1// SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * x86 SMP booting functions
4 *
5 * (c) 1995 Alan Cox, Building #3 <alan@lxorguk.ukuu.org.uk>
6 * (c) 1998, 1999, 2000, 2009 Ingo Molnar <mingo@redhat.com>
7 * Copyright 2001 Andi Kleen, SuSE Labs.
8 *
9 * Much of the core SMP work is based on previous work by Thomas Radke, to
10 * whom a great many thanks are extended.
11 *
12 * Thanks to Intel for making available several different Pentium,
13 * Pentium Pro and Pentium-II/Xeon MP machines.
14 * Original development of Linux SMP code supported by Caldera.
15 *
16 * Fixes
17 * Felix Koop : NR_CPUS used properly
18 * Jose Renau : Handle single CPU case.
19 * Alan Cox : By repeated request 8) - Total BogoMIPS report.
20 * Greg Wright : Fix for kernel stacks panic.
21 * Erich Boleyn : MP v1.4 and additional changes.
22 * Matthias Sattler : Changes for 2.1 kernel map.
23 * Michel Lespinasse : Changes for 2.1 kernel map.
24 * Michael Chastain : Change trampoline.S to gnu as.
25 * Alan Cox : Dumb bug: 'B' step PPro's are fine
26 * Ingo Molnar : Added APIC timers, based on code
27 * from Jose Renau
28 * Ingo Molnar : various cleanups and rewrites
29 * Tigran Aivazian : fixed "0.00 in /proc/uptime on SMP" bug.
30 * Maciej W. Rozycki : Bits for genuine 82489DX APICs
31 * Andi Kleen : Changed for SMP boot into long mode.
32 * Martin J. Bligh : Added support for multi-quad systems
33 * Dave Jones : Report invalid combinations of Athlon CPUs.
34 * Rusty Russell : Hacked into shape for new "hotplug" boot process.
35 * Andi Kleen : Converted to new state machine.
36 * Ashok Raj : CPU hotplug support
37 * Glauber Costa : i386 and x86_64 integration
38 */
39
40#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
41
42#include <linux/init.h>
43#include <linux/smp.h>
44#include <linux/export.h>
45#include <linux/sched.h>
46#include <linux/sched/topology.h>
47#include <linux/sched/hotplug.h>
48#include <linux/sched/task_stack.h>
49#include <linux/percpu.h>
50#include <linux/memblock.h>
51#include <linux/err.h>
52#include <linux/nmi.h>
53#include <linux/tboot.h>
54#include <linux/gfp.h>
55#include <linux/cpuidle.h>
56#include <linux/kexec.h>
57#include <linux/numa.h>
58#include <linux/pgtable.h>
59#include <linux/overflow.h>
60#include <linux/stackprotector.h>
61#include <linux/cpuhotplug.h>
62#include <linux/mc146818rtc.h>
63#include <linux/acpi.h>
64
65#include <asm/acpi.h>
66#include <asm/cacheinfo.h>
67#include <asm/cpuid/api.h>
68#include <asm/desc.h>
69#include <asm/nmi.h>
70#include <asm/irq.h>
71#include <asm/realmode.h>
72#include <asm/cpu.h>
73#include <asm/numa.h>
74#include <asm/tlbflush.h>
75#include <asm/mtrr.h>
76#include <asm/mwait.h>
77#include <asm/apic.h>
78#include <asm/io_apic.h>
79#include <asm/fpu/api.h>
80#include <asm/setup.h>
81#include <asm/uv/uv.h>
82#include <asm/microcode.h>
83#include <asm/i8259.h>
84#include <asm/misc.h>
85#include <asm/qspinlock.h>
86#include <asm/intel-family.h>
87#include <asm/cpu_device_id.h>
88#include <asm/spec-ctrl.h>
89#include <asm/hw_irq.h>
90#include <asm/stackprotector.h>
91#include <asm/sev.h>
92#include <asm/spec-ctrl.h>
93
94/* representing HT siblings of each logical CPU */
95DEFINE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_sibling_map);
96EXPORT_PER_CPU_SYMBOL(cpu_sibling_map);
97
98/* representing HT and core siblings of each logical CPU */
99DEFINE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_core_map);
100EXPORT_PER_CPU_SYMBOL(cpu_core_map);
101
102/* representing HT, core, and die siblings of each logical CPU */
103DEFINE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_die_map);
104EXPORT_PER_CPU_SYMBOL(cpu_die_map);
105
106/* CPUs which are the primary SMT threads */
107struct cpumask __cpu_primary_thread_mask __read_mostly;
108
109/* Representing CPUs for which sibling maps can be computed */
110static cpumask_var_t cpu_sibling_setup_mask;
111
112struct mwait_cpu_dead {
113 unsigned int control;
114 unsigned int status;
115};
116
117#define CPUDEAD_MWAIT_WAIT 0xDEADBEEF
118#define CPUDEAD_MWAIT_KEXEC_HLT 0x4A17DEAD
119
120/*
121 * Cache line aligned data for mwait_play_dead(). Separate on purpose so
122 * that it's unlikely to be touched by other CPUs.
123 */
124static DEFINE_PER_CPU_ALIGNED(struct mwait_cpu_dead, mwait_cpu_dead);
125
126/* Maximum number of SMT threads on any online core */
127int __read_mostly __max_smt_threads = 1;
128
129/* Flag to indicate if a complete sched domain rebuild is required */
130bool x86_topology_update;
131
132int arch_update_cpu_topology(void)
133{
134 int retval = x86_topology_update;
135
136 x86_topology_update = false;
137 return retval;
138}
139
140static unsigned int smpboot_warm_reset_vector_count;
141
142static inline void smpboot_setup_warm_reset_vector(unsigned long start_eip)
143{
144 unsigned long flags;
145
146 spin_lock_irqsave(&rtc_lock, flags);
147 if (!smpboot_warm_reset_vector_count++) {
148 CMOS_WRITE(0xa, 0xf);
149 *((volatile unsigned short *)phys_to_virt(TRAMPOLINE_PHYS_HIGH)) = start_eip >> 4;
150 *((volatile unsigned short *)phys_to_virt(TRAMPOLINE_PHYS_LOW)) = start_eip & 0xf;
151 }
152 spin_unlock_irqrestore(lock: &rtc_lock, flags);
153}
154
155static inline void smpboot_restore_warm_reset_vector(void)
156{
157 unsigned long flags;
158
159 /*
160 * Paranoid: Set warm reset code and vector here back
161 * to default values.
