x86: fix trimming e820 with MTRR holes. - fix

[safe/jmp/linux-2.6] / arch / x86 / kernel / cpu / mtrr / main.c

/*  Generic MTRR (Memory Type Range Register) driver.

    Copyright (C) 1997-2000  Richard Gooch
    Copyright (c) 2002       Patrick Mochel

    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.

    Richard Gooch may be reached by email at  rgooch@atnf.csiro.au
    The postal address is:
      Richard Gooch, c/o ATNF, P. O. Box 76, Epping, N.S.W., 2121, Australia.

    Source: "Pentium Pro Family Developer's Manual, Volume 3:
    Operating System Writer's Guide" (Intel document number 242692),
    section 11.11.7

    This was cleaned and made readable by Patrick Mochel <mochel@osdl.org> 
    on 6-7 March 2002. 
    Source: Intel Architecture Software Developers Manual, Volume 3: 
    System Programming Guide; Section 9.11. (1997 edition - PPro).
*/

#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/sort.h>

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

u32 num_var_ranges = 0;

unsigned int mtrr_usage_table[MAX_VAR_RANGES];
static DEFINE_MUTEX(mtrr_mutex);

u64 size_or_mask, size_and_mask;

static struct mtrr_ops * mtrr_ops[X86_VENDOR_NUM] = {};

struct mtrr_ops * mtrr_if = NULL;

static void set_mtrr(unsigned int reg, unsigned long base,
                     unsigned long size, mtrr_type type);

void set_mtrr_ops(struct mtrr_ops * ops)
{
        if (ops->vendor && ops->vendor < X86_VENDOR_NUM)
                mtrr_ops[ops->vendor] = ops;
}

/*  Returns non-zero if we have the write-combining memory type  */
static int have_wrcomb(void)
{
        struct pci_dev *dev;
        u8 rev;
        
        if ((dev = pci_get_class(PCI_CLASS_BRIDGE_HOST << 8, NULL)) != NULL) {
                /* ServerWorks LE chipsets < rev 6 have problems with write-combining
                   Don't allow it and leave room for other chipsets to be tagged */
                if (dev->vendor == PCI_VENDOR_ID_SERVERWORKS &&
                    dev->device == PCI_DEVICE_ID_SERVERWORKS_LE) {
                        pci_read_config_byte(dev, PCI_CLASS_REVISION, &rev);
                        if (rev <= 5) {
                                printk(KERN_INFO "mtrr: Serverworks LE rev < 6 detected. Write-combining disabled.\n");
                                pci_dev_put(dev);
                                return 0;
                        }
                }
                /* Intel 450NX errata # 23. Non ascending cacheline evictions to
                   write combining memory may resulting in data corruption */
                if (dev->vendor == PCI_VENDOR_ID_INTEL &&
                    dev->device == PCI_DEVICE_ID_INTEL_82451NX) {
                        printk(KERN_INFO "mtrr: Intel 450NX MMC detected. Write-combining disabled.\n");
                        pci_dev_put(dev);
                        return 0;
                }
                pci_dev_put(dev);
        }               
        return (mtrr_if->have_wrcomb ? mtrr_if->have_wrcomb() : 0);
}

/*  This function returns the number of variable MTRRs  */
static void __init set_num_var_ranges(void)
{
        unsigned long config = 0, dummy;

        if (use_intel()) {
                rdmsr(MTRRcap_MSR, config, dummy);
        } else if (is_cpu(AMD))
                config = 2;
        else if (is_cpu(CYRIX) || is_cpu(CENTAUR))
                config = 8;
        num_var_ranges = config & 0xff;
}

static void __init init_table(void)
{
        int i, max;

        max = num_var_ranges;
        for (i = 0; i < max; i++)
                mtrr_usage_table[i] = 1;
}

struct set_mtrr_data {
        atomic_t        count;
        atomic_t        gate;
        unsigned long   smp_base;
        unsigned long   smp_size;
        unsigned int    smp_reg;
        mtrr_type       smp_type;
};

static void ipi_handler(void *info)
/*  [SUMMARY] Synchronisation handler. Executed by "other" CPUs.
    [RETURNS] Nothing.
*/
{
#ifdef CONFIG_SMP
        struct set_mtrr_data *data = info;
        unsigned long flags;

        local_irq_save(flags);

        atomic_dec(&data->count);
        while(!atomic_read(&data->gate))
                cpu_relax();

