1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2001, John Baldwin <jhb@FreeBSD.org>. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 28 /* 29 * This module holds the global variables and machine independent functions 30 * used for the kernel SMP support. 31 */ 32 33 #include <sys/cdefs.h> 34 __FBSDID("$FreeBSD$"); 35 36 #include <sys/param.h> 37 #include <sys/systm.h> 38 #include <sys/kernel.h> 39 #include <sys/ktr.h> 40 #include <sys/proc.h> 41 #include <sys/bus.h> 42 #include <sys/lock.h> 43 #include <sys/malloc.h> 44 #include <sys/mutex.h> 45 #include <sys/pcpu.h> 46 #include <sys/sched.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 MALLOC_DEFINE(M_TOPO, "toponodes", "SMP topology data"); 57 58 volatile cpuset_t stopped_cpus; 59 volatile cpuset_t started_cpus; 60 volatile cpuset_t suspended_cpus; 61 cpuset_t hlt_cpus_mask; 62 cpuset_t logical_cpus_mask; 63 64 void (*cpustop_restartfunc)(void); 65 #endif 66 67 static int sysctl_kern_smp_active(SYSCTL_HANDLER_ARGS); 68 69 /* This is used in modules that need to work in both SMP and UP. */ 70 cpuset_t all_cpus; 71 72 int mp_ncpus; 73 /* export this for libkvm consumers. */ 74 int mp_maxcpus = MAXCPU; 75 76 volatile int smp_started; 77 u_int mp_maxid; 78 79 static SYSCTL_NODE(_kern, OID_AUTO, smp, 80 CTLFLAG_RD | CTLFLAG_CAPRD | CTLFLAG_MPSAFE, NULL, 81 "Kernel SMP"); 82 83 SYSCTL_INT(_kern_smp, OID_AUTO, maxid, CTLFLAG_RD|CTLFLAG_CAPRD, &mp_maxid, 0, 84 "Max CPU ID."); 85 86 SYSCTL_INT(_kern_smp, OID_AUTO, maxcpus, CTLFLAG_RD|CTLFLAG_CAPRD, &mp_maxcpus, 87 0, "Max number of CPUs that the system was compiled for."); 88 89 SYSCTL_PROC(_kern_smp, OID_AUTO, active, CTLFLAG_RD|CTLTYPE_INT|CTLFLAG_MPSAFE, 90 NULL, 0, sysctl_kern_smp_active, "I", 91 "Indicates system is running in SMP mode"); 92 93 int smp_disabled = 0; /* has smp been disabled? */ 94 SYSCTL_INT(_kern_smp, OID_AUTO, disabled, CTLFLAG_RDTUN|CTLFLAG_CAPRD, 95 &smp_disabled, 0, "SMP has been disabled from the loader"); 96 97 int smp_cpus = 1; /* how many cpu's running */ 98 SYSCTL_INT(_kern_smp, OID_AUTO, cpus, CTLFLAG_RD|CTLFLAG_CAPRD, &smp_cpus, 0, 99 "Number of CPUs online"); 100 101 int smp_threads_per_core = 1; /* how many SMT threads are running per core */ 102 SYSCTL_INT(_kern_smp, OID_AUTO, threads_per_core, CTLFLAG_RD|CTLFLAG_CAPRD, 103 &smp_threads_per_core, 0, "Number of SMT threads online per core"); 104 105 int mp_ncores = -1; /* how many physical cores running */ 106 SYSCTL_INT(_kern_smp, OID_AUTO, cores, CTLFLAG_RD|CTLFLAG_CAPRD, &mp_ncores, 0, 107 "Number of physical cores online"); 108 109 int smp_topology = 0; /* Which topology we're using. */ 110 SYSCTL_INT(_kern_smp, OID_AUTO, topology, CTLFLAG_RDTUN, &smp_topology, 0, 111 "Topology override setting; 0 is default provided by hardware."); 112 113 #ifdef SMP 114 /* Enable forwarding of a signal to a process running on a different CPU */ 115 static int forward_signal_enabled = 1; 116 SYSCTL_INT(_kern_smp, OID_AUTO, forward_signal_enabled, CTLFLAG_RW, 117 &forward_signal_enabled, 0, 118 "Forwarding of a signal to a process on a different CPU"); 119 120 /* Variables needed for SMP rendezvous. */ 121 static volatile int smp_rv_ncpus; 122 static void (*volatile smp_rv_setup_func)(void *arg); 123 static void (*volatile smp_rv_action_func)(void *arg); 124 static void (*volatile smp_rv_teardown_func)(void *arg); 125 static void *volatile smp_rv_func_arg; 126 static volatile int smp_rv_waiters[4]; 127 128 /* 129 * Shared mutex to restrict busywaits between smp_rendezvous() and 130 * smp(_targeted)_tlb_shootdown(). A deadlock occurs if both of these 131 * functions trigger at once and cause multiple CPUs to busywait with 132 * interrupts disabled. 