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 cpusetsizemin = howmany(mp_maxid + 1, NBBY); 153 } 154 SYSINIT(cpu_mp_setmaxid, SI_SUB_TUNABLES, SI_ORDER_FIRST, mp_setmaxid, NULL); 155 156 /* 157 * Call the MD SMP initialization code. 158 */ 159 static void 160 mp_start(void *dummy) 161 { 162 163 mtx_init(&smp_ipi_mtx, "smp rendezvous", NULL, MTX_SPIN); 164 165 /* Probe for MP hardware. */ 166 if (smp_disabled != 0 || cpu_mp_probe() == 0) { 167 mp_ncores = 1; 168 mp_ncpus = 1; 169 CPU_SETOF(PCPU_GET(cpuid), &all_cpus); 170 return; 171 } 172 173 cpu_mp_start(); 174 printf("FreeBSD/SMP: Multiprocessor System Detected: %d CPUs\n", 175 mp_ncpus); 176 177 /* Provide a default for most architectures that don't have SMT/HTT. */ 178 if (mp_ncores < 0) 179 mp_ncores = mp_ncpus; 180 181 cpu_mp_announce(); 182 } 183 SYSINIT(cpu_mp, SI_SUB_CPU, SI_ORDER_THIRD, mp_start, NULL); 184 185 void 186 forward_signal(struct thread *td) 187 { 188 int id; 189 190 /* 191 * signotify() has already set TDA_AST and TDA_SIG on td_ast for 192 * this thread, so all we need to do is poke it if it is currently 193 * executing so that it executes ast(). 194 */ 195 THREAD_LOCK_ASSERT(td, MA_OWNED); 196 KASSERT(TD_IS_RUNNING(td), 197 ("forward_signal: thread is not TDS_RUNNING")); 198 199 CTR1(KTR_SMP, "forward_signal(%p)", td->td_proc); 200 201 if (!smp_started || cold || KERNEL_PANICKED()) 202 return; 203 if (!forward_signal_enabled) 204 return; 205 206 /* No need to IPI ourself. */ 207 if (td == curthread) 208 return; 209 210 id = td->td_oncpu; 211 if (id == NOCPU) 212 return; 213 ipi_cpu(id, IPI_AST); 214 } 215 216 /* 217 * When called the executing CPU will send an IPI to all other CPUs 218 * requesting that they halt execution. 219 * 220 * Usually (but not necessarily) called with 'other_cpus' as its arg. 221 * 222 * - Signals all CPUs in map to stop. 223 * - Waits for each to stop. 224 * 225 * Returns: 226 * -1: error 227 * 0: NA 228 * 1: ok 229 * 230 */ 231 #if defined(__amd64__) || defined(__i386__) 232 #define X86 1 233 #else 234 #define X86 0 235 #endif 236 static int 237 generic_stop_cpus(cpuset_t map, u_int type) 238 { 239 #ifdef KTR 240 char cpusetbuf[CPUSETBUFSIZ]; 241 #endif 242 static volatile u_int stopping_cpu = NOCPU; 243 int i; 244 volatile cpuset_t *cpus; 245 246 KASSERT( 247 type == IPI_STOP || type == IPI_STOP_HARD 248 #if X86 249 || type == IPI_SUSPEND 250 #endif 251 , ("%s: invalid stop type", __func__)); 252 253 if (!smp_started) 254 return (0); 255 256 CTR2(KTR_SMP, "stop_cpus(%s) with %u type", 257 cpusetobj_strprint(cpusetbuf, &map), type); 258 259 #if X86 260 /* 261 * When suspending, ensure there are are no IPIs in progress. 262 * IPIs that have been issued, but not yet delivered (e.g. 263 * not pending on a vCPU when running under virtualization) 264 * will be lost, violating FreeBSD's assumption of reliable 265 * IPI delivery. 266 */ 267 if (type == IPI_SUSPEND) 268 mtx_lock_spin(&smp_ipi_mtx); 269 #endif 270 271 #if X86 272 if (!nmi_is_broadcast || nmi_kdb_lock == 0) { 273 #endif 274 if (stopping_cpu != PCPU_GET(cpuid)) 275 while (atomic_cmpset_int(&stopping_cpu, NOCPU, 276 PCPU_GET(cpuid)) == 0) 277 while (stopping_cpu != NOCPU) 278 cpu_spinwait(); /* spin */ 279 280 /* send the stop IPI to all CPUs in map */ 281 ipi_selected(map, type); 282 #if X86 283 } 284 #endif 285 286 #if X86 287 if (type == IPI_SUSPEND) 288 cpus = &suspended_cpus; 289 else 290 #endif 291 cpus = &stopped_cpus; 292 293 i = 0; 294 while (!CPU_SUBSET(cpus, &map)) { 295 /* spin */ 296 cpu_spinwait(); 297 i++; 298 if (i == 100000000) { 299 printf("timeout stopping cpus\n"); 300 break; 301 } 302 } 303 304 #if X86 305 if (type == IPI_SUSPEND) 306 mtx_unlock_spin(&smp_ipi_mtx); 307 #endif 308 309 stopping_cpu = NOCPU; 310 return (1); 311 } 312 313 int 314 stop_cpus(cpuset_t map) 315 { 316 317 return (generic_stop_cpus(map, IPI_STOP)); 318 } 319 320 int 321 stop_cpus_hard(cpuset_t map) 322 { 323 324 return (generic_stop_cpus(map, IPI_STOP_HARD)); 325 } 326 327 #if X86 328 int 329 suspend_cpus(cpuset_t map) 330 { 331 332 return (generic_stop_cpus(map, IPI_SUSPEND)); 333 } 334 #endif 335 336 /* 337 * Called by a CPU to restart stopped CPUs. 338 * 339 * Usually (but not necessarily) called with 'stopped_cpus' as its arg. 340 * 341 * - Signals all CPUs in map to restart. 