1// SPDX-License-Identifier: GPL-2.0
2#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
3
4#include <linux/export.h>
5#include <linux/reboot.h>
6#include <linux/init.h>
7#include <linux/pm.h>
8#include <linux/efi.h>
9#include <linux/dmi.h>
10#include <linux/sched.h>
11#include <linux/tboot.h>
12#include <linux/delay.h>
13#include <linux/objtool.h>
14#include <linux/pgtable.h>
15#include <linux/kexec.h>
16#include <acpi/reboot.h>
17#include <asm/io.h>
18#include <asm/apic.h>
19#include <asm/io_apic.h>
20#include <asm/desc.h>
21#include <asm/hpet.h>
22#include <asm/proto.h>
23#include <asm/reboot_fixups.h>
24#include <asm/reboot.h>
25#include <asm/pci_x86.h>
26#include <asm/cpu.h>
27#include <asm/nmi.h>
28#include <asm/smp.h>
29
30#include <linux/ctype.h>
31#include <linux/mc146818rtc.h>
32#include <asm/realmode.h>
33#include <asm/x86_init.h>
34#include <asm/efi.h>
35
36/*
37 * Power off function, if any
38 */
39void (*pm_power_off)(void);
40EXPORT_SYMBOL(pm_power_off);
41
42/*
43 * This is set if we need to go through the 'emergency' path.
44 * When machine_emergency_restart() is called, we may be on
45 * an inconsistent state and won't be able to do a clean cleanup
46 */
47static int reboot_emergency;
48
49/* This is set by the PCI code if either type 1 or type 2 PCI is detected */
50bool port_cf9_safe = false;
51
52/*
53 * Reboot options and system auto-detection code provided by
54 * Dell Inc. so their systems "just work". :-)
55 */
56
57/*
58 * Some machines require the "reboot=a" commandline options
59 */
60static int __init set_acpi_reboot(const struct dmi_system_id *d)
61{
62 if (reboot_type != BOOT_ACPI) {
63 reboot_type = BOOT_ACPI;
64 pr_info("%s series board detected. Selecting %s-method for reboots.\n",
65 d->ident, "ACPI");
66 }
67 return 0;
68}
69
70/*
71 * Some machines require the "reboot=b" or "reboot=k" commandline options,
72 * this quirk makes that automatic.
73 */
74static int __init set_bios_reboot(const struct dmi_system_id *d)
75{
76 if (reboot_type != BOOT_BIOS) {
77 reboot_type = BOOT_BIOS;
78 pr_info("%s series board detected. Selecting %s-method for reboots.\n",
79 d->ident, "BIOS");
80 }
81 return 0;
82}
83
84/*
85 * Some machines don't handle the default ACPI reboot method and
86 * require the EFI reboot method:
87 */
88static int __init set_efi_reboot(const struct dmi_system_id *d)
89{
90 if (reboot_type != BOOT_EFI && !efi_runtime_disabled()) {
91 reboot_type = BOOT_EFI;
92 pr_info("%s series board detected. Selecting EFI-method for reboot.\n", d->ident);
93 }
94 return 0;
95}
96
97void __noreturn machine_real_restart(unsigned int type)
98{
99 local_irq_disable();
100
101 /*
102 * Write zero to CMOS register number 0x0f, which the BIOS POST
103 * routine will recognize as telling it to do a proper reboot. (Well
104 * that's what this book in front of me says -- it may only apply to
105 * the Phoenix BIOS though, it's not clear). At the same time,
106 * disable NMIs by setting the top bit in the CMOS address register,
107 * as we're about to do peculiar things to the CPU. I'm not sure if
108 * `outb_p' is needed instead of just `outb'. Use it to be on the
109 * safe side. (Yes, CMOS_WRITE does outb_p's. - Paul G.)
110 */
111 spin_lock(lock: &rtc_lock);
112 CMOS_WRITE(0x00, 0x8f);
113 spin_unlock(lock: &rtc_lock);
114
115 /*
116 * Switch to the trampoline page table.
