[deliverable/linux.git] / arch / x86 / platform / efi / efi.c

/*
 * Common EFI (Extensible Firmware Interface) support functions
 * Based on Extensible Firmware Interface Specification version 1.0
 *
 * Copyright (C) 1999 VA Linux Systems
 * Copyright (C) 1999 Walt Drummond <drummond@valinux.com>
 * Copyright (C) 1999-2002 Hewlett-Packard Co.
 *      David Mosberger-Tang <davidm@hpl.hp.com>
 *      Stephane Eranian <eranian@hpl.hp.com>
 * Copyright (C) 2005-2008 Intel Co.
 *      Fenghua Yu <fenghua.yu@intel.com>
 *      Bibo Mao <bibo.mao@intel.com>
 *      Chandramouli Narayanan <mouli@linux.intel.com>
 *      Huang Ying <ying.huang@intel.com>
 * Copyright (C) 2013 SuSE Labs
 *      Borislav Petkov <bp@suse.de> - runtime services VA mapping
 *
 * Copied from efi_32.c to eliminate the duplicated code between EFI
 * 32/64 support code. --ying 2007-10-26
 *
 * All EFI Runtime Services are not implemented yet as EFI only
 * supports physical mode addressing on SoftSDV. This is to be fixed
 * in a future version.  --drummond 1999-07-20
 *
 * Implemented EFI runtime services and virtual mode calls.  --davidm
 *
 * Goutham Rao: <goutham.rao@intel.com>
 *      Skip non-WB memory and ignore empty memory ranges.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/efi.h>
#include <linux/efi-bgrt.h>
#include <linux/export.h>
#include <linux/bootmem.h>
#include <linux/slab.h>
#include <linux/memblock.h>
#include <linux/spinlock.h>
#include <linux/uaccess.h>
#include <linux/time.h>
#include <linux/io.h>
#include <linux/reboot.h>
#include <linux/bcd.h>

#include <asm/setup.h>
#include <asm/efi.h>
#include <asm/time.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
#include <asm/x86_init.h>
#include <asm/rtc.h>
#include <asm/uv/uv.h>

#define EFI_DEBUG

struct efi_memory_map memmap;

static struct efi efi_phys __initdata;
static efi_system_table_t efi_systab __initdata;

static efi_config_table_type_t arch_tables[] __initdata = {
#ifdef CONFIG_X86_UV
        {UV_SYSTEM_TABLE_GUID, "UVsystab", &efi.uv_systab},
#endif
        {NULL_GUID, NULL, NULL},
};

u64 efi_setup;          /* efi setup_data physical address */

static int add_efi_memmap __initdata;
static int __init setup_add_efi_memmap(char *arg)
{
        add_efi_memmap = 1;
        return 0;
}
early_param("add_efi_memmap", setup_add_efi_memmap);

static efi_status_t __init phys_efi_set_virtual_address_map(
        unsigned long memory_map_size,
        unsigned long descriptor_size,
        u32 descriptor_version,
        efi_memory_desc_t *virtual_map)
{
        efi_status_t status;

        efi_call_phys_prolog();
        status = efi_call_phys(efi_phys.set_virtual_address_map,
                               memory_map_size, descriptor_size,
                               descriptor_version, virtual_map);
        efi_call_phys_epilog();
        return status;
}

void efi_get_time(struct timespec *now)
{
        efi_status_t status;
        efi_time_t eft;
        efi_time_cap_t cap;

        status = efi.get_time(&eft, &cap);
        if (status != EFI_SUCCESS)
                pr_err("Oops: efitime: can't read time!\n");

        now->tv_sec = mktime(eft.year, eft.month, eft.day, eft.hour,
                             eft.minute, eft.second);
        now->tv_nsec = 0;
}