133 */ 134 struct mtx smp_ipi_mtx; 135 136 /* 137 * Let the MD SMP code initialize mp_maxid very early if it can. 138 */ 139 static void 140 mp_setmaxid(void *dummy) 141 { 142 143 cpu_mp_setmaxid(); 144 145 KASSERT(mp_ncpus >= 1, ("%s: CPU count < 1", __func__)); 146 KASSERT(mp_ncpus > 1 || mp_maxid == 0, 147 ("%s: one CPU but mp_maxid is not zero", __func__)); 148 KASSERT(mp_maxid >= mp_ncpus - 1, 149 ("%s: counters out of sync: max %d, count %d", __func__, 150 mp_maxid, mp_ncpus)); 151 } 152 SYSINIT(cpu_mp_setmaxid, SI_SUB_TUNABLES, SI_ORDER_FIRST, mp_setmaxid, NULL); 153 154 /* 155 * Call the MD SMP initialization code. 156 */ 157 static void 158 mp_start(void *dummy) 159 { 160 161 mtx_init(&smp_ipi_mtx, "smp rendezvous", NULL, MTX_SPIN); 162 163 /* Probe for MP hardware. */ 164 if (smp_disabled != 0 || cpu_mp_probe() == 0) { 165 mp_ncores = 1; 166 mp_ncpus = 1; 167 CPU_SETOF(PCPU_GET(cpuid), &all_cpus); 168 return; 169 } 170 171 cpu_mp_start(); 172 printf("FreeBSD/SMP: Multiprocessor System Detected: %d CPUs\n", 173 mp_ncpus); 174 175 /* Provide a default for most architectures that don't have SMT/HTT. */ 176 if (mp_ncores < 0) 177 mp_ncores = mp_ncpus; 178 179 cpu_mp_announce(); 180 } 181 SYSINIT(cpu_mp, SI_SUB_CPU, SI_ORDER_THIRD, mp_start, NULL); 182 183 void 184 forward_signal(struct thread *td) 185 { 186 int id; 187 188 /* 189 * signotify() has already set TDF_ASTPENDING and TDF_NEEDSIGCHECK on 190 * this thread, so all we need to do is poke it if it is currently 191 * executing so that it executes ast(). 192 */ 193 THREAD_LOCK_ASSERT(td, MA_OWNED); 194 KASSERT(TD_IS_RUNNING(td), 195 ("forward_signal: thread is not TDS_RUNNING")); 196 197 CTR1(KTR_SMP, "forward_signal(%p)", td->td_proc); 198 199 if (!smp_started || cold || KERNEL_PANICKED()) 200 return; 201 if (!forward_signal_enabled) 202 return; 203 204 /* No need to IPI ourself. */ 205 if (td == curthread) 206 return; 207 208 id = td->td_oncpu; 209 if (id == NOCPU) 210 return; 211 ipi_cpu(id, IPI_AST); 212 } 213 214 /* 215 * When called the executing CPU will send an IPI to all other CPUs 216 * requesting that they halt execution. 217 * 218 * Usually (but not necessarily) called with 'other_cpus' as its arg. 219 * 220 * - Signals all CPUs in map to stop. 221 * - Waits for each to stop. 222 * 223 * Returns: 224 * -1: error 225 * 0: NA 226 * 1: ok 227 * 228 */ 229 #if defined(__amd64__) || defined(__i386__) 230 #define X86 1 231 #else 232 #define X86 0 233 #endif 234 static int 235 generic_stop_cpus(cpuset_t map, u_int type) 236 { 237 #ifdef KTR 238 char cpusetbuf[CPUSETBUFSIZ]; 239 #endif 240 static volatile u_int stopping_cpu = NOCPU; 241 int i; 242 volatile cpuset_t *cpus; 243 244 KASSERT( 245 type == IPI_STOP || type == IPI_STOP_HARD 246 #if X86 247 || type == IPI_SUSPEND 248 #endif 249 , ("%s: invalid stop type", __func__)); 250 251 if (!smp_started) 252 return (0); 253 254 CTR2(KTR_SMP, "stop_cpus(%s) with %u type", 255 cpusetobj_strprint(cpusetbuf, &map), type); 256 257 #if X86 258 /* 259 * When suspending, ensure there are are no IPIs in progress. 260 * IPIs that have been issued, but not yet delivered (e.g. 261 * not pending on a vCPU when running under virtualization) 262 * will be lost, violating FreeBSD's assumption of reliable 263 * IPI delivery. 264 */ 265 if (type == IPI_SUSPEND) 266 mtx_lock_spin(&smp_ipi_mtx); 267 #endif 268 269 #if X86 270 if (!nmi_is_broadcast || nmi_kdb_lock == 0) { 271 #endif 272 if (stopping_cpu != PCPU_GET(cpuid)) 273 while (atomic_cmpset_int(&stopping_cpu, NOCPU, 274 PCPU_GET(cpuid)) == 0) 275 while (stopping_cpu != NOCPU) 276 cpu_spinwait(); /* spin */ 277 278 /* send the stop IPI to all CPUs in map */ 279 ipi_selected(map, type); 280 #if X86 281 } 282 #endif 283 284 #if X86 285 if (type == IPI_SUSPEND) 286 cpus = &suspended_cpus; 287 else 288 #endif 289 cpus = &stopped_cpus; 290 291 i = 0; 292 while (!CPU_SUBSET(cpus, &map)) { 293 /* spin */ 294 cpu_spinwait(); 295 i++; 296 if (i == 100000000) { 297 printf("timeout stopping cpus\n"); 298 break; 299 } 300 } 301 302 #if X86 303 if (type == IPI_SUSPEND) 304 mtx_unlock_spin(&smp_ipi_mtx); 305 #endif 306 307 stopping_cpu = NOCPU; 308 return (1); 309 } 310 311 int 312 stop_cpus(cpuset_t map) 313 { 314 315 return (generic_stop_cpus(map, IPI_STOP)); 316 } 317 318 int 319 stop_cpus_hard(cpuset_t map) 320 { 321 322 return (generic_stop_cpus(map, IPI_STOP_HARD)); 323 } 324 325 #if X86 326 int 327 suspend_cpus(cpuset_t map) 328 { 329 330 return (generic_stop_cpus(map, IPI_SUSPEND)); 331 } 332 #endif 333 334 /* 335 * Called by a CPU to restart stopped CPUs. 336 * 337 * Usually (but not necessarily) called with 'stopped_cpus' as its arg. 338 * 339 * - Signals all CPUs in map to restart. 340 * - Waits for each to restart. 