1 // SPDX-License-Identifier: GPL-2.0
2 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
4 #include <linux/export.h>
5 #include <linux/reboot.h>
6 #include <linux/init.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 <acpi/reboot.h>
18 #include <asm/io_apic.h>
21 #include <asm/proto.h>
22 #include <asm/reboot_fixups.h>
23 #include <asm/reboot.h>
24 #include <asm/pci_x86.h>
25 #include <asm/virtext.h>
30 #include <linux/ctype.h>
31 #include <linux/mc146818rtc.h>
32 #include <asm/realmode.h>
33 #include <asm/x86_init.h>
37 * Power off function, if any
39 void (*pm_power_off)(void);
40 EXPORT_SYMBOL(pm_power_off);
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
47 static int reboot_emergency;
49 /* This is set by the PCI code if either type 1 or type 2 PCI is detected */
50 bool port_cf9_safe = false;
53 * Reboot options and system auto-detection code provided by
54 * Dell Inc. so their systems "just work". :-)
58 * Some machines require the "reboot=a" commandline options
60 static int __init set_acpi_reboot(const struct dmi_system_id *d)
62 if (reboot_type != BOOT_ACPI) {
63 reboot_type = BOOT_ACPI;
64 pr_info("%s series board detected. Selecting %s-method for reboots.\n",
71 * Some machines require the "reboot=b" or "reboot=k" commandline options,
72 * this quirk makes that automatic.
74 static int __init set_bios_reboot(const struct dmi_system_id *d)
76 if (reboot_type != BOOT_BIOS) {
77 reboot_type = BOOT_BIOS;
78 pr_info("%s series board detected. Selecting %s-method for reboots.\n",
85 * Some machines don't handle the default ACPI reboot method and
86 * require the EFI reboot method:
88 static int __init set_efi_reboot(const struct dmi_system_id *d)
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);
97 void __noreturn machine_real_restart(unsigned int type)
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.)
111 spin_lock(&rtc_lock);
112 CMOS_WRITE(0x00, 0x8f);
113 spin_unlock(&rtc_lock);
116 * Switch to the trampoline page table.
118 load_trampoline_pgtable();
120 /* Jump to the identity-mapped low memory code */
122 asm volatile("jmpl *%0" : :
123 "rm" (real_mode_header->machine_real_restart_asm),
126 asm volatile("ljmpl *%0" : :
127 "m" (real_mode_header->machine_real_restart_asm),
132 #ifdef CONFIG_APM_MODULE
133 EXPORT_SYMBOL(machine_real_restart);
135 STACK_FRAME_NON_STANDARD(machine_real_restart);
138 * Some Apple MacBook and MacBookPro's needs reboot=p to be able to reboot
140 static int __init set_pci_reboot(const struct dmi_system_id *d)
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",
150 static int __init set_kbd_reboot(const struct dmi_system_id *d)
152 if (reboot_type != BOOT_KBD) {
153 reboot_type = BOOT_KBD;
154 pr_info("%s series board detected. Selecting %s-method for reboot.\n",
161 * This is a single dmi_table handling all reboot quirks.
