linux/arch/x86/xen/smp.c
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   1/*
   2 * Xen SMP support
   3 *
   4 * This file implements the Xen versions of smp_ops.  SMP under Xen is
   5 * very straightforward.  Bringing a CPU up is simply a matter of
   6 * loading its initial context and setting it running.
   7 *
   8 * IPIs are handled through the Xen event mechanism.
   9 *
  10 * Because virtual CPUs can be scheduled onto any real CPU, there's no
  11 * useful topology information for the kernel to make use of.  As a
  12 * result, all CPUs are treated as if they're single-core and
  13 * single-threaded.
  14 */
  15#include <linux/sched.h>
  16#include <linux/err.h>
  17#include <linux/smp.h>
  18
  19#include <asm/paravirt.h>
  20#include <asm/desc.h>
  21#include <asm/pgtable.h>
  22#include <asm/cpu.h>
  23
  24#include <xen/interface/xen.h>
  25#include <xen/interface/vcpu.h>
  26
  27#include <asm/xen/interface.h>
  28#include <asm/xen/hypercall.h>
  29
  30#include <xen/page.h>
  31#include <xen/events.h>
  32
  33#include "xen-ops.h"
  34#include "mmu.h"
  35
  36cpumask_t xen_cpu_initialized_map;
  37
  38static DEFINE_PER_CPU(int, resched_irq);
  39static DEFINE_PER_CPU(int, callfunc_irq);
  40static DEFINE_PER_CPU(int, callfuncsingle_irq);
  41static DEFINE_PER_CPU(int, debug_irq) = -1;
  42
  43static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id);
  44static irqreturn_t xen_call_function_single_interrupt(int irq, void *dev_id);
  45
  46/*
  47 * Reschedule call back. Nothing to do,
  48 * all the work is done automatically when
  49 * we return from the interrupt.
  50 */
  51static irqreturn_t xen_reschedule_interrupt(int irq, void *dev_id)
  52{
  53#ifdef CONFIG_X86_32
  54        __get_cpu_var(irq_stat).irq_resched_count++;
  55#else
  56        add_pda(irq_resched_count, 1);
  57#endif
  58
  59        return IRQ_HANDLED;
  60}
  61
  62static __cpuinit void cpu_bringup(void)
  63{
  64        int cpu = smp_processor_id();
  65
  66        cpu_init();
  67        touch_softlockup_watchdog();
  68        preempt_disable();
  69
  70        xen_enable_sysenter();
  71        xen_enable_syscall();
  72
  73        cpu = smp_processor_id();
  74        smp_store_cpu_info(cpu);
  75        cpu_data(cpu).x86_max_cores = 1;
  76        set_cpu_sibling_map(cpu);
  77
  78        xen_setup_cpu_clockevents();
  79
  80        cpu_set(cpu, cpu_online_map);
  81        x86_write_percpu(cpu_state, CPU_ONLINE);
  82        wmb();
  83
  84        /* We can take interrupts now: we're officially "up". */
  85        local_irq_enable();
  86
  87        wmb();                  /* make sure everything is out */
  88}
  89
  90static __cpuinit void cpu_bringup_and_idle(void)
  91{
  92        cpu_bringup();
  93        cpu_idle();
  94}
  95
  96static int xen_smp_intr_init(unsigned int cpu)
  97{
  98        int rc;
  99        const char *resched_name, *callfunc_name, *debug_name;
 100
 101        resched_name = kasprintf(GFP_KERNEL, "resched%d", cpu);
 102        rc = bind_ipi_to_irqhandler(XEN_RESCHEDULE_VECTOR,
 103                                    cpu,
 104                                    xen_reschedule_interrupt,
 105                                    IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING,
 106                                    resched_name,
 107                                    NULL);
 108        if (rc < 0)
 109                goto fail;
 110        per_cpu(resched_irq, cpu) = rc;
 111
 112        callfunc_name = kasprintf(GFP_KERNEL, "callfunc%d", cpu);
 113        rc = bind_ipi_to_irqhandler(XEN_CALL_FUNCTION_VECTOR,
 114                                    cpu,
 115                                    xen_call_function_interrupt,
 116                                    IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING,
 117                                    callfunc_name,
