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Subject[PATCH v2] powerpc/hugetlb: Fix 8M hugepages on 8xx
With HW assistance all page tables must be 4k aligned, the 8xx
drops the last 12 bits during the walk.

Redefine HUGEPD_SHIFT_MASK to mask last 12 bits out.
HUGEPD_SHIFT_MASK is used to for alignment of page table cache.

Fixes: 22569b881d37 ("powerpc/8xx: Enable 8M hugepage support with HW assistance")
Signed-off-by: Christophe Leroy <>
v2: Only do the fix of alignment which is the only vital fix.
arch/powerpc/include/asm/page.h | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h
index 86332080399a..080a0bf8e54b 100644
--- a/arch/powerpc/include/asm/page.h
+++ b/arch/powerpc/include/asm/page.h
@@ -295,8 +295,13 @@ static inline bool pfn_valid(unsigned long pfn)
* Some number of bits at the level of the page table that points to
* a hugepte are used to encode the size. This masks those bits.
+ * On 8xx, HW assistance requires 4k alignment for the hugepte.
+#ifdef CONFIG_PPC_8xx
+#define HUGEPD_SHIFT_MASK 0xfff
#define HUGEPD_SHIFT_MASK 0x3f

#ifndef __ASSEMBLY__

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