342 * - Waits for each to restart. 343 * 344 * Returns: 345 * -1: error 346 * 0: NA 347 * 1: ok 348 */ 349 static int 350 generic_restart_cpus(cpuset_t map, u_int type) 351 { 352 #ifdef KTR 353 char cpusetbuf[CPUSETBUFSIZ]; 354 #endif 355 volatile cpuset_t *cpus; 356 357 #if X86 358 KASSERT(type == IPI_STOP || type == IPI_STOP_HARD 359 || type == IPI_SUSPEND, ("%s: invalid stop type", __func__)); 360 361 if (!smp_started) 362 return (0); 363 364 CTR1(KTR_SMP, "restart_cpus(%s)", cpusetobj_strprint(cpusetbuf, &map)); 365 366 if (type == IPI_SUSPEND) 367 cpus = &resuming_cpus; 368 else 369 cpus = &stopped_cpus; 370 371 /* signal other cpus to restart */ 372 if (type == IPI_SUSPEND) 373 CPU_COPY_STORE_REL(&map, &toresume_cpus); 374 else 375 CPU_COPY_STORE_REL(&map, &started_cpus); 376 377 /* 378 * Wake up any CPUs stopped with MWAIT. From MI code we can't tell if 379 * MONITOR/MWAIT is enabled, but the potentially redundant writes are 380 * relatively inexpensive. 381 */ 382 if (type == IPI_STOP) { 383 struct monitorbuf *mb; 384 u_int id; 385 386 CPU_FOREACH(id) { 387 if (!CPU_ISSET(id, &map)) 388 continue; 389 390 mb = &pcpu_find(id)->pc_monitorbuf; 391 atomic_store_int(&mb->stop_state, 392 MONITOR_STOPSTATE_RUNNING); 393 } 394 } 395 396 if (!nmi_is_broadcast || nmi_kdb_lock == 0) { 397 /* wait for each to clear its bit */ 398 while (CPU_OVERLAP(cpus, &map)) 399 cpu_spinwait(); 400 } 401 #else /* !X86 */ 402 KASSERT(type == IPI_STOP || type == IPI_STOP_HARD, 403 ("%s: invalid stop type", __func__)); 404 405 if (!smp_started) 406 return (0); 407 408 CTR1(KTR_SMP, "restart_cpus(%s)", cpusetobj_strprint(cpusetbuf, &map)); 409 410 cpus = &stopped_cpus; 411 412 /* signal other cpus to restart */ 413 CPU_COPY_STORE_REL(&map, &started_cpus); 414 415 /* wait for each to clear its bit */ 416 while (CPU_OVERLAP(cpus, &map)) 417 cpu_spinwait(); 418 #endif 419 return (1); 420 } 421 422 int 423 restart_cpus(cpuset_t map) 424 { 425 426 return (generic_restart_cpus(map, IPI_STOP)); 427 } 428 429 #if X86 430 int 431 resume_cpus(cpuset_t map) 432 { 433 434 return (generic_restart_cpus(map, IPI_SUSPEND)); 435 } 436 #endif 437 #undef X86 438 439 /* 440 * All-CPU rendezvous. CPUs are signalled, all execute the setup function 441 * (if specified), rendezvous, execute the action function (if specified), 442 * rendezvous again, execute the teardown function (if specified), and then 443 * resume. 444 * 445 * Note that the supplied external functions _must_ be reentrant and aware 446 * that they are running in parallel and in an unknown lock context. 447 */ 448 void 449 smp_rendezvous_action(void) 450 { 451 struct thread *td; 452 void *local_func_arg; 453 void (*local_setup_func)(void*); 454 void (*local_action_func)(void*); 455 void (*local_teardown_func)(void*); 456 #ifdef INVARIANTS 457 int owepreempt; 458 #endif 459 460 /* Ensure we have up-to-date values. */ 461 atomic_add_acq_int(&smp_rv_waiters[0], 1); 462 while (smp_rv_waiters[0] < smp_rv_ncpus) 463 cpu_spinwait(); 464 465 /* Fetch rendezvous parameters after acquire barrier. */ 466 local_func_arg = smp_rv_func_arg; 467 local_setup_func = smp_rv_setup_func; 468 local_action_func = smp_rv_action_func; 469 local_teardown_func = smp_rv_teardown_func; 470 471 /* 472 * Use a nested critical section to prevent any preemptions 473 * from occurring during a rendezvous action routine. 