162 */
163 spin_lock_irqsave(&rtc_lock, flags);
164 if (!--smpboot_warm_reset_vector_count) {
165 CMOS_WRITE(0, 0xf);
166 *((volatile u32 *)phys_to_virt(TRAMPOLINE_PHYS_LOW)) = 0;
167 }
168 spin_unlock_irqrestore(lock: &rtc_lock, flags);
169
170}
171
172/* Run the next set of setup steps for the upcoming CPU */
173static void ap_starting(void)
174{
175 int cpuid = smp_processor_id();
176
177 /* Mop up eventual mwait_play_dead() wreckage */
178 this_cpu_write(mwait_cpu_dead.status, 0);
179 this_cpu_write(mwait_cpu_dead.control, 0);
180
181 /*
182 * If woken up by an INIT in an 82489DX configuration the alive
183 * synchronization guarantees that the CPU does not reach this
184 * point before an INIT_deassert IPI reaches the local APIC, so it
185 * is now safe to touch the local APIC.
186 *
187 * Set up this CPU, first the APIC, which is probably redundant on
188 * most boards.
189 */
190 apic_ap_setup();
191
192 /* Save the processor parameters. */
193 identify_secondary_cpu(cpu: cpuid);
194
195 /*
196 * The topology information must be up to date before
197 * notify_cpu_starting().
198 */
199 set_cpu_sibling_map(cpuid);
200
201 ap_init_aperfmperf();
202
203 pr_debug("Stack at about %p\n", &cpuid);
204
205 wmb();
206
207 /*
208 * This runs the AP through all the cpuhp states to its target
209 * state CPUHP_ONLINE.
210 */
211 notify_cpu_starting(cpu: cpuid);
212}
213
214static void ap_calibrate_delay(void)
215{
216 /*
217 * Calibrate the delay loop and update loops_per_jiffy in cpu_data.
218 * identify_secondary_cpu() stored a value that is close but not as
219 * accurate as the value just calculated.
220 *
221 * As this is invoked after the TSC synchronization check,
222 * calibrate_delay_is_known() will skip the calibration routine
223 * when TSC is synchronized across sockets.
224 */
225 calibrate_delay();
226 cpu_data(smp_processor_id()).loops_per_jiffy = loops_per_jiffy;
227}
228
229/*
230 * Activate a secondary processor.
231 */
232static void notrace __noendbr start_secondary(void *unused)
233{
234 /*
235 * Don't put *anything* except direct CPU state initialization
236 * before cpu_init(), SMP booting is too fragile that we want to
237 * limit the things done here to the most necessary things.
238 */
239 cr4_init();
240
241 /*
242 * 32-bit specific. 64-bit reaches this code with the correct page
243 * table established. Yet another historical divergence.
244 */
245 if (IS_ENABLED(CONFIG_X86_32)) {
246 /* switch away from the initial page table */
247 load_cr3(swapper_pg_dir);
248 __flush_tlb_all();
249 }
250
251 cpu_init_exception_handling(boot_cpu: false);
252
253 /*
254 * Load the microcode before reaching the AP alive synchronization
255 * point below so it is not part of the full per CPU serialized
256 * bringup part when "parallel" bringup is enabled.
257 *
258 * That's even safe when hyperthreading is enabled in the CPU as
259 * the core code starts the primary threads first and leaves the
260 * secondary threads waiting for SIPI. Loading microcode on
261 * physical cores concurrently is a safe operation.
262 *
263 * This covers both the Intel specific issue that concurrent
264 * microcode loading on SMT siblings must be prohibited and the
265 * vendor independent issue`that microcode loading which changes
266 * CPUID, MSRs etc. must be strictly serialized to maintain
267 * software state correctness.
268 */
269 load_ucode_ap();
270
271 /*
272 * Synchronization point with the hotplug core. Sets this CPUs
273 * synchronization state to ALIVE and spin-waits for the control CPU to
274 * release this CPU for further bringup.
275 */
276 cpuhp_ap_sync_alive();
277
278 cpu_init();
279 fpu__init_cpu();
280 rcutree_report_cpu_starting(raw_smp_processor_id());
281 x86_cpuinit.early_percpu_clock_init();
282
283 ap_starting();
284
285 /* Check TSC synchronization with the control CPU. */
286 check_tsc_sync_target();
287
288 /*
289 * Calibrate the delay loop after the TSC synchronization check.
290 * This allows to skip the calibration when TSC is synchronized
291 * across sockets.
292 */
293 ap_calibrate_delay();
294
295 speculative_store_bypass_ht_init();
296
297 /*
298 * Lock vector_lock, set CPU online and bring the vector
299 * allocator online. Online must be set with vector_lock held
300 * to prevent a concurrent irq setup/teardown from seeing a
301 * half valid vector space.