341 * 342 * Returns: 343 * -1: error 344 * 0: NA 345 * 1: ok 346 */ 347 static int 348 generic_restart_cpus(cpuset_t map, u_int type) 349 { 350 #ifdef KTR 351 char cpusetbuf[CPUSETBUFSIZ]; 352 #endif 353 volatile cpuset_t *cpus; 354 355 #if X86 356 KASSERT(type == IPI_STOP || type == IPI_STOP_HARD 357 || type == IPI_SUSPEND, ("%s: invalid stop type", __func__)); 358 359 if (!smp_started) 360 return (0); 361 362 CTR1(KTR_SMP, "restart_cpus(%s)", cpusetobj_strprint(cpusetbuf, &map)); 363 364 if (type == IPI_SUSPEND) 365 cpus = &resuming_cpus; 366 else 367 cpus = &stopped_cpus; 368 369 /* signal other cpus to restart */ 370 if (type == IPI_SUSPEND) 371 CPU_COPY_STORE_REL(&map, &toresume_cpus); 372 else 373 CPU_COPY_STORE_REL(&map, &started_cpus); 374 375 /* 376 * Wake up any CPUs stopped with MWAIT. From MI code we can't tell if 377 * MONITOR/MWAIT is enabled, but the potentially redundant writes are 378 * relatively inexpensive. 379 */ 380 if (type == IPI_STOP) { 381 struct monitorbuf *mb; 382 u_int id; 383 384 CPU_FOREACH(id) { 385 if (!CPU_ISSET(id, &map)) 386 continue; 387 388 mb = &pcpu_find(id)->pc_monitorbuf; 389 atomic_store_int(&mb->stop_state, 390 MONITOR_STOPSTATE_RUNNING); 391 } 392 } 393 394 if (!nmi_is_broadcast || nmi_kdb_lock == 0) { 395 /* wait for each to clear its bit */ 396 while (CPU_OVERLAP(cpus, &map)) 397 cpu_spinwait(); 398 } 399 #else /* !X86 */ 400 KASSERT(type == IPI_STOP || type == IPI_STOP_HARD, 401 ("%s: invalid stop type", __func__)); 402 403 if (!smp_started) 404 return (0); 405 406 CTR1(KTR_SMP, "restart_cpus(%s)", cpusetobj_strprint(cpusetbuf, &map)); 407 408 cpus = &stopped_cpus; 409 410 /* signal other cpus to restart */ 411 CPU_COPY_STORE_REL(&map, &started_cpus); 412 413 /* wait for each to clear its bit */ 414 while (CPU_OVERLAP(cpus, &map)) 415 cpu_spinwait(); 416 #endif 417 return (1); 418 } 419 420 int 421 restart_cpus(cpuset_t map) 422 { 423 424 return (generic_restart_cpus(map, IPI_STOP)); 425 } 426 427 #if X86 428 int 429 resume_cpus(cpuset_t map) 430 { 431 432 return (generic_restart_cpus(map, IPI_SUSPEND)); 433 } 434 #endif 435 #undef X86 436 437 /* 438 * All-CPU rendezvous. CPUs are signalled, all execute the setup function 439 * (if specified), rendezvous, execute the action function (if specified), 440 * rendezvous again, execute the teardown function (if specified), and then 441 * resume. 442 * 443 * Note that the supplied external functions _must_ be reentrant and aware 444 * that they are running in parallel and in an unknown lock context. 445 */ 446 void 447 smp_rendezvous_action(void) 448 { 449 struct thread *td; 450 void *local_func_arg; 451 void (*local_setup_func)(void*); 452 void (*local_action_func)(void*); 453 void (*local_teardown_func)(void*); 454 #ifdef INVARIANTS 455 int owepreempt; 456 #endif 457 458 /* Ensure we have up-to-date values. */ 459 atomic_add_acq_int(&smp_rv_waiters[0], 1); 460 while (smp_rv_waiters[0] < smp_rv_ncpus) 461 cpu_spinwait(); 462 463 /* Fetch rendezvous parameters after acquire barrier. */ 464 local_func_arg = smp_rv_func_arg; 465 local_setup_func = smp_rv_setup_func; 466 local_action_func = smp_rv_action_func; 467 local_teardown_func = smp_rv_teardown_func; 468 469 /* 470 * Use a nested critical section to prevent any preemptions 471 * from occurring during a rendezvous action routine. 472 * Specifically, if a rendezvous handler is invoked via an IPI 473 * and the interrupted thread was in the critical_exit() 474 * function after setting td_critnest to 0 but before 475 * performing a deferred preemption, this routine can be 476 * invoked with td_critnest set to 0 and td_owepreempt true. 477 * In that case, a critical_exit() during the rendezvous 478 * action would trigger a preemption which is not permitted in 479 * a rendezvous action. To fix this, wrap all of the 480 * rendezvous action handlers in a critical section. We 481 * cannot use a regular critical section however as having 482 * critical_exit() preempt from this routine would also be 483 * problematic (the preemption must not occur before the IPI 484 * has been acknowledged via an EOI). Instead, we 485 * intentionally ignore td_owepreempt when leaving the 486 * critical section. This should be harmless because we do 487 * not permit rendezvous action routines to schedule threads, 488 * and thus td_owepreempt should never transition from 0 to 1 489 * during this routine. 