474 * Specifically, if a rendezvous handler is invoked via an IPI 475 * and the interrupted thread was in the critical_exit() 476 * function after setting td_critnest to 0 but before 477 * performing a deferred preemption, this routine can be 478 * invoked with td_critnest set to 0 and td_owepreempt true. 479 * In that case, a critical_exit() during the rendezvous 480 * action would trigger a preemption which is not permitted in 481 * a rendezvous action. To fix this, wrap all of the 482 * rendezvous action handlers in a critical section. We 483 * cannot use a regular critical section however as having 484 * critical_exit() preempt from this routine would also be 485 * problematic (the preemption must not occur before the IPI 486 * has been acknowledged via an EOI). Instead, we 487 * intentionally ignore td_owepreempt when leaving the 488 * critical section. This should be harmless because we do 489 * not permit rendezvous action routines to schedule threads, 490 * and thus td_owepreempt should never transition from 0 to 1 491 * during this routine. 492 */ 493 td = curthread; 494 td->td_critnest++; 495 #ifdef INVARIANTS 496 owepreempt = td->td_owepreempt; 497 #endif 498 499 /* 500 * If requested, run a setup function before the main action 501 * function. Ensure all CPUs have completed the setup 502 * function before moving on to the action function. 503 */ 504 if (local_setup_func != smp_no_rendezvous_barrier) { 505 if (local_setup_func != NULL) 506 local_setup_func(local_func_arg); 507 atomic_add_int(&smp_rv_waiters[1], 1); 508 while (smp_rv_waiters[1] < smp_rv_ncpus) 509 cpu_spinwait(); 510 } 511 512 if (local_action_func != NULL) 513 local_action_func(local_func_arg); 514 515 if (local_teardown_func != smp_no_rendezvous_barrier) { 516 /* 517 * Signal that the main action has been completed. If a 518 * full exit rendezvous is requested, then all CPUs will 519 * wait here until all CPUs have finished the main action. 520 */ 521 atomic_add_int(&smp_rv_waiters[2], 1); 522 while (smp_rv_waiters[2] < smp_rv_ncpus) 523 cpu_spinwait(); 524 525 if (local_teardown_func != NULL) 526 local_teardown_func(local_func_arg); 527 } 528 529 /* 530 * Signal that the rendezvous is fully completed by this CPU. 531 * This means that no member of smp_rv_* pseudo-structure will be 532 * accessed by this target CPU after this point; in particular, 533 * memory pointed by smp_rv_func_arg. 534 * 535 * The release semantic ensures that all accesses performed by 536 * the current CPU are visible when smp_rendezvous_cpus() 537 * returns, by synchronizing with the 538 * atomic_load_acq_int(&smp_rv_waiters[3]). 539 */ 540 atomic_add_rel_int(&smp_rv_waiters[3], 1); 541 542 td->td_critnest--; 543 KASSERT(owepreempt == td->td_owepreempt, 544 ("rendezvous action changed td_owepreempt")); 545 } 546 547 void 548 smp_rendezvous_cpus(cpuset_t map, 549 void (* setup_func)(void *), 550 void (* action_func)(void *), 551 void (* teardown_func)(void *), 552 void *arg) 553 { 554 int curcpumap, i, ncpus = 0; 555 556 /* See comments in the !SMP case. */ 557 if (!smp_started) { 558 spinlock_enter(); 559 if (setup_func != NULL) 560 setup_func(arg); 561 if (action_func != NULL) 562 action_func(arg); 563 if (teardown_func != NULL) 564 teardown_func(arg); 565 spinlock_exit(); 566 return; 567 } 568 569 /* 570 * Make sure we come here with interrupts enabled. Otherwise we 571 * livelock if smp_ipi_mtx is owned by a thread which sent us an IPI. 572 */ 573 MPASS(curthread->td_md.md_spinlock_count == 0); 574 575 CPU_FOREACH(i) { 576 if (CPU_ISSET(i, &map)) 577 ncpus++; 578 } 579 if (ncpus == 0) 580 panic("ncpus is 0 with non-zero map"); 581 582 mtx_lock_spin(&smp_ipi_mtx); 583 584 /* Pass rendezvous parameters via global variables. */ 585 smp_rv_ncpus = ncpus; 586 smp_rv_setup_func = setup_func; 587 smp_rv_action_func = action_func; 588 smp_rv_teardown_func = teardown_func; 589 smp_rv_func_arg = arg; 590 smp_rv_waiters[1] = 0; 591 smp_rv_waiters[2] = 0; 592 smp_rv_waiters[3] = 0; 593 atomic_store_rel_int(&smp_rv_waiters[0], 0); 594 595 /* 596 * Signal other processors, which will enter the IPI with 597 * interrupts off. 598 */ 599 curcpumap = CPU_ISSET(curcpu, &map); 600 