302 */
303 lock_vector_lock();
304 set_cpu_online(smp_processor_id(), online: true);
305 lapic_online();
306 unlock_vector_lock();
307 x86_platform.nmi_init();
308
309 /* enable local interrupts */
310 local_irq_enable();
311
312 x86_cpuinit.setup_percpu_clockev();
313
314 wmb();
315 cpu_startup_entry(state: CPUHP_AP_ONLINE_IDLE);
316}
317ANNOTATE_NOENDBR_SYM(start_secondary);
318
319static bool
320topology_same_node(struct cpuinfo_x86 *c, struct cpuinfo_x86 *o)
321{
322 int cpu1 = c->cpu_index, cpu2 = o->cpu_index;
323
324 return (cpu_to_node(cpu: cpu1) == cpu_to_node(cpu: cpu2));
325}
326
327static bool
328topology_sane(struct cpuinfo_x86 *c, struct cpuinfo_x86 *o, const char *name)
329{
330 int cpu1 = c->cpu_index, cpu2 = o->cpu_index;
331
332 return !WARN_ONCE(!topology_same_node(c, o),
333 "sched: CPU #%d's %s-sibling CPU #%d is not on the same node! "
334 "[node: %d != %d]. Ignoring dependency.\n",
335 cpu1, name, cpu2, cpu_to_node(cpu1), cpu_to_node(cpu2));
336}
337
338#define link_mask(mfunc, c1, c2) \
339do { \
340 cpumask_set_cpu((c1), mfunc(c2)); \
341 cpumask_set_cpu((c2), mfunc(c1)); \
342} while (0)
343
344static bool match_smt(struct cpuinfo_x86 *c, struct cpuinfo_x86 *o)
345{
346 if (boot_cpu_has(X86_FEATURE_TOPOEXT)) {
347 int cpu1 = c->cpu_index, cpu2 = o->cpu_index;
348
349 if (c->topo.pkg_id == o->topo.pkg_id &&
350 c->topo.die_id == o->topo.die_id &&
351 c->topo.amd_node_id == o->topo.amd_node_id &&
352 per_cpu_llc_id(cpu: cpu1) == per_cpu_llc_id(cpu: cpu2)) {
353 if (c->topo.core_id == o->topo.core_id)
354 return topology_sane(c, o, name: "smt");
355
356 if ((c->topo.cu_id != 0xff) &&
357 (o->topo.cu_id != 0xff) &&
358 (c->topo.cu_id == o->topo.cu_id))
359 return topology_sane(c, o, name: "smt");
360 }
361
362 } else if (c->topo.pkg_id == o->topo.pkg_id &&
363 c->topo.die_id == o->topo.die_id &&
364 c->topo.core_id == o->topo.core_id) {
365 return topology_sane(c, o, name: "smt");
366 }
367
368 return false;
369}
370
371static bool match_die(struct cpuinfo_x86 *c, struct cpuinfo_x86 *o)
372{
373 if (c->topo.pkg_id != o->topo.pkg_id || c->topo.die_id != o->topo.die_id)
374 return false;
375
376 if (cpu_feature_enabled(X86_FEATURE_TOPOEXT) && topology_amd_nodes_per_pkg() > 1)
377 return c->topo.amd_node_id == o->topo.amd_node_id;
378
379 return true;
380}
381
382static bool match_l2c(struct cpuinfo_x86 *c, struct cpuinfo_x86 *o)
383{
384 int cpu1 = c->cpu_index, cpu2 = o->cpu_index;
385
386 /* If the arch didn't set up l2c_id, fall back to SMT */
387 if (per_cpu_l2c_id(cpu: cpu1) == BAD_APICID)
388 return match_smt(c, o);
389
390 /* Do not match if L2 cache id does not match: */
391 if (per_cpu_l2c_id(cpu: cpu1) != per_cpu_l2c_id(cpu: cpu2))
392 return false;
393
394 return topology_sane(c, o, name: "l2c");
395}
396
397/*
398 * Unlike the other levels, we do not enforce keeping a
399 * multicore group inside a NUMA node. If this happens, we will
400 * discard the MC level of the topology later.
401 */
402static bool match_pkg(struct cpuinfo_x86 *c, struct cpuinfo_x86 *o)
403{
404 if (c->topo.pkg_id == o->topo.pkg_id)
405 return true;
406 return false;
407}
408
409/*
410 * Define intel_cod_cpu[] for Intel COD (Cluster-on-Die) CPUs.
411 *
412 * Any Intel CPU that has multiple nodes per package and does not
413 * match intel_cod_cpu[] has the SNC (Sub-NUMA Cluster) topology.
414 *
415 * When in SNC mode, these CPUs enumerate an LLC that is shared
416 * by multiple NUMA nodes. The LLC is shared for off-package data
417 * access but private to the NUMA node (half of the package) for
418 * on-package access. CPUID (the source of the information about
419 * the LLC) can only enumerate the cache as shared or unshared,
420 * but not this particular configuration.
421 */
422
423static const struct x86_cpu_id intel_cod_cpu[] = {
424 X86_MATCH_VFM(INTEL_HASWELL_X, 0), /* COD */
425 X86_MATCH_VFM(INTEL_BROADWELL_X, 0), /* COD */
426 X86_MATCH_VFM(INTEL_ANY, 1), /* SNC */
427 {}
428};
429
430static bool match_llc(struct cpuinfo_x86 *c, struct cpuinfo_x86 *o)
431{
432 const struct x86_cpu_id *id = x86_match_cpu(match: intel_cod_cpu);
433 int cpu1 = c->cpu_index, cpu2 = o->cpu_index;
434 bool intel_snc = id && id->driver_data;
435
436 /* Do not match if we do not have a valid APICID for cpu: */
437 if (per_cpu_llc_id(cpu: cpu1) == BAD_APICID)
438 return false;
439
440 /* Do not match if LLC id does not match: */
441 if (per_cpu_llc_id(cpu: cpu1) != per_cpu_llc_id(cpu: cpu2))
442 return false;
443
444 /*
445 * Allow the SNC topology without warning. Return of false
446 * means 'c' does not share the LLC of 'o'. This will be
447 * reflected to userspace.
448 */
449 if (match_pkg(c, o) && !topology_same_node(c, o) && intel_snc)
450 return false;
451
452 return topology_sane(c, o, name: "llc");
453}
454
455
456static inline int x86_sched_itmt_flags(void)
457{
458 return sysctl_sched_itmt_enabled ? SD_ASYM_PACKING : 0;
459}
460
461#ifdef CONFIG_SCHED_MC
462static int x86_core_flags(void)
463{
464 return cpu_core_flags() | x86_sched_itmt_flags();
465}
466#endif
467#ifdef CONFIG_SCHED_CLUSTER
468static int x86_cluster_flags(void)
469{
470 return cpu_cluster_flags() | x86_sched_itmt_flags();
471}
472#endif
473
474/*
475 * Set if a package/die has multiple NUMA nodes inside.
476 * AMD Magny-Cours, Intel Cluster-on-Die, and Intel
477 * Sub-NUMA Clustering have this.
478 */
479static bool x86_has_numa_in_package;
480
481static struct sched_domain_topology_level x86_topology[6];
482
483static void __init build_sched_topology(void)
484{
485 int i = 0;
486
487#ifdef CONFIG_SCHED_SMT
488 x86_topology[i++] = (struct sched_domain_topology_level){
489 cpu_smt_mask, cpu_smt_flags, SD_INIT_NAME(SMT)
490 };
491#endif
492#ifdef CONFIG_SCHED_CLUSTER
493 x86_topology[i++] = (struct sched_domain_topology_level){
494 cpu_clustergroup_mask, x86_cluster_flags, SD_INIT_NAME(CLS)
495 };
496#endif
497#ifdef CONFIG_SCHED_MC
498 x86_topology[i++] = (struct sched_domain_topology_level){
499 cpu_coregroup_mask, x86_core_flags, SD_INIT_NAME(MC)
500 };
501#endif
502 /*
503 * When there is NUMA topology inside the package skip the PKG domain
504 * since the NUMA domains will auto-magically create the right spanning
505 * domains based on the SLIT.
506 */
507 if (!x86_has_numa_in_package) {
508 x86_topology[i++] = (struct sched_domain_topology_level){
509 cpu_cpu_mask, x86_sched_itmt_flags, SD_INIT_NAME(PKG)
510 };
511 }
512
513 /*
514 * There must be one trailing NULL entry left.
