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Merge branch 'x86-mtrr-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

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* 'x86-mtrr-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, mtrr: Support mtrr lookup for range spanning across MTRR range
  x86, mtrr: Refactor MTRR type overlap check code
This commit is contained in:
Linus Torvalds 2010-10-21 13:51:41 -07:00
commit d77bdc423d
1 changed files with 106 additions and 22 deletions
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128
arch/x86/kernel/cpu/mtrr/generic.c
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@ -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)