// Copyright 2016 The Fuchsia Authors
// Copyright (c) 2009 Corey Tabaka
// Copyright (c) 2015 Intel Corporation
// Copyright (c) 2016 Travis Geiselbrecht
//
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file or at
// https://opensource.org/licenses/MIT

#include "platform_p.h"

#include <arch/mmu.h>
#include <arch/mp.h>
#include <arch/ops.h>
#include <arch/x86.h>
#include <arch/x86/apic.h>
#include <arch/x86/cpu_topology.h>
#include <arch/x86/mmu.h>
#include <assert.h>
#if defined(WITH_KERNEL_PCIE)
#include <dev/pcie_bus_driver.h>
#endif
#include <dev/uart.h>
#include <err.h>
#include <fbl/alloc_checker.h>
#include <kernel/cmdline.h>
#include <lib/debuglog.h>
#include <libzbi/zbi-cpp.h>
#include <lk/init.h>
#include <mexec.h>
#include <platform.h>
#include <platform/console.h>
#include <platform/keyboard.h>
#include <platform/pc.h>
#include <platform/pc/acpi.h>
#include <platform/pc/bootloader.h>
#include <platform/pc/smbios.h>
#include <string.h>
#include <trace.h>
#include <vm/bootalloc.h>
#include <vm/bootreserve.h>
#include <vm/physmap.h>
#include <vm/pmm.h>
#include <vm/vm_aspace.h>
#include <zircon/boot/e820.h>
#include <zircon/boot/image.h>
#include <zircon/pixelformat.h>
#include <zircon/types.h>

#include <lib/cksum.h>

extern "C" {
#include <efi/runtime-services.h>
#include <efi/system-table.h>
};

#define LOCAL_TRACE 0

extern zbi_header_t* _zbi_base;

pc_bootloader_info_t bootloader;

// Stashed values from ZBI_TYPE_CRASHLOG if we saw it
static const void* last_crashlog = nullptr;
static size_t last_crashlog_len = 0;

// convert from legacy format
static unsigned pixel_format_fixup(unsigned pf) {
    switch (pf) {
    case 1:
        return ZX_PIXEL_FORMAT_RGB_565;
    case 2:
        return ZX_PIXEL_FORMAT_RGB_332;
    case 3:
        return ZX_PIXEL_FORMAT_RGB_2220;
    case 4:
        return ZX_PIXEL_FORMAT_ARGB_8888;
    case 5:
        return ZX_PIXEL_FORMAT_RGB_x888;
    default:
        return pf;
    }
}

static bool early_console_disabled;

zbi_result_t process_zbi_item(zbi_header_t* hdr, void* payload, void* cookie) {
    switch (hdr->type) {
    case ZBI_TYPE_ACPI_RSDP:
        if (hdr->length >= sizeof(uint64_t)) {
            bootloader.acpi_rsdp = *((uint64_t*)payload);
        }
        break;
    case ZBI_TYPE_SMBIOS:
        if (hdr->length >= sizeof(uint64_t)) {
            bootloader.smbios = *((uint64_t*)payload);
        }
        break;
    case ZBI_TYPE_EFI_SYSTEM_TABLE:
        if (hdr->length >= sizeof(uint64_t)) {
            bootloader.efi_system_table = (void*)*((uint64_t*)payload);
        }
        break;
    case ZBI_TYPE_FRAMEBUFFER: {
        if (hdr->length >= sizeof(zbi_swfb_t)) {
            memcpy(&bootloader.fb, payload, sizeof(zbi_swfb_t));
        }
        bootloader.fb.format = pixel_format_fixup(bootloader.fb.format);
        break;
    }
    case ZBI_TYPE_CMDLINE:
        if (hdr->length > 0) {
            ((char*)payload)[hdr->length - 1] = 0;
            cmdline_append((char*)payload);
        }
        break;
    case ZBI_TYPE_EFI_MEMORY_MAP:
        bootloader.efi_mmap = payload;
        bootloader.efi_mmap_size = hdr->length;
        break;
    case ZBI_TYPE_E820_TABLE:
        bootloader.e820_table = payload;
        bootloader.e820_count = hdr->length / sizeof(e820entry_t);
        break;
    case ZBI_TYPE_NVRAM_DEPRECATED:
    // fallthrough: this is a legacy/typo variant
    case ZBI_TYPE_NVRAM:
        if (hdr->length >= sizeof(zbi_nvram_t)) {
            memcpy(&bootloader.nvram, payload, sizeof(zbi_nvram_t));
        }
        break;
    case ZBI_TYPE_DEBUG_UART:
        if (hdr->length >= sizeof(zbi_uart_t)) {
            memcpy(&bootloader.uart, payload, sizeof(zbi_uart_t));
        }
        break;
    case ZBI_TYPE_CRASHLOG:
        last_crashlog = payload;
        last_crashlog_len = hdr->length;
        break;
    case ZBI_TYPE_DISCARD:
        break;
    }
    return ZBI_RESULT_OK;
}