490 */ 491 td = curthread; 492 td->td_critnest++; 493 #ifdef INVARIANTS 494 owepreempt = td->td_owepreempt; 495 #endif 496 497 /* 498 * If requested, run a setup function before the main action 499 * function. Ensure all CPUs have completed the setup 500 * function before moving on to the action function. 501 */ 502 if (local_setup_func != smp_no_rendezvous_barrier) { 503 if (smp_rv_setup_func != NULL) 504 smp_rv_setup_func(smp_rv_func_arg); 505 atomic_add_int(&smp_rv_waiters[1], 1); 506 while (smp_rv_waiters[1] < smp_rv_ncpus) 507 cpu_spinwait(); 508 } 509 510 if (local_action_func != NULL) 511 local_action_func(local_func_arg); 512 513 if (local_teardown_func != smp_no_rendezvous_barrier) { 514 /* 515 * Signal that the main action has been completed. If a 516 * full exit rendezvous is requested, then all CPUs will 517 * wait here until all CPUs have finished the main action. 518 */ 519 atomic_add_int(&smp_rv_waiters[2], 1); 520 while (smp_rv_waiters[2] < smp_rv_ncpus) 521 cpu_spinwait(); 522 523 if (local_teardown_func != NULL) 524 local_teardown_func(local_func_arg); 525 } 526 527 /* 528 * Signal that the rendezvous is fully completed by this CPU. 529 * This means that no member of smp_rv_* pseudo-structure will be 530 * accessed by this target CPU after this point; in particular, 531 * memory pointed by smp_rv_func_arg. 532 * 533 * The release semantic ensures that all accesses performed by 534 * the current CPU are visible when smp_rendezvous_cpus() 535 * returns, by synchronizing with the 536 * atomic_load_acq_int(&smp_rv_waiters[3]). 537 */ 538 atomic_add_rel_int(&smp_rv_waiters[3], 1); 539 540 td->td_critnest--; 541 KASSERT(owepreempt == td->td_owepreempt, 542 ("rendezvous action changed td_owepreempt")); 543 } 544 545 void 546 smp_rendezvous_cpus(cpuset_t map, 547 void (* setup_func)(void *), 548 void (* action_func)(void *), 549 void (* teardown_func)(void *), 550 void *arg) 551 { 552 int curcpumap, i, ncpus = 0; 553 554 /* See comments in the !SMP case. */ 555 if (!smp_started) { 556 spinlock_enter(); 557 if (setup_func != NULL) 558 setup_func(arg); 559 if (action_func != NULL) 560 action_func(arg); 561 if (teardown_func != NULL) 562 teardown_func(arg); 563 spinlock_exit(); 564 return; 565 } 566 567 /* 568 * Make sure we come here with interrupts enabled. Otherwise we 569 * livelock if smp_ipi_mtx is owned by a thread which sent us an IPI. 570 */ 571 MPASS(curthread->td_md.md_spinlock_count == 0); 572 573 CPU_FOREACH(i) { 574 if (CPU_ISSET(i, &map)) 575 ncpus++; 576 } 577 if (ncpus == 0) 578 panic("ncpus is 0 with non-zero map"); 579 580 mtx_lock_spin(&smp_ipi_mtx); 581 582 /* Pass rendezvous parameters via global variables. */ 583 smp_rv_ncpus = ncpus; 584 smp_rv_setup_func = setup_func; 585 smp_rv_action_func = action_func; 586 smp_rv_teardown_func = teardown_func; 587 smp_rv_func_arg = arg; 588 smp_rv_waiters[1] = 0; 589 smp_rv_waiters[2] = 0; 590 smp_rv_waiters[3] = 0; 591 atomic_store_rel_int(&smp_rv_waiters[0], 0); 592 593 /* 594 * Signal other processors, which will enter the IPI with 595 * interrupts off. 596 */ 597 curcpumap = CPU_ISSET(curcpu, &map); 598 CPU_CLR(curcpu, &map); 599 ipi_selected(map, IPI_RENDEZVOUS); 600 601 /* Check if the current CPU is in the map */ 602 if (curcpumap != 0) 603 smp_rendezvous_action(); 604 605 /* 606 * Ensure that the master CPU waits for all the other 607 * CPUs to finish the rendezvous, so that smp_rv_* 608 * pseudo-structure and the arg are guaranteed to not 609 * be in use. 610 * 611 * Load acquire synchronizes with the release add in 612 * smp_rendezvous_action(), which ensures that our caller sees 613 * all memory actions done by the called functions on other 614 * CPUs. 615 */ 616 while (atomic_load_acq_int(&smp_rv_waiters[3]) < ncpus) 617 cpu_spinwait(); 618 619 mtx_unlock_spin(&smp_ipi_mtx); 620 } 621 622 void 623 smp_rendezvous(void (* setup_func)(void *), 624 void (* action_func)(void *), 625 void (* teardown_func)(void *), 626 void *arg) 627 { 628 smp_rendezvous_cpus(all_cpus, setup_func, action_func, teardown_func, arg); 629 } 630 631 static struct cpu_group group[MAXCPU * MAX_CACHE_LEVELS + 1]; 632 633 struct cpu_group * 634 smp_topo(void) 635 { 636 char cpusetbuf[CPUSETBUFSIZ], cpusetbuf2[CPUSETBUFSIZ]; 637 struct cpu_group *top; 638 639 /* 640 * Check for a fake topology request for debugging purposes. 