        /*  The master has cleared me to execute  */
        if (data->smp_reg != ~0U) 
                mtrr_if->set(data->smp_reg, data->smp_base, 
                             data->smp_size, data->smp_type);
        else
                mtrr_if->set_all();

        atomic_dec(&data->count);
        while(atomic_read(&data->gate))
                cpu_relax();

        atomic_dec(&data->count);
        local_irq_restore(flags);
#endif
}

static inline int types_compatible(mtrr_type type1, mtrr_type type2) {
        return type1 == MTRR_TYPE_UNCACHABLE ||
               type2 == MTRR_TYPE_UNCACHABLE ||
               (type1 == MTRR_TYPE_WRTHROUGH && type2 == MTRR_TYPE_WRBACK) ||
               (type1 == MTRR_TYPE_WRBACK && type2 == MTRR_TYPE_WRTHROUGH);
}

/**
 * set_mtrr - update mtrrs on all processors
 * @reg:        mtrr in question
 * @base:       mtrr base
 * @size:       mtrr size
 * @type:       mtrr type
 *
 * This is kinda tricky, but fortunately, Intel spelled it out for us cleanly:
 * 
 * 1. Send IPI to do the following:
 * 2. Disable Interrupts
 * 3. Wait for all procs to do so 
 * 4. Enter no-fill cache mode
 * 5. Flush caches
 * 6. Clear PGE bit
 * 7. Flush all TLBs
 * 8. Disable all range registers
 * 9. Update the MTRRs
 * 10. Enable all range registers
 * 11. Flush all TLBs and caches again
 * 12. Enter normal cache mode and reenable caching
 * 13. Set PGE 
 * 14. Wait for buddies to catch up
 * 15. Enable interrupts.
 * 
 * What does that mean for us? Well, first we set data.count to the number
 * of CPUs. As each CPU disables interrupts, it'll decrement it once. We wait
 * until it hits 0 and proceed. We set the data.gate flag and reset data.count.
 * Meanwhile, they are waiting for that flag to be set. Once it's set, each 
 * CPU goes through the transition of updating MTRRs. The CPU vendors may each do it 
 * differently, so we call mtrr_if->set() callback and let them take care of it.
 * When they're done, they again decrement data->count and wait for data.gate to 
 * be reset. 
 * When we finish, we wait for data.count to hit 0 and toggle the data.gate flag.
 * Everyone then enables interrupts and we all continue on.
 *
 * Note that the mechanism is the same for UP systems, too; all the SMP stuff
 * becomes nops.
 */
static void set_mtrr(unsigned int reg, unsigned long base,
                     unsigned long size, mtrr_type type)
{
        struct set_mtrr_data data;
        unsigned long flags;

        data.smp_reg = reg;
        data.smp_base = base;
        data.smp_size = size;
        data.smp_type = type;
        atomic_set(&data.count, num_booting_cpus() - 1);
        /* make sure data.count is visible before unleashing other CPUs */
        smp_wmb();
        atomic_set(&data.gate,0);

        /*  Start the ball rolling on other CPUs  */
        if (smp_call_function(ipi_handler, &data, 1, 0) != 0)
                panic("mtrr: timed out waiting for other CPUs\n");

        local_irq_save(flags);

        while(atomic_read(&data.count))
                cpu_relax();

        /* ok, reset count and toggle gate */
        atomic_set(&data.count, num_booting_cpus() - 1);
        smp_wmb();
        atomic_set(&data.gate,1);

        /* do our MTRR business */

        /* HACK!
         * We use this same function to initialize the mtrrs on boot.
         * The state of the boot cpu's mtrrs has been saved, and we want
         * to replicate across all the APs. 
         * If we're doing that @reg is set to something special...
         */
        if (reg != ~0U) 
                mtrr_if->set(reg,base,size,type);

