// SPDX-License-Identifier: GPL-2.0
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/export.h>
#include <linux/reboot.h>
#include <linux/init.h>
#include <linux/pm.h>
#include <linux/efi.h>
#include <linux/dmi.h>
#include <linux/sched.h>
#include <linux/tboot.h>
#include <linux/delay.h>
#include <linux/objtool.h>
#include <linux/pgtable.h>
#include <linux/kexec.h>
#include <linux/kvm_types.h>
#include <acpi/reboot.h>
#include <asm/io.h>
#include <asm/apic.h>
#include <asm/io_apic.h>
#include <asm/desc.h>
#include <asm/hpet.h>
#include <asm/proto.h>
#include <asm/reboot_fixups.h>
#include <asm/reboot.h>
#include <asm/pci_x86.h>
#include <asm/cpu.h>
#include <asm/nmi.h>
#include <asm/smp.h>

#include <linux/ctype.h>
#include <linux/mc146818rtc.h>
#include <asm/realmode.h>
#include <asm/x86_init.h>
#include <asm/efi.h>

/*
 * Power off function, if any
 */
void (*pm_power_off)(void);
EXPORT_SYMBOL(pm_power_off);

/*
 * This is set if we need to go through the 'emergency' path.
 * When machine_emergency_restart() is called, we may be on
 * an inconsistent state and won't be able to do a clean cleanup
 */
static int reboot_emergency;

/* This is set by the PCI code if either type 1 or type 2 PCI is detected */
bool port_cf9_safe = false;

/*
 * Reboot options and system auto-detection code provided by
 * Dell Inc. so their systems "just work". :-)
 */

/*
 * Some machines require the "reboot=a" commandline options
 */
static int __init set_acpi_reboot(const struct dmi_system_id *d)
{
        if (reboot_type != BOOT_ACPI) {
                reboot_type = BOOT_ACPI;
                pr_info("%s series board detected. Selecting %s-method for reboots.\n",
                        d->ident, "ACPI");
        }
        return 0;
}

/*
 * Some machines require the "reboot=b" or "reboot=k"  commandline options,
 * this quirk makes that automatic.
 */
static int __init set_bios_reboot(const struct dmi_system_id *d)
{
        if (reboot_type != BOOT_BIOS) {
                reboot_type = BOOT_BIOS;
                pr_info("%s series board detected. Selecting %s-method for reboots.\n",
                        d->ident, "BIOS");
        }
        return 0;
}

/*
 * Some machines don't handle the default ACPI reboot method and
 * require the EFI reboot method:
 */
static int __init set_efi_reboot(const struct dmi_system_id *d)
{
        if (reboot_type != BOOT_EFI && !efi_runtime_disabled()) {
                reboot_type = BOOT_EFI;
                pr_info("%s series board detected. Selecting EFI-method for reboot.\n", d->ident);
        }
        return 0;
}

void __noreturn machine_real_restart(unsigned int type)
{
        local_irq_disable();

        /*
         * Write zero to CMOS register number 0x0f, which the BIOS POST
         * routine will recognize as telling it to do a proper reboot.  (Well
         * that's what this book in front of me says -- it may only apply to
         * the Phoenix BIOS though, it's not clear).  At the same time,
         * disable NMIs by setting the top bit in the CMOS address register,
         * as we're about to do peculiar things to the CPU.  I'm not sure if
         * `outb_p' is needed instead of just `outb'.  Use it to be on the
         * safe side.  (Yes, CMOS_WRITE does outb_p's. -  Paul G.)
         */
        spin_lock(&rtc_lock);
        CMOS_WRITE(0x00, 0x8f);
        spin_unlock(&rtc_lock);

        /*
         * Switch to the trampoline page table.
         */
        load_trampoline_pgtable();

        /* Jump to the identity-mapped low memory code */
#ifdef CONFIG_X86_32
        asm volatile("jmpl *%0" : :
                     "rm" (real_mode_header->machine_real_restart_asm),
                     "a" (type));
#else
        asm volatile("ljmpl *%0" : :
                     "m" (real_mode_header->machine_real_restart_asm),
                     "D" (type));
#endif
        unreachable();
}
#ifdef CONFIG_APM_MODULE
EXPORT_SYMBOL(machine_real_restart);
#endif
STACK_FRAME_NON_STANDARD(machine_real_restart);

