From 6b6378355b925050eb6fa966742d8c2d65ff0d83 Mon Sep 17 00:00:00 2001 From: Toshi Kani Date: Tue, 14 Apr 2015 15:47:32 -0700 Subject: [PATCH] x86, mm: support huge KVA mappings on x86 Implement huge KVA mapping interfaces on x86. On x86, MTRRs can override PAT memory types with a 4KB granularity. When using a huge page, MTRRs can override the memory type of the huge page, which may lead a performance penalty. The processor can also behave in an undefined manner if a huge page is mapped to a memory range that MTRRs have mapped with multiple different memory types. Therefore, the mapping code falls back to use a smaller page size toward 4KB when a mapping range is covered by non-WB type of MTRRs. The WB type of MTRRs has no affect on the PAT memory types. pud_set_huge() and pmd_set_huge() call mtrr_type_lookup() to see if a given range is covered by MTRRs. MTRR_TYPE_WRBACK indicates that the range is either covered by WB or not covered and the MTRR default value is set to WB. 0xFF indicates that MTRRs are disabled. HAVE_ARCH_HUGE_VMAP is selected when X86_64 or X86_32 with X86_PAE is set. X86_32 without X86_PAE is not supported since such config can unlikey be benefited from this feature, and there was an issue found in testing. [fengguang.wu@intel.com: ioremap_pud_capable can be static] Signed-off-by: Toshi Kani Cc: "H. Peter Anvin" Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Arnd Bergmann Cc: Dave Hansen Cc: Robert Elliott Signed-off-by: Fengguang Wu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/x86/Kconfig | 1 + arch/x86/mm/pgtable.c | 65 +++++++++++++++++++++++++++++++++++++++++++ lib/ioremap.c | 6 ++-- 3 files changed, 69 insertions(+), 3 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 3e3aaad23414..0f948cefaeb1 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -99,6 +99,7 @@ config X86 select IRQ_FORCED_THREADING select HAVE_BPF_JIT if X86_64 select HAVE_ARCH_TRANSPARENT_HUGEPAGE + select HAVE_ARCH_HUGE_VMAP if X86_64 || (X86_32 && X86_PAE) select ARCH_HAS_SG_CHAIN select CLKEVT_I8253 select ARCH_HAVE_NMI_SAFE_CMPXCHG diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c index b28edfecbdfe..0b97d2c75df3 100644 --- a/arch/x86/mm/pgtable.c +++ b/arch/x86/mm/pgtable.c @@ -4,6 +4,7 @@ #include #include #include +#include #define PGALLOC_GFP GFP_KERNEL | __GFP_NOTRACK | __GFP_REPEAT | __GFP_ZERO @@ -560,3 +561,67 @@ void native_set_fixmap(enum fixed_addresses idx, phys_addr_t phys, { __native_set_fixmap(idx, pfn_pte(phys >> PAGE_SHIFT, flags)); } + +#ifdef CONFIG_HAVE_ARCH_HUGE_VMAP +int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot) +{ + u8 mtrr; + + /* + * Do not use a huge page when the range is covered by non-WB type + * of MTRRs. + */ + mtrr = mtrr_type_lookup(addr, addr + PUD_SIZE); + if ((mtrr != MTRR_TYPE_WRBACK) && (mtrr != 0xFF)) + return 0; + + prot = pgprot_4k_2_large(prot); + + set_pte((pte_t *)pud, pfn_pte( + (u64)addr >> PAGE_SHIFT, + __pgprot(pgprot_val(prot) | _PAGE_PSE))); + + return 1; +} + +int pmd_set_huge(pmd_t *pmd, phys_addr_t addr, pgprot_t prot) +{ + u8 mtrr; + + /* + * Do not use a huge page when the range is covered by non-WB type + * of MTRRs. + */ + mtrr = mtrr_type_lookup(addr, addr + PMD_SIZE); + if ((mtrr != MTRR_TYPE_WRBACK) && (mtrr != 0xFF)) + return 0; + + prot = pgprot_4k_2_large(prot); + + set_pte((pte_t *)pmd, pfn_pte( + (u64)addr >> PAGE_SHIFT, + __pgprot(pgprot_val(prot) | _PAGE_PSE))); + + return 1; +} + +int pud_clear_huge(pud_t *pud) +{ + if (pud_large(*pud)) { + pud_clear(pud); + return 1; + } + + return 0; +} + +int pmd_clear_huge(pmd_t *pmd) +{ + if (pmd_large(*pmd)) { + pmd_clear(pmd); + return 1; + } + + return 0; +} +#endif /* CONFIG_HAVE_ARCH_HUGE_VMAP */ diff --git a/lib/ioremap.c b/lib/ioremap.c index be249062ba6e..86c8911b0e3a 100644 --- a/lib/ioremap.c +++ b/lib/ioremap.c @@ -14,9 +14,9 @@ #include #ifdef CONFIG_HAVE_ARCH_HUGE_VMAP -int __read_mostly ioremap_pud_capable; -int __read_mostly ioremap_pmd_capable; -int __read_mostly ioremap_huge_disabled; +static int __read_mostly ioremap_pud_capable; +static int __read_mostly ioremap_pmd_capable; +static int __read_mostly ioremap_huge_disabled; static int __init set_nohugeiomap(char *str) { -- 2.34.1