/*
 * Tell the kernel about the EFI memory map.  This might include
 * more than the max 128 entries that can fit in the e820 legacy
 * (zeropage) memory map.
 */

static void __init do_add_efi_memmap(void)
{
        void *p;

        for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {
                efi_memory_desc_t *md = p;
                unsigned long long start = md->phys_addr;
                unsigned long long size = md->num_pages << EFI_PAGE_SHIFT;
                int e820_type;

                switch (md->type) {
                case EFI_LOADER_CODE:
                case EFI_LOADER_DATA:
                case EFI_BOOT_SERVICES_CODE:
                case EFI_BOOT_SERVICES_DATA:
                case EFI_CONVENTIONAL_MEMORY:
                        if (md->attribute & EFI_MEMORY_WB)
                                e820_type = E820_RAM;
                        else
                                e820_type = E820_RESERVED;
                        break;
                case EFI_ACPI_RECLAIM_MEMORY:
                        e820_type = E820_ACPI;
                        break;
                case EFI_ACPI_MEMORY_NVS:
                        e820_type = E820_NVS;
                        break;
                case EFI_UNUSABLE_MEMORY:
                        e820_type = E820_UNUSABLE;
                        break;
                default:
                        /*
                         * EFI_RESERVED_TYPE EFI_RUNTIME_SERVICES_CODE
                         * EFI_RUNTIME_SERVICES_DATA EFI_MEMORY_MAPPED_IO
                         * EFI_MEMORY_MAPPED_IO_PORT_SPACE EFI_PAL_CODE
                         */
                        e820_type = E820_RESERVED;
                        break;
                }
                e820_add_region(start, size, e820_type);
        }
        sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map);
}

int __init efi_memblock_x86_reserve_range(void)
{
        struct efi_info *e = &boot_params.efi_info;
        unsigned long pmap;

        if (efi_enabled(EFI_PARAVIRT))
                return 0;

#ifdef CONFIG_X86_32
        /* Can't handle data above 4GB at this time */
        if (e->efi_memmap_hi) {
                pr_err("Memory map is above 4GB, disabling EFI.\n");
                return -EINVAL;
        }
        pmap =  e->efi_memmap;
#else
        pmap = (e->efi_memmap | ((__u64)e->efi_memmap_hi << 32));
#endif
        memmap.phys_map         = (void *)pmap;
        memmap.nr_map           = e->efi_memmap_size /
                                  e->efi_memdesc_size;
        memmap.desc_size        = e->efi_memdesc_size;
        memmap.desc_version     = e->efi_memdesc_version;

        memblock_reserve(pmap, memmap.nr_map * memmap.desc_size);

        efi.memmap = &memmap;

        return 0;
}

static void __init print_efi_memmap(void)
{
#ifdef EFI_DEBUG
        efi_memory_desc_t *md;
        void *p;
        int i;

        for (p = memmap.map, i = 0;
             p < memmap.map_end;
             p += memmap.desc_size, i++) {
                char buf[64];

                md = p;
                pr_info("mem%02u: %s range=[0x%016llx-0x%016llx) (%lluMB)\n",
                        i, efi_md_typeattr_format(buf, sizeof(buf), md),
                        md->phys_addr,
                        md->phys_addr + (md->num_pages << EFI_PAGE_SHIFT),
                        (md->num_pages >> (20 - EFI_PAGE_SHIFT)));
        }
#endif  /*  EFI_DEBUG  */
}

void __init efi_unmap_memmap(void)
{
        clear_bit(EFI_MEMMAP, &efi.flags);
        if (memmap.map) {
                early_memunmap(memmap.map, memmap.nr_map * memmap.desc_size);
                memmap.map = NULL;
        }
}

static int __init efi_systab_init(void *phys)
{
        if (efi_enabled(EFI_64BIT)) {
                efi_system_table_64_t *systab64;
                struct efi_setup_data *data = NULL;
                u64 tmp = 0;

                if (efi_setup) {
                        data = early_memremap(efi_setup, sizeof(*data));
                        if (!data)
                                return -ENOMEM;
                }
                systab64 = early_memremap((unsigned long)phys,
                                         sizeof(*systab64));
                if (systab64 == NULL) {
                        pr_err("Couldn't map the system table!\n");
                        if (data)
                                early_memunmap(data, sizeof(*data));
                        return -ENOMEM;
                }

