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authorToshi Kani <toshi.kani@hp.com>2015-04-14 15:47:32 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-04-14 16:49:04 -0700
commit6b6378355b925050eb6fa966742d8c2d65ff0d83 (patch)
tree34fae2afb71d981d8ef8a2c640836c46781c00b8 /lib/ioremap.c
parent5d72b4fba40ef4b3f7a1a11d6aacc85d9af81561 (diff)
downloadlinux-6b6378355b925050eb6fa966742d8c2d65ff0d83.tar.gz
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 <toshi.kani@hp.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Robert Elliott <Elliott@hp.com> Signed-off-by: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib/ioremap.c')
-rw-r--r--lib/ioremap.c6
1 files changed, 3 insertions, 3 deletions
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 <asm/pgtable.h>
#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)
{