515 */
516 BUG_ON(i >= ARRAY_SIZE(x86_topology)-1);
517
518 set_sched_topology(x86_topology);
519}
520
521void set_cpu_sibling_map(int cpu)
522{
523 bool has_smt = __max_threads_per_core > 1;
524 bool has_mp = has_smt || topology_num_cores_per_package() > 1;
525 struct cpuinfo_x86 *c = &cpu_data(cpu);
526 struct cpuinfo_x86 *o;
527 int i, threads;
528
529 cpumask_set_cpu(cpu, dstp: cpu_sibling_setup_mask);
530
531 if (!has_mp) {
532 cpumask_set_cpu(cpu, topology_sibling_cpumask(cpu));
533 cpumask_set_cpu(cpu, dstp: cpu_llc_shared_mask(cpu));
534 cpumask_set_cpu(cpu, dstp: cpu_l2c_shared_mask(cpu));
535 cpumask_set_cpu(cpu, topology_core_cpumask(cpu));
536 cpumask_set_cpu(cpu, topology_die_cpumask(cpu));
537 c->booted_cores = 1;
538 return;
539 }
540
541 for_each_cpu(i, cpu_sibling_setup_mask) {
542 o = &cpu_data(i);
543
544 if (match_pkg(c, o) && !topology_same_node(c, o))
545 x86_has_numa_in_package = true;
546
547 if ((i == cpu) || (has_smt && match_smt(c, o)))
548 link_mask(topology_sibling_cpumask, cpu, i);
549
550 if ((i == cpu) || (has_mp && match_llc(c, o)))
551 link_mask(cpu_llc_shared_mask, cpu, i);
552
553 if ((i == cpu) || (has_mp && match_l2c(c, o)))
554 link_mask(cpu_l2c_shared_mask, cpu, i);
555
556 if ((i == cpu) || (has_mp && match_die(c, o)))
557 link_mask(topology_die_cpumask, cpu, i);
558 }
559
560 threads = cpumask_weight(topology_sibling_cpumask(cpu));
561 if (threads > __max_smt_threads)
562 __max_smt_threads = threads;
563
564 for_each_cpu(i, topology_sibling_cpumask(cpu))
565 cpu_data(i).smt_active = threads > 1;
566
567 /*
568 * This needs a separate iteration over the cpus because we rely on all
569 * topology_sibling_cpumask links to be set-up.
570 */
571 for_each_cpu(i, cpu_sibling_setup_mask) {
572 o = &cpu_data(i);
573
574 if ((i == cpu) || (has_mp && match_pkg(c, o))) {
575 link_mask(topology_core_cpumask, cpu, i);
576
577 /*
578 * Does this new cpu bringup a new core?
579 */
580 if (threads == 1) {
581 /*
582 * for each core in package, increment
583 * the booted_cores for this new cpu
584 */
585 if (cpumask_first(
586 topology_sibling_cpumask(i)) == i)
587 c->booted_cores++;
588 /*
589 * increment the core count for all
590 * the other cpus in this package
591 */
592 if (i != cpu)
593 cpu_data(i).booted_cores++;
594 } else if (i != cpu && !c->booted_cores)
595 c->booted_cores = cpu_data(i).booted_cores;
596 }
597 }
598}
599
600/* maps the cpu to the sched domain representing multi-core */
601const struct cpumask *cpu_coregroup_mask(int cpu)
602{
603 return cpu_llc_shared_mask(cpu);
604}
605
606const struct cpumask *cpu_clustergroup_mask(int cpu)
607{
608 return cpu_l2c_shared_mask(cpu);
609}
610EXPORT_SYMBOL_GPL(cpu_clustergroup_mask);
611
612static void impress_friends(void)
613{
614 int cpu;
615 unsigned long bogosum = 0;
616 /*
617 * Allow the user to impress friends.
618 */
619 pr_debug("Before bogomips\n");
620 for_each_online_cpu(cpu)
621 bogosum += cpu_data(cpu).loops_per_jiffy;
622
623 pr_info("Total of %d processors activated (%lu.%02lu BogoMIPS)\n",
624 num_online_cpus(),
625 bogosum/(500000/HZ),
626 (bogosum/(5000/HZ))%100);
627
628 pr_debug("Before bogocount - setting activated=1\n");
629}
630
631/*
632 * The Multiprocessor Specification 1.4 (1997) example code suggests
633 * that there should be a 10ms delay between the BSP asserting INIT
634 * and de-asserting INIT, when starting a remote processor.
635 * But that slows boot and resume on modern processors, which include
636 * many cores and don't require that delay.
637 *
638 * Cmdline "cpu_init_udelay=" is available to override this delay.
639 */
640#define UDELAY_10MS_LEGACY 10000
641
642static unsigned int init_udelay = UINT_MAX;
643
644static int __init cpu_init_udelay(char *str)
645{
646 get_option(str: &str, pint: &init_udelay);
647
648 return 0;
649}
650early_param("cpu_init_udelay", cpu_init_udelay);
651
652static void __init smp_set_init_udelay(void)
653{
654 /* if cmdline changed it from default, leave it alone */
655 if (init_udelay != UINT_MAX)
656 return;
657
658 /* if modern processor, use no delay */
659 if ((boot_cpu_data.x86_vendor == X86_VENDOR_INTEL && boot_cpu_data.x86_vfm >= INTEL_PENTIUM_PRO) ||
660 (boot_cpu_data.x86_vendor == X86_VENDOR_HYGON && boot_cpu_data.x86 >= 0x18) ||
661 (boot_cpu_data.x86_vendor == X86_VENDOR_AMD && boot_cpu_data.x86 >= 0xF)) {
662 init_udelay = 0;
663 return;
664 }
665 /* else, use legacy delay */
666 init_udelay = UDELAY_10MS_LEGACY;
667}
668
669/*
670 * Wake up AP by INIT, INIT, STARTUP sequence.
671 */
672static void send_init_sequence(u32 phys_apicid)
673{
674 int maxlvt = lapic_get_maxlvt();
675
676 /* Be paranoid about clearing APIC errors. */
677 if (APIC_INTEGRATED(boot_cpu_apic_version)) {
678 /* Due to the Pentium erratum 3AP. */
679 if (maxlvt > 3)
680 apic_write(APIC_ESR, val: 0);
681 apic_read(APIC_ESR);
682 }
683
684 /* Assert INIT on the target CPU */
685 apic_icr_write(APIC_INT_LEVELTRIG | APIC_INT_ASSERT | APIC_DM_INIT, high: phys_apicid);
686 safe_apic_wait_icr_idle();
687
688 udelay(usec: init_udelay);
689
690 /* Deassert INIT on the target CPU */
691 apic_icr_write(APIC_INT_LEVELTRIG | APIC_DM_INIT, high: phys_apicid);
692 safe_apic_wait_icr_idle();
693}
694
695/*
696 * Wake up AP by INIT, INIT, STARTUP sequence.
