The patch titled
Subject: x86, mm: support huge KVA mappings on x86
has been added to the -mm tree. Its filename is
x86-mm-support-huge-kva-mappings-on-x86.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/x86-mm-support-huge-kva-mappings-on-x86.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/x86-mm-support-huge-kva-mappings-on-x86.patch
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------------------------------------------------------
From: Toshi Kani <toshi.kani@xxxxxx>
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.
Signed-off-by: Toshi Kani <toshi.kani@xxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
Cc: Robert Elliott <Elliott@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/x86/Kconfig | 1
arch/x86/mm/pgtable.c | 65 ++++++++++++++++++++++++++++++++++++++++
2 files changed, 66 insertions(+)
diff -puN arch/x86/Kconfig~x86-mm-support-huge-kva-mappings-on-x86 arch/x86/Kconfig
--- a/arch/x86/Kconfig~x86-mm-support-huge-kva-mappings-on-x86
+++ a/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 -puN arch/x86/mm/pgtable.c~x86-mm-support-huge-kva-mappings-on-x86 arch/x86/mm/pgtable.c
--- a/arch/x86/mm/pgtable.c~x86-mm-support-huge-kva-mappings-on-x86
+++ a/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
@@ -485,3 +486,67 @@ void native_set_fixmap(enum fixed_addres
{
__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 */
_
Patches currently in -mm which might be from toshi.kani@xxxxxx are
mm-change-__get_vm_area_node-to-use-fls_long.patch
lib-add-huge-i-o-map-capability-interfaces.patch
mm-change-ioremap-to-set-up-huge-i-o-mappings.patch
mm-change-vunmap-to-tear-down-huge-kva-mappings.patch
x86-mm-support-huge-i-o-mapping-capability-i-f.patch
x86-mm-support-huge-kva-mappings-on-x86.patch
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