x86/efi: Enforce CONFIG_RELOCATABLE for EFI boot stub

[linux/fpc-iii.git] / arch / x86 / kernel / microcode_intel_early.c

/*
 *      Intel CPU microcode early update for Linux
 *
 *      Copyright (C) 2012 Fenghua Yu <fenghua.yu@intel.com>
 *                         H Peter Anvin" <hpa@zytor.com>
 *
 *      This allows to early upgrade microcode on Intel processors
 *      belonging to IA-32 family - PentiumPro, Pentium II,
 *      Pentium III, Xeon, Pentium 4, etc.
 *
 *      Reference: Section 9.11 of Volume 3, IA-32 Intel Architecture
 *      Software Developer's Manual.
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 */
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/earlycpio.h>
#include <linux/initrd.h>
#include <linux/cpu.h>
#include <asm/msr.h>
#include <asm/microcode_intel.h>
#include <asm/processor.h>
#include <asm/tlbflush.h>
#include <asm/setup.h>

unsigned long mc_saved_in_initrd[MAX_UCODE_COUNT];
struct mc_saved_data {
        unsigned int mc_saved_count;
        struct microcode_intel **mc_saved;
} mc_saved_data;

static enum ucode_state
generic_load_microcode_early(struct microcode_intel **mc_saved_p,
                             unsigned int mc_saved_count,
                             struct ucode_cpu_info *uci)
{
        struct microcode_intel *ucode_ptr, *new_mc = NULL;
        int new_rev = uci->cpu_sig.rev;
        enum ucode_state state = UCODE_OK;
        unsigned int mc_size;
        struct microcode_header_intel *mc_header;
        unsigned int csig = uci->cpu_sig.sig;
        unsigned int cpf = uci->cpu_sig.pf;
        int i;

        for (i = 0; i < mc_saved_count; i++) {
                ucode_ptr = mc_saved_p[i];

                mc_header = (struct microcode_header_intel *)ucode_ptr;
                mc_size = get_totalsize(mc_header);
                if (get_matching_microcode(csig, cpf, ucode_ptr, new_rev)) {
                        new_rev = mc_header->rev;
                        new_mc  = ucode_ptr;
                }
        }

        if (!new_mc) {
                state = UCODE_NFOUND;
                goto out;
        }

        uci->mc = (struct microcode_intel *)new_mc;
out:
        return state;
}

static void
microcode_pointer(struct microcode_intel **mc_saved,
                  unsigned long *mc_saved_in_initrd,
                  unsigned long initrd_start, int mc_saved_count)
{
        int i;

        for (i = 0; i < mc_saved_count; i++)
                mc_saved[i] = (struct microcode_intel *)
                              (mc_saved_in_initrd[i] + initrd_start);
}

#ifdef CONFIG_X86_32
static void
microcode_phys(struct microcode_intel **mc_saved_tmp,
               struct mc_saved_data *mc_saved_data)
{
        int i;
        struct microcode_intel ***mc_saved;

        mc_saved = (struct microcode_intel ***)
                   __pa_nodebug(&mc_saved_data->mc_saved);
        for (i = 0; i < mc_saved_data->mc_saved_count; i++) {
                struct microcode_intel *p;

                p = *(struct microcode_intel **)
                        __pa_nodebug(mc_saved_data->mc_saved + i);
                mc_saved_tmp[i] = (struct microcode_intel *)__pa_nodebug(p);
        }
}
#endif

static enum ucode_state
load_microcode(struct mc_saved_data *mc_saved_data,
               unsigned long *mc_saved_in_initrd,
               unsigned long initrd_start,
               struct ucode_cpu_info *uci)
{
        struct microcode_intel *mc_saved_tmp[MAX_UCODE_COUNT];
        unsigned int count = mc_saved_data->mc_saved_count;

        if (!mc_saved_data->mc_saved) {
                microcode_pointer(mc_saved_tmp, mc_saved_in_initrd,
                                  initrd_start, count);

                return generic_load_microcode_early(mc_saved_tmp, count, uci);
        } else {
#ifdef CONFIG_X86_32
                microcode_phys(mc_saved_tmp, mc_saved_data);
                return generic_load_microcode_early(mc_saved_tmp, count, uci);
#else
                return generic_load_microcode_early(mc_saved_data->mc_saved,
                                                    count, uci);
#endif
        }
}

