1 /*- 2 * Copyright (c) 2001, John Baldwin <jhb@FreeBSD.org>. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. Neither the name of the author nor the names of any co-contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30 /* 31 * This module holds the global variables and machine independent functions 32 * used for the kernel SMP support. 33 */ 34 35 #include <sys/cdefs.h> 36 __FBSDID("$FreeBSD$"); 37 38 #include <sys/param.h> 39 #include <sys/systm.h> 40 #include <sys/kernel.h> 41 #include <sys/ktr.h> 42 #include <sys/proc.h> 43 #include <sys/bus.h> 44 #include <sys/lock.h> 45 #include <sys/mutex.h> 46 #include <sys/pcpu.h> 47 #include <sys/smp.h> 48 #include <sys/sysctl.h> 49 50 #include <machine/cpu.h> 51 #include <machine/smp.h> 52 53 #include "opt_sched.h" 54 55 #ifdef SMP 56 volatile cpumask_t stopped_cpus; 57 volatile cpumask_t started_cpus; 58 cpumask_t idle_cpus_mask; 59 cpumask_t hlt_cpus_mask; 60 cpumask_t logical_cpus_mask; 61 62 void (*cpustop_restartfunc)(void); 63 #endif 64 /* This is used in modules that need to work in both SMP and UP. */ 65 cpumask_t all_cpus; 66 67 int mp_ncpus; 68 /* export this for libkvm consumers. */ 69 int mp_maxcpus = MAXCPU; 70 71 volatile int smp_started; 72 u_int mp_maxid; 73 74 SYSCTL_NODE(_kern, OID_AUTO, smp, CTLFLAG_RD, NULL, "Kernel SMP"); 75 76 SYSCTL_INT(_kern_smp, OID_AUTO, maxid, CTLFLAG_RD, &mp_maxid, 0, 77 "Max CPU ID."); 78 79 SYSCTL_INT(_kern_smp, OID_AUTO, maxcpus, CTLFLAG_RD, &mp_maxcpus, 0, 80 "Max number of CPUs that the system was compiled for."); 81 82 int smp_active = 0; /* are the APs allowed to run? */ 83 SYSCTL_INT(_kern_smp, OID_AUTO, active, CTLFLAG_RW, &smp_active, 0, 84 "Number of Auxillary Processors (APs) that were successfully started"); 85 86 int smp_disabled = 0; /* has smp been disabled? */ 87 SYSCTL_INT(_kern_smp, OID_AUTO, disabled, CTLFLAG_RDTUN, &smp_disabled, 0, 88 "SMP has been disabled from the loader"); 89 TUNABLE_INT("kern.smp.disabled", &smp_disabled); 90 91 int smp_cpus = 1; /* how many cpu's running */ 92 SYSCTL_INT(_kern_smp, OID_AUTO, cpus, CTLFLAG_RD, &smp_cpus, 0, 93 "Number of CPUs online"); 94 95 int smp_topology = 0; /* Which topology we're using. */ 96 SYSCTL_INT(_kern_smp, OID_AUTO, topology, CTLFLAG_RD, &smp_topology, 0, 97 "Topology override setting; 0 is default provided by hardware."); 98 TUNABLE_INT("kern.smp.topology", &smp_topology); 99 100 #ifdef SMP 101 /* Enable forwarding of a signal to a process running on a different CPU */ 102 static int forward_signal_enabled = 1; 103 SYSCTL_INT(_kern_smp, OID_AUTO, forward_signal_enabled, CTLFLAG_RW, 104 &forward_signal_enabled, 0, 105 "Forwarding of a signal to a process on a different CPU"); 106 107 /* Variables needed for SMP rendezvous. */ 108 static volatile int smp_rv_ncpus; 109 static void (*volatile smp_rv_setup_func)(void *arg); 110 static void (*volatile smp_rv_action_func)(void *arg); 111 static void (*volatile smp_rv_teardown_func)(void *arg); 112 static void *volatile smp_rv_func_arg; 113 static volatile int smp_rv_waiters[3]; 114 115 /* 116 * Shared mutex to restrict busywaits between smp_rendezvous() and 117 * smp(_targeted)_tlb_shootdown(). A deadlock occurs if both of these 118 * functions trigger at once and cause multiple CPUs to busywait with 119 * interrupts disabled. 