arch/x86/xen/smp.c

   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/slab.h>
  18 #include <linux/smp.h>
  19
  20 #include <asm/paravirt.h>
  21 #include <asm/desc.h>
  22 #include <asm/pgtable.h>
  23 #include <asm/cpu.h>
  24
  25 #include <xen/interface/xen.h>
  26 #include <xen/interface/vcpu.h>
  27
  28 #include <asm/xen/interface.h>
  29 #include <asm/xen/hypercall.h>
  30
  31 #include <xen/xen.h>
  32 #include <xen/page.h>
  33 #include <xen/events.h>
  34
  35 #include <xen/hvc-console.h>
  36 #include "xen-ops.h"
  37 #include "mmu.h"
  38
  39 cpumask_var_t xen_cpu_initialized_map;
  40
  41 static DEFINE_PER_CPU(int, xen_resched_irq);
  42 static DEFINE_PER_CPU(int, xen_callfunc_irq);
  43 static DEFINE_PER_CPU(int, xen_callfuncsingle_irq);
  44 static DEFINE_PER_CPU(int, xen_debug_irq) = -1;
  45
  46 static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id);
  47 static irqreturn_t xen_call_function_single_interrupt(int irq, void *dev_id);
  48
  49 /*
  50  * Reschedule call back.
  51  */
  52 static irqreturn_t xen_reschedule_interrupt(int irq, void *dev_id)
  53 {
  54         inc_irq_stat(irq_resched_count);
  55         scheduler_ipi();
  56
  57         return IRQ_HANDLED;
  58 }
  59
  60 static void __cpuinit cpu_bringup(void)
  61 {
  62         int cpu = smp_processor_id();
  63
  64         cpu_init();
  65         touch_softlockup_watchdog();
  66         preempt_disable();
  67
  68         xen_enable_sysenter();
  69         xen_enable_syscall();
  70
  71         cpu = smp_processor_id();
  72         smp_store_cpu_info(cpu);
  73         cpu_data(cpu).x86_max_cores = 1;
  74         set_cpu_sibling_map(cpu);
  75
  76         xen_setup_cpu_clockevents();
  77
  78         set_cpu_online(cpu, true);
  79         percpu_write(cpu_state, CPU_ONLINE);
  80         wmb();
  81
  82         /* We can take interrupts now: we're officially "up". */
  83         local_irq_enable();
  84
  85         wmb();                  /* make sure everything is out */
  86 }
  87
  88 static void __cpuinit cpu_bringup_and_idle(void)
  89 {
  90         cpu_bringup();
  91         cpu_idle();
  92 }
  93
  94 static int xen_smp_intr_init(unsigned int cpu)
  95 {
  96         int rc;
  97         const char *resched_name, *callfunc_name, *debug_name;
  98
  99         resched_name = kasprintf(GFP_KERNEL, "resched%d", cpu);
 100         rc = bind_ipi_to_irqhandler(XEN_RESCHEDULE_VECTOR,
 101                                     cpu,
 102                                     xen_reschedule_interrupt,
 103                                     IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING,
 104                                     resched_name,
 105                                     NULL);
 106         if (rc < 0)
 107                 goto fail;
 108         per_cpu(xen_resched_irq, cpu) = rc;
 109
 110         callfunc_name = kasprintf(GFP_KERNEL, "callfunc%d", cpu);
 111         rc = bind_ipi_to_irqhandler(XEN_CALL_FUNCTION_VECTOR,
 112                                     cpu,
 113                                     xen_call_function_interrupt,
 114                                     IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING,
 115                                     callfunc_name,
 116                                     NULL);
 117         if (rc < 0)
 118                 goto fail;
 119         per_cpu(xen_callfunc_irq, cpu) = rc;
 120
