cleanup.c

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/*
 * MTRR (Memory Type Range Register) cleanup
 *
 *  Copyright (C) 2009 Yinghai Lu
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the Free
 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
#include <linux/module.h>
#include <linux/init.h>
#include <linux/pci.h>
#include <linux/smp.h>
#include <linux/cpu.h>
#include <linux/mutex.h>
#include <linux/uaccess.h>
#include <linux/kvm_para.h>
#include <linux/range.h>

#include <asm/processor.h>
#include <asm/e820.h>
#include <asm/mtrr.h>
#include <asm/msr.h>

#include "mtrr.h"

struct var_mtrr_range_state {
    unsigned long   base_pfn;
    unsigned long   size_pfn;
    mtrr_type   type;
};

struct var_mtrr_state {
    unsigned long   range_startk;
    unsigned long   range_sizek;
    unsigned long   chunk_sizek;
    unsigned long   gran_sizek;
    unsigned int    reg;
};

/* Should be related to MTRR_VAR_RANGES nums */
#define RANGE_NUM               256

static struct range __initdata      range[RANGE_NUM];
static int __initdata               nr_range;

static struct var_mtrr_range_state __initdata   range_state[RANGE_NUM];

static int __initdata debug_print;
#define Dprintk(x...) do { if (debug_print) printk(KERN_DEBUG x); } while (0)

#define BIOS_BUG_MSG KERN_WARNING \
    "WARNING: BIOS bug: VAR MTRR %d contains strange UC entry under 1M, check with your system vendor!\n"

static int __init
x86_get_mtrr_mem_range(struct range *range, int nr_range,
               unsigned long extra_remove_base,
               unsigned long extra_remove_size)
{
    unsigned long base, size;
    mtrr_type type;
    int i;

    for (i = 0; i < num_var_ranges; i++) {
        type = range_state[i].type;
        if (type != MTRR_TYPE_WRBACK)
            continue;
        base = range_state[i].base_pfn;
        size = range_state[i].size_pfn;
        nr_range = add_range_with_merge(range, RANGE_NUM, nr_range,
                        base, base + size);
    }
    if (debug_print) {
        printk(KERN_DEBUG "After WB checking\n");
        for (i = 0; i < nr_range; i++)
            printk(KERN_DEBUG "MTRR MAP PFN: %016llx - %016llx\n",
                 range[i].start, range[i].end);
    }

    /* Take out UC ranges: */
    for (i = 0; i < num_var_ranges; i++) {
        type = range_state[i].type;
        if (type != MTRR_TYPE_UNCACHABLE &&
            type != MTRR_TYPE_WRPROT)
            continue;
        size = range_state[i].size_pfn;
        if (!size)
            continue;
        base = range_state[i].base_pfn;
        if (base < (1<<(20-PAGE_SHIFT)) && mtrr_state.have_fixed &&
            (mtrr_state.enabled & 1)) {
            /* Var MTRR contains UC entry below 1M? Skip it: */
            printk(BIOS_BUG_MSG, i);
            if (base + size <= (1<<(20-PAGE_SHIFT)))
                continue;
            size -= (1<<(20-PAGE_SHIFT)) - base;
            base = 1<<(20-PAGE_SHIFT);
        }
        subtract_range(range, RANGE_NUM, base, base + size);
    }
    if (extra_remove_size)
        subtract_range(range, RANGE_NUM, extra_remove_base,
                 extra_remove_base + extra_remove_size);

    if  (debug_print) {
        printk(KERN_DEBUG "After UC checking\n");
        for (i = 0; i < RANGE_NUM; i++) {
            if (!range[i].end)
                continue;
            printk(KERN_DEBUG "MTRR MAP PFN: %016llx - %016llx\n",
                 range[i].start, range[i].end);
        }
    }