                efi_systab.hdr = systab64->hdr;
                efi_systab.fw_vendor = data ? (unsigned long)data->fw_vendor :
                                              systab64->fw_vendor;
                tmp |= data ? data->fw_vendor : systab64->fw_vendor;
                efi_systab.fw_revision = systab64->fw_revision;
                efi_systab.con_in_handle = systab64->con_in_handle;
                tmp |= systab64->con_in_handle;
                efi_systab.con_in = systab64->con_in;
                tmp |= systab64->con_in;
                efi_systab.con_out_handle = systab64->con_out_handle;
                tmp |= systab64->con_out_handle;
                efi_systab.con_out = systab64->con_out;
                tmp |= systab64->con_out;
                efi_systab.stderr_handle = systab64->stderr_handle;
                tmp |= systab64->stderr_handle;
                efi_systab.stderr = systab64->stderr;
                tmp |= systab64->stderr;
                efi_systab.runtime = data ?
                                     (void *)(unsigned long)data->runtime :
                                     (void *)(unsigned long)systab64->runtime;
                tmp |= data ? data->runtime : systab64->runtime;
                efi_systab.boottime = (void *)(unsigned long)systab64->boottime;
                tmp |= systab64->boottime;
                efi_systab.nr_tables = systab64->nr_tables;
                efi_systab.tables = data ? (unsigned long)data->tables :
                                           systab64->tables;
                tmp |= data ? data->tables : systab64->tables;

                early_memunmap(systab64, sizeof(*systab64));
                if (data)
                        early_memunmap(data, sizeof(*data));
#ifdef CONFIG_X86_32
                if (tmp >> 32) {
                        pr_err("EFI data located above 4GB, disabling EFI.\n");
                        return -EINVAL;
                }
#endif
        } else {
                efi_system_table_32_t *systab32;

                systab32 = early_memremap((unsigned long)phys,
                                         sizeof(*systab32));
                if (systab32 == NULL) {
                        pr_err("Couldn't map the system table!\n");
                        return -ENOMEM;
                }

                efi_systab.hdr = systab32->hdr;
                efi_systab.fw_vendor = systab32->fw_vendor;
                efi_systab.fw_revision = systab32->fw_revision;
                efi_systab.con_in_handle = systab32->con_in_handle;
                efi_systab.con_in = systab32->con_in;
                efi_systab.con_out_handle = systab32->con_out_handle;
                efi_systab.con_out = systab32->con_out;
                efi_systab.stderr_handle = systab32->stderr_handle;
                efi_systab.stderr = systab32->stderr;
                efi_systab.runtime = (void *)(unsigned long)systab32->runtime;
                efi_systab.boottime = (void *)(unsigned long)systab32->boottime;
                efi_systab.nr_tables = systab32->nr_tables;
                efi_systab.tables = systab32->tables;

                early_memunmap(systab32, sizeof(*systab32));
        }

        efi.systab = &efi_systab;

        /*
         * Verify the EFI Table
         */
        if (efi.systab->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE) {
                pr_err("System table signature incorrect!\n");
                return -EINVAL;
        }
        if ((efi.systab->hdr.revision >> 16) == 0)
                pr_err("Warning: System table version %d.%02d, expected 1.00 or greater!\n",
                       efi.systab->hdr.revision >> 16,
                       efi.systab->hdr.revision & 0xffff);

        set_bit(EFI_SYSTEM_TABLES, &efi.flags);

        return 0;
}

static int __init efi_runtime_init32(void)
{
        efi_runtime_services_32_t *runtime;

        runtime = early_memremap((unsigned long)efi.systab->runtime,
                        sizeof(efi_runtime_services_32_t));
        if (!runtime) {
                pr_err("Could not map the runtime service table!\n");
                return -ENOMEM;
        }

        /*
         * We will only need *early* access to the SetVirtualAddressMap
         * EFI runtime service. All other runtime services will be called
         * via the virtual mapping.
         */
        efi_phys.set_virtual_address_map =
                        (efi_set_virtual_address_map_t *)
                        (unsigned long)runtime->set_virtual_address_map;
        early_memunmap(runtime, sizeof(efi_runtime_services_32_t));

        return 0;
}

static int __init efi_runtime_init64(void)
{
        efi_runtime_services_64_t *runtime;

        runtime = early_memremap((unsigned long)efi.systab->runtime,
                        sizeof(efi_runtime_services_64_t));
        if (!runtime) {
                pr_err("Could not map the runtime service table!\n");
                return -ENOMEM;
        }