163 static const struct dmi_system_id reboot_dmi_table[] __initconst = {
166 { /* Handle reboot issue on Acer Aspire one */
167 .callback = set_kbd_reboot,
168 .ident = "Acer Aspire One A110",
170 DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
171 DMI_MATCH(DMI_PRODUCT_NAME, "AOA110"),
174 { /* Handle reboot issue on Acer TravelMate X514-51T */
175 .callback = set_efi_reboot,
176 .ident = "Acer TravelMate X514-51T",
178 DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
179 DMI_MATCH(DMI_PRODUCT_NAME, "TravelMate X514-51T"),
184 { /* Handle problems with rebooting on Apple MacBook5 */
185 .callback = set_pci_reboot,
186 .ident = "Apple MacBook5",
188 DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
189 DMI_MATCH(DMI_PRODUCT_NAME, "MacBook5"),
192 { /* Handle problems with rebooting on Apple MacBook6,1 */
193 .callback = set_pci_reboot,
194 .ident = "Apple MacBook6,1",
196 DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
197 DMI_MATCH(DMI_PRODUCT_NAME, "MacBook6,1"),
200 { /* Handle problems with rebooting on Apple MacBookPro5 */
201 .callback = set_pci_reboot,
202 .ident = "Apple MacBookPro5",
204 DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
205 DMI_MATCH(DMI_PRODUCT_NAME, "MacBookPro5"),
208 { /* Handle problems with rebooting on Apple Macmini3,1 */
209 .callback = set_pci_reboot,
210 .ident = "Apple Macmini3,1",
212 DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
213 DMI_MATCH(DMI_PRODUCT_NAME, "Macmini3,1"),
216 { /* Handle problems with rebooting on the iMac9,1. */
217 .callback = set_pci_reboot,
218 .ident = "Apple iMac9,1",
220 DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
221 DMI_MATCH(DMI_PRODUCT_NAME, "iMac9,1"),
224 { /* Handle problems with rebooting on the iMac10,1. */
225 .callback = set_pci_reboot,
226 .ident = "Apple iMac10,1",
228 DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
229 DMI_MATCH(DMI_PRODUCT_NAME, "iMac10,1"),
234 { /* Handle problems with rebooting on ASRock Q1900DC-ITX */
235 .callback = set_pci_reboot,
236 .ident = "ASRock Q1900DC-ITX",
238 DMI_MATCH(DMI_BOARD_VENDOR, "ASRock"),
239 DMI_MATCH(DMI_BOARD_NAME, "Q1900DC-ITX"),
244 { /* Handle problems with rebooting on ASUS P4S800 */
245 .callback = set_bios_reboot,
246 .ident = "ASUS P4S800",
248 DMI_MATCH(DMI_BOARD_VENDOR, "ASUSTeK Computer INC."),
249 DMI_MATCH(DMI_BOARD_NAME, "P4S800"),
252 { /* Handle problems with rebooting on ASUS EeeBook X205TA */
253 .callback = set_acpi_reboot,
254 .ident = "ASUS EeeBook X205TA",
256 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
257 DMI_MATCH(DMI_PRODUCT_NAME, "X205TA"),
260 { /* Handle problems with rebooting on ASUS EeeBook X205TAW */
261 .callback = set_acpi_reboot,
262 .ident = "ASUS EeeBook X205TAW",
264 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
265 DMI_MATCH(DMI_PRODUCT_NAME, "X205TAW"),
270 { /* Handle problems with rebooting on Certec BPC600 */
271 .callback = set_pci_reboot,
272 .ident = "Certec BPC600",
274 DMI_MATCH(DMI_SYS_VENDOR, "Certec"),
275 DMI_MATCH(DMI_PRODUCT_NAME, "BPC600"),
280 { /* Handle problems with rebooting on Dell DXP061 */
281 .callback = set_bios_reboot,
282 .ident = "Dell DXP061",
284 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
285 DMI_MATCH(DMI_PRODUCT_NAME, "Dell DXP061"),
288 { /* Handle problems with rebooting on Dell E520's */
289 .callback = set_bios_reboot,
290 .ident = "Dell E520",
292 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
293 DMI_MATCH(DMI_PRODUCT_NAME, "Dell DM061"),
296 { /* Handle problems with rebooting on the Latitude E5410. */
297 .callback = set_pci_reboot,
298 .ident = "Dell Latitude E5410",
300 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
301 DMI_MATCH(DMI_PRODUCT_NAME, "Latitude E5410"),
304 { /* Handle problems with rebooting on the Latitude E5420. */
305 .callback = set_pci_reboot,
306 .ident = "Dell Latitude E5420",
308 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
309 DMI_MATCH(DMI_PRODUCT_NAME, "Latitude E5420"),
312 { /* Handle problems with rebooting on the Latitude E6320. */
