linux-kernel - [RFC PATCH v2 11/20] powerpc/mm: Complement huge_pte

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Date: Fri, 17 May 2024 21:00:05 +0200
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Andrew Morton <akpm@...ux-foundation.org>,
	Jason Gunthorpe <jgg@...dia.com>,
	Peter Xu <peterx@...hat.com>,
	Oscar Salvador <osalvador@...e.de>,
	Michael Ellerman <mpe@...erman.id.au>,
	Nicholas Piggin <npiggin@...il.com>
Cc: Christophe Leroy <christophe.leroy@...roup.eu>,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org,
	linuxppc-dev@...ts.ozlabs.org
Subject: [RFC PATCH v2 11/20] powerpc/mm: Complement huge_pte_alloc() for all non HUGEPD setups

huge_pte_alloc() for non-HUGEPD targets is reserved for 8xx at the
moment. In order to convert other targets for non-HUGEPD, complement
huge_pte_alloc() to support any standard cont-PxD setup.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/mm/hugetlbpage.c | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index 42b12e1ec851..f8aefa1e7363 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -195,11 +195,34 @@ pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
 pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
 		      unsigned long addr, unsigned long sz)
 {
-	pmd_t *pmd = pmd_off(mm, addr);
+	pgd_t *pgd;
+	p4d_t *p4d;
+	pud_t *pud;
+	pmd_t *pmd;
+
+	addr &= ~(sz - 1);
+	pgd = pgd_offset(mm, addr);
+
+	p4d = p4d_offset(pgd, addr);
+	if (sz >= PGDIR_SIZE)
+		return (pte_t *)p4d;
+
+	pud = pud_alloc(mm, p4d, addr);
+	if (!pud)
+		return NULL;
+	if (sz >= PUD_SIZE)
+		return (pte_t *)pud;
+
+	pmd = pmd_alloc(mm, pud, addr);
+	if (!pmd)
+		return NULL;
 
 	if (sz < PMD_SIZE)
 		return pte_alloc_huge(mm, pmd, addr, sz);
 
+	if (!IS_ENABLED(CONFIG_PPC_8xx))
+		return (pte_t *)pmd;
+
 	if (sz != SZ_8M)
 		return NULL;
 	if (!pte_alloc_huge(mm, pmd, addr, sz))
-- 
2.44.0