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         unsigned int i;
 209
 210         xen_init_lock_cpu(0);
 211
 212         smp_store_cpu_info(0);
 213         cpu_data(0).x86_max_cores = 1;
 214
 215         for_each_possible_cpu(i) {
 216                 zalloc_cpumask_var(&per_cpu(cpu_sibling_map, i), GFP_KERNEL);
 217                 zalloc_cpumask_var(&per_cpu(cpu_core_map, i), GFP_KERNEL);
 218                 zalloc_cpumask_var(&per_cpu(cpu_llc_shared_map, i), GFP_KERNEL);
 219         }
 220         set_cpu_sibling_map(0);
 221
 222         if (xen_smp_intr_init(0))
 223                 BUG();
 224
 225         if (!alloc_cpumask_var(&xen_cpu_initialized_map, GFP_KERNEL))
 226                 panic("could not allocate xen_cpu_initialized_map\n");
 227
 228         cpumask_copy(xen_cpu_initialized_map, cpumask_of(0));
 229
 230         /* Restrict the possible_map according to max_cpus. */
 231         while ((num_possible_cpus() > 1) && (num_possible_cpus() > max_cpus)) {
 232                 for (cpu = nr_cpu_ids - 1; !cpu_possible(cpu); cpu--)
 233                         continue;
 234                 set_cpu_possible(cpu, false);
 235         }
 236
 237         for_each_possible_cpu (cpu) {
 238                 struct task_struct *idle;
 239
 240                 if (cpu == 0)
 241                         continue;
 242
 243                 idle = fork_idle(cpu);
 244                 if (IS_ERR(idle))
 245                         panic("failed fork for CPU %d", cpu);
 246
 247                 set_cpu_present(cpu, true);
 248         }
 249 }
 250
 251 static int __cpuinit
 252 cpu_initialize_context(unsigned int cpu, struct task_struct *idle)
 253 {
 254         struct vcpu_guest_context *ctxt;
 255         struct desc_struct *gdt;
 256         unsigned long gdt_mfn;
 257
 258         if (cpumask_test_and_set_cpu(cpu, xen_cpu_initialized_map))
 259                 return 0;
 260
 261         ctxt = kzalloc(sizeof(*ctxt), GFP_KERNEL);
 262         if (ctxt == NULL)
 263                 return -ENOMEM;
 264
 265         gdt = get_cpu_gdt_table(cpu);
 266
 267         ctxt->flags = VGCF_IN_KERNEL;
 268         ctxt->user_regs.ds = __USER_DS;
 269         ctxt->user_regs.es = __USER_DS;
 270         ctxt->user_regs.ss = __KERNEL_DS;
 271 #ifdef CONFIG_X86_32
 272         ctxt->user_regs.fs = __KERNEL_PERCPU;
 273         ctxt->user_regs.gs = __KERNEL_STACK_CANARY;
 274 #else
 275         ctxt->gs_base_kernel = per_cpu_offset(cpu);
 276 #endif
 277         ctxt->user_regs.eip = (unsigned long)cpu_bringup_and_idle;
 278         ctxt->user_regs.eflags = 0x1000; /* IOPL_RING1 */
 279
 280         memset(&ctxt->fpu_ctxt, 0, sizeof(ctxt->fpu_ctxt));
 281
 282         xen_copy_trap_info(ctxt->trap_ctxt);
 283
 284         ctxt->ldt_ents = 0;
 285
 286         BUG_ON((unsigned long)gdt & ~PAGE_MASK);
 287
 288         gdt_mfn = arbitrary_virt_to_mfn(gdt);
 289         make_lowmem_page_readonly(gdt);
 290         make_lowmem_page_readonly(mfn_to_virt(gdt_mfn));
 291
 292         ctxt->gdt_frames[0] = gdt_mfn;
 293         ctxt->gdt_ents      = GDT_ENTRIES;
 294
 295         ctxt->user_regs.cs = __KERNEL_CS;
 296         ctxt->user_regs.esp = idle->thread.sp0 - sizeof(struct pt_regs);
 297
 298         ctxt->kernel_ss = __KERNEL_DS;
 299         ctxt->kernel_sp = idle->thread.sp0;
 300
 301 #ifdef CONFIG_X86_32
 302         ctxt->event_callback_cs     = __KERNEL_CS;
 303         ctxt->failsafe_callback_cs  = __KERNEL_CS;
 304 #endif
 305         ctxt->event_callback_eip    = (unsigned long)xen_hypervisor_callback;
 306         ctxt->failsafe_callback_eip = (unsigned long)xen_failsafe_callback;
 307
 308         per_cpu(xen_cr3, cpu) = __pa(swapper_pg_dir);
 309         ctxt->ctrlreg[3] = xen_pfn_to_cr3(virt_to_mfn(swapper_pg_dir));