static void process_zbi(zbi_header_t* hdr, uintptr_t phys) {
    uint8_t* zbi_base = reinterpret_cast<uint8_t*>(hdr);

    zbi::Zbi image(zbi_base);

    // Make sure the image is in good shape.
    zbi_header_t* bad_hdr;
    zbi_result_t result = image.Check(&bad_hdr);
    if (result != ZBI_RESULT_OK) {
        printf("zbi: invalid %08x %08x %08x %08x, retcode = %d\n",
               bad_hdr->type, bad_hdr->length, bad_hdr->extra, bad_hdr->flags,
               result);
        return;
    }

    printf("zbi: @ %p (%u bytes)\n", image.Base(), image.Length());

    result = image.ForEach(process_zbi_item, nullptr);
    if (result != ZBI_RESULT_OK) {
        printf("zbi: failed to process bootdata, reason = %d\n", result);
        return;
    }

    boot_alloc_reserve(phys, image.Length());
    bootloader.ramdisk_base = phys;
    bootloader.ramdisk_size = image.Length();
}

extern bool halt_on_panic;

static void platform_save_bootloader_data(void) {
    if (_zbi_base != NULL) {
        zbi_header_t* bd = (zbi_header_t*)X86_PHYS_TO_VIRT(_zbi_base);
        process_zbi(bd, (uintptr_t)_zbi_base);
    }

    halt_on_panic = cmdline_get_bool("kernel.halt-on-panic", false);
}

static void* ramdisk_base;
static size_t ramdisk_size;

static void platform_preserve_ramdisk(void) {
    if (bootloader.ramdisk_size == 0) {
        return;
    }
    if (bootloader.ramdisk_base == 0) {
        return;
    }

    size_t pages = ROUNDUP_PAGE_SIZE(bootloader.ramdisk_size) / PAGE_SIZE;
    ramdisk_base = paddr_to_physmap(bootloader.ramdisk_base);
    ramdisk_size = pages * PAGE_SIZE;

    // add the ramdisk to the boot reserve list
    boot_reserve_add_range(bootloader.ramdisk_base, ramdisk_size);
}

void* platform_get_ramdisk(size_t* size) {
    if (ramdisk_base) {
        *size = ramdisk_size;
        return ramdisk_base;
    } else {
        *size = 0;
        return NULL;
    }
}

#include <dev/display.h>
#include <lib/gfxconsole.h>

zx_status_t display_get_info(struct display_info* info) {
    return gfxconsole_display_get_info(info);
}

bool platform_early_console_enabled() {
    return !early_console_disabled;
}

static void platform_early_display_init(void) {
    struct display_info info;
    void* bits;

    if (bootloader.fb.base == 0) {
        return;
    }

    if (cmdline_get_bool("gfxconsole.early", false) == false) {
        early_console_disabled = true;
        return;
    }

    // allocate an offscreen buffer of worst-case size, page aligned
    bits = boot_alloc_mem(8192 + bootloader.fb.height * bootloader.fb.stride * 4);
    bits = (void*)((((uintptr_t)bits) + 4095) & (~4095));

    memset(&info, 0, sizeof(info));
    info.format = bootloader.fb.format;
    info.width = bootloader.fb.width;
    info.height = bootloader.fb.height;
    info.stride = bootloader.fb.stride;
    info.flags = DISPLAY_FLAG_HW_FRAMEBUFFER;
    info.framebuffer = (void*)X86_PHYS_TO_VIRT(bootloader.fb.base);

    gfxconsole_bind_display(&info, bits);
}

/* Ensure the framebuffer is write-combining as soon as we have the VMM.
 * Some system firmware has the MTRRs for the framebuffer set to Uncached.
 * Since dealing with MTRRs is rather complicated, we wait for the VMM to
 * come up so we can use PAT to manage the memory types. */
static void platform_ensure_display_memtype(uint level) {
    if (bootloader.fb.base == 0) {
        return;
    }
    if (early_console_disabled) {
        return;
    }
    struct display_info info;
    memset(&info, 0, sizeof(info));
    info.format = bootloader.fb.format;
    info.width = bootloader.fb.width;
    info.height = bootloader.fb.height;
    info.stride = bootloader.fb.stride;
    info.flags = DISPLAY_FLAG_HW_FRAMEBUFFER;

