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