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smp.c 8.82 KiB
/*
* 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"
static cpumask_t cpu_initialized_map;
static DEFINE_PER_CPU(int, resched_irq);
static DEFINE_PER_CPU(int, callfunc_irq);
/*
* 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)
{
return IRQ_HANDLED;
}
static __cpuinit void cpu_bringup_and_idle(void){
int cpu = smp_processor_id();
cpu_init();
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;
per_cpu(resched_irq, cpu) = per_cpu(callfunc_irq, cpu) = -1;
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;
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);
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 (cpu = 0; cpu < NR_CPUS; cpu++) {
cpus_clear(cpu_sibling_map[cpu]);
cpus_clear(cpu_core_map[cpu]);
}
xen_setup_vcpu_info_placement();
}
void __init xen_smp_prepare_cpus(unsigned int max_cpus)
{
unsigned cpu;
for (cpu = 0; cpu < NR_CPUS; cpu++) {
cpus_clear(cpu_sibling_map[cpu]);
cpus_clear(cpu_core_map[cpu]);
}
smp_store_cpu_info(0);
set_cpu_sibling_map(0);
if (xen_smp_intr_init(0))
BUG();
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_isset(cpu, cpu_possible_map); 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, 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.esp0 - sizeof(struct pt_regs);
ctxt->kernel_ss = __KERNEL_DS;
ctxt->kernel_sp = idle->thread.esp0;
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);
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;
/* 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.
XXX too severe? Maybe we should check the other CPU's states? */
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;
}