313 .callback = set_pci_reboot,
314 .ident = "Dell Latitude E6320",
316 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
317 DMI_MATCH(DMI_PRODUCT_NAME, "Latitude E6320"),
320 { /* Handle problems with rebooting on the Latitude E6420. */
321 .callback = set_pci_reboot,
322 .ident = "Dell Latitude E6420",
324 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
325 DMI_MATCH(DMI_PRODUCT_NAME, "Latitude E6420"),
328 { /* Handle problems with rebooting on Dell Optiplex 330 with 0KP561 */
329 .callback = set_bios_reboot,
330 .ident = "Dell OptiPlex 330",
332 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
333 DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 330"),
334 DMI_MATCH(DMI_BOARD_NAME, "0KP561"),
337 { /* Handle problems with rebooting on Dell Optiplex 360 with 0T656F */
338 .callback = set_bios_reboot,
339 .ident = "Dell OptiPlex 360",
341 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
342 DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 360"),
343 DMI_MATCH(DMI_BOARD_NAME, "0T656F"),
346 { /* Handle problems with rebooting on Dell Optiplex 745's SFF */
347 .callback = set_bios_reboot,
348 .ident = "Dell OptiPlex 745",
350 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
351 DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 745"),
354 { /* Handle problems with rebooting on Dell Optiplex 745's DFF */
355 .callback = set_bios_reboot,
356 .ident = "Dell OptiPlex 745",
358 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
359 DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 745"),
360 DMI_MATCH(DMI_BOARD_NAME, "0MM599"),
363 { /* Handle problems with rebooting on Dell Optiplex 745 with 0KW626 */
364 .callback = set_bios_reboot,
365 .ident = "Dell OptiPlex 745",
367 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
368 DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 745"),
369 DMI_MATCH(DMI_BOARD_NAME, "0KW626"),
372 { /* Handle problems with rebooting on Dell OptiPlex 760 with 0G919G */
373 .callback = set_bios_reboot,
374 .ident = "Dell OptiPlex 760",
376 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
377 DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 760"),
378 DMI_MATCH(DMI_BOARD_NAME, "0G919G"),
381 { /* Handle problems with rebooting on the OptiPlex 990. */
382 .callback = set_pci_reboot,
383 .ident = "Dell OptiPlex 990 BIOS A0x",
385 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
386 DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 990"),
387 DMI_MATCH(DMI_BIOS_VERSION, "A0"),
390 { /* Handle problems with rebooting on Dell 300's */
391 .callback = set_bios_reboot,
392 .ident = "Dell PowerEdge 300",
394 DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer Corporation"),
395 DMI_MATCH(DMI_PRODUCT_NAME, "PowerEdge 300/"),
398 { /* Handle problems with rebooting on Dell 1300's */
399 .callback = set_bios_reboot,
400 .ident = "Dell PowerEdge 1300",
402 DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer Corporation"),
403 DMI_MATCH(DMI_PRODUCT_NAME, "PowerEdge 1300/"),
406 { /* Handle problems with rebooting on Dell 2400's */
407 .callback = set_bios_reboot,
408 .ident = "Dell PowerEdge 2400",
410 DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer Corporation"),
411 DMI_MATCH(DMI_PRODUCT_NAME, "PowerEdge 2400"),
414 { /* Handle problems with rebooting on the Dell PowerEdge C6100. */
415 .callback = set_pci_reboot,
416 .ident = "Dell PowerEdge C6100",
418 DMI_MATCH(DMI_SYS_VENDOR, "Dell"),
419 DMI_MATCH(DMI_PRODUCT_NAME, "C6100"),
422 { /* Handle problems with rebooting on the Precision M6600. */
423 .callback = set_pci_reboot,
424 .ident = "Dell Precision M6600",
426 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
427 DMI_MATCH(DMI_PRODUCT_NAME, "Precision M6600"),
430 { /* Handle problems with rebooting on Dell T5400's */
431 .callback = set_bios_reboot,
432 .ident = "Dell Precision T5400",
434 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
435 DMI_MATCH(DMI_PRODUCT_NAME, "Precision WorkStation T5400"),
438 { /* Handle problems with rebooting on Dell T7400's */