120 */ 121 struct mtx smp_ipi_mtx; 122 123 /* 124 * Let the MD SMP code initialize mp_maxid very early if it can. 125 */ 126 static void 127 mp_setmaxid(void *dummy) 128 { 129 cpu_mp_setmaxid(); 130 } 131 SYSINIT(cpu_mp_setmaxid, SI_SUB_TUNABLES, SI_ORDER_FIRST, mp_setmaxid, NULL); 132 133 /* 134 * Call the MD SMP initialization code. 135 */ 136 static void 137 mp_start(void *dummy) 138 { 139 140 mtx_init(&smp_ipi_mtx, "smp rendezvous", NULL, MTX_SPIN); 141 142 /* Probe for MP hardware. */ 143 if (smp_disabled != 0 || cpu_mp_probe() == 0) { 144 mp_ncpus = 1; 145 all_cpus = PCPU_GET(cpumask); 146 return; 147 } 148 149 cpu_mp_start(); 150 printf("FreeBSD/SMP: Multiprocessor System Detected: %d CPUs\n", 151 mp_ncpus); 152 cpu_mp_announce(); 153 } 154 SYSINIT(cpu_mp, SI_SUB_CPU, SI_ORDER_THIRD, mp_start, NULL); 155 156 void 157 forward_signal(struct thread *td) 158 { 159 int id; 160 161 /* 162 * signotify() has already set TDF_ASTPENDING and TDF_NEEDSIGCHECK on 163 * this thread, so all we need to do is poke it if it is currently 164 * executing so that it executes ast(). 165 */ 166 THREAD_LOCK_ASSERT(td, MA_OWNED); 167 KASSERT(TD_IS_RUNNING(td), 168 ("forward_signal: thread is not TDS_RUNNING")); 169 170 CTR1(KTR_SMP, "forward_signal(%p)", td->td_proc); 171 172 if (!smp_started || cold || panicstr) 173 return; 174 if (!forward_signal_enabled) 175 return; 176 177 /* No need to IPI ourself. */ 178 if (td == curthread) 179 return; 180 181 id = td->td_oncpu; 182 if (id == NOCPU) 183 return; 184 ipi_cpu(id, IPI_AST); 185 } 186 187 /* 188 * When called the executing CPU will send an IPI to all other CPUs 189 * requesting that they halt execution. 190 * 191 * Usually (but not necessarily) called with 'other_cpus' as its arg. 192 * 193 * - Signals all CPUs in map to stop. 194 * - Waits for each to stop. 195 * 196 * Returns: 197 * -1: error 198 * 0: NA 199 * 1: ok 200 * 201 * XXX FIXME: this is not MP-safe, needs a lock to prevent multiple CPUs 202 * from executing at same time. 203 */ 204 static int 205 generic_stop_cpus(cpumask_t map, u_int type) 206 { 207 int i; 208 209 KASSERT(type == IPI_STOP || type == IPI_STOP_HARD, 210 ("%s: invalid stop type", __func__)); 211 212 if (!smp_started) 213 return 0; 214 215 CTR2(KTR_SMP, "stop_cpus(%x) with %u type", map, type); 216 217 /* send the stop IPI to all CPUs in map */ 218 ipi_selected(map, type); 219 220 i = 0; 221 while ((stopped_cpus & map) != map) { 222 /* spin */ 223 cpu_spinwait(); 224 i++; 225 #ifdef DIAGNOSTIC 226 if (i == 100000) { 227 printf("timeout stopping cpus\n"); 228 break; 229 } 230 #endif 231 } 232 233 return 1; 234 } 235 236 int 237 stop_cpus(cpumask_t map) 238 { 239 240 return (generic_stop_cpus(map, IPI_STOP)); 241 } 242 243 int 244 stop_cpus_hard(cpumask_t map) 245 { 246 247 return (generic_stop_cpus(map, IPI_STOP_HARD)); 248 } 249 250 #if defined(__amd64__) 251 /* 252 * When called the executing CPU will send an IPI to all other CPUs 253 * requesting that they halt execution. 254 * 255 * Usually (but not necessarily) called with 'other_cpus' as its arg. 256 * 257 * - Signals all CPUs in map to suspend. 258 * - Waits for each to suspend. 