linux/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, 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,
};

/* should be related to MTRR_VAR_RANGES nums */
#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)
{
	/* 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 that */
	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;
}

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

static struct var_mtrr_range_state __initdata range_state[RANGE_NUM];
static int __initdata debug_print;

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++) {
		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;
		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;
}

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

#ifdef CONFIG_MTRR_SANITIZER

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

	sum = 0;
	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)
{
	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("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);

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

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)
{
	char factor;
	unsigned long base = sizek;

	if (base & ((1<<10) - 1)) {
		/* not MB alignment */
		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 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;
		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),

			printk(KERN_DEBUG "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) {
		if (debug_print)
			printk(KERN_DEBUG "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 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) {
		if (debug_print)
			printk(KERN_DEBUG "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_sizek = state->range_sizek - range0_sizek;

		if (debug_print)
			printk(KERN_DEBUG "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;
		if (debug_print)
			printk(KERN_DEBUG "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);

/* granity 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 int 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 i;
	int num_reg;

	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 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 */
	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)
{
	int i;
	char start_factor = 'K', size_factor = 'K';
	unsigned long start_base, size_base;
	mtrr_type type;

	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 extra_remove_base,
					 unsigned long extra_remove_size,
					 int i)
{
	int num_reg;
	static struct res_range range_new[RANGE_NUM];
	static int nr_range_new;
	unsigned long range_sums_new;

	/* 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,
				extra_remove_base, extra_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)
{
	char gran_factor, chunk_factor, lose_factor;
	unsigned long gran_base, chunk_base, lose_base;

	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),
	printk(KERN_INFO "%sgran_size: %ld%c \tchunk_size: %ld%c \t",
			result[i].bad ? "*BAD*" : " ",
			gran_base, gran_factor, chunk_base, chunk_factor);
	printk(KERN_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 i;
	int num_reg_good;
	int index_good;

	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;
}


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

	if (!is_cpu(INTEL) || enable_mtrr_cleanup < 1)
		return 0;
	rdmsr(MTRRdefType_MSR, 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));
	extra_remove_size = 0;
	extra_remove_base = 1 << (32 - PAGE_SHIFT);
	if (mtrr_tom2)
		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);
	/*
	 * [0, 1M) should always be coverred by var mtrr with WB
	 * and fixed mtrrs should take effective 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 coverred: %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,
				      extra_remove_base, extra_remove_size, i);

		mtrr_print_out_one_result(i);

		if (!result[i].bad) {
			set_var_mtrr_all(address_bits);
			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,
				      extra_remove_base, extra_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
static int __init mtrr_cleanup(unsigned address_bits)
{
	return 0;
}
#endif

static int __initdata changed_by_mtrr_cleanup;

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(MTRRdefType_MSR, 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) {
		WARN(!kvm_para_available(), KERN_WARNING
				"WARNING: strange, CPU MTRRs all blank?\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);

	total_trim_size = 0;
	/* check the head */
	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) {
		printk(KERN_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);

		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)) {
				changed_by_mtrr_cleanup = 1;
				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);
}

static int __init mtrr_init_finialize(void)
{
	if (!mtrr_if)
		return 0;
	if (use_intel()) {
		if (!changed_by_mtrr_cleanup)
			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);