    /* sort the ranges */
    nr_range = clean_sort_range(range, RANGE_NUM);
    if  (debug_print) {
        printk(KERN_DEBUG "After sorting\n");
        for (i = 0; i < nr_range; i++)
            printk(KERN_DEBUG "MTRR MAP PFN: %016llx - %016llx\n",
                 range[i].start, range[i].end);
    }

    return nr_range;
}

#ifdef CONFIG_MTRR_SANITIZER

static unsigned long __init sum_ranges(struct range *range, int nr_range)
{
    unsigned long sum = 0;
    int i;

    for (i = 0; i < nr_range; i++)
        sum += range[i].end - range[i].start;

    return sum;
}

static int enable_mtrr_cleanup __initdata =
    CONFIG_MTRR_SANITIZER_ENABLE_DEFAULT;

static int __init disable_mtrr_cleanup_setup(char *str)
{
    enable_mtrr_cleanup = 0;
    return 0;
}
early_param("disable_mtrr_cleanup", disable_mtrr_cleanup_setup);

static int __init enable_mtrr_cleanup_setup(char *str)
{
    enable_mtrr_cleanup = 1;
    return 0;
}
early_param("enable_mtrr_cleanup", enable_mtrr_cleanup_setup);

static int __init mtrr_cleanup_debug_setup(char *str)
{
    debug_print = 1;
    return 0;
}
early_param("mtrr_cleanup_debug", mtrr_cleanup_debug_setup);

static void __init
set_var_mtrr(unsigned int reg, unsigned long basek, unsigned long sizek,
         unsigned char type, unsigned int address_bits)
{
    u32 base_lo, base_hi, mask_lo, mask_hi;
    u64 base, mask;

    if (!sizek) {
        fill_mtrr_var_range(reg, 0, 0, 0, 0);
        return;
    }

    mask = (1ULL << address_bits) - 1;
    mask &= ~((((u64)sizek) << 10) - 1);

    base = ((u64)basek) << 10;

    base |= type;
    mask |= 0x800;

    base_lo = base & ((1ULL<<32) - 1);
    base_hi = base >> 32;

    mask_lo = mask & ((1ULL<<32) - 1);
    mask_hi = mask >> 32;

    fill_mtrr_var_range(reg, base_lo, base_hi, mask_lo, mask_hi);
}

static void __init
save_var_mtrr(unsigned int reg, unsigned long basek, unsigned long sizek,
          unsigned char type)
{
    range_state[reg].base_pfn = basek >> (PAGE_SHIFT - 10);
    range_state[reg].size_pfn = sizek >> (PAGE_SHIFT - 10);
    range_state[reg].type = type;
}

static void __init set_var_mtrr_all(unsigned int address_bits)
{
    unsigned long basek, sizek;
    unsigned char type;
    unsigned int reg;

    for (reg = 0; reg < num_var_ranges; reg++) {
        basek = range_state[reg].base_pfn << (PAGE_SHIFT - 10);
        sizek = range_state[reg].size_pfn << (PAGE_SHIFT - 10);
        type = range_state[reg].type;

        set_var_mtrr(reg, basek, sizek, type, address_bits);
    }
}

static unsigned long to_size_factor(unsigned long sizek, char *factorp)
{
    unsigned long base = sizek;
    char factor;

    if (base & ((1<<10) - 1)) {
        /* Not MB-aligned: */
        factor = 'K';
    } else if (base & ((1<<20) - 1)) {
        factor = 'M';
        base >>= 10;
    } else {
        factor = 'G';
        base >>= 20;
    }

    *factorp = factor;

    return base;
}

static unsigned int __init
range_to_mtrr(unsigned int reg, unsigned long range_startk,
          unsigned long range_sizek, unsigned char type)
{
    if (!range_sizek || (reg >= num_var_ranges))
        return reg;

    while (range_sizek) {
        unsigned long max_align, align;
        unsigned long sizek;