259 * 260 * Returns: 261 * -1: error 262 * 0: NA 263 * 1: ok 264 * 265 * XXX FIXME: this is not MP-safe, needs a lock to prevent multiple CPUs 266 * from executing at same time. 267 */ 268 int 269 suspend_cpus(cpumask_t map) 270 { 271 int i; 272 273 if (!smp_started) 274 return (0); 275 276 CTR1(KTR_SMP, "suspend_cpus(%x)", map); 277 278 /* send the suspend IPI to all CPUs in map */ 279 ipi_selected(map, IPI_SUSPEND); 280 281 i = 0; 282 while ((stopped_cpus & map) != map) { 283 /* spin */ 284 cpu_spinwait(); 285 i++; 286 #ifdef DIAGNOSTIC 287 if (i == 100000) { 288 printf("timeout suspending cpus\n"); 289 break; 290 } 291 #endif 292 } 293 294 return (1); 295 } 296 #endif 297 298 /* 299 * Called by a CPU to restart stopped CPUs. 300 * 301 * Usually (but not necessarily) called with 'stopped_cpus' as its arg. 302 * 303 * - Signals all CPUs in map to restart. 304 * - Waits for each to restart. 305 * 306 * Returns: 307 * -1: error 308 * 0: NA 309 * 1: ok 310 */ 311 int 312 restart_cpus(cpumask_t map) 313 { 314 315 if (!smp_started) 316 return 0; 317 318 CTR1(KTR_SMP, "restart_cpus(%x)", map); 319 320 /* signal other cpus to restart */ 321 atomic_store_rel_int(&started_cpus, map); 322 323 /* wait for each to clear its bit */ 324 while ((stopped_cpus & map) != 0) 325 cpu_spinwait(); 326 327 return 1; 328 } 329 330 /* 331 * All-CPU rendezvous. CPUs are signalled, all execute the setup function 332 * (if specified), rendezvous, execute the action function (if specified), 333 * rendezvous again, execute the teardown function (if specified), and then 334 * resume. 335 * 336 * Note that the supplied external functions _must_ be reentrant and aware 337 * that they are running in parallel and in an unknown lock context. 338 */ 339 void 340 smp_rendezvous_action(void) 341 { 342 void* local_func_arg = smp_rv_func_arg; 343 void (*local_setup_func)(void*) = smp_rv_setup_func; 344 void (*local_action_func)(void*) = smp_rv_action_func; 345 void (*local_teardown_func)(void*) = smp_rv_teardown_func; 346 347 /* Ensure we have up-to-date values. */ 348 atomic_add_acq_int(&smp_rv_waiters[0], 1); 349 while (smp_rv_waiters[0] < smp_rv_ncpus) 350 cpu_spinwait(); 351 352 /* setup function */ 353 if (local_setup_func != smp_no_rendevous_barrier) { 354 if (smp_rv_setup_func != NULL) 355 smp_rv_setup_func(smp_rv_func_arg); 356 357 /* spin on entry rendezvous */ 358 atomic_add_int(&smp_rv_waiters[1], 1); 359 while (smp_rv_waiters[1] < smp_rv_ncpus) 360 cpu_spinwait(); 361 } 362 363 /* action function */ 364 if (local_action_func != NULL) 365 local_action_func(local_func_arg); 366 367 /* spin on exit rendezvous */ 368 atomic_add_int(&smp_rv_waiters[2], 1); 369 if (local_teardown_func == smp_no_rendevous_barrier) 370 return; 371 while (smp_rv_waiters[2] < smp_rv_ncpus) 372 cpu_spinwait(); 373 374 /* teardown function */ 375 if (local_teardown_func != NULL) 376 local_teardown_func(local_func_arg); 377 } 378 379 void 380 smp_rendezvous_cpus(cpumask_t map, 381 void (* setup_func)(void *), 382 void (* action_func)(void *), 383 void (* teardown_func)(void *), 384 void *arg) 385 { 386 int i, ncpus = 0; 387 388 if (!smp_started) { 389 if (setup_func != NULL) 390 setup_func(arg); 391 if (action_func != NULL) 392 action_func(arg); 393 if (teardown_func != NULL) 394 teardown_func(arg); 395 return; 396 } 397 398 CPU_FOREACH(i) { 399 if (((1 << i) & map) != 0) 400 ncpus++; 401 } 402 if (ncpus == 0) 403 panic("ncpus is 0 with map=0x%x", map); 404 405 /* obtain rendezvous lock */ 406 mtx_lock_spin(&smp_ipi_mtx); 407 408 /* set static function