void __init efi_runtime_update_mappings(void)
{
	efi_memory_desc_t *md;

	if (efi_enabled(EFI_OLD_MEMMAP)) {
		if (__supported_pte_mask & _PAGE_NX)
			runtime_code_page_mkexec();
		return;
	}

	/*
	 * Use the EFI Memory Attribute Table for mapping permissions if it
	 * exists, since it is intended to supersede EFI_PROPERTIES_TABLE.
	 */
	if (efi_enabled(EFI_MEM_ATTR)) {
		efi_memattr_apply_permissions(NULL, efi_update_mem_attr);
		return;
	}

	/*
	 * EFI_MEMORY_ATTRIBUTES_TABLE is intended to replace
	 * EFI_PROPERTIES_TABLE. So, use EFI_PROPERTIES_TABLE to update
	 * permissions only if EFI_MEMORY_ATTRIBUTES_TABLE is not
	 * published by the firmware. Even if we find a buggy implementation of
	 * EFI_MEMORY_ATTRIBUTES_TABLE, don't fall back to
	 * EFI_PROPERTIES_TABLE, because of the same reason.
	 */

	if (!efi_enabled(EFI_NX_PE_DATA))
		return;

	for_each_efi_memory_desc(md) {
		unsigned long pf = 0;

		if (!(md->attribute & EFI_MEMORY_RUNTIME))
			continue;

		if (!(md->attribute & EFI_MEMORY_WB))
			pf |= _PAGE_PCD;

		if ((md->attribute & EFI_MEMORY_XP) ||
			(md->type == EFI_RUNTIME_SERVICES_DATA))
			pf |= _PAGE_NX;

		if (!(md->attribute & EFI_MEMORY_RO) &&
			(md->type != EFI_RUNTIME_SERVICES_CODE))
			pf |= _PAGE_RW;

		if (sev_active())
			pf |= _PAGE_ENC;

		efi_update_mappings(md, pf);
	}
}

/*
 * To be called after the EFI page tables have been populated. If a memory
 * attributes table is available, its contents will be used to update the
 * mappings with tightened permissions as described by the table.
 * This requires the UEFI memory map to have already been populated with
 * virtual addresses.
 */
int __init efi_memattr_apply_permissions(struct mm_struct *mm,
					 efi_memattr_perm_setter fn)
{
	efi_memory_attributes_table_t *tbl;
	int i, ret;

	if (tbl_size <= sizeof(*tbl))
		return 0;

	/*
	 * We need the EFI memory map to be setup so we can use it to
	 * lookup the virtual addresses of all entries in the  of EFI
	 * Memory Attributes table. If it isn't available, this
	 * function should not be called.
	 */
	if (WARN_ON(!efi_enabled(EFI_MEMMAP)))
		return 0;

	tbl = memremap(efi.mem_attr_table, tbl_size, MEMREMAP_WB);
	if (!tbl) {
		pr_err("Failed to map EFI Memory Attributes table @ 0x%lx\n",
		       efi.mem_attr_table);
		return -ENOMEM;
	}

	if (efi_enabled(EFI_DBG))
		pr_info("Processing EFI Memory Attributes table:\n");

	for (i = ret = 0; ret == 0 && i < tbl->num_entries; i++) {
		efi_memory_desc_t md;
		unsigned long size;
		bool valid;
		char buf[64];

		valid = entry_is_valid((void *)tbl->entry + i * tbl->desc_size,
				       &md);
		size = md.num_pages << EFI_PAGE_SHIFT;
		if (efi_enabled(EFI_DBG) || !valid)
			pr_info("%s 0x%012llx-0x%012llx %s\n",
				valid ? "" : "!", md.phys_addr,
				md.phys_addr + size - 1,
				efi_md_typeattr_format(buf, sizeof(buf), &md));

		if (valid)
			ret = fn(mm, &md);
	}
	memunmap(tbl);
	return ret;
}

static int __init ptdump_init(void)
{
	if (!efi_enabled(EFI_RUNTIME_SERVICES))
		return 0;

	return ptdump_debugfs_register(&efi_ptdump_info, "efi_page_tables");
}

void efi_setup_page_tables(void)
{
	efi_scratch.efi_pgt = (pgd_t *)(unsigned long)real_mode_header->trampoline_pgd;

	if (!efi_enabled(EFI_OLD_MEMMAP))
		efi_scratch.use_pgd = true;
}

acpi_physical_address __init acpi_os_get_root_pointer(void)
{
#ifdef CONFIG_KEXEC
	if (acpi_rsdp)
		return acpi_rsdp;
#endif

	if (efi_enabled(EFI_CONFIG_TABLES)) {
		if (efi.acpi20 != EFI_INVALID_TABLE_ADDR)
			return efi.acpi20;
		else if (efi.acpi != EFI_INVALID_TABLE_ADDR)
			return efi.acpi;
		else {
			printk(KERN_ERR PREFIX
			       "System description tables not found\n");
			return 0;
		}
	} else if (IS_ENABLED(CONFIG_ACPI_LEGACY_TABLES_LOOKUP)) {
		acpi_physical_address pa = 0;

		acpi_find_root_pointer(&pa);
		return pa;
	}

	return 0;
}

int efivars_sysfs_init(void)
{
    struct kobject *parent_kobj = efivars_kobject();
    int error = 0;

    if (!efi_enabled(EFI_RUNTIME_SERVICES))
        return -ENODEV;

