[PATCH] powerpc/mm: Disable hugepd for 64K page size.

[PATCH] powerpc/mm: Disable hugepd for 64K page size.

[Aneesh Kumar K.V]

After commit e2b3d202d1dba8f3546ed28224ce485bc50010be
("powerpc: Switch 16GB and 16MB explicit hugepages to a
different page table format"), we don't need to support
is_hugepd() for 64K page size.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/page.h | 15 +++++++++++++++
 arch/powerpc/mm/hugetlbpage.c   | 19 +++++++++++++++++++
 2 files changed, 34 insertions(+)

diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h
index 71294a6e976e..d90247b017b3 100644
--- a/arch/powerpc/include/asm/page.h
+++ b/arch/powerpc/include/asm/page.h
@@ -362,6 +362,20 @@ typedef struct { signed long pd; } hugepd_t;
 
 #ifdef CONFIG_HUGETLB_PAGE
 #ifdef CONFIG_PPC_BOOK3S_64
+#ifdef CONFIG_PPC_64K_PAGES
+/*
+ * With 64k page size, we have hugepage ptes in the pgd and pmd entries. We don't
+ * need to setup hugepage directory for them. Our pte and page directory format
+ * enable us to have this enabled. But to avoid errors when implementing new
+ * features disable hugepd for 64K. We enable a debug version here, So we catch
+ * wrong usage.
+ */
+#ifdef CONFIG_DEBUG_VM
+extern int hugepd_ok(hugepd_t hpd);
+#else
+#define hugepd_ok(x)	(0)
+#endif
+#else
 static inline int hugepd_ok(hugepd_t hpd)
 {
 	/*
@@ -370,6 +384,7 @@ static inline int hugepd_ok(hugepd_t hpd)
 	 */
 	return (((hpd.pd & 0x3) == 0x0) && ((hpd.pd & HUGEPD_SHIFT_MASK) != 0));
 }
+#endif
 #else
 static inline int hugepd_ok(hugepd_t hpd)
 {
diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index bb0bd7025cb8..8f4936e6a3db 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -89,6 +89,25 @@ int pgd_huge(pgd_t pgd)
 	 */
 	return ((pgd_val(pgd) & 0x3) != 0x0);
 }
+
+#if defined(CONFIG_PPC_64K_PAGES) && defined(CONFIG_DEBUG_VM)
+/*
+ * This enables us to catch the wrong page directory format
+ * Moved here so that we can use WARN() in the call.
+ */
+int hugepd_ok(hugepd_t hpd)
+{
+	bool is_hugepd;
+
+	/*
+	 * We should not find this format in page directory, warn otherwise.
+	 */
+	is_hugepd = (((hpd.pd & 0x3) == 0x0) && ((hpd.pd & HUGEPD_SHIFT_MASK) != 0));
+	WARN(is_hugepd, "Found wrong page directory format\n");
+	return 0;
+}
+#endif
+
 #else
 int pmd_huge(pmd_t pmd)
 {
-- 
2.5.0

Re: powerpc/mm: Disable hugepd for 64K page size.

[Michael Ellerman]

On Mon, 2015-07-09 at 07:23:53 UTC, "Aneesh Kumar K.V" wrote:
> After commit e2b3d202d1dba8f3546ed28224ce485bc50010be
> ("powerpc: Switch 16GB and 16MB explicit hugepages to a
> different page table format"), we don't need to support
> is_hugepd() for 64K page size.
> 
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/ec2640b114d535ba7d895b6e

cheers