5 files changed, 528 insertions, 14 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index e07c432c731f..44427607b7c6 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -599,6 +599,20 @@ and is between 256 and 4096 characters. It is defined in the file
                         See drivers/char/README.epca and
                         Documentation/digiepca.txt.
 
+        disable_mtrr_cleanup [X86]
+        enable_mtrr_cleanup [X86]
+                        The kernel tries to adjust MTRR layout from continuous
+                        to discrete, to make X server driver able to add WB
+                        entry later. This parameter enables/disables that.
+
+        mtrr_chunk_size=nn[KMG] [X86]
+                        used for mtrr cleanup. It is largest continous chunk
+                        that could hold holes aka. UC entries.
+
+        mtrr_gran_size=nn[KMG] [X86]
+                        used for mtrr cleanup. It is granity of mtrr block.
+                        Big value could prevent small alignment use up MTRRs.
+
         disable_mtrr_trim [X86, Intel and AMD only]
                         By default the kernel will trim any uncacheable
                         memory out of your available memory pool based on
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index fe361ae7ef2f..97a1764a3d20 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1092,6 +1092,32 @@ config MTRR
 
           See <file:Documentation/mtrr.txt> for more information.
 
+config MTRR_SANITIZER
+        def_bool y
+        prompt "MTRR cleanup support"
+        depends on MTRR
+        help
+          Convert MTRR layout from continuous to discrete, so some X driver
+          could add WB entries.
+
+          Say N here if you see bootup problems (boot crash, boot hang,
+          spontaneous reboots).
+
+          Could be disabled with disable_mtrr_cleanup. Also mtrr_chunk_size
+          could be used to send largest mtrr entry size for continuous block
+          to hold holes (aka. UC entries)
+
+          If unsure, say Y.
+
+config MTRR_SANITIZER_ENABLE_DEFAULT
+        def_bool y
+        prompt "Enable MTRR cleanup by default"
+        depends on MTRR_SANITIZER
+        help
+          Enable mtrr cleanup by default
+
+          If unsure, say Y.
+
 config X86_PAT
         bool
         prompt "x86 PAT support"
diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c
index 0625d4158e58..5aae648600bf 100644
--- a/arch/x86/kernel/cpu/mtrr/generic.c
+++ b/arch/x86/kernel/cpu/mtrr/generic.c
@@ -37,7 +37,7 @@ static struct fixed_range_block fixed_range_blocks[] = {
 static unsigned long smp_changes_mask;
 static struct mtrr_state mtrr_state = {};
 static int mtrr_state_set;
-static u64 tom2;
+u64 mtrr_tom2;
 
 #undef MODULE_PARAM_PREFIX
 #define MODULE_PARAM_PREFIX "mtrr."
@@ -139,8 +139,8 @@ u8 mtrr_type_lookup(u64 start, u64 end)
                 }
         }
 
-        if (tom2) {
-                if (start >= (1ULL<<32) && (end < tom2))
+        if (mtrr_tom2) {
+                if (start >= (1ULL<<32) && (end < mtrr_tom2))
                         return MTRR_TYPE_WRBACK;
         }
 
@@ -158,6 +158,20 @@ get_mtrr_var_range(unsigned int index, struct mtrr_var_range *vr)
         rdmsr(MTRRphysMask_MSR(index), vr->mask_lo, vr->mask_hi);
 }
 