117 */
118 load_trampoline_pgtable();
119
120 /* Jump to the identity-mapped low memory code */
121#ifdef CONFIG_X86_32
122 asm volatile("jmpl *%0" : :
123 "rm" (real_mode_header->machine_real_restart_asm),
124 "a" (type));
125#else
126 asm volatile("ljmpl *%0" : :
127 "m" (real_mode_header->machine_real_restart_asm),
128 "D" (type));
129#endif
130 unreachable();
131}
132#ifdef CONFIG_APM_MODULE
133EXPORT_SYMBOL(machine_real_restart);
134#endif
135STACK_FRAME_NON_STANDARD(machine_real_restart);
136
137/*
138 * Some Apple MacBook and MacBookPro's needs reboot=p to be able to reboot
139 */
140static int __init set_pci_reboot(const struct dmi_system_id *d)
141{
142 if (reboot_type != BOOT_CF9_FORCE) {
143 reboot_type = BOOT_CF9_FORCE;
144 pr_info("%s series board detected. Selecting %s-method for reboots.\n",
145 d->ident, "PCI");
146 }
147 return 0;
148}
149
150static int __init set_kbd_reboot(const struct dmi_system_id *d)
151{
152 if (reboot_type != BOOT_KBD) {
153 reboot_type = BOOT_KBD;
154 pr_info("%s series board detected. Selecting %s-method for reboot.\n",
155 d->ident, "KBD");
156 }
157 return 0;
158}
159
160/*
161 * This is a single dmi_table handling all reboot quirks.
162 */
163static const struct dmi_system_id reboot_dmi_table[] __initconst = {
164
165 /* Acer */
166 { /* Handle reboot issue on Acer Aspire one */
167 .callback = set_kbd_reboot,
168 .ident = "Acer Aspire One A110",
169 .matches = {
170 DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
171 DMI_MATCH(DMI_PRODUCT_NAME, "AOA110"),
172 },
173 },
174 { /* Handle reboot issue on Acer TravelMate X514-51T */
175 .callback = set_efi_reboot,
176 .ident = "Acer TravelMate X514-51T",
177 .matches = {
178 DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
179 DMI_MATCH(DMI_PRODUCT_NAME, "TravelMate X514-51T"),
180 },
181 },
182
183 /* Apple */
184 { /* Handle problems with rebooting on Apple MacBook5 */
185 .callback = set_pci_reboot,
186 .ident = "Apple MacBook5",
187 .matches = {
188 DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
189 DMI_MATCH(DMI_PRODUCT_NAME, "MacBook5"),
190 },
191 },
192 { /* Handle problems with rebooting on Apple MacBook6,1 */
193 .callback = set_pci_reboot,
194 .ident = "Apple MacBook6,1",
195 .matches = {
196 DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
197 DMI_MATCH(DMI_PRODUCT_NAME, "MacBook6,1"),
198 },
199 },
200 { /* Handle problems with rebooting on Apple MacBookPro5 */
201 .callback = set_pci_reboot,
202 .ident = "Apple MacBookPro5",
203 .matches = {
204 DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
205 DMI_MATCH(DMI_PRODUCT_NAME, "MacBookPro5"),
206 },
207 },
208 { /* Handle problems with rebooting on Apple Macmini3,1 */
209 .callback = set_pci_reboot,
210 .ident = "Apple Macmini3,1",
211 .matches = {
212 DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
213 DMI_MATCH(DMI_PRODUCT_NAME, "Macmini3,1"),
214 },
215 },
216 { /* Handle problems with rebooting on the iMac9,1. */
217 .callback = set_pci_reboot,
218 .ident = "Apple iMac9,1",
219 .matches = {
220 DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
221 DMI_MATCH(DMI_PRODUCT_NAME, "iMac9,1"),
222 },
223 },
224 { /* Handle problems with rebooting on the iMac10,1. */
225 .callback = set_pci_reboot,
226 .ident = "Apple iMac10,1",
227 .matches = {
228 DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
229 DMI_MATCH(DMI_PRODUCT_NAME, "iMac10,1"),
230 },
231 },
232
233 /* ASRock */
234 { /* Handle problems with rebooting on ASRock Q1900DC-ITX */
235 .callback = set_pci_reboot,
236 .ident = "ASRock Q1900DC-ITX",
237 .matches = {
238 DMI_MATCH(DMI_BOARD_VENDOR, "ASRock"),
239 DMI_MATCH(DMI_BOARD_NAME, "Q1900DC-ITX"),
240 },
241 },
242
243 /* ASUS */
244 { /* Handle problems with rebooting on ASUS P4S800 */
245 .callback = set_bios_reboot,
246 .ident = "ASUS P4S800",
247 .matches = {
248 DMI_MATCH(DMI_BOARD_VENDOR, "ASUSTeK Computer INC."),
249 DMI_MATCH(DMI_BOARD_NAME, "P4S800"),
250 },
251 },
252 { /* Handle problems with rebooting on ASUS EeeBook X205TA */
253 .callback = set_acpi_reboot,
254 .ident = "ASUS EeeBook X205TA",
255 .matches = {
256 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