    void* addr = NULL;
    zx_status_t status = VmAspace::kernel_aspace()->AllocPhysical(
        "boot_fb",
        ROUNDUP(info.stride * info.height * 4, PAGE_SIZE),
        &addr,
        PAGE_SIZE_SHIFT,
        bootloader.fb.base,
        0 /* vmm flags */,
        ARCH_MMU_FLAG_WRITE_COMBINING | ARCH_MMU_FLAG_PERM_READ |
            ARCH_MMU_FLAG_PERM_WRITE);
    if (status != ZX_OK) {
        TRACEF("Failed to map boot_fb: %d\n", status);
        return;
    }

    info.framebuffer = addr;
    gfxconsole_bind_display(&info, NULL);
}
LK_INIT_HOOK(display_memtype, &platform_ensure_display_memtype, LK_INIT_LEVEL_VM + 1);

static efi_guid zircon_guid = ZIRCON_VENDOR_GUID;
static char16_t crashlog_name[] = ZIRCON_CRASHLOG_EFIVAR;

static fbl::RefPtr<VmAspace> efi_aspace;

typedef struct {
    uint64_t magic;
    uint64_t length;
    uint64_t nmagic;
    uint64_t nlength;
} log_hdr_t;

#define NVRAM_MAGIC (0x6f8962d66b28504fULL)

static size_t nvram_stow_crashlog(void* log, size_t len) {
    size_t max = bootloader.nvram.length - sizeof(log_hdr_t);
    void* nvram = paddr_to_physmap(bootloader.nvram.base);
    if (nvram == NULL) {
        return 0;
    }

    if (log == NULL) {
        return max;
    }
    if (len > max) {
        len = max;
    }

    log_hdr_t hdr = {
        .magic = NVRAM_MAGIC,
        .length = len,
        .nmagic = ~NVRAM_MAGIC,
        .nlength = ~len,
    };
    memcpy(nvram, &hdr, sizeof(hdr));
    memcpy(static_cast<char*>(nvram) + sizeof(hdr), log, len);
    arch_clean_cache_range((uintptr_t)nvram, sizeof(hdr) + len);
    return len;
}

static size_t nvram_recover_crashlog(size_t len, void* cookie,
                                     void (*func)(const void* data, size_t, size_t len, void* cookie)) {
    size_t max = bootloader.nvram.length - sizeof(log_hdr_t);
    void* nvram = paddr_to_physmap(bootloader.nvram.base);
    if (nvram == NULL) {
        return 0;
    }
    log_hdr_t hdr;
    memcpy(&hdr, nvram, sizeof(hdr));
    if ((hdr.magic != NVRAM_MAGIC) || (hdr.length > max) ||
        (hdr.nmagic != ~NVRAM_MAGIC) || (hdr.nlength != ~hdr.length)) {
        printf("nvram-crashlog: bad header: %016lx %016lx %016lx %016lx\n",
               hdr.magic, hdr.length, hdr.nmagic, hdr.nlength);
        return 0;
    }
    if (len == 0) {
        return hdr.length;
    }
    if (len > hdr.length) {
        len = hdr.length;
    }
    func(static_cast<char*>(nvram) + sizeof(hdr), 0, len, cookie);

    // invalidate header so we don't get a stale crashlog
    // on future boots
    hdr.magic = 0;
    memcpy(nvram, &hdr, sizeof(hdr));
    return hdr.length;
}

void platform_init_crashlog(void) {
    if (bootloader.nvram.base && bootloader.nvram.length > sizeof(log_hdr_t)) {
        // Nothing to do for simple nvram logs
        return;
    } else {
        bootloader.nvram.base = 0;
        bootloader.nvram.length = 0;
    }

    if (bootloader.efi_system_table != NULL) {
        // Create a linear mapping to use to call UEFI Runtime Services
        efi_aspace = VmAspace::Create(VmAspace::TYPE_LOW_KERNEL, "uefi");
        if (!efi_aspace) {
            return;
        }