641 */ 642 switch (smp_topology) { 643 case 1: 644 /* Dual core with no sharing. */ 645 top = smp_topo_1level(CG_SHARE_NONE, 2, 0); 646 break; 647 case 2: 648 /* No topology, all cpus are equal. */ 649 top = smp_topo_none(); 650 break; 651 case 3: 652 /* Dual core with shared L2. */ 653 top = smp_topo_1level(CG_SHARE_L2, 2, 0); 654 break; 655 case 4: 656 /* quad core, shared l3 among each package, private l2. */ 657 top = smp_topo_1level(CG_SHARE_L3, 4, 0); 658 break; 659 case 5: 660 /* quad core, 2 dualcore parts on each package share l2. */ 661 top = smp_topo_2level(CG_SHARE_NONE, 2, CG_SHARE_L2, 2, 0); 662 break; 663 case 6: 664 /* Single-core 2xHTT */ 665 top = smp_topo_1level(CG_SHARE_L1, 2, CG_FLAG_HTT); 666 break; 667 case 7: 668 /* quad core with a shared l3, 8 threads sharing L2. */ 669 top = smp_topo_2level(CG_SHARE_L3, 4, CG_SHARE_L2, 8, 670 CG_FLAG_SMT); 671 break; 672 default: 673 /* Default, ask the system what it wants. */ 674 top = cpu_topo(); 675 break; 676 } 677 /* 678 * Verify the returned topology. 679 */ 680 if (top->cg_count != mp_ncpus) 681 panic("Built bad topology at %p. CPU count %d != %d", 682 top, top->cg_count, mp_ncpus); 683 if (CPU_CMP(&top->cg_mask, &all_cpus)) 684 panic("Built bad topology at %p. CPU mask (%s) != (%s)", 685 top, cpusetobj_strprint(cpusetbuf, &top->cg_mask), 686 cpusetobj_strprint(cpusetbuf2, &all_cpus)); 687 688 /* 689 * Collapse nonsense levels that may be created out of convenience by 690 * the MD layers. They cause extra work in the search functions. 691 */ 692 while (top->cg_children == 1) { 693 top = &top->cg_child[0]; 694 top->cg_parent = NULL; 695 } 696 return (top); 697 } 698 699 struct cpu_group * 700 smp_topo_alloc(u_int count) 701 { 702 static u_int index; 703 u_int curr; 704 705 curr = index; 706 index += count; 707 return (&group[curr]); 708 } 709 710 struct cpu_group * 711 smp_topo_none(void) 712 { 713 struct cpu_group *top; 714 715 top = &group[0]; 716 top->cg_parent = NULL; 717 top->cg_child = NULL; 718 top->cg_mask = all_cpus; 719 top->cg_count = mp_ncpus; 720 top->cg_children = 0; 721 top->cg_level = CG_SHARE_NONE; 722 top->cg_flags = 0; 723 724 return (top); 725 } 726 727 static int 728 smp_topo_addleaf(struct cpu_group *parent, struct cpu_group *child, int share, 729 int count, int flags, int start) 730 { 731 char cpusetbuf[CPUSETBUFSIZ], cpusetbuf2[CPUSETBUFSIZ]; 732 cpuset_t mask; 733 int i; 734 735 CPU_ZERO(&mask); 736 for (i = 0; i < count; i++, start++) 737 CPU_SET(start, &mask); 738 child->cg_parent = parent; 739 child->cg_child = NULL; 740 child->cg_children = 0; 741 child->cg_level = share; 742 child->cg_count = count; 743 child->cg_flags = flags; 744 child->cg_mask = mask; 745 parent->cg_children++; 746 for (; parent != NULL; parent = parent->cg_parent) { 747 if (CPU_OVERLAP(&parent->cg_mask, &child->cg_mask)) 748 panic("Duplicate children in %p. mask (%s) child (%s)", 749 parent, 750 cpusetobj_strprint(cpusetbuf, &parent->cg_mask), 751 cpusetobj_strprint(cpusetbuf2, &child->cg_mask)); 752 CPU_OR(&parent->cg_mask, &child->cg_mask); 753 parent->cg_count += child->cg_count; 754 } 755 756 return (start); 757 } 758 759 struct cpu_group * 760 smp_topo_1level(int share, int count, int flags) 761 { 762 struct cpu_group *child; 763 struct cpu_group *top; 764 int packages; 765 int cpu; 766 int i; 767 768 cpu = 0; 769 top = &group[0]; 770 packages = mp_ncpus / count; 771 top->cg_child = child = &group[1]; 772 top->cg_level = CG_SHARE_NONE; 773 for (i = 0; i < packages; i++, child++) 774 cpu = smp_topo_addleaf(top, child, share, count, flags, cpu); 775 return (top); 776 } 777 778 struct cpu_group * 779 smp_topo_2level(int l2share, int l2count, int l1share, int l1count, 780 int l1flags) 781 { 782 struct cpu_group *top; 783 struct cpu_group *l1g; 784 struct cpu_group *l2g; 785 int cpu; 786 int i; 787 int j; 788 789 cpu = 0; 790 top = &group[0]; 791 l2g = &group[1]; 792 top->cg_child = l2g; 793 top->cg_level = CG_SHARE_NONE; 794 top->cg_children = mp_ncpus / (l2count * l1count); 795 l1g = l2g + top->cg_children; 796 for (i = 0; i < top->cg_children; i++, l2g++) { 797 l2g->cg_parent = top; 798 l2g->cg_child = l1g; 799 l2g->cg_level = l2share; 800 for (j = 0; j < l2count; j++, l1g++) 801 cpu = smp_topo_addleaf(l2g, l1g, l1share, l1count, 802 l1flags, cpu); 803 } 804 return (top); 