CPU_CLR(curcpu, &map); 601 ipi_selected(map, IPI_RENDEZVOUS); 602 603 /* Check if the current CPU is in the map */ 604 if (curcpumap != 0) 605 smp_rendezvous_action(); 606 607 /* 608 * Ensure that the master CPU waits for all the other 609 * CPUs to finish the rendezvous, so that smp_rv_* 610 * pseudo-structure and the arg are guaranteed to not 611 * be in use. 612 * 613 * Load acquire synchronizes with the release add in 614 * smp_rendezvous_action(), which ensures that our caller sees 615 * all memory actions done by the called functions on other 616 * CPUs. 617 */ 618 while (atomic_load_acq_int(&smp_rv_waiters[3]) < ncpus) 619 cpu_spinwait(); 620 621 mtx_unlock_spin(&smp_ipi_mtx); 622 } 623 624 void 625 smp_rendezvous(void (* setup_func)(void *), 626 void (* action_func)(void *), 627 void (* teardown_func)(void *), 628 void *arg) 629 { 630 smp_rendezvous_cpus(all_cpus, setup_func, action_func, teardown_func, arg); 631 } 632 633 static void 634 smp_topo_fill(struct cpu_group *cg) 635 { 636 int c; 637 638 for (c = 0; c < cg->cg_children; c++) 639 smp_topo_fill(&cg->cg_child[c]); 640 cg->cg_first = CPU_FFS(&cg->cg_mask) - 1; 641 cg->cg_last = CPU_FLS(&cg->cg_mask) - 1; 642 } 643 644 struct cpu_group * 645 smp_topo(void) 646 { 647 char cpusetbuf[CPUSETBUFSIZ], cpusetbuf2[CPUSETBUFSIZ]; 648 static struct cpu_group *top = NULL; 649 650 /* 651 * The first call to smp_topo() is guaranteed to occur 652 * during the kernel boot while we are still single-threaded. 653 */ 654 if (top != NULL) 655 return (top); 656 657 /* 658 * Check for a fake topology request for debugging purposes. 659 */ 660 switch (smp_topology) { 661 case 1: 662 /* Dual core with no sharing. */ 663 top = smp_topo_1level(CG_SHARE_NONE, 2, 0); 664 break; 665 case 2: 666 /* No topology, all cpus are equal. */ 667 top = smp_topo_none(); 668 break; 669 case 3: 670 /* Dual core with shared L2. */ 671 top = smp_topo_1level(CG_SHARE_L2, 2, 0); 672 break; 673 case 4: 674 /* quad core, shared l3 among each package, private l2. */ 675 top = smp_topo_1level(CG_SHARE_L3, 4, 0); 676 break; 677 case 5: 678 /* quad core, 2 dualcore parts on each package share l2. */ 679 top = smp_topo_2level(CG_SHARE_NONE, 2, CG_SHARE_L2, 2, 0); 680 break; 681 case 6: 682 /* Single-core 2xHTT */ 683 top = smp_topo_1level(CG_SHARE_L1, 2, CG_FLAG_HTT); 684 break; 685 case 7: 686 /* quad core with a shared l3, 8 threads sharing L2. */ 687 top = smp_topo_2level(CG_SHARE_L3, 4, CG_SHARE_L2, 8, 688 CG_FLAG_SMT); 689 break; 690 default: 691 /* Default, ask the system what it wants. */ 692 top = cpu_topo(); 693 break; 694 } 695 /* 696 * Verify the returned topology. 697 */ 698 if (top->cg_count != mp_ncpus) 699 panic("Built bad topology at %p. CPU count %d != %d", 700 top, top->cg_count, mp_ncpus); 701 if (CPU_CMP(&top->cg_mask, &all_cpus)) 702 panic("Built bad topology at %p. CPU mask (%s) != (%s)", 703 top, cpusetobj_strprint(cpusetbuf, &top->cg_mask), 704 cpusetobj_strprint(cpusetbuf2, &all_cpus)); 705 706 /* 707 * Collapse nonsense levels that may be created out of convenience by 708 * the MD layers. They cause extra work in the search functions. 709 */ 710 while (top->cg_children == 1) { 711 top = &top->cg_child[0]; 712 top->cg_parent = NULL; 713 } 714 smp_topo_fill(top); 715 return (top); 716 } 717 718 struct cpu_group * 719 smp_topo_alloc(u_int count) 720 { 721 static struct cpu_group *group = NULL; 722 static u_int index; 723 u_int curr; 724 725 if (group == NULL) { 726 group = mallocarray((mp_maxid + 1) * MAX_CACHE_LEVELS + 1, 727 sizeof(*group), M_DEVBUF, M_WAITOK | M_ZERO); 728 } 729 curr = index; 730 index += count; 731 return (&group[curr]); 732 } 733 734 struct cpu_group * 735 smp_topo_none(void) 736 { 737 struct cpu_group *top; 738 739 top = smp_topo_alloc(1); 740 top->cg_parent = NULL; 741 top->cg_child = NULL; 742 top->cg_mask = all_cpus; 743 top->cg_count = mp_ncpus; 744 top->cg_children = 0; 745 top->cg_level = CG_SHARE_NONE; 746 top->cg_flags = 0; 747 748 