257 DMI_MATCH(DMI_PRODUCT_NAME, "X205TA"),
258 },
259 },
260 { /* Handle problems with rebooting on ASUS EeeBook X205TAW */
261 .callback = set_acpi_reboot,
262 .ident = "ASUS EeeBook X205TAW",
263 .matches = {
264 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
265 DMI_MATCH(DMI_PRODUCT_NAME, "X205TAW"),
266 },
267 },
268
269 /* Certec */
270 { /* Handle problems with rebooting on Certec BPC600 */
271 .callback = set_pci_reboot,
272 .ident = "Certec BPC600",
273 .matches = {
274 DMI_MATCH(DMI_SYS_VENDOR, "Certec"),
275 DMI_MATCH(DMI_PRODUCT_NAME, "BPC600"),
276 },
277 },
278
279 /* Dell */
280 { /* Handle problems with rebooting on Dell DXP061 */
281 .callback = set_bios_reboot,
282 .ident = "Dell DXP061",
283 .matches = {
284 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
285 DMI_MATCH(DMI_PRODUCT_NAME, "Dell DXP061"),
286 },
287 },
288 { /* Handle problems with rebooting on Dell E520's */
289 .callback = set_bios_reboot,
290 .ident = "Dell E520",
291 .matches = {
292 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
293 DMI_MATCH(DMI_PRODUCT_NAME, "Dell DM061"),
294 },
295 },
296 { /* Handle problems with rebooting on the Latitude E5410. */
297 .callback = set_pci_reboot,
298 .ident = "Dell Latitude E5410",
299 .matches = {
300 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
301 DMI_MATCH(DMI_PRODUCT_NAME, "Latitude E5410"),
302 },
303 },
304 { /* Handle problems with rebooting on the Latitude E5420. */
305 .callback = set_pci_reboot,
306 .ident = "Dell Latitude E5420",
307 .matches = {
308 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
309 DMI_MATCH(DMI_PRODUCT_NAME, "Latitude E5420"),
310 },
311 },
312 { /* Handle problems with rebooting on the Latitude E6320. */
313 .callback = set_pci_reboot,
314 .ident = "Dell Latitude E6320",
315 .matches = {
316 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
317 DMI_MATCH(DMI_PRODUCT_NAME, "Latitude E6320"),
318 },
319 },
320 { /* Handle problems with rebooting on the Latitude E6420. */
321 .callback = set_pci_reboot,
322 .ident = "Dell Latitude E6420",
323 .matches = {
324 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
325 DMI_MATCH(DMI_PRODUCT_NAME, "Latitude E6420"),
326 },
327 },
328 { /* Handle problems with rebooting on Dell Optiplex 330 with 0KP561 */
329 .callback = set_bios_reboot,
330 .ident = "Dell OptiPlex 330",
331 .matches = {
332 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
333 DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 330"),
334 DMI_MATCH(DMI_BOARD_NAME, "0KP561"),
335 },
336 },
337 { /* Handle problems with rebooting on Dell Optiplex 360 with 0T656F */
338 .callback = set_bios_reboot,
339 .ident = "Dell OptiPlex 360",
340 .matches = {
341 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
342 DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 360"),
343 DMI_MATCH(DMI_BOARD_NAME, "0T656F"),
344 },
345 },
346 { /* Handle problems with rebooting on Dell Optiplex 745's SFF */
347 .callback = set_bios_reboot,
348 .ident = "Dell OptiPlex 745",
349 .matches = {
350 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
351 DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 745"),
352 },
353 },
354 { /* Handle problems with rebooting on Dell Optiplex 745's DFF */
355 .callback = set_bios_reboot,
356 .ident = "Dell OptiPlex 745",
357 .matches = {
358 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
359 DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 745"),
360 DMI_MATCH(DMI_BOARD_NAME, "0MM599"),
361 },
362 },
363 { /* Handle problems with rebooting on Dell Optiplex 745 with 0KW626 */
364 .callback = set_bios_reboot,
365 .ident = "Dell OptiPlex 745",
366 .matches = {
367 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
368 DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 745"),
369 DMI_MATCH(DMI_BOARD_NAME, "0KW626"),
370 },
371 },
372 { /* Handle problems with rebooting on Dell OptiPlex 760 with 0G919G */
373 .callback = set_bios_reboot,
374 .ident = "Dell OptiPlex 760",
375 .matches = {
376 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
377 DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 760"),
