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authorYinghai Lu <yhlu.kernel@gmail.com>2008-08-21 20:24:24 -0700
committerIngo Molnar <mingo@elte.hu>2008-08-22 05:49:35 +0200
commit38cc1c3df77c1bb739a4766788eb9fa49f16ffdf (patch)
tree5d817ca8a89cb6409fdbbce48aa49971c5612aee
parent8323444b5dba3fe55e56a95d20d8f55c1d6745af (diff)
x86: work around MTRR mask setting
Joshua Hoblitt reported that only 3 GB of his 16 GB of RAM is usable. Booting with mtrr_show showed us the BIOS-initialized MTRR settings - which are all wrong. So the root cause is that the BIOS has not set the mask correctly: > [ 0.429971] MSR00000200: 00000000d0000000 > [ 0.433305] MSR00000201: 0000000ff0000800 > should be ==> [ 0.433305] MSR00000201: 0000003ff0000800 > > [ 0.436638] MSR00000202: 00000000e0000000 > [ 0.439971] MSR00000203: 0000000fe0000800 > should be ==> [ 0.439971] MSR00000203: 0000003fe0000800 > > [ 0.443304] MSR00000204: 0000000000000006 > [ 0.446637] MSR00000205: 0000000c00000800 > should be ==> [ 0.446637] MSR00000205: 0000003c00000800 > > [ 0.449970] MSR00000206: 0000000400000006 > [ 0.453303] MSR00000207: 0000000fe0000800 > should be ==> [ 0.453303] MSR00000207: 0000003fe0000800 > > [ 0.456636] MSR00000208: 0000000420000006 > [ 0.459970] MSR00000209: 0000000ff0000800 > should be ==> [ 0.459970] MSR00000209: 0000003ff0000800 So detect this borkage and add the prefix 111. Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com> Cc: <stable@kernel.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--arch/x86/kernel/cpu/mtrr/generic.c15
1 files changed, 13 insertions, 2 deletions
diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c
index 509bd3d9eac..43102e03e2d 100644
--- a/arch/x86/kernel/cpu/mtrr/generic.c
+++ b/arch/x86/kernel/cpu/mtrr/generic.c
@@ -379,6 +379,7 @@ static void generic_get_mtrr(unsigned int reg, unsigned long *base,
unsigned long *size, mtrr_type *type)
{
unsigned int mask_lo, mask_hi, base_lo, base_hi;
+ unsigned int tmp, hi;
rdmsr(MTRRphysMask_MSR(reg), mask_lo, mask_hi);
if ((mask_lo & 0x800) == 0) {
@@ -392,8 +393,18 @@ static void generic_get_mtrr(unsigned int reg, unsigned long *base,
rdmsr(MTRRphysBase_MSR(reg), base_lo, base_hi);
/* Work out the shifted address mask. */
- mask_lo = size_or_mask | mask_hi << (32 - PAGE_SHIFT)
- | mask_lo >> PAGE_SHIFT;
+ tmp = mask_hi << (32 - PAGE_SHIFT) | mask_lo >> PAGE_SHIFT;
+ mask_lo = size_or_mask | tmp;
+ /* Expand tmp with high bits to all 1s*/
+ hi = fls(tmp);
+ if (hi > 0) {
+ tmp |= ~((1<<(hi - 1)) - 1);
+
+ if (tmp != mask_lo) {
+ WARN_ON("mtrr: your BIOS has set up an incorrect mask, fixing it up.\n");
+ mask_lo = tmp;
+ }
+ }
/* This works correctly if size is a power of two, i.e. a
contiguous range. */