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References: <20220412033335.1384230-1-apatel@ventanamicro.com>
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From:   Atish Patra <atishp@atishpatra.org>
Date:   Thu, 14 Apr 2022 22:47:03 -0700
Message-ID: <CAOnJCUJUy1sE49hu6yyUzdsVwnLMXA0zOPBMzn8MTTYUdSnWtg@mail.gmail.com>
Subject: Re: [PATCH] RISC-V: mm: Fix set_satp_mode() for platform not having Sv57
To:     Anup Patel <apatel@ventanamicro.com>
Cc:     Palmer Dabbelt <palmer@dabbelt.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Alexandre Ghiti <alexandre.ghiti@canonical.com>,
        Alistair Francis <Alistair.Francis@wdc.com>,
        Anup Patel <anup@brainfault.org>,
        linux-riscv <linux-riscv@lists.infradead.org>,
        "linux-kernel@vger.kernel.org List" <linux-kernel@vger.kernel.org>,
        Mayuresh Chitale <mchitale@ventanamicro.com>
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On Mon, Apr 11, 2022 at 8:34 PM Anup Patel <apatel@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@ventanamicro.com>
> Signed-off-by: Anup Patel <apatel@ventanamicro.com>
> ---
>  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
>

Reviewed-by: Atish Patra <atishp@rivosinc.com>


-- 
Regards,
Atish