 118                                    NULL);
 119        if (rc < 0)
 120                goto fail;
 121        per_cpu(callfunc_irq, cpu) = rc;
 122
 123        debug_name = kasprintf(GFP_KERNEL, "debug%d", cpu);
 124        rc = bind_virq_to_irqhandler(VIRQ_DEBUG, cpu, xen_debug_interrupt,
 125                                     IRQF_DISABLED | IRQF_PERCPU | IRQF_NOBALANCING,
 126                                     debug_name, NULL);
 127        if (rc < 0)
 128                goto fail;
 129        per_cpu(debug_irq, cpu) = rc;
 130
 131        callfunc_name = kasprintf(GFP_KERNEL, "callfuncsingle%d", cpu);
 132        rc = bind_ipi_to_irqhandler(XEN_CALL_FUNCTION_SINGLE_VECTOR,
 133                                    cpu,
 134                                    xen_call_function_single_interrupt,
 135                                    IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING,
 136                                    callfunc_name,
 137                                    NULL);
 138        if (rc < 0)
 139                goto fail;
 140        per_cpu(callfuncsingle_irq, cpu) = rc;
 141
 142        return 0;
 143
 144 fail:
 145        if (per_cpu(resched_irq, cpu) >= 0)
 146                unbind_from_irqhandler(per_cpu(resched_irq, cpu), NULL);
 147        if (per_cpu(callfunc_irq, cpu) >= 0)
 148                unbind_from_irqhandler(per_cpu(callfunc_irq, cpu), NULL);
 149        if (per_cpu(debug_irq, cpu) >= 0)
 150                unbind_from_irqhandler(per_cpu(debug_irq, cpu), NULL);
 151        if (per_cpu(callfuncsingle_irq, cpu) >= 0)
 152                unbind_from_irqhandler(per_cpu(callfuncsingle_irq, cpu), NULL);
 153
 154        return rc;
 155}
 156
 157static void __init xen_fill_possible_map(void)
 158{
 159        int i, rc;
 160
 161        for (i = 0; i < NR_CPUS; i++) {
 162                rc = HYPERVISOR_vcpu_op(VCPUOP_is_up, i, NULL);
 163                if (rc >= 0) {
 164                        num_processors++;
 165                        cpu_set(i, cpu_possible_map);
 166                }
 167        }
 168}
 169
 170static void __init xen_smp_prepare_boot_cpu(void)
 171{
 172        BUG_ON(smp_processor_id() != 0);
 173        native_smp_prepare_boot_cpu();
 174
 175        /* We've switched to the "real" per-cpu gdt, so make sure the
 176           old memory can be recycled */
 177        make_lowmem_page_readwrite(&per_cpu_var(gdt_page));
 178
 179        xen_setup_vcpu_info_placement();
 180}
 181
 182static void __init xen_smp_prepare_cpus(unsigned int max_cpus)
 183{
 184        unsigned cpu;
 185
 186        xen_init_lock_cpu(0);
 187
 188        smp_store_cpu_info(0);
 189        cpu_data(0).x86_max_cores = 1;
 190        set_cpu_sibling_map(0);
 191
 192        if (xen_smp_intr_init(0))
 193                BUG();
 194
 195        xen_cpu_initialized_map = cpumask_of_cpu(0);
 196
 197        /* Restrict the possible_map according to max_cpus. */
 198        while ((num_possible_cpus() > 1) && (num_possible_cpus() > max_cpus)) {
 199                for (cpu = NR_CPUS - 1; !cpu_possible(cpu); cpu--)
 200                        continue;
 201                cpu_clear(cpu, cpu_possible_map);
 202        }
 203
 204        for_each_possible_cpu (cpu) {
 205                struct task_struct *idle;
 206
 207                if (cpu == 0)
 208                        continue;
 209
 210                idle = fork_idle(cpu);
 211                if (IS_ERR(idle))
 212                        panic("failed fork for CPU %d", cpu);
 213
 214                cpu_set(cpu, cpu_present_map);
 215        }
 216}
 217
 218static __cpuinit int
 219cpu_initialize_context(unsigned int cpu, struct task_struct *idle)
 220{
 221        struct vcpu_guest_context *ctxt;
 222        struct desc_struct *gdt;
 223
 224        if (cpu_test_and_set(cpu, xen_cpu_initialized_map))
 225                return 0;
 226
 227        ctxt = kzalloc(sizeof(*ctxt), GFP_KERNEL);
