diff options
Diffstat (limited to 'src/cpu')
| -rw-r--r-- | src/cpu/x86/mtrr/mtrr.c | 132 |
1 files changed, 98 insertions, 34 deletions
diff --git a/src/cpu/x86/mtrr/mtrr.c b/src/cpu/x86/mtrr/mtrr.c index 08312fbebf..7b1b659097 100644 --- a/src/cpu/x86/mtrr/mtrr.c +++ b/src/cpu/x86/mtrr/mtrr.c @@ -129,8 +129,6 @@ static void enable_var_mtrr(unsigned char deftype) #define RANGE_TO_PHYS_ADDR(x) (((resource_t)(x)) << RANGE_SHIFT) #define NUM_FIXED_MTRRS (NUM_FIXED_RANGES / RANGES_PER_FIXED_MTRR) -/* The minimum alignment while handling variable MTRR ranges is 64MiB. */ -#define MTRR_MIN_ALIGN PHYS_TO_RANGE_ADDR(64 << 20) /* Helpful constants. */ #define RANGE_1MB PHYS_TO_RANGE_ADDR(1 << 20) #define RANGE_4GB (1 << (ADDR_SHIFT_TO_RANGE_SHIFT(32))) @@ -499,22 +497,79 @@ static void calc_var_mtrr_range(struct var_mtrr_state *var_state, } } +static uint32_t optimize_var_mtrr_hole(const uint32_t base, + const uint32_t hole, + const uint64_t limit, + const int carve_hole) +{ + /* + * With default type UC, we can potentially optimize a WB + * range with unaligned upper end, by aligning it up and + * carving the added "hole" out again. + * + * To optimize the upper end of the hole, we will test + * how many MTRRs calc_var_mtrr_range() will spend for any + * alignment of the hole's upper end. + * + * We take four parameters, the lower end of the WB range + * `base`, upper end of the WB range as start of the `hole`, + * a `limit` how far we may align the upper end of the hole + * up and a flag `carve_hole` whether we should count MTRRs + * for carving the hole out. We return the optimal upper end + * for the hole (which may be the same as the end of the WB + * range in case we don't gain anything by aligning up). + */ + + const int dont_care = 0; + struct var_mtrr_state var_state = { 0, }; + + unsigned int align, best_count; + uint32_t best_end = hole; + + /* calculate MTRR count for the WB range alone (w/o a hole) */ + calc_var_mtrr_range(&var_state, base, hole - base, dont_care); + best_count = var_state.mtrr_index; + var_state.mtrr_index = 0; + + for (align = fls(hole) + 1; align <= fms(hole); ++align) { + const uint64_t hole_end = ALIGN_UP((uint64_t)hole, 1 << align); + if (hole_end > limit) + break; + + /* calculate MTRR count for this alignment */ + calc_var_mtrr_range( + &var_state, base, hole_end - base, dont_care); + if (carve_hole) + calc_var_mtrr_range( + &var_state, hole, hole_end - hole, dont_care); + + if (var_state.mtrr_index < best_count) { + best_count = var_state.mtrr_index; + best_end = hole_end; + } + var_state.mtrr_index = 0; + } + + return best_end; +} + static void calc_var_mtrrs_with_hole(struct var_mtrr_state *var_state, struct range_entry *r) { uint32_t a1, a2, b1, b2; - int mtrr_type; + uint64_t b2_limit; + int mtrr_type, carve_hole; struct range_entry *next; /* * Determine MTRRs based on the following algorithm for the given entry: * +------------------+ b2 = ALIGN_UP(end) * | 0 or more bytes | <-- hole is carved out between b1 and b2 - * +------------------+ a2 = b1 = end + * +------------------+ a2 = b1 = original end * | | * +------------------+ a1 = begin * - * Thus, there are 3 sub-ranges to configure variable MTRRs for. + * Thus, there are up to 2 sub-ranges to configure variable MTRRs for. */ mtrr_type = range_entry_mtrr_type(r); @@ -541,40 +596,49 @@ static void calc_var_mtrrs_with_hole(struct var_mtrr_state *var_state, if (!var_state->above4gb && a2 > RANGE_4GB) a2 = RANGE_4GB; - next = memranges_next_entry(var_state->addr_space, r); - b1 = a2; - /* First check if a1 is >= 4GiB and the current entry is the last - * entry. If so perform an optimization of covering a larger range - * defined by the base address' alignment. */ - if (a1 >= RANGE_4GB && next == NULL) { - uint32_t addr_lsb; - - addr_lsb = fls(a1); - b2 = (1 << addr_lsb) + a1; - if (b2 >= a2) { - calc_var_mtrr_range(var_state, a1, b2 - a1, mtrr_type); - return; - } - } - - /* Handle the min alignment roundup case. */ - b2 = ALIGN_UP(a2, MTRR_MIN_ALIGN); - - /* Check against the next range. If the current range_entry is the - * last entry then carving a hole is no problem. If the current entry - * isn't the last entry then check that the last entry covers the - * entire hole range with the default mtrr type. */ - if (next != NULL && - (range_entry_mtrr_type(next) != var_state->def_mtrr_type || - range_entry_end_mtrr_addr(next) < b2)) { - calc_var_mtrr_range(var_state, a1, a2 - a1, mtrr_type); - return; + /* + * Depending on the type of the next range, there are three + * different situations to handle: + * + * 1. WB range is last in address space: + * Aligning up, up to the next power of 2, may gain us + * something. + * + * 2. The next range is of type UC: + * We may align up, up to the _end_ of the next range. If + * there is a gap between the current and the next range, + * it would have been covered by the default type UC anyway. + * + * 3. The next range is not of type UC: + * We may align up, up to the _base_ of the next range. This + * may either be the end of the current range (if the next + * range follows immediately) or the end of the gap between + * the ranges. + */ + next = memranges_next_entry(var_state->addr_space, r); + if (next == NULL) { + b2_limit = ALIGN_UP((uint64_t)b1, 1 << fms(b1)); + /* If it's the last range above 4GiB, we won't carve + the hole out. If an OS wanted to move MMIO there, + it would have to override the MTRR setting using + PAT just like it would with WB as default type. */ + carve_hole = a1 < RANGE_4GB; + } else if (range_entry_mtrr_type(next) == MTRR_TYPE_UNCACHEABLE) { + b2_limit = range_entry_end_mtrr_addr(next); + carve_hole = 1; + } else { + b2_limit = range_entry_base_mtrr_addr(next); + carve_hole = 1; } + b2 = optimize_var_mtrr_hole(a1, b1, b2_limit, carve_hole); calc_var_mtrr_range(var_state, a1, b2 - a1, mtrr_type); - calc_var_mtrr_range(var_state, b1, b2 - b1, var_state->def_mtrr_type); + if (carve_hole && b2 != b1) { + calc_var_mtrr_range(var_state, b1, b2 - b1, + MTRR_TYPE_UNCACHEABLE); + } } static void calc_var_mtrrs_without_hole(struct var_mtrr_state *var_state, |