        //TODO: get more precise about this.  This gets the job done on
        //      the platforms we're working on right now, but is probably
        //      not entirely correct.
        void* ptr = (void*)0;
        zx_status_t r = efi_aspace->AllocPhysical("1:1", 16 * 1024 * 1024 * 1024UL, &ptr,
                                                  PAGE_SIZE_SHIFT, 0,
                                                  VmAspace::VMM_FLAG_VALLOC_SPECIFIC,
                                                  ARCH_MMU_FLAG_PERM_READ |
                                                      ARCH_MMU_FLAG_PERM_WRITE |
                                                      ARCH_MMU_FLAG_PERM_EXECUTE);

        if (r != ZX_OK) {
            efi_aspace.reset();
        }
    }
}

// Something big enough for the panic log but not too enormous
// to avoid excessive pressure on efi variable storage
#define MAX_EFI_CRASHLOG_LEN 4096

static size_t efi_stow_crashlog(void* log, size_t len) {
    if (!efi_aspace) {
        return 0;
    }
    if (log == NULL) {
        return MAX_EFI_CRASHLOG_LEN;
    }
    if (len > MAX_EFI_CRASHLOG_LEN) {
        len = MAX_EFI_CRASHLOG_LEN;
    }

    vmm_set_active_aspace(reinterpret_cast<vmm_aspace_t*>(efi_aspace.get()));

    efi_system_table* sys = static_cast<efi_system_table*>(bootloader.efi_system_table);
    efi_runtime_services* rs = sys->RuntimeServices;
    if (rs->SetVariable(crashlog_name, &zircon_guid, ZIRCON_CRASHLOG_EFIATTR, len, log) == 0) {
        return len;
    } else {
        return 0;
    }
}

size_t platform_stow_crashlog(void* log, size_t len) {
    if (bootloader.nvram.base) {
        return nvram_stow_crashlog(log, len);
    } else {
        return efi_stow_crashlog(log, len);
    }
}

size_t platform_recover_crashlog(size_t len, void* cookie,
                                 void (*func)(const void* data, size_t, size_t len, void* cookie)) {
    if (bootloader.nvram.base != 0) {
        return nvram_recover_crashlog(len, cookie, func);
    } else if (last_crashlog != nullptr) {
        if (len != 0) {
            func(last_crashlog, 0, last_crashlog_len, cookie);
        }
        return last_crashlog_len;
    }
    return 0;
}

typedef struct e820_walk_ctx {
    uint8_t* buf;
    size_t len;
    zx_status_t ret;
} e820_walk_ctx_t;

static void e820_entry_walk(uint64_t base, uint64_t size, bool is_mem, void* void_ctx) {
    e820_walk_ctx* ctx = (e820_walk_ctx*)void_ctx;

    // Something went wrong in one of the previous calls, don't attempt to
    // continue.
    if (ctx->ret != ZX_OK)
        return;

    // Make sure we have enough space in the buffer.
    if (ctx->len < sizeof(e820entry_t)) {
        ctx->ret = ZX_ERR_BUFFER_TOO_SMALL;
        return;
    }

    e820entry_t* entry = (e820entry_t*)ctx->buf;
    entry->addr = base;
    entry->size = size;

    // Hack: When we first parse this map we normalize each section to either
    // memory or not-memory. When we pass it to the next kernel, we lose
    // information about the type of "not memory" in each region.
    entry->type = is_mem ? E820_RAM : E820_RESERVED;

    ctx->buf += sizeof(*entry);
    ctx->len -= sizeof(*entry);
    ctx->ret = ZX_OK;
}

// Give the platform an opportunity to append any platform specific bootdata
// sections.
zx_status_t platform_mexec_patch_zbi(uint8_t* bootdata, const size_t len) {
    uint8_t e820buf[sizeof(e820entry_t) * 32];

    e820_walk_ctx ctx;
    ctx.buf = e820buf;
    ctx.len = sizeof(e820buf);
    ctx.ret = ZX_OK;

    zx_status_t ret = enumerate_e820(e820_entry_walk, &ctx);

    if (ret != ZX_OK) {
        printf("mexec: enumerate_e820 failed. Retcode = %d\n", ret);
        return ret;
    }

    if (ctx.ret != ZX_OK) {
        printf("mexec: error while enumerating e820 map. Retcode = %d\n",
               ctx.ret);
        return ctx.ret;
    }

    zbi::Zbi image(bootdata, len);
    zbi_result_t result;

    const uint32_t kNoZbiFlags = 0;
    const uint32_t kNoZbiExtra = 0;

    uint32_t section_length = (uint32_t)(sizeof(e820buf) - ctx.len);
    result = image.AppendSection(section_length, ZBI_TYPE_E820_TABLE,
                                 kNoZbiExtra, kNoZbiFlags, e820buf);

    if (result != ZBI_RESULT_OK) {
        printf("mexec: Failed to append e820 map to zbi. len = %lu, section "
               "length = %u, retcode = %d\n", len, section_length, result);
        return ZX_ERR_INTERNAL;
    }