 121         debug_name = kasprintf(GFP_KERNEL, "debug%d", cpu);
 122         rc = bind_virq_to_irqhandler(VIRQ_DEBUG, cpu, xen_debug_interrupt,
 123                                      IRQF_DISABLED | IRQF_PERCPU | IRQF_NOBALANCING,
 124                                      debug_name, NULL);
 125         if (rc < 0)
 126                 goto fail;
 127         per_cpu(xen_debug_irq, cpu) = rc;
 128
 129         callfunc_name = kasprintf(GFP_KERNEL, "callfuncsingle%d", cpu);
 130         rc = bind_ipi_to_irqhandler(XEN_CALL_FUNCTION_SINGLE_VECTOR,
 131                                     cpu,
 132                                     xen_call_function_single_interrupt,
 133                                     IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING,
 134                                     callfunc_name,
 135                                     NULL);
 136         if (rc < 0)
 137                 goto fail;
 138         per_cpu(xen_callfuncsingle_irq, cpu) = rc;
 139
 140         return 0;
 141
 142  fail:
 143         if (per_cpu(xen_resched_irq, cpu) >= 0)
 144                 unbind_from_irqhandler(per_cpu(xen_resched_irq, cpu), NULL);
 145         if (per_cpu(xen_callfunc_irq, cpu) >= 0)
 146                 unbind_from_irqhandler(per_cpu(xen_callfunc_irq, cpu), NULL);
 147         if (per_cpu(xen_debug_irq, cpu) >= 0)
 148                 unbind_from_irqhandler(per_cpu(xen_debug_irq, cpu), NULL);
 149         if (per_cpu(xen_callfuncsingle_irq, cpu) >= 0)
 150                 unbind_from_irqhandler(per_cpu(xen_callfuncsingle_irq, cpu),
 151                                        NULL);
 152
 153         return rc;
 154 }
 155
 156 static void __init xen_fill_possible_map(void)
 157 {
 158         int i, rc;
 159
 160         if (xen_initial_domain())
 161                 return;
 162
 163         for (i = 0; i < nr_cpu_ids; i++) {
 164                 rc = HYPERVISOR_vcpu_op(VCPUOP_is_up, i, NULL);
 165                 if (rc >= 0) {
 166                         num_processors++;
 167                         set_cpu_possible(i, true);
 168                 }
 169         }
 170 }
 171
 172 static void __init xen_filter_cpu_maps(void)
 173 {
 174         int i, rc;
 175
 176         if (!xen_initial_domain())
 177                 return;
 178
 179         num_processors = 0;
 180         disabled_cpus = 0;
 181         for (i = 0; i < nr_cpu_ids; i++) {
 182                 rc = HYPERVISOR_vcpu_op(VCPUOP_is_up, i, NULL);
 183                 if (rc >= 0) {
 184                         num_processors++;
 185                         set_cpu_possible(i, true);
 186                 } else {
 187                         set_cpu_possible(i, false);
 188                         set_cpu_present(i, false);
 189                 }
 190         }
 191 }
 192
 193 static void __init xen_smp_prepare_boot_cpu(void)
 194 {
 195         BUG_ON(smp_processor_id() != 0);
 196         native_smp_prepare_boot_cpu();
 197
 198         /* We've switched to the "real" per-cpu gdt, so make sure the
 199            old memory can be recycled */
 200         make_lowmem_page_readwrite(xen_initial_gdt);
 201
 202         xen_filter_cpu_maps();
 203         xen_setup_vcpu_info_placement();
 204 }
 205
 206 static void __init xen_smp_prepare_cpus(unsigned int max_cpus)
 207 {
 208         unsigned cpu;
 209         unsigned int i;
 210
 211         if (skip_ioapic_setup) {
 212                 char *m = (max_cpus == 0) ?