378 DMI_MATCH(DMI_BOARD_NAME, "0G919G"),
379 },
380 },
381 { /* Handle problems with rebooting on the OptiPlex 990. */
382 .callback = set_pci_reboot,
383 .ident = "Dell OptiPlex 990 BIOS A0x",
384 .matches = {
385 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
386 DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 990"),
387 DMI_MATCH(DMI_BIOS_VERSION, "A0"),
388 },
389 },
390 { /* Handle problems with rebooting on Dell 300's */
391 .callback = set_bios_reboot,
392 .ident = "Dell PowerEdge 300",
393 .matches = {
394 DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer Corporation"),
395 DMI_MATCH(DMI_PRODUCT_NAME, "PowerEdge 300/"),
396 },
397 },
398 { /* Handle problems with rebooting on Dell 1300's */
399 .callback = set_bios_reboot,
400 .ident = "Dell PowerEdge 1300",
401 .matches = {
402 DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer Corporation"),
403 DMI_MATCH(DMI_PRODUCT_NAME, "PowerEdge 1300/"),
404 },
405 },
406 { /* Handle problems with rebooting on Dell 2400's */
407 .callback = set_bios_reboot,
408 .ident = "Dell PowerEdge 2400",
409 .matches = {
410 DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer Corporation"),
411 DMI_MATCH(DMI_PRODUCT_NAME, "PowerEdge 2400"),
412 },
413 },
414 { /* Handle problems with rebooting on the Dell PowerEdge C6100. */
415 .callback = set_pci_reboot,
416 .ident = "Dell PowerEdge C6100",
417 .matches = {
418 DMI_MATCH(DMI_SYS_VENDOR, "Dell"),
419 DMI_MATCH(DMI_PRODUCT_NAME, "C6100"),
420 },
421 },
422 { /* Handle problems with rebooting on the Precision M6600. */
423 .callback = set_pci_reboot,
424 .ident = "Dell Precision M6600",
425 .matches = {
426 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
427 DMI_MATCH(DMI_PRODUCT_NAME, "Precision M6600"),
428 },
429 },
430 { /* Handle problems with rebooting on Dell T5400's */
431 .callback = set_bios_reboot,
432 .ident = "Dell Precision T5400",
433 .matches = {
434 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
435 DMI_MATCH(DMI_PRODUCT_NAME, "Precision WorkStation T5400"),
436 },
437 },
438 { /* Handle problems with rebooting on Dell T7400's */
439 .callback = set_bios_reboot,
440 .ident = "Dell Precision T7400",
441 .matches = {
442 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
443 DMI_MATCH(DMI_PRODUCT_NAME, "Precision WorkStation T7400"),
444 },
445 },
446 { /* Handle problems with rebooting on Dell XPS710 */
447 .callback = set_bios_reboot,
448 .ident = "Dell XPS710",
449 .matches = {
450 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
451 DMI_MATCH(DMI_PRODUCT_NAME, "Dell XPS710"),
452 },
453 },
454 { /* Handle problems with rebooting on Dell Optiplex 7450 AIO */
455 .callback = set_acpi_reboot,
456 .ident = "Dell OptiPlex 7450 AIO",
457 .matches = {
458 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
459 DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 7450 AIO"),
460 },
461 },
462
463 /* Hewlett-Packard */
464 { /* Handle problems with rebooting on HP laptops */
465 .callback = set_bios_reboot,
466 .ident = "HP Compaq Laptop",
467 .matches = {
468 DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
469 DMI_MATCH(DMI_PRODUCT_NAME, "HP Compaq"),
470 },
471 },
472
473 { /* PCIe Wifi card isn't detected after reboot otherwise */
474 .callback = set_pci_reboot,
475 .ident = "Zotac ZBOX CI327 nano",
476 .matches = {
477 DMI_MATCH(DMI_SYS_VENDOR, "NA"),
478 DMI_MATCH(DMI_PRODUCT_NAME, "ZBOX-CI327NANO-GS-01"),
479 },
480 },
481
482 /* Sony */
483 { /* Handle problems with rebooting on Sony VGN-Z540N */
484 .callback = set_bios_reboot,
485 .ident = "Sony VGN-Z540N",
486 .matches = {
487 DMI_MATCH(DMI_SYS_VENDOR, "Sony Corporation"),
488 DMI_MATCH(DMI_PRODUCT_NAME, "VGN-Z540N"),
489 },
490 },
491
492 { }
493};
494
495static int __init reboot_init(void)
496{
497 int rv;
498
499 /*
500 * Only do the DMI check if reboot_type hasn't been overridden
501 * on the command line
502 */
503 if (!reboot_default)
504 return 0;
505
506 /*
507 * The DMI quirks table takes precedence. If no quirks entry
508 * matches and the ACPI Hardware Reduced bit is set and EFI
509 * runtime services are enabled, force EFI reboot.
