git.oblomov.eu Git - linux-2.6/blob - drivers/xen/events.c

   1 /*
   2  * Xen event channels
   3  *
   4  * Xen models interrupts with abstract event channels.  Because each
   5  * domain gets 1024 event channels, but NR_IRQ is not that large, we
   6  * must dynamically map irqs<->event channels.  The event channels
   7  * interface with the rest of the kernel by defining a xen interrupt
   8  * chip.  When an event is recieved, it is mapped to an irq and sent
   9  * through the normal interrupt processing path.
  10  *
  11  * There are four kinds of events which can be mapped to an event
  12  * channel:
  13  *
  14  * 1. Inter-domain notifications.  This includes all the virtual
  15  *    device events, since they're driven by front-ends in another domain
  16  *    (typically dom0).
  17  * 2. VIRQs, typically used for timers.  These are per-cpu events.
  18  * 3. IPIs.
  19  * 4. Hardware interrupts. Not supported at present.
  20  *
  21  * Jeremy Fitzhardinge <jeremy@xensource.com>, XenSource Inc, 2007
  22  */
  23
  24 #include <linux/linkage.h>
  25 #include <linux/interrupt.h>
  26 #include <linux/irq.h>
  27 #include <linux/module.h>
  28 #include <linux/string.h>
  29
  30 #include <asm/ptrace.h>
  31 #include <asm/irq.h>
  32 #include <asm/sync_bitops.h>
  33 #include <asm/xen/hypercall.h>
  34 #include <asm/xen/hypervisor.h>
  35
  36 #include <xen/xen-ops.h>
  37 #include <xen/events.h>
  38 #include <xen/interface/xen.h>
  39 #include <xen/interface/event_channel.h>
  40
  41 /*
  42  * This lock protects updates to the following mapping and reference-count
  43  * arrays. The lock does not need to be acquired to read the mapping tables.
  44  */
  45 static DEFINE_SPINLOCK(irq_mapping_update_lock);
  46
  47 /* IRQ <-> VIRQ mapping. */
  48 static DEFINE_PER_CPU(int, virq_to_irq[NR_VIRQS]) = {[0 ... NR_VIRQS-1] = -1};
  49
  50 /* IRQ <-> IPI mapping */
  51 static DEFINE_PER_CPU(int, ipi_to_irq[XEN_NR_IPIS]) = {[0 ... XEN_NR_IPIS-1] = -1};
  52
  53 /* Packed IRQ information: binding type, sub-type index, and event channel. */
  54 struct packed_irq
  55 {
  56         unsigned short evtchn;
  57         unsigned char index;
  58         unsigned char type;
  59 };
  60
  61 static struct packed_irq irq_info[NR_IRQS];
  62
  63 /* Binding types. */
  64 enum {
  65         IRQT_UNBOUND,
  66         IRQT_PIRQ,
  67         IRQT_VIRQ,
  68         IRQT_IPI,
  69         IRQT_EVTCHN
  70 };
  71
  72 /* Convenient shorthand for packed representation of an unbound IRQ. */
  73 #define IRQ_UNBOUND     mk_irq_info(IRQT_UNBOUND, 0, 0)
  74
  75 static int evtchn_to_irq[NR_EVENT_CHANNELS] = {
  76         [0 ... NR_EVENT_CHANNELS-1] = -1
  77 };
  78 static unsigned long cpu_evtchn_mask[NR_CPUS][NR_EVENT_CHANNELS/BITS_PER_LONG];
  79 static u8 cpu_evtchn[NR_EVENT_CHANNELS];
  80
  81 /* Reference counts for bindings to IRQs. */
  82 static int irq_bindcount[NR_IRQS];
  83
  84 /* Xen will never allocate port zero for any purpose. */
  85 #define VALID_EVTCHN(chn)       ((chn) != 0)
  86
  87 /*
  88  * Force a proper event-channel callback from Xen after clearing the
  89  * callback mask. We do this in a very simple manner, by making a call
  90  * down into Xen. The pending flag will be checked by Xen on return.
