diff options
| author | Toshi Kani <toshi.kani@hp.com> | 2015-04-14 15:47:32 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-04-14 16:49:04 -0700 |
| commit | 6b6378355b925050eb6fa966742d8c2d65ff0d83 (patch) | |
| tree | 34fae2afb71d981d8ef8a2c640836c46781c00b8 /lib | |
| parent | 5d72b4fba40ef4b3f7a1a11d6aacc85d9af81561 (diff) | |
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')
| -rw-r--r-- | lib/ioremap.c | 6 |
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) { |