return (top); 749 } 750 751 static int 752 smp_topo_addleaf(struct cpu_group *parent, struct cpu_group *child, int share, 753 int count, int flags, int start) 754 { 755 char cpusetbuf[CPUSETBUFSIZ], cpusetbuf2[CPUSETBUFSIZ]; 756 cpuset_t mask; 757 int i; 758 759 CPU_ZERO(&mask); 760 for (i = 0; i < count; i++, start++) 761 CPU_SET(start, &mask); 762 child->cg_parent = parent; 763 child->cg_child = NULL; 764 child->cg_children = 0; 765 child->cg_level = share; 766 child->cg_count = count; 767 child->cg_flags = flags; 768 child->cg_mask = mask; 769 parent->cg_children++; 770 for (; parent != NULL; parent = parent->cg_parent) { 771 if (CPU_OVERLAP(&parent->cg_mask, &child->cg_mask)) 772 panic("Duplicate children in %p. mask (%s) child (%s)", 773 parent, 774 cpusetobj_strprint(cpusetbuf, &parent->cg_mask), 775 cpusetobj_strprint(cpusetbuf2, &child->cg_mask)); 776 CPU_OR(&parent->cg_mask, &parent->cg_mask, &child->cg_mask); 777 parent->cg_count += child->cg_count; 778 } 779 780 return (start); 781 } 782 783 struct cpu_group * 784 smp_topo_1level(int share, int count, int flags) 785 { 786 struct cpu_group *child; 787 struct cpu_group *top; 788 int packages; 789 int cpu; 790 int i; 791 792 cpu = 0; 793 packages = mp_ncpus / count; 794 top = smp_topo_alloc(1 + packages); 795 top->cg_child = child = top + 1; 796 top->cg_level = CG_SHARE_NONE; 797 for (i = 0; i < packages; i++, child++) 798 cpu = smp_topo_addleaf(top, child, share, count, flags, cpu); 799 return (top); 800 } 801 802 struct cpu_group * 803 smp_topo_2level(int l2share, int l2count, int l1share, int l1count, 804 int l1flags) 805 { 806 struct cpu_group *top; 807 struct cpu_group *l1g; 808 struct cpu_group *l2g; 809 int cpu; 810 int i; 811 int j; 812 813 cpu = 0; 814 top = smp_topo_alloc(1 + mp_ncpus / (l2count * l1count) + 815 mp_ncpus / l1count); 816 l2g = top + 1; 817 top->cg_child = l2g; 818 top->cg_level = CG_SHARE_NONE; 819 top->cg_children = mp_ncpus / (l2count * l1count); 820 l1g = l2g + top->cg_children; 821 for (i = 0; i < top->cg_children; i++, l2g++) { 822 l2g->cg_parent = top; 823 l2g->cg_child = l1g; 824 l2g->cg_level = l2share; 825 for (j = 0; j < l2count; j++, l1g++) 826 cpu = smp_topo_addleaf(l2g, l1g, l1share, l1count, 827 l1flags, cpu); 828 } 829 return (top); 830 } 831 832 struct cpu_group * 833 smp_topo_find(struct cpu_group *top, int cpu) 834 { 835 struct cpu_group *cg; 836 cpuset_t mask; 837 int children; 838 int i; 839 840 CPU_SETOF(cpu, &mask); 841 cg = top; 842 for (;;) { 843 if (!CPU_OVERLAP(&cg->cg_mask, &mask)) 844 return (NULL); 845 if (cg->cg_children == 0) 846 return (cg); 847 children = cg->cg_children; 848 for (i = 0, cg = cg->cg_child; i < children; cg++, i++) 849 if (CPU_OVERLAP(&cg->cg_mask, &mask)) 850 break; 851 } 852 return (NULL); 853 } 854 #else /* !SMP */ 855 856 void 857 smp_rendezvous_cpus(cpuset_t map, 858 void (*setup_func)(void *), 859 void (*action_func)(void *), 860 void (*teardown_func)(void *), 861 void *arg) 862 { 863 /* 864 * In the !SMP case we just need to ensure the same initial conditions 865 * as the SMP case. 866 */ 867 spinlock_enter(); 868 if (setup_func != NULL) 869 setup_func(arg); 870 if (action_func != NULL) 871 action_func(arg); 872 if (teardown_func != NULL) 873 teardown_func(arg); 874 spinlock_exit(); 875 } 876 877 void 878 smp_rendezvous(void (*setup_func)(void *), 879 void (*action_func)(void *), 880 void (*teardown_func)(void *), 881 void *arg) 882 { 883 884 smp_rendezvous_cpus(all_cpus, setup_func, action_func, teardown_func, 885 arg); 886 } 887 888 /* 889 * Provide dummy SMP support for UP kernels. Modules that need to use SMP 890 * APIs will still work using this dummy support. 