initialized_map, cpumask_of(0));
  
  	/* Restrict the possible_map according to max_cpus. */
  	while ((num_possible_cpus() > 1) && (num_possible_cpus() > max_cpus)) {
  		for (cpu = nr_cpu_ids - 1; !cpu_possible(cpu); cpu--)
  			continue;
  		set_cpu_possible(cpu, false);
  	}
  
  	for_each_possible_cpu(cpu)
  		set_cpu_present(cpu, true);
  }
  
  static int __cpuinit
  cpu_initialize_context(unsigned int cpu, struct task_struct *idle)
  {
  	struct vcpu_guest_context *ctxt;
  	struct desc_struct *gdt;
  	unsigned long gdt_mfn;
  
  	if (cpumask_test_and_set_cpu(cpu, xen_cpu_initialized_map))
  		return 0;
  
  	ctxt = kzalloc(sizeof(*ctxt), GFP_KERNEL);
  	if (ctxt == NULL)
  		return -ENOMEM;
  
  	gdt = get_cpu_gdt_table(cpu);
  
  	ctxt->flags = VGCF_IN_KERNEL;
  	ctxt->user_regs.ds = __USER_DS;
  	ctxt->user_regs.es = __USER_DS;
  	ctxt->user_regs.ss = __KERNEL_DS;
  #ifdef CONFIG_X86_32
  	ctxt->user_regs.fs = __KERNEL_PERCPU;
  	ctxt->user_regs.gs = __KERNEL_STACK_CANARY;
  #else
  	ctxt->gs_base_kernel = per_cpu_offset(cpu);
  #endif
  	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 & ~PAGE_MASK);
  
  	gdt_mfn = arbitrary_virt_to_mfn(gdt);
  	make_lowmem_page_readonly(gdt);
  	make_lowmem_page_readonly(mfn_to_virt(gdt_mfn));
  
  	ctxt->gdt_frames[0] = gdt_mfn;
  	ctxt->gdt_ents      = GDT_ENTRIES;
  
  	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;
  
  #ifdef CONFIG_X86_32
  	ctxt->event_callback_cs     = __KERNEL_CS;
  	ctxt->failsafe_callback_cs  = __KERNEL_CS;
  #endif
  	ctxt->event_callback_eip    = (unsigned long)xen_hypervisor_callback;
  	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;
  }
  
  static int __cpuinit xen_cpu_up(unsigned int cpu, struct task_struct *idle)
  {
  	int rc;
  
  	per_cpu(current_task, cpu) = idle;
  #ifdef CONFIG_X86_32
  	irq_ctx_init(cpu);
  #else
  	clear_tsk_thread_flag(idle, TIF_FORK);
  	per_cpu(kernel_stack, cpu) =
  		(unsigned long)task_stack_page(idle) -
  		KERNEL_STACK_OFFSET + THREAD_SIZE;
  #endif
  	xen_setup_runstate_info(cpu);
  	xen_setup_timer(cpu);
  	xen_init_lock_cpu(cpu);
  
  	per_cpu(cpu_state, cpu) = CPU_UP_PREPARE;
  
  	/* 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)
  		/* Just in case we booted with a single CPU. */
  		alternatives_enable_smp();
  
  	rc = xen_smp_intr_init(cpu);
  	if (rc)
  		return rc;
  
  	rc = HYPERVISOR_vcpu_op(VCPUOP_up, cpu, NULL);
  	BUG_ON(rc);
  
  	while(per_cpu(cpu_state, cpu) != CPU_ONLINE) {
  		HYPERVISOR_sched_op(SCHEDOP_yield, NULL);
  		barrier();
  	}
  
  	return 0;
  }
  
  static void xen_smp_cpus_done(unsigned int max_cpus)
  {
  }
  
  #ifdef CONFIG_HOTPLUG_CPU
  static 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;
  }
  
  static 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(xen_resched_irq, cpu), NULL);
  	unbind_from_irqhandler(per_cpu(xen_callfunc_irq, cpu), NULL);
  	unbind_from_irqhandler(per_cpu(xen_debug_irq, cpu), NULL);
  	unbind_from_irqhandler(per_cpu(xen_callfuncsingle_irq, cpu), NULL);
  	unbind_from_irqhandler(per_cpu(xen_irq_work, cpu), NULL);
  	xen_uninit_lock_cpu(cpu);
  	xen_teardown_timer(cpu);
  }
  
