x86: mtrr_cleanup optimization, v2

fix hpa's t61 with 4g ram:

   change layout from
	(n - 1)*chunksize + chunk_size - NC
   to
	n*chunksize - NC

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 37 insertions, 42 deletions

diff --git a/arch/x86/kernel/cpu/mtrr/main.c b/arch/x86/kernel/cpu/mtrr/main.c
index cc135572882..93d575ac61a 100644
--- a/arch/x86/kernel/cpu/mtrr/main.c
+++ b/arch/x86/kernel/cpu/mtrr/main.c
@@ -970,6 +970,8 @@ range_to_mtrr_with_hole(struct var_mtrr_state *state, unsigned long basek,
         /* try to append some small hole */
         range0_basek = state->range_startk;
         range0_sizek = ALIGN(state->range_sizek, chunk_sizek);
+
+        /* no increase */
         if (range0_sizek == state->range_sizek) {
                 if (debug_print)
                         printk(KERN_DEBUG "rangeX: %016lx - %016lx\n",
@@ -980,13 +982,13 @@ range_to_mtrr_with_hole(struct var_mtrr_state *state, unsigned long basek,
                 return 0;
         }
 
-        range0_sizek -= chunk_sizek;
-        if (range0_sizek && sizek) {
-            while (range0_basek + range0_sizek > (basek + sizek)) {
-                range0_sizek -= chunk_sizek;
-                if (!range0_sizek)
-                        break;
-            }
+        /* only cut back, when it is not the last */
+        if (sizek) {
+                while (range0_basek + range0_sizek > (basek + sizek)) {
+                        range0_sizek -= chunk_sizek;
+                        if (!range0_sizek)
+                                break;
+                }
         }
 
         if (range0_sizek) {
@@ -1000,46 +1002,39 @@ range_to_mtrr_with_hole(struct var_mtrr_state *state, unsigned long basek,
         }
 
         range_basek = range0_basek + range0_sizek;
-        range_sizek = chunk_sizek;
 
-        if (range_basek + range_sizek > basek &&
-            range_basek + range_sizek <= (basek + sizek)) {
-                /* one hole */
-                second_basek = basek;
-                second_sizek = range_basek + range_sizek - basek;
-        }
+        /* one hole in the middle */
+        if (range_basek > basek && range_basek <= (basek + sizek))
+                second_sizek = range_basek - basek;
 
-        /* if last piece, only could one hole near end */
-        if ((second_basek || !basek) &&
-            range_sizek - (state->range_sizek - range0_sizek) - second_sizek <
-            (chunk_sizek >> 1)) {
-                /*
-                 * one hole in middle (second_sizek is 0) or at end
-                 * (second_sizek is 0 )
-                 */
-                hole_sizek = range_sizek - (state->range_sizek - range0_sizek)
-                                 - second_sizek;
-                hole_basek = range_basek + range_sizek - hole_sizek
-                                 - second_sizek;
-        } else {
-                /* fallback for big hole, or several holes */
+        if (range0_sizek > state->range_sizek) {
+                unsigned long hole_basek, hole_sizek;
+
+                /* one hole in middle or at end */
+                hole_sizek = range0_sizek - state->range_sizek - second_sizek;
+                if (hole_sizek) {
+                        hole_basek = range_basek - hole_sizek - second_sizek;
+                        if (debug_print)
+                                printk(KERN_DEBUG "hole: %016lx - %016lx\n",
+                                         hole_basek<<10,
+                                         (hole_basek + hole_sizek)<<10);
+                        state->reg = range_to_mtrr(state->reg, hole_basek,
+                                                   hole_sizek,
+                                                   MTRR_TYPE_UNCACHABLE);
+                }
+        } else  {
+                /* need to handle left over */
                 range_sizek = state->range_sizek - range0_sizek;
-                second_basek = 0;
-                second_sizek = 0;
-        }
 
-        if (debug_print)
-                printk(KERN_DEBUG "range: %016lx - %016lx\n", range_basek<<10,
-                         (range_basek + range_sizek)<<10);
-        state->reg = range_to_mtrr(state->reg, range_basek, range_sizek,
+                if (range_sizek) {
+                        if (debug_print)
+                                printk(KERN_DEBUG "range: %016lx - %016lx\n",
+                                         range_basek<<10,
+                                         (range_basek + range_sizek)<<10);
+                        state->reg = range_to_mtrr(state->reg, range_basek,
+                                         range_sizek,
                                          MTRR_TYPE_WRBACK);
-        if (hole_sizek) {
-                if (debug_print)
-                        printk(KERN_DEBUG "hole: %016lx - %016lx\n",
-                                 hole_basek<<10, (hole_basek + hole_sizek)<<10);
-                state->reg = range_to_mtrr(state->reg, hole_basek, hole_sizek,
-                                                 MTRR_TYPE_UNCACHABLE);
-
+                }
         }
 
         return second_sizek;