697 */
698static int wakeup_secondary_cpu_via_init(u32 phys_apicid, unsigned long start_eip, unsigned int cpu)
699{
700 unsigned long send_status = 0, accept_status = 0;
701 int num_starts, j, maxlvt;
702
703 preempt_disable();
704 maxlvt = lapic_get_maxlvt();
705 send_init_sequence(phys_apicid);
706
707 mb();
708
709 /*
710 * Should we send STARTUP IPIs ?
711 *
712 * Determine this based on the APIC version.
713 * If we don't have an integrated APIC, don't send the STARTUP IPIs.
714 */
715 if (APIC_INTEGRATED(boot_cpu_apic_version))
716 num_starts = 2;
717 else
718 num_starts = 0;
719
720 /*
721 * Run STARTUP IPI loop.
722 */
723 pr_debug("#startup loops: %d\n", num_starts);
724
725 for (j = 1; j <= num_starts; j++) {
726 pr_debug("Sending STARTUP #%d\n", j);
727 if (maxlvt > 3) /* Due to the Pentium erratum 3AP. */
728 apic_write(APIC_ESR, val: 0);
729 apic_read(APIC_ESR);
730 pr_debug("After apic_write\n");
731
732 /*
733 * STARTUP IPI
734 */
735
736 /* Target chip */
737 /* Boot on the stack */
738 /* Kick the second */
739 apic_icr_write(APIC_DM_STARTUP | (start_eip >> 12),
740 high: phys_apicid);
741
742 /*
743 * Give the other CPU some time to accept the IPI.
744 */
745 if (init_udelay == 0)
746 udelay(usec: 10);
747 else
748 udelay(usec: 300);
749
750 pr_debug("Startup point 1\n");
751
752 pr_debug("Waiting for send to finish...\n");
753 send_status = safe_apic_wait_icr_idle();
754
755 /*
756 * Give the other CPU some time to accept the IPI.
757 */
758 if (init_udelay == 0)
759 udelay(usec: 10);
760 else
761 udelay(usec: 200);
762
763 if (maxlvt > 3) /* Due to the Pentium erratum 3AP. */
764 apic_write(APIC_ESR, val: 0);
765 accept_status = (apic_read(APIC_ESR) & 0xEF);
766 if (send_status || accept_status)
767 break;
768 }
769 pr_debug("After Startup\n");
770
771 if (send_status)
772 pr_err("APIC never delivered???\n");
773 if (accept_status)
774 pr_err("APIC delivery error (%lx)\n", accept_status);
775
776 preempt_enable();
777 return (send_status | accept_status);
778}
779
780/* reduce the number of lines printed when booting a large cpu count system */
781static void announce_cpu(int cpu, int apicid)
782{
783 static int width, node_width, first = 1;
784 static int current_node = NUMA_NO_NODE;
785 int node = early_cpu_to_node(cpu);
786
787 if (!width)
788 width = num_digits(num_possible_cpus()) + 1; /* + '#' sign */
789
790 if (!node_width)
791 node_width = num_digits(num_possible_nodes()) + 1; /* + '#' */
792
793 if (system_state < SYSTEM_RUNNING) {
794 if (first)
795 pr_info("x86: Booting SMP configuration:\n");
796
797 if (node != current_node) {
798 if (current_node > (-1))
799 pr_cont("\n");
800 current_node = node;
801
802 printk(KERN_INFO ".... node %*s#%d, CPUs: ",
803 node_width - num_digits(node), " ", node);
804 }
805
806 /* Add padding for the BSP */
807 if (first)
808 pr_cont("%*s", width + 1, " ");
809 first = 0;
810
811 pr_cont("%*s#%d", width - num_digits(cpu), " ", cpu);
812 } else
813 pr_info("Booting Node %d Processor %d APIC 0x%x\n",
814 node, cpu, apicid);
815}
816
817int common_cpu_up(unsigned int cpu, struct task_struct *idle)
818{
819 int ret;
820
821 /* Just in case we booted with a single CPU. */
822 alternatives_enable_smp();
823
824 per_cpu(current_task, cpu) = idle;
825 cpu_init_stack_canary(cpu, idle);
826
827 /* Initialize the interrupt stack(s) */
828 ret = irq_init_percpu_irqstack(cpu);
829 if (ret)
830 return ret;
831
832#ifdef CONFIG_X86_32
833 /* Stack for startup_32 can be just as for start_secondary onwards */
834 per_cpu(cpu_current_top_of_stack, cpu) = task_top_of_stack(idle);
835#endif
836 return 0;
837}
838
839/*
840 * NOTE - on most systems this is a PHYSICAL apic ID, but on multiquad
841 * (ie clustered apic addressing mode), this is a LOGICAL apic ID.
842 * Returns zero if startup was successfully sent, else error code from
843 * ->wakeup_secondary_cpu.
844 */
845static int do_boot_cpu(u32 apicid, unsigned int cpu, struct task_struct *idle)
846{
847 unsigned long start_ip = real_mode_header->trampoline_start;
848 int ret;
849
850#ifdef CONFIG_X86_64
851 /* If 64-bit wakeup method exists, use the 64-bit mode trampoline IP */
852 if (apic->wakeup_secondary_cpu_64)
853 start_ip = real_mode_header->trampoline_start64;
854#endif
855 idle->thread.sp = (unsigned long)task_pt_regs(idle);
856 initial_code = (unsigned long)start_secondary;
857
858 if (IS_ENABLED(CONFIG_X86_32)) {
859 early_gdt_descr.address = (unsigned long)get_cpu_gdt_rw(cpu);
860 initial_stack = idle->thread.sp;
861 } else if (!(smpboot_control & STARTUP_PARALLEL_MASK)) {
862 smpboot_control = cpu;
863 }
864
865 /* Enable the espfix hack for this CPU */
866 init_espfix_ap(cpu);
867
868 /* So we see what's up */
869 announce_cpu(cpu, apicid);
870
871 /*
872 * This grunge runs the startup process for
873 * the targeted processor.