    /* No efivars has been registered yet */
    if (!parent_kobj)
        return 0;

    printk(KERN_INFO "EFI Variables Facility v%s %s\n", EFIVARS_VERSION,
           EFIVARS_DATE);

    efivars_kset = kset_create_and_add("vars", NULL, parent_kobj);
    if (!efivars_kset) {
        printk(KERN_ERR "efivars: Subsystem registration failed.\n");
        return -ENOMEM;
    }

    efivar_init(efivars_sysfs_callback, NULL, false,
                true, &efivar_sysfs_list);

    error = create_efivars_bin_attributes();
    if (error) {
        efivars_sysfs_exit();
        return error;
    }

    INIT_WORK(&efivar_work, efivar_update_sysfs_entries);

    return 0;
}

/*
 * We need our own copy of the higher levels of the page tables
 * because we want to avoid inserting EFI region mappings (EFI_VA_END
 * to EFI_VA_START) into the standard kernel page tables. Everything
 * else can be shared, see efi_sync_low_kernel_mappings().
 */
int __init efi_alloc_page_tables(void)
{
	pgd_t *pgd;
	p4d_t *p4d;
	pud_t *pud;
	gfp_t gfp_mask;

	if (efi_enabled(EFI_OLD_MEMMAP))
		return 0;

	gfp_mask = GFP_KERNEL | __GFP_NOTRACK | __GFP_ZERO;
	efi_pgd = (pgd_t *)__get_free_page(gfp_mask);
	if (!efi_pgd)
		return -ENOMEM;

	pgd = efi_pgd + pgd_index(EFI_VA_END);
	p4d = p4d_alloc(&init_mm, pgd, EFI_VA_END);
	if (!p4d) {
		free_page((unsigned long)efi_pgd);
		return -ENOMEM;
	}

	pud = pud_alloc(&init_mm, p4d, EFI_VA_END);
	if (!pud) {
		if (CONFIG_PGTABLE_LEVELS > 4)
			free_page((unsigned long) pgd_page_vaddr(*pgd));
		free_page((unsigned long)efi_pgd);
		return -ENOMEM;
	}

	return 0;
}

/*
 * We need our own copy of the higher levels of the page tables
 * because we want to avoid inserting EFI region mappings (EFI_VA_END
 * to EFI_VA_START) into the standard kernel page tables. Everything
 * else can be shared, see efi_sync_low_kernel_mappings().
 */
int __init efi_alloc_page_tables(void)
{
	pgd_t *pgd;
	pud_t *pud;
	gfp_t gfp_mask;

	if (efi_enabled(EFI_OLD_MEMMAP))
		return 0;

	gfp_mask = GFP_KERNEL | __GFP_NOTRACK | __GFP_ZERO;
	efi_pgd = (pgd_t *)__get_free_page(gfp_mask);
	if (!efi_pgd)
		return -ENOMEM;

	pgd = efi_pgd + pgd_index(EFI_VA_END);

	pud = pud_alloc_one(NULL, 0);
	if (!pud) {
		free_page((unsigned long)efi_pgd);
		return -ENOMEM;
	}

	pgd_populate(NULL, pgd, pud);

	return 0;
}

void efi_reboot(enum reboot_mode reboot_mode, const char *__unused)
{
	const char *str[] = { "cold", "warm", "shutdown", "platform" };
	int efi_mode, cap_reset_mode;

	if (!efi_enabled(EFI_RUNTIME_SERVICES))
		return;

	switch (reboot_mode) {
	case REBOOT_WARM:
	case REBOOT_SOFT:
		efi_mode = EFI_RESET_WARM;
		break;
	default:
		efi_mode = EFI_RESET_COLD;
		break;
	}

