Commit-ID: b73522e0c1be58d3c69b124985b8ccf94e3677f7 Gitweb: http://git.kernel.org/tip/b73522e0c1be58d3c69b124985b8ccf94e3677f7 Author: Toshi Kani <toshi.kani@xxxxxx> AuthorDate: Tue, 26 May 2015 10:28:10 +0200 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitDate: Wed, 27 May 2015 14:40:58 +0200 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 <toshi.kani@xxxxxx> [ Realign, flesh out comments, improve warning message. ] Signed-off-by: Borislav Petkov <bp@xxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Brian Gerst <brgerst@xxxxxxxxx> Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx> Cc: Elliott@xxxxxx Cc: H. Peter Anvin <hpa@xxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Luis R. Rodriguez <mcgrof@xxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: dave.hansen@xxxxxxxxx Cc: linux-mm <linux-mm@xxxxxxxxx> Cc: pebolle@xxxxxxxxxx Link: http://lkml.kernel.org/r/1431714237-880-7-git-send-email-toshi.kani@xxxxxx Link: http://lkml.kernel.org/r/1432628901-18044-8-git-send-email-bp@xxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> --- arch/x86/include/asm/mtrr.h | 4 ++-- arch/x86/kernel/cpu/mtrr/generic.c | 40 ++++++++++++++++++++++++++++---------- arch/x86/mm/pat.c | 4 ++-- arch/x86/mm/pgtable.c | 38 +++++++++++++++++++++++------------- 4 files changed, 58 insertions(+), 28 deletions(-) diff --git a/arch/x86/include/asm/mtrr.h b/arch/x86/include/asm/mtrr.h index bb03a54..a31759e 100644 --- a/arch/x86/include/asm/mtrr.h +++ b/arch/x86/include/asm/mtrr.h @@ -31,7 +31,7 @@ * arch_phys_wc_add and arch_phys_wc_del. */ # ifdef CONFIG_MTRR -extern u8 mtrr_type_lookup(u64 addr, u64 end); +extern u8 mtrr_type_lookup(u64 addr, u64 end, u8 *uniform); extern void mtrr_save_fixed_ranges(void *); extern void mtrr_save_state(void); extern int mtrr_add(unsigned long base, unsigned long size, @@ -50,7 +50,7 @@ extern int mtrr_trim_uncached_memory(unsigned long end_pfn); extern int amd_special_default_mtrr(void); extern int phys_wc_to_mtrr_index(int handle); # else -static inline u8 mtrr_type_lookup(u64 addr, u64 end) +static inline u8 mtrr_type_lookup(u64 addr, u64 end, u8 *uniform) { /* * Return no-MTRRs: diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c index e51100c..f782d9b 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; } diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c index 35af677..372ad42 100644 --- a/arch/x86/mm/pat.c +++ b/arch/x86/mm/pat.c @@ -267,9 +267,9 @@ static unsigned long pat_x_mtrr_type(u64 start, u64 end, * request is for WB. */ if (req_type == _PAGE_CACHE_MODE_WB) { - u8 mtrr_type; + u8 mtrr_type, uniform; - mtrr_type = mtrr_type_lookup(start, end); + mtrr_type = mtrr_type_lookup(start, end, &uniform); if (mtrr_type != MTRR_TYPE_WRBACK) return _PAGE_CACHE_MODE_UC_MINUS; diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c index c30f981..fb0a9dd 100644 --- a/arch/x86/mm/pgtable.c +++ b/arch/x86/mm/pgtable.c @@ -566,19 +566,28 @@ void native_set_fixmap(enum fixed_addresses idx, phys_addr_t phys, /** * pud_set_huge - setup kernel PUD mapping * - * MTRR can override PAT memory types with 4KiB granularity. Therefore, - * this function does not set up a huge page when the range is covered - * by a non-WB type of MTRR. MTRR_TYPE_INVALID indicates that MTRR are - * disabled. + * MTRRs can override PAT memory types with 4KiB granularity. Therefore, this + * function sets up a huge page only if any of the following conditions are met: + * + * - MTRRs are disabled, or + * + * - MTRRs are enabled and the range is completely covered by a single MTRR, or + * + * - MTRRs are enabled and the corresponding MTRR memory type is WB, which + * has no effect on the requested PAT memory type. + * + * Callers should try to decrease page size (1GB -> 2MB -> 4K) if the bigger + * page mapping attempt fails. * * Returns 1 on success and 0 on failure. */ int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot) { - u8 mtrr; + u8 mtrr, uniform; - mtrr = mtrr_type_lookup(addr, addr + PUD_SIZE); - if ((mtrr != MTRR_TYPE_WRBACK) && (mtrr != MTRR_TYPE_INVALID)) + mtrr = mtrr_type_lookup(addr, addr + PUD_SIZE, &uniform); + if ((mtrr != MTRR_TYPE_INVALID) && (!uniform) && + (mtrr != MTRR_TYPE_WRBACK)) return 0; prot = pgprot_4k_2_large(prot); @@ -593,20 +602,21 @@ int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot) /** * pmd_set_huge - setup kernel PMD mapping * - * MTRR can override PAT memory types with 4KiB granularity. Therefore, - * this function does not set up a huge page when the range is covered - * by a non-WB type of MTRR. MTRR_TYPE_INVALID indicates that MTRR are - * disabled. + * See text over pud_set_huge() above. * * Returns 1 on success and 0 on failure. */ int pmd_set_huge(pmd_t *pmd, phys_addr_t addr, pgprot_t prot) { - u8 mtrr; + u8 mtrr, uniform; - mtrr = mtrr_type_lookup(addr, addr + PMD_SIZE); - if ((mtrr != MTRR_TYPE_WRBACK) && (mtrr != MTRR_TYPE_INVALID)) + mtrr = mtrr_type_lookup(addr, addr + PMD_SIZE, &uniform); + if ((mtrr != MTRR_TYPE_INVALID) && (!uniform) && + (mtrr != MTRR_TYPE_WRBACK)) { + pr_warn_once("%s: Cannot satisfy [mem %#010llx-%#010llx] with a huge-page mapping due to MTRR override.\n", + __func__, addr, addr + PMD_SIZE); return 0; + } prot = pgprot_4k_2_large(prot); -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . 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