        /* Compute the maximum size with which we can make a range: */
        if (range_startk)
            max_align = __ffs(range_startk);
        else
            max_align = BITS_PER_LONG - 1;

        align = __fls(range_sizek);
        if (align > max_align)
            align = max_align;

        sizek = 1UL << align;
        if (debug_print) {
            char start_factor = 'K', size_factor = 'K';
            unsigned long start_base, size_base;

            start_base = to_size_factor(range_startk, &start_factor);
            size_base = to_size_factor(sizek, &size_factor);

            Dprintk("Setting variable MTRR %d, "
                "base: %ld%cB, range: %ld%cB, type %s\n",
                reg, start_base, start_factor,
                size_base, size_factor,
                (type == MTRR_TYPE_UNCACHABLE) ? "UC" :
                   ((type == MTRR_TYPE_WRBACK) ? "WB" : "Other")
                );
        }
        save_var_mtrr(reg++, range_startk, sizek, type);
        range_startk += sizek;
        range_sizek -= sizek;
        if (reg >= num_var_ranges)
            break;
    }
    return reg;
}

static unsigned __init
range_to_mtrr_with_hole(struct var_mtrr_state *state, unsigned long basek,
            unsigned long sizek)
{
    unsigned long hole_basek, hole_sizek;
    unsigned long second_basek, second_sizek;
    unsigned long range0_basek, range0_sizek;
    unsigned long range_basek, range_sizek;
    unsigned long chunk_sizek;
    unsigned long gran_sizek;

    hole_basek = 0;
    hole_sizek = 0;
    second_basek = 0;
    second_sizek = 0;
    chunk_sizek = state->chunk_sizek;
    gran_sizek = state->gran_sizek;

    /* Align with gran size, prevent small block used up MTRRs: */
    range_basek = ALIGN(state->range_startk, gran_sizek);
    if ((range_basek > basek) && basek)
        return second_sizek;

    state->range_sizek -= (range_basek - state->range_startk);
    range_sizek = ALIGN(state->range_sizek, gran_sizek);

    while (range_sizek > state->range_sizek) {
        range_sizek -= gran_sizek;
        if (!range_sizek)
            return 0;
    }
    state->range_sizek = range_sizek;

    /* Try to append some small hole: */
    range0_basek = state->range_startk;
    range0_sizek = ALIGN(state->range_sizek, chunk_sizek);

    /* No increase: */
    if (range0_sizek == state->range_sizek) {
        Dprintk("rangeX: %016lx - %016lx\n",
            range0_basek<<10,
            (range0_basek + state->range_sizek)<<10);
        state->reg = range_to_mtrr(state->reg, range0_basek,
                state->range_sizek, MTRR_TYPE_WRBACK);
        return 0;
    }

    /* Only cut back when it is not the last: */
    if (sizek) {
        while (range0_basek + range0_sizek > (basek + sizek)) {
            if (range0_sizek >= chunk_sizek)
                range0_sizek -= chunk_sizek;
            else
                range0_sizek = 0;

            if (!range0_sizek)
                break;
        }
    }

second_try:
    range_basek = range0_basek + range0_sizek;

    /* One hole in the middle: */
    if (range_basek > basek && range_basek <= (basek + sizek))
        second_sizek = range_basek - basek;

    if (range0_sizek > state->range_sizek) {

        /* One hole in middle or at the end: */
        hole_sizek = range0_sizek - state->range_sizek - second_sizek;

        /* Hole size should be less than half of range0 size: */
        if (hole_sizek >= (range0_sizek >> 1) &&
            range0_sizek >= chunk_sizek) {
            range0_sizek -= chunk_sizek;
            second_sizek = 0;
            hole_sizek = 0;

            goto second_try;
        }
    }

    if (range0_sizek) {
        Dprintk("range0: %016lx - %016lx\n",
            range0_basek<<10,
            (range0_basek + range0_sizek)<<10);
        state->reg = range_to_mtrr(state->reg, range0_basek,
                range0_sizek, MTRR_TYPE_WRBACK);
    }

    if (range0_sizek < state->range_sizek) {
        /* Need to handle left over range: */
        range_sizek = state->range_sizek - range0_sizek;

