x86, mtrr: Refactor MTRR type overlap check code
Move the MTRR type overlap check into a new function. No functional change in
this patch. Just making it easier to add multiple region overlap check in
the following patch.
Signed-off-by: Venkatesh Pallipadi <venki@google.com>
LKML-Reference: <1284159350-19841-2-git-send-email-venki@google.com>
Reviewed-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c
index 7d28d7d..14f4f0c 100644
--- a/arch/x86/kernel/cpu/mtrr/generic.c
+++ b/arch/x86/kernel/cpu/mtrr/generic.c
@@ -65,6 +65,33 @@
}
/*
+ * Check and return the effective type for MTRR-MTRR type overlap.
+ * Returns 1 if the effective type is UNCACHEABLE, else returns 0
+ */
+static int check_type_overlap(u8 *prev, u8 *curr)
+{
+ if (*prev == MTRR_TYPE_UNCACHABLE || *curr == MTRR_TYPE_UNCACHABLE) {
+ *prev = MTRR_TYPE_UNCACHABLE;
+ *curr = MTRR_TYPE_UNCACHABLE;
+ return 1;
+ }
+
+ if ((*prev == MTRR_TYPE_WRBACK && *curr == MTRR_TYPE_WRTHROUGH) ||
+ (*prev == MTRR_TYPE_WRTHROUGH && *curr == MTRR_TYPE_WRBACK)) {
+ *prev = MTRR_TYPE_WRTHROUGH;
+ *curr = MTRR_TYPE_WRTHROUGH;
+ }
+
+ if (*prev != *curr) {
+ *prev = MTRR_TYPE_UNCACHABLE;
+ *curr = MTRR_TYPE_UNCACHABLE;
+ return 1;
+ }
+
+ return 0;
+}
+
+/*
* Returns the effective MTRR type for the region
* Error returns:
* - 0xFE - when the range is "not entirely covered" by _any_ var range MTRR
@@ -138,21 +165,8 @@
continue;
}
- if (prev_match == MTRR_TYPE_UNCACHABLE ||
- curr_match == MTRR_TYPE_UNCACHABLE) {
- return MTRR_TYPE_UNCACHABLE;
- }
-
- if ((prev_match == MTRR_TYPE_WRBACK &&
- curr_match == MTRR_TYPE_WRTHROUGH) ||
- (prev_match == MTRR_TYPE_WRTHROUGH &&
- curr_match == MTRR_TYPE_WRBACK)) {
- prev_match = MTRR_TYPE_WRTHROUGH;
- curr_match = MTRR_TYPE_WRTHROUGH;
- }
-
- if (prev_match != curr_match)
- return MTRR_TYPE_UNCACHABLE;
+ if (check_type_overlap(&prev_match, &curr_match))
+ return curr_match;
}
if (mtrr_tom2) {