        /* wait for the others */
        while(atomic_read(&data.count))
                cpu_relax();

        atomic_set(&data.count, num_booting_cpus() - 1);
        smp_wmb();
        atomic_set(&data.gate,0);

        /*
         * Wait here for everyone to have seen the gate change
         * So we're the last ones to touch 'data'
         */
        while(atomic_read(&data.count))
                cpu_relax();

        local_irq_restore(flags);
}

/**
 *      mtrr_add_page - Add a memory type region
 *      @base: Physical base address of region in pages (in units of 4 kB!)
 *      @size: Physical size of region in pages (4 kB)
 *      @type: Type of MTRR desired
 *      @increment: If this is true do usage counting on the region
 *
 *      Memory type region registers control the caching on newer Intel and
 *      non Intel processors. This function allows drivers to request an
 *      MTRR is added. The details and hardware specifics of each processor's
 *      implementation are hidden from the caller, but nevertheless the 
 *      caller should expect to need to provide a power of two size on an
 *      equivalent power of two boundary.
 *
 *      If the region cannot be added either because all regions are in use
 *      or the CPU cannot support it a negative value is returned. On success
 *      the register number for this entry is returned, but should be treated
 *      as a cookie only.
 *
 *      On a multiprocessor machine the changes are made to all processors.
 *      This is required on x86 by the Intel processors.
 *
 *      The available types are
 *
 *      %MTRR_TYPE_UNCACHABLE   -       No caching
 *
 *      %MTRR_TYPE_WRBACK       -       Write data back in bursts whenever
 *
 *      %MTRR_TYPE_WRCOMB       -       Write data back soon but allow bursts
 *
 *      %MTRR_TYPE_WRTHROUGH    -       Cache reads but not writes
 *
 *      BUGS: Needs a quiet flag for the cases where drivers do not mind
 *      failures and do not wish system log messages to be sent.
 */

int mtrr_add_page(unsigned long base, unsigned long size, 
                  unsigned int type, bool increment)
{
        int i, replace, error;
        mtrr_type ltype;
        unsigned long lbase, lsize;

        if (!mtrr_if)
                return -ENXIO;
                
        if ((error = mtrr_if->validate_add_page(base,size,type)))
                return error;

        if (type >= MTRR_NUM_TYPES) {
                printk(KERN_WARNING "mtrr: type: %u invalid\n", type);
                return -EINVAL;
        }

        /*  If the type is WC, check that this processor supports it  */
        if ((type == MTRR_TYPE_WRCOMB) && !have_wrcomb()) {
                printk(KERN_WARNING
                       "mtrr: your processor doesn't support write-combining\n");
                return -ENOSYS;
        }

        if (!size) {
                printk(KERN_WARNING "mtrr: zero sized request\n");
                return -EINVAL;
        }

        if (base & size_or_mask || size & size_or_mask) {
                printk(KERN_WARNING "mtrr: base or size exceeds the MTRR width\n");
                return -EINVAL;
        }

        error = -EINVAL;
        replace = -1;

        /* No CPU hotplug when we change MTRR entries */
        get_online_cpus();
        /*  Search for existing MTRR  */
        mutex_lock(&mtrr_mutex);
        for (i = 0; i < num_var_ranges; ++i) {
                mtrr_if->get(i, &lbase, &lsize, &ltype);
                if (!lsize || base > lbase + lsize - 1 || base + size - 1 < lbase)
                        continue;
                /*  At this point we know there is some kind of overlap/enclosure  */
                if (base < lbase || base + size - 1 > lbase + lsize - 1) {
                        if (base <= lbase && base + size - 1 >= lbase + lsize - 1) {
                                /*  New region encloses an existing region  */
                                if (type == ltype) {
                                        replace = replace == -1 ? i : -2;
                                        continue;
                                }
                                else if (types_compatible(type, ltype))
                                        continue;
                        }
                        printk(KERN_WARNING
                               "mtrr: 0x%lx000,0x%lx000 overlaps existing"
                               " 0x%lx000,0x%lx000\n", base, size, lbase,
                               lsize);
                        goto out;
                }
                /*  New region is enclosed by an existing region  */
                if (ltype != type) {
                        if (types_compatible(type, ltype))
                                continue;
                        printk (KERN_WARNING "mtrr: type mismatch for %lx000,%lx000 old: %s new: %s\n",
                             base, size, mtrr_attrib_to_str(ltype),
                             mtrr_attrib_to_str(type));
                        goto out;
                }
                if (increment)
                        ++mtrr_usage_table[i];
                error = i;
                goto out;
        }
        /*  Search for an empty MTRR  */
        i = mtrr_if->get_free_region(base, size, replace);
        if (i >= 0) {
                set_mtrr(i, base, size, type);
                if (likely(replace < 0)) {
                        mtrr_usage_table[i] = 1;
                } else {
                        mtrr_usage_table[i] = mtrr_usage_table[replace];
                        if (increment)
                                mtrr_usage_table[i]++;
                        if (unlikely(replace != i)) {
                                set_mtrr(replace, 0, 0, 0);
                                mtrr_usage_table[replace] = 0;
                        }
                }
        } else
                printk(KERN_INFO "mtrr: no more MTRRs available\n");
        error = i;
 out:
        mutex_unlock(&mtrr_mutex);
        put_online_cpus();
        return error;
}