510 */
511 rv = dmi_check_system(list: reboot_dmi_table);
512
513 if (!rv && efi_reboot_required() && !efi_runtime_disabled())
514 reboot_type = BOOT_EFI;
515
516 return 0;
517}
518core_initcall(reboot_init);
519
520static inline void kb_wait(void)
521{
522 int i;
523
524 for (i = 0; i < 0x10000; i++) {
525 if ((inb(port: 0x64) & 0x02) == 0)
526 break;
527 udelay(usec: 2);
528 }
529}
530
531static inline void nmi_shootdown_cpus_on_restart(void);
532
533#if IS_ENABLED(CONFIG_KVM_X86)
534/* RCU-protected callback to disable virtualization prior to reboot. */
535static cpu_emergency_virt_cb __rcu *cpu_emergency_virt_callback;
536
537void cpu_emergency_register_virt_callback(cpu_emergency_virt_cb *callback)
538{
539 if (WARN_ON_ONCE(rcu_access_pointer(cpu_emergency_virt_callback)))
540 return;
541
542 rcu_assign_pointer(cpu_emergency_virt_callback, callback);
543}
544EXPORT_SYMBOL_GPL(cpu_emergency_register_virt_callback);
545
546void cpu_emergency_unregister_virt_callback(cpu_emergency_virt_cb *callback)
547{
548 if (WARN_ON_ONCE(rcu_access_pointer(cpu_emergency_virt_callback) != callback))
549 return;
550
551 rcu_assign_pointer(cpu_emergency_virt_callback, NULL);
552 synchronize_rcu();
553}
554EXPORT_SYMBOL_GPL(cpu_emergency_unregister_virt_callback);
555
556/*
557 * Disable virtualization, i.e. VMX or SVM, to ensure INIT is recognized during
558 * reboot. VMX blocks INIT if the CPU is post-VMXON, and SVM blocks INIT if
559 * GIF=0, i.e. if the crash occurred between CLGI and STGI.
560 */
561void cpu_emergency_disable_virtualization(void)
562{
563 cpu_emergency_virt_cb *callback;
564
565 /*
566 * IRQs must be disabled as KVM enables virtualization in hardware via
567 * function call IPIs, i.e. IRQs need to be disabled to guarantee
568 * virtualization stays disabled.
569 */
570 lockdep_assert_irqs_disabled();
571
572 rcu_read_lock();
573 callback = rcu_dereference(cpu_emergency_virt_callback);
574 if (callback)
575 callback();
576 rcu_read_unlock();
577}
578
579static void emergency_reboot_disable_virtualization(void)
580{
581 local_irq_disable();
582
583 /*
584 * Disable virtualization on all CPUs before rebooting to avoid hanging
585 * the system, as VMX and SVM block INIT when running in the host.
586 *
587 * We can't take any locks and we may be on an inconsistent state, so
588 * use NMIs as IPIs to tell the other CPUs to disable VMX/SVM and halt.
