From cd2f6a5a4704a359635eb34919317052e6a96ba7 Mon Sep 17 00:00:00 2001 From: Toshi Kani Date: Mon, 11 May 2015 10:15:52 +0200 Subject: x86/mm/mtrr: Remove incorrect address check in __mtrr_type_lookup() __mtrr_type_lookup() checks MTRR fixed ranges when mtrr_state.have_fixed is set and start is less than 0x100000. However, the 'else if (start < 0x1000000)' in the code checks with an incorrect address as it has an extra-zero in the address. The code still runs correctly as this check is meaningless, though. This patch replaces the incorrect address check with 'else' with no condition. Signed-off-by: Toshi Kani Signed-off-by: Borislav Petkov Cc: Andrew Morton Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: Elliott@hp.com Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Luis R. Rodriguez Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: dave.hansen@intel.com Cc: linux-mm Cc: pebolle@tiscali.nl Link: http://lkml.kernel.org/r/1427234921-19737-4-git-send-email-toshi.kani@hp.com Link: http://lkml.kernel.org/r/1431332153-18566-8-git-send-email-bp@alien8.de Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/mtrr/generic.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/x86/kernel/cpu/mtrr/generic.c') diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c index 7d74f7b3c6ba..5b239679cfc9 100644 --- a/arch/x86/kernel/cpu/mtrr/generic.c +++ b/arch/x86/kernel/cpu/mtrr/generic.c @@ -137,7 +137,7 @@ static u8 __mtrr_type_lookup(u64 start, u64 end, u64 *partial_end, int *repeat) idx = 1 * 8; idx += ((start - 0x80000) >> 14); return mtrr_state.fixed_ranges[idx]; - } else if (start < 0x1000000) { + } else { idx = 3 * 8; idx += ((start - 0xC0000) >> 12); return mtrr_state.fixed_ranges[idx]; -- cgit v1.2.3 From 7f0431e3dc8953f41e9433581c1fdd7ee45860b0 Mon Sep 17 00:00:00 2001 From: Toshi Kani Date: Tue, 26 May 2015 10:28:05 +0200 Subject: x86/mm/mtrr: Fix MTRR lookup to handle an 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: range_start ... [mtrr_start ... mtrr_end] ... range_end __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 end_state:1 since the first region is the same. With this fix, __mtrr_type_lookup() handles the inclusive case properly. Signed-off-by: Toshi Kani Signed-off-by: Borislav Petkov Cc: Andrew Morton Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: Elliott@hp.com Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Luis R. Rodriguez Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: dave.hansen@intel.com Cc: linux-mm Cc: pebolle@tiscali.nl Link: http://lkml.kernel.org/r/1431714237-880-3-git-send-email-toshi.kani@hp.com Link: http://lkml.kernel.org/r/1432628901-18044-3-git-send-email-bp@alien8.de Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/mtrr/generic.c | 28 ++++++++++++++++++---------- 1 file changed, 18 insertions(+), 10 deletions(-) (limited to 'arch/x86/kernel/cpu/mtrr/generic.c') diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c index 5b239679cfc9..e202d26f64a2 100644 --- a/arch/x86/kernel/cpu/mtrr/generic.c +++ b/arch/x86/kernel/cpu/mtrr/generic.c @@ -154,7 +154,7 @@ static u8 __mtrr_type_lookup(u64 start, u64 end, u64 *partial_end, int *repeat) 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; @@ -166,19 +166,27 @@ static u8 __mtrr_type_lookup(u64 start, u64 end, u64 *partial_end, int *repeat) 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 + * (start:mtrr_start)(mtrr_start:end) + * - inclusive:1 + * (start:mtrr_start)(mtrr_start:mtrr_end)(mtrr_end: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. + * + * Return the type of the first region and a pointer + * to the start of next region so that caller will be + * advised to lookup again after having adjusted start + * and end. + * * Note: This way we handle multiple overlaps as well. */ if (start_state) -- cgit v1.2.3 From 9b3aca620883fc06636737c82a4d024b22182281 Mon Sep 17 00:00:00 2001 From: Toshi Kani Date: Tue, 26 May 2015 10:28:06 +0200 Subject: x86/mm/mtrr: Fix MTRR state checks in mtrr_type_lookup() 'mtrr_state.enabled' contains the FE (fixed MTRRs enabled) and E (MTRRs enabled) flags in MSR_MTRRdefType. Intel SDM, section 11.11.2.1, defines these flags as follows: - All MTRRs are disabled when the E flag is clear. The FE flag has no affect when the E flag is clear. - The default type is enabled when the E flag is set. - MTRR variable ranges are enabled when the E flag is set. - MTRR fixed ranges are enabled when both E and FE flags are set. MTRR state checks in __mtrr_type_lookup() do not match with SDM. Hence, this patch makes the following changes: - The current code detects MTRRs disabled when both E and FE flags are clear in mtrr_state.enabled. Fix to detect MTRRs disabled when the E flag is clear. - The current code does not check if the FE bit is set in mtrr_state.enabled when looking at the fixed entries. Fix to check the FE flag. - The current code returns the default type when the E flag is clear in mtrr_state.enabled. However, the default type is UC when the E flag is clear. Remove the code as this case is handled as MTRR disabled with the 1st change. In addition, this patch defines the E and FE flags in mtrr_state.enabled as follows. - FE flag: MTRR_STATE_MTRR_FIXED_ENABLED - E flag: MTRR_STATE_MTRR_ENABLED print_mtrr_state() and x86_get_mtrr_mem_range() are also updated accordingly. Signed-off-by: Toshi Kani Signed-off-by: Borislav Petkov Cc: Andrew Morton Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: Elliott@hp.com Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Luis R. Rodriguez Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: dave.hansen@intel.com Cc: linux-mm Cc: pebolle@tiscali.nl Link: http://lkml.kernel.org/r/1431714237-880-4-git-send-email-toshi.kani@hp.com Link: http://lkml.kernel.org/r/1432628901-18044-4-git-send-email-bp@alien8.de Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/mtrr/generic.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) (limited to 'arch/x86/kernel/cpu/mtrr/generic.c') diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c index e202d26f64a2..b0599dbb899a 100644 --- a/arch/x86/kernel/cpu/mtrr/generic.c +++ b/arch/x86/kernel/cpu/mtrr/generic.c @@ -119,14 +119,16 @@ static u8 __mtrr_type_lookup(u64 start, u64 end, u64 *partial_end, int *repeat) if (!mtrr_state_set) return 0xFF; - if (!mtrr_state.enabled) + if (!(mtrr_state.enabled & MTRR_STATE_MTRR_ENABLED)) return 0xFF; /* Make end inclusive end, instead of exclusive */ end--; /* Look in fixed ranges. Just return the type as per start */ - if (mtrr_state.have_fixed && (start < 0x100000)) { + if ((start < 0x100000) && + (mtrr_state.have_fixed) && + (mtrr_state.enabled & MTRR_STATE_MTRR_FIXED_ENABLED)) { int idx; if (start < 0x80000) { @@ -149,9 +151,6 @@ static u8 __mtrr_type_lookup(u64 start, u64 end, u64 *partial_end, int *repeat) * Look of multiple ranges matching this address and pick type * as per MTRR precedence */ - if (!(mtrr_state.enabled & 2)) - return mtrr_state.def_type; - prev_match = 0xFF; for (i = 0; i < num_var_ranges; ++i) { unsigned short start_state, end_state, inclusive; @@ -355,7 +354,9 @@ static void __init print_mtrr_state(void) mtrr_attrib_to_str(mtrr_state.def_type)); if (mtrr_state.have_fixed) { pr_debug("MTRR fixed ranges %sabled:\n", - mtrr_state.enabled & 1 ? "en" : "dis"); + ((mtrr_state.enabled & MTRR_STATE_MTRR_ENABLED) && + (mtrr_state.enabled & MTRR_STATE_MTRR_FIXED_ENABLED)) ? + "en" : "dis"); print_fixed(0x00000, 0x10000, mtrr_state.fixed_ranges + 0); for (i = 0; i < 2; ++i) print_fixed(0x80000 + i * 0x20000, 0x04000, @@ -368,7 +369,7 @@ static