891 */ 892 static void 893 mp_setvariables_for_up(void *dummy) 894 { 895 mp_ncpus = 1; 896 mp_ncores = 1; 897 mp_maxid = PCPU_GET(cpuid); 898 CPU_SETOF(mp_maxid, &all_cpus); 899 KASSERT(PCPU_GET(cpuid) == 0, ("UP must have a CPU ID of zero")); 900 } 901 SYSINIT(cpu_mp_setvariables, SI_SUB_TUNABLES, SI_ORDER_FIRST, 902 mp_setvariables_for_up, NULL); 903 #endif /* SMP */ 904 905 void 906 smp_no_rendezvous_barrier(void *dummy) 907 { 908 #ifdef SMP 909 KASSERT((!smp_started),("smp_no_rendezvous called and smp is started")); 910 #endif 911 } 912 913 void 914 smp_rendezvous_cpus_retry(cpuset_t map, 915 void (* setup_func)(void *), 916 void (* action_func)(void *), 917 void (* teardown_func)(void *), 918 void (* wait_func)(void *, int), 919 struct smp_rendezvous_cpus_retry_arg *arg) 920 { 921 int cpu; 922 923 CPU_COPY(&map, &arg->cpus); 924 925 /* 926 * Only one CPU to execute on. 927 */ 928 if (!smp_started) { 929 spinlock_enter(); 930 if (setup_func != NULL) 931 setup_func(arg); 932 if (action_func != NULL) 933 action_func(arg); 934 if (teardown_func != NULL) 935 teardown_func(arg); 936 spinlock_exit(); 937 return; 938 } 939 940 /* 941 * Execute an action on all specified CPUs while retrying until they 942 * all acknowledge completion. 943 */ 944 for (;;) { 945 smp_rendezvous_cpus( 946 arg->cpus, 947 setup_func, 948 action_func, 949 teardown_func, 950 arg); 951 952 if (CPU_EMPTY(&arg->cpus)) 953 break; 954 955 CPU_FOREACH(cpu) { 956 if (!CPU_ISSET(cpu, &arg->cpus)) 957 continue; 958 wait_func(arg, cpu); 959 } 960 } 961 } 962 963 void 964 smp_rendezvous_cpus_done(struct smp_rendezvous_cpus_retry_arg *arg) 965 { 966 967 CPU_CLR_ATOMIC(curcpu, &arg->cpus); 968 } 969 970 /* 971 * If (prio & PDROP) == 0: 972 * Wait for specified idle threads to switch once. This ensures that even 973 * preempted threads have cycled through the switch function once, 974 * exiting their codepaths. This allows us to change global pointers 975 * with no other synchronization. 976 * If (prio & PDROP) != 0: 977 * Force the specified CPUs to switch context at least once. 978 */ 979 int 980 quiesce_cpus(cpuset_t map, const char *wmesg, int prio) 981 { 982 struct pcpu *pcpu; 983 u_int *gen; 984 int error; 985 int cpu; 986 987 error = 0; 988 if ((prio & PDROP) == 0) { 989 gen = mallocarray(sizeof(u_int), mp_maxid + 1, M_TEMP, 990 M_WAITOK); 991 for (cpu = 0; cpu <= mp_maxid; cpu++) { 992 if (!CPU_ISSET(cpu, &map) || CPU_ABSENT(cpu)) 993 continue; 994 pcpu = pcpu_find(cpu); 995 gen[cpu] = pcpu->pc_idlethread->td_generation; 996 } 997 } 998 for (cpu = 0; cpu <= mp_maxid; cpu++) { 999 if (!CPU_ISSET(cpu, &map) || CPU_ABSENT(cpu)) 1000 continue; 1001 pcpu = pcpu_find(cpu); 1002 thread_lock(curthread); 1003 sched_bind(curthread, cpu); 1004 thread_unlock(curthread); 1005 if ((prio & PDROP) != 0) 1006 continue; 1007 while (gen[cpu] == pcpu->pc_idlethread->td_generation) { 1008 error = tsleep(quiesce_cpus, prio & ~PDROP, wmesg, 1); 1009 if (error != EWOULDBLOCK) 1010 goto out; 1011 error = 0; 1012 } 1013 } 1014 out: 1015 thread_lock(curthread); 1016 sched_unbind(curthread); 1017 thread_unlock(curthread); 1018 if ((prio & PDROP) == 0) 1019 free(gen, M_TEMP); 1020 1021 return (error); 1022 } 1023 1024 int 1025 quiesce_all_cpus(const char *wmesg, int prio) 1026 { 1027 1028 return quiesce_cpus(all_cpus, wmesg, prio); 1029 } 1030 1031 /* 1032 * Observe all CPUs not executing in critical section. 1033 * We are not in one so the check for us is safe. If the found 1034 * thread changes to something else we know the section was 1035 * exited as well. 1036 */ 1037 void 1038 quiesce_all_critical(void) 1039 { 1040 struct thread *td, *newtd; 1041 struct pcpu *pcpu; 1042 int cpu; 1043 1044 MPASS(curthread->td_critnest == 0); 1045 1046 CPU_FOREACH(cpu) { 1047 pcpu = cpuid_to_pcpu[cpu]; 1048 td = pcpu->pc_curthread; 1049 for (;;) { 1050 if (td->td_critnest == 0) 1051 break; 1052 cpu_spinwait(); 1053 newtd = (struct thread *) 1054 atomic_load_acq_ptr((void *)pcpu->pc_curthread); 1055 if (td != newtd) 1056 break; 1057 } 1058 } 1059 } 1060 1061 static void 1062 cpus_fence_seq_cst_issue(void *arg __unused) 1063 { 1064 1065 atomic_thread_fence_seq_cst(); 1066 } 1067 1068 /* 1069 * Send an IPI forcing a sequentially consistent fence. 