[PATCH v6 7/9] arm64/mm: Override arch_wants_pte_order()

[Ryan Roberts]

Define an arch-specific override of arch_wants_pte_order() so that when
anon_orders=recommend is set, large folios will be allocated for
anonymous memory with an order that is compatible with arm64's HPA uarch
feature.

Reviewed-by: Yu Zhao <yuzhao at google.com>
Signed-off-by: Ryan Roberts <ryan.roberts at arm.com>
---
 arch/arm64/include/asm/pgtable.h | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 7f7d9b1df4e5..e3d2449dec5c 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -1110,6 +1110,16 @@ extern pte_t ptep_modify_prot_start(struct vm_area_struct *vma,
 extern void ptep_modify_prot_commit(struct vm_area_struct *vma,
 				    unsigned long addr, pte_t *ptep,
 				    pte_t old_pte, pte_t new_pte);
+
+#define arch_wants_pte_order arch_wants_pte_order
+static inline int arch_wants_pte_order(void)
+{
+	/*
+	 * Many arm64 CPUs support hardware page aggregation (HPA), which can
+	 * coalesce 4 contiguous pages into a single TLB entry.
+	 */
+	return 2;
+}
 #endif /* !__ASSEMBLY__ */
 
 #endif /* __ASM_PGTABLE_H */
-- 
2.25.1