static u8 get_x86_family(unsigned long sig)
{
        u8 x86;

        x86 = (sig >> 8) & 0xf;

        if (x86 == 0xf)
                x86 += (sig >> 20) & 0xff;

        return x86;
}

static u8 get_x86_model(unsigned long sig)
{
        u8 x86, x86_model;

        x86 = get_x86_family(sig);
        x86_model = (sig >> 4) & 0xf;

        if (x86 == 0x6 || x86 == 0xf)
                x86_model += ((sig >> 16) & 0xf) << 4;

        return x86_model;
}

/*
 * Given CPU signature and a microcode patch, this function finds if the
 * microcode patch has matching family and model with the CPU.
 */
static enum ucode_state
matching_model_microcode(struct microcode_header_intel *mc_header,
                        unsigned long sig)
{
        u8 x86, x86_model;
        u8 x86_ucode, x86_model_ucode;
        struct extended_sigtable *ext_header;
        unsigned long total_size = get_totalsize(mc_header);
        unsigned long data_size = get_datasize(mc_header);
        int ext_sigcount, i;
        struct extended_signature *ext_sig;

        x86 = get_x86_family(sig);
        x86_model = get_x86_model(sig);

        x86_ucode = get_x86_family(mc_header->sig);
        x86_model_ucode = get_x86_model(mc_header->sig);

        if (x86 == x86_ucode && x86_model == x86_model_ucode)
                return UCODE_OK;

        /* Look for ext. headers: */
        if (total_size <= data_size + MC_HEADER_SIZE)
                return UCODE_NFOUND;

        ext_header = (struct extended_sigtable *)
                     mc_header + data_size + MC_HEADER_SIZE;
        ext_sigcount = ext_header->count;
        ext_sig = (void *)ext_header + EXT_HEADER_SIZE;

        for (i = 0; i < ext_sigcount; i++) {
                x86_ucode = get_x86_family(ext_sig->sig);
                x86_model_ucode = get_x86_model(ext_sig->sig);

                if (x86 == x86_ucode && x86_model == x86_model_ucode)
                        return UCODE_OK;

                ext_sig++;
        }

        return UCODE_NFOUND;
}

static int
save_microcode(struct mc_saved_data *mc_saved_data,
               struct microcode_intel **mc_saved_src,
               unsigned int mc_saved_count)
{
        int i, j;
        struct microcode_intel **mc_saved_p;
        int ret;

        if (!mc_saved_count)
                return -EINVAL;

        /*
         * Copy new microcode data.
         */
        mc_saved_p = kmalloc(mc_saved_count*sizeof(struct microcode_intel *),
                             GFP_KERNEL);
        if (!mc_saved_p)
                return -ENOMEM;

        for (i = 0; i < mc_saved_count; i++) {
                struct microcode_intel *mc = mc_saved_src[i];
                struct microcode_header_intel *mc_header = &mc->hdr;
                unsigned long mc_size = get_totalsize(mc_header);
                mc_saved_p[i] = kmalloc(mc_size, GFP_KERNEL);
                if (!mc_saved_p[i]) {
                        ret = -ENOMEM;
                        goto err;
                }
                if (!mc_saved_src[i]) {
                        ret = -EINVAL;
                        goto err;
                }
                memcpy(mc_saved_p[i], mc, mc_size);
        }

        /*
         * Point to newly saved microcode.
         */
        mc_saved_data->mc_saved = mc_saved_p;
        mc_saved_data->mc_saved_count = mc_saved_count;

        return 0;

err:
        for (j = 0; j <= i; j++)
                kfree(mc_saved_p[j]);
        kfree(mc_saved_p);

        return ret;
}

/*
 * A microcode patch in ucode_ptr is saved into mc_saved
 * - if it has matching signature and newer revision compared to an existing
 *   patch mc_saved.
 * - or if it is a newly discovered microcode patch.
 *
 * The microcode patch should have matching model with CPU.
 */
static void _save_mc(struct microcode_intel **mc_saved, u8 *ucode_ptr,
                     unsigned int *mc_saved_count_p)
{
        int i;
        int found = 0;
        unsigned int mc_saved_count = *mc_saved_count_p;
        struct microcode_header_intel *mc_header;