 213                         "The nosmp parameter is incompatible with Xen; " \
 214                         "use Xen dom0_max_vcpus=1 parameter" :
 215                         "The noapic parameter is incompatible with Xen";
 216
 217                 xen_raw_printk(m);
 218                 panic(m);
 219         }
 220         xen_init_lock_cpu(0);
 221
 222         smp_store_cpu_info(0);
 223         cpu_data(0).x86_max_cores = 1;
 224
 225         for_each_possible_cpu(i) {
 226                 zalloc_cpumask_var(&per_cpu(cpu_sibling_map, i), GFP_KERNEL);
 227                 zalloc_cpumask_var(&per_cpu(cpu_core_map, i), GFP_KERNEL);
 228                 zalloc_cpumask_var(&per_cpu(cpu_llc_shared_map, i), GFP_KERNEL);
 229         }
 230         set_cpu_sibling_map(0);
 231
 232         if (xen_smp_intr_init(0))
 233                 BUG();
 234
 235         if (!alloc_cpumask_var(&xen_cpu_initialized_map, GFP_KERNEL))
 236                 panic("could not allocate xen_cpu_initialized_map\n");
 237
 238         cpumask_copy(xen_cpu_initialized_map, cpumask_of(0));
 239
 240         /* Restrict the possible_map according to max_cpus. */
 241         while ((num_possible_cpus() > 1) && (num_possible_cpus() > max_cpus)) {
 242                 for (cpu = nr_cpu_ids - 1; !cpu_possible(cpu); cpu--)
 243                         continue;
 244                 set_cpu_possible(cpu, false);
 245         }
 246
 247         for_each_possible_cpu (cpu) {
 248                 struct task_struct *idle;
 249
 250                 if (cpu == 0)
 251                         continue;
 252
 253                 idle = fork_idle(cpu);
 254                 if (IS_ERR(idle))
 255                         panic("failed fork for CPU %d", cpu);
 256
 257                 set_cpu_present(cpu, true);
 258         }
 259 }
 260
 261 static int __cpuinit
 262 cpu_initialize_context(unsigned int cpu, struct task_struct *idle)
 263 {
 264         struct vcpu_guest_context *ctxt;
 265         struct desc_struct *gdt;
 266         unsigned long gdt_mfn;
 267
 268         if (cpumask_test_and_set_cpu(cpu, xen_cpu_initialized_map))
 269                 return 0;
 270
 271         ctxt = kzalloc(sizeof(*ctxt), GFP_KERNEL);
 272         if (ctxt == NULL)
 273                 return -ENOMEM;
 274
 275         gdt = get_cpu_gdt_table(cpu);
 276
 277         ctxt->flags = VGCF_IN_KERNEL;
 278         ctxt->user_regs.ds = __USER_DS;
 279         ctxt->user_regs.es = __USER_DS;
 280         ctxt->user_regs.ss = __KERNEL_DS;
 281 #ifdef CONFIG_X86_32
 282         ctxt->user_regs.fs = __KERNEL_PERCPU;
 283         ctxt->user_regs.gs = __KERNEL_STACK_CANARY;
 284 #else
 285         ctxt->gs_base_kernel = per_cpu_offset(cpu);
 286 #endif
 287         ctxt->user_regs.eip = (unsigned long)cpu_bringup_and_idle;
 288         ctxt->user_regs.eflags = 0x1000; /* IOPL_RING1 */
 289
 290         memset(&ctxt->fpu_ctxt, 0, sizeof(ctxt->fpu_ctxt));
 291
 292         xen_copy_trap_info(ctxt->trap_ctxt);
 293
 294         ctxt->ldt_ents = 0;
 295
 296         BUG_ON((unsigned long)gdt & ~PAGE_MASK);
 297
 298         gdt_mfn = arbitrary_virt_to_mfn(gdt);
 299         make_lowmem_page_readonly(gdt);
 300         make_lowmem_page_readonly(mfn_to_virt(gdt_mfn));
 301
 302         ctxt->gdt_frames[0] = gdt_mfn;
 303         ctxt->gdt_ents      = GDT_ENTRIES;
 304
 305         ctxt->user_regs.cs = __KERNEL_CS;
 306         ctxt->user_regs.esp = idle->thread.sp0 - sizeof(struct pt_regs);
 307
 308         ctxt->kernel_ss = __KERNEL_DS;
 309         ctxt->kernel_sp = idle->thread.sp0;
 310
 311 #ifdef CONFIG_X86_32
 312         ctxt->event_callback_cs     = __KERNEL_CS;
 313         ctxt->failsafe_callback_cs  = __KERNEL_CS;
 314 #endif
 315         ctxt->event_callback_eip    = (unsigned long)xen_hypervisor_callback;
 316         ctxt->failsafe_callback_eip = (unsigned long)xen_failsafe_callback;