        /*
         * We will only need *early* access to the SetVirtualAddressMap
         * EFI runtime service. All other runtime services will be called
         * via the virtual mapping.
         */
        efi_phys.set_virtual_address_map =
                        (efi_set_virtual_address_map_t *)
                        (unsigned long)runtime->set_virtual_address_map;
        early_memunmap(runtime, sizeof(efi_runtime_services_64_t));

        return 0;
}

static int __init efi_runtime_init(void)
{
        int rv;

        /*
         * Check out the runtime services table. We need to map
         * the runtime services table so that we can grab the physical
         * address of several of the EFI runtime functions, needed to
         * set the firmware into virtual mode.
         *
         * When EFI_PARAVIRT is in force then we could not map runtime
         * service memory region because we do not have direct access to it.
         * However, runtime services are available through proxy functions
         * (e.g. in case of Xen dom0 EFI implementation they call special
         * hypercall which executes relevant EFI functions) and that is why
         * they are always enabled.
         */

        if (!efi_enabled(EFI_PARAVIRT)) {
                if (efi_enabled(EFI_64BIT))
                        rv = efi_runtime_init64();
                else
                        rv = efi_runtime_init32();

                if (rv)
                        return rv;
        }

        set_bit(EFI_RUNTIME_SERVICES, &efi.flags);

        return 0;
}

static int __init efi_memmap_init(void)
{
        if (efi_enabled(EFI_PARAVIRT))
                return 0;

        /* Map the EFI memory map */
        memmap.map = early_memremap((unsigned long)memmap.phys_map,
                                   memmap.nr_map * memmap.desc_size);
        if (memmap.map == NULL) {
                pr_err("Could not map the memory map!\n");
                return -ENOMEM;
        }
        memmap.map_end = memmap.map + (memmap.nr_map * memmap.desc_size);

        if (add_efi_memmap)
                do_add_efi_memmap();

        set_bit(EFI_MEMMAP, &efi.flags);

        return 0;
}

void __init efi_init(void)
{
        efi_char16_t *c16;
        char vendor[100] = "unknown";
        int i = 0;
        void *tmp;

#ifdef CONFIG_X86_32
        if (boot_params.efi_info.efi_systab_hi ||
            boot_params.efi_info.efi_memmap_hi) {
                pr_info("Table located above 4GB, disabling EFI.\n");
                return;
        }
        efi_phys.systab = (efi_system_table_t *)boot_params.efi_info.efi_systab;
#else
        efi_phys.systab = (efi_system_table_t *)
                          (boot_params.efi_info.efi_systab |
                          ((__u64)boot_params.efi_info.efi_systab_hi<<32));
#endif

        if (efi_systab_init(efi_phys.systab))
                return;

        efi.config_table = (unsigned long)efi.systab->tables;
        efi.fw_vendor    = (unsigned long)efi.systab->fw_vendor;
        efi.runtime      = (unsigned long)efi.systab->runtime;

        /*
         * Show what we know for posterity
         */
        c16 = tmp = early_memremap(efi.systab->fw_vendor, 2);
        if (c16) {
                for (i = 0; i < sizeof(vendor) - 1 && *c16; ++i)
                        vendor[i] = *c16++;
                vendor[i] = '\0';
        } else
                pr_err("Could not map the firmware vendor!\n");
        early_memunmap(tmp, 2);

        pr_info("EFI v%u.%.02u by %s\n",
                efi.systab->hdr.revision >> 16,
                efi.systab->hdr.revision & 0xffff, vendor);

        if (efi_reuse_config(efi.systab->tables, efi.systab->nr_tables))
                return;

        if (efi_config_init(arch_tables))
                return;

        /*
         * Note: We currently don't support runtime services on an EFI
         * that doesn't match the kernel 32/64-bit mode.
         */

        if (!efi_runtime_supported())
                pr_info("No EFI runtime due to 32/64-bit mismatch with kernel\n");
        else {
                if (efi_runtime_disabled() || efi_runtime_init())
                        return;
        }
        if (efi_memmap_init())
                return;

        if (efi_enabled(EFI_DBG))
                print_efi_memmap();
}

void __init efi_late_init(void)
{
        efi_bgrt_init();
}

void __init efi_set_executable(efi_memory_desc_t *md, bool executable)
{
        u64 addr, npages;

        addr = md->virt_addr;
        npages = md->num_pages;

        memrange_efi_to_native(&addr, &npages);

        if (executable)
                set_memory_x(addr, npages);
        else
                set_memory_nx(addr, npages);
}

void __init runtime_code_page_mkexec(void)
{
        efi_memory_desc_t *md;
        void *p;