        mc_header = (struct microcode_header_intel *)ucode_ptr;
        for (i = 0; i < mc_saved_count; i++) {
                unsigned int sig, pf;
                unsigned int new_rev;
                struct microcode_header_intel *mc_saved_header =
                             (struct microcode_header_intel *)mc_saved[i];
                sig = mc_saved_header->sig;
                pf = mc_saved_header->pf;
                new_rev = mc_header->rev;

                if (get_matching_sig(sig, pf, ucode_ptr, new_rev)) {
                        found = 1;
                        if (update_match_revision(mc_header, new_rev)) {
                                /*
                                 * Found an older ucode saved before.
                                 * Replace the older one with this newer
                                 * one.
                                 */
                                mc_saved[i] =
                                        (struct microcode_intel *)ucode_ptr;
                                break;
                        }
                }
        }
        if (i >= mc_saved_count && !found)
                /*
                 * This ucode is first time discovered in ucode file.
                 * Save it to memory.
                 */
                mc_saved[mc_saved_count++] =
                                 (struct microcode_intel *)ucode_ptr;

        *mc_saved_count_p = mc_saved_count;
}

/*
 * Get microcode matching with BSP's model. Only CPUs with the same model as
 * BSP can stay in the platform.
 */
static enum ucode_state __init
get_matching_model_microcode(int cpu, unsigned long start,
                             void *data, size_t size,
                             struct mc_saved_data *mc_saved_data,
                             unsigned long *mc_saved_in_initrd,
                             struct ucode_cpu_info *uci)
{
        u8 *ucode_ptr = data;
        unsigned int leftover = size;
        enum ucode_state state = UCODE_OK;
        unsigned int mc_size;
        struct microcode_header_intel *mc_header;
        struct microcode_intel *mc_saved_tmp[MAX_UCODE_COUNT];
        unsigned int mc_saved_count = mc_saved_data->mc_saved_count;
        int i;

        while (leftover) {
                mc_header = (struct microcode_header_intel *)ucode_ptr;

                mc_size = get_totalsize(mc_header);
                if (!mc_size || mc_size > leftover ||
                        microcode_sanity_check(ucode_ptr, 0) < 0)
                        break;

                leftover -= mc_size;

                /*
                 * Since APs with same family and model as the BSP may boot in
                 * the platform, we need to find and save microcode patches
                 * with the same family and model as the BSP.
                 */
                if (matching_model_microcode(mc_header, uci->cpu_sig.sig) !=
                         UCODE_OK) {
                        ucode_ptr += mc_size;
                        continue;
                }

                _save_mc(mc_saved_tmp, ucode_ptr, &mc_saved_count);

                ucode_ptr += mc_size;
        }

        if (leftover) {
                state = UCODE_ERROR;
                goto out;
        }

        if (mc_saved_count == 0) {
                state = UCODE_NFOUND;
                goto out;
        }

        for (i = 0; i < mc_saved_count; i++)
                mc_saved_in_initrd[i] = (unsigned long)mc_saved_tmp[i] - start;

        mc_saved_data->mc_saved_count = mc_saved_count;
out:
        return state;
}

#define native_rdmsr(msr, val1, val2)           \
do {                                            \
        u64 __val = native_read_msr((msr));     \
        (void)((val1) = (u32)__val);            \
        (void)((val2) = (u32)(__val >> 32));    \
} while (0)

#define native_wrmsr(msr, low, high)            \
        native_write_msr(msr, low, high);

static int collect_cpu_info_early(struct ucode_cpu_info *uci)
{
        unsigned int val[2];
        u8 x86, x86_model;
        struct cpu_signature csig;
        unsigned int eax, ebx, ecx, edx;

        csig.sig = 0;
        csig.pf = 0;
        csig.rev = 0;

        memset(uci, 0, sizeof(*uci));

        eax = 0x00000001;
        ecx = 0;
        native_cpuid(&eax, &ebx, &ecx, &edx);
        csig.sig = eax;

        x86 = get_x86_family(csig.sig);
        x86_model = get_x86_model(csig.sig);

        if ((x86_model >= 5) || (x86 > 6)) {
                /* get processor flags from MSR 0x17 */
                native_rdmsr(MSR_IA32_PLATFORM_ID, val[0], val[1]);
                csig.pf = 1 << ((val[1] >> 18) & 7);
        }
        native_wrmsr(MSR_IA32_UCODE_REV, 0, 0);

