[PATCH 5.5 055/150] powerpc/hugetlb: Fix 512k hugepages on 8xx with 16k page size

[Greg Kroah-Hartman]

From: Christophe Leroy <christophe.leroy@xxxxxx>

commit f2b67ef90b0d5eca0f2255e02cf2f620bc0ddcdb upstream.

Commit 55c8fc3f4930 ("powerpc/8xx: reintroduce 16K pages with HW
assistance") redefined pte_t as a struct of 4 pte_basic_t, because
in 16K pages mode there are four identical entries in the
page table. But the size of hugepage tables is calculated based
of the size of (void *). Therefore, we end up with page tables
of size 1k instead of 4k for 512k pages.

As 512k hugepage tables are the same size as standard page tables,
ie 4k, use the standard page tables instead of PGT_CACHE tables.

Fixes: 3fb69c6a1a13 ("powerpc/8xx: Enable 512k hugepage support with HW assistance")
Cc: stable@xxxxxxxxxxxxxxx # v5.0+
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/90ec56a2315be602494619ed0223bba3b0b8d619.1580997007.git.christophe.leroy@xxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/powerpc/mm/hugetlbpage.c |   29 ++++++++++++++++++-----------
 1 file changed, 18 insertions(+), 11 deletions(-)

--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -53,20 +53,24 @@ static int __hugepte_alloc(struct mm_str
 	if (pshift >= pdshift) {
 		cachep = PGT_CACHE(PTE_T_ORDER);
 		num_hugepd = 1 << (pshift - pdshift);
+		new = NULL;
 	} else if (IS_ENABLED(CONFIG_PPC_8xx)) {
-		cachep = PGT_CACHE(PTE_INDEX_SIZE);
+		cachep = NULL;
 		num_hugepd = 1;
+		new = pte_alloc_one(mm);
 	} else {
 		cachep = PGT_CACHE(pdshift - pshift);
 		num_hugepd = 1;
+		new = NULL;
 	}
 
-	if (!cachep) {
+	if (!cachep && !new) {
 		WARN_ONCE(1, "No page table cache created for hugetlb tables");
 		return -ENOMEM;
 	}
 
-	new = kmem_cache_alloc(cachep, pgtable_gfp_flags(mm, GFP_KERNEL));
+	if (cachep)
+		new = kmem_cache_alloc(cachep, pgtable_gfp_flags(mm, GFP_KERNEL));
 
 	BUG_ON(pshift > HUGEPD_SHIFT_MASK);
 	BUG_ON((unsigned long)new & HUGEPD_SHIFT_MASK);
@@ -97,7 +101,10 @@ static int __hugepte_alloc(struct mm_str
 	if (i < num_hugepd) {
 		for (i = i - 1 ; i >= 0; i--, hpdp--)
 			*hpdp = __hugepd(0);
-		kmem_cache_free(cachep, new);
+		if (cachep)
+			kmem_cache_free(cachep, new);
+		else
+			pte_free(mm, new);
 	} else {
 		kmemleak_ignore(new);
 	}
@@ -324,8 +331,7 @@ static void free_hugepd_range(struct mmu
 	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));
+		pgtable_free_tlb(tlb, hugepte, 0);
 	else
 		pgtable_free_tlb(tlb, hugepte,
 				 get_hugepd_cache_index(pdshift - shift));
@@ -639,12 +645,13 @@ 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 && IS_ENABLED(CONFIG_PPC_8xx))
-			pgtable_cache_add(PTE_INDEX_SIZE);
-		else if (pdshift > shift)
-			pgtable_cache_add(pdshift - shift);
-		else if (IS_ENABLED(CONFIG_PPC_FSL_BOOK3E) || IS_ENABLED(CONFIG_PPC_8xx))
+		if (pdshift > shift) {
+			if (!IS_ENABLED(CONFIG_PPC_8xx))
+				pgtable_cache_add(pdshift - shift);
+		} else if (IS_ENABLED(CONFIG_PPC_FSL_BOOK3E) ||
+			   IS_ENABLED(CONFIG_PPC_8xx)) {
 			pgtable_cache_add(PTE_T_ORDER);
+		}
 
 		configured = true;
 	}