    // Append information about the framebuffer to the bootdata
    if (bootloader.fb.base) {
        result = image.AppendSection(sizeof(bootloader.fb),
                                     ZBI_TYPE_FRAMEBUFFER, kNoZbiExtra,
                                     kNoZbiFlags,(uint8_t*)&bootloader.fb);
        if (result != ZBI_RESULT_OK) {
            printf("mexec: Failed to append framebuffer data to bootdata. "
                   "len = %lu, section length = %lu, retcode = %d\n", len,
                   sizeof(bootloader.fb), result);
            return ZX_ERR_INTERNAL;
        }
    }

    if (bootloader.efi_system_table) {
        result = image.AppendSection(sizeof(bootloader.efi_system_table),
                                     ZBI_TYPE_EFI_SYSTEM_TABLE, kNoZbiExtra,
                                     kNoZbiFlags,
                                     (uint8_t*)&bootloader.efi_system_table);
        if (result != ZBI_RESULT_OK) {
            printf("mexec: Failed to append efi sys table data to bootdata. "
                   "len = %lu, section length = %lu, retcode = %d\n", len,
                   sizeof(bootloader.efi_system_table), result);
            return ZX_ERR_INTERNAL;
        }
    }

    if (bootloader.acpi_rsdp) {
        result = image.AppendSection(sizeof(bootloader.acpi_rsdp),
                                     ZBI_TYPE_ACPI_RSDP, kNoZbiExtra,
                                     kNoZbiFlags,
                                     (uint8_t*)&bootloader.acpi_rsdp);
        if (result != ZBI_RESULT_OK) {
            printf("mexec: Failed to append acpi rsdp data to bootdata. "
                   "len = %lu, section length = %lu, retcode = %d\n", len,
                   sizeof(bootloader.acpi_rsdp), result);
            return ZX_ERR_INTERNAL;
        }
    }

    if (bootloader.smbios) {
        result = image.AppendSection(sizeof(bootloader.smbios), ZBI_TYPE_SMBIOS,
                                     kNoZbiExtra, kNoZbiFlags,
                                     (uint8_t*)&bootloader.smbios);
        if (result != ZBI_RESULT_OK) {
            printf("mexec: Failed to append smbios data to bootdata. len = %lu,"
                   " section length = %lu, retcode = %d\n", len,
                   sizeof(bootloader.smbios), result);
            return ZX_ERR_INTERNAL;
        }
    }

    if (bootloader.uart.type != ZBI_UART_NONE) {
        result = image.AppendSection(sizeof(bootloader.uart),
                                     ZBI_TYPE_DEBUG_UART, kNoZbiExtra,
                                     kNoZbiFlags, (uint8_t*)&bootloader.uart);
        if (result != ZBI_RESULT_OK) {
            printf("mexec: Failed to append uart data to bootdata. len = %lu, "
                   "section length = %lu, retcode = %d\n", len,
                   sizeof(bootloader.uart), result);
            return ZX_ERR_INTERNAL;
        }
    }

    if (bootloader.nvram.base) {
        result = image.AppendSection(sizeof(bootloader.nvram),
                                     ZBI_TYPE_NVRAM, kNoZbiExtra,
                                     kNoZbiFlags, (uint8_t*)&bootloader.nvram);

        if (result != ZBI_RESULT_OK) {
            printf("mexec: Failed to append nvram data to bootdata. len = %lu, "
                   "section length = %lu, retcode = %d\n", len,
                   sizeof(bootloader.nvram), result);
            return ZX_ERR_INTERNAL;
        }
    }

    return ZX_OK;
}

// Number of pages required to identity map 4GiB of memory.
const size_t kBytesToIdentityMap = 4ull * GB;
const size_t kNumL2PageTables = kBytesToIdentityMap / (2ull * MB * NO_OF_PT_ENTRIES);
const size_t kNumL3PageTables = 1;
const size_t kNumL4PageTables = 1;
const size_t kTotalPageTableCount = kNumL2PageTables + kNumL3PageTables + kNumL4PageTables;