  static void __cpuinit xen_play_dead(void) /* used only with HOTPLUG_CPU */
  {
  	play_dead_common();
  	HYPERVISOR_vcpu_op(VCPUOP_down, smp_processor_id(), NULL);
  	cpu_bringup();
  	/*
  	 * Balance out the preempt calls - as we are running in cpu_idle
  	 * loop which has been called at bootup from cpu_bringup_and_idle.
  	 * The cpucpu_bringup_and_idle called cpu_bringup which made a
  	 * preempt_disable() So this preempt_enable will balance it out.
  	 */
  	preempt_enable();
  }
  
  #else /* !CONFIG_HOTPLUG_CPU */
  static int xen_cpu_disable(void)
  {
  	return -ENOSYS;
  }
  
  static void xen_cpu_die(unsigned int cpu)
  {
  	BUG();
  }
  
  static void xen_play_dead(void)
  {
  	BUG();
  }
  
  #endif
  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 */
  
  	set_cpu_online(cpu, false);
  
  	HYPERVISOR_vcpu_op(VCPUOP_down, cpu, NULL);
  	BUG();
  }
  
  static void xen_stop_other_cpus(int wait)
  {
  	smp_call_function(stop_self, NULL, wait);
  }
  
  static void xen_smp_send_reschedule(int cpu)
  {
  	xen_send_IPI_one(cpu, XEN_RESCHEDULE_VECTOR);
  }
  
  static void __xen_send_IPI_mask(const struct cpumask *mask,
  			      int vector)
  {
  	unsigned cpu;
  
  	for_each_cpu_and(cpu, mask, cpu_online_mask)
  		xen_send_IPI_one(cpu, vector);
  }
  
  static void xen_smp_send_call_function_ipi(const struct cpumask *mask)
  {
  	int cpu;
  
  	__xen_send_IPI_mask(mask, XEN_CALL_FUNCTION_VECTOR);
  
  	/* Make sure other vcpus get a chance to run if they need to. */
  	for_each_cpu(cpu, mask) {
  		if (xen_vcpu_stolen(cpu)) {
  			HYPERVISOR_sched_op(SCHEDOP_yield, NULL);
  			break;
  		}
  	}
  }
  
  static void xen_smp_send_call_function_single_ipi(int cpu)
  {
  	__xen_send_IPI_mask(cpumask_of(cpu),
  			  XEN_CALL_FUNCTION_SINGLE_VECTOR);
  }
  
  static inline int xen_map_vector(int vector)
  {
  	int xen_vector;
  
  	switch (vector) {
  	case RESCHEDULE_VECTOR:
  		xen_vector = XEN_RESCHEDULE_VECTOR;
  		break;
  	case CALL_FUNCTION_VECTOR:
  		xen_vector = XEN_CALL_FUNCTION_VECTOR;
  		break;
  	case CALL_FUNCTION_SINGLE_VECTOR:
  		xen_vector = XEN_CALL_FUNCTION_SINGLE_VECTOR;
  		break;
  	case IRQ_WORK_VECTOR:
  		xen_vector = XEN_IRQ_WORK_VECTOR;
  		break;
  	default:
  		xen_vector = -1;
  		printk(KERN_ERR "xen: vector 0x%x is not implemented\n",
  			vector);
  	}
  
  	return xen_vector;
  }
  
  void xen_send_IPI_mask(const struct cpumask *mask,
  			      int vector)
  {
  	int xen_vector = xen_map_vector(vector);
  
  	if (xen_vector >= 0)
  		__xen_send_IPI_mask(mask, xen_vector);
  }
  
  void xen_send_IPI_all(int vector)
  {
  	int xen_vector = xen_map_vector(vector);
  
  	if (xen_vector >= 0)
  		__xen_send_IPI_mask(cpu_online_mask, xen_vector);
  }
  
  void xen_send_IPI_self(int vector)
  {
  	int xen_vector = xen_map_vector(vector);
  