1070 * 1071 * Allows replacement of an explicitly fence with a compiler barrier. 1072 * Trades speed up during normal execution for a significant slowdown when 1073 * the barrier is needed. 1074 */ 1075 void 1076 cpus_fence_seq_cst(void) 1077 { 1078 1079 #ifdef SMP 1080 smp_rendezvous( 1081 smp_no_rendezvous_barrier, 1082 cpus_fence_seq_cst_issue, 1083 smp_no_rendezvous_barrier, 1084 NULL 1085 ); 1086 #else 1087 cpus_fence_seq_cst_issue(NULL); 1088 #endif 1089 } 1090 1091 /* Extra care is taken with this sysctl because the data type is volatile */ 1092 static int 1093 sysctl_kern_smp_active(SYSCTL_HANDLER_ARGS) 1094 { 1095 int error, active; 1096 1097 active = smp_started; 1098 error = SYSCTL_OUT(req, &active, sizeof(active)); 1099 return (error); 1100 } 1101 1102 #ifdef SMP 1103 void 1104 topo_init_node(struct topo_node *node) 1105 { 1106 1107 bzero(node, sizeof(*node)); 1108 TAILQ_INIT(&node->children); 1109 } 1110 1111 void 1112 topo_init_root(struct topo_node *root) 1113 { 1114 1115 topo_init_node(root); 1116 root->type = TOPO_TYPE_SYSTEM; 1117 } 1118 1119 /* 1120 * Add a child node with the given ID under the given parent. 1121 * Do nothing if there is already a child with that ID. 1122 */ 1123 struct topo_node * 1124 topo_add_node_by_hwid(struct topo_node *parent, int hwid, 1125 topo_node_type type, uintptr_t subtype) 1126 { 1127 struct topo_node *node; 1128 1129 TAILQ_FOREACH_REVERSE(node, &parent->children, 1130 topo_children, siblings) { 1131 if (node->hwid == hwid 1132 && node->type == type && node->subtype == subtype) { 1133 return (node); 1134 } 1135 } 1136 1137 node = malloc(sizeof(*node), M_TOPO, M_WAITOK); 1138 topo_init_node(node); 1139 node->parent = parent; 1140 node->hwid = hwid; 1141 node->type = type; 1142 node->subtype = subtype; 1143 TAILQ_INSERT_TAIL(&parent->children, node, siblings); 1144 parent->nchildren++; 1145 1146 return (node); 1147 } 1148 1149 /* 1150 * Find a child node with the given ID under the given parent. 1151 */ 1152 struct topo_node * 1153 topo_find_node_by_hwid(struct topo_node *parent, int hwid, 1154 topo_node_type type, uintptr_t subtype) 1155 { 1156 1157 struct topo_node *node; 1158 1159 TAILQ_FOREACH(node, &parent->children, siblings) { 1160 if (node->hwid == hwid 1161 && node->type == type && node->subtype == subtype) { 1162 return (node); 1163 } 1164 } 1165 1166 return (NULL); 1167 } 1168 1169 /* 1170 * Given a node change the order of its parent's child nodes such 1171 * that the node becomes the firt child while preserving the cyclic 1172 * order of the children. In other words, the given node is promoted 1173 * by rotation. 1174 */ 1175 void 1176 topo_promote_child(struct topo_node *child) 1177 { 1178 struct topo_node *next; 1179 struct topo_node *node; 1180 struct topo_node *parent; 1181 1182 parent = child->parent; 1183 next = TAILQ_NEXT(child, siblings); 1184 TAILQ_REMOVE(&parent->children, child, siblings); 1185 TAILQ_INSERT_HEAD(&parent->children, child, siblings); 1186 1187 while (next != NULL) { 1188 node = next; 1189 next = TAILQ_NEXT(node, siblings); 1190 TAILQ_REMOVE(&parent->children, node, siblings); 1191 TAILQ_INSERT_AFTER(&parent->children, child, node, siblings); 1192 child = node; 1193 } 1194 } 1195 1196 /* 1197 * Iterate to the next node in the depth-first search (traversal) of 1198 * the topology tree. 1199 */ 1200 struct topo_node * 1201 topo_next_node(struct topo_node *top, struct topo_node *node) 1202 { 1203 struct topo_node *next; 1204 1205 if ((next = TAILQ_FIRST(&node->children)) != NULL) 1206 return (next); 1207 1208 if ((next = TAILQ_NEXT(node, siblings)) != NULL) 1209 return (next); 1210 1211 while (node != top && (node = node->parent) != top) 1212 if ((next = TAILQ_NEXT(node, siblings)) != NULL) 1213 return (next); 1214 1215 return (NULL); 1216 } 1217 1218 /* 1219 * Iterate to the next node in the depth-first search of the topology tree, 1220 * but without descending below the current node. 1221 */ 1222 struct topo_node * 1223 topo_next_nonchild_node(struct topo_node *top, struct topo_node *node) 1224 { 1225 struct topo_node *next; 1226 1227 if ((next = TAILQ_NEXT(node, siblings)) != NULL) 1228 return (next); 1229 1230 while (node != top && (node = node->parent) != top) 1231 if ((next = TAILQ_NEXT(node, siblings)) != NULL) 1232 return (next); 1233 1234 return (NULL); 1235 } 1236 1237 /* 1238 * Assign the given ID to the given topology node that represents a logical 1239 * processor. 