void __init print_mtrr_state(void) print_fixed_last(); } pr_debug("MTRR variable ranges %sabled:\n", - mtrr_state.enabled & 2 ? "en" : "dis"); + mtrr_state.enabled & MTRR_STATE_MTRR_ENABLED ? "en" : "dis"); high_width = (__ffs64(size_or_mask) - (32 - PAGE_SHIFT) + 3) / 4; for (i = 0; i < num_var_ranges; ++i) { -- cgit v1.2.3 From 3d3ca416d9b0784cfcf244eeeba1bcaf421bc64d Mon Sep 17 00:00:00 2001 From: Toshi Kani Date: Tue, 26 May 2015 10:28:07 +0200 Subject: x86/mm/mtrr: Use symbolic define as a retval for disabled MTRRs mtrr_type_lookup() returns verbatim 0xFF when MTRRs are disabled. This patch defines MTRR_TYPE_INVALID to clarify the meaning of this value, and documents its usage. Document the return values of the kernel virtual address mapping helpers pud_set_huge(), pmd_set_huge, pud_clear_huge() and pmd_clear_huge(). There is no functional change in this patch. Signed-off-by: Toshi Kani Signed-off-by: Borislav Petkov Cc: Andrew Morton Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: Elliott@hp.com Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Luis R. Rodriguez Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: dave.hansen@intel.com Cc: linux-mm Cc: pebolle@tiscali.nl Link: http://lkml.kernel.org/r/1431714237-880-5-git-send-email-toshi.kani@hp.com Link: http://lkml.kernel.org/r/1432628901-18044-5-git-send-email-bp@alien8.de Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/mtrr/generic.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) (limited to 'arch/x86/kernel/cpu/mtrr/generic.c') diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c index b0599dbb899a..7b1491c6232d 100644 --- a/arch/x86/kernel/cpu/mtrr/generic.c +++ b/arch/x86/kernel/cpu/mtrr/generic.c @@ -104,7 +104,7 @@ static int check_type_overlap(u8 *prev, u8 *curr) /* * Error/Semi-error returns: - * 0xFF - when MTRR is not enabled + * MTRR_TYPE_INVALID - 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]. @@ -117,10 +117,10 @@ static u8 __mtrr_type_lookup(u64 start, u64 end, u64 *partial_end, int *repeat) *repeat = 0; if (!mtrr_state_set) - return 0xFF; + return MTRR_TYPE_INVALID; if (!(mtrr_state.enabled & MTRR_STATE_MTRR_ENABLED)) - return 0xFF; + return MTRR_TYPE_INVALID; /* Make end inclusive end, instead of exclusive */ end--; @@ -151,7 +151,7 @@ static u8 __mtrr_type_lookup(u64 start, u64 end, u64 *partial_end, int *repeat) * Look of multiple ranges matching this address and pick type * as per MTRR precedence */ - prev_match = 0xFF; + prev_match = MTRR_TYPE_INVALID; for (i = 0; i < num_var_ranges; ++i) { unsigned short start_state, end_state, inclusive; @@ -206,7 +206,7 @@ static u8 __mtrr_type_lookup(u64 start, u64 end, u64 *partial_end, int *repeat) continue; curr_match = mtrr_state.var_ranges[i].base_lo & 0xff; - if (prev_match == 0xFF) { + if (prev_match == MTRR_TYPE_INVALID) { prev_match = curr_match; continue; } @@ -220,7 +220,7 @@ static u8 __mtrr_type_lookup(u64 start, u64 end, u64 *partial_end, int *repeat) return MTRR_TYPE_WRBACK; } - if (prev_match != 0xFF) + if (prev_match != MTRR_TYPE_INVALID) return prev_match; return mtrr_state.def_type; @@ -229,7 +229,7 @@ static u8 __mtrr_type_lookup(u64 start, u64 end, u64 *partial_end, int *repeat) /* * Returns the effective MTRR type for the region * Error return: - * 0xFF - when MTRR is not enabled + * MTRR_TYPE_INVALID - when MTRR is not enabled */ u8 mtrr_type_lookup(u64 start, u64 end) { -- cgit v1.2.3 From 0cc705f56e400764a171055f727d28a48260bb4b Mon Sep 17 00:00:00 2001 From: Toshi Kani Date: Tue, 26 May 2015 10:28:08 +0200 Subject: x86/mm/mtrr: Clean up mtrr_type_lookup() MTRRs contain fixed and variable entries. mtrr_type_lookup() may repeatedly call __mtrr_type_lookup() to handle a request that overlaps with variable entries. However, __mtrr_type_lookup() also