805 } 806 807 struct cpu_group * 808 smp_topo_find(struct cpu_group *top, int cpu) 809 { 810 struct cpu_group *cg; 811 cpuset_t mask; 812 int children; 813 int i; 814 815 CPU_SETOF(cpu, &mask); 816 cg = top; 817 for (;;) { 818 if (!CPU_OVERLAP(&cg->cg_mask, &mask)) 819 return (NULL); 820 if (cg->cg_children == 0) 821 return (cg); 822 children = cg->cg_children; 823 for (i = 0, cg = cg->cg_child; i < children; cg++, i++) 824 if (CPU_OVERLAP(&cg->cg_mask, &mask)) 825 break; 826 } 827 return (NULL); 828 } 829 #else /* !SMP */ 830 831 void 832 smp_rendezvous_cpus(cpuset_t map, 833 void (*setup_func)(void *), 834 void (*action_func)(void *), 835 void (*teardown_func)(void *), 836 void *arg) 837 { 838 /* 839 * In the !SMP case we just need to ensure the same initial conditions 840 * as the SMP case. 841 */ 842 spinlock_enter(); 843 if (setup_func != NULL) 844 setup_func(arg); 845 if (action_func != NULL) 846 action_func(arg); 847 if (teardown_func != NULL) 848 teardown_func(arg); 849 spinlock_exit(); 850 } 851 852 void 853 smp_rendezvous(void (*setup_func)(void *), 854 void (*action_func)(void *), 855 void (*teardown_func)(void *), 856 void *arg) 857 { 858 859 smp_rendezvous_cpus(all_cpus, setup_func, action_func, teardown_func, 860 arg); 861 } 862 863 /* 864 * Provide dummy SMP support for UP kernels. Modules that need to use SMP 865 * APIs will still work using this dummy support. 866 */ 867 static void 868 mp_setvariables_for_up(void *dummy) 869 { 870 mp_ncpus = 1; 871 mp_ncores = 1; 872 mp_maxid = PCPU_GET(cpuid); 873 CPU_SETOF(mp_maxid, &all_cpus); 874 KASSERT(PCPU_GET(cpuid) == 0, ("UP must have a CPU ID of zero")); 875 } 876 SYSINIT(cpu_mp_setvariables, SI_SUB_TUNABLES, SI_ORDER_FIRST, 877 mp_setvariables_for_up, NULL); 878 #endif /* SMP */ 879 880 void 881 smp_no_rendezvous_barrier(void *dummy) 882 { 883 #ifdef SMP 884 KASSERT((!smp_started),("smp_no_rendezvous called and smp is started")); 885 #endif 886 } 887 888 void 889 smp_rendezvous_cpus_retry(cpuset_t map, 890 void (* setup_func)(void *), 891 void (* action_func)(void *), 892 void (* teardown_func)(void *), 893 void (* wait_func)(void *, int), 894 struct smp_rendezvous_cpus_retry_arg *arg) 895 { 896 int cpu; 897 898 /* 899 * Execute an action on all specified CPUs while retrying until they 900 * all acknowledge completion. 901 */ 902 CPU_COPY(&map, &arg->cpus); 903 for (;;) { 904 smp_rendezvous_cpus( 905 arg->cpus, 906 setup_func, 907 action_func, 908 teardown_func, 909 arg); 910 911 if (CPU_EMPTY(&arg->cpus)) 912 break; 913 914 CPU_FOREACH(cpu) { 915 if (!CPU_ISSET(cpu, &arg->cpus)) 916 continue; 917 wait_func(arg, cpu); 918 } 919 } 920 } 921 922 void 923 smp_rendezvous_cpus_done(struct smp_rendezvous_cpus_retry_arg *arg) 924 { 925 926 CPU_CLR_ATOMIC(curcpu, &arg->cpus); 927 } 928 929 /* 930 * Wait for specified idle threads to switch once. This ensures that even 931 * preempted threads have cycled through the switch function once, 932 * exiting their codepaths. This allows us to change global pointers 933 * with no other synchronization. 934 */ 935 int 936 quiesce_cpus(cpuset_t map, const char *wmesg, int prio) 937 { 938 struct pcpu *pcpu; 939 u_int gen[MAXCPU]; 940 int error; 941 int cpu; 942 943 error = 0; 944 for (cpu = 0; cpu <= mp_maxid; cpu++) { 945 if (!CPU_ISSET(cpu, &map) || CPU_ABSENT(cpu)) 946 continue; 947 pcpu = pcpu_find(cpu); 948 gen[cpu] = pcpu->pc_idlethread->td_generation; 949 } 950 for (cpu = 0; cpu <= mp_maxid; cpu++) { 951 if (!CPU_ISSET(cpu, &map) || CPU_ABSENT(cpu)) 952 continue; 953 pcpu = pcpu_find(cpu); 954 thread_lock(curthread); 955 sched_bind(curthread, cpu); 956 thread_unlock(curthread); 957 while (gen[cpu] == pcpu->pc_idlethread->td_generation) { 958 error = tsleep(quiesce_cpus, prio, wmesg, 1); 959 if (error != EWOULDBLOCK) 960 goto out; 961 error = 0; 962 } 963 } 964 out: 965 thread_lock(curthread); 966 sched_unbind(curthread); 967 thread_unlock(curthread); 968 969 return (error); 970 } 971 972 int 973 quiesce_all_cpus(const char *wmesg, int prio) 974 { 975 976 return quiesce_cpus(all_cpus, wmesg, prio); 977 } 978 979 /* 980 * Observe all CPUs not executing in critical section. 