439 .callback = set_bios_reboot,
440 .ident = "Dell Precision T7400",
442 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
443 DMI_MATCH(DMI_PRODUCT_NAME, "Precision WorkStation T7400"),
446 { /* Handle problems with rebooting on Dell XPS710 */
447 .callback = set_bios_reboot,
448 .ident = "Dell XPS710",
450 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
451 DMI_MATCH(DMI_PRODUCT_NAME, "Dell XPS710"),
454 { /* Handle problems with rebooting on Dell Optiplex 7450 AIO */
455 .callback = set_acpi_reboot,
456 .ident = "Dell OptiPlex 7450 AIO",
458 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
459 DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 7450 AIO"),
463 /* Hewlett-Packard */
464 { /* Handle problems with rebooting on HP laptops */
465 .callback = set_bios_reboot,
466 .ident = "HP Compaq Laptop",
468 DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
469 DMI_MATCH(DMI_PRODUCT_NAME, "HP Compaq"),
473 { /* PCIe Wifi card isn't detected after reboot otherwise */
474 .callback = set_pci_reboot,
475 .ident = "Zotac ZBOX CI327 nano",
477 DMI_MATCH(DMI_SYS_VENDOR, "NA"),
478 DMI_MATCH(DMI_PRODUCT_NAME, "ZBOX-CI327NANO-GS-01"),
483 { /* Handle problems with rebooting on Sony VGN-Z540N */
484 .callback = set_bios_reboot,
485 .ident = "Sony VGN-Z540N",
487 DMI_MATCH(DMI_SYS_VENDOR, "Sony Corporation"),
488 DMI_MATCH(DMI_PRODUCT_NAME, "VGN-Z540N"),
495 static int __init reboot_init(void)
500 * Only do the DMI check if reboot_type hasn't been overridden
501 * on the command line
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.
511 rv = dmi_check_system(reboot_dmi_table);
513 if (!rv && efi_reboot_required() && !efi_runtime_disabled())
514 reboot_type = BOOT_EFI;
518 core_initcall(reboot_init);
520 static inline void kb_wait(void)
524 for (i = 0; i < 0x10000; i++) {
525 if ((inb(0x64) & 0x02) == 0)
531 static inline void nmi_shootdown_cpus_on_restart(void);
533 static void emergency_reboot_disable_virtualization(void)
535 /* Just make sure we won't change CPUs while doing this */
539 * Disable virtualization on all CPUs before rebooting to avoid hanging
540 * the system, as VMX and SVM block INIT when running in the host.
542 * We can't take any locks and we may be on an inconsistent state, so
543 * use NMIs as IPIs to tell the other CPUs to disable VMX/SVM and halt.
545 * Do the NMI shootdown even if virtualization is off on _this_ CPU, as
546 * other CPUs may have virtualization enabled.
548 if (cpu_has_vmx() || cpu_has_svm(NULL)) {
549 /* Safely force _this_ CPU out of VMX/SVM operation. */
550 cpu_emergency_disable_virtualization();
552 /* Disable VMX/SVM and halt on other CPUs. */
553 nmi_shootdown_cpus_on_restart();
558 void __attribute__((weak)) mach_reboot_fixups(void)
563 * To the best of our knowledge Windows compatible x86 hardware expects
564 * the following on reboot:
566 * 1) If the FADT has the ACPI reboot register flag set, try it
567 * 2) If still alive, write to the keyboard controller
568 * 3) If still alive, write to the ACPI reboot register again
569 * 4) If still alive, write to the keyboard controller again
570 * 5) If still alive, call the EFI runtime service to reboot
571 * 6) If no EFI runtime service, call the BIOS to do a reboot
573 * We default to following the same pattern. We also have
574 * two other reboot methods: 'triple fault' and 'PCI', which
575 * can be triggered via the reboot= kernel boot option or
578 * This means that this function can never return, it can misbehave
579 * by not rebooting properly and hanging.
581 static void native_machine_emergency_restart(void)
585 int orig_reboot_type = reboot_type;
588 if (reboot_emergency)
589 emergency_reboot_disable_virtualization();
591 tboot_shutdown(TB_SHUTDOWN_REBOOT);
593 /* Tell the BIOS if we want cold or warm reboot */
594 mode = reboot_mode == REBOOT_WARM ? 0x1234 : 0;
595 *((unsigned short *)__va(0x472)) = mode;
598 * If an EFI capsule has been registered with the firmware then
599 * override the reboot= parameter.
