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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
  36 cpumask_var_t xen_cpu_initialized_map;
  37
  38 static DEFINE_PER_CPU(int, resched_irq);
  39 static DEFINE_PER_CPU(int, callfunc_irq);
  40 static DEFINE_PER_CPU(int, callfuncsingle_irq);
  41 static DEFINE_PER_CPU(int, debug_irq) = -1;
  42
  43 static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id);
  44 static 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  */
  51 static 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
  62 static __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
  90 static __cpuinit void cpu_bringup_and_idle(void)
  91 {
  92         cpu_bringup();
  93         cpu_idle();
  94 }
  95
  96 static 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
 157 static void __init xen_fill_possible_map(void)
 158 {
 159         int i, rc;
 160
 161         for (i = 0; i < nr_cpu_ids; 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
 170 static 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
 182 static 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         if (!alloc_cpumask_var(&xen_cpu_initialized_map, GFP_KERNEL))
 196                 panic("could not allocate xen_cpu_initialized_map\n");
 197
 198         cpumask_copy(xen_cpu_initialized_map, cpumask_of(0));
 199
 200         /* Restrict the possible_map according to max_cpus. */
 201         while ((num_possible_cpus() > 1) && (num_possible_cpus() > max_cpus)) {
 202                 for (cpu = nr_cpu_ids - 1; !cpu_possible(cpu); cpu--)
 203                         continue;
 204                 cpu_clear(cpu, cpu_possible_map);
 205         }
 206
 207         for_each_possible_cpu (cpu) {
 208                 struct task_struct *idle;
 209
 210                 if (cpu == 0)
 211                         continue;
 212
 213                 idle = fork_idle(cpu);
 214                 if (IS_ERR(idle))
 215                         panic("failed fork for CPU %d", cpu);
 216
 217                 cpu_set(cpu, cpu_present_map);
 218         }
 219 }
 220
 221 static __cpuinit int
 222 cpu_initialize_context(unsigned int cpu, struct task_struct *idle)
 223 {
 224         struct vcpu_guest_context *ctxt;
 225         struct desc_struct *gdt;
 226
 227         if (cpumask_test_and_set_cpu(cpu, xen_cpu_initialized_map))
 228                 return 0;
 229
 230         ctxt = kzalloc(sizeof(*ctxt), GFP_KERNEL);
 231         if (ctxt == NULL)
 232                 return -ENOMEM;
 233
 234         gdt = get_cpu_gdt_table(cpu);
 235
 236         ctxt->flags = VGCF_IN_KERNEL;
 237         ctxt->user_regs.ds = __USER_DS;
 238         ctxt->user_regs.es = __USER_DS;
 239         ctxt->user_regs.ss = __KERNEL_DS;
 240 #ifdef CONFIG_X86_32
 241         ctxt->user_regs.fs = __KERNEL_PERCPU;
 242 #endif
 243         ctxt->user_regs.eip = (unsigned long)cpu_bringup_and_idle;
 244         ctxt->user_regs.eflags = 0x1000; /* IOPL_RING1 */
 245
 246         memset(&ctxt->fpu_ctxt, 0, sizeof(ctxt->fpu_ctxt));
 247
 248         xen_copy_trap_info(ctxt->trap_ctxt);
 249
 250         ctxt->ldt_ents = 0;
 251
 252         BUG_ON((unsigned long)gdt & ~PAGE_MASK);
 253         make_lowmem_page_readonly(gdt);
 254
 255         ctxt->gdt_frames[0] = virt_to_mfn(gdt);
 256         ctxt->gdt_ents      = GDT_ENTRIES;
 257
 258         ctxt->user_regs.cs = __KERNEL_CS;
 259         ctxt->user_regs.esp = idle->thread.sp0 - sizeof(struct pt_regs);
 260