static int mtrr_check(unsigned long base, unsigned long size)
{
        if ((base & (PAGE_SIZE - 1)) || (size & (PAGE_SIZE - 1))) {
                printk(KERN_WARNING
                        "mtrr: size and base must be multiples of 4 kiB\n");
                printk(KERN_DEBUG
                        "mtrr: size: 0x%lx  base: 0x%lx\n", size, base);
                dump_stack();
                return -1;
        }
        return 0;
}

/**
 *      mtrr_add - Add a memory type region
 *      @base: Physical base address of region
 *      @size: Physical size of region
 *      @type: Type of MTRR desired
 *      @increment: If this is true do usage counting on the region
 *
 *      Memory type region registers control the caching on newer Intel and
 *      non Intel processors. This function allows drivers to request an
 *      MTRR is added. The details and hardware specifics of each processor's
 *      implementation are hidden from the caller, but nevertheless the 
 *      caller should expect to need to provide a power of two size on an
 *      equivalent power of two boundary.
 *
 *      If the region cannot be added either because all regions are in use
 *      or the CPU cannot support it a negative value is returned. On success
 *      the register number for this entry is returned, but should be treated
 *      as a cookie only.
 *
 *      On a multiprocessor machine the changes are made to all processors.
 *      This is required on x86 by the Intel processors.
 *
 *      The available types are
 *
 *      %MTRR_TYPE_UNCACHABLE   -       No caching
 *
 *      %MTRR_TYPE_WRBACK       -       Write data back in bursts whenever
 *
 *      %MTRR_TYPE_WRCOMB       -       Write data back soon but allow bursts
 *
 *      %MTRR_TYPE_WRTHROUGH    -       Cache reads but not writes
 *
 *      BUGS: Needs a quiet flag for the cases where drivers do not mind
 *      failures and do not wish system log messages to be sent.
 */

int
mtrr_add(unsigned long base, unsigned long size, unsigned int type,
         bool increment)
{
        if (mtrr_check(base, size))
                return -EINVAL;
        return mtrr_add_page(base >> PAGE_SHIFT, size >> PAGE_SHIFT, type,
                             increment);
}

/**
 *      mtrr_del_page - delete a memory type region
 *      @reg: Register returned by mtrr_add
 *      @base: Physical base address
 *      @size: Size of region
 *
 *      If register is supplied then base and size are ignored. This is
 *      how drivers should call it.
 *
 *      Releases an MTRR region. If the usage count drops to zero the 
 *      register is freed and the region returns to default state.
 *      On success the register is returned, on failure a negative error
 *      code.
 */

int mtrr_del_page(int reg, unsigned long base, unsigned long size)
{
        int i, max;
        mtrr_type ltype;
        unsigned long lbase, lsize;
        int error = -EINVAL;

        if (!mtrr_if)
                return -ENXIO;