601 if (efi_capsule_pending(NULL)) {
602 pr_info("EFI capsule is pending, forcing EFI reboot.\n");
603 reboot_type = BOOT_EFI;
607 /* Could also try the reset bit in the Hammer NB */
608 switch (reboot_type) {
611 reboot_type = BOOT_KBD;
615 mach_reboot_fixups(); /* For board specific fixups */
617 for (i = 0; i < 10; i++) {
620 outb(0xfe, 0x64); /* Pulse reset low */
623 if (attempt == 0 && orig_reboot_type == BOOT_ACPI) {
625 reboot_type = BOOT_ACPI;
627 reboot_type = BOOT_EFI;
632 efi_reboot(reboot_mode, NULL);
633 reboot_type = BOOT_BIOS;
637 machine_real_restart(MRR_BIOS);
639 /* We're probably dead after this, but... */
640 reboot_type = BOOT_CF9_SAFE;
644 port_cf9_safe = true;
649 u8 reboot_code = reboot_mode == REBOOT_WARM ? 0x06 : 0x0E;
650 u8 cf9 = inb(0xcf9) & ~reboot_code;
651 outb(cf9|2, 0xcf9); /* Request hard reset */
653 /* Actually do the reset */
654 outb(cf9|reboot_code, 0xcf9);
657 reboot_type = BOOT_TRIPLE;
661 idt_invalidate(NULL);
662 __asm__ __volatile__("int3");
664 /* We're probably dead after this, but... */
665 reboot_type = BOOT_KBD;
671 void native_machine_shutdown(void)
673 /* Stop the cpus and apics */
674 #ifdef CONFIG_X86_IO_APIC
676 * Disabling IO APIC before local APIC is a workaround for
677 * erratum AVR31 in "Intel Atom Processor C2000 Product Family
678 * Specification Update". In this situation, interrupts that target
679 * a Logical Processor whose Local APIC is either in the process of
680 * being hardware disabled or software disabled are neither delivered
681 * nor discarded. When this erratum occurs, the processor may hang.
683 * Even without the erratum, it still makes sense to quiet IO APIC
684 * before disabling Local APIC.
691 * Stop all of the others. Also disable the local irq to
692 * not receive the per-cpu timer interrupt which may trigger
693 * scheduler's load balance.
700 restore_boot_irq_mode();
702 #ifdef CONFIG_HPET_TIMER
707 x86_platform.iommu_shutdown();
711 static void __machine_emergency_restart(int emergency)
713 reboot_emergency = emergency;
714 machine_ops.emergency_restart();
717 static void native_machine_restart(char *__unused)
719 pr_notice("machine restart\n");
723 __machine_emergency_restart(0);
726 static void native_machine_halt(void)
728 /* Stop other cpus and apics */
731 tboot_shutdown(TB_SHUTDOWN_HALT);
736 static void native_machine_power_off(void)
743 /* A fallback in case there is no PM info available */
744 tboot_shutdown(TB_SHUTDOWN_HALT);
747 struct machine_ops machine_ops __ro_after_init = {
748 .power_off = native_machine_power_off,
749 .shutdown = native_machine_shutdown,
750 .emergency_restart = native_machine_emergency_restart,
751 .restart = native_machine_restart,
752 .halt = native_machine_halt,
753 #ifdef CONFIG_KEXEC_CORE
754 .crash_shutdown = native_machine_crash_shutdown,
758 void machine_power_off(void)
760 machine_ops.power_off();
763 void machine_shutdown(void)
765 machine_ops.shutdown();
768 void machine_emergency_restart(void)
770 __machine_emergency_restart(1);
773 void machine_restart(char *cmd)
775 machine_ops.restart(cmd);
778 void machine_halt(void)
783 #ifdef CONFIG_KEXEC_CORE
784 void machine_crash_shutdown(struct pt_regs *regs)
786 machine_ops.crash_shutdown(regs);
791 /* This is the CPU performing the emergency shutdown work. */
792 int crashing_cpu = -1;
795 * Disable virtualization, i.e. VMX or SVM, to ensure INIT is recognized during
796 * reboot. VMX blocks INIT if the CPU is post-VMXON, and SVM blocks INIT if
797 * GIF=0, i.e. if the crash occurred between CLGI and STGI.
