From: "Aneesh Kumar K.V" <aneesh.ku...@linux.vnet.ibm.com>
We enable only if the we support 16MB page size.
Reviewed-by: David Gibson <d...@au1.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com>
---
arch/powerpc/include/asm/pgtable-ppc64.h | 3 +--
arch/powerpc/mm/pgtable_64.c | 29 +++++++++++++++++++++++++++++
2 files changed, 30 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/include/asm/pgtable-ppc64.h
b/arch/powerpc/include/asm/pgtable-ppc64.h
index 69cb52b..d046289 100644
--- a/arch/powerpc/include/asm/pgtable-ppc64.h
+++ b/arch/powerpc/include/asm/pgtable-ppc64.h
@@ -429,8 +429,7 @@ static inline int pmd_trans_splitting(pmd_t pmd)
return 0;
}
-/* We will enable it in the last patch */
-#define has_transparent_hugepage() 0
+extern int has_transparent_hugepage(void);
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
static inline pte_t pmd_pte(pmd_t pmd)
diff --git a/arch/powerpc/mm/pgtable_64.c b/arch/powerpc/mm/pgtable_64.c
index 2ff92aa..1abf9cd 100644
--- a/arch/powerpc/mm/pgtable_64.c
+++ b/arch/powerpc/mm/pgtable_64.c
@@ -818,4 +818,33 @@ pmd_t pmdp_get_and_clear(struct mm_struct *mm,
memset(pgtable, 0, PTE_FRAG_SIZE);
return old_pmd;
}
+
+int has_transparent_hugepage(void)
+{
+ if (!mmu_has_feature(MMU_FTR_16M_PAGE))
+ return 0;
+ /*
+ * We support THP only if PMD_SIZE is 16MB.
+ */
+ if (mmu_psize_defs[MMU_PAGE_16M].shift != PMD_SHIFT)
+ return 0;
+ /*
+ * We need to make sure that we support 16MB hugepage in a segement
+ * with base page size 64K or 4K. We only enable THP with a PAGE_SIZE
+ * of 64K.
+ */
+ /*
+ * If we have 64K HPTE, we will be using that by default
+ */
+ if (mmu_psize_defs[MMU_PAGE_64K].shift &&
+ (mmu_psize_defs[MMU_PAGE_64K].penc[MMU_PAGE_16M] == -1))
+ return 0;
+ /*
+ * Ok we only have 4K HPTE
+ */
+ if (mmu_psize_defs[MMU_PAGE_4K].penc[MMU_PAGE_16M] == -1)
+ return 0;
+
+ return 1;
+}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
--
1.8.1.2
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