        Dprintk("range: %016lx - %016lx\n",
             range_basek<<10,
             (range_basek + range_sizek)<<10);

        state->reg = range_to_mtrr(state->reg, range_basek,
                 range_sizek, MTRR_TYPE_WRBACK);
    }

    if (hole_sizek) {
        hole_basek = range_basek - hole_sizek - second_sizek;
        Dprintk("hole: %016lx - %016lx\n",
             hole_basek<<10,
             (hole_basek + hole_sizek)<<10);
        state->reg = range_to_mtrr(state->reg, hole_basek,
                 hole_sizek, MTRR_TYPE_UNCACHABLE);
    }

    return second_sizek;
}

static void __init
set_var_mtrr_range(struct var_mtrr_state *state, unsigned long base_pfn,
           unsigned long size_pfn)
{
    unsigned long basek, sizek;
    unsigned long second_sizek = 0;

    if (state->reg >= num_var_ranges)
        return;

    basek = base_pfn << (PAGE_SHIFT - 10);
    sizek = size_pfn << (PAGE_SHIFT - 10);

    /* See if I can merge with the last range: */
    if ((basek <= 1024) ||
        (state->range_startk + state->range_sizek == basek)) {
        unsigned long endk = basek + sizek;
        state->range_sizek = endk - state->range_startk;
        return;
    }
    /* Write the range mtrrs: */
    if (state->range_sizek != 0)
        second_sizek = range_to_mtrr_with_hole(state, basek, sizek);

    /* Allocate an msr: */
    state->range_startk = basek + second_sizek;
    state->range_sizek  = sizek - second_sizek;
}

/* Mininum size of mtrr block that can take hole: */
static u64 mtrr_chunk_size __initdata = (256ULL<<20);

static int __init parse_mtrr_chunk_size_opt(char *p)
{
    if (!p)
        return -EINVAL;
    mtrr_chunk_size = memparse(p, &p);
    return 0;
}
early_param("mtrr_chunk_size", parse_mtrr_chunk_size_opt);

/* Granularity of mtrr of block: */
static u64 mtrr_gran_size __initdata;

static int __init parse_mtrr_gran_size_opt(char *p)
{
    if (!p)
        return -EINVAL;
    mtrr_gran_size = memparse(p, &p);
    return 0;
}
early_param("mtrr_gran_size", parse_mtrr_gran_size_opt);

static unsigned long nr_mtrr_spare_reg __initdata =
                 CONFIG_MTRR_SANITIZER_SPARE_REG_NR_DEFAULT;

static int __init parse_mtrr_spare_reg(char *arg)
{
    if (arg)
        nr_mtrr_spare_reg = simple_strtoul(arg, NULL, 0);
    return 0;
}
early_param("mtrr_spare_reg_nr", parse_mtrr_spare_reg);

static int __init
x86_setup_var_mtrrs(struct range *range, int nr_range,
            u64 chunk_size, u64 gran_size)
{
    struct var_mtrr_state var_state;
    int num_reg;
    int i;

    var_state.range_startk  = 0;
    var_state.range_sizek   = 0;
    var_state.reg       = 0;
    var_state.chunk_sizek   = chunk_size >> 10;
    var_state.gran_sizek    = gran_size >> 10;

    memset(range_state, 0, sizeof(range_state));

    /* Write the range: */
    for (i = 0; i < nr_range; i++) {
        set_var_mtrr_range(&var_state, range[i].start,
                   range[i].end - range[i].start);
    }

    /* Write the last range: */
    if (var_state.range_sizek != 0)
        range_to_mtrr_with_hole(&var_state, 0, 0);

    num_reg = var_state.reg;
    /* Clear out the extra MTRR's: */
    while (var_state.reg < num_var_ranges) {
        save_var_mtrr(var_state.reg, 0, 0, 0);
        var_state.reg++;
    }

    return num_reg;
}

struct mtrr_cleanup_result {
    unsigned long   gran_sizek;
    unsigned long   chunk_sizek;
    unsigned long   lose_cover_sizek;
    unsigned int    num_reg;
    int     bad;
};

