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linux/arch/x86/kernel/cpu/mtrr/main.c

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/* 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 <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,
};
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;
}
/**
* 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 trim_start, trim_size;
/*
* 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;
if (amd_special_default_mtrr())
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;
}
if (highest_pfn < end_pfn) {
printk(KERN_WARNING "WARNING: BIOS bug: CPU MTRRs don't cover"
" all of memory, losing %luMB of RAM.\n",
(end_pfn - highest_pfn) >> (20 - PAGE_SHIFT));
WARN_ON(1);
printk(KERN_INFO "update e820 for mtrr\n");
trim_start = highest_pfn;
trim_start <<= PAGE_SHIFT;
trim_size = end_pfn;
trim_size <<= PAGE_SHIFT;
trim_size -= trim_start;
update_memory_range(trim_start, trim_size, E820_RAM,
E820_RESERVED);
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)
{
init_ifs();
if (cpu_has_mtrr) {
mtrr_if = &generic_mtrr_ops;
size_or_mask = 0xff000000; /* 36 bits */
size_and_mask = 0x00f00000;
/* 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) {
u32 phys_addr;
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;
}
} 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();
}
}
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())
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);
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