/*
 * Some Apple MacBook and MacBookPro's needs reboot=p to be able to reboot
 */
static int __init set_pci_reboot(const struct dmi_system_id *d)
{
        if (reboot_type != BOOT_CF9_FORCE) {
                reboot_type = BOOT_CF9_FORCE;
                pr_info("%s series board detected. Selecting %s-method for reboots.\n",
                        d->ident, "PCI");
        }
        return 0;
}

static int __init set_kbd_reboot(const struct dmi_system_id *d)
{
        if (reboot_type != BOOT_KBD) {
                reboot_type = BOOT_KBD;
                pr_info("%s series board detected. Selecting %s-method for reboot.\n",
                        d->ident, "KBD");
        }
        return 0;
}

/*
 * This is a single dmi_table handling all reboot quirks.
 */
static const struct dmi_system_id reboot_dmi_table[] __initconst = {

        /* Acer */
        {       /* Handle reboot issue on Acer Aspire one */
                .callback = set_kbd_reboot,
                .ident = "Acer Aspire One A110",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
                        DMI_MATCH(DMI_PRODUCT_NAME, "AOA110"),
                },
        },
        {       /* Handle reboot issue on Acer TravelMate X514-51T */
                .callback = set_efi_reboot,
                .ident = "Acer TravelMate X514-51T",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
                        DMI_MATCH(DMI_PRODUCT_NAME, "TravelMate X514-51T"),
                },
        },

        /* Apple */
        {       /* Handle problems with rebooting on Apple MacBook5 */
                .callback = set_pci_reboot,
                .ident = "Apple MacBook5",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
                        DMI_MATCH(DMI_PRODUCT_NAME, "MacBook5"),
                },
        },
        {       /* Handle problems with rebooting on Apple MacBook6,1 */
                .callback = set_pci_reboot,
                .ident = "Apple MacBook6,1",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
                        DMI_MATCH(DMI_PRODUCT_NAME, "MacBook6,1"),
                },
        },
        {       /* Handle problems with rebooting on Apple MacBookPro5 */
                .callback = set_pci_reboot,
                .ident = "Apple MacBookPro5",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
                        DMI_MATCH(DMI_PRODUCT_NAME, "MacBookPro5"),
                },
        },
        {       /* Handle problems with rebooting on Apple Macmini3,1 */
                .callback = set_pci_reboot,
                .ident = "Apple Macmini3,1",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
                        DMI_MATCH(DMI_PRODUCT_NAME, "Macmini3,1"),
                },
        },
        {       /* Handle problems with rebooting on the iMac9,1. */
                .callback = set_pci_reboot,
                .ident = "Apple iMac9,1",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
                        DMI_MATCH(DMI_PRODUCT_NAME, "iMac9,1"),
                },
        },
        {       /* Handle problems with rebooting on the iMac10,1. */
                .callback = set_pci_reboot,
                .ident = "Apple iMac10,1",
                .matches = {
                    DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
                    DMI_MATCH(DMI_PRODUCT_NAME, "iMac10,1"),
                },
        },

        /* ASRock */
        {       /* Handle problems with rebooting on ASRock Q1900DC-ITX */
                .callback = set_pci_reboot,
                .ident = "ASRock Q1900DC-ITX",
                .matches = {
                        DMI_MATCH(DMI_BOARD_VENDOR, "ASRock"),
                        DMI_MATCH(DMI_BOARD_NAME, "Q1900DC-ITX"),
                },
        },

        /* ASUS */
        {       /* Handle problems with rebooting on ASUS P4S800 */
                .callback = set_bios_reboot,
                .ident = "ASUS P4S800",
                .matches = {
                        DMI_MATCH(DMI_BOARD_VENDOR, "ASUSTeK Computer INC."),
                        DMI_MATCH(DMI_BOARD_NAME, "P4S800"),
                },
        },
        {       /* Handle problems with rebooting on ASUS EeeBook X205TA */
                .callback = set_acpi_reboot,
                .ident = "ASUS EeeBook X205TA",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
                        DMI_MATCH(DMI_PRODUCT_NAME, "X205TA"),
                },
        },
        {       /* Handle problems with rebooting on ASUS EeeBook X205TAW */
                .callback = set_acpi_reboot,
                .ident = "ASUS EeeBook X205TAW",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
                        DMI_MATCH(DMI_PRODUCT_NAME, "X205TAW"),
                },
        },

