From 6b6378355b925050eb6fa966742d8c2d65ff0d83 Mon Sep 17 00:00:00 2001 From: Toshi Kani Date: Tue, 14 Apr 2015 15:47:32 -0700 Subject: 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 --- lib/ioremap.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'lib/ioremap.c') diff --git a/lib/ioremap.c b/lib/ioremap.c index be24906..86c8911 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) { -- cgit v1.1