diff options
| -rw-r--r-- | arch/x86/kernel/cpu/mtrr/generic.c | 84 |
1 files changed, 77 insertions, 7 deletions
diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c index 14f4f0c0329..9f27228ceff 100644 --- a/arch/x86/kernel/cpu/mtrr/generic.c +++ b/arch/x86/kernel/cpu/mtrr/generic.c @@ -64,6 +64,18 @@ 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; +} + /* * Check and return the effective type for MTRR-MTRR type overlap. * Returns 1 if the effective type is UNCACHEABLE, else returns 0 @@ -92,17 +104,19 @@ static int check_type_overlap(u8 *prev, u8 *curr) } /* - * 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 + * 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]. */ -u8 mtrr_type_lookup(u64 start, u64 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; @@ -153,8 +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; @@ -180,6 +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) |