589 *
590 * Do the NMI shootdown even if virtualization is off on _this_ CPU, as
591 * other CPUs may have virtualization enabled.
592 */
593 if (rcu_access_pointer(cpu_emergency_virt_callback)) {
594 /* Safely force _this_ CPU out of VMX/SVM operation. */
595 cpu_emergency_disable_virtualization();
596
597 /* Disable VMX/SVM and halt on other CPUs. */
598 nmi_shootdown_cpus_on_restart();
599 }
600}
601#else
602static void emergency_reboot_disable_virtualization(void) { }
603#endif /* CONFIG_KVM_X86 */
604
605void __attribute__((weak)) mach_reboot_fixups(void)
606{
607}
608
609/*
610 * To the best of our knowledge Windows compatible x86 hardware expects
611 * the following on reboot:
612 *
613 * 1) If the FADT has the ACPI reboot register flag set, try it
614 * 2) If still alive, write to the keyboard controller
615 * 3) If still alive, write to the ACPI reboot register again
616 * 4) If still alive, write to the keyboard controller again
617 * 5) If still alive, call the EFI runtime service to reboot
618 * 6) If no EFI runtime service, call the BIOS to do a reboot
619 *
620 * We default to following the same pattern. We also have
621 * two other reboot methods: 'triple fault' and 'PCI', which
622 * can be triggered via the reboot= kernel boot option or
623 * via quirks.
624 *
625 * This means that this function can never return, it can misbehave
626 * by not rebooting properly and hanging.
627 */
628static void native_machine_emergency_restart(void)
629{
630 int i;
631 int attempt = 0;
632 int orig_reboot_type = reboot_type;
633 unsigned short mode;
634
635 if (reboot_emergency)
636 emergency_reboot_disable_virtualization();
637
638 tboot_shutdown(shutdown_type: TB_SHUTDOWN_REBOOT);
639
640 /* Tell the BIOS if we want cold or warm reboot */
641 mode = reboot_mode == REBOOT_WARM ? 0x1234 : 0;
642 *((unsigned short *)__va(0x472)) = mode;
643
644 /*
645 * If an EFI capsule has been registered with the firmware then
646 * override the reboot= parameter.
647 */
648 if (efi_capsule_pending(NULL)) {
649 pr_info("EFI capsule is pending, forcing EFI reboot.\n");
650 reboot_type = BOOT_EFI;
651 }
652
653 for (;;) {
654 /* Could also try the reset bit in the Hammer NB */
655 switch (reboot_type) {
656 case BOOT_ACPI:
657 acpi_reboot();
658 reboot_type = BOOT_KBD;
659 break;
660
661 case BOOT_KBD:
662 mach_reboot_fixups(); /* For board specific fixups */
663
664 for (i = 0; i < 10; i++) {
665 kb_wait();
666 udelay(usec: 50);
667 outb(value: 0xfe, port: 0x64); /* Pulse reset low */
668 udelay(usec: 50);
669 }
670 if (attempt == 0 && orig_reboot_type == BOOT_ACPI) {
671 attempt = 1;
672 reboot_type = BOOT_ACPI;
673 } else {
674 reboot_type = BOOT_EFI;
675 }
676 break;
677
678 case BOOT_EFI:
679 efi_reboot(reboot_mode, NULL);
680 reboot_type = BOOT_BIOS;
681 break;
682
683 case BOOT_BIOS:
684 machine_real_restart(MRR_BIOS);
685
686 /* We're probably dead after this, but... */
687 reboot_type = BOOT_CF9_SAFE;
688 break;
689
690 case BOOT_CF9_FORCE:
691 port_cf9_safe = true;
692 fallthrough;
693
694 case BOOT_CF9_SAFE:
695 if (port_cf9_safe) {
696 u8 reboot_code = reboot_mode == REBOOT_WARM ? 0x06 : 0x0E;
697 u8 cf9 = inb(port: 0xcf9) & ~reboot_code;
698 outb(value: cf9|2, port: 0xcf9); /* Request hard reset */
699 udelay(usec: 50);
700 /* Actually do the reset */
701 outb(value: cf9|reboot_code, port: 0xcf9);
702 udelay(usec: 50);
703 }
704 reboot_type = BOOT_TRIPLE;
705 break;
706
707 case BOOT_TRIPLE:
708 idt_invalidate();
709 __asm__ __volatile__("int3");
710
711 /* We're probably dead after this, but... */
712 reboot_type = BOOT_KBD;
713 break;
714 }
715 }
716}
717
718void native_machine_shutdown(void)
719{
720 /*
721 * Call enc_kexec_begin() while all CPUs are still active and
722 * interrupts are enabled. This will allow all in-flight memory
723 * conversions to finish cleanly.