/*
 * gran_size: 64K, 128K, 256K, 512K, 1M, 2M, ..., 2G
 * chunk size: gran_size, ..., 2G
 * so we need (1+16)*8
 */
#define NUM_RESULT  136
#define PSHIFT      (PAGE_SHIFT - 10)

static struct mtrr_cleanup_result __initdata result[NUM_RESULT];
static unsigned long __initdata min_loss_pfn[RANGE_NUM];

static void __init print_out_mtrr_range_state(void)
{
    char start_factor = 'K', size_factor = 'K';
    unsigned long start_base, size_base;
    mtrr_type type;
    int i;

    for (i = 0; i < num_var_ranges; i++) {

        size_base = range_state[i].size_pfn << (PAGE_SHIFT - 10);
        if (!size_base)
            continue;

        size_base = to_size_factor(size_base, &size_factor),
        start_base = range_state[i].base_pfn << (PAGE_SHIFT - 10);
        start_base = to_size_factor(start_base, &start_factor),
        type = range_state[i].type;

        printk(KERN_DEBUG "reg %d, base: %ld%cB, range: %ld%cB, type %s\n",
            i, start_base, start_factor,
            size_base, size_factor,
            (type == MTRR_TYPE_UNCACHABLE) ? "UC" :
                ((type == MTRR_TYPE_WRPROT) ? "WP" :
                 ((type == MTRR_TYPE_WRBACK) ? "WB" : "Other"))
            );
    }
}

static int __init mtrr_need_cleanup(void)
{
    int i;
    mtrr_type type;
    unsigned long size;
    /* Extra one for all 0: */
    int num[MTRR_NUM_TYPES + 1];

    /* Check entries number: */
    memset(num, 0, sizeof(num));
    for (i = 0; i < num_var_ranges; i++) {
        type = range_state[i].type;
        size = range_state[i].size_pfn;
        if (type >= MTRR_NUM_TYPES)
            continue;
        if (!size)
            type = MTRR_NUM_TYPES;
        num[type]++;
    }

    /* Check if we got UC entries: */
    if (!num[MTRR_TYPE_UNCACHABLE])
        return 0;

    /* Check if we only had WB and UC */
    if (num[MTRR_TYPE_WRBACK] + num[MTRR_TYPE_UNCACHABLE] !=
        num_var_ranges - num[MTRR_NUM_TYPES])
        return 0;

    return 1;
}

static unsigned long __initdata range_sums;

static void __init
mtrr_calc_range_state(u64 chunk_size, u64 gran_size,
              unsigned long x_remove_base,
              unsigned long x_remove_size, int i)
{
    static struct range range_new[RANGE_NUM];
    unsigned long range_sums_new;
    static int nr_range_new;
    int num_reg;

    /* Convert ranges to var ranges state: */
    num_reg = x86_setup_var_mtrrs(range, nr_range, chunk_size, gran_size);

    /* We got new setting in range_state, check it: */
    memset(range_new, 0, sizeof(range_new));
    nr_range_new = x86_get_mtrr_mem_range(range_new, 0,
                x_remove_base, x_remove_size);
    range_sums_new = sum_ranges(range_new, nr_range_new);

    result[i].chunk_sizek = chunk_size >> 10;
    result[i].gran_sizek = gran_size >> 10;
    result[i].num_reg = num_reg;

    if (range_sums < range_sums_new) {
        result[i].lose_cover_sizek = (range_sums_new - range_sums) << PSHIFT;
        result[i].bad = 1;
    } else {
        result[i].lose_cover_sizek = (range_sums - range_sums_new) << PSHIFT;
    }

