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

[Palmer Dabbelt]

On Fri, 19 Nov 2021 00:14:19 PST (-0800), wangkefeng.wang at huawei.com wrote:
> Hi Palmer,  ping, it looks this patch is missed...

Sorry about that.  This is on for-next, thanks!

> On 2021/9/27 11:03, Kefeng Wang wrote:
>> 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);
>>   }
>>