724 */
725 if (kexec_in_progress)
726 x86_platform.guest.enc_kexec_begin();
727
728 /* Stop the cpus and apics */
729#ifdef CONFIG_X86_IO_APIC
730 /*
731 * Disabling IO APIC before local APIC is a workaround for
732 * erratum AVR31 in "Intel Atom Processor C2000 Product Family
733 * Specification Update". In this situation, interrupts that target
734 * a Logical Processor whose Local APIC is either in the process of
735 * being hardware disabled or software disabled are neither delivered
736 * nor discarded. When this erratum occurs, the processor may hang.
737 *
738 * Even without the erratum, it still makes sense to quiet IO APIC
739 * before disabling Local APIC.
740 */
741 clear_IO_APIC();
742#endif
743
744#ifdef CONFIG_SMP
745 /*
746 * Stop all of the others. Also disable the local irq to
747 * not receive the per-cpu timer interrupt which may trigger
748 * scheduler's load balance.
749 */
750 local_irq_disable();
751 stop_other_cpus();
752#endif
753
754 lapic_shutdown();
755 restore_boot_irq_mode();
756
757#ifdef CONFIG_HPET_TIMER
758 hpet_disable();
759#endif
760
761#ifdef CONFIG_X86_64
762 x86_platform.iommu_shutdown();
763#endif
764
765 if (kexec_in_progress)
766 x86_platform.guest.enc_kexec_finish();
767}
768
769static void __machine_emergency_restart(int emergency)
770{
771 reboot_emergency = emergency;
772 machine_ops.emergency_restart();
773}
774
775static void native_machine_restart(char *__unused)
776{
777 pr_notice("machine restart\n");
778
779 if (!reboot_force)
780 machine_shutdown();
781 __machine_emergency_restart(emergency: 0);
782}
783
784static void native_machine_halt(void)
785{
786 /* Stop other cpus and apics */
787 machine_shutdown();
788
789 tboot_shutdown(shutdown_type: TB_SHUTDOWN_HALT);
790
791 stop_this_cpu(NULL);
792}
793
794static void native_machine_power_off(void)
795{
796 if (kernel_can_power_off()) {
797 if (!reboot_force)
798 machine_shutdown();
799 do_kernel_power_off();
800 }
801 /* A fallback in case there is no PM info available */
802 tboot_shutdown(shutdown_type: TB_SHUTDOWN_HALT);
803}
804
805struct machine_ops machine_ops __ro_after_init = {
806 .power_off = native_machine_power_off,
807 .shutdown = native_machine_shutdown,
808 .emergency_restart = native_machine_emergency_restart,
809 .restart = native_machine_restart,
810 .halt = native_machine_halt,
811#ifdef CONFIG_CRASH_DUMP
812 .crash_shutdown = native_machine_crash_shutdown,
813#endif
814};
815
816void machine_power_off(void)
817{
818 machine_ops.power_off();
819}
820
821void machine_shutdown(void)
822{
823 machine_ops.shutdown();
824}
825
826void machine_emergency_restart(void)
827{
828 __machine_emergency_restart(emergency: 1);
829}
830
831void machine_restart(char *cmd)
832{
833 machine_ops.restart(cmd);
834}
835
836void machine_halt(void)
837{
838 machine_ops.halt();
839}
840
841#ifdef CONFIG_CRASH_DUMP
842void machine_crash_shutdown(struct pt_regs *regs)
843{
844 machine_ops.crash_shutdown(regs);
845}
846#endif
847
848/* This is the CPU performing the emergency shutdown work. */
849int crashing_cpu = -1;
850
851#if defined(CONFIG_SMP)
852
853static nmi_shootdown_cb shootdown_callback;
854
855static atomic_t waiting_for_crash_ipi;
856static int crash_ipi_issued;
857
858static int crash_nmi_callback(unsigned int val, struct pt_regs *regs)
859{
860 int cpu;
861
862 cpu = raw_smp_processor_id();
863
864 /*
865 * Don't do anything if this handler is invoked on crashing cpu.