  	if (xen_vector >= 0)
  		xen_send_IPI_one(smp_processor_id(), xen_vector);
  }
  
  void xen_send_IPI_mask_allbutself(const struct cpumask *mask,
  				int vector)
  {
  	unsigned cpu;
  	unsigned int this_cpu = smp_processor_id();
  
  	if (!(num_online_cpus() > 1))
  		return;
  
  	for_each_cpu_and(cpu, mask, cpu_online_mask) {
  		if (this_cpu == cpu)
  			continue;
  
  		xen_smp_send_call_function_single_ipi(cpu);
  	}
  }
  
  void xen_send_IPI_allbutself(int vector)
  {
  	int xen_vector = xen_map_vector(vector);
  
  	if (xen_vector >= 0)
  		xen_send_IPI_mask_allbutself(cpu_online_mask, xen_vector);
  }
  
  static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id)
  {
  	irq_enter();
  	generic_smp_call_function_interrupt();
  	inc_irq_stat(irq_call_count);
  	irq_exit();
  
  	return IRQ_HANDLED;
  }
  
  static irqreturn_t xen_call_function_single_interrupt(int irq, void *dev_id)
  {
  	irq_enter();
  	generic_smp_call_function_single_interrupt();
  	inc_irq_stat(irq_call_count);
  	irq_exit();
  
  	return IRQ_HANDLED;
  }
  
  static irqreturn_t xen_irq_work_interrupt(int irq, void *dev_id)
  {
  	irq_enter();
  	irq_work_run();
  	inc_irq_stat(apic_irq_work_irqs);
  	irq_exit();
  
  	return IRQ_HANDLED;
  }
  
  static const struct smp_ops xen_smp_ops __initconst = {
  	.smp_prepare_boot_cpu = xen_smp_prepare_boot_cpu,
  	.smp_prepare_cpus = xen_smp_prepare_cpus,
  	.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,
  
  	.stop_other_cpus = xen_stop_other_cpus,
  	.smp_send_reschedule = xen_smp_send_reschedule,
  
  	.send_call_func_ipi = xen_smp_send_call_function_ipi,
  	.send_call_func_single_ipi = xen_smp_send_call_function_single_ipi,
  };
  
  void __init xen_smp_init(void)
  {
  	smp_ops = xen_smp_ops;
  	xen_fill_possible_map();
  	xen_init_spinlocks();
  }
  
  static void __init xen_hvm_smp_prepare_cpus(unsigned int max_cpus)
  {
  	native_smp_prepare_cpus(max_cpus);
  	WARN_ON(xen_smp_intr_init(0));
  
  	xen_init_lock_cpu(0);
  }
  
  static int __cpuinit xen_hvm_cpu_up(unsigned int cpu, struct task_struct *tidle)
  {
  	int rc;
  	rc = native_cpu_up(cpu, tidle);
  	WARN_ON (xen_smp_intr_init(cpu));
  	return rc;
  }
  
  static void xen_hvm_cpu_die(unsigned int cpu)
  {
  	unbind_from_irqhandler(per_cpu(xen_resched_irq, cpu), NULL);
  	unbind_from_irqhandler(per_cpu(xen_callfunc_irq, cpu), NULL);
  	unbind_from_irqhandler(per_cpu(xen_debug_irq, cpu), NULL);
  	unbind_from_irqhandler(per_cpu(xen_callfuncsingle_irq, cpu), NULL);
  	unbind_from_irqhandler(per_cpu(xen_irq_work, cpu), NULL);
  	native_cpu_die(cpu);
  }
  
  void __init xen_hvm_smp_init(void)
  {
  	if (!xen_have_vector_callback)
  		return;
  	smp_ops.smp_prepare_cpus = xen_hvm_smp_prepare_cpus;
  	smp_ops.smp_send_reschedule = xen_smp_send_reschedule;
  	smp_ops.cpu_up = xen_hvm_cpu_up;
  	smp_ops.cpu_die = xen_hvm_cpu_die;
  	smp_ops.send_call_func_ipi = xen_smp_send_call_function_ipi;
  	smp_ops.send_call_func_single_ipi = xen_smp_send_call_function_single_ipi;
  }
  