Re: [PATCH] RISC-V: mm: Fix set_satp_mode() for platform not having Sv57
From: 潘庆霖
Date: Fri Apr 15 2022 - 01:07:31 EST
Hi Anup,
>
> 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@xxxxxxxxxxxxxxxx>
> Signed-off-by: Anup Patel <apatel@xxxxxxxxxxxxxxxx>
> ---
> 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();
> --
I find it that the set_satp_mode function is in .init.text section which begins at 0x80800000.
And its pgd_index in both Sv48 and Sv57 will be 0. So it may not be necessary to clear the
early_pg_dir when the kernel find Sv57 is not supported? And may I get the steps of reproduction
from you?
Yours,
Qinglin
</apatel@xxxxxxxxxxxxxxxx></mchitale@xxxxxxxxxxxxxxxx>