	/*
	 * If a quirk forced an EFI reset mode, always use that.
	 */
	if (efi_reboot_quirk_mode != -1)
		efi_mode = efi_reboot_quirk_mode;

	if (efi_capsule_pending(&cap_reset_mode)) {
		if (efi_mode != cap_reset_mode)
			printk(KERN_CRIT "efi: %s reset requested but pending "
			       "capsule update requires %s reset... Performing "
			       "%s reset.\n", str[efi_mode], str[cap_reset_mode],
			       str[cap_reset_mode]);
		efi_mode = cap_reset_mode;
	}

	efi.reset_system(efi_mode, EFI_SUCCESS, 0, NULL);
}

pgd_t * __init efi_call_phys_prolog(void)
{
	unsigned long vaddress;
	pgd_t *save_pgd;

	int pgd;
	int n_pgds;

	if (!efi_enabled(EFI_OLD_MEMMAP)) {
		save_pgd = (pgd_t *)read_cr3();
		write_cr3((unsigned long)efi_scratch.efi_pgt);
		goto out;
	}

	early_code_mapping_set_exec(1);

	n_pgds = DIV_ROUND_UP((max_pfn << PAGE_SHIFT), PGDIR_SIZE);
	save_pgd = kmalloc_array(n_pgds, sizeof(*save_pgd), GFP_KERNEL);

	for (pgd = 0; pgd < n_pgds; pgd++) {
		save_pgd[pgd] = *pgd_offset_k(pgd * PGDIR_SIZE);
		vaddress = (unsigned long)__va(pgd * PGDIR_SIZE);
		set_pgd(pgd_offset_k(pgd * PGDIR_SIZE), *pgd_offset_k(vaddress));
	}
out:
	__flush_tlb_all();

	return save_pgd;
}

/*
 * Restart requires that the secondary CPUs stop performing any activity
 * while the primary CPU resets the system. Systems with multiple CPUs must
 * provide a HW restart implementation, to ensure that all CPUs reset at once.
 * This is required so that any code running after reset on the primary CPU
 * doesn't have to co-ordinate with other CPUs to ensure they aren't still
 * executing pre-reset code, and using RAM that the primary CPU's code wishes
 * to use. Implementing such co-ordination would be essentially impossible.
 */
void machine_restart(char *cmd)
{
	/* Disable interrupts first */
	local_irq_disable();
	smp_send_stop();

	/*
	 * UpdateCapsule() depends on the system being reset via
	 * ResetSystem().
	 */
	if (efi_enabled(EFI_RUNTIME_SERVICES))
		efi_reboot(reboot_mode, NULL);

	/* Now call the architecture specific reboot code. */
	if (arm_pm_restart)
		arm_pm_restart(reboot_mode, cmd);
	else
		do_kernel_restart(cmd);

	/*
	 * Whoops - the architecture was unable to reboot.
	 */
	printk("Reboot failed -- System halted\n");
	while (1);
}

void __init efi_runtime_mkexec(void)
{
	if (!efi_enabled(EFI_OLD_MEMMAP))
		return;

	if (__supported_pte_mask & _PAGE_NX)
		runtime_code_page_mkexec();
}

void __init efi_dump_pagetable(void)
{
#ifdef CONFIG_EFI_PGT_DUMP
	if (efi_enabled(EFI_OLD_MEMMAP))
		ptdump_walk_pgd_level(NULL, swapper_pg_dir);
	else
		ptdump_walk_pgd_level(NULL, efi_pgd);
#endif
}

static int __init rtc_init(void)
{
	if (efi_enabled(EFI_RUNTIME_SERVICES))
		if (platform_device_register(&rtc_efi_dev) < 0)
			pr_err("unable to register rtc device...\n");

	/* not necessarily an error */
	return 0;
}

static __init int efivarfs_init(void)
{
	if (!efi_enabled(EFI_RUNTIME_SERVICES))
		return 0;

	if (!efivars_kobject())
		return 0;

	return register_filesystem(&efivarfs_type);
}

/*
 * Enable the UEFI Runtime Services if all prerequisites are in place, i.e.,
 * non-early mapping of the UEFI system table and virtual mappings for all
 * EFI_MEMORY_RUNTIME regions.
 */
static int __init arm_enable_runtime_services(void)
{
	u64 mapsize;

	if (!efi_enabled(EFI_BOOT)) {
		pr_info("EFI services will not be available.\n");
		return 0;
	}

	efi_memmap_unmap();

	mapsize = efi.memmap.desc_size * efi.memmap.nr_map;

	if (efi_memmap_init_late(efi.memmap.phys_map, mapsize)) {
		pr_err("Failed to remap EFI memory map\n");
		return 0;
	}

	if (efi_runtime_disabled()) {
		pr_info("EFI runtime services will be disabled.\n");
		return 0;
	}

	if (efi_enabled(EFI_RUNTIME_SERVICES)) {
		pr_info("EFI runtime services access via paravirt.\n");
		return 0;
	}

	pr_info("Remapping and enabling EFI services.\n");

	if (!efi_virtmap_init()) {
		pr_err("UEFI virtual mapping missing or invalid -- runtime services will not be available\n");
		return -ENOMEM;
	}

