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>

1 files changed, 29 insertions, 15 deletions

diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c
index 7d28d7d03885..14f4f0c0329a 100644
--- a/arch/x86/kernel/cpu/mtrr/generic.c
+++ b/arch/x86/kernel/cpu/mtrr/generic.c
@@ -65,6 +65,33 @@ static inline void k8_check_syscfg_dram_mod_en(void)
 }
 
 /*
+ * 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 @@ u8 mtrr_type_lookup(u64 start, u64 end)
                         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) {