        max = num_var_ranges;
        /* No CPU hotplug when we change MTRR entries */
        get_online_cpus();
        mutex_lock(&mtrr_mutex);
        if (reg < 0) {
                /*  Search for existing MTRR  */
                for (i = 0; i < max; ++i) {
                        mtrr_if->get(i, &lbase, &lsize, &ltype);
                        if (lbase == base && lsize == size) {
                                reg = i;
                                break;
                        }
                }
                if (reg < 0) {
                        printk(KERN_DEBUG "mtrr: no MTRR for %lx000,%lx000 found\n", base,
                               size);
                        goto out;
                }
        }
        if (reg >= max) {
                printk(KERN_WARNING "mtrr: register: %d too big\n", reg);
                goto out;
        }
        mtrr_if->get(reg, &lbase, &lsize, &ltype);
        if (lsize < 1) {
                printk(KERN_WARNING "mtrr: MTRR %d not used\n", reg);
                goto out;
        }
        if (mtrr_usage_table[reg] < 1) {
                printk(KERN_WARNING "mtrr: reg: %d has count=0\n", reg);
                goto out;
        }
        if (--mtrr_usage_table[reg] < 1)
                set_mtrr(reg, 0, 0, 0);
        error = reg;
 out:
        mutex_unlock(&mtrr_mutex);
        put_online_cpus();
        return error;
}
/**
 *      mtrr_del - delete a memory type region
 *      @reg: Register returned by mtrr_add
 *      @base: Physical base address
 *      @size: Size of region
 *
 *      If register is supplied then base and size are ignored. This is
 *      how drivers should call it.
 *
 *      Releases an MTRR region. If the usage count drops to zero the 
 *      register is freed and the region returns to default state.
 *      On success the register is returned, on failure a negative error
 *      code.
 */

int
mtrr_del(int reg, unsigned long base, unsigned long size)
{
        if (mtrr_check(base, size))
                return -EINVAL;
        return mtrr_del_page(reg, base >> PAGE_SHIFT, size >> PAGE_SHIFT);
}

EXPORT_SYMBOL(mtrr_add);
EXPORT_SYMBOL(mtrr_del);

/* HACK ALERT!
 * These should be called implicitly, but we can't yet until all the initcall
 * stuff is done...
 */
static void __init init_ifs(void)
{
#ifndef CONFIG_X86_64
        amd_init_mtrr();
        cyrix_init_mtrr();
        centaur_init_mtrr();
#endif
}

/* The suspend/resume methods are only for CPU without MTRR. CPU using generic
 * MTRR driver doesn't require this
 */
struct mtrr_value {
        mtrr_type       ltype;
        unsigned long   lbase;
        unsigned long   lsize;
};

static struct mtrr_value mtrr_state[MAX_VAR_RANGES];

static int mtrr_save(struct sys_device * sysdev, pm_message_t state)
{
        int i;

        for (i = 0; i < num_var_ranges; i++) {
                mtrr_if->get(i,
                             &mtrr_state[i].lbase,
                             &mtrr_state[i].lsize,
                             &mtrr_state[i].ltype);
        }
        return 0;
}

static int mtrr_restore(struct sys_device * sysdev)
{
        int i;

        for (i = 0; i < num_var_ranges; i++) {
                if (mtrr_state[i].lsize) 
                        set_mtrr(i,
                                 mtrr_state[i].lbase,
                                 mtrr_state[i].lsize,
                                 mtrr_state[i].ltype);
        }
        return 0;
}



static struct sysdev_driver mtrr_sysdev_driver = {
        .suspend        = mtrr_save,
        .resume         = mtrr_restore,
};

#ifdef CONFIG_MTRR_SANITIZER

#ifdef CONFIG_MTRR_SANITIZER_ENABLE_DEFAULT
static int enable_mtrr_cleanup __initdata = 1;
#else
static int enable_mtrr_cleanup __initdata;
#endif

#else

static int enable_mtrr_cleanup __initdata = -1;

#endif

static int __init disable_mtrr_cleanup_setup(char *str)
{
        if (enable_mtrr_cleanup != -1)
                enable_mtrr_cleanup = 0;
        return 0;
}
early_param("disable_mtrr_cleanup", disable_mtrr_cleanup_setup);

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

#define RANGE_NUM 256

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

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

        if (!merge)
                goto addit;

