The patch titled
Subject: mtrr, x86: fix MTRR lookup to handle inclusive entry
has been removed from the -mm tree. Its filename was
mtrr-x86-fix-mtrr-lookup-to-handle-inclusive-entry.patch
This patch was dropped because an updated version will be merged
------------------------------------------------------
From: Toshi Kani <toshi.kani@xxxxxx>
Subject: mtrr, x86: fix MTRR lookup to handle inclusive entry
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 a case
because both start_state and end_state are set to zero.
This bug can cause the following issues:
1) reserve_memtype() tracks an effective memory type in case a request
type is WB (ex. /dev/mem blindly uses WB). Missing to track with its
effective type causes a subsequent request to map the same range with
the effective type to fail.
2) pud_set_huge() and pmd_set_huge() check if a requested range has any
overlap with MTRRs. Missing to detect an overlap may cause a
performance penalty or undefined behavior.
This patch fixes the bug by adding a new flag, 'inclusive', to detect the
inclusive case. This case is then handled in the same way as
(!start_state && end_state). With this fix, __mtrr_type_lookup() handles
the inclusive case properly.
Signed-off-by: Toshi Kani <toshi.kani@xxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
Cc: Robert Elliott <Elliott@xxxxxx>
Cc: Paul Bolle <pebolle@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/cpu/mtrr/generic.c | 17 +++++++++--------
1 file changed, 9 insertions(+), 8 deletions(-)
diff -puN arch/x86/kernel/cpu/mtrr/generic.c~mtrr-x86-fix-mtrr-lookup-to-handle-inclusive-entry arch/x86/kernel/cpu/mtrr/generic.c
--- a/arch/x86/kernel/cpu/mtrr/generic.c~mtrr-x86-fix-mtrr-lookup-to-handle-inclusive-entry
+++ a/arch/x86/kernel/cpu/mtrr/generic.c
@@ -154,7 +154,7 @@ static u8 __mtrr_type_lookup(u64 start,
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;
@@ -166,15 +166,16 @@ static u8 __mtrr_type_lookup(u64 start,
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
@@ -195,7 +196,7 @@ static u8 __mtrr_type_lookup(u64 start,
*repeat = 1;
}
- if ((start & mask) != (base & mask))
+ if (!start_state)
continue;
curr_match = mtrr_state.var_ranges[i].base_lo & 0xff;
_
Patches currently in -mm which might be from toshi.kani@xxxxxx are
linux-next.patch
mtrr-x86-fix-mtrr-state-checks-in-mtrr_type_lookup.patch
mtrr-x86-define-mtrr_type_invalid-for-mtrr_type_lookup.patch
mtrr-x86-clean-up-mtrr_type_lookup.patch
mtrr-mm-x86-enhance-mtrr-checks-for-kva-huge-page-mapping.patch
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