        /* Make EFI runtime service code area executable */
        for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {
                md = p;

                if (md->type != EFI_RUNTIME_SERVICES_CODE)
                        continue;

                efi_set_executable(md, true);
        }
}

void __init efi_memory_uc(u64 addr, unsigned long size)
{
        unsigned long page_shift = 1UL << EFI_PAGE_SHIFT;
        u64 npages;

        npages = round_up(size, page_shift) / page_shift;
        memrange_efi_to_native(&addr, &npages);
        set_memory_uc(addr, npages);
}

void __init old_map_region(efi_memory_desc_t *md)
{
        u64 start_pfn, end_pfn, end;
        unsigned long size;
        void *va;

        start_pfn = PFN_DOWN(md->phys_addr);
        size      = md->num_pages << PAGE_SHIFT;
        end       = md->phys_addr + size;
        end_pfn   = PFN_UP(end);

        if (pfn_range_is_mapped(start_pfn, end_pfn)) {
                va = __va(md->phys_addr);

                if (!(md->attribute & EFI_MEMORY_WB))
                        efi_memory_uc((u64)(unsigned long)va, size);
        } else
                va = efi_ioremap(md->phys_addr, size,
                                 md->type, md->attribute);

        md->virt_addr = (u64) (unsigned long) va;
        if (!va)
                pr_err("ioremap of 0x%llX failed!\n",
                       (unsigned long long)md->phys_addr);
}

/* Merge contiguous regions of the same type and attribute */
static void __init efi_merge_regions(void)
{
        void *p;
        efi_memory_desc_t *md, *prev_md = NULL;

        for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {
                u64 prev_size;
                md = p;

                if (!prev_md) {
                        prev_md = md;
                        continue;
                }

                if (prev_md->type != md->type ||
                    prev_md->attribute != md->attribute) {
                        prev_md = md;
                        continue;
                }

                prev_size = prev_md->num_pages << EFI_PAGE_SHIFT;

                if (md->phys_addr == (prev_md->phys_addr + prev_size)) {
                        prev_md->num_pages += md->num_pages;
                        md->type = EFI_RESERVED_TYPE;
                        md->attribute = 0;
                        continue;
                }
                prev_md = md;
        }
}

static void __init get_systab_virt_addr(efi_memory_desc_t *md)
{
        unsigned long size;
        u64 end, systab;

        size = md->num_pages << EFI_PAGE_SHIFT;
        end = md->phys_addr + size;
        systab = (u64)(unsigned long)efi_phys.systab;
        if (md->phys_addr <= systab && systab < end) {
                systab += md->virt_addr - md->phys_addr;
                efi.systab = (efi_system_table_t *)(unsigned long)systab;
        }
}

static void __init save_runtime_map(void)
{
#ifdef CONFIG_KEXEC
        efi_memory_desc_t *md;
        void *tmp, *p, *q = NULL;
        int count = 0;

        if (efi_enabled(EFI_OLD_MEMMAP))
                return;

        for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {
                md = p;

                if (!(md->attribute & EFI_MEMORY_RUNTIME) ||
                    (md->type == EFI_BOOT_SERVICES_CODE) ||
                    (md->type == EFI_BOOT_SERVICES_DATA))
                        continue;
                tmp = krealloc(q, (count + 1) * memmap.desc_size, GFP_KERNEL);
                if (!tmp)
                        goto out;
                q = tmp;

                memcpy(q + count * memmap.desc_size, md, memmap.desc_size);
                count++;
        }

        efi_runtime_map_setup(q, count, memmap.desc_size);
        return;

out:
        kfree(q);
        pr_err("Error saving runtime map, efi runtime on kexec non-functional!!\n");
#endif
}

static void *realloc_pages(void *old_memmap, int old_shift)
{
        void *ret;

        ret = (void *)__get_free_pages(GFP_KERNEL, old_shift + 1);
        if (!ret)
                goto out;