    /* Double check it: */
    if (!result[i].bad && !result[i].lose_cover_sizek) {
        if (nr_range_new != nr_range || memcmp(range, range_new, sizeof(range)))
            result[i].bad = 1;
    }

    if (!result[i].bad && (range_sums - range_sums_new < min_loss_pfn[num_reg]))
        min_loss_pfn[num_reg] = range_sums - range_sums_new;
}

static void __init mtrr_print_out_one_result(int i)
{
    unsigned long gran_base, chunk_base, lose_base;
    char gran_factor, chunk_factor, lose_factor;

    gran_base = to_size_factor(result[i].gran_sizek, &gran_factor);
    chunk_base = to_size_factor(result[i].chunk_sizek, &chunk_factor);
    lose_base = to_size_factor(result[i].lose_cover_sizek, &lose_factor);

    pr_info("%sgran_size: %ld%c \tchunk_size: %ld%c \t",
        result[i].bad ? "*BAD*" : " ",
        gran_base, gran_factor, chunk_base, chunk_factor);
    pr_cont("num_reg: %d  \tlose cover RAM: %s%ld%c\n",
        result[i].num_reg, result[i].bad ? "-" : "",
        lose_base, lose_factor);
}

static int __init mtrr_search_optimal_index(void)
{
    int num_reg_good;
    int index_good;
    int i;

    if (nr_mtrr_spare_reg >= num_var_ranges)
        nr_mtrr_spare_reg = num_var_ranges - 1;

    num_reg_good = -1;
    for (i = num_var_ranges - nr_mtrr_spare_reg; i > 0; i--) {
        if (!min_loss_pfn[i])
            num_reg_good = i;
    }

    index_good = -1;
    if (num_reg_good != -1) {
        for (i = 0; i < NUM_RESULT; i++) {
            if (!result[i].bad &&
                result[i].num_reg == num_reg_good &&
                !result[i].lose_cover_sizek) {
                index_good = i;
                break;
            }
        }
    }

    return index_good;
}

int __init mtrr_cleanup(unsigned address_bits)
{
    unsigned long x_remove_base, x_remove_size;
    unsigned long base, size, def, dummy;
    u64 chunk_size, gran_size;
    mtrr_type type;
    int index_good;
    int i;

    if (!is_cpu(INTEL) || enable_mtrr_cleanup < 1)
        return 0;

    rdmsr(MSR_MTRRdefType, def, dummy);
    def &= 0xff;
    if (def != MTRR_TYPE_UNCACHABLE)
        return 0;

    /* Get it and store it aside: */
    memset(range_state, 0, sizeof(range_state));
    for (i = 0; i < num_var_ranges; i++) {
        mtrr_if->get(i, &base, &size, &type);
        range_state[i].base_pfn = base;
        range_state[i].size_pfn = size;
        range_state[i].type = type;
    }

    /* Check if we need handle it and can handle it: */
    if (!mtrr_need_cleanup())
        return 0;

    /* Print original var MTRRs at first, for debugging: */
    printk(KERN_DEBUG "original variable MTRRs\n");
    print_out_mtrr_range_state();

    memset(range, 0, sizeof(range));
    x_remove_size = 0;
    x_remove_base = 1 << (32 - PAGE_SHIFT);
    if (mtrr_tom2)
        x_remove_size = (mtrr_tom2 >> PAGE_SHIFT) - x_remove_base;

    nr_range = x86_get_mtrr_mem_range(range, 0, x_remove_base, x_remove_size);
    /*
     * [0, 1M) should always be covered by var mtrr with WB
     * and fixed mtrrs should take effect before var mtrr for it:
     */
    nr_range = add_range_with_merge(range, RANGE_NUM, nr_range, 0,
                    1ULL<<(20 - PAGE_SHIFT));
    /* Sort the ranges: */
    sort_range(range, nr_range);

    range_sums = sum_ranges(range, nr_range);
    printk(KERN_INFO "total RAM covered: %ldM\n",
           range_sums >> (20 - PAGE_SHIFT));