  91  */
  92 void force_evtchn_callback(void)
  93 {
  94         (void)HYPERVISOR_xen_version(0, NULL);
  95 }
  96 EXPORT_SYMBOL_GPL(force_evtchn_callback);
  97
  98 static struct irq_chip xen_dynamic_chip;
  99
 100 /* Constructor for packed IRQ information. */
 101 static inline struct packed_irq mk_irq_info(u32 type, u32 index, u32 evtchn)
 102 {
 103         return (struct packed_irq) { evtchn, index, type };
 104 }
 105
 106 /*
 107  * Accessors for packed IRQ information.
 108  */
 109 static inline unsigned int evtchn_from_irq(int irq)
 110 {
 111         return irq_info[irq].evtchn;
 112 }
 113
 114 static inline unsigned int index_from_irq(int irq)
 115 {
 116         return irq_info[irq].index;
 117 }
 118
 119 static inline unsigned int type_from_irq(int irq)
 120 {
 121         return irq_info[irq].type;
 122 }
 123
 124 static inline unsigned long active_evtchns(unsigned int cpu,
 125                                            struct shared_info *sh,
 126                                            unsigned int idx)
 127 {
 128         return (sh->evtchn_pending[idx] &
 129                 cpu_evtchn_mask[cpu][idx] &
 130                 ~sh->evtchn_mask[idx]);
 131 }
 132
 133 static void bind_evtchn_to_cpu(unsigned int chn, unsigned int cpu)
 134 {
 135         int irq = evtchn_to_irq[chn];
 136
 137         BUG_ON(irq == -1);
 138 #ifdef CONFIG_SMP
 139         irq_desc[irq].affinity = cpumask_of_cpu(cpu);
 140 #endif
 141
 142         __clear_bit(chn, cpu_evtchn_mask[cpu_evtchn[chn]]);
 143         __set_bit(chn, cpu_evtchn_mask[cpu]);
 144
 145         cpu_evtchn[chn] = cpu;
 146 }
 147
 148 static void init_evtchn_cpu_bindings(void)
 149 {
 150 #ifdef CONFIG_SMP
 151         int i;
 152         /* By default all event channels notify CPU#0. */
 153         for (i = 0; i < NR_IRQS; i++)
 154                 irq_desc[i].affinity = cpumask_of_cpu(0);
 155 #endif
 156
 157         memset(cpu_evtchn, 0, sizeof(cpu_evtchn));
 158         memset(cpu_evtchn_mask[0], ~0, sizeof(cpu_evtchn_mask[0]));
 159 }
 160
 161 static inline unsigned int cpu_from_evtchn(unsigned int evtchn)
 162 {
 163         return cpu_evtchn[evtchn];
 164 }
 165
 166 static inline void clear_evtchn(int port)
 167 {
 168         struct shared_info *s = HYPERVISOR_shared_info;
 169         sync_clear_bit(port, &s->evtchn_pending[0]);
 170 }
 171
 172 static inline void set_evtchn(int port)
 173 {
 174         struct shared_info *s = HYPERVISOR_shared_info;
 175         sync_set_bit(port, &s->evtchn_pending[0]);
 176 }
 177
 178
 179 /**
 180  * notify_remote_via_irq - send event to remote end of event channel via irq
 181  * @irq: irq of event channel to send event to
 182  *
 183  * Unlike notify_remote_via_evtchn(), this is safe to use across
 184  * save/restore. Notifications on a broken connection are silently
 185  * dropped.
 186  */
 187 void notify_remote_via_irq(int irq)
 188 {
 189         int evtchn = evtchn_from_irq(irq);
 190
 191         if (VALID_EVTCHN(evtchn))
 192                 notify_remote_via_evtchn(evtchn);
 193 }
 194 EXPORT_SYMBOL_GPL(notify_remote_via_irq);
 195
 196 static void mask_evtchn(int port)
 197 {
 198         struct shared_info *s = HYPERVISOR_shared_info;
 199         sync_set_bit(port, &s->evtchn_mask[0]);
 200 }
 201
 202 static void unmask_evtchn(int port)
 203 {
 204         struct shared_info *s = HYPERVISOR_shared_info;
 205         unsigned int cpu = get_cpu();
 206
 207         BUG_ON(!irqs_disabled());
 208
 209         /* Slow path (hypercall) if this is a non-local port. */
 210         if (unlikely(cpu != cpu_from_evtchn(port))) {
 211                 struct evtchn_unmask unmask = { .port = port };
 212                 (void)HYPERVISOR_event_channel_op(EVTCHNOP_unmask, &unmask);
 213         } else {
 214                 struct vcpu_info *vcpu_info = __get_cpu_var(xen_vcpu);
 215
 216                 sync_clear_bit(port, &s->evtchn_mask[0]);
 217
 218                 /*
 219                  * The following is basically the equivalent of
 220                  * 'hw_resend_irq'. Just like a real IO-APIC we 'lose
 221                  * the interrupt edge' if the channel is masked.