        /* As documented in the SDM: Do a CPUID 1 here */
        sync_core();

        /* get the current revision from MSR 0x8B */
        native_rdmsr(MSR_IA32_UCODE_REV, val[0], val[1]);

        csig.rev = val[1];

        uci->cpu_sig = csig;
        uci->valid = 1;

        return 0;
}

#ifdef DEBUG
static void __ref show_saved_mc(void)
{
        int i, j;
        unsigned int sig, pf, rev, total_size, data_size, date;
        struct ucode_cpu_info uci;

        if (mc_saved_data.mc_saved_count == 0) {
                pr_debug("no micorcode data saved.\n");
                return;
        }
        pr_debug("Total microcode saved: %d\n", mc_saved_data.mc_saved_count);

        collect_cpu_info_early(&uci);

        sig = uci.cpu_sig.sig;
        pf = uci.cpu_sig.pf;
        rev = uci.cpu_sig.rev;
        pr_debug("CPU%d: sig=0x%x, pf=0x%x, rev=0x%x\n",
                 smp_processor_id(), sig, pf, rev);

        for (i = 0; i < mc_saved_data.mc_saved_count; i++) {
                struct microcode_header_intel *mc_saved_header;
                struct extended_sigtable *ext_header;
                int ext_sigcount;
                struct extended_signature *ext_sig;

                mc_saved_header = (struct microcode_header_intel *)
                                  mc_saved_data.mc_saved[i];
                sig = mc_saved_header->sig;
                pf = mc_saved_header->pf;
                rev = mc_saved_header->rev;
                total_size = get_totalsize(mc_saved_header);
                data_size = get_datasize(mc_saved_header);
                date = mc_saved_header->date;

                pr_debug("mc_saved[%d]: sig=0x%x, pf=0x%x, rev=0x%x, toal size=0x%x, date = %04x-%02x-%02x\n",
                         i, sig, pf, rev, total_size,
                         date & 0xffff,
                         date >> 24,
                         (date >> 16) & 0xff);

                /* Look for ext. headers: */
                if (total_size <= data_size + MC_HEADER_SIZE)
                        continue;

                ext_header = (struct extended_sigtable *)
                             mc_saved_header + data_size + MC_HEADER_SIZE;
                ext_sigcount = ext_header->count;
                ext_sig = (void *)ext_header + EXT_HEADER_SIZE;

                for (j = 0; j < ext_sigcount; j++) {
                        sig = ext_sig->sig;
                        pf = ext_sig->pf;

                        pr_debug("\tExtended[%d]: sig=0x%x, pf=0x%x\n",
                                 j, sig, pf);

                        ext_sig++;
                }

        }
}
#else
static inline void show_saved_mc(void)
{
}
#endif

#if defined(CONFIG_MICROCODE_INTEL_EARLY) && defined(CONFIG_HOTPLUG_CPU)
static DEFINE_MUTEX(x86_cpu_microcode_mutex);
/*
 * Save this mc into mc_saved_data. So it will be loaded early when a CPU is
 * hot added or resumes.
 *
 * Please make sure this mc should be a valid microcode patch before calling
 * this function.
 */
int save_mc_for_early(u8 *mc)
{
        struct microcode_intel *mc_saved_tmp[MAX_UCODE_COUNT];
        unsigned int mc_saved_count_init;
        unsigned int mc_saved_count;
        struct microcode_intel **mc_saved;
        int ret = 0;
        int i;

        /*
         * Hold hotplug lock so mc_saved_data is not accessed by a CPU in
         * hotplug.
         */
        mutex_lock(&x86_cpu_microcode_mutex);

        mc_saved_count_init = mc_saved_data.mc_saved_count;
        mc_saved_count = mc_saved_data.mc_saved_count;
        mc_saved = mc_saved_data.mc_saved;

        if (mc_saved && mc_saved_count)
                memcpy(mc_saved_tmp, mc_saved,
                       mc_saved_count * sizeof(struct mirocode_intel *));
        /*
         * Save the microcode patch mc in mc_save_tmp structure if it's a newer
         * version.
         */

        _save_mc(mc_saved_tmp, mc, &mc_saved_count);