799 void cpu_emergency_disable_virtualization(void)
801 cpu_emergency_vmxoff();
802 cpu_emergency_svm_disable();
805 #if defined(CONFIG_SMP)
807 static nmi_shootdown_cb shootdown_callback;
809 static atomic_t waiting_for_crash_ipi;
810 static int crash_ipi_issued;
812 static int crash_nmi_callback(unsigned int val, struct pt_regs *regs)
816 cpu = raw_smp_processor_id();
819 * Don't do anything if this handler is invoked on crashing cpu.
820 * Otherwise, system will completely hang. Crashing cpu can get
821 * an NMI if system was initially booted with nmi_watchdog parameter.
823 if (cpu == crashing_cpu)
827 if (shootdown_callback)
828 shootdown_callback(cpu, regs);
831 * Prepare the CPU for reboot _after_ invoking the callback so that the
832 * callback can safely use virtualization instructions, e.g. VMCLEAR.
834 cpu_emergency_disable_virtualization();
836 atomic_dec(&waiting_for_crash_ipi);
837 /* Assume hlt works */
846 * nmi_shootdown_cpus - Stop other CPUs via NMI
847 * @callback: Optional callback to be invoked from the NMI handler
849 * The NMI handler on the remote CPUs invokes @callback, if not
850 * NULL, first and then disables virtualization to ensure that
851 * INIT is recognized during reboot.
853 * nmi_shootdown_cpus() can only be invoked once. After the first
854 * invocation all other CPUs are stuck in crash_nmi_callback() and
855 * cannot respond to a second NMI.
857 void nmi_shootdown_cpus(nmi_shootdown_cb callback)
864 * Avoid certain doom if a shootdown already occurred; re-registering
865 * the NMI handler will cause list corruption, modifying the callback
866 * will do who knows what, etc...
868 if (WARN_ON_ONCE(crash_ipi_issued))
871 /* Make a note of crashing cpu. Will be used in NMI callback. */
872 crashing_cpu = safe_smp_processor_id();
874 shootdown_callback = callback;
876 atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1);
877 /* Would it be better to replace the trap vector here? */
878 if (register_nmi_handler(NMI_LOCAL, crash_nmi_callback,
879 NMI_FLAG_FIRST, "crash"))
880 return; /* Return what? */
882 * Ensure the new callback function is set before sending
887 apic_send_IPI_allbutself(NMI_VECTOR);
889 /* Kick CPUs looping in NMI context. */
890 WRITE_ONCE(crash_ipi_issued, 1);
892 msecs = 1000; /* Wait at most a second for the other cpus to stop */
893 while ((atomic_read(&waiting_for_crash_ipi) > 0) && msecs) {
899 * Leave the nmi callback set, shootdown is a one-time thing. Clearing
900 * the callback could result in a NULL pointer dereference if a CPU
901 * (finally) responds after the timeout expires.
905 static inline void nmi_shootdown_cpus_on_restart(void)
907 if (!crash_ipi_issued)
908 nmi_shootdown_cpus(NULL);
912 * Check if the crash dumping IPI got issued and if so, call its callback
913 * directly. This function is used when we have already been in NMI handler.
916 void run_crash_ipi_callback(struct pt_regs *regs)
918 if (crash_ipi_issued)
919 crash_nmi_callback(0, regs);
922 /* Override the weak function in kernel/panic.c */
923 void nmi_panic_self_stop(struct pt_regs *regs)
926 /* If no CPU is preparing crash dump, we simply loop here. */
927 run_crash_ipi_callback(regs);
932 #else /* !CONFIG_SMP */
933 void nmi_shootdown_cpus(nmi_shootdown_cb callback)
935 /* No other CPUs to shoot down */
938 static inline void nmi_shootdown_cpus_on_restart(void) { }
940 void run_crash_ipi_callback(struct pt_regs *regs)