handles the fixed entries, which do not have to be repeated. Therefore, this patch creates separate functions, mtrr_type_lookup_fixed() and mtrr_type_lookup_variable(), to handle the fixed and variable ranges respectively. The patch also updates the function headers to clarify the return values and output argument. It updates comments to clarify that the repeating is necessary to handle overlaps with the default type, since overlaps with multiple entries alone can be handled without such repeating. There is no functional change in this patch. Signed-off-by: Toshi Kani Signed-off-by: Borislav Petkov Cc: Andrew Morton Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: Elliott@hp.com Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Luis R. Rodriguez Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: dave.hansen@intel.com Cc: linux-mm Cc: pebolle@tiscali.nl Link: http://lkml.kernel.org/r/1431714237-880-6-git-send-email-toshi.kani@hp.com Link: http://lkml.kernel.org/r/1432628901-18044-6-git-send-email-bp@alien8.de Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/mtrr/generic.c | 138 +++++++++++++++++++++++-------------- 1 file changed, 86 insertions(+), 52 deletions(-) (limited to 'arch/x86/kernel/cpu/mtrr/generic.c') diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c index 7b1491c6232d..e51100c49eea 100644 --- a/arch/x86/kernel/cpu/mtrr/generic.c +++ b/arch/x86/kernel/cpu/mtrr/generic.c @@ -102,55 +102,68 @@ static int check_type_overlap(u8 *prev, u8 *curr) return 0; } -/* - * Error/Semi-error returns: - * MTRR_TYPE_INVALID - 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]. +/** + * mtrr_type_lookup_fixed - look up memory type in MTRR fixed entries + * + * Return the MTRR fixed memory type of 'start'. + * + * MTRR fixed entries are divided into the following ways: + * 0x00000 - 0x7FFFF : This range is divided into eight 64KB sub-ranges + * 0x80000 - 0xBFFFF : This range is divided into sixteen 16KB sub-ranges + * 0xC0000 - 0xFFFFF : This range is divided into sixty-four 4KB sub-ranges + * + * Return Values: + * MTRR_TYPE_(type) - Matched memory type + * MTRR_TYPE_INVALID - Unmatched + */ +static u8 mtrr_type_lookup_fixed(u64 start, u64 end) +{ + int idx; + + if (start >= 0x100000) + return MTRR_TYPE_INVALID; + + /* 0x0 - 0x7FFFF */ + if (start < 0x80000) { + idx = 0; + idx += (start >> 16); + return mtrr_state.fixed_ranges[idx]; + /* 0x80000 - 0xBFFFF */ + } else if (start < 0xC0000) { + idx = 1 * 8; + idx += ((start - 0x80000) >> 14); + return mtrr_state.fixed_ranges[idx]; + } + + /* 0xC0000 - 0xFFFFF */ + idx = 3 * 8; + idx += ((start - 0xC0000) >> 12); + return mtrr_state.fixed_ranges[idx]; +} + +/** + * mtrr_type_lookup_variable - look up memory type in MTRR variable entries + * + * Return Value: + * MTRR_TYPE_(type) - Matched memory type or default memory type (unmatched) + * + * Output Argument: + * repeat - Set to 1 when [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) +static u8 mtrr_type_lookup_variable(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 MTRR_TYPE_INVALID; - - if (!(mtrr_state.enabled & MTRR_STATE_MTRR_ENABLED)) - return MTRR_TYPE_INVALID; - /* Make end inclusive end, instead of exclusive */ + /* Make end inclusive instead of exclusive */ end--; - /* Look in fixed ranges. Just return the type as per start */ - if ((start < 0x100000) && - (mtrr_state.have_fixed) && - (mtrr_state.enabled & MTRR_STATE_MTRR_FIXED_ENABLED)) { - int idx; - - if (start < 0x80000) { - idx = 0; - idx += (start >> 16); - return mtrr_state.fixed_ranges[idx]; - } else if (start < 0xC0000) { - idx = 1 * 8; - idx += ((start - 0x80000) >> 14); - return mtrr_state.fixed_ranges[idx]; - } else { - idx = 3 * 8; - idx += ((start - 0xC0000) >> 12); - return mtrr_state.fixed_ranges[idx]; - } - } - - /* - * Look