        /* Certec */
        {       /* Handle problems with rebooting on Certec BPC600 */
                .callback = set_pci_reboot,
                .ident = "Certec BPC600",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Certec"),
                        DMI_MATCH(DMI_PRODUCT_NAME, "BPC600"),
                },
        },

        /* Dell */
        {       /* Handle problems with rebooting on Dell DXP061 */
                .callback = set_bios_reboot,
                .ident = "Dell DXP061",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
                        DMI_MATCH(DMI_PRODUCT_NAME, "Dell DXP061"),
                },
        },
        {       /* Handle problems with rebooting on Dell E520's */
                .callback = set_bios_reboot,
                .ident = "Dell E520",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
                        DMI_MATCH(DMI_PRODUCT_NAME, "Dell DM061"),
                },
        },
        {       /* Handle problems with rebooting on the Latitude E5410. */
                .callback = set_pci_reboot,
                .ident = "Dell Latitude E5410",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
                        DMI_MATCH(DMI_PRODUCT_NAME, "Latitude E5410"),
                },
        },
        {       /* Handle problems with rebooting on the Latitude E5420. */
                .callback = set_pci_reboot,
                .ident = "Dell Latitude E5420",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
                        DMI_MATCH(DMI_PRODUCT_NAME, "Latitude E5420"),
                },
        },
        {       /* Handle problems with rebooting on the Latitude E6320. */
                .callback = set_pci_reboot,
                .ident = "Dell Latitude E6320",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
                        DMI_MATCH(DMI_PRODUCT_NAME, "Latitude E6320"),
                },
        },
        {       /* Handle problems with rebooting on the Latitude E6420. */
                .callback = set_pci_reboot,
                .ident = "Dell Latitude E6420",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
                        DMI_MATCH(DMI_PRODUCT_NAME, "Latitude E6420"),
                },
        },
        {       /* Handle problems with rebooting on Dell Optiplex 330 with 0KP561 */
                .callback = set_bios_reboot,
                .ident = "Dell OptiPlex 330",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
                        DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 330"),
                        DMI_MATCH(DMI_BOARD_NAME, "0KP561"),
                },
        },
        {       /* Handle problems with rebooting on Dell Optiplex 360 with 0T656F */
                .callback = set_bios_reboot,
                .ident = "Dell OptiPlex 360",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
                        DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 360"),
                        DMI_MATCH(DMI_BOARD_NAME, "0T656F"),
                },
        },
        {       /* Handle problems with rebooting on Dell Optiplex 745's SFF */
                .callback = set_bios_reboot,
                .ident = "Dell OptiPlex 745",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
                        DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 745"),
                },
        },
        {       /* Handle problems with rebooting on Dell Optiplex 745's DFF */
                .callback = set_bios_reboot,
                .ident = "Dell OptiPlex 745",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
                        DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 745"),
                        DMI_MATCH(DMI_BOARD_NAME, "0MM599"),
                },
        },
        {       /* Handle problems with rebooting on Dell Optiplex 745 with 0KW626 */
                .callback = set_bios_reboot,
                .ident = "Dell OptiPlex 745",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
                        DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 745"),
                        DMI_MATCH(DMI_BOARD_NAME, "0KW626"),
                },
        },
        {       /* Handle problems with rebooting on Dell OptiPlex 760 with 0G919G */
                .callback = set_bios_reboot,
                .ident = "Dell OptiPlex 760",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
                        DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 760"),
                        DMI_MATCH(DMI_BOARD_NAME, "0G919G"),
                },
        },
        {       /* Handle problems with rebooting on the OptiPlex 990. */
                .callback = set_pci_reboot,
                .ident = "Dell OptiPlex 990 BIOS A0x",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
                        DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 990"),
                        DMI_MATCH(DMI_BIOS_VERSION, "A0"),
                },
        },
        {       /* Handle problems with rebooting on Dell 300's */
                .callback = set_bios_reboot,
                .ident = "Dell PowerEdge 300",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer Corporation"),
                        DMI_MATCH(DMI_PRODUCT_NAME, "PowerEdge 300/"),
                },
        },
        {       /* Handle problems with rebooting on Dell 1300's */
                .callback = set_bios_reboot,
                .ident = "Dell PowerEdge 1300",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer Corporation"),
                        DMI_MATCH(DMI_PRODUCT_NAME, "PowerEdge 1300/"),
                },
        },
        {       /* Handle problems with rebooting on Dell 2400's */
                .callback = set_bios_reboot,
                .ident = "Dell PowerEdge 2400",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer Corporation"),
                        DMI_MATCH(DMI_PRODUCT_NAME, "PowerEdge 2400"),
                },
        },
        {       /* Handle problems with rebooting on the Dell PowerEdge C6100. */
                .callback = set_pci_reboot,
                .ident = "Dell PowerEdge C6100",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Dell"),
                        DMI_MATCH(DMI_PRODUCT_NAME, "C6100"),
                },
        },
        {       /* Handle problems with rebooting on the Precision M6600. */
                .callback = set_pci_reboot,
                .ident = "Dell Precision M6600",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
                        DMI_MATCH(DMI_PRODUCT_NAME, "Precision M6600"),
                },
        },
        {       /* Handle problems with rebooting on Dell T5400's */
                .callback = set_bios_reboot,
                .ident = "Dell Precision T5400",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
                        DMI_MATCH(DMI_PRODUCT_NAME, "Precision WorkStation T5400"),
                },
        },
        {       /* Handle problems with rebooting on Dell T7400's */
                .callback = set_bios_reboot,
                .ident = "Dell Precision T7400",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
                        DMI_MATCH(DMI_PRODUCT_NAME, "Precision WorkStation T7400"),
                },
        },
        {       /* Handle problems with rebooting on Dell XPS710 */
                .callback = set_bios_reboot,
                .ident = "Dell XPS710",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
                        DMI_MATCH(DMI_PRODUCT_NAME, "Dell XPS710"),
                },
        },
        {       /* Handle problems with rebooting on Dell Optiplex 7450 AIO */
                .callback = set_acpi_reboot,
                .ident = "Dell OptiPlex 7450 AIO",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
                        DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 7450 AIO"),
                },
        },