874 */
875 if (x86_platform.legacy.warm_reset) {
876
877 pr_debug("Setting warm reset code and vector.\n");
878
879 smpboot_setup_warm_reset_vector(start_eip: start_ip);
880 /*
881 * Be paranoid about clearing APIC errors.
882 */
883 if (APIC_INTEGRATED(boot_cpu_apic_version)) {
884 apic_write(APIC_ESR, val: 0);
885 apic_read(APIC_ESR);
886 }
887 }
888
889 smp_mb();
890
891 /*
892 * Wake up a CPU in difference cases:
893 * - Use a method from the APIC driver if one defined, with wakeup
894 * straight to 64-bit mode preferred over wakeup to RM.
895 * Otherwise,
896 * - Use an INIT boot APIC message
897 */
898 if (apic->wakeup_secondary_cpu_64)
899 ret = apic->wakeup_secondary_cpu_64(apicid, start_ip, cpu);
900 else if (apic->wakeup_secondary_cpu)
901 ret = apic->wakeup_secondary_cpu(apicid, start_ip, cpu);
902 else
903 ret = wakeup_secondary_cpu_via_init(phys_apicid: apicid, start_eip: start_ip, cpu);
904
905 /* If the wakeup mechanism failed, cleanup the warm reset vector */
906 if (ret)
907 arch_cpuhp_cleanup_kick_cpu(cpu);
908 return ret;
909}
910
911int native_kick_ap(unsigned int cpu, struct task_struct *tidle)
912{
913 u32 apicid = apic->cpu_present_to_apicid(cpu);
914 int err;
915
916 lockdep_assert_irqs_enabled();
917
918 pr_debug("++++++++++++++++++++=_---CPU UP %u\n", cpu);
919
920 if (apicid == BAD_APICID || !apic_id_valid(apic_id: apicid)) {
921 pr_err("CPU %u has invalid APIC ID %x. Aborting bringup\n", cpu, apicid);
922 return -EINVAL;
923 }
924
925 if (!test_bit(apicid, phys_cpu_present_map)) {
926 pr_err("CPU %u APIC ID %x is not present. Aborting bringup\n", cpu, apicid);
927 return -EINVAL;
928 }
929
930 /*
931 * Save current MTRR state in case it was changed since early boot
932 * (e.g. by the ACPI SMI) to initialize new CPUs with MTRRs in sync:
933 */
934 mtrr_save_state();
935
936 /* the FPU context is blank, nobody can own it */
937 per_cpu(fpu_fpregs_owner_ctx, cpu) = NULL;
938
939 err = common_cpu_up(cpu, idle: tidle);
940 if (err)
941 return err;
942
943 err = do_boot_cpu(apicid, cpu, idle: tidle);
944 if (err)
945 pr_err("do_boot_cpu failed(%d) to wakeup CPU#%u\n", err, cpu);
946
947 return err;
948}
949
950int arch_cpuhp_kick_ap_alive(unsigned int cpu, struct task_struct *tidle)
951{
952 return smp_ops.kick_ap_alive(cpu, tidle);
953}
954
955void arch_cpuhp_cleanup_kick_cpu(unsigned int cpu)
956{
957 /* Cleanup possible dangling ends... */
958 if (smp_ops.kick_ap_alive == native_kick_ap && x86_platform.legacy.warm_reset)
959 smpboot_restore_warm_reset_vector();
960}
961
962void arch_cpuhp_cleanup_dead_cpu(unsigned int cpu)
963{
964 if (smp_ops.cleanup_dead_cpu)
965 smp_ops.cleanup_dead_cpu(cpu);
966
967 if (system_state == SYSTEM_RUNNING)
968 pr_info("CPU %u is now offline\n", cpu);
969}
970
971void arch_cpuhp_sync_state_poll(void)
972{
973 if (smp_ops.poll_sync_state)
974 smp_ops.poll_sync_state();
975}
976
977/**
978 * arch_disable_smp_support() - Disables SMP support for x86 at boottime
979 */
980void __init arch_disable_smp_support(void)
981{
982 disable_ioapic_support();
983}
984
985/*
986 * Fall back to non SMP mode after errors.
987 *
988 * RED-PEN audit/test this more. I bet there is more state messed up here.
989 */
990static __init void disable_smp(void)
991{
992 pr_info("SMP disabled\n");
993
994 disable_ioapic_support();
995 topology_reset_possible_cpus_up();
996
997 cpumask_set_cpu(cpu: 0, topology_sibling_cpumask(0));
998 cpumask_set_cpu(cpu: 0, topology_core_cpumask(0));
999 cpumask_set_cpu(cpu: 0, topology_die_cpumask(0));
1000}
1001
1002void __init smp_prepare_cpus_common(void)
1003{
1004 unsigned int cpu, node;
1005
1006 /* Mark all except the boot CPU as hotpluggable */
1007 for_each_possible_cpu(cpu) {
1008 if (cpu)
1009 per_cpu(cpu_info.cpu_index, cpu) = nr_cpu_ids;
1010 }
1011
1012 for_each_possible_cpu(cpu) {
1013 node = cpu_to_node(cpu);
1014
1015 zalloc_cpumask_var_node(mask: &per_cpu(cpu_sibling_map, cpu), GFP_KERNEL, node);
1016 zalloc_cpumask_var_node(mask: &per_cpu(cpu_core_map, cpu), GFP_KERNEL, node);
1017 zalloc_cpumask_var_node(mask: &per_cpu(cpu_die_map, cpu), GFP_KERNEL, node);
1018 zalloc_cpumask_var_node(mask: &per_cpu(cpu_llc_shared_map, cpu), GFP_KERNEL, node);
1019 zalloc_cpumask_var_node(mask: &per_cpu(cpu_l2c_shared_map, cpu), GFP_KERNEL, node);
1020 }
1021
1022 set_cpu_sibling_map(0);
1023}
1024
1025void __init smp_prepare_boot_cpu(void)
1026{
1027 smp_ops.smp_prepare_boot_cpu();
1028}
1029
1030#ifdef CONFIG_X86_64
1031/* Establish whether parallel bringup can be supported. */
1032bool __init arch_cpuhp_init_parallel_bringup(void)
1033{
1034 if (!x86_cpuinit.parallel_bringup) {
1035 pr_info("Parallel CPU startup disabled by the platform\n");
1036 return false;
1037 }
1038
1039 smpboot_control = STARTUP_READ_APICID;
1040 pr_debug("Parallel CPU startup enabled: 0x%08x\n", smpboot_control);
1041 return true;
1042}
1043#endif
1044
1045/*
1046 * Prepare for SMP bootup.