 222                  */
 223                 if (sync_test_bit(port, &s->evtchn_pending[0]) &&
 224                     !sync_test_and_set_bit(port / BITS_PER_LONG,
 225                                            &vcpu_info->evtchn_pending_sel))
 226                         vcpu_info->evtchn_upcall_pending = 1;
 227         }
 228
 229         put_cpu();
 230 }
 231
 232 static int find_unbound_irq(void)
 233 {
 234         int irq;
 235
 236         /* Only allocate from dynirq range */
 237         for (irq = 0; irq < NR_IRQS; irq++)
 238                 if (irq_bindcount[irq] == 0)
 239                         break;
 240
 241         if (irq == NR_IRQS)
 242                 panic("No available IRQ to bind to: increase NR_IRQS!\n");
 243
 244         return irq;
 245 }
 246
 247 int bind_evtchn_to_irq(unsigned int evtchn)
 248 {
 249         int irq;
 250
 251         spin_lock(&irq_mapping_update_lock);
 252
 253         irq = evtchn_to_irq[evtchn];
 254
 255         if (irq == -1) {
 256                 irq = find_unbound_irq();
 257
 258                 dynamic_irq_init(irq);
 259                 set_irq_chip_and_handler_name(irq, &xen_dynamic_chip,
 260                                               handle_level_irq, "event");
 261
 262                 evtchn_to_irq[evtchn] = irq;
 263                 irq_info[irq] = mk_irq_info(IRQT_EVTCHN, 0, evtchn);
 264         }
 265
 266         irq_bindcount[irq]++;
 267
 268         spin_unlock(&irq_mapping_update_lock);
 269
 270         return irq;
 271 }
 272 EXPORT_SYMBOL_GPL(bind_evtchn_to_irq);
 273
 274 static int bind_ipi_to_irq(unsigned int ipi, unsigned int cpu)
 275 {
 276         struct evtchn_bind_ipi bind_ipi;
 277         int evtchn, irq;
 278
 279         spin_lock(&irq_mapping_update_lock);
 280
 281         irq = per_cpu(ipi_to_irq, cpu)[ipi];
 282         if (irq == -1) {
 283                 irq = find_unbound_irq();
 284                 if (irq < 0)
 285                         goto out;
 286
 287                 dynamic_irq_init(irq);
 288                 set_irq_chip_and_handler_name(irq, &xen_dynamic_chip,
 289                                               handle_level_irq, "ipi");
 290
 291                 bind_ipi.vcpu = cpu;
 292                 if (HYPERVISOR_event_channel_op(EVTCHNOP_bind_ipi,
 293                                                 &bind_ipi) != 0)
 294                         BUG();
 295                 evtchn = bind_ipi.port;
 296
 297                 evtchn_to_irq[evtchn] = irq;
 298                 irq_info[irq] = mk_irq_info(IRQT_IPI, ipi, evtchn);
 299
 300                 per_cpu(ipi_to_irq, cpu)[ipi] = irq;
 301
 302                 bind_evtchn_to_cpu(evtchn, cpu);
 303         }
 304
 305         irq_bindcount[irq]++;
 306
 307  out:
 308         spin_unlock(&irq_mapping_update_lock);
 309         return irq;
 310 }
 311
 312
 313 static int bind_virq_to_irq(unsigned int virq, unsigned int cpu)
 314 {
 315         struct evtchn_bind_virq bind_virq;
 316         int evtchn, irq;
 317
 318         spin_lock(&irq_mapping_update_lock);
 319
 320         irq = per_cpu(virq_to_irq, cpu)[virq];
 321
 322         if (irq == -1) {
 323                 bind_virq.virq = virq;
 324                 bind_virq.vcpu = cpu;
 325                 if (HYPERVISOR_event_channel_op(EVTCHNOP_bind_virq,