        /*
         * Save the mc_save_tmp in global mc_saved_data.
         */
        ret = save_microcode(&mc_saved_data, mc_saved_tmp, mc_saved_count);
        if (ret) {
                pr_err("Cannot save microcode patch.\n");
                goto out;
        }

        show_saved_mc();

        /*
         * Free old saved microcod data.
         */
        if (mc_saved) {
                for (i = 0; i < mc_saved_count_init; i++)
                        kfree(mc_saved[i]);
                kfree(mc_saved);
        }

out:
        mutex_unlock(&x86_cpu_microcode_mutex);

        return ret;
}
EXPORT_SYMBOL_GPL(save_mc_for_early);
#endif

static __initdata char ucode_name[] = "kernel/x86/microcode/GenuineIntel.bin";
static __init enum ucode_state
scan_microcode(unsigned long start, unsigned long end,
                struct mc_saved_data *mc_saved_data,
                unsigned long *mc_saved_in_initrd,
                struct ucode_cpu_info *uci)
{
        unsigned int size = end - start + 1;
        struct cpio_data cd;
        long offset = 0;
#ifdef CONFIG_X86_32
        char *p = (char *)__pa_nodebug(ucode_name);
#else
        char *p = ucode_name;
#endif

        cd.data = NULL;
        cd.size = 0;

        cd = find_cpio_data(p, (void *)start, size, &offset);
        if (!cd.data)
                return UCODE_ERROR;


        return get_matching_model_microcode(0, start, cd.data, cd.size,
                                            mc_saved_data, mc_saved_in_initrd,
                                            uci);
}

/*
 * Print ucode update info.
 */
static void
print_ucode_info(struct ucode_cpu_info *uci, unsigned int date)
{
        int cpu = smp_processor_id();

        pr_info("CPU%d microcode updated early to revision 0x%x, date = %04x-%02x-%02x\n",
                cpu,
                uci->cpu_sig.rev,
                date & 0xffff,
                date >> 24,
                (date >> 16) & 0xff);
}

#ifdef CONFIG_X86_32

static int delay_ucode_info;
static int current_mc_date;

/*
 * Print early updated ucode info after printk works. This is delayed info dump.
 */
void show_ucode_info_early(void)
{
        struct ucode_cpu_info uci;

        if (delay_ucode_info) {
                collect_cpu_info_early(&uci);
                print_ucode_info(&uci, current_mc_date);
                delay_ucode_info = 0;
        }
}

/*
 * At this point, we can not call printk() yet. Keep microcode patch number in
 * mc_saved_data.mc_saved and delay printing microcode info in
 * show_ucode_info_early() until printk() works.
 */
static void print_ucode(struct ucode_cpu_info *uci)
{
        struct microcode_intel *mc_intel;
        int *delay_ucode_info_p;
        int *current_mc_date_p;

        mc_intel = uci->mc;
        if (mc_intel == NULL)
                return;

        delay_ucode_info_p = (int *)__pa_nodebug(&delay_ucode_info);
        current_mc_date_p = (int *)__pa_nodebug(&current_mc_date);

        *delay_ucode_info_p = 1;
        *current_mc_date_p = mc_intel->hdr.date;
}
#else

/*
 * Flush global tlb. We only do this in x86_64 where paging has been enabled
 * already and PGE should be enabled as well.
 */
static inline void flush_tlb_early(void)
{
        __native_flush_tlb_global_irq_disabled();
}

static inline void print_ucode(struct ucode_cpu_info *uci)
{
        struct microcode_intel *mc_intel;

        mc_intel = uci->mc;
        if (mc_intel == NULL)
                return;

        print_ucode_info(uci, mc_intel->hdr.date);
}
#endif

static int apply_microcode_early(struct mc_saved_data *mc_saved_data,
                                 struct ucode_cpu_info *uci)
{
        struct microcode_intel *mc_intel;
        unsigned int val[2];

        mc_intel = uci->mc;
        if (mc_intel == NULL)
                return 0;

        /* write microcode via MSR 0x79 */
        native_wrmsr(MSR_IA32_UCODE_WRITE,
              (unsigned long) mc_intel->bits,
              (unsigned long) mc_intel->bits >> 16 >> 16);
        native_wrmsr(MSR_IA32_UCODE_REV, 0, 0);

        /* As documented in the SDM: Do a CPUID 1 here */
        sync_core();