1047 * @max_cpus: configured maximum number of CPUs, It is a legacy parameter
1048 * for common interface support.
1049 */
1050void __init native_smp_prepare_cpus(unsigned int max_cpus)
1051{
1052 smp_prepare_cpus_common();
1053
1054 switch (apic_intr_mode) {
1055 case APIC_PIC:
1056 case APIC_VIRTUAL_WIRE_NO_CONFIG:
1057 disable_smp();
1058 return;
1059 case APIC_SYMMETRIC_IO_NO_ROUTING:
1060 disable_smp();
1061 /* Setup local timer */
1062 x86_init.timers.setup_percpu_clockev();
1063 return;
1064 case APIC_VIRTUAL_WIRE:
1065 case APIC_SYMMETRIC_IO:
1066 break;
1067 }
1068
1069 /* Setup local timer */
1070 x86_init.timers.setup_percpu_clockev();
1071
1072 pr_info("CPU0: ");
1073 print_cpu_info(&cpu_data(0));
1074
1075 uv_system_init();
1076
1077 smp_set_init_udelay();
1078
1079 speculative_store_bypass_ht_init();
1080
1081 snp_set_wakeup_secondary_cpu();
1082}
1083
1084void arch_thaw_secondary_cpus_begin(void)
1085{
1086 set_cache_aps_delayed_init(true);
1087}
1088
1089void arch_thaw_secondary_cpus_end(void)
1090{
1091 cache_aps_init();
1092}
1093
1094/*
1095 * Early setup to make printk work.
1096 */
1097void __init native_smp_prepare_boot_cpu(void)
1098{
1099 int me = smp_processor_id();
1100
1101 /* SMP handles this from setup_per_cpu_areas() */
1102 if (!IS_ENABLED(CONFIG_SMP))
1103 switch_gdt_and_percpu_base(me);
1104
1105 native_pv_lock_init();
1106}
1107
1108void __init native_smp_cpus_done(unsigned int max_cpus)
1109{
1110 pr_debug("Boot done\n");
1111
1112 build_sched_topology();
1113 nmi_selftest();
1114 impress_friends();
1115 cache_aps_init();
1116}
1117
1118/* correctly size the local cpu masks */
1119void __init setup_cpu_local_masks(void)
1120{
1121 alloc_bootmem_cpumask_var(mask: &cpu_sibling_setup_mask);
1122}
1123
1124#ifdef CONFIG_HOTPLUG_CPU
1125
1126/* Recompute SMT state for all CPUs on offline */
1127static void recompute_smt_state(void)
1128{
1129 int max_threads, cpu;
1130
1131 max_threads = 0;
1132 for_each_online_cpu (cpu) {
1133 int threads = cpumask_weight(topology_sibling_cpumask(cpu));
1134
1135 if (threads > max_threads)
1136 max_threads = threads;
1137 }
1138 __max_smt_threads = max_threads;
1139}
1140
1141static void remove_siblinginfo(int cpu)
1142{
1143 int sibling;
1144 struct cpuinfo_x86 *c = &cpu_data(cpu);
1145
1146 for_each_cpu(sibling, topology_core_cpumask(cpu)) {
1147 cpumask_clear_cpu(cpu, topology_core_cpumask(sibling));
1148 /*/
1149 * last thread sibling in this cpu core going down
1150 */
1151 if (cpumask_weight(topology_sibling_cpumask(cpu)) == 1)
1152 cpu_data(sibling).booted_cores--;
1153 }
1154
1155 for_each_cpu(sibling, topology_die_cpumask(cpu))
1156 cpumask_clear_cpu(cpu, topology_die_cpumask(sibling));
1157
1158 for_each_cpu(sibling, topology_sibling_cpumask(cpu)) {
1159 cpumask_clear_cpu(cpu, topology_sibling_cpumask(sibling));
1160 if (cpumask_weight(topology_sibling_cpumask(sibling)) == 1)
1161 cpu_data(sibling).smt_active = false;
1162 }
1163
1164 for_each_cpu(sibling, cpu_llc_shared_mask(cpu))
1165 cpumask_clear_cpu(cpu, dstp: cpu_llc_shared_mask(cpu: sibling));
1166 for_each_cpu(sibling, cpu_l2c_shared_mask(cpu))
1167 cpumask_clear_cpu(cpu, dstp: cpu_l2c_shared_mask(cpu: sibling));
1168 cpumask_clear(dstp: cpu_llc_shared_mask(cpu));
1169 cpumask_clear(dstp: cpu_l2c_shared_mask(cpu));
1170 cpumask_clear(topology_sibling_cpumask(cpu));
1171 cpumask_clear(topology_core_cpumask(cpu));
1172 cpumask_clear(topology_die_cpumask(cpu));
1173 c->topo.core_id = 0;
1174 c->booted_cores = 0;
1175 cpumask_clear_cpu(cpu, dstp: cpu_sibling_setup_mask);
1176 recompute_smt_state();
1177}
1178
1179static void remove_cpu_from_maps(int cpu)
1180{
1181 set_cpu_online(cpu, online: false);
1182 numa_remove_cpu(cpu);
1183}
1184
1185void cpu_disable_common(void)
1186{
1187 int cpu = smp_processor_id();
1188
1189 remove_siblinginfo(cpu);
1190
1191 /*
1192 * Stop allowing kernel-mode FPU. This is needed so that if the CPU is
1193 * brought online again, the initial state is not allowed:
1194 */
1195 this_cpu_write(kernel_fpu_allowed, false);
1196
1197 /* It's now safe to remove this processor from the online map */
1198 lock_vector_lock();
1199 remove_cpu_from_maps(cpu);
1200 unlock_vector_lock();
1201 fixup_irqs();
1202 lapic_offline();
1203}
1204
1205int native_cpu_disable(void)
1206{
1207 int ret;
1208
1209 ret = lapic_can_unplug_cpu();
1210 if (ret)
1211 return ret;
1212
1213 cpu_disable_common();
1214
1215 /*
1216 * Disable the local APIC. Otherwise IPI broadcasts will reach
1217 * it. It still responds normally to INIT, NMI, SMI, and SIPI
1218 * messages.
1219 *
1220 * Disabling the APIC must happen after cpu_disable_common()
1221 * which invokes fixup_irqs().
1222 *
1223 * Disabling the APIC preserves already set bits in IRR, but
1224 * an interrupt arriving after disabling the local APIC does not
1225 * set the corresponding IRR bit.