866 * Otherwise, system will completely hang. Crashing cpu can get
867 * an NMI if system was initially booted with nmi_watchdog parameter.
868 */
869 if (cpu == crashing_cpu)
870 return NMI_HANDLED;
871 local_irq_disable();
872
873 if (shootdown_callback)
874 shootdown_callback(cpu, regs);
875
876 /*
877 * Prepare the CPU for reboot _after_ invoking the callback so that the
878 * callback can safely use virtualization instructions, e.g. VMCLEAR.
879 */
880 cpu_emergency_disable_virtualization();
881
882 atomic_dec(v: &waiting_for_crash_ipi);
883
884 if (smp_ops.stop_this_cpu) {
885 smp_ops.stop_this_cpu();
886 BUG();
887 }
888
889 /* Assume hlt works */
890 halt();
891 for (;;)
892 cpu_relax();
893
894 return NMI_HANDLED;
895}
896
897/**
898 * nmi_shootdown_cpus - Stop other CPUs via NMI
899 * @callback: Optional callback to be invoked from the NMI handler
900 *
901 * The NMI handler on the remote CPUs invokes @callback, if not
902 * NULL, first and then disables virtualization to ensure that
903 * INIT is recognized during reboot.
904 *
905 * nmi_shootdown_cpus() can only be invoked once. After the first
906 * invocation all other CPUs are stuck in crash_nmi_callback() and
907 * cannot respond to a second NMI.
908 */
909void nmi_shootdown_cpus(nmi_shootdown_cb callback)
910{
911 unsigned long msecs;
912
913 local_irq_disable();
914
915 /*
916 * Avoid certain doom if a shootdown already occurred; re-registering
917 * the NMI handler will cause list corruption, modifying the callback
918 * will do who knows what, etc...
919 */
920 if (WARN_ON_ONCE(crash_ipi_issued))
921 return;
922
923 /* Make a note of crashing cpu. Will be used in NMI callback. */
924 crashing_cpu = smp_processor_id();
925
926 shootdown_callback = callback;
927
928 atomic_set(v: &waiting_for_crash_ipi, i: num_online_cpus() - 1);
929
930 /*
931 * Set emergency handler to preempt other handlers.
932 */
933 set_emergency_nmi_handler(type: NMI_LOCAL, handler: crash_nmi_callback);
934
935 apic_send_IPI_allbutself(NMI_VECTOR);
936
937 /* Kick CPUs looping in NMI context. */
938 WRITE_ONCE(crash_ipi_issued, 1);
939
940 msecs = 1000; /* Wait at most a second for the other cpus to stop */
941 while ((atomic_read(v: &waiting_for_crash_ipi) > 0) && msecs) {
942 mdelay(1);
943 msecs--;
944 }
945
946 /*
947 * Leave the nmi callback set, shootdown is a one-time thing. Clearing
948 * the callback could result in a NULL pointer dereference if a CPU
949 * (finally) responds after the timeout expires.
950 */
951}
952
953static inline void nmi_shootdown_cpus_on_restart(void)
954{
955 if (!crash_ipi_issued)
956 nmi_shootdown_cpus(NULL);
957}
958
959/*
960 * Check if the crash dumping IPI got issued and if so, call its callback
961 * directly. This function is used when we have already been in NMI handler.
962 * It doesn't return.
963 */
964void run_crash_ipi_callback(struct pt_regs *regs)
965{
966 if (crash_ipi_issued)
967 crash_nmi_callback(val: 0, regs);
968}
969
970/* Override the weak function in kernel/panic.c */
971void __noreturn nmi_panic_self_stop(struct pt_regs *regs)
972{
973 while (1) {
974 /* If no CPU is preparing crash dump, we simply loop here. */
975 run_crash_ipi_callback(regs);
976 cpu_relax();
977 }
978}
979
980#else /* !CONFIG_SMP */
981void nmi_shootdown_cpus(nmi_shootdown_cb callback)
982{
983 /* No other CPUs to shoot down */
984}
985
986static inline void nmi_shootdown_cpus_on_restart(void) { }
987
988void run_crash_ipi_callback(struct pt_regs *regs)
989{
990}
991#endif
992

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