// Allocate `count` pages where no page has a physical address less than
// `lower_bound`
static void alloc_pages_greater_than(paddr_t lower_bound, size_t count, paddr_t* paddrs) {
    struct list_node list = LIST_INITIAL_VALUE(list);
    while (count) {
        // TODO: replace with pmm routine that can allocate not in a range
        size_t actual = 0;
        zx_status_t status = pmm_alloc_range(lower_bound, count, &list);
        if (status == ZX_OK) {
            actual = count;
        }

        for (size_t i = 0; i < actual; i++) {
            paddrs[count - (i + 1)] = lower_bound + PAGE_SIZE * i;
        }

        count -= actual;
        lower_bound += PAGE_SIZE * (actual + 1);

        // If we're past the 4GiB mark and still trying to allocate, just give
        // up.
        if (lower_bound >= (4 * GB)) {
            panic("failed to allocate page tables for mexec");
        }
    }

    // mark all of the pages we allocated as WIRED
    vm_page_t* p;
    list_for_every_entry (&list, p, vm_page_t, queue_node) {
        p->state = VM_PAGE_STATE_WIRED;
    }
}

static fbl::RefPtr<VmAspace> mexec_identity_aspace;

// Array of pages that are safe to use for the new kernel's page tables.  These must
// be after where the new boot image will be placed during mexec.  This array is
// populated in platform_mexec_prep and used in platform_mexec.
static paddr_t mexec_safe_pages[kTotalPageTableCount];

void platform_mexec_prep(uintptr_t new_bootimage_addr, size_t new_bootimage_len) {
    DEBUG_ASSERT(!arch_ints_disabled());
    DEBUG_ASSERT(mp_get_online_mask() == cpu_num_to_mask(BOOT_CPU_ID));

    // A hacky way to handle disabling all PCI devices until we have devhost
    // lifecycles implemented.
    // Leaving PCI running will also leave DMA running which may cause memory
    // corruption after boot.
    // Disabling PCI may cause devices to fail to enumerate after boot.
#ifdef WITH_KERNEL_PCIE
    if (cmdline_get_bool("kernel.mexec-pci-shutdown", true)) {
        PcieBusDriver::GetDriver()->DisableBus();
    }
#endif

    // This code only handles one L3 and one L4 page table for now. Fail if
    // there are more L2 page tables than can fit in one L3 page table.
    static_assert(kNumL2PageTables <= NO_OF_PT_ENTRIES,
                  "Kexec identity map size is too large. Only one L3 PTE is supported at this time.");
    static_assert(kNumL3PageTables == 1, "Only 1 L3 page table is supported at this time.");
    static_assert(kNumL4PageTables == 1, "Only 1 L4 page table is supported at this time.");

    // Identity map the first 4GiB of RAM
    mexec_identity_aspace =
        VmAspace::Create(VmAspace::TYPE_LOW_KERNEL, "x86-64 mexec 1:1");
    DEBUG_ASSERT(mexec_identity_aspace);

    const uint perm_flags_rwx = ARCH_MMU_FLAG_PERM_READ |
                                ARCH_MMU_FLAG_PERM_WRITE |
                                ARCH_MMU_FLAG_PERM_EXECUTE;
    void* identity_address = 0x0;
    paddr_t pa = 0;
    zx_status_t result = mexec_identity_aspace->AllocPhysical("1:1 mapping", kBytesToIdentityMap,
                                                              &identity_address, 0, pa,
                                                              VmAspace::VMM_FLAG_VALLOC_SPECIFIC,
                                                              perm_flags_rwx);
    if (result != ZX_OK) {
        panic("failed to identity map low memory");
    }

    alloc_pages_greater_than(new_bootimage_addr + new_bootimage_len + PAGE_SIZE,
                             kTotalPageTableCount, mexec_safe_pages);
}

void platform_mexec(mexec_asm_func mexec_assembly, memmov_ops_t* ops,
                    uintptr_t new_bootimage_addr, size_t new_bootimage_len,
                    uintptr_t entry64_addr) {
    DEBUG_ASSERT(arch_ints_disabled());
    DEBUG_ASSERT(mp_get_online_mask() == cpu_num_to_mask(BOOT_CPU_ID));