    if (mtrr_chunk_size && mtrr_gran_size) {
        i = 0;
        mtrr_calc_range_state(mtrr_chunk_size, mtrr_gran_size,
                      x_remove_base, x_remove_size, i);

        mtrr_print_out_one_result(i);

        if (!result[i].bad) {
            set_var_mtrr_all(address_bits);
            printk(KERN_DEBUG "New variable MTRRs\n");
            print_out_mtrr_range_state();
            return 1;
        }
        printk(KERN_INFO "invalid mtrr_gran_size or mtrr_chunk_size, "
               "will find optimal one\n");
    }

    i = 0;
    memset(min_loss_pfn, 0xff, sizeof(min_loss_pfn));
    memset(result, 0, sizeof(result));
    for (gran_size = (1ULL<<16); gran_size < (1ULL<<32); gran_size <<= 1) {

        for (chunk_size = gran_size; chunk_size < (1ULL<<32);
             chunk_size <<= 1) {

            if (i >= NUM_RESULT)
                continue;

            mtrr_calc_range_state(chunk_size, gran_size,
                      x_remove_base, x_remove_size, i);
            if (debug_print) {
                mtrr_print_out_one_result(i);
                printk(KERN_INFO "\n");
            }

            i++;
        }
    }

    /* Try to find the optimal index: */
    index_good = mtrr_search_optimal_index();

    if (index_good != -1) {
        printk(KERN_INFO "Found optimal setting for mtrr clean up\n");
        i = index_good;
        mtrr_print_out_one_result(i);

        /* Convert ranges to var ranges state: */
        chunk_size = result[i].chunk_sizek;
        chunk_size <<= 10;
        gran_size = result[i].gran_sizek;
        gran_size <<= 10;
        x86_setup_var_mtrrs(range, nr_range, chunk_size, gran_size);
        set_var_mtrr_all(address_bits);
        printk(KERN_DEBUG "New variable MTRRs\n");
        print_out_mtrr_range_state();
        return 1;
    } else {
        /* print out all */
        for (i = 0; i < NUM_RESULT; i++)
            mtrr_print_out_one_result(i);
    }

    printk(KERN_INFO "mtrr_cleanup: can not find optimal value\n");
    printk(KERN_INFO "please specify mtrr_gran_size/mtrr_chunk_size\n");

    return 0;
}
#else
int __init mtrr_cleanup(unsigned address_bits)
{
    return 0;
}
#endif

static int disable_mtrr_trim;

static int __init disable_mtrr_trim_setup(char *str)
{
    disable_mtrr_trim = 1;
    return 0;
}
early_param("disable_mtrr_trim", disable_mtrr_trim_setup);

/*
 * Newer AMD K8s and later CPUs have a special magic MSR way to force WB
 * for memory >4GB. Check for that here.
 * Note this won't check if the MTRRs < 4GB where the magic bit doesn't
 * apply to are wrong, but so far we don't know of any such case in the wild.
 */
#define Tom2Enabled     (1U << 21)
#define Tom2ForceMemTypeWB  (1U << 22)

int __init amd_special_default_mtrr(void)
{
    u32 l, h;

    if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD)
        return 0;
    if (boot_cpu_data.x86 < 0xf)
        return 0;
    /* In case some hypervisor doesn't pass SYSCFG through: */
    if (rdmsr_safe(MSR_K8_SYSCFG, &l, &h) < 0)
        return 0;
    /*
     * Memory between 4GB and top of mem is forced WB by this magic bit.
     * Reserved before K8RevF, but should be zero there.
     */
    if ((l & (Tom2Enabled | Tom2ForceMemTypeWB)) ==
         (Tom2Enabled | Tom2ForceMemTypeWB))
        return 1;
    return 0;
}

static u64 __init
real_trim_memory(unsigned long start_pfn, unsigned long limit_pfn)
{
    u64 trim_start, trim_size;

    trim_start = start_pfn;
    trim_start <<= PAGE_SHIFT;

    trim_size = limit_pfn;
    trim_size <<= PAGE_SHIFT;
    trim_size -= trim_start;

    return e820_update_range(trim_start, trim_size, E820_RAM, E820_RESERVED);
}

int __init mtrr_trim_uncached_memory(unsigned long end_pfn)
{
    unsigned long i, base, size, highest_pfn = 0, def, dummy;
    mtrr_type type;
    u64 total_trim_size;
    /* extra one for all 0 */
    int num[MTRR_NUM_TYPES + 1];