 310
 311         if (HYPERVISOR_vcpu_op(VCPUOP_initialise, cpu, ctxt))
 312                 BUG();
 313
 314         kfree(ctxt);
 315         return 0;
 316 }
 317
 318 static int __cpuinit xen_cpu_up(unsigned int cpu)
 319 {
 320         struct task_struct *idle = idle_task(cpu);
 321         int rc;
 322
 323         per_cpu(current_task, cpu) = idle;
 324 #ifdef CONFIG_X86_32
 325         irq_ctx_init(cpu);
 326 #else
 327         clear_tsk_thread_flag(idle, TIF_FORK);
 328         per_cpu(kernel_stack, cpu) =
 329                 (unsigned long)task_stack_page(idle) -
 330                 KERNEL_STACK_OFFSET + THREAD_SIZE;
 331 #endif
 332         xen_setup_runstate_info(cpu);
 333         xen_setup_timer(cpu);
 334         xen_init_lock_cpu(cpu);
 335
 336         per_cpu(cpu_state, cpu) = CPU_UP_PREPARE;
 337
 338         /* make sure interrupts start blocked */
 339         per_cpu(xen_vcpu, cpu)->evtchn_upcall_mask = 1;
 340
 341         rc = cpu_initialize_context(cpu, idle);
 342         if (rc)
 343                 return rc;
 344
 345         if (num_online_cpus() == 1)
 346                 alternatives_smp_switch(1);
 347
 348         rc = xen_smp_intr_init(cpu);
 349         if (rc)
 350                 return rc;
 351
 352         rc = HYPERVISOR_vcpu_op(VCPUOP_up, cpu, NULL);
 353         BUG_ON(rc);
 354
 355         while(per_cpu(cpu_state, cpu) != CPU_ONLINE) {
 356                 HYPERVISOR_sched_op(SCHEDOP_yield, NULL);
 357                 barrier();
 358         }
 359
 360         return 0;
 361 }
 362
 363 static void xen_smp_cpus_done(unsigned int max_cpus)
 364 {
 365 }
 366
 367 #ifdef CONFIG_HOTPLUG_CPU
 368 static int xen_cpu_disable(void)
 369 {
 370         unsigned int cpu = smp_processor_id();
 371         if (cpu == 0)
 372                 return -EBUSY;
 373
 374         cpu_disable_common();
 375
 376         load_cr3(swapper_pg_dir);
 377         return 0;
 378 }
 379
 380 static void xen_cpu_die(unsigned int cpu)
 381 {
 382         while (HYPERVISOR_vcpu_op(VCPUOP_is_up, cpu, NULL)) {
 383                 current->state = TASK_UNINTERRUPTIBLE;
 384                 schedule_timeout(HZ/10);
 385         }
 386         unbind_from_irqhandler(per_cpu(xen_resched_irq, cpu), NULL);
 387         unbind_from_irqhandler(per_cpu(xen_callfunc_irq, cpu), NULL);
 388         unbind_from_irqhandler(per_cpu(xen_debug_irq, cpu), NULL);
 389         unbind_from_irqhandler(per_cpu(xen_callfuncsingle_irq, cpu), NULL);
 390         xen_uninit_lock_cpu(cpu);
 391         xen_teardown_timer(cpu);
 392
 393         if (num_online_cpus() == 1)
 394                 alternatives_smp_switch(0);
 395 }
 396
 397 static void __cpuinit xen_play_dead(void) /* used only with HOTPLUG_CPU */
 398 {
 399         play_dead_common();
 400         HYPERVISOR_vcpu_op(VCPUOP_down, smp_processor_id(), NULL);
 401         cpu_bringup();
 402 }
 403
 404 #else /* !CONFIG_HOTPLUG_CPU */
 405 static int xen_cpu_disable(void)
 406 {
 407         return -ENOSYS;
 408 }
 409
 410 static void xen_cpu_die(unsigned int cpu)
 411 {
 412         BUG();
 413 }
 414
 415 static void xen_play_dead(void)
 416 {
 417         BUG();
 418 }
 419
 420 #endif
 421 static void stop_self(void *v)
 422 {
 423         int cpu = smp_processor_id();
 424
 425         /* make sure we're not pinning something down */
 426         load_cr3(swapper_pg_dir);
 427         /* should set up a minimal gdt */
 428
 429         set_cpu_online(cpu, false);
 430
 431         HYPERVISOR_vcpu_op(VCPUOP_down, cpu, NULL);
 432         BUG();
 433 }
 434
 435 static void xen_stop_other_cpus(int wait)
 436 {
 437         smp_call_function(stop_self, NULL, wait);
 438 }
 439
 440 static void xen_smp_send_reschedule(int cpu)
 441 {
 442         xen_send_IPI_one(cpu, XEN_RESCHEDULE_VECTOR);