        /* Hewlett-Packard */
        {       /* Handle problems with rebooting on HP laptops */
                .callback = set_bios_reboot,
                .ident = "HP Compaq Laptop",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
                        DMI_MATCH(DMI_PRODUCT_NAME, "HP Compaq"),
                },
        },

        {       /* PCIe Wifi card isn't detected after reboot otherwise */
                .callback = set_pci_reboot,
                .ident = "Zotac ZBOX CI327 nano",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "NA"),
                        DMI_MATCH(DMI_PRODUCT_NAME, "ZBOX-CI327NANO-GS-01"),
                },
        },

        /* Sony */
        {       /* Handle problems with rebooting on Sony VGN-Z540N */
                .callback = set_bios_reboot,
                .ident = "Sony VGN-Z540N",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Sony Corporation"),
                        DMI_MATCH(DMI_PRODUCT_NAME, "VGN-Z540N"),
                },
        },

        { }
};

static int __init reboot_init(void)
{
        int rv;

        /*
         * Only do the DMI check if reboot_type hasn't been overridden
         * on the command line
         */
        if (!reboot_default)
                return 0;

        /*
         * The DMI quirks table takes precedence. If no quirks entry
         * matches and the ACPI Hardware Reduced bit is set and EFI
         * runtime services are enabled, force EFI reboot.
         */
        rv = dmi_check_system(reboot_dmi_table);

        if (!rv && efi_reboot_required() && !efi_runtime_disabled())
                reboot_type = BOOT_EFI;

        return 0;
}
core_initcall(reboot_init);

static inline void kb_wait(void)
{
        int i;

        for (i = 0; i < 0x10000; i++) {
                if ((inb(0x64) & 0x02) == 0)
                        break;
                udelay(2);
        }
}

static inline void nmi_shootdown_cpus_on_restart(void);

#if IS_ENABLED(CONFIG_KVM_X86)
/* RCU-protected callback to disable virtualization prior to reboot. */
static cpu_emergency_virt_cb __rcu *cpu_emergency_virt_callback;

void cpu_emergency_register_virt_callback(cpu_emergency_virt_cb *callback)
{
        if (WARN_ON_ONCE(rcu_access_pointer(cpu_emergency_virt_callback)))
                return;

        rcu_assign_pointer(cpu_emergency_virt_callback, callback);
}
EXPORT_SYMBOL_FOR_KVM(cpu_emergency_register_virt_callback);

void cpu_emergency_unregister_virt_callback(cpu_emergency_virt_cb *callback)
{
        if (WARN_ON_ONCE(rcu_access_pointer(cpu_emergency_virt_callback) != callback))
                return;

        rcu_assign_pointer(cpu_emergency_virt_callback, NULL);
        synchronize_rcu();
}
EXPORT_SYMBOL_FOR_KVM(cpu_emergency_unregister_virt_callback);