pointers */ 409 smp_rv_ncpus = ncpus; 410 smp_rv_setup_func = setup_func; 411 smp_rv_action_func = action_func; 412 smp_rv_teardown_func = teardown_func; 413 smp_rv_func_arg = arg; 414 smp_rv_waiters[1] = 0; 415 smp_rv_waiters[2] = 0; 416 atomic_store_rel_int(&smp_rv_waiters[0], 0); 417 418 /* signal other processors, which will enter the IPI with interrupts off */ 419 ipi_selected(map & ~(1 << curcpu), IPI_RENDEZVOUS); 420 421 /* Check if the current CPU is in the map */ 422 if ((map & (1 << curcpu)) != 0) 423 smp_rendezvous_action(); 424 425 if (teardown_func == smp_no_rendevous_barrier) 426 while (atomic_load_acq_int(&smp_rv_waiters[2]) < ncpus) 427 cpu_spinwait(); 428 429 /* release lock */ 430 mtx_unlock_spin(&smp_ipi_mtx); 431 } 432 433 void 434 smp_rendezvous(void (* setup_func)(void *), 435 void (* action_func)(void *), 436 void (* teardown_func)(void *), 437 void *arg) 438 { 439 smp_rendezvous_cpus(all_cpus, setup_func, action_func, teardown_func, arg); 440 } 441 442 static struct cpu_group group[MAXCPU]; 443 444 struct cpu_group * 445 smp_topo(void) 446 { 447 struct cpu_group *top; 448 449 /* 450 * Check for a fake topology request for debugging purposes. 451 */ 452 switch (smp_topology) { 453 case 1: 454 /* Dual core with no sharing. */ 455 top = smp_topo_1level(CG_SHARE_NONE, 2, 0); 456 break; 457 case 2: 458 /* No topology, all cpus are equal. */ 459 top = smp_topo_none(); 460 break; 461 case 3: 462 /* Dual core with shared L2. */ 463 top = smp_topo_1level(CG_SHARE_L2, 2, 0); 464 break; 465 case 4: 466 /* quad core, shared l3 among each package, private l2. */ 467 top = smp_topo_1level(CG_SHARE_L3, 4, 0); 468 break; 469 case 5: 470 /* quad core, 2 dualcore parts on each package share l2. */ 471 top = smp_topo_2level(CG_SHARE_NONE, 2, CG_SHARE_L2, 2, 0); 472 break; 473 case 6: 474 /* Single-core 2xHTT */ 475 top = smp_topo_1level(CG_SHARE_L1, 2, CG_FLAG_HTT); 476 break; 477 case 7: 478 /* quad core with a shared l3, 8 threads sharing L2. */ 479 top = smp_topo_2level(CG_SHARE_L3, 4, CG_SHARE_L2, 8, 480 CG_FLAG_SMT); 481 break; 482 default: 483 /* Default, ask the system what it wants. */ 484 top = cpu_topo(); 485 break; 486 } 487 /* 488 * Verify the returned topology. 489 */ 490 if (top->cg_count != mp_ncpus) 491 panic("Built bad topology at %p. CPU count %d != %d", 492 top, top->cg_count, mp_ncpus); 493 if (top->cg_mask != all_cpus) 494 panic("Built bad topology at %p. CPU mask 0x%X != 0x%X", 495 top, top->cg_mask, all_cpus); 496 return (top); 497 } 498 499 struct cpu_group * 500 smp_topo_none(void) 501 { 502 struct cpu_group *top; 503 504 top = &group[0]; 505 top->cg_parent = NULL; 506 top->cg_child = NULL; 507 top->cg_mask = ~0U >> (32 - mp_ncpus); 508 top->cg_count = mp_ncpus; 509 top->cg_children = 0; 510 top->cg_level = CG_SHARE_NONE; 511 top->cg_flags = 0; 512 513 return (top); 514 } 515 516 static int 517 smp_topo_addleaf(struct cpu_group *parent, struct cpu_group *child, int share, 518 int count, int flags, int start) 519 { 520 cpumask_t mask; 521 int i; 522 523 for (mask = 0, i = 0; i < count; i++, start++) 524 mask |= (1 << start); 525 child->cg_parent = parent; 526 child->cg_child = NULL; 527 child->cg_children = 0; 528 child->cg_level = share; 529 child->cg_count = count; 530 child->cg_flags = flags; 531 child->cg_mask = mask; 532 parent->cg_children++; 