1240 */ 1241 void 1242 topo_set_pu_id(struct topo_node *node, cpuid_t id) 1243 { 1244 1245 KASSERT(node->type == TOPO_TYPE_PU, 1246 ("topo_set_pu_id: wrong node type: %u", node->type)); 1247 KASSERT(CPU_EMPTY(&node->cpuset) && node->cpu_count == 0, 1248 ("topo_set_pu_id: cpuset already not empty")); 1249 node->id = id; 1250 CPU_SET(id, &node->cpuset); 1251 node->cpu_count = 1; 1252 node->subtype = 1; 1253 1254 while ((node = node->parent) != NULL) { 1255 KASSERT(!CPU_ISSET(id, &node->cpuset), 1256 ("logical ID %u is already set in node %p", id, node)); 1257 CPU_SET(id, &node->cpuset); 1258 node->cpu_count++; 1259 } 1260 } 1261 1262 static struct topology_spec { 1263 topo_node_type type; 1264 bool match_subtype; 1265 uintptr_t subtype; 1266 } topology_level_table[TOPO_LEVEL_COUNT] = { 1267 [TOPO_LEVEL_PKG] = { .type = TOPO_TYPE_PKG, }, 1268 [TOPO_LEVEL_GROUP] = { .type = TOPO_TYPE_GROUP, }, 1269 [TOPO_LEVEL_CACHEGROUP] = { 1270 .type = TOPO_TYPE_CACHE, 1271 .match_subtype = true, 1272 .subtype = CG_SHARE_L3, 1273 }, 1274 [TOPO_LEVEL_CORE] = { .type = TOPO_TYPE_CORE, }, 1275 [TOPO_LEVEL_THREAD] = { .type = TOPO_TYPE_PU, }, 1276 }; 1277 1278 static bool 1279 topo_analyze_table(struct topo_node *root, int all, enum topo_level level, 1280 struct topo_analysis *results) 1281 { 1282 struct topology_spec *spec; 1283 struct topo_node *node; 1284 int count; 1285 1286 if (level >= TOPO_LEVEL_COUNT) 1287 return (true); 1288 1289 spec = &topology_level_table[level]; 1290 count = 0; 1291 node = topo_next_node(root, root); 1292 1293 while (node != NULL) { 1294 if (node->type != spec->type || 1295 (spec->match_subtype && node->subtype != spec->subtype)) { 1296 node = topo_next_node(root, node); 1297 continue; 1298 } 1299 if (!all && CPU_EMPTY(&node->cpuset)) { 1300 node = topo_next_nonchild_node(root, node); 1301 continue; 1302 } 1303 1304 count++; 1305 1306 if (!topo_analyze_table(node, all, level + 1, results)) 1307 return (false); 1308 1309 node = topo_next_nonchild_node(root, node); 1310 } 1311 1312 /* No explicit subgroups is essentially one subgroup. */ 1313 if (count == 0) { 1314 count = 1; 1315 1316 if (!topo_analyze_table(root, all, level + 1, results)) 1317 return (false); 1318 } 1319 1320 if (results->entities[level] == -1) 1321 results->entities[level] = count; 1322 else if (results->entities[level] != count) 1323 return (false); 1324 1325 return (true); 1326 } 1327 1328 /* 1329 * Check if the topology is uniform, that is, each package has the same number 1330 * of cores in it and each core has the same number of threads (logical 1331 * processors) in it. If so, calculate the number of packages, the number of 1332 * groups per package, the number of cachegroups per group, and the number of 1333 * logical processors per cachegroup. 'all' parameter tells whether to include 1334 * administratively disabled logical processors into the analysis. 1335 */ 1336 int 1337 topo_analyze(struct topo_node *topo_root, int all, 1338 struct topo_analysis *results) 1339 { 1340 1341 results->entities[TOPO_LEVEL_PKG] = -1; 1342 results->entities[TOPO_LEVEL_CORE] = -1; 1343 results->entities[TOPO_LEVEL_THREAD] = -1; 1344 results->entities[TOPO_LEVEL_GROUP] = -1; 1345 results->entities[TOPO_LEVEL_CACHEGROUP] = -1; 1346 1347 if (!topo_analyze_table(topo_root, all, TOPO_LEVEL_PKG, results)) 1348 return (0); 1349 1350 KASSERT(results->entities[TOPO_LEVEL_PKG] > 0, 1351 ("bug in topology or analysis")); 1352 1353 return (1); 1354 } 1355 1356 #endif /* SMP */ 1357