	/* Set up runtime services function pointers */
	efi_native_runtime_setup();
	set_bit(EFI_RUNTIME_SERVICES, &efi.flags);

	return 0;
}

static int __init efi_shutdown_init(void)
{
	if (!efi_enabled(EFI_RUNTIME_SERVICES))
		return -ENODEV;

	if (efi_poweroff_required()) {
		orig_pm_power_off = pm_power_off;
		pm_power_off = efi_power_off;
	}

	return 0;
}

static int __init efi_capsule_loader_init(void)
{
	int ret;

	if (!efi_enabled(EFI_RUNTIME_SERVICES))
		return -ENODEV;

	ret = misc_register(&efi_capsule_misc);
	if (ret)
		pr_err("Unable to register capsule loader device\n");

	return ret;
}

void __init efi_map_region(efi_memory_desc_t *md)
{
	unsigned long size = md->num_pages << PAGE_SHIFT;
	u64 pa = md->phys_addr;

	if (efi_enabled(EFI_OLD_MEMMAP))
		return old_map_region(md);

	/*
	 * Make sure the 1:1 mappings are present as a catch-all for b0rked
	 * firmware which doesn't update all internal pointers after switching
	 * to virtual mode and would otherwise crap on us.
	 */
	__map_region(md, md->phys_addr);

	/*
	 * Enforce the 1:1 mapping as the default virtual address when
	 * booting in EFI mixed mode, because even though we may be
	 * running a 64-bit kernel, the firmware may only be 32-bit.
	 */
	if (!efi_is_native () && IS_ENABLED(CONFIG_EFI_MIXED)) {
		md->virt_addr = md->phys_addr;
		return;
	}

	efi_va -= size;

	/* Is PA 2M-aligned? */
	if (!(pa & (PMD_SIZE - 1))) {
		efi_va &= PMD_MASK;
	} else {
		u64 pa_offset = pa & (PMD_SIZE - 1);
		u64 prev_va = efi_va;

		/* get us the same offset within this 2M page */
		efi_va = (efi_va & PMD_MASK) + pa_offset;

		if (efi_va > prev_va)
			efi_va -= PMD_SIZE;
	}

	if (efi_va < EFI_VA_END) {
		pr_warn(FW_WARN "VA address range overflow!\n");
		return;
	}

	/* Do the VA map */
	__map_region(md, efi_va);
	md->virt_addr = efi_va;
}

static void __init ms_hyperv_init_platform(void)
{
	/*
	 * Extract the features and hints
	 */
	ms_hyperv.features = cpuid_eax(HYPERV_CPUID_FEATURES);
	ms_hyperv.misc_features = cpuid_edx(HYPERV_CPUID_FEATURES);
	ms_hyperv.hints    = cpuid_eax(HYPERV_CPUID_ENLIGHTMENT_INFO);

	pr_info("HyperV: features 0x%x, hints 0x%x\n",
		ms_hyperv.features, ms_hyperv.hints);

#ifdef CONFIG_X86_LOCAL_APIC
	if (ms_hyperv.features & HV_X64_MSR_APIC_FREQUENCY_AVAILABLE) {
		/*
		 * Get the APIC frequency.
		 */
		u64	hv_lapic_frequency;

		rdmsrl(HV_X64_MSR_APIC_FREQUENCY, hv_lapic_frequency);
		hv_lapic_frequency = div_u64(hv_lapic_frequency, HZ);
		lapic_timer_frequency = hv_lapic_frequency;
		pr_info("HyperV: LAPIC Timer Frequency: %#x\n",
			lapic_timer_frequency);
	}

	register_nmi_handler(NMI_UNKNOWN, hv_nmi_unknown, NMI_FLAG_FIRST,
			     "hv_nmi_unknown");
#endif

	if (ms_hyperv.features & HV_X64_MSR_TIME_REF_COUNT_AVAILABLE)
		clocksource_register_hz(&hyperv_cs, NSEC_PER_SEC/100);

#ifdef CONFIG_X86_IO_APIC
	no_timer_check = 1;
#endif

#if IS_ENABLED(CONFIG_HYPERV) && defined(CONFIG_KEXEC_CORE)
	machine_ops.shutdown = hv_machine_shutdown;
	machine_ops.crash_shutdown = hv_machine_crash_shutdown;
#endif
	mark_tsc_unstable("running on Hyper-V");

	/*
	 * Generation 2 instances don't support reading the NMI status from
	 * 0x61 port.
	 */
	if (efi_enabled(EFI_BOOT))
		x86_platform.get_nmi_reason = hv_get_nmi_reason;
}