1226 *
1227 * fixup_irqs() scans IRR for set bits so it can raise a not
1228 * yet handled interrupt on the new destination CPU via an IPI
1229 * but obviously it can't do so for IRR bits which are not set.
1230 * IOW, interrupts arriving after disabling the local APIC will
1231 * be lost.
1232 */
1233 apic_soft_disable();
1234
1235 return 0;
1236}
1237
1238void play_dead_common(void)
1239{
1240 idle_task_exit();
1241
1242 cpuhp_ap_report_dead();
1243
1244 local_irq_disable();
1245}
1246
1247void __noreturn mwait_play_dead(unsigned int eax_hint)
1248{
1249 struct mwait_cpu_dead *md = this_cpu_ptr(&mwait_cpu_dead);
1250
1251 /* Set up state for the kexec() hack below */
1252 md->status = CPUDEAD_MWAIT_WAIT;
1253 md->control = CPUDEAD_MWAIT_WAIT;
1254
1255 wbinvd();
1256
1257 while (1) {
1258 /*
1259 * The CLFLUSH is a workaround for erratum AAI65 for
1260 * the Xeon 7400 series. It's not clear it is actually
1261 * needed, but it should be harmless in either case.
1262 * The WBINVD is insufficient due to the spurious-wakeup
1263 * case where we return around the loop.
1264 */
1265 mb();
1266 clflush(p: md);
1267 mb();
1268 __monitor(eax: md, ecx: 0, edx: 0);
1269 mb();
1270 __mwait(eax: eax_hint, ecx: 0);
1271
1272 if (READ_ONCE(md->control) == CPUDEAD_MWAIT_KEXEC_HLT) {
1273 /*
1274 * Kexec is about to happen. Don't go back into mwait() as
1275 * the kexec kernel might overwrite text and data including
1276 * page tables and stack. So mwait() would resume when the
1277 * monitor cache line is written to and then the CPU goes
1278 * south due to overwritten text, page tables and stack.
1279 *
1280 * Note: This does _NOT_ protect against a stray MCE, NMI,
1281 * SMI. They will resume execution at the instruction
1282 * following the HLT instruction and run into the problem
1283 * which this is trying to prevent.
1284 */
1285 WRITE_ONCE(md->status, CPUDEAD_MWAIT_KEXEC_HLT);
1286 while(1)
1287 native_halt();
1288 }
1289 }
1290}
1291
1292/*
1293 * We need to flush the caches before going to sleep, lest we have
1294 * dirty data in our caches when we come back up.
1295 */
1296static inline void mwait_play_dead_cpuid_hint(void)
1297{
1298 unsigned int eax, ebx, ecx, edx;
1299 unsigned int highest_cstate = 0;
1300 unsigned int highest_subcstate = 0;
1301 int i;
1302
1303 if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD ||
1304 boot_cpu_data.x86_vendor == X86_VENDOR_HYGON)
1305 return;
1306 if (!this_cpu_has(X86_FEATURE_MWAIT))
1307 return;
1308 if (!this_cpu_has(X86_FEATURE_CLFLUSH))
1309 return;
1310
1311 eax = CPUID_LEAF_MWAIT;
1312 ecx = 0;
1313 native_cpuid(eax: &eax, ebx: &ebx, ecx: &ecx, edx: &edx);
1314
1315 /*
1316 * eax will be 0 if EDX enumeration is not valid.
1317 * Initialized below to cstate, sub_cstate value when EDX is valid.
1318 */
1319 if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED)) {
1320 eax = 0;
1321 } else {
1322 edx >>= MWAIT_SUBSTATE_SIZE;
1323 for (i = 0; i < 7 && edx; i++, edx >>= MWAIT_SUBSTATE_SIZE) {
1324 if (edx & MWAIT_SUBSTATE_MASK) {
1325 highest_cstate = i;
1326 highest_subcstate = edx & MWAIT_SUBSTATE_MASK;
1327 }
1328 }
1329 eax = (highest_cstate << MWAIT_SUBSTATE_SIZE) |
1330 (highest_subcstate - 1);
1331 }
1332
1333 mwait_play_dead(eax_hint: eax);
1334}
1335
1336/*
1337 * Kick all "offline" CPUs out of mwait on kexec(). See comment in
1338 * mwait_play_dead().
1339 */
1340void smp_kick_mwait_play_dead(void)
1341{
1342 u32 newstate = CPUDEAD_MWAIT_KEXEC_HLT;
1343 struct mwait_cpu_dead *md;
1344 unsigned int cpu, i;
1345
1346 for_each_cpu_andnot(cpu, cpu_present_mask, cpu_online_mask) {
1347 md = per_cpu_ptr(&mwait_cpu_dead, cpu);
1348
1349 /* Does it sit in mwait_play_dead() ? */
1350 if (READ_ONCE(md->status) != CPUDEAD_MWAIT_WAIT)
1351 continue;
1352
1353 /* Wait up to 5ms */
1354 for (i = 0; READ_ONCE(md->status) != newstate && i < 1000; i++) {
1355 /* Bring it out of mwait */
1356 WRITE_ONCE(md->control, newstate);
1357 udelay(usec: 5);
1358 }
1359
1360 if (READ_ONCE(md->status) != newstate)
1361 pr_err_once("CPU%u is stuck in mwait_play_dead()\n", cpu);
1362 }
1363}
1364
1365void __noreturn hlt_play_dead(void)
1366{
1367 if (__this_cpu_read(cpu_info.x86) >= 4)
1368 wbinvd();
1369
1370 while (1)
1371 native_halt();
1372}
1373
1374/*
1375 * native_play_dead() is essentially a __noreturn function, but it can't
1376 * be marked as such as the compiler may complain about it.
1377 */
1378void native_play_dead(void)
1379{
1380 if (cpu_feature_enabled(X86_FEATURE_KERNEL_IBRS))
1381 __update_spec_ctrl(val: 0);
1382
1383 play_dead_common();
1384 tboot_shutdown(shutdown_type: TB_SHUTDOWN_WFS);
1385
1386 mwait_play_dead_cpuid_hint();
1387 if (cpuidle_play_dead())
1388 hlt_play_dead();
1389}
1390
1391#else /* ... !CONFIG_HOTPLUG_CPU */
1392int native_cpu_disable(void)
1393{
1394 return -ENOSYS;
1395}
1396
1397void native_play_dead(void)
1398{
1399 BUG();
1400}
1401
1402#endif
1403

Provided by KDAB

Privacy Policy
Improve your Profiling and Debugging skills
Find out more

source code of linux/arch/x86/kernel/smpboot.c