+/*  fill the MSR pair relating to a var range  */
+void fill_mtrr_var_range(unsigned int index,
+                u32 base_lo, u32 base_hi, u32 mask_lo, u32 mask_hi)
+{
+        struct mtrr_var_range *vr;
+
+        vr = mtrr_state.var_ranges;
+
+        vr[index].base_lo = base_lo;
+        vr[index].base_hi = base_hi;
+        vr[index].mask_lo = mask_lo;
+        vr[index].mask_hi = mask_hi;
+}
+
 static void
 get_fixed_ranges(mtrr_type * frs)
 {
@@ -216,10 +230,10 @@ void __init get_mtrr_state(void)
                 unsigned low, high;
                 /* TOP_MEM2 */
                 rdmsr(MSR_K8_TOP_MEM2, low, high);
-                tom2 = high;
-                tom2 <<= 32;
-                tom2 |= low;
-                tom2 &= 0xffffff8000000ULL;
+                mtrr_tom2 = high;
+                mtrr_tom2 <<= 32;
+                mtrr_tom2 |= low;
+                mtrr_tom2 &= 0xffffff8000000ULL;
         }
         if (mtrr_show) {
                 int high_width;
@@ -251,9 +265,9 @@ void __init get_mtrr_state(void)
                         else
                                 printk(KERN_INFO "MTRR %u disabled\n", i);
                 }
-                if (tom2) {
+                if (mtrr_tom2) {
                         printk(KERN_INFO "TOM2: %016llx aka %lldM\n",
-                                          tom2, tom2>>20);
+                                          mtrr_tom2, mtrr_tom2>>20);
                 }
         }
         mtrr_state_set = 1;
diff --git a/arch/x86/kernel/cpu/mtrr/main.c b/arch/x86/kernel/cpu/mtrr/main.c
index 6a1e278d9323..8a6f68b45e3e 100644
--- a/arch/x86/kernel/cpu/mtrr/main.c
+++ b/arch/x86/kernel/cpu/mtrr/main.c
@@ -37,6 +37,7 @@
 #include <linux/smp.h>
 #include <linux/cpu.h>
 #include <linux/mutex.h>
+#include <linux/sort.h>
 
 #include <asm/e820.h>
 #include <asm/mtrr.h>
@@ -609,6 +610,452 @@ static struct sysdev_driver mtrr_sysdev_driver = {
         .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)
@@ -729,18 +1176,21 @@ int __init mtrr_trim_uncached_memory(unsigned long end_pfn)
  */
 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) {
-                        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 &&
@@ -758,6 +1208,7 @@ void __init mtrr_bp_init(void)
                            don't support PAE */
                         size_or_mask = 0xfff00000;      /* 32 bits */
                         size_and_mask = 0;
+                        phys_addr = 32;
                 }
         } else {
                 switch (boot_cpu_data.x86_vendor) {
@@ -791,8 +1242,13 @@ void __init mtrr_bp_init(void)
         if (mtrr_if) {
                 set_num_var_ranges();
                 init_table();
-                if (use_intel())
+                if (use_intel()) {
                         get_mtrr_state();
+
+                        if (mtrr_cleanup(phys_addr))
+                                mtrr_if->set_all();
+
+                }
         }
 }
 
@@ -829,9 +1285,10 @@ static int __init mtrr_init_finialize(void)
 {
         if (!mtrr_if)
                 return 0;
-        if (use_intel())
-                mtrr_state_warn();
-        else {
+        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.
diff --git a/arch/x86/kernel/cpu/mtrr/mtrr.h b/arch/x86/kernel/cpu/mtrr/mtrr.h
index 2cc77eb6fea3..2dc4ec656b23 100644
--- a/arch/x86/kernel/cpu/mtrr/mtrr.h
+++ b/arch/x86/kernel/cpu/mtrr/mtrr.h
@@ -81,6 +81,8 @@ void set_mtrr_done(struct set_mtrr_context *ctxt);
 void set_mtrr_cache_disable(struct set_mtrr_context *ctxt);
 void set_mtrr_prepare_save(struct set_mtrr_context *ctxt);
 
+void fill_mtrr_var_range(unsigned int index,
+                u32 base_lo, u32 base_hi, u32 mask_lo, u32 mask_hi);
 void get_mtrr_state(void);
 
 extern void set_mtrr_ops(struct mtrr_ops * ops);
@@ -92,6 +94,7 @@ extern struct mtrr_ops * mtrr_if;
 #define use_intel()     (mtrr_if && mtrr_if->use_intel_if == 1)
 
 extern unsigned int num_var_ranges;
+extern u64 mtrr_tom2;
 
 void mtrr_state_warn(void);
 const char *mtrr_attrib_to_str(int x);