 228        if (ctxt == NULL)
 229                return -ENOMEM;
 230
 231        gdt = get_cpu_gdt_table(cpu);
 232
 233        ctxt->flags = VGCF_IN_KERNEL;
 234        ctxt->user_regs.ds = __USER_DS;
 235        ctxt->user_regs.es = __USER_DS;
 236        ctxt->user_regs.ss = __KERNEL_DS;
 237#ifdef CONFIG_X86_32
 238        ctxt->user_regs.fs = __KERNEL_PERCPU;
 239#endif
 240        ctxt->user_regs.eip = (unsigned long)cpu_bringup_and_idle;
 241        ctxt->user_regs.eflags = 0x1000; /* IOPL_RING1 */
 242
 243        memset(&ctxt->fpu_ctxt, 0, sizeof(ctxt->fpu_ctxt));
 244
 245        xen_copy_trap_info(ctxt->trap_ctxt);
 246
 247        ctxt->ldt_ents = 0;
 248
 249        BUG_ON((unsigned long)gdt & ~PAGE_MASK);
 250        make_lowmem_page_readonly(gdt);
 251
 252        ctxt->gdt_frames[0] = virt_to_mfn(gdt);
 253        ctxt->gdt_ents      = GDT_ENTRIES;
 254
 255        ctxt->user_regs.cs = __KERNEL_CS;
 256        ctxt->user_regs.esp = idle->thread.sp0 - sizeof(struct pt_regs);
 257
 258        ctxt->kernel_ss = __KERNEL_DS;
 259        ctxt->kernel_sp = idle->thread.sp0;
 260
 261#ifdef CONFIG_X86_32
 262        ctxt->event_callback_cs     = __KERNEL_CS;
 263        ctxt->failsafe_callback_cs  = __KERNEL_CS;
 264#endif
 265        ctxt->event_callback_eip    = (unsigned long)xen_hypervisor_callback;
 266        ctxt->failsafe_callback_eip = (unsigned long)xen_failsafe_callback;
 267
 268        per_cpu(xen_cr3, cpu) = __pa(swapper_pg_dir);
 269        ctxt->ctrlreg[3] = xen_pfn_to_cr3(virt_to_mfn(swapper_pg_dir));
 270
 271        if (HYPERVISOR_vcpu_op(VCPUOP_initialise, cpu, ctxt))
 272                BUG();
 273
 274        kfree(ctxt);
 275        return 0;
 276}
 277
 278static int __cpuinit xen_cpu_up(unsigned int cpu)
 279{
 280        struct task_struct *idle = idle_task(cpu);
 281        int rc;
 282
 283#ifdef CONFIG_X86_64
 284        /* Allocate node local memory for AP pdas */
 285        WARN_ON(cpu == 0);
 286        if (cpu > 0) {
 287                rc = get_local_pda(cpu);
 288                if (rc)
 289                        return rc;
 290        }
 291#endif
 292
 293#ifdef CONFIG_X86_32
 294        init_gdt(cpu);
 295        per_cpu(current_task, cpu) = idle;
 296        irq_ctx_init(cpu);
 297#else
 298        cpu_pda(cpu)->pcurrent = idle;
 299        clear_tsk_thread_flag(idle, TIF_FORK);
 300#endif
 301        xen_setup_timer(cpu);
 302        xen_init_lock_cpu(cpu);
 303
 304        per_cpu(cpu_state, cpu) = CPU_UP_PREPARE;
 305
 306        /* make sure interrupts start blocked */
 307        per_cpu(xen_vcpu, cpu)->evtchn_upcall_mask = 1;
 308
 309        rc = cpu_initialize_context(cpu, idle);
 310        if (rc)
 311                return rc;
 312
 313        if (num_online_cpus() == 1)
 314                alternatives_smp_switch(1);
 315
 316        rc = xen_smp_intr_init(cpu);
 317        if (rc)
 318                return rc;
 319
 320        rc = HYPERVISOR_vcpu_op(VCPUOP_up, cpu, NULL);
 321        BUG_ON(rc);
 322
 323        while(per_cpu(cpu_state, cpu) != CPU_ONLINE) {
 324                HYPERVISOR_sched_op(SCHEDOP_yield, 0);
 325                barrier();
 326        }
 327
 328        return 0;
 329}
 330
 331static void xen_smp_cpus_done(unsigned int max_cpus)
 332{
 333}
 334
 335#ifdef CONFIG_HOTPLUG_CPU
 336static int xen_cpu_disable(void)
 337{
 338        unsigned int cpu = smp_processor_id();
 339        if (cpu == 0)
 340                return -EBUSY;
 341
 342        cpu_disable_common();
 343
 344        load_cr3(swapper_pg_dir);
 345        return 0;
 346}
 347
 348static void xen_cpu_die(unsigned int cpu)
 349{
 350        while (HYPERVISOR_vcpu_op(VCPUOP_is_up, cpu, NULL)) {
 351                current->state = TASK_UNINTERRUPTIBLE;
 352                schedule_timeout(HZ/10);
 353        }
 354        unbind_from_irqhandler(per_cpu(resched_irq, cpu), NULL);