 326                                                 &bind_virq) != 0)
 327                         BUG();
 328                 evtchn = bind_virq.port;
 329
 330                 irq = find_unbound_irq();
 331
 332                 dynamic_irq_init(irq);
 333                 set_irq_chip_and_handler_name(irq, &xen_dynamic_chip,
 334                                               handle_level_irq, "virq");
 335
 336                 evtchn_to_irq[evtchn] = irq;
 337                 irq_info[irq] = mk_irq_info(IRQT_VIRQ, virq, evtchn);
 338
 339                 per_cpu(virq_to_irq, cpu)[virq] = irq;
 340
 341                 bind_evtchn_to_cpu(evtchn, cpu);
 342         }
 343
 344         irq_bindcount[irq]++;
 345
 346         spin_unlock(&irq_mapping_update_lock);
 347
 348         return irq;
 349 }
 350
 351 static void unbind_from_irq(unsigned int irq)
 352 {
 353         struct evtchn_close close;
 354         int evtchn = evtchn_from_irq(irq);
 355
 356         spin_lock(&irq_mapping_update_lock);
 357
 358         if (VALID_EVTCHN(evtchn) && (--irq_bindcount[irq] == 0)) {
 359                 close.port = evtchn;
 360                 if (HYPERVISOR_event_channel_op(EVTCHNOP_close, &close) != 0)
 361                         BUG();
 362
 363                 switch (type_from_irq(irq)) {
 364                 case IRQT_VIRQ:
 365                         per_cpu(virq_to_irq, cpu_from_evtchn(evtchn))
 366                                 [index_from_irq(irq)] = -1;
 367                         break;
 368                 default:
 369                         break;
 370                 }
 371
 372                 /* Closed ports are implicitly re-bound to VCPU0. */
 373                 bind_evtchn_to_cpu(evtchn, 0);
 374
 375                 evtchn_to_irq[evtchn] = -1;
 376                 irq_info[irq] = IRQ_UNBOUND;
 377
 378                 dynamic_irq_init(irq);
 379         }
 380
 381         spin_unlock(&irq_mapping_update_lock);
 382 }
 383
 384 int bind_evtchn_to_irqhandler(unsigned int evtchn,
 385                               irq_handler_t handler,
 386                               unsigned long irqflags,
 387                               const char *devname, void *dev_id)
 388 {
 389         unsigned int irq;
 390         int retval;
 391
 392         irq = bind_evtchn_to_irq(evtchn);
 393         retval = request_irq(irq, handler, irqflags, devname, dev_id);
 394         if (retval != 0) {
 395                 unbind_from_irq(irq);
 396                 return retval;
 397         }
 398
 399         return irq;
 400 }
 401 EXPORT_SYMBOL_GPL(bind_evtchn_to_irqhandler);
 402
 403 int bind_virq_to_irqhandler(unsigned int virq, unsigned int cpu,
 404                             irq_handler_t handler,
 405                             unsigned long irqflags, const char *devname, void *dev_id)
 406 {
 407         unsigned int irq;
 408         int retval;
 409
 410         irq = bind_virq_to_irq(virq, cpu);
 411         retval = request_irq(irq, handler, irqflags, devname, dev_id);
 412         if (retval != 0) {
 413                 unbind_from_irq(irq);
 414                 return retval;
 415         }
 416
 417         return irq;
 418 }
 419 EXPORT_SYMBOL_GPL(bind_virq_to_irqhandler);
 420
 421 int bind_ipi_to_irqhandler(enum ipi_vector ipi,
 422                            unsigned int cpu,
 423                            irq_handler_t handler,