    // This code only handles one L3 and one L4 page table for now. Fail if
    // there are more L2 page tables than can fit in one L3 page table.
    static_assert(kNumL2PageTables <= NO_OF_PT_ENTRIES,
                  "Kexec identity map size is too large. Only one L3 PTE is supported at this time.");
    static_assert(kNumL3PageTables == 1, "Only 1 L3 page table is supported at this time.");
    static_assert(kNumL4PageTables == 1, "Only 1 L4 page table is supported at this time.");
    DEBUG_ASSERT(mexec_identity_aspace);

    vmm_set_active_aspace(reinterpret_cast<vmm_aspace_t*>(mexec_identity_aspace.get()));

    size_t safe_page_id = 0;
    volatile pt_entry_t* ptl4 = (pt_entry_t*)paddr_to_physmap(mexec_safe_pages[safe_page_id++]);
    volatile pt_entry_t* ptl3 = (pt_entry_t*)paddr_to_physmap(mexec_safe_pages[safe_page_id++]);

    // Initialize these to 0
    for (size_t i = 0; i < NO_OF_PT_ENTRIES; i++) {
        ptl4[i] = 0;
        ptl3[i] = 0;
    }

    for (size_t i = 0; i < kNumL2PageTables; i++) {
        ptl3[i] = mexec_safe_pages[safe_page_id] | X86_KERNEL_PD_FLAGS;
        volatile pt_entry_t* ptl2 = (pt_entry_t*)paddr_to_physmap(mexec_safe_pages[safe_page_id]);

        for (size_t j = 0; j < NO_OF_PT_ENTRIES; j++) {
            ptl2[j] = (2 * MB * (i * NO_OF_PT_ENTRIES + j)) | X86_KERNEL_PD_LP_FLAGS;
        }

        safe_page_id++;
    }

    ptl4[0] = vaddr_to_paddr((void*)ptl3) | X86_KERNEL_PD_FLAGS;

    mexec_assembly((uintptr_t)new_bootimage_addr, vaddr_to_paddr((void*)ptl4),
                   entry64_addr, 0, ops, 0);
}

void platform_halt_secondary_cpus(void) {
    // Ensure the current thread is pinned to the boot CPU.
    DEBUG_ASSERT(get_current_thread()->cpu_affinity == cpu_num_to_mask(BOOT_CPU_ID));

    // "Unplug" online secondary CPUs before halting them.
    cpu_mask_t primary = cpu_num_to_mask(BOOT_CPU_ID);
    cpu_mask_t mask = mp_get_online_mask() & ~primary;
    zx_status_t result = mp_unplug_cpu_mask(mask);
    DEBUG_ASSERT(result == ZX_OK);
}

void platform_early_init(void) {
    /* call before bootloader data is populated, since we want to
     * let the bootloader data override this */
    pc_init_debug_default_early();

    /* extract bootloader data while still accessible */
    /* this includes debug uart config, etc. */
    platform_save_bootloader_data();

    /* is the cmdline option to bypass dlog set ? */
    dlog_bypass_init();

    /* get the debug output working */
    pc_init_debug_early();

#if WITH_LEGACY_PC_CONSOLE
    /* get the text console working */
    platform_init_console();
#endif

    /* if the bootloader has framebuffer info, use it for early console */
    platform_early_display_init();

    /* initialize the boot memory reservation system */
    boot_reserve_init();

    /* add the ramdisk to the boot reserve list */
    platform_preserve_ramdisk();

    /* initialize physical memory arenas */
    pc_mem_init();

    /* wire all of the reserved boot sections */
    boot_reserve_wire();
}

static void platform_init_smp(void) {
    uint32_t num_cpus = 0;

    zx_status_t status = platform_enumerate_cpus(NULL, 0, &num_cpus);
    if (status != ZX_OK) {
        TRACEF("failed to enumerate CPUs, disabling SMP\n");
        return;
    }

    // allocate 2x the table for temporary work
    fbl::AllocChecker ac;
    ktl::unique_ptr<uint32_t[]> apic_ids =
        ktl::unique_ptr<uint32_t[]>(new (&ac) uint32_t[num_cpus * 2]);
    if (!ac.check()) {
        TRACEF("failed to allocate apic_ids table, disabling SMP\n");
        return;
    }

    // a temporary list used before we filter out hyperthreaded pairs
    uint32_t* apic_ids_temp = &apic_ids[num_cpus];

    // find the list of all cpu apic ids into a temporary list
    uint32_t real_num_cpus;
    status = platform_enumerate_cpus(apic_ids_temp, num_cpus, &real_num_cpus);
    if (status != ZX_OK || num_cpus != real_num_cpus) {
        TRACEF("failed to enumerate CPUs, disabling SMP\n");
        return;
    }