 261         ctxt->kernel_ss = __KERNEL_DS;
 262         ctxt->kernel_sp = idle->thread.sp0;
 263
 264 #ifdef CONFIG_X86_32
 265         ctxt->event_callback_cs     = __KERNEL_CS;
 266         ctxt->failsafe_callback_cs  = __KERNEL_CS;
 267 #endif
 268         ctxt->event_callback_eip    = (unsigned long)xen_hypervisor_callback;
 269         ctxt->failsafe_callback_eip = (unsigned long)xen_failsafe_callback;
 270
 271         per_cpu(xen_cr3, cpu) = __pa(swapper_pg_dir);
 272         ctxt->ctrlreg[3] = xen_pfn_to_cr3(virt_to_mfn(swapper_pg_dir));
 273
 274         if (HYPERVISOR_vcpu_op(VCPUOP_initialise, cpu, ctxt))
 275                 BUG();
 276
 277         kfree(ctxt);
 278         return 0;
 279 }
 280
 281 static int __cpuinit xen_cpu_up(unsigned int cpu)
 282 {
 283         struct task_struct *idle = idle_task(cpu);
 284         int rc;
 285
 286 #ifdef CONFIG_X86_64
 287         /* Allocate node local memory for AP pdas */
 288         WARN_ON(cpu == 0);
 289         if (cpu > 0) {
 290                 rc = get_local_pda(cpu);
 291                 if (rc)
 292                         return rc;
 293         }
 294 #endif
 295
 296 #ifdef CONFIG_X86_32
 297         init_gdt(cpu);
 298         per_cpu(current_task, cpu) = idle;
 299         irq_ctx_init(cpu);
 300 #else
 301         cpu_pda(cpu)->pcurrent = idle;
 302         clear_tsk_thread_flag(idle, TIF_FORK);
 303 #endif
 304         xen_setup_timer(cpu);
 305         xen_init_lock_cpu(cpu);
 306
 307         per_cpu(cpu_state, cpu) = CPU_UP_PREPARE;
 308
 309         /* make sure interrupts start blocked */
 310         per_cpu(xen_vcpu, cpu)->evtchn_upcall_mask = 1;
 311
 312         rc = cpu_initialize_context(cpu, idle);
 313         if (rc)
 314                 return rc;
 315
 316         if (num_online_cpus() == 1)
 317                 alternatives_smp_switch(1);
 318
 319         rc = xen_smp_intr_init(cpu);
 320         if (rc)
 321                 return rc;
 322
 323         rc = HYPERVISOR_vcpu_op(VCPUOP_up, cpu, NULL);
 324         BUG_ON(rc);
 325
 326         while(per_cpu(cpu_state, cpu) != CPU_ONLINE) {
 327                 HYPERVISOR_sched_op(SCHEDOP_yield, 0);
 328                 barrier();
 329         }
 330
 331         return 0;
 332 }
 333
 334 static void xen_smp_cpus_done(unsigned int max_cpus)
 335 {
 336 }
 337
 338 #ifdef CONFIG_HOTPLUG_CPU
 339 static int xen_cpu_disable(void)
 340 {
 341         unsigned int cpu = smp_processor_id();
 342         if (cpu == 0)
 343                 return -EBUSY;
 344
 345         cpu_disable_common();
 346
 347         load_cr3(swapper_pg_dir);
 348         return 0;
 349 }
 350
 351 static void xen_cpu_die(unsigned int cpu)
 352 {
 353         while (HYPERVISOR_vcpu_op(VCPUOP_is_up, cpu, NULL)) {
 354                 current->state = TASK_UNINTERRUPTIBLE;
 355                 schedule_timeout(HZ/10);
 356         }
 357         unbind_from_irqhandler(per_cpu(resched_irq, cpu), NULL);
 358         unbind_from_irqhandler(per_cpu(callfunc_irq, cpu), NULL);
 359         unbind_from_irqhandler(per_cpu(debug_irq, cpu), NULL);
 360         unbind_from_irqhandler(per_cpu(callfuncsingle_irq, cpu), NULL);
 361         xen_uninit_lock_cpu(cpu);
 362         xen_teardown_timer(cpu);
 363
 364         if (num_online_cpus() == 1)
 365                 alternatives_smp_switch(0);
 366 }
 367
 368 static void __cpuinit xen_play_dead(void) /* used only with CPU_HOTPLUG */
 369 {
 370         play_dead_common();
 371         HYPERVISOR_vcpu_op(VCPUOP_down, smp_processor_id(), NULL);