 424                            unsigned long irqflags,
 425                            const char *devname,
 426                            void *dev_id)
 427 {
 428         int irq, retval;
 429
 430         irq = bind_ipi_to_irq(ipi, cpu);
 431         if (irq < 0)
 432                 return irq;
 433
 434         retval = request_irq(irq, handler, irqflags, devname, dev_id);
 435         if (retval != 0) {
 436                 unbind_from_irq(irq);
 437                 return retval;
 438         }
 439
 440         return irq;
 441 }
 442
 443 void unbind_from_irqhandler(unsigned int irq, void *dev_id)
 444 {
 445         free_irq(irq, dev_id);
 446         unbind_from_irq(irq);
 447 }
 448 EXPORT_SYMBOL_GPL(unbind_from_irqhandler);
 449
 450 void xen_send_IPI_one(unsigned int cpu, enum ipi_vector vector)
 451 {
 452         int irq = per_cpu(ipi_to_irq, cpu)[vector];
 453         BUG_ON(irq < 0);
 454         notify_remote_via_irq(irq);
 455 }
 456
 457 irqreturn_t xen_debug_interrupt(int irq, void *dev_id)
 458 {
 459         struct shared_info *sh = HYPERVISOR_shared_info;
 460         int cpu = smp_processor_id();
 461         int i;
 462         unsigned long flags;
 463         static DEFINE_SPINLOCK(debug_lock);
 464
 465         spin_lock_irqsave(&debug_lock, flags);
 466
 467         printk("vcpu %d\n  ", cpu);
 468
 469         for_each_online_cpu(i) {
 470                 struct vcpu_info *v = per_cpu(xen_vcpu, i);
 471                 printk("%d: masked=%d pending=%d event_sel %08lx\n  ", i,
 472                         (get_irq_regs() && i == cpu) ? !(get_irq_regs()->flags & X86_EFLAGS_IF) : v->evtchn_upcall_mask,
 473                         v->evtchn_upcall_pending,
 474                         v->evtchn_pending_sel);
 475         }
 476         printk("pending:\n   ");
 477         for(i = ARRAY_SIZE(sh->evtchn_pending)-1; i >= 0; i--)
 478                 printk("%08lx%s", sh->evtchn_pending[i],
 479                         i % 8 == 0 ? "\n   " : " ");
 480         printk("\nmasks:\n   ");
 481         for(i = ARRAY_SIZE(sh->evtchn_mask)-1; i >= 0; i--)
 482                 printk("%08lx%s", sh->evtchn_mask[i],
 483                         i % 8 == 0 ? "\n   " : " ");
 484
 485         printk("\nunmasked:\n   ");
 486         for(i = ARRAY_SIZE(sh->evtchn_mask)-1; i >= 0; i--)
 487                 printk("%08lx%s", sh->evtchn_pending[i] & ~sh->evtchn_mask[i],
 488                         i % 8 == 0 ? "\n   " : " ");
 489
 490         printk("\npending list:\n");
 491         for(i = 0; i < NR_EVENT_CHANNELS; i++) {
 492                 if (sync_test_bit(i, sh->evtchn_pending)) {
 493                         printk("  %d: event %d -> irq %d\n",
 494                                 cpu_evtchn[i], i,
 495                                 evtchn_to_irq[i]);
 496                 }
 497         }
 498
 499         spin_unlock_irqrestore(&debug_lock, flags);
 500
 501         return IRQ_HANDLED;
 502 }
 503
 504
 505 /*
 506  * Search the CPUs pending events bitmasks.  For each one found, map
 507  * the event number to an irq, and feed it into do_IRQ() for
 508  * handling.
 509  *
 510  * Xen uses a two-level bitmap to speed searching.  The first level is
 511  * a bitset of words which contain pending event bits.  The second
 512  * level is a bitset of pending events themselves.