981 * We are not in one so the check for us is safe. If the found 982 * thread changes to something else we know the section was 983 * exited as well. 984 */ 985 void 986 quiesce_all_critical(void) 987 { 988 struct thread *td, *newtd; 989 struct pcpu *pcpu; 990 int cpu; 991 992 MPASS(curthread->td_critnest == 0); 993 994 CPU_FOREACH(cpu) { 995 pcpu = cpuid_to_pcpu[cpu]; 996 td = pcpu->pc_curthread; 997 for (;;) { 998 if (td->td_critnest == 0) 999 break; 1000 cpu_spinwait(); 1001 newtd = (struct thread *) 1002 atomic_load_acq_ptr((void *)pcpu->pc_curthread); 1003 if (td != newtd) 1004 break; 1005 } 1006 } 1007 } 1008 1009 static void 1010 cpus_fence_seq_cst_issue(void *arg __unused) 1011 { 1012 1013 atomic_thread_fence_seq_cst(); 1014 } 1015 1016 /* 1017 * Send an IPI forcing a sequentially consistent fence. 1018 * 1019 * Allows replacement of an explicitly fence with a compiler barrier. 1020 * Trades speed up during normal execution for a significant slowdown when 1021 * the barrier is needed. 1022 */ 1023 void 1024 cpus_fence_seq_cst(void) 1025 { 1026 1027 #ifdef SMP 1028 smp_rendezvous( 1029 smp_no_rendezvous_barrier, 1030 cpus_fence_seq_cst_issue, 1031 smp_no_rendezvous_barrier, 1032 NULL 1033 ); 1034 #else 1035 cpus_fence_seq_cst_issue(NULL); 1036 #endif 1037 } 1038 1039 /* Extra care is taken with this sysctl because the data type is volatile */ 1040 static int 1041 sysctl_kern_smp_active(SYSCTL_HANDLER_ARGS) 1042 { 1043 int error, active; 1044 1045 active = smp_started; 1046 error = SYSCTL_OUT(req, &active, sizeof(active)); 1047 return (error); 1048 } 1049 1050 #ifdef SMP 1051 void 1052 topo_init_node(struct topo_node *node) 1053 { 1054 1055 bzero(node, sizeof(*node)); 1056 TAILQ_INIT(&node->children); 1057 } 1058 1059 void 1060 topo_init_root(struct topo_node *root) 1061 { 1062 1063 topo_init_node(root); 1064 root->type = TOPO_TYPE_SYSTEM; 1065 } 1066 1067 /* 1068 * Add a child node with the given ID under the given parent. 1069 * Do nothing if there is already a child with that ID. 1070 */ 1071 struct topo_node * 1072 topo_add_node_by_hwid(struct topo_node *parent, int hwid, 1073 topo_node_type type, uintptr_t subtype) 1074 { 1075 struct topo_node *node; 1076 1077 TAILQ_FOREACH_REVERSE(node, &parent->children, 1078 topo_children, siblings) { 1079 if (node->hwid == hwid 1080 && node->type == type && node->subtype == subtype) { 1081 return (node); 1082 } 1083 } 1084 1085 node = malloc(sizeof(*node), M_TOPO, M_WAITOK); 1086 topo_init_node(node); 1087 node->parent = parent; 1088 node->hwid = hwid; 1089 node->type = type; 1090 node->subtype = subtype; 1091 TAILQ_INSERT_TAIL(&parent->children, node, siblings); 1092 parent->nchildren++; 1093 1094 return (node); 1095 } 1096 1097 /* 1098 * Find a child node with the given ID under the given parent. 1099 */ 1100 struct topo_node * 1101 topo_find_node_by_hwid(struct topo_node *parent, int hwid, 1102 topo_node_type type, uintptr_t subtype) 1103 { 1104 1105 struct topo_node *node; 1106 1107 TAILQ_FOREACH(node, &parent->children, siblings) { 1108 if (node->hwid == hwid 1109 && node->type == type && node->subtype == subtype) { 1110 return (node); 1111 } 1112 } 1113 1114 return (NULL); 1115 } 1116 1117 /* 1118 * Given a node change the order of its parent's child nodes such 1119 * that the node becomes the firt child while preserving the cyclic 1120 * order of the children. In other words, the given node is promoted 1121 * by rotation. 1122 */ 1123 void 1124 topo_promote_child(struct topo_node *child) 1125 { 1126 struct topo_node *next; 1127 struct topo_node *node; 1128 struct topo_node *parent; 1129 1130 parent = child->parent; 1131 next = TAILQ_NEXT(child, siblings); 1132 TAILQ_REMOVE(&parent->children, child, siblings); 1133 TAILQ_INSERT_HEAD(&parent->children, child, siblings); 1134 1135 while (next != NULL) { 1136 node = next; 1137 next = TAILQ_NEXT(node, siblings); 1138 TAILQ_REMOVE(&parent->children, node, siblings); 1139 TAILQ_INSERT_AFTER(&parent->children, child, node, siblings); 1140 child = node; 1141 } 1142 } 1143 1144 /* 1145 * Iterate to the next node in the depth-first search (traversal) of 1146 * the topology tree. 1147 */ 1148 struct topo_node * 1149 topo_next_node(struct topo_node *top, struct topo_node *node) 1150 { 1151 struct topo_node *next; 1152 1153 if ((next = TAILQ_FIRST(&node->children)) != NULL) 1154 return (next); 1155 1156 if ((next = TAILQ_NEXT(node, siblings)) != NULL) 1157 return (next); 1158 1159 