 317
 318         per_cpu(xen_cr3, cpu) = __pa(swapper_pg_dir);
 319         ctxt->ctrlreg[3] = xen_pfn_to_cr3(virt_to_mfn(swapper_pg_dir));
 320
 321         if (HYPERVISOR_vcpu_op(VCPUOP_initialise, cpu, ctxt))
 322                 BUG();
 323
 324         kfree(ctxt);
 325         return 0;
 326 }
 327
 328 static int __cpuinit xen_cpu_up(unsigned int cpu)
 329 {
 330         struct task_struct *idle = idle_task(cpu);
 331         int rc;
 332
 333         per_cpu(current_task, cpu) = idle;
 334 #ifdef CONFIG_X86_32
 335         irq_ctx_init(cpu);
 336 #else
 337         clear_tsk_thread_flag(idle, TIF_FORK);
 338         per_cpu(kernel_stack, cpu) =
 339                 (unsigned long)task_stack_page(idle) -
 340                 KERNEL_STACK_OFFSET + THREAD_SIZE;
 341 #endif
 342         xen_setup_runstate_info(cpu);
 343         xen_setup_timer(cpu);
 344         xen_init_lock_cpu(cpu);
 345
 346         per_cpu(cpu_state, cpu) = CPU_UP_PREPARE;
 347
 348         /* make sure interrupts start blocked */
 349         per_cpu(xen_vcpu, cpu)->evtchn_upcall_mask = 1;
 350
 351         rc = cpu_initialize_context(cpu, idle);
 352         if (rc)
 353                 return rc;
 354
 355         if (num_online_cpus() == 1)
 356                 alternatives_smp_switch(1);
 357
 358         rc = xen_smp_intr_init(cpu);
 359         if (rc)
 360                 return rc;
 361
 362         rc = HYPERVISOR_vcpu_op(VCPUOP_up, cpu, NULL);
 363         BUG_ON(rc);
 364
 365         while(per_cpu(cpu_state, cpu) != CPU_ONLINE) {
 366                 HYPERVISOR_sched_op(SCHEDOP_yield, NULL);
 367                 barrier();
 368         }
 369
 370         return 0;
 371 }
 372
 373 static void xen_smp_cpus_done(unsigned int max_cpus)
 374 {
 375 }
 376
 377 #ifdef CONFIG_HOTPLUG_CPU
 378 static int xen_cpu_disable(void)
 379 {
 380         unsigned int cpu = smp_processor_id();
 381         if (cpu == 0)
 382                 return -EBUSY;
 383
 384         cpu_disable_common();
 385
 386         load_cr3(swapper_pg_dir);
 387         return 0;
 388 }
 389
 390 static void xen_cpu_die(unsigned int cpu)
 391 {
 392         while (HYPERVISOR_vcpu_op(VCPUOP_is_up, cpu, NULL)) {
 393                 current->state = TASK_UNINTERRUPTIBLE;
 394                 schedule_timeout(HZ/10);
 395         }
 396         unbind_from_irqhandler(per_cpu(xen_resched_irq, cpu), NULL);
 397         unbind_from_irqhandler(per_cpu(xen_callfunc_irq, cpu), NULL);
 398         unbind_from_irqhandler(per_cpu(xen_debug_irq, cpu), NULL);
 399         unbind_from_irqhandler(per_cpu(xen_callfuncsingle_irq, cpu), NULL);
 400         xen_uninit_lock_cpu(cpu);
 401         xen_teardown_timer(cpu);
 402
 403         if (num_online_cpus() == 1)
 404                 alternatives_smp_switch(0);
 405 }
 406
 407 static void __cpuinit xen_play_dead(void) /* used only with HOTPLUG_CPU */
 408 {
 409         play_dead_common();
 410         HYPERVISOR_vcpu_op(VCPUOP_down, smp_processor_id(), NULL);
 411         cpu_bringup();
 412 }
 413
 414 #else /* !CONFIG_HOTPLUG_CPU */
 415 static int xen_cpu_disable(void)
 416 {
 417         return -ENOSYS;
 418 }
 419
 420 static void xen_cpu_die(unsigned int cpu)
 421 {
 422         BUG();
 423 }
 424
 425 static void xen_play_dead(void)
 426 {
 427         BUG();
 428 }
 429
 430 #endif
 431 static void stop_self(void *v)
 432 {
 433         int cpu = smp_processor_id();
 434
 435         /* make sure we're not pinning something down */
 436         load_cr3(swapper_pg_dir);
 437         /* should set up a minimal gdt */
 438
 439         set_cpu_online(cpu, false);
 440
 441         HYPERVISOR_vcpu_op(VCPUOP_down, cpu, NULL);
 442         BUG();
 443 }
 444
 445 static void xen_stop_other_cpus(int wait)
 446 {
 447         smp_call_function(stop_self, NULL, wait);
 448 }
