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Date: Thu, 21 Oct 2010 16:02:49 +0200
From: Ingo Molnar <mingo@...e.hu>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org, "H. Peter Anvin" <hpa@...or.com>,
Thomas Gleixner <tglx@...utronix.de>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: [GIT PULL] x86/mtrr changes for v2.6.37
Linus,
Please pull the latest x86-mtrr-for-linus git tree from:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git x86-mtrr-for-linus
Thanks,
Ingo
------------------>
Venkatesh Pallipadi (2):
x86, mtrr: Refactor MTRR type overlap check code
x86, mtrr: Support mtrr lookup for range spanning across MTRR range
arch/x86/kernel/cpu/mtrr/generic.c | 128 +++++++++++++++++++++++++++++------
1 files changed, 106 insertions(+), 22 deletions(-)
diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c
index 7d28d7d..9f27228 100644
--- a/arch/x86/kernel/cpu/mtrr/generic.c
+++ b/arch/x86/kernel/cpu/mtrr/generic.c
@@ -64,18 +64,59 @@ static inline void k8_check_syscfg_dram_mod_en(void)
}
}
+/* Get the size of contiguous MTRR range */
+static u64 get_mtrr_size(u64 mask)
+{
+ u64 size;
+
+ mask >>= PAGE_SHIFT;
+ mask |= size_or_mask;
+ size = -mask;
+ size <<= PAGE_SHIFT;
+ return size;
+}
+
/*
- * Returns the effective MTRR type for the region
- * Error returns:
- * - 0xFE - when the range is "not entirely covered" by _any_ var range MTRR
- * - 0xFF - when MTRR is not enabled
+ * Check and return the effective type for MTRR-MTRR type overlap.
+ * Returns 1 if the effective type is UNCACHEABLE, else returns 0
*/
-u8 mtrr_type_lookup(u64 start, u64 end)
+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;
+}
+
+/*
+ * Error/Semi-error returns:
+ * 0xFF - when MTRR is not enabled
+ * *repeat == 1 implies [start:end] spanned across MTRR range and type returned
+ * corresponds only to [start:*partial_end].
+ * Caller has to lookup again for [*partial_end:end].
+ */
+static u8 __mtrr_type_lookup(u64 start, u64 end, u64 *partial_end, int *repeat)
{
int i;
u64 base, mask;
u8 prev_match, curr_match;
+ *repeat = 0;
if (!mtrr_state_set)
return 0xFF;
@@ -126,8 +167,34 @@ u8 mtrr_type_lookup(u64 start, u64 end)
start_state = ((start & mask) == (base & mask));
end_state = ((end & mask) == (base & mask));
- if (start_state != end_state)
- return 0xFE;
+
+ if (start_state != end_state) {
+ /*
+ * 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)
+ * 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.
+ * Note: This way we handle multiple overlaps as well.
+ */
+ if (start_state)
+ *partial_end = base + get_mtrr_size(mask);
+ else
+ *partial_end = base;
+
+ if (unlikely(*partial_end <= start)) {
+ WARN_ON(1);
+ *partial_end = start + PAGE_SIZE;
+ }
+
+ end = *partial_end - 1; /* end is inclusive */
+ *repeat = 1;
+ }
if ((start & mask) != (base & mask))
continue;
@@ -138,21 +205,8 @@ 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) {
@@ -166,6 +220,36 @@ u8 mtrr_type_lookup(u64 start, u64 end)
return mtrr_state.def_type;
}
+/*
+ * Returns the effective MTRR type for the region
+ * Error return:
+ * 0xFF - when MTRR is not enabled
+ */
+u8 mtrr_type_lookup(u64 start, u64 end)
+{
+ u8 type, prev_type;
+ int repeat;
+ u64 partial_end;
+
+ type = __mtrr_type_lookup(start, end, &partial_end, &repeat);
+
+ /*
+ * Common path is with repeat = 0.
+ * However, we can have cases where [start:end] spans across some
+ * MTRR range. Do repeated lookups for that case here.
+ */
+ while (repeat) {
+ prev_type = type;
+ start = partial_end;
+ type = __mtrr_type_lookup(start, end, &partial_end, &repeat);
+
+ if (check_type_overlap(&prev_type, &type))
+ return type;
+ }
+
+ return type;
+}
+
/* Get the MSR pair relating to a var range */
static void
get_mtrr_var_range(unsigned int index, struct mtrr_var_range *vr)
--
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