 443 }
 444
 445 static void xen_send_IPI_mask(const struct cpumask *mask,
 446                               enum ipi_vector vector)
 447 {
 448         unsigned cpu;
 449
 450         for_each_cpu_and(cpu, mask, cpu_online_mask)
 451                 xen_send_IPI_one(cpu, vector);
 452 }
 453
 454 static void xen_smp_send_call_function_ipi(const struct cpumask *mask)
 455 {
 456         int cpu;
 457
 458         xen_send_IPI_mask(mask, XEN_CALL_FUNCTION_VECTOR);
 459
 460         /* Make sure other vcpus get a chance to run if they need to. */
 461         for_each_cpu(cpu, mask) {
 462                 if (xen_vcpu_stolen(cpu)) {
 463                         HYPERVISOR_sched_op(SCHEDOP_yield, NULL);
 464                         break;
 465                 }
 466         }
 467 }
 468
 469 static void xen_smp_send_call_function_single_ipi(int cpu)
 470 {
 471         xen_send_IPI_mask(cpumask_of(cpu),
 472                           XEN_CALL_FUNCTION_SINGLE_VECTOR);
 473 }
 474
 475 static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id)
 476 {
 477         irq_enter();
 478         generic_smp_call_function_interrupt();
 479         inc_irq_stat(irq_call_count);
 480         irq_exit();
 481
 482         return IRQ_HANDLED;
 483 }
 484
 485 static irqreturn_t xen_call_function_single_interrupt(int irq, void *dev_id)
 486 {
 487         irq_enter();
 488         generic_smp_call_function_single_interrupt();
 489         inc_irq_stat(irq_call_count);
 490         irq_exit();
 491
 492         return IRQ_HANDLED;
 493 }
 494
 495 static const struct smp_ops xen_smp_ops __initconst = {
 496         .smp_prepare_boot_cpu = xen_smp_prepare_boot_cpu,
 497         .smp_prepare_cpus = xen_smp_prepare_cpus,
 498         .smp_cpus_done = xen_smp_cpus_done,
 499
 500         .cpu_up = xen_cpu_up,
 501         .cpu_die = xen_cpu_die,
 502         .cpu_disable = xen_cpu_disable,
 503         .play_dead = xen_play_dead,
 504
 505         .stop_other_cpus = xen_stop_other_cpus,
 506         .smp_send_reschedule = xen_smp_send_reschedule,
 507
 508         .send_call_func_ipi = xen_smp_send_call_function_ipi,
 509         .send_call_func_single_ipi = xen_smp_send_call_function_single_ipi,
 510 };
 511
 512 void __init xen_smp_init(void)
 513 {
 514         smp_ops = xen_smp_ops;
 515         xen_fill_possible_map();
 516         xen_init_spinlocks();
 517 }
 518
 519 static void __init xen_hvm_smp_prepare_cpus(unsigned int max_cpus)
 520 {
 521         native_smp_prepare_cpus(max_cpus);
 522         WARN_ON(xen_smp_intr_init(0));
 523
 524         xen_init_lock_cpu(0);
 525         xen_init_spinlocks();
 526 }
 527
 528 static int __cpuinit xen_hvm_cpu_up(unsigned int cpu)
 529 {
 530         int rc;
 531         rc = native_cpu_up(cpu);
 532         WARN_ON (xen_smp_intr_init(cpu));
 533         return rc;
 534 }
 535
 536 static void xen_hvm_cpu_die(unsigned int cpu)
 537 {
 538         unbind_from_irqhandler(per_cpu(xen_resched_irq, cpu), NULL);
 539         unbind_from_irqhandler(per_cpu(xen_callfunc_irq, cpu), NULL);
 540         unbind_from_irqhandler(per_cpu(xen_debug_irq, cpu), NULL);
 541         unbind_from_irqhandler(per_cpu(xen_callfuncsingle_irq, cpu), NULL);
 542         native_cpu_die(cpu);
 543 }
 544
 545 void __init xen_hvm_smp_init(void)
 546 {
 547         if (!xen_have_vector_callback)
 548                 return;
 549         smp_ops.smp_prepare_cpus = xen_hvm_smp_prepare_cpus;
 550         smp_ops.smp_send_reschedule = xen_smp_send_reschedule;
 551         smp_ops.cpu_up = xen_hvm_cpu_up;
 552         smp_ops.cpu_die = xen_hvm_cpu_die;
 553         smp_ops.send_call_func_ipi = xen_smp_send_call_function_ipi;
 554         smp_ops.send_call_func_single_ipi = xen_smp_send_call_function_single_ipi;
 555 }