powerpc: define support for 16G hugepages

The huge page size is defined for 16G pages.  If a hugepagesz of 16G is
specified at boot-time then it becomes the huge page size instead of the
default 16M.

The change in pgtable-64K.h is to the macro pte_iterate_hashed_subpages to
make the increment to va (the 1 being shifted) be a long so that it is not
shifted to 0.  Otherwise it would create an infinite loop when the shift
value is for a 16G page (when base page size is 64K).

Signed-off-by: Jon Tollefson <kniht@linux.vnet.ibm.com>
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 44 insertions, 18 deletions

diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index e2a650a9e533..19b1a9cec6d5 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -24,8 +24,9 @@
 #include <asm/cputable.h>
 #include <asm/spu.h>
 
-#define HPAGE_SHIFT_64K 16
-#define HPAGE_SHIFT_16M 24
+#define PAGE_SHIFT_64K  16
+#define PAGE_SHIFT_16M  24
+#define PAGE_SHIFT_16G  34
 
 #define NUM_LOW_AREAS   (0x100000000UL >> SID_SHIFT)
 #define NUM_HIGH_AREAS  (PGTABLE_RANGE >> HTLB_AREA_SHIFT)
@@ -95,7 +96,7 @@ static int __hugepte_alloc(struct mm_struct *mm, hugepd_t *hpdp,
 static inline
 pmd_t *hpmd_offset(pud_t *pud, unsigned long addr)
 {
-        if (HPAGE_SHIFT == HPAGE_SHIFT_64K)
+        if (HPAGE_SHIFT == PAGE_SHIFT_64K)
                 return pmd_offset(pud, addr);
         else
                 return (pmd_t *) pud;
@@ -103,7 +104,7 @@ pmd_t *hpmd_offset(pud_t *pud, unsigned long addr)
 static inline
 pmd_t *hpmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long addr)
 {
-        if (HPAGE_SHIFT == HPAGE_SHIFT_64K)
+        if (HPAGE_SHIFT == PAGE_SHIFT_64K)
                 return pmd_alloc(mm, pud, addr);
         else
                 return (pmd_t *) pud;
@@ -260,7 +261,7 @@ static void hugetlb_free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
                         continue;
                 hugetlb_free_pmd_range(tlb, pud, addr, next, floor, ceiling);
 #else
-                if (HPAGE_SHIFT == HPAGE_SHIFT_64K) {
+                if (HPAGE_SHIFT == PAGE_SHIFT_64K) {
                         if (pud_none_or_clear_bad(pud))
                                 continue;
                         hugetlb_free_pmd_range(tlb, pud, addr, next, floor, ceiling);
@@ -592,20 +593,40 @@ void set_huge_psize(int psize)
 {
         /* Check that it is a page size supported by the hardware and
          * that it fits within pagetable limits. */
-        if (mmu_psize_defs[psize].shift && mmu_psize_defs[psize].shift < SID_SHIFT &&
+        if (mmu_psize_defs[psize].shift &&
+                mmu_psize_defs[psize].shift < SID_SHIFT_1T &&
                 (mmu_psize_defs[psize].shift > MIN_HUGEPTE_SHIFT ||
-                        mmu_psize_defs[psize].shift == HPAGE_SHIFT_64K)) {
+                 mmu_psize_defs[psize].shift == PAGE_SHIFT_64K ||
+                 mmu_psize_defs[psize].shift == PAGE_SHIFT_16G)) {
+                /* Return if huge page size is the same as the
+                 * base page size. */
+                if (mmu_psize_defs[psize].shift == PAGE_SHIFT)
+                        return;
+
                 HPAGE_SHIFT = mmu_psize_defs[psize].shift;
                 mmu_huge_psize = psize;
-#ifdef CONFIG_PPC_64K_PAGES
-                hugepte_shift = (PMD_SHIFT-HPAGE_SHIFT);
-#else
-                if (HPAGE_SHIFT == HPAGE_SHIFT_64K)
-                        hugepte_shift = (PMD_SHIFT-HPAGE_SHIFT);
-                else
-                        hugepte_shift = (PUD_SHIFT-HPAGE_SHIFT);
-#endif
 
+                switch (HPAGE_SHIFT) {
+                case PAGE_SHIFT_64K:
+                    /* We only allow 64k hpages with 4k base page,
+                     * which was checked above, and always put them
+                     * at the PMD */
+                    hugepte_shift = PMD_SHIFT;
+                    break;
+                case PAGE_SHIFT_16M:
+                    /* 16M pages can be at two different levels
+                     * of pagestables based on base page size */
+                    if (PAGE_SHIFT == PAGE_SHIFT_64K)
+                            hugepte_shift = PMD_SHIFT;
+                    else /* 4k base page */
+                            hugepte_shift = PUD_SHIFT;
+                    break;
+                case PAGE_SHIFT_16G:
+                    /* 16G pages are always at PGD level */
+                    hugepte_shift = PGDIR_SHIFT;
+                    break;
+                }
+                hugepte_shift -= HPAGE_SHIFT;
         } else
                 HPAGE_SHIFT = 0;
 }
@@ -621,17 +642,22 @@ static int __init hugepage_setup_sz(char *str)
         shift = __ffs(size);
         switch (shift) {
 #ifndef CONFIG_PPC_64K_PAGES
-        case HPAGE_SHIFT_64K:
+        case PAGE_SHIFT_64K:
                 mmu_psize = MMU_PAGE_64K;
                 break;
 #endif
-        case HPAGE_SHIFT_16M:
+        case PAGE_SHIFT_16M:
                 mmu_psize = MMU_PAGE_16M;
                 break;
+        case PAGE_SHIFT_16G:
+                mmu_psize = MMU_PAGE_16G;
+                break;
         }
 
-        if (mmu_psize >=0 && mmu_psize_defs[mmu_psize].shift)
+        if (mmu_psize >= 0 && mmu_psize_defs[mmu_psize].shift) {
                 set_huge_psize(mmu_psize);
+                hugetlb_add_hstate(shift - PAGE_SHIFT);
+        }
         else
                 printk(KERN_WARNING "Invalid huge page size specified(%llu)\n", size);