        /* get the current revision from MSR 0x8B */
        native_rdmsr(MSR_IA32_UCODE_REV, val[0], val[1]);
        if (val[1] != mc_intel->hdr.rev)
                return -1;

#ifdef CONFIG_X86_64
        /* Flush global tlb. This is precaution. */
        flush_tlb_early();
#endif
        uci->cpu_sig.rev = val[1];

        print_ucode(uci);

        return 0;
}

/*
 * This function converts microcode patch offsets previously stored in
 * mc_saved_in_initrd to pointers and stores the pointers in mc_saved_data.
 */
int __init save_microcode_in_initrd_intel(void)
{
        unsigned int count = mc_saved_data.mc_saved_count;
        struct microcode_intel *mc_saved[MAX_UCODE_COUNT];
        int ret = 0;

        if (count == 0)
                return ret;

        microcode_pointer(mc_saved, mc_saved_in_initrd, initrd_start, count);
        ret = save_microcode(&mc_saved_data, mc_saved, count);
        if (ret)
                pr_err("Cannot save microcode patches from initrd.\n");

        show_saved_mc();

        return ret;
}

static void __init
_load_ucode_intel_bsp(struct mc_saved_data *mc_saved_data,
                      unsigned long *mc_saved_in_initrd,
                      unsigned long initrd_start_early,
                      unsigned long initrd_end_early,
                      struct ucode_cpu_info *uci)
{
        collect_cpu_info_early(uci);
        scan_microcode(initrd_start_early, initrd_end_early, mc_saved_data,
                       mc_saved_in_initrd, uci);
        load_microcode(mc_saved_data, mc_saved_in_initrd,
                       initrd_start_early, uci);
        apply_microcode_early(mc_saved_data, uci);
}

void __init
load_ucode_intel_bsp(void)
{
        u64 ramdisk_image, ramdisk_size;
        unsigned long initrd_start_early, initrd_end_early;
        struct ucode_cpu_info uci;
#ifdef CONFIG_X86_32
        struct boot_params *boot_params_p;

        boot_params_p = (struct boot_params *)__pa_nodebug(&boot_params);
        ramdisk_image = boot_params_p->hdr.ramdisk_image;
        ramdisk_size  = boot_params_p->hdr.ramdisk_size;
        initrd_start_early = ramdisk_image;
        initrd_end_early = initrd_start_early + ramdisk_size;

        _load_ucode_intel_bsp(
                (struct mc_saved_data *)__pa_nodebug(&mc_saved_data),
                (unsigned long *)__pa_nodebug(&mc_saved_in_initrd),
                initrd_start_early, initrd_end_early, &uci);
#else
        ramdisk_image = boot_params.hdr.ramdisk_image;
        ramdisk_size  = boot_params.hdr.ramdisk_size;
        initrd_start_early = ramdisk_image + PAGE_OFFSET;
        initrd_end_early = initrd_start_early + ramdisk_size;

        _load_ucode_intel_bsp(&mc_saved_data, mc_saved_in_initrd,
                              initrd_start_early, initrd_end_early, &uci);
#endif
}

void load_ucode_intel_ap(void)
{
        struct mc_saved_data *mc_saved_data_p;
        struct ucode_cpu_info uci;
        unsigned long *mc_saved_in_initrd_p;
        unsigned long initrd_start_addr;
#ifdef CONFIG_X86_32
        unsigned long *initrd_start_p;

        mc_saved_in_initrd_p =
                (unsigned long *)__pa_nodebug(mc_saved_in_initrd);
        mc_saved_data_p = (struct mc_saved_data *)__pa_nodebug(&mc_saved_data);
        initrd_start_p = (unsigned long *)__pa_nodebug(&initrd_start);
        initrd_start_addr = (unsigned long)__pa_nodebug(*initrd_start_p);
#else
        mc_saved_data_p = &mc_saved_data;
        mc_saved_in_initrd_p = mc_saved_in_initrd;
        initrd_start_addr = initrd_start;
#endif

        /*
         * If there is no valid ucode previously saved in memory, no need to
         * update ucode on this AP.
         */
        if (mc_saved_data_p->mc_saved_count == 0)
                return;

        collect_cpu_info_early(&uci);
        load_microcode(mc_saved_data_p, mc_saved_in_initrd_p,
                       initrd_start_addr, &uci);
        apply_microcode_early(mc_saved_data_p, &uci);
}