/*
 * Disable virtualization, i.e. VMX or SVM, to ensure INIT is recognized during
 * reboot.  VMX blocks INIT if the CPU is post-VMXON, and SVM blocks INIT if
 * GIF=0, i.e. if the crash occurred between CLGI and STGI.
 */
void cpu_emergency_disable_virtualization(void)
{
        cpu_emergency_virt_cb *callback;

        /*
         * IRQs must be disabled as KVM enables virtualization in hardware via
         * function call IPIs, i.e. IRQs need to be disabled to guarantee
         * virtualization stays disabled.
         */
        lockdep_assert_irqs_disabled();

        rcu_read_lock();
        callback = rcu_dereference(cpu_emergency_virt_callback);
        if (callback)
                callback();
        rcu_read_unlock();
}

static void emergency_reboot_disable_virtualization(void)
{
        local_irq_disable();

        /*
         * Disable virtualization on all CPUs before rebooting to avoid hanging
         * the system, as VMX and SVM block INIT when running in the host.
         *
         * We can't take any locks and we may be on an inconsistent state, so
         * use NMIs as IPIs to tell the other CPUs to disable VMX/SVM and halt.
         *
         * Do the NMI shootdown even if virtualization is off on _this_ CPU, as
         * other CPUs may have virtualization enabled.
         */
        if (rcu_access_pointer(cpu_emergency_virt_callback)) {
                /* Safely force _this_ CPU out of VMX/SVM operation. */
                cpu_emergency_disable_virtualization();

                /* Disable VMX/SVM and halt on other CPUs. */
                nmi_shootdown_cpus_on_restart();
        }
}
#else
static void emergency_reboot_disable_virtualization(void) { }
#endif /* CONFIG_KVM_X86 */

void __attribute__((weak)) mach_reboot_fixups(void)
{
}

/*
 * To the best of our knowledge Windows compatible x86 hardware expects
 * the following on reboot:
 *
 * 1) If the FADT has the ACPI reboot register flag set, try it
 * 2) If still alive, write to the keyboard controller
 * 3) If still alive, write to the ACPI reboot register again
 * 4) If still alive, write to the keyboard controller again
 * 5) If still alive, call the EFI runtime service to reboot
 * 6) If no EFI runtime service, call the BIOS to do a reboot
 *
 * We default to following the same pattern. We also have
 * two other reboot methods: 'triple fault' and 'PCI', which
 * can be triggered via the reboot= kernel boot option or
 * via quirks.
 *
 * This means that this function can never return, it can misbehave
 * by not rebooting properly and hanging.
 */
static void native_machine_emergency_restart(void)
{
        int i;
        int attempt = 0;
        int orig_reboot_type = reboot_type;
        unsigned short mode;

        if (reboot_emergency)
                emergency_reboot_disable_virtualization();

        tboot_shutdown(TB_SHUTDOWN_REBOOT);

        /* Tell the BIOS if we want cold or warm reboot */
        mode = reboot_mode == REBOOT_WARM ? 0x1234 : 0;
        *((unsigned short *)__va(0x472)) = mode;

        /*
         * If an EFI capsule has been registered with the firmware then
         * override the reboot= parameter.
         */
        if (efi_capsule_pending(NULL)) {
                pr_info("EFI capsule is pending, forcing EFI reboot.\n");
                reboot_type = BOOT_EFI;
        }

        for (;;) {
                /* Could also try the reset bit in the Hammer NB */
                switch (reboot_type) {
                case BOOT_ACPI:
                        acpi_reboot();
                        reboot_type = BOOT_KBD;
                        break;

                case BOOT_KBD:
                        mach_reboot_fixups(); /* For board specific fixups */

                        for (i = 0; i < 10; i++) {
                                kb_wait();
                                udelay(50);
                                outb(0xfe, 0x64); /* Pulse reset low */
                                udelay(50);
                        }
                        if (attempt == 0 && orig_reboot_type == BOOT_ACPI) {
                                attempt = 1;
                                reboot_type = BOOT_ACPI;
                        } else {
                                reboot_type = BOOT_EFI;
                        }
                        break;

                case BOOT_EFI:
                        efi_reboot(reboot_mode, NULL);
                        reboot_type = BOOT_BIOS;
                        break;

                case BOOT_BIOS:
                        machine_real_restart(MRR_BIOS);