        /*
         * A first-time allocation doesn't have anything to copy.
         */
        if (!old_memmap)
                return ret;

        memcpy(ret, old_memmap, PAGE_SIZE << old_shift);

out:
        free_pages((unsigned long)old_memmap, old_shift);
        return ret;
}

/*
 * Map the efi memory ranges of the runtime services and update new_mmap with
 * virtual addresses.
 */
static void * __init efi_map_regions(int *count, int *pg_shift)
{
        void *p, *new_memmap = NULL;
        unsigned long left = 0;
        efi_memory_desc_t *md;

        for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {
                md = p;
                if (!(md->attribute & EFI_MEMORY_RUNTIME)) {
#ifdef CONFIG_X86_64
                        if (md->type != EFI_BOOT_SERVICES_CODE &&
                            md->type != EFI_BOOT_SERVICES_DATA)
#endif
                                continue;
                }

                efi_map_region(md);
                get_systab_virt_addr(md);

                if (left < memmap.desc_size) {
                        new_memmap = realloc_pages(new_memmap, *pg_shift);
                        if (!new_memmap)
                                return NULL;

                        left += PAGE_SIZE << *pg_shift;
                        (*pg_shift)++;
                }

                memcpy(new_memmap + (*count * memmap.desc_size), md,
                       memmap.desc_size);

                left -= memmap.desc_size;
                (*count)++;
        }

        return new_memmap;
}

static void __init kexec_enter_virtual_mode(void)
{
#ifdef CONFIG_KEXEC
        efi_memory_desc_t *md;
        void *p;

        efi.systab = NULL;

        /*
         * We don't do virtual mode, since we don't do runtime services, on
         * non-native EFI
         */
        if (!efi_is_native()) {
                efi_unmap_memmap();
                clear_bit(EFI_RUNTIME_SERVICES, &efi.flags);
                return;
        }

        /*
        * Map efi regions which were passed via setup_data. The virt_addr is a
        * fixed addr which was used in first kernel of a kexec boot.
        */
        for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {
                md = p;
                efi_map_region_fixed(md); /* FIXME: add error handling */
                get_systab_virt_addr(md);
        }

        save_runtime_map();

        BUG_ON(!efi.systab);

        efi_sync_low_kernel_mappings();

        /*
         * Now that EFI is in virtual mode, update the function
         * pointers in the runtime service table to the new virtual addresses.
         *
         * Call EFI services through wrapper functions.
         */
        efi.runtime_version = efi_systab.hdr.revision;

        efi_native_runtime_setup();

        efi.set_virtual_address_map = NULL;

        if (efi_enabled(EFI_OLD_MEMMAP) && (__supported_pte_mask & _PAGE_NX))
                runtime_code_page_mkexec();

        /* clean DUMMY object */
        efi_delete_dummy_variable();
#endif
}

/*
 * This function will switch the EFI runtime services to virtual mode.
 * Essentially, we look through the EFI memmap and map every region that
 * has the runtime attribute bit set in its memory descriptor into the
 * ->trampoline_pgd page table using a top-down VA allocation scheme.
 *
 * The old method which used to update that memory descriptor with the
 * virtual address obtained from ioremap() is still supported when the
 * kernel is booted with efi=old_map on its command line. Same old
 * method enabled the runtime services to be called without having to
 * thunk back into physical mode for every invocation.
 *
 * The new method does a pagetable switch in a preemption-safe manner
 * so that we're in a different address space when calling a runtime
 * function. For function arguments passing we do copy the PGDs of the
 * kernel page table into ->trampoline_pgd prior to each call.
 *
 * Specially for kexec boot, efi runtime maps in previous kernel should
 * be passed in via setup_data. In that case runtime ranges will be mapped
 * to the same virtual addresses as the first kernel, see
 * kexec_enter_virtual_mode().
 */
static void __init __efi_enter_virtual_mode(void)
{
        int count = 0, pg_shift = 0;
        void *new_memmap = NULL;
        efi_status_t status;

        efi.systab = NULL;

        efi_merge_regions();
        new_memmap = efi_map_regions(&count, &pg_shift);
        if (!new_memmap) {
                pr_err("Error reallocating memory, EFI runtime non-functional!\n");
                clear_bit(EFI_RUNTIME_SERVICES, &efi.flags);
                return;
        }

        save_runtime_map();