 355        unbind_from_irqhandler(per_cpu(callfunc_irq, cpu), NULL);
 356        unbind_from_irqhandler(per_cpu(debug_irq, cpu), NULL);
 357        unbind_from_irqhandler(per_cpu(callfuncsingle_irq, cpu), NULL);
 358        xen_uninit_lock_cpu(cpu);
 359        xen_teardown_timer(cpu);
 360
 361        if (num_online_cpus() == 1)
 362                alternatives_smp_switch(0);
 363}
 364
 365static void __cpuinit xen_play_dead(void) /* used only with CPU_HOTPLUG */
 366{
 367        play_dead_common();
 368        HYPERVISOR_vcpu_op(VCPUOP_down, smp_processor_id(), NULL);
 369        cpu_bringup();
 370}
 371
 372#else /* !CONFIG_HOTPLUG_CPU */
 373static int xen_cpu_disable(void)
 374{
 375        return -ENOSYS;
 376}
 377
 378static void xen_cpu_die(unsigned int cpu)
 379{
 380        BUG();
 381}
 382
 383static void xen_play_dead(void)
 384{
 385        BUG();
 386}
 387
 388#endif
 389static void stop_self(void *v)
 390{
 391        int cpu = smp_processor_id();
 392
 393        /* make sure we're not pinning something down */
 394        load_cr3(swapper_pg_dir);
 395        /* should set up a minimal gdt */
 396
 397        HYPERVISOR_vcpu_op(VCPUOP_down, cpu, NULL);
 398        BUG();
 399}
 400
 401static void xen_smp_send_stop(void)
 402{
 403        smp_call_function(stop_self, NULL, 0);
 404}
 405
 406static void xen_smp_send_reschedule(int cpu)
 407{
 408        xen_send_IPI_one(cpu, XEN_RESCHEDULE_VECTOR);
 409}
 410
 411static void xen_send_IPI_mask(cpumask_t mask, enum ipi_vector vector)
 412{
 413        unsigned cpu;
 414
 415        cpus_and(mask, mask, cpu_online_map);
 416
 417        for_each_cpu_mask_nr(cpu, mask)
 418                xen_send_IPI_one(cpu, vector);
 419}
 420
 421static void xen_smp_send_call_function_ipi(cpumask_t mask)
 422{
 423        int cpu;
 424
 425        xen_send_IPI_mask(mask, XEN_CALL_FUNCTION_VECTOR);
 426
 427        /* Make sure other vcpus get a chance to run if they need to. */
 428        for_each_cpu_mask_nr(cpu, mask) {
 429                if (xen_vcpu_stolen(cpu)) {
 430                        HYPERVISOR_sched_op(SCHEDOP_yield, 0);
 431                        break;
 432                }
 433        }
 434}
 435
 436static void xen_smp_send_call_function_single_ipi(int cpu)
 437{
 438        xen_send_IPI_mask(cpumask_of_cpu(cpu), XEN_CALL_FUNCTION_SINGLE_VECTOR);
 439}
 440
 441static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id)
 442{
 443        irq_enter();
 444        generic_smp_call_function_interrupt();
 445#ifdef CONFIG_X86_32
 446        __get_cpu_var(irq_stat).irq_call_count++;
 447#else
 448        add_pda(irq_call_count, 1);
 449#endif
 450        irq_exit();
 451
 452        return IRQ_HANDLED;
 453}
 454
 455static irqreturn_t xen_call_function_single_interrupt(int irq, void *dev_id)
 456{
 457        irq_enter();
 458        generic_smp_call_function_single_interrupt();
 459#ifdef CONFIG_X86_32
 460        __get_cpu_var(irq_stat).irq_call_count++;
 461#else
 462        add_pda(irq_call_count, 1);
 463#endif
 464        irq_exit();
 465
 466        return IRQ_HANDLED;
 467}
 468
 469static const struct smp_ops xen_smp_ops __initdata = {
 470        .smp_prepare_boot_cpu = xen_smp_prepare_boot_cpu,
 471        .smp_prepare_cpus = xen_smp_prepare_cpus,
 472        .smp_cpus_done = xen_smp_cpus_done,
 473
 474        .cpu_up = xen_cpu_up,
 475        .cpu_die = xen_cpu_die,
 476        .cpu_disable = xen_cpu_disable,
 477        .play_dead = xen_play_dead,
 478
 479        .smp_send_stop = xen_smp_send_stop,
 480        .smp_send_reschedule = xen_smp_send_reschedule,
 481
 482        .send_call_func_ipi = xen_smp_send_call_function_ipi,
 483        .send_call_func_single_ipi = xen_smp_send_call_function_single_ipi,
 484};
 485
 486void __init xen_smp_init(void)
 487{
 488        smp_ops = xen_smp_ops;
 489        xen_fill_possible_map();
 490        xen_init_spinlocks();
 491}
 492