 449
 450 static void xen_smp_send_reschedule(int cpu)
 451 {
 452         xen_send_IPI_one(cpu, XEN_RESCHEDULE_VECTOR);
 453 }
 454
 455 static void xen_send_IPI_mask(const struct cpumask *mask,
 456                               enum ipi_vector vector)
 457 {
 458         unsigned cpu;
 459
 460         for_each_cpu_and(cpu, mask, cpu_online_mask)
 461                 xen_send_IPI_one(cpu, vector);
 462 }
 463
 464 static void xen_smp_send_call_function_ipi(const struct cpumask *mask)
 465 {
 466         int cpu;
 467
 468         xen_send_IPI_mask(mask, XEN_CALL_FUNCTION_VECTOR);
 469
 470         /* Make sure other vcpus get a chance to run if they need to. */
 471         for_each_cpu(cpu, mask) {
 472                 if (xen_vcpu_stolen(cpu)) {
 473                         HYPERVISOR_sched_op(SCHEDOP_yield, NULL);
 474                         break;
 475                 }
 476         }
 477 }
 478
 479 static void xen_smp_send_call_function_single_ipi(int cpu)
 480 {
 481         xen_send_IPI_mask(cpumask_of(cpu),
 482                           XEN_CALL_FUNCTION_SINGLE_VECTOR);
 483 }
 484
 485 static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id)
 486 {
 487         irq_enter();
 488         generic_smp_call_function_interrupt();
 489         inc_irq_stat(irq_call_count);
 490         irq_exit();
 491
 492         return IRQ_HANDLED;
 493 }
 494
 495 static irqreturn_t xen_call_function_single_interrupt(int irq, void *dev_id)
 496 {
 497         irq_enter();
 498         generic_smp_call_function_single_interrupt();
 499         inc_irq_stat(irq_call_count);
 500         irq_exit();
 501
 502         return IRQ_HANDLED;
 503 }
 504
 505 static const struct smp_ops xen_smp_ops __initconst = {
 506         .smp_prepare_boot_cpu = xen_smp_prepare_boot_cpu,
 507         .smp_prepare_cpus = xen_smp_prepare_cpus,
 508         .smp_cpus_done = xen_smp_cpus_done,
 509
 510         .cpu_up = xen_cpu_up,
 511         .cpu_die = xen_cpu_die,
 512         .cpu_disable = xen_cpu_disable,
 513         .play_dead = xen_play_dead,
 514
 515         .stop_other_cpus = xen_stop_other_cpus,
 516         .smp_send_reschedule = xen_smp_send_reschedule,
 517
 518         .send_call_func_ipi = xen_smp_send_call_function_ipi,
 519         .send_call_func_single_ipi = xen_smp_send_call_function_single_ipi,
 520 };
 521
 522 void __init xen_smp_init(void)
 523 {
 524         smp_ops = xen_smp_ops;
 525         xen_fill_possible_map();
 526         xen_init_spinlocks();
 527 }
 528
 529 static void __init xen_hvm_smp_prepare_cpus(unsigned int max_cpus)
 530 {
 531         native_smp_prepare_cpus(max_cpus);
 532         WARN_ON(xen_smp_intr_init(0));
 533
 534         xen_init_lock_cpu(0);
 535 }
 536
 537 static int __cpuinit xen_hvm_cpu_up(unsigned int cpu)
 538 {
 539         int rc;
 540         rc = native_cpu_up(cpu);
 541         WARN_ON (xen_smp_intr_init(cpu));
 542         return rc;
 543 }
 544
 545 static void xen_hvm_cpu_die(unsigned int cpu)
 546 {
 547         unbind_from_irqhandler(per_cpu(xen_resched_irq, cpu), NULL);
 548         unbind_from_irqhandler(per_cpu(xen_callfunc_irq, cpu), NULL);
 549         unbind_from_irqhandler(per_cpu(xen_debug_irq, cpu), NULL);
 550         unbind_from_irqhandler(per_cpu(xen_callfuncsingle_irq, cpu), NULL);
 551         native_cpu_die(cpu);
 552 }
 553
 554 void __init xen_hvm_smp_init(void)
 555 {
 556         if (!xen_have_vector_callback)
 557                 return;
 558         smp_ops.smp_prepare_cpus = xen_hvm_smp_prepare_cpus;
 559         smp_ops.smp_send_reschedule = xen_smp_send_reschedule;
 560         smp_ops.cpu_up = xen_hvm_cpu_up;
 561         smp_ops.cpu_die = xen_hvm_cpu_die;
 562         smp_ops.send_call_func_ipi = xen_smp_send_call_function_ipi;
 563         smp_ops.send_call_func_single_ipi = xen_smp_send_call_function_single_ipi;
 564 }