 513  */
 514 void xen_evtchn_do_upcall(struct pt_regs *regs)
 515 {
 516         int cpu = get_cpu();
 517         struct shared_info *s = HYPERVISOR_shared_info;
 518         struct vcpu_info *vcpu_info = __get_cpu_var(xen_vcpu);
 519         static DEFINE_PER_CPU(unsigned, nesting_count);
 520         unsigned count;
 521
 522         do {
 523                 unsigned long pending_words;
 524
 525                 vcpu_info->evtchn_upcall_pending = 0;
 526
 527                 if (__get_cpu_var(nesting_count)++)
 528                         goto out;
 529
 530                 /* NB. No need for a barrier here -- XCHG is a barrier on x86. */
 531                 pending_words = xchg(&vcpu_info->evtchn_pending_sel, 0);
 532                 while (pending_words != 0) {
 533                         unsigned long pending_bits;
 534                         int word_idx = __ffs(pending_words);
 535                         pending_words &= ~(1UL << word_idx);
 536
 537                         while ((pending_bits = active_evtchns(cpu, s, word_idx)) != 0) {
 538                                 int bit_idx = __ffs(pending_bits);
 539                                 int port = (word_idx * BITS_PER_LONG) + bit_idx;
 540                                 int irq = evtchn_to_irq[port];
 541
 542                                 if (irq != -1) {
 543                                         regs->orig_ax = ~irq;
 544                                         do_IRQ(regs);
 545                                 }
 546                         }
 547                 }
 548
 549                 BUG_ON(!irqs_disabled());
 550
 551                 count = __get_cpu_var(nesting_count);
 552                 __get_cpu_var(nesting_count) = 0;
 553         } while(count != 1);
 554
 555 out:
 556         put_cpu();
 557 }
 558
 559 /* Rebind an evtchn so that it gets delivered to a specific cpu */
 560 static void rebind_irq_to_cpu(unsigned irq, unsigned tcpu)
 561 {
 562         struct evtchn_bind_vcpu bind_vcpu;
 563         int evtchn = evtchn_from_irq(irq);
 564
 565         if (!VALID_EVTCHN(evtchn))
 566                 return;
 567
 568         /* Send future instances of this interrupt to other vcpu. */
 569         bind_vcpu.port = evtchn;
 570         bind_vcpu.vcpu = tcpu;
 571
 572         /*
 573          * If this fails, it usually just indicates that we're dealing with a
 574          * virq or IPI channel, which don't actually need to be rebound. Ignore
 575          * it, but don't do the xenlinux-level rebind in that case.
 576          */
 577         if (HYPERVISOR_event_channel_op(EVTCHNOP_bind_vcpu, &bind_vcpu) >= 0)
 578                 bind_evtchn_to_cpu(evtchn, tcpu);
 579 }
 580
 581
 582 static void set_affinity_irq(unsigned irq, cpumask_t dest)
 583 {
 584         unsigned tcpu = first_cpu(dest);
 585         rebind_irq_to_cpu(irq, tcpu);
 586 }
 587
 588 static void enable_dynirq(unsigned int irq)
 589 {
 590         int evtchn = evtchn_from_irq(irq);
 591
 592         if (VALID_EVTCHN(evtchn))
 593                 unmask_evtchn(evtchn);
 594 }
 595
 596 static void disable_dynirq(unsigned int irq)
 597 {
 598         int evtchn = evtchn_from_irq(irq);
 599
 600         if (VALID_EVTCHN(evtchn))
 601                 mask_evtchn(evtchn);
 602 }
 603
 604 static void ack_dynirq(unsigned int irq)
 605 {
 606         int evtchn = evtchn_from_irq(irq);
 607
 608         move_native_irq(irq);
 609
 610         if (VALID_EVTCHN(evtchn))
 611                 clear_evtchn(evtchn);
 612 }
 613
 614 static int retrigger_dynirq(unsigned int irq)
 615 {
 616         int evtchn = evtchn_from_irq(irq);
 617         struct shared_info *sh = HYPERVISOR_shared_info;
 618         int ret = 0;
 619
 620         if (VALID_EVTCHN(evtchn)) {
 621                 int masked;
 622
 623                 masked = sync_test_and_set_bit(evtchn, sh->evtchn_mask);
 624                 sync_set_bit(evtchn, sh->evtchn_pending);
 625                 if (!masked)
 626                         unmask_evtchn(evtchn);
 627                 ret = 1;
 628         }
 629
 630         return ret;
 631 }
 632
 633 static struct irq_chip xen_dynamic_chip __read_mostly = {
 634         .name           = "xen-dyn",
 635         .mask           = disable_dynirq,
 636         .unmask         = enable_dynirq,
 637         .ack            = ack_dynirq,
 638         .set_affinity   = set_affinity_irq,
 639         .retrigger      = retrigger_dynirq,
 640 };
 641
 642 void __init xen_init_IRQ(void)
 643 {
 644         int i;
 645
 646         init_evtchn_cpu_bindings();
 647
 648         /* No event channels are 'live' right now. */
 649         for (i = 0; i < NR_EVENT_CHANNELS; i++)
 650                 mask_evtchn(i);
 651
 652         /* Dynamic IRQ space is currently unbound. Zero the refcnts. */
 653         for (i = 0; i < NR_IRQS; i++)
 654                 irq_bindcount[i] = 0;
 655
 656         irq_ctx_init(smp_processor_id());
 657 }