        /* 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;
        }

addit:
        /* need to add that */
        if (nr_range >= RANGE_NUM)
                return nr_range;

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

        nr_range++;

        return nr_range;

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

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

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

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

        address_mask_high = ((1u << (address_bits - 32u)) - 1u);

        base_hi = basek >> 22;
        base_lo  = basek << 10;

        if (sizek < 4*1024*1024) {
                mask_hi = address_mask_high;
                mask_lo = ~((sizek << 10) - 1);
        } else {
                mask_hi = address_mask_high & (~((sizek >> 22) - 1));
                mask_lo = 0;
        }

        base_lo |= type;
        mask_lo |= 0x800;
        fill_mtrr_var_range(reg, base_lo, base_hi, mask_lo, mask_hi);
}

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

        while (range_sizek) {
                unsigned long max_align, align;
                unsigned long sizek;
                /* Compute the maximum size I 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;
                printk(KERN_INFO "Setting variable MTRR %d, base: %ldMB, range: %ldMB, type %s\n",
                        reg, range_startk >> 10, sizek >> 10,
                        (type == MTRR_TYPE_UNCACHABLE)?"UC":
                            ((type == MTRR_TYPE_WRBACK)?"WB":"Other")
                        );
                set_var_mtrr(reg++, range_startk, sizek, type, address_bits);
                range_startk += sizek;
                range_sizek -= sizek;
                if (reg >= num_var_ranges)
                        break;
        }
        return reg;
}

static void __init range_to_mtrr_with_hole(struct var_mtrr_state *state, unsigned long basek)
{
        unsigned long hole_basek, hole_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;
        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;
        range_sizek = ALIGN(state->range_sizek - (range_basek - state->range_startk), gran_sizek);

        while (range_basek + range_sizek > (state->range_startk + state->range_sizek)) {
                range_sizek -= gran_sizek;
                if (!range_sizek)
                        return;
        }
        state->range_startk = range_basek;
        state->range_sizek = range_sizek;

        /* try to append some small hole */
        range0_basek = state->range_startk;
        range0_sizek = ALIGN(state->range_sizek, chunk_sizek);
        if ((range0_sizek == state->range_sizek) ||
            ((range0_basek + range0_sizek - chunk_sizek > basek) && basek)) {
                        printk(KERN_INFO "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, state->address_bits);
                return;
        }


        range0_sizek -= chunk_sizek;
        printk(KERN_INFO "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, state->address_bits);

        range_basek = range0_basek + range0_sizek;
        range_sizek = chunk_sizek;
        if (range_sizek - (state->range_sizek - range0_sizek) < (chunk_sizek >> 1)) {
                hole_sizek = range_sizek - (state->range_sizek - range0_sizek);
                hole_basek = range_basek + range_sizek - hole_sizek;
        } else
                range_sizek = state->range_sizek - range0_sizek;

        printk(KERN_INFO "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, state->address_bits);
        if (hole_sizek) {
                printk(KERN_INFO "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, state->address_bits);
        }
}

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

        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) {
                range_to_mtrr_with_hole(state, basek);

                state->range_startk = 0;
                state->range_sizek = 0;
        }
        /* Allocate an msr */
        state->range_startk = basek;
        state->range_sizek  = 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);

/* granity of mtrr of block */
static u64 mtrr_gran_size __initdata = (64ULL<<20);

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 void __init x86_setup_var_mtrrs(struct res_range *range, int nr_range, unsigned address_bits)
{
        struct var_mtrr_state var_state;
        int i;

        var_state.range_startk = 0;
        var_state.range_sizek = 0;
        var_state.reg = 0;
        var_state.address_bits = address_bits;
        var_state.chunk_sizek = mtrr_chunk_size >> 10;
        var_state.gran_sizek = mtrr_gran_size >> 10;

        /* Write the range etc */
        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 */
        range_to_mtrr_with_hole(&var_state, 0);
        printk(KERN_INFO "DONE variable MTRRs\n");
        /* Clear out the extra MTRR's */
        while (var_state.reg < num_var_ranges)
                set_var_mtrr(var_state.reg++, 0, 0, 0, var_state.address_bits);
}