                        /* We're probably dead after this, but... */
                        reboot_type = BOOT_CF9_SAFE;
                        break;

                case BOOT_CF9_FORCE:
                        port_cf9_safe = true;
                        fallthrough;

                case BOOT_CF9_SAFE:
                        if (port_cf9_safe) {
                                u8 reboot_code = reboot_mode == REBOOT_WARM ?  0x06 : 0x0E;
                                u8 cf9 = inb(0xcf9) & ~reboot_code;
                                outb(cf9|2, 0xcf9); /* Request hard reset */
                                udelay(50);
                                /* Actually do the reset */
                                outb(cf9|reboot_code, 0xcf9);
                                udelay(50);
                        }
                        reboot_type = BOOT_TRIPLE;
                        break;

                case BOOT_TRIPLE:
                        idt_invalidate();
                        __asm__ __volatile__("int3");

                        /* We're probably dead after this, but... */
                        reboot_type = BOOT_KBD;
                        break;
                }
        }
}

void native_machine_shutdown(void)
{
        /*
         * Call enc_kexec_begin() while all CPUs are still active and
         * interrupts are enabled. This will allow all in-flight memory
         * conversions to finish cleanly.
         */
        if (kexec_in_progress)
                x86_platform.guest.enc_kexec_begin();

        /* Stop the cpus and apics */
#ifdef CONFIG_X86_IO_APIC
        /*
         * Disabling IO APIC before local APIC is a workaround for
         * erratum AVR31 in "Intel Atom Processor C2000 Product Family
         * Specification Update". In this situation, interrupts that target
         * a Logical Processor whose Local APIC is either in the process of
         * being hardware disabled or software disabled are neither delivered
         * nor discarded. When this erratum occurs, the processor may hang.
         *
         * Even without the erratum, it still makes sense to quiet IO APIC
         * before disabling Local APIC.
         */
        clear_IO_APIC();
#endif

#ifdef CONFIG_SMP
        /*
         * Stop all of the others. Also disable the local irq to
         * not receive the per-cpu timer interrupt which may trigger
         * scheduler's load balance.
         */
        local_irq_disable();
        stop_other_cpus();
#endif

        lapic_shutdown();
        restore_boot_irq_mode();

#ifdef CONFIG_HPET_TIMER
        hpet_disable();
#endif

#ifdef CONFIG_X86_64
        x86_platform.iommu_shutdown();
#endif

        if (kexec_in_progress)
                x86_platform.guest.enc_kexec_finish();
}

static void __machine_emergency_restart(int emergency)
{
        reboot_emergency = emergency;
        machine_ops.emergency_restart();
}

static void native_machine_restart(char *__unused)
{
        pr_notice("machine restart\n");

        if (!reboot_force)
                machine_shutdown();
        __machine_emergency_restart(0);
}

static void native_machine_halt(void)
{
        /* Stop other cpus and apics */
        machine_shutdown();

        tboot_shutdown(TB_SHUTDOWN_HALT);

        stop_this_cpu(NULL);
}

static void native_machine_power_off(void)
{
        if (kernel_can_power_off()) {
                if (!reboot_force)
                        machine_shutdown();
                do_kernel_power_off();
        }
        /* A fallback in case there is no PM info available */
        tboot_shutdown(TB_SHUTDOWN_HALT);
}

struct machine_ops machine_ops __ro_after_init = {
        .power_off = native_machine_power_off,
        .shutdown = native_machine_shutdown,
        .emergency_restart = native_machine_emergency_restart,
        .restart = native_machine_restart,
        .halt = native_machine_halt,
#ifdef CONFIG_CRASH_DUMP
        .crash_shutdown = native_machine_crash_shutdown,
#endif
};

void machine_power_off(void)
{
        machine_ops.power_off();
}

void machine_shutdown(void)
{
        machine_ops.shutdown();
}

void machine_emergency_restart(void)
{
        __machine_emergency_restart(1);
}

void machine_restart(char *cmd)
{
        machine_ops.restart(cmd);
}

void machine_halt(void)
{
        machine_ops.halt();
}

#ifdef CONFIG_CRASH_DUMP
void machine_crash_shutdown(struct pt_regs *regs)
{
        machine_ops.crash_shutdown(regs);
}
#endif

