When an MTRR entry is inclusive to a requested range, i.e.
the start and end of the request are not within the MTRR
entry range but the range contains the MTRR entry entirely,
__mtrr_type_lookup() ignores such case because both
start_state and end_state are set to zero.
This patch fixes the issue by adding a new flag, inclusive,
to detect the case. This case is then handled in the same
way as (!start_state && end_state).
Also updated the comment in __mtrr_type_lookup() to clarify
that the repeat handling is necessary to handle overlaps
with the default type, since overlaps with multiple entries
alone can be handled without such repeat.
Signed-off-by: Toshi Kani <toshi.kani@xxxxxx>
---
arch/x86/kernel/cpu/mtrr/generic.c | 20 +++++++++++---------
1 file changed, 11 insertions(+), 9 deletions(-)
diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c
index 7d74f7b..cdb955f 100644
--- a/arch/x86/kernel/cpu/mtrr/generic.c
+++ b/arch/x86/kernel/cpu/mtrr/generic.c
@@ -154,7 +154,7 @@ static u8 __mtrr_type_lookup(u64 start, u64 end, u64 *partial_end, int *repeat)
prev_match = 0xFF;
for (i = 0; i < num_var_ranges; ++i) {
- unsigned short start_state, end_state;
+ unsigned short start_state, end_state, inclusive;
if (!(mtrr_state.var_ranges[i].mask_lo & (1 << 11)))
continue;
@@ -166,20 +166,22 @@ static u8 __mtrr_type_lookup(u64 start, u64 end, u64 *partial_end, int *repeat)
start_state = ((start & mask) == (base & mask));
end_state = ((end & mask) == (base & mask));
+ inclusive = ((start < base) && (end > base));
- if (start_state != end_state) {
+ if ((start_state != end_state) || inclusive) {
/*
* We have start:end spanning across an MTRR.
- * We split the region into
- * either
- * (start:mtrr_end) (mtrr_end:end)
- * or
- * (start:mtrr_start) (mtrr_start:end)
+ * We split the region into either
+ * - start_state:1
+ * (start:mtrr_end) (mtrr_end:end)
+ * - end_state:1 or inclusive:1
+ * (start:mtrr_start) (mtrr_start:end)
* depending on kind of overlap.
* Return the type for first region and a pointer to
* the start of second region so that caller will
* lookup again on the second region.
- * Note: This way we handle multiple overlaps as well.
+ * Note: This way we handle overlaps with multiple
+ * entries and the default type properly.
*/
if (start_state)
*partial_end = base + get_mtrr_size(mask);
@@ -195,7 +197,7 @@ static u8 __mtrr_type_lookup(u64 start, u64 end, u64 *partial_end, int *repeat)
*repeat = 1;
}
- if ((start & mask) != (base & mask))
+ if (!start_state)
continue;
curr_match = mtrr_state.var_ranges[i].base_lo & 0xff;
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>