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 i, base, size;
        mtrr_type type;

        for (i = 0; i < num_var_ranges; i++) {
                mtrr_if->get(i, &base, &size, &type);
                if (type != MTRR_TYPE_WRBACK)
                        continue;
                nr_range = add_range(range, nr_range, base, base + size - 1, 1);
        }
        printk(KERN_INFO "After WB checking\n");
        for (i = 0; i < nr_range; i++)
                printk(KERN_INFO "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++) {
                mtrr_if->get(i, &base, &size, &type);
                if (type != MTRR_TYPE_UNCACHABLE)
                        continue;
                if (!size)
                        continue;
                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++;
        }
        printk(KERN_INFO "After UC checking\n");
        for (i = 0; i < nr_range; i++)
                printk(KERN_INFO "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);
        printk(KERN_INFO "After sorting\n");
        for (i = 0; i < nr_range; i++)
                printk(KERN_INFO "MTRR MAP PFN: %016lx - %016lx\n", range[i].start, range[i].end + 1);

        return nr_range;
}

static int __init mtrr_cleanup(unsigned address_bits)
{
        unsigned long i, base, size, def, dummy;
        mtrr_type type;
        struct res_range range[RANGE_NUM];
        int nr_range;
        unsigned long extra_remove_base, extra_remove_size;

        /* extra one for all 0 */
        int num[MTRR_NUM_TYPES + 1];

        if (!is_cpu(INTEL) || enable_mtrr_cleanup < 1)
                return 0;
        rdmsr(MTRRdefType_MSR, def, dummy);
        def &= 0xff;
        if (def != MTRR_TYPE_UNCACHABLE)
                return 0;

        /* check entries number */
        memset(num, 0, sizeof(num));
        for (i = 0; i < num_var_ranges; i++) {
                mtrr_if->get(i, &base, &size, &type);
                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;

        memset(range, 0, sizeof(range));
        extra_remove_size = 0;
        if (mtrr_tom2) {
                extra_remove_base = 1 << (32 - PAGE_SHIFT);
                extra_remove_size = (mtrr_tom2>>PAGE_SHIFT) - extra_remove_base;
        }
        nr_range = x86_get_mtrr_mem_range(range, 0, extra_remove_base, extra_remove_size);

        /* convert ranges to var ranges state */
        x86_setup_var_mtrrs(range, nr_range, address_bits);

        return 1;

}

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 update_memory_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;
        struct res_range range[RANGE_NUM];
        int nr_range;
        u64 total_real_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(MTRRdefType_MSR, def, dummy);
        def &= 0xff;
        if (def != MTRR_TYPE_UNCACHABLE)
                return 0;

        /* Find highest cached pfn */
        for (i = 0; i < num_var_ranges; i++) {
                mtrr_if->get(i, &base, &size, &type);
                if (type != MTRR_TYPE_WRBACK)
                        continue;
                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) {
                if (!kvm_para_available()) {
                        printk(KERN_WARNING
                                "WARNING: strange, CPU MTRRs all blank?\n");
                        WARN_ON(1);
                }
                return 0;
        }

        /* check entries number */
        memset(num, 0, sizeof(num));
        for (i = 0; i < num_var_ranges; i++) {
                mtrr_if->get(i, &base, &size, &type);
                if (type >= MTRR_NUM_TYPES)
                        continue;
                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);

        total_real_trim_size = 0;
        /* check the head */
        if (range[0].start)
                total_real_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_real_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_real_trim_size += real_trim_memory(range[i].end + 1, end_pfn);

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

                if (enable_mtrr_cleanup < 1)
                        WARN_ON(1);

                printk(KERN_INFO "update e820 for mtrr\n");
                update_e820();

                return 1;
        }

        return 0;
}

/**
 * mtrr_bp_init - initialize mtrrs on the boot CPU
 *
 * This needs to be called early; before any of the other CPUs are 
 * initialized (i.e. before smp_init()).
 * 
 */
void __init mtrr_bp_init(void)
{
        u32 phys_addr;
        init_ifs();

        phys_addr = 32;

        if (cpu_has_mtrr) {
                mtrr_if = &generic_mtrr_ops;
                size_or_mask = 0xff000000;      /* 36 bits */
                size_and_mask = 0x00f00000;
                phys_addr = 36;

