x86/mm/mtrr: Fix MTRR lookup to handle an inclusive entry

[cascardo/linux.git] / arch / x86 / kernel / cpu / mtrr / generic.c

diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c
index 5b23967..e202d26 100644 (file)
--- 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;
@@ -166,19 +166,27 @@ 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
+                        * (start:mtrr_start)(mtrr_start:end)
+                        * - inclusive:1
+                        * (start:mtrr_start)(mtrr_start:mtrr_end)(mtrr_end: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.
+                        *
+                        * Return the type of the first region and a pointer
+                        * to the start of next region so that caller will be
+                        * advised to lookup again after having adjusted start
+                        * and end.
+                        *
                         * Note: This way we handle multiple overlaps as well.
                         */
                        if (start_state)