        BUG_ON(!efi.systab);

        if (efi_setup_page_tables(__pa(new_memmap), 1 << pg_shift)) {
                clear_bit(EFI_RUNTIME_SERVICES, &efi.flags);
                return;
        }

        efi_sync_low_kernel_mappings();
        efi_dump_pagetable();

        if (efi_is_native()) {
                status = phys_efi_set_virtual_address_map(
                                memmap.desc_size * count,
                                memmap.desc_size,
                                memmap.desc_version,
                                (efi_memory_desc_t *)__pa(new_memmap));
        } else {
                status = efi_thunk_set_virtual_address_map(
                                efi_phys.set_virtual_address_map,
                                memmap.desc_size * count,
                                memmap.desc_size,
                                memmap.desc_version,
                                (efi_memory_desc_t *)__pa(new_memmap));
        }

        if (status != EFI_SUCCESS) {
                pr_alert("Unable to switch EFI into virtual mode (status=%lx)!\n",
                         status);
                panic("EFI call to SetVirtualAddressMap() failed!");
        }

        /*
         * Now that EFI is in virtual mode, update the function
         * pointers in the runtime service table to the new virtual addresses.
         *
         * Call EFI services through wrapper functions.
         */
        efi.runtime_version = efi_systab.hdr.revision;

        if (efi_is_native())
                efi_native_runtime_setup();
        else
                efi_thunk_runtime_setup();

        efi.set_virtual_address_map = NULL;

        efi_runtime_mkexec();

        /*
         * We mapped the descriptor array into the EFI pagetable above but we're
         * not unmapping it here. Here's why:
         *
         * We're copying select PGDs from the kernel page table to the EFI page
         * table and when we do so and make changes to those PGDs like unmapping
         * stuff from them, those changes appear in the kernel page table and we
         * go boom.
         *
         * From setup_real_mode():
         *
         * ...
         * trampoline_pgd[0] = init_level4_pgt[pgd_index(__PAGE_OFFSET)].pgd;
         *
         * In this particular case, our allocation is in PGD 0 of the EFI page
         * table but we've copied that PGD from PGD[272] of the EFI page table:
         *
         *      pgd_index(__PAGE_OFFSET = 0xffff880000000000) = 272
         *
         * where the direct memory mapping in kernel space is.
         *
         * new_memmap's VA comes from that direct mapping and thus clearing it,
         * it would get cleared in the kernel page table too.
         *
         * efi_cleanup_page_tables(__pa(new_memmap), 1 << pg_shift);
         */
        free_pages((unsigned long)new_memmap, pg_shift);

        /* clean DUMMY object */
        efi_delete_dummy_variable();
}

void __init efi_enter_virtual_mode(void)
{
        if (efi_enabled(EFI_PARAVIRT))
                return;

        if (efi_setup)
                kexec_enter_virtual_mode();
        else
                __efi_enter_virtual_mode();
}

/*
 * Convenience functions to obtain memory types and attributes
 */
u32 efi_mem_type(unsigned long phys_addr)
{
        efi_memory_desc_t *md;
        void *p;

        if (!efi_enabled(EFI_MEMMAP))
                return 0;

        for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {
                md = p;
                if ((md->phys_addr <= phys_addr) &&
                    (phys_addr < (md->phys_addr +
                                  (md->num_pages << EFI_PAGE_SHIFT))))
                        return md->type;
        }
        return 0;
}

u64 efi_mem_attributes(unsigned long phys_addr)
{
        efi_memory_desc_t *md;
        void *p;

        if (!efi_enabled(EFI_MEMMAP))
                return 0;

        for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {
                md = p;
                if ((md->phys_addr <= phys_addr) &&
                    (phys_addr < (md->phys_addr +
                                  (md->num_pages << EFI_PAGE_SHIFT))))
                        return md->attribute;
        }
        return 0;
}

static int __init arch_parse_efi_cmdline(char *str)
{
        if (parse_option_str(str, "old_map"))
                set_bit(EFI_OLD_MEMMAP, &efi.flags);
        if (parse_option_str(str, "debug"))
                set_bit(EFI_DBG, &efi.flags);

        return 0;
}
early_param("efi", arch_parse_efi_cmdline);