/*
 * 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/sort.h>
#include <linux/mutex.h>
#include <linux/uaccess.h>
#include <linux/kvm_para.h>

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

#include "mtrr.h"

struct res_range {
        unsigned long   start;
        unsigned long   end;
};

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 res_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)


static int __init
add_range(struct res_range *range, int nr_range,
          unsigned long start, unsigned long end)
{
        /* Out of slots: */
        if (nr_range >= RANGE_NUM)
                return nr_range;

        range[nr_range].start = start;
        range[nr_range].end = end;

        nr_range++;

        return nr_range;
}

static int __init
add_range_with_merge(struct res_range *range, int nr_range,
                     unsigned long start, unsigned long end)
{
        int i;

        /* Try to merge it with old one: */
        for (i = 0; i < nr_range; i++) {
                unsigned long final_start, final_end;
                unsigned long common_start, common_end;

                if (!range[i].end)
                        continue;

                common_start = max(range[i].start, start);
                common_end = min(range[i].end, end);
                if (common_start > common_end + 1)
                        continue;

                final_start = min(range[i].start, start);
                final_end = max(range[i].end, end);

                range[i].start = final_start;
                range[i].end =  final_end;
                return nr_range;
        }

        /* Need to add it: */
        return add_range(range, nr_range, start, end);
}

static void __init
subtract_range(struct res_range *range, unsigned long start, unsigned long end)
{
        int i, j;

        for (j = 0; j < RANGE_NUM; j++) {
                if (!range[j].end)
                        continue;

                if (start <= range[j].start && end >= range[j].end) {
                        range[j].start = 0;
                        range[j].end = 0;
                        continue;
                }

                if (start <= range[j].start && end < range[j].end &&
                    range[j].start < end + 1) {
                        range[j].start = end + 1;
                        continue;
                }


                if (start > range[j].start && end >= range[j].end &&
                    range[j].end > start - 1) {
                        range[j].end = start - 1;
                        continue;
                }

                if (start > range[j].start && end < range[j].end) {
                        /* Find the new spare: */
                        for (i = 0; i < RANGE_NUM; i++) {
                                if (range[i].end == 0)
                                        break;
                        }
                        if (i < RANGE_NUM) {
                                range[i].end = range[j].end;
                                range[i].start = end + 1;
                        } else {
                                printk(KERN_ERR "run of slot in ranges\n");
                        }
                        range[j].end = start - 1;
                        continue;
                }
        }
}

static int __init cmp_range(const void *x1, const void *x2)
{
        const struct res_range *r1 = x1;
        const struct res_range *r2 = x2;
        long start1, start2;

        start1 = r1->start;
        start2 = r2->start;

        return start1 - start2;
}

#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 res_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, nr_range, base,
                                                base + size - 1);
        }
        if (debug_print) {
                printk(KERN_DEBUG "After WB checking\n");
                for (i = 0; i < nr_range; i++)
                        printk(KERN_DEBUG "MTRR MAP PFN: %016lx - %016lx\n",
                                 range[i].start, range[i].end + 1);
        }

        /* 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, base, base + size - 1);
        }
        if (extra_remove_size)
                subtract_range(range, extra_remove_base,
                                 extra_remove_base + extra_remove_size  - 1);

        /* get new range num */
        nr_range = 0;
        for (i = 0; i < RANGE_NUM; i++) {
                if (!range[i].end)
                        continue;
                nr_range++;
        }
        if  (debug_print) {
                printk(KERN_DEBUG "After UC checking\n");
                for (i = 0; i < nr_range; i++)
                        printk(KERN_DEBUG "MTRR MAP PFN: %016lx - %016lx\n",
                                 range[i].start, range[i].end + 1);
        }

        /* sort the ranges */
        sort(range, nr_range, sizeof(struct res_range), cmp_range, NULL);
        if  (debug_print) {
                printk(KERN_DEBUG "After sorting\n");
                for (i = 0; i < nr_range; i++)
                        printk(KERN_DEBUG "MTRR MAP PFN: %016lx - %016lx\n",
                                 range[i].start, range[i].end + 1);
        }

        /* clear those is not used */
        for (i = nr_range; i < RANGE_NUM; i++)
                memset(&range[i], 0, sizeof(range[i]));

        return nr_range;
}

#ifdef CONFIG_MTRR_SANITIZER

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

        for (i = 0; i < nr_range; i++)
                sum += range[i].end + 1 - 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) - 1;
                else
                        max_align = 32;

                align = fls(range_sizek) - 1;
                if (align > max_align)
                        align = max_align;

                sizek = 1 << 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 res_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 + 1);
        }

        /* 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;
                if (type == MTRR_TYPE_WRPROT)
                        type = MTRR_TYPE_UNCACHABLE;
                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 res_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, nr_range, 0,
                                        (1ULL<<(20 - PAGE_SHIFT)) - 1);
        /* Sort the ranges: */
        sort(range, nr_range, sizeof(struct res_range), cmp_range, NULL);

        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 || boot_cpu_data.x86 > 0x11)
                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);
}

/**
 * mtrr_trim_uncached_memory - trim RAM not covered by MTRRs
 * @end_pfn: ending page frame number
 *
 * Some buggy BIOSes don't setup the MTRRs properly for systems with certain
 * memory configurations.  This routine checks that the highest MTRR matches
 * the end of memory, to make sure the MTRRs having a write back type cover
 * all of the memory the kernel is intending to use.  If not, it'll trim any
 * memory off the end by adjusting end_pfn, removing it from the kernel's
 * allocation pools, warning the user with an obnoxious message.
 */
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) - 1;
                if (highest_pfn < range[nr_range].end + 1)
                        highest_pfn = range[nr_range].end + 1;
                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 + 1 < range[i+1].start)
                        total_trim_size += real_trim_memory(range[i].end + 1,
                                                            range[i+1].start);
        }

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