    /*
     * Make sure we only trim uncachable memory on machines that
     * support the Intel MTRR architecture:
     */
    if (!is_cpu(INTEL) || disable_mtrr_trim)
        return 0;

    rdmsr(MSR_MTRRdefType, def, dummy);
    def &= 0xff;
    if (def != MTRR_TYPE_UNCACHABLE)
        return 0;

    /* Get it and store it aside: */
    memset(range_state, 0, sizeof(range_state));
    for (i = 0; i < num_var_ranges; i++) {
        mtrr_if->get(i, &base, &size, &type);
        range_state[i].base_pfn = base;
        range_state[i].size_pfn = size;
        range_state[i].type = type;
    }

    /* Find highest cached pfn: */
    for (i = 0; i < num_var_ranges; i++) {
        type = range_state[i].type;
        if (type != MTRR_TYPE_WRBACK)
            continue;
        base = range_state[i].base_pfn;
        size = range_state[i].size_pfn;
        if (highest_pfn < base + size)
            highest_pfn = base + size;
    }

    /* kvm/qemu doesn't have mtrr set right, don't trim them all: */
    if (!highest_pfn) {
        printk(KERN_INFO "CPU MTRRs all blank - virtualized system.\n");
        return 0;
    }

    /* Check entries number: */
    memset(num, 0, sizeof(num));
    for (i = 0; i < num_var_ranges; i++) {
        type = range_state[i].type;
        if (type >= MTRR_NUM_TYPES)
            continue;
        size = range_state[i].size_pfn;
        if (!size)
            type = MTRR_NUM_TYPES;
        num[type]++;
    }

    /* No entry for WB? */
    if (!num[MTRR_TYPE_WRBACK])
        return 0;

    /* Check if we only had WB and UC: */
    if (num[MTRR_TYPE_WRBACK] + num[MTRR_TYPE_UNCACHABLE] !=
        num_var_ranges - num[MTRR_NUM_TYPES])
        return 0;

    memset(range, 0, sizeof(range));
    nr_range = 0;
    if (mtrr_tom2) {
        range[nr_range].start = (1ULL<<(32 - PAGE_SHIFT));
        range[nr_range].end = mtrr_tom2 >> PAGE_SHIFT;
        if (highest_pfn < range[nr_range].end)
            highest_pfn = range[nr_range].end;
        nr_range++;
    }
    nr_range = x86_get_mtrr_mem_range(range, nr_range, 0, 0);

    /* Check the head: */
    total_trim_size = 0;
    if (range[0].start)
        total_trim_size += real_trim_memory(0, range[0].start);

    /* Check the holes: */
    for (i = 0; i < nr_range - 1; i++) {
        if (range[i].end < range[i+1].start)
            total_trim_size += real_trim_memory(range[i].end,
                                range[i+1].start);
    }

    /* Check the top: */
    i = nr_range - 1;
    if (range[i].end < end_pfn)
        total_trim_size += real_trim_memory(range[i].end,
                             end_pfn);

    if (total_trim_size) {
        pr_warning("WARNING: BIOS bug: CPU MTRRs don't cover all of memory, losing %lluMB of RAM.\n", total_trim_size >> 20);

        if (!changed_by_mtrr_cleanup)
            WARN_ON(1);

        pr_info("update e820 for mtrr\n");
        update_e820();

        return 1;
    }

    return 0;
}