while (node != top && (node = node->parent) != top) 1160 if ((next = TAILQ_NEXT(node, siblings)) != NULL) 1161 return (next); 1162 1163 return (NULL); 1164 } 1165 1166 /* 1167 * Iterate to the next node in the depth-first search of the topology tree, 1168 * but without descending below the current node. 1169 */ 1170 struct topo_node * 1171 topo_next_nonchild_node(struct topo_node *top, struct topo_node *node) 1172 { 1173 struct topo_node *next; 1174 1175 if ((next = TAILQ_NEXT(node, siblings)) != NULL) 1176 return (next); 1177 1178 while (node != top && (node = node->parent) != top) 1179 if ((next = TAILQ_NEXT(node, siblings)) != NULL) 1180 return (next); 1181 1182 return (NULL); 1183 } 1184 1185 /* 1186 * Assign the given ID to the given topology node that represents a logical 1187 * processor. 1188 */ 1189 void 1190 topo_set_pu_id(struct topo_node *node, cpuid_t id) 1191 { 1192 1193 KASSERT(node->type == TOPO_TYPE_PU, 1194 ("topo_set_pu_id: wrong node type: %u", node->type)); 1195 KASSERT(CPU_EMPTY(&node->cpuset) && node->cpu_count == 0, 1196 ("topo_set_pu_id: cpuset already not empty")); 1197 node->id = id; 1198 CPU_SET(id, &node->cpuset); 1199 node->cpu_count = 1; 1200 node->subtype = 1; 1201 1202 while ((node = node->parent) != NULL) { 1203 KASSERT(!CPU_ISSET(id, &node->cpuset), 1204 ("logical ID %u is already set in node %p", id, node)); 1205 CPU_SET(id, &node->cpuset); 1206 node->cpu_count++; 1207 } 1208 } 1209 1210 static struct topology_spec { 1211 topo_node_type type; 1212 bool match_subtype; 1213 uintptr_t subtype; 1214 } topology_level_table[TOPO_LEVEL_COUNT] = { 1215 [TOPO_LEVEL_PKG] = { .type = TOPO_TYPE_PKG, }, 1216 [TOPO_LEVEL_GROUP] = { .type = TOPO_TYPE_GROUP, }, 1217 [TOPO_LEVEL_CACHEGROUP] = { 1218 .type = TOPO_TYPE_CACHE, 1219 .match_subtype = true, 1220 .subtype = CG_SHARE_L3, 1221 }, 1222 [TOPO_LEVEL_CORE] = { .type = TOPO_TYPE_CORE, }, 1223 [TOPO_LEVEL_THREAD] = { .type = TOPO_TYPE_PU, }, 1224 }; 1225 1226 static bool 1227 topo_analyze_table(struct topo_node *root, int all, enum topo_level level, 1228 struct topo_analysis *results) 1229 { 1230 struct topology_spec *spec; 1231 struct topo_node *node; 1232 int count; 1233 1234 if (level >= TOPO_LEVEL_COUNT) 1235 return (true); 1236 1237 spec = &topology_level_table[level]; 1238 count = 0; 1239 node = topo_next_node(root, root); 1240 1241 while (node != NULL) { 1242 if (node->type != spec->type || 1243 (spec->match_subtype && node->subtype != spec->subtype)) { 1244 node = topo_next_node(root, node); 1245 continue; 1246 } 1247 if (!all && CPU_EMPTY(&node->cpuset)) { 1248 node = topo_next_nonchild_node(root, node); 1249 continue; 1250 } 1251 1252 count++; 1253 1254 if (!topo_analyze_table(node, all, level + 1, results)) 1255 return (false); 1256 1257 node = topo_next_nonchild_node(root, node); 1258 } 1259 1260 /* No explicit subgroups is essentially one subgroup. */ 1261 if (count == 0) { 1262 count = 1; 1263 1264 if (!topo_analyze_table(root, all, level + 1, results)) 1265 return (false); 1266 } 1267 1268 if (results->entities[level] == -1) 1269 results->entities[level] = count; 1270 else if (results->entities[level] != count) 1271 return (false); 1272 1273 return (true); 1274 } 1275 1276 /* 1277 * Check if the topology is uniform, that is, each package has the same number 1278 * of cores in it and each core has the same number of threads (logical 1279 * processors) in it. If so, calculate the number of packages, the number of 1280 * groups per package, the number of cachegroups per group, and the number of 1281 * logical processors per cachegroup. 'all' parameter tells whether to include 1282 * administratively disabled logical processors into the analysis. 1283 */ 1284 int 1285 topo_analyze(struct topo_node *topo_root, int all, 1286 struct topo_analysis *results) 1287 { 1288 1289 results->entities[TOPO_LEVEL_PKG] = -1; 1290 results->entities[TOPO_LEVEL_CORE] = -1; 1291 results->entities[TOPO_LEVEL_THREAD] = -1; 1292 results->entities[TOPO_LEVEL_GROUP] = -1; 1293 results->entities[TOPO_LEVEL_CACHEGROUP] = -1; 1294 1295 if (!topo_analyze_table(topo_root, all, TOPO_LEVEL_PKG, results)) 1296 return (0); 1297 1298 KASSERT(results->entities[TOPO_LEVEL_PKG] > 0, 1299 ("bug in topology or analysis")); 1300 1301 return (1); 1302 } 1303 1304 #endif /* SMP */ 1305