[PATCH v2] riscv: mm: Enable PMD split page table lock for RV64

[Kefeng Wang]

After commit 1355c31eeb7e ("asm-generic: pgalloc: provide generic
pmd_alloc_one() and pmd_free_one()"), the main part to support
PMD split page table lock is in asm-generic/pgalloc.h.

The only change is add pgtable_pmd_page_ctor() into alloc_pmd_late(),
then we could enable ARCH_ENABLE_SPLIT_PMD_PTLOCK for RV64.

Reviewed-by: Alexandre Ghiti <alex at ghiti.fr>
Signed-off-by: Kefeng Wang <wangkefeng.wang at huawei.com>
---
v2:
- rebase to v5.15-rc3, update changelog, and add RB

 arch/riscv/Kconfig   | 1 +
 arch/riscv/mm/init.c | 3 ++-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 301a54233c7e..5c4463f30eb0 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -14,6 +14,7 @@ config RISCV
 	def_bool y
 	select ARCH_CLOCKSOURCE_INIT
 	select ARCH_ENABLE_HUGEPAGE_MIGRATION if HUGETLB_PAGE && MIGRATION
+	select ARCH_ENABLE_SPLIT_PMD_PTLOCK if PGTABLE_LEVELS > 2
 	select ARCH_HAS_BINFMT_FLAT
 	select ARCH_HAS_DEBUG_VM_PGTABLE
 	select ARCH_HAS_DEBUG_VIRTUAL if MMU
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index c0cddf0fc22d..1f21375ba86f 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -367,7 +367,8 @@ static phys_addr_t __init alloc_pmd_late(uintptr_t va)
 	unsigned long vaddr;
 
 	vaddr = __get_free_page(GFP_KERNEL);
-	BUG_ON(!vaddr);
+	BUG_ON(!vaddr || !pgtable_pmd_page_ctor(virt_to_page(vaddr)));
+
 	return __pa(vaddr);
 }
 
-- 
2.26.2