    // Filter out hyperthreads if we've been told not to init them
    bool use_ht = cmdline_get_bool("kernel.smp.ht", true);

    // we're implicitly running on the BSP
    uint32_t bsp_apic_id = apic_local_id();
    DEBUG_ASSERT(bsp_apic_id == apic_bsp_id());

    // iterate over all the cores and optionally disable some of them
    dprintf(INFO, "cpu topology:\n");
    uint32_t using_count = 0;
    for (uint32_t i = 0; i < num_cpus; ++i) {
        x86_cpu_topology_t topo;
        x86_cpu_topology_decode(apic_ids_temp[i], &topo);

        // filter it out if it's a HT pair that we dont want to use
        bool keep = true;
        if (!use_ht && topo.smt_id != 0)
            keep = false;

        dprintf(INFO, "\t%u: apic id 0x%x package %u node %u core %u smt %u%s%s\n",
                i, apic_ids_temp[i], topo.package_id, topo.node_id, topo.core_id, topo.smt_id,
                (apic_ids_temp[i] == bsp_apic_id) ? " BSP" : "",
                keep ? "" : " (not using)");

        if (!keep)
            continue;

        // save this apic id into the primary list
        apic_ids[using_count++] = apic_ids_temp[i];
    }
    num_cpus = using_count;

    // Find the CPU count limit
    uint32_t max_cpus = cmdline_get_uint32("kernel.smp.maxcpus", SMP_MAX_CPUS);
    if (max_cpus > SMP_MAX_CPUS || max_cpus <= 0) {
        printf("invalid kernel.smp.maxcpus value, defaulting to %d\n", SMP_MAX_CPUS);
        max_cpus = SMP_MAX_CPUS;
    }

    dprintf(INFO, "Found %u cpu%c\n", num_cpus, (num_cpus > 1) ? 's' : ' ');
    if (num_cpus > max_cpus) {
        dprintf(INFO, "Clamping number of CPUs to %u\n", max_cpus);
        num_cpus = max_cpus;
    }

    if (num_cpus == max_cpus || !use_ht) {
        // If we are at the max number of CPUs, or have filtered out
        // hyperthreads, sanity check that the bootstrap processor is in the set.
        bool found_bp = false;
        for (unsigned int i = 0; i < num_cpus; ++i) {
            if (apic_ids[i] == bsp_apic_id) {
                found_bp = true;
                break;
            }
        }
        ASSERT(found_bp);
    }

    x86_init_smp(apic_ids.get(), num_cpus);

    // trim the boot cpu out of the apic id list before passing to the AP booting routine
    for (uint i = 0; i < num_cpus - 1; ++i) {
        if (apic_ids[i] == bsp_apic_id) {
            memmove(&apic_ids[i], &apic_ids[i + 1], sizeof(apic_ids[0]) * (num_cpus - i - 1));
            break;
        }
    }

    x86_bringup_aps(apic_ids.get(), num_cpus - 1);
}

zx_status_t platform_mp_prep_cpu_unplug(uint cpu_id) {
    // TODO: Make sure the IOAPIC and PCI have nothing for this CPU
    return arch_mp_prep_cpu_unplug(cpu_id);
}

const char* manufacturer = "unknown";
const char* product = "unknown";

void platform_init(void) {
    pc_init_debug();

    platform_init_crashlog();

#if NO_USER_KEYBOARD
    platform_init_keyboard(&console_input_buf);
#endif

    platform_init_smp();

    pc_init_smbios();

    SmbiosWalkStructs([](smbios::SpecVersion version, const smbios::Header* h,
                         const smbios::StringTable& st, void* ctx) -> zx_status_t {
        if (h->type == smbios::StructType::SystemInfo && version.IncludesVersion(2, 0)) {
            auto entry = reinterpret_cast<const smbios::SystemInformationStruct2_0*>(h);
            st.GetString(entry->manufacturer_str_idx, &manufacturer);
            st.GetString(entry->product_name_str_idx, &product);
        }
        return ZX_OK;
    }, nullptr);
    printf("smbios: manufacturer=\"%s\" product=\"%s\"\n", manufacturer, product);
}

void platform_suspend(void) {
    pc_prep_suspend_timer();
    pc_suspend_debug();
}

void platform_resume(void) {
    pc_resume_debug();
    pc_resume_timer();
}