[PATCH] RISC-V: mm: Fix set_satp_mode() for platform not having Sv57

[Palmer Dabbelt]

On Thu, 21 Apr 2022 02:30:05 PDT (-0700), apatel at ventanamicro.com wrote:
> Hi Palmer,
>
> On Tue, Apr 12, 2022 at 9:04 AM Anup Patel <apatel at ventanamicro.com> wrote:
>>
>> When Sv57 is not available the satp.MODE test in set_satp_mode() will
>> fail and lead to pgdir re-programming for Sv48. The pgdir re-programming
>> will fail as well due to pre-existing pgdir entry used for Sv57 and as
>> a result kernel fails to boot on RISC-V platform not having Sv57.
>>
>> To fix above issue, we should clear the pgdir memory in set_satp_mode()
>> before re-programming.
>>
>> Fixes: 011f09d12052 ("riscv: mm: Set sv57 on defaultly")
>> Reported-by: Mayuresh Chitale <mchitale at ventanamicro.com>
>> Signed-off-by: Anup Patel <apatel at ventanamicro.com>
>
> Can this be considered for 5.18-rcX ?

Sorry, there's a queue but I just say this one at the top and it's super 
simple so I'm going to take it now -- IRC is good to ping this sort of 
stuff.

It's in fixes.

Thanks!

>
> Regards,
> Anup
>
>> ---
>>  arch/riscv/mm/init.c | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
>> index 9535bea8688c..b0793dc0c291 100644
>> --- a/arch/riscv/mm/init.c
>> +++ b/arch/riscv/mm/init.c
>> @@ -718,6 +718,7 @@ static __init void set_satp_mode(void)
>>                 if (!check_l4) {
>>                         disable_pgtable_l5();
>>                         check_l4 = true;
>> +                       memset(early_pg_dir, 0, PAGE_SIZE);
>>                         goto retry;
>>                 }
>>                 disable_pgtable_l4();
>> --
>> 2.25.1
>>