 372         cpu_bringup();
 373 }
 374
 375 #else /* !CONFIG_HOTPLUG_CPU */
 376 static int xen_cpu_disable(void)
 377 {
 378         return -ENOSYS;
 379 }
 380
 381 static void xen_cpu_die(unsigned int cpu)
 382 {
 383         BUG();
 384 }
 385
 386 static void xen_play_dead(void)
 387 {
 388         BUG();
 389 }
 390
 391 #endif
 392 static void stop_self(void *v)
 393 {
 394         int cpu = smp_processor_id();
 395
 396         /* make sure we're not pinning something down */
 397         load_cr3(swapper_pg_dir);
 398         /* should set up a minimal gdt */
 399
 400         HYPERVISOR_vcpu_op(VCPUOP_down, cpu, NULL);
 401         BUG();
 402 }
 403
 404 static void xen_smp_send_stop(void)
 405 {
 406         smp_call_function(stop_self, NULL, 0);
 407 }
 408
 409 static void xen_smp_send_reschedule(int cpu)
 410 {
 411         xen_send_IPI_one(cpu, XEN_RESCHEDULE_VECTOR);
 412 }
 413
 414 static void xen_send_IPI_mask(const struct cpumask *mask,
 415                               enum ipi_vector vector)
 416 {
 417         unsigned cpu;
 418
 419         for_each_cpu_and(cpu, mask, cpu_online_mask)
 420                 xen_send_IPI_one(cpu, vector);
 421 }
 422
 423 static void xen_smp_send_call_function_ipi(const struct cpumask *mask)
 424 {
 425         int cpu;
 426
 427         xen_send_IPI_mask(mask, XEN_CALL_FUNCTION_VECTOR);
 428
 429         /* Make sure other vcpus get a chance to run if they need to. */
 430         for_each_cpu(cpu, mask) {
 431                 if (xen_vcpu_stolen(cpu)) {
 432                         HYPERVISOR_sched_op(SCHEDOP_yield, 0);
 433                         break;
 434                 }
 435         }
 436 }
 437
 438 static void xen_smp_send_call_function_single_ipi(int cpu)
 439 {
 440         xen_send_IPI_mask(cpumask_of(cpu),
 441                           XEN_CALL_FUNCTION_SINGLE_VECTOR);
 442 }
 443
 444 static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id)
 445 {
 446         irq_enter();
 447         generic_smp_call_function_interrupt();
 448 #ifdef CONFIG_X86_32
 449         __get_cpu_var(irq_stat).irq_call_count++;
 450 #else
 451         add_pda(irq_call_count, 1);
 452 #endif
 453         irq_exit();
 454
 455         return IRQ_HANDLED;
 456 }
 457
 458 static irqreturn_t xen_call_function_single_interrupt(int irq, void *dev_id)
 459 {
 460         irq_enter();
 461         generic_smp_call_function_single_interrupt();
 462 #ifdef CONFIG_X86_32
 463         __get_cpu_var(irq_stat).irq_call_count++;
 464 #else
 465         add_pda(irq_call_count, 1);
 466 #endif
 467         irq_exit();
 468
 469         return IRQ_HANDLED;
 470 }
 471
 472 static const struct smp_ops xen_smp_ops __initdata = {
 473         .smp_prepare_boot_cpu = xen_smp_prepare_boot_cpu,
 474         .smp_prepare_cpus = xen_smp_prepare_cpus,
 475         .smp_cpus_done = xen_smp_cpus_done,
 476
 477         .cpu_up = xen_cpu_up,
 478         .cpu_die = xen_cpu_die,
 479         .cpu_disable = xen_cpu_disable,
 480         .play_dead = xen_play_dead,
 481
 482         .smp_send_stop = xen_smp_send_stop,
 483         .smp_send_reschedule = xen_smp_send_reschedule,
 484
 485         .send_call_func_ipi = xen_smp_send_call_function_ipi,
 486         .send_call_func_single_ipi = xen_smp_send_call_function_single_ipi,
 487 };
 488
 489 void __init xen_smp_init(void)
 490 {
 491         smp_ops = xen_smp_ops;
 492         xen_fill_possible_map();
 493         xen_init_spinlocks();
 494 }