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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 /arch
parent5d72b4fba40ef4b3f7a1a11d6aacc85d9af81561 (diff)
downloadlinux-6b6378355b925050eb6fa966742d8c2d65ff0d83.tar.bz2
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 'arch')
-rw-r--r--arch/x86/Kconfig1
-rw-r--r--arch/x86/mm/pgtable.c65
2 files changed, 66 insertions, 0 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 <asm/pgtable.h>
#include <asm/tlb.h>
#include <asm/fixmap.h>
+#include <asm/mtrr.h>
#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 */