533 for (; parent != NULL; parent = parent->cg_parent) { 534 if ((parent->cg_mask & child->cg_mask) != 0) 535 panic("Duplicate children in %p. mask 0x%X child 0x%X", 536 parent, parent->cg_mask, child->cg_mask); 537 parent->cg_mask |= child->cg_mask; 538 parent->cg_count += child->cg_count; 539 } 540 541 return (start); 542 } 543 544 struct cpu_group * 545 smp_topo_1level(int share, int count, int flags) 546 { 547 struct cpu_group *child; 548 struct cpu_group *top; 549 int packages; 550 int cpu; 551 int i; 552 553 cpu = 0; 554 top = &group[0]; 555 packages = mp_ncpus / count; 556 top->cg_child = child = &group[1]; 557 top->cg_level = CG_SHARE_NONE; 558 for (i = 0; i < packages; i++, child++) 559 cpu = smp_topo_addleaf(top, child, share, count, flags, cpu); 560 return (top); 561 } 562 563 struct cpu_group * 564 smp_topo_2level(int l2share, int l2count, int l1share, int l1count, 565 int l1flags) 566 { 567 struct cpu_group *top; 568 struct cpu_group *l1g; 569 struct cpu_group *l2g; 570 int cpu; 571 int i; 572 int j; 573 574 cpu = 0; 575 top = &group[0]; 576 l2g = &group[1]; 577 top->cg_child = l2g; 578 top->cg_level = CG_SHARE_NONE; 579 top->cg_children = mp_ncpus / (l2count * l1count); 580 l1g = l2g + top->cg_children; 581 for (i = 0; i < top->cg_children; i++, l2g++) { 582 l2g->cg_parent = top; 583 l2g->cg_child = l1g; 584 l2g->cg_level = l2share; 585 for (j = 0; j < l2count; j++, l1g++) 586 cpu = smp_topo_addleaf(l2g, l1g, l1share, l1count, 587 l1flags, cpu); 588 } 589 return (top); 590 } 591 592 593 struct cpu_group * 594 smp_topo_find(struct cpu_group *top, int cpu) 595 { 596 struct cpu_group *cg; 597 cpumask_t mask; 598 int children; 599 int i; 600 601 mask = (1 << cpu); 602 cg = top; 603 for (;;) { 604 if ((cg->cg_mask & mask) == 0) 605 return (NULL); 606 if (cg->cg_children == 0) 607 return (cg); 608 children = cg->cg_children; 609 for (i = 0, cg = cg->cg_child; i < children; cg++, i++) 610 if ((cg->cg_mask & mask) != 0) 611 break; 612 } 613 return (NULL); 614 } 615 #else /* !SMP */ 616 617 void 618 smp_rendezvous_cpus(cpumask_t map, 619 void (*setup_func)(void *), 620 void (*action_func)(void *), 621 void (*teardown_func)(void *), 622 void *arg) 623 { 624 if (setup_func != NULL) 625 setup_func(arg); 626 if (action_func != NULL) 627 action_func(arg); 628 if (teardown_func != NULL) 629 teardown_func(arg); 630 } 631 632 void 633 smp_rendezvous(void (*setup_func)(void *), 634 void (*action_func)(void *), 635 void (*teardown_func)(void *), 636 void *arg) 637 { 638 639 if (setup_func != NULL) 640 setup_func(arg); 641 if (action_func != NULL) 642 action_func(arg); 643 if (teardown_func != NULL) 644 teardown_func(arg); 645 } 646 647 /* 648 * Provide dummy SMP support for UP kernels. Modules that need to use SMP 649 * APIs will still work using this dummy support. 650 */ 651 static void 652 mp_setvariables_for_up(void *dummy) 653 { 654 mp_ncpus = 1; 655 mp_maxid = PCPU_GET(cpuid); 656 all_cpus = PCPU_GET(cpumask); 657 KASSERT(PCPU_GET(cpuid) == 0, ("UP must have a CPU ID of zero")); 658 } 659 SYSINIT(cpu_mp_setvariables, SI_SUB_TUNABLES, SI_ORDER_FIRST, 660 mp_setvariables_for_up, NULL); 661 #endif /* SMP */ 662 663 void 664 smp_no_rendevous_barrier(void *dummy) 665 { 666 #ifdef SMP 667 KASSERT((!smp_started),("smp_no_rendevous called and smp is started")); 668 #endif 669 } 670