/* This is the CPU performing the emergency shutdown work. */
int crashing_cpu = -1;

#if defined(CONFIG_SMP)

static nmi_shootdown_cb shootdown_callback;

static atomic_t waiting_for_crash_ipi;
static int crash_ipi_issued;

static int crash_nmi_callback(unsigned int val, struct pt_regs *regs)
{
        int cpu;

        cpu = raw_smp_processor_id();

        /*
         * Don't do anything if this handler is invoked on crashing cpu.
         * Otherwise, system will completely hang. Crashing cpu can get
         * an NMI if system was initially booted with nmi_watchdog parameter.
         */
        if (cpu == crashing_cpu)
                return NMI_HANDLED;
        local_irq_disable();

        if (shootdown_callback)
                shootdown_callback(cpu, regs);

        /*
         * Prepare the CPU for reboot _after_ invoking the callback so that the
         * callback can safely use virtualization instructions, e.g. VMCLEAR.
         */
        cpu_emergency_disable_virtualization();

        atomic_dec(&waiting_for_crash_ipi);

        if (smp_ops.stop_this_cpu) {
                smp_ops.stop_this_cpu();
                BUG();
        }

        /* Assume hlt works */
        halt();
        for (;;)
                cpu_relax();

        return NMI_HANDLED;
}

/**
 * nmi_shootdown_cpus - Stop other CPUs via NMI
 * @callback:   Optional callback to be invoked from the NMI handler
 *
 * The NMI handler on the remote CPUs invokes @callback, if not
 * NULL, first and then disables virtualization to ensure that
 * INIT is recognized during reboot.
 *
 * nmi_shootdown_cpus() can only be invoked once. After the first
 * invocation all other CPUs are stuck in crash_nmi_callback() and
 * cannot respond to a second NMI.
 */
void nmi_shootdown_cpus(nmi_shootdown_cb callback)
{
        unsigned long msecs;

        local_irq_disable();

        /*
         * Avoid certain doom if a shootdown already occurred; re-registering
         * the NMI handler will cause list corruption, modifying the callback
         * will do who knows what, etc...
         */
        if (WARN_ON_ONCE(crash_ipi_issued))
                return;

        /* Make a note of crashing cpu. Will be used in NMI callback. */
        crashing_cpu = smp_processor_id();

        shootdown_callback = callback;

        atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1);

        /*
         * Set emergency handler to preempt other handlers.
         */
        set_emergency_nmi_handler(NMI_LOCAL, crash_nmi_callback);

        apic_send_IPI_allbutself(NMI_VECTOR);

        /* Kick CPUs looping in NMI context. */
        WRITE_ONCE(crash_ipi_issued, 1);

        msecs = 1000; /* Wait at most a second for the other cpus to stop */
        while ((atomic_read(&waiting_for_crash_ipi) > 0) && msecs) {
                mdelay(1);
                msecs--;
        }

        /*
         * Leave the nmi callback set, shootdown is a one-time thing.  Clearing
         * the callback could result in a NULL pointer dereference if a CPU
         * (finally) responds after the timeout expires.
         */
}

static inline void nmi_shootdown_cpus_on_restart(void)
{
        if (!crash_ipi_issued)
                nmi_shootdown_cpus(NULL);
}

/*
 * Check if the crash dumping IPI got issued and if so, call its callback
 * directly. This function is used when we have already been in NMI handler.
 * It doesn't return.
 */
void run_crash_ipi_callback(struct pt_regs *regs)
{
        if (crash_ipi_issued)
                crash_nmi_callback(0, regs);
}

/* Override the weak function in kernel/panic.c */
void __noreturn nmi_panic_self_stop(struct pt_regs *regs)
{
        while (1) {
                /* If no CPU is preparing crash dump, we simply loop here. */
                run_crash_ipi_callback(regs);
                cpu_relax();
        }
}

#else /* !CONFIG_SMP */
void nmi_shootdown_cpus(nmi_shootdown_cb callback)
{
        /* No other CPUs to shoot down */
}

static inline void nmi_shootdown_cpus_on_restart(void) { }

void run_crash_ipi_callback(struct pt_regs *regs)
{
}
#endif