in variable ranges - * Look of multiple ranges matching this address and pick type - * as per MTRR precedence - */ prev_match = MTRR_TYPE_INVALID; for (i = 0; i < num_var_ranges; ++i) { unsigned short start_state, end_state, inclusive; @@ -186,7 +199,8 @@ static u8 __mtrr_type_lookup(u64 start, u64 end, u64 *partial_end, int *repeat) * advised to lookup again after having adjusted start * and end. * - * Note: This way we handle multiple overlaps as well. + * Note: This way we handle overlaps with multiple + * entries and the default type properly. */ if (start_state) *partial_end = base + get_mtrr_size(mask); @@ -215,21 +229,18 @@ static u8 __mtrr_type_lookup(u64 start, u64 end, u64 *partial_end, int *repeat) return curr_match; } - if (mtrr_tom2) { - if (start >= (1ULL<<32) && (end < mtrr_tom2)) - return MTRR_TYPE_WRBACK; - } - if (prev_match != MTRR_TYPE_INVALID) return prev_match; return mtrr_state.def_type; } -/* - * Returns the effective MTRR type for the region - * Error return: - * MTRR_TYPE_INVALID - when MTRR is not enabled +/** + * mtrr_type_lookup - look up memory type in MTRR + * + * Return Values: + * MTRR_TYPE_(type) - The effective MTRR type for the region + * MTRR_TYPE_INVALID - MTRR is disabled */ u8 mtrr_type_lookup(u64 start, u64 end) { @@ -237,22 +248,45 @@ u8 mtrr_type_lookup(u64 start, u64 end) int repeat; u64 partial_end; - type = __mtrr_type_lookup(start, end, &partial_end, &repeat); + if (!mtrr_state_set) + return MTRR_TYPE_INVALID; + + if (!(mtrr_state.enabled & MTRR_STATE_MTRR_ENABLED)) + return MTRR_TYPE_INVALID; + + /* + * Look up the fixed ranges first, which take priority over + * the variable ranges. + */ + if ((start < 0x100000) && + (mtrr_state.have_fixed) && + (mtrr_state.enabled & MTRR_STATE_MTRR_FIXED_ENABLED)) + return mtrr_type_lookup_fixed(start, end); + + /* + * Look up the variable ranges. Look of multiple ranges matching + * this address and pick type as per MTRR precedence. + */ + type = mtrr_type_lookup_variable(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. + * MTRR ranges and/or the default type. Do repeated lookups for + * that case here. */ while (repeat) { prev_type = type; start = partial_end; - type = __mtrr_type_lookup(start, end, &partial_end, &repeat); + type = mtrr_type_lookup_variable(start, end, &partial_end, &repeat); if (check_type_overlap(&prev_type, &type)) return type; } + if (mtrr_tom2 && (start >= (1ULL<<32)) && (end < mtrr_tom2)) + return MTRR_TYPE_WRBACK; + return type; } -- cgit v1.2.3 From b73522e0c1be58d3c69b124985b8ccf94e3677f7 Mon Sep 17 00:00:00 2001 From: Toshi Kani Date: Tue, 26 May 2015 10:28:10 +0200 Subject: x86/mm/mtrr: Enhance MTRR checks in kernel mapping helpers This patch adds the argument 'uniform' to mtrr_type_lookup(), which gets set to 1 when a given range is covered uniformly by MTRRs, i.e. the range is fully covered by a single MTRR entry or the default type. Change pud_set_huge() and pmd_set_huge() to honor the 'uniform' flag to see if it is safe to create a huge page mapping in the range. This allows them to create a huge page mapping in a range covered by a single MTRR entry of any memory type. It also detects a non-optimal request properly. They continue to check with the WB type since it does not effectively change the uniform mapping even if a request spans multiple MTRR entries. pmd_set_huge() logs a warning message to a non-optimal request so that driver writers will be aware of such a case. Drivers should make a mapping request aligned to a single MTRR entry when the range is covered by MTRRs. Signed-off-by: Toshi Kani [ Realign, flesh out comments, improve warning message. ] Signed-off-by: Borislav Petkov Cc: Andrew Morton Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: Elliott@hp.com Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Luis R. Rodriguez Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: dave.hansen@intel.com Cc: linux-mm Cc: pebolle@tiscali.nl Link: http://lkml.kernel.org/r/1431714237-880-7-git-send-email-toshi.kani@hp.com Link: http://lkml.kernel.org/r/1432628901-18044-8-git-send-email-bp@alien8.de Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/mtrr/generic.c | 40 ++++++++++++++++++++++++++++---------- 1 file changed, 30 insertions(+), 10 deletions(-) (limited to 'arch/x86/kernel/cpu/mtrr/generic.c') diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c index e51100c49eea..f782d9b62cb3 100644 --- a/arch/x86/kernel/cpu/mtrr/generic.c +++ b/arch/x86/kernel/cpu/mtrr/generic.c @@ -147,19 +147,24 @@ static u8 mtrr_type_lookup_fixed(u64 start, u64 end) * Return Value: * MTRR_TYPE_(type) - Matched memory type or default memory type (unmatched) * - * Output Argument: + * Output Arguments: * repeat - Set to 1 when [start:end] spanned across MTRR range and type * returned corresponds only to [start:*partial_end]. Caller has * to lookup again for [*partial_end:end]. + * + * uniform - Set to 1 when an MTRR covers the region uniformly, i.e. the + * region is fully covered by a single MTRR entry or the default + * type. */ static u8 mtrr_type_lookup_variable(u64 start, u64 end, u64 *partial_end, - int *repeat) + int *repeat, u8 *uniform) { int i; u64 base, mask; u8 prev_match, curr_match; *repeat = 0; + *uniform = 1; /* Make end inclusive instead of exclusive */ end--; @@ -214,6 +219,7 @@ static u8 mtrr_type_lookup_variable(u64 start, u64 end, u64 *partial_end, end = *partial_end - 1; /* end is inclusive */ *repeat = 1; + *uniform = 0; } if ((start & mask) != (base & mask)) @@ -225,6 +231,7 @@ static u8 mtrr_type_lookup_variable(u64 start, u64 end, u64 *partial_end, continue; } + *uniform = 0; if (check_type_overlap(&prev_match, &curr_match)) return curr_match; } @@ -241,10 +248,15 @@ static u8 mtrr_type_lookup_variable(u64 start, u64 end, u64 *partial_end, * Return Values: * MTRR_TYPE_(type) - The effective MTRR type for the region * MTRR_TYPE_INVALID - MTRR is disabled + * + * Output Argument: + * uniform - Set to 1 when an MTRR covers the region uniformly, i.e. the + * region is fully covered by a single MTRR entry or the default + * type. */ -u8 mtrr_type_lookup(u64 start, u64 end) +u8 mtrr_type_lookup(u64 start, u64 end, u8 *uniform) { - u8 type, prev_type; + u8 type, prev_type, is_uniform = 1, dummy; int repeat; u64 partial_end; @@ -260,14 +272,18 @@ u8 mtrr_type_lookup(u64 start, u64 end) */ if ((start < 0x100000) && (mtrr_state.have_fixed) && - (mtrr_state.enabled & MTRR_STATE_MTRR_FIXED_ENABLED)) - return mtrr_type_lookup_fixed(start, end); + (mtrr_state.enabled & MTRR_STATE_MTRR_FIXED_ENABLED)) { + is_uniform = 0; + type = mtrr_type_lookup_fixed(start, end); + goto out; + } /* * Look up the variable ranges. Look of multiple ranges matching * this address and pick type as per MTRR precedence. */ - type = mtrr_type_lookup_variable(start, end, &partial_end, &repeat); + type = mtrr_type_lookup_variable(start, end, &partial_end, + &repeat, &is_uniform); /* * Common path is with repeat = 0. @@ -278,15 +294,19 @@ u8 mtrr_type_lookup(u64 start, u64 end) while (repeat) { prev_type = type; start = partial_end; - type = mtrr_type_lookup_variable(start, end, &partial_end, &repeat); + is_uniform = 0; + type = mtrr_type_lookup_variable(start, end, &partial_end, + &repeat, &dummy); if (check_type_overlap(&prev_type, &type)) - return type; + goto out; } if (mtrr_tom2 && (start >= (1ULL<<32)) && (end < mtrr_tom2)) - return MTRR_TYPE_WRBACK; + type = MTRR_TYPE_WRBACK; +out: + *uniform = is_uniform; return type; } -- cgit v1.2.3 From f9626104a5b6815ec7d65789dfb900af5fa51e64 Mon Sep 17 00:00:00 2001 From: "Luis R. Rodriguez" Date: Tue, 26 May 2015 10:28:14 +0200 Subject: x86/mm/mtrr: Generalize runtime disabling of MTRRs MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit It is possible to enable CONFIG_MTRR and CONFIG_X86_PAT and end up with a system with MTRR functionality disabled but PAT functionality enabled. This can happen, for instance, when the Xen hypervisor is used where MTRRs are not supported but PAT is. This can happen on Linux as of commit 47591df50512 ("xen: Support Xen pv-domains using PAT") by Juergen, introduced in v3.19. Technically, we should assume the proper CPU bits would be set to disable MTRRs but we can't always rely on this. At least on the Xen Hypervisor, for instance, only X86_FEATURE_MTRR was disabled as of Xen 4.4 through Xen commit 586ab6a [0], but not X86_FEATURE_K6_MTRR, X86_FEATURE_CENTAUR_MCR, or X86_FEATURE_CYRIX_ARR for instance. Roger Pau Monné has clarified though that although this is technically true we will never support PVH on these CPU types so Xen has no need to disable these bits on those systems. As per Roger, AMD K6, Centaur and VIA chips don't have the necessary hardware extensions to allow running PVH guests [1]. As per Toshi it is also possible for the BIOS to disable MTRR support, in such cases get_mtrr_state() would update the MTRR state as per the BIOS, we need to propagate this information as well. x86 MTRR code relies on quite a bit of checks for mtrr_if being set to check to see if MTRRs did get set up. Instead, lets provide a generic getter for that. This also adds a few checks where they were not before which could potentially safeguard ourselves against incorrect usage of MTRR where this was not desirable. Where possible match error codes as if MTRRs were disabled on arch/x86/include/asm/mtrr.h. Lastly, since disabling MTRRs can happen at run time and we could end up with PAT enabled, best record now in our logs when MTRRs are disabled. [0] ~/devel/xen (git::stable-4.5)$ git describe --contains 586ab6a 4.4.0-rc1~18 [1] http://lists.xenproject.org/archives/html/xen-devel/2015-03/msg03460.html Signed-off-by: Luis R. Rodriguez Signed-off-by: Borislav Petkov Cc: Andy Lutomirski Cc: Antonino Daplas Cc: Borislav Petkov Cc: Brian Gerst Cc: Daniel Vetter Cc: Dave Airlie Cc: Dave Hansen Cc: Davidlohr Bueso Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Jean-Christophe Plagniol-Villard Cc: Juergen Gross Cc: Linus Torvalds Cc: Mel Gorman Cc: Peter Zijlstra Cc: Roger Pau Monné Cc: Stefan Bader Cc: Suresh Siddha Cc: Thomas Gleixner Cc: Tomi Valkeinen Cc: Toshi Kani Cc: Ville Syrjälä Cc: Vlastimil Babka Cc: bhelgaas@google.com Cc: david.vrabel@citrix.com Cc: jbeulich@suse.com Cc: konrad.wilk@oracle.com Cc: venkatesh.pallipadi@intel.com Cc: ville.syrjala@linux.intel.com Cc: xen-devel@lists.xensource.com Link: http://lkml.kernel.org/r/1426893517-2511-3-git-send-email-mcgrof@do-not-panic.com Link: http://lkml.kernel.org/r/1432628901-18044-12-git-send-email-bp@alien8.de Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/mtrr/generic.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'arch/x86/kernel/cpu/mtrr/generic.c') diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c index f782d9b62cb3..3b533cf37c74 100644 --- a/arch/x86/kernel/cpu/mtrr/generic.c +++ b/arch/x86/kernel/cpu/mtrr/generic.c @@ -445,7 +445,7 @@ static void __init print_mtrr_state(void) } /* Grab all of the MTRR state for this CPU into *state */ -void __init get_mtrr_state(void) +bool __init get_mtrr_state(void) { struct mtrr_var_range *vrs; unsigned long flags; @@ -489,6 +489,8 @@ void __init get_mtrr_state(void) post_set(); local_irq_restore(flags); + + return !!(mtrr_state.enabled & MTRR_STATE_MTRR_ENABLED); } /* Some BIOS's are messed up and don't set all MTRRs the same! */ -- cgit v1.2.3