                /* This is an AMD specific MSR, but we assume(hope?) that
                   Intel will implement it to when they extend the address
                   bus of the Xeon. */
                if (cpuid_eax(0x80000000) >= 0x80000008) {
                        phys_addr = cpuid_eax(0x80000008) & 0xff;
                        /* CPUID workaround for Intel 0F33/0F34 CPU */
                        if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
                            boot_cpu_data.x86 == 0xF &&
                            boot_cpu_data.x86_model == 0x3 &&
                            (boot_cpu_data.x86_mask == 0x3 ||
                             boot_cpu_data.x86_mask == 0x4))
                                phys_addr = 36;

                        size_or_mask = ~((1ULL << (phys_addr - PAGE_SHIFT)) - 1);
                        size_and_mask = ~size_or_mask & 0xfffff00000ULL;
                } else if (boot_cpu_data.x86_vendor == X86_VENDOR_CENTAUR &&
                           boot_cpu_data.x86 == 6) {
                        /* VIA C* family have Intel style MTRRs, but
                           don't support PAE */
                        size_or_mask = 0xfff00000;      /* 32 bits */
                        size_and_mask = 0;
                        phys_addr = 32;
                }
        } else {
                switch (boot_cpu_data.x86_vendor) {
                case X86_VENDOR_AMD:
                        if (cpu_has_k6_mtrr) {
                                /* Pre-Athlon (K6) AMD CPU MTRRs */
                                mtrr_if = mtrr_ops[X86_VENDOR_AMD];
                                size_or_mask = 0xfff00000;      /* 32 bits */
                                size_and_mask = 0;
                        }
                        break;
                case X86_VENDOR_CENTAUR:
                        if (cpu_has_centaur_mcr) {
                                mtrr_if = mtrr_ops[X86_VENDOR_CENTAUR];
                                size_or_mask = 0xfff00000;      /* 32 bits */
                                size_and_mask = 0;
                        }
                        break;
                case X86_VENDOR_CYRIX:
                        if (cpu_has_cyrix_arr) {
                                mtrr_if = mtrr_ops[X86_VENDOR_CYRIX];
                                size_or_mask = 0xfff00000;      /* 32 bits */
                                size_and_mask = 0;
                        }
                        break;
                default:
                        break;
                }
        }

        if (mtrr_if) {
                set_num_var_ranges();
                init_table();
                if (use_intel()) {
                        get_mtrr_state();

                        if (mtrr_cleanup(phys_addr))
                                mtrr_if->set_all();

                }
        }
}

void mtrr_ap_init(void)
{
        unsigned long flags;

        if (!mtrr_if || !use_intel())
                return;
        /*
         * Ideally we should hold mtrr_mutex here to avoid mtrr entries changed,
         * but this routine will be called in cpu boot time, holding the lock
         * breaks it. This routine is called in two cases: 1.very earily time
         * of software resume, when there absolutely isn't mtrr entry changes;
         * 2.cpu hotadd time. We let mtrr_add/del_page hold cpuhotplug lock to
         * prevent mtrr entry changes
         */
        local_irq_save(flags);

        mtrr_if->set_all();

        local_irq_restore(flags);
}

/**
 * Save current fixed-range MTRR state of the BSP
 */
void mtrr_save_state(void)
{
        smp_call_function_single(0, mtrr_save_fixed_ranges, NULL, 1, 1);
}

static int __init mtrr_init_finialize(void)
{
        if (!mtrr_if)
                return 0;
        if (use_intel()) {
                if (enable_mtrr_cleanup < 1)
                        mtrr_state_warn();
        } else {
                /* The CPUs haven't MTRR and seem to not support SMP. They have
                 * specific drivers, we use a tricky method to support
                 * suspend/resume for them.
                 * TBD: is there any system with such CPU which supports
                 * suspend/resume?  if no, we should remove the code.
                 */
                sysdev_driver_register(&cpu_sysdev_class,
                        &mtrr_sysdev_driver);
        }
        return 0;
}
subsys_initcall(mtrr_init_finialize);