From: "Aneesh Kumar K.V" <aneesh.ku...@linux.vnet.ibm.com>
We enable only if the we support 16MB page size.
Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com>
---
arch/powerpc/include/asm/pgtable.h | 30 ++++++++++++++++++++++++++++--
1 file changed, 28 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/include/asm/pgtable.h
b/arch/powerpc/include/asm/pgtable.h
index 09f3a77..17120c3 100644
--- a/arch/powerpc/include/asm/pgtable.h
+++ b/arch/powerpc/include/asm/pgtable.h
@@ -107,8 +107,34 @@ static inline int pmd_trans_huge(pmd_t pmd)
return ((pmd_val(pmd) & PMD_ISHUGE) == PMD_ISHUGE);
}
-/* We will enable it in the last patch */
-#define has_transparent_hugepage() 0
+static inline int has_transparent_hugepage(void)
+{
+ if (!mmu_has_feature(MMU_FTR_16M_PAGE))
+ return 0;
+ /*
+ * We support THP only if HPAGE_SHIFT is 16MB.
+ */
+ if (!HPAGE_SHIFT || (HPAGE_SHIFT != mmu_psize_defs[MMU_PAGE_16M].shift))
+ return 0;
+ /*
+ * We need to make sure that we support 16MB huge page 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 &&
+ ((signed int)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;
+}
static inline pmd_t pmd_mkold(pmd_t pmd)
{
--
1.7.10
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