[PATCH] x86: workaroun mtrr mask setting

Some BIOS doesn't set mtrr mask correctly, workaround it be prefix 111

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>

diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c
index 509bd3d..a17d5ba 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;
+	/* expend tmp with high bits to all 1s*/
+	hi = fls(tmp);
+	if (hi > 0) {
+		tmp |= ~((1<<(hi - 1)) - 1);
+
+		if (tmp != mask_lo) {
+			WARN_ON("You BIOS mask set is wrong, complain to vendor\n");
+			mask_lo = tmp;
+		}
+	}
 
 	/* This works correctly if size is a power of two, i.e. a
 	   contiguous range. */