powerpc/8xx: Enable 512k hugepage support with HW assistance

For using 512k pages with hardware assistance, the PTEs have to be spread
every 128 bytes in the L2 table.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/hugetlb.h

@@ -74,7 +74,9 @@ static inline pte_t *hugepte_offset(hugepd_t hpd, unsigned long addr,
 	unsigned long idx = 0;
 
 	pte_t *dir = hugepd_page(hpd);
-#ifndef CONFIG_PPC_FSL_BOOK3E
+#ifdef CONFIG_PPC_8xx
+	idx = (addr & ((1UL << pdshift) - 1)) >> PAGE_SHIFT;
+#elif !defined(CONFIG_PPC_FSL_BOOK3E)
 	idx = (addr & ((1UL << pdshift) - 1)) >> hugepd_shift(hpd);
 #endif
 

arch/powerpc/mm/hugetlbpage.c

@@ -65,6 +65,9 @@ static int __hugepte_alloc(struct mm_struct *mm, hugepd_t *hpdp,
 	if (pshift >= pdshift) {
 		cachep = PGT_CACHE(PTE_T_ORDER);
 		num_hugepd = 1 << (pshift - pdshift);
+	} else if (IS_ENABLED(CONFIG_PPC_8xx)) {
+		cachep = PGT_CACHE(PTE_INDEX_SIZE);
+		num_hugepd = 1;
 	} else {
 		cachep = PGT_CACHE(pdshift - pshift);
 		num_hugepd = 1;
@@ -331,6 +334,9 @@ static void free_hugepd_range(struct mmu_gather *tlb, hugepd_t *hpdp, int pdshif
 
 	if (shift >= pdshift)
 		hugepd_free(tlb, hugepte);
+	else if (IS_ENABLED(CONFIG_PPC_8xx))
+		pgtable_free_tlb(tlb, hugepte,
+				 get_hugepd_cache_index(PTE_INDEX_SIZE));
 	else
 		pgtable_free_tlb(tlb, hugepte,
 				 get_hugepd_cache_index(pdshift - shift));
@@ -700,7 +706,9 @@ static int __init hugetlbpage_init(void)
 		 * if we have pdshift and shift value same, we don't
 		 * use pgt cache for hugepd.
 		 */
-		if (pdshift > shift)
+		if (pdshift > shift && IS_ENABLED(CONFIG_PPC_8xx))
+			pgtable_cache_add(PTE_INDEX_SIZE);
+		else if (pdshift > shift)
 			pgtable_cache_add(pdshift - shift);
 #if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_8xx)
 		else

arch/powerpc/mm/tlb_nohash.c

@@ -97,6 +97,9 @@ struct mmu_psize_def mmu_psize_defs[MMU_PAGE_COUNT] = {
 		.shift	= 14,
 	},
 #endif
+	[MMU_PAGE_512K] = {
+		.shift	= 19,
+	},
 	[MMU_PAGE_8M] = {
 		.shift	= 23,
 	},