[PATCH 4/8] lib: sbi_hart: reset sstateen and hstateen

[Anup Patel]

On Tue, Apr 15, 2025 at 8:13 PM Radim Krčmář <rkrcmar at ventanamicro.com> wrote:
>
> Not resetting sstateen is a potential security hole, because U might be
> able to access state that S does not properly context-switch.
> Similar for hstateen with VS and HS.
>
> Signed-off-by: Radim Krčmář <rkrcmar at ventanamicro.com>

LGTM.

Reviewed-by: Anup Patel <anup at brainfault.org>

Regards,
Anup

> ---
>  lib/sbi/sbi_hart.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c
> index b66b89f6bc51..c280c0b3e85e 100644
> --- a/lib/sbi/sbi_hart.c
> +++ b/lib/sbi/sbi_hart.c
> @@ -111,6 +111,12 @@ static void mstatus_init(struct sbi_scratch *scratch)
>                         mstateen_val &= ~SMSTATEEN0_CTR;
>
>                 csr_write64(CSR_MSTATEEN0, mstateen_val);
> +
> +               if (misa_extension('S'))
> +                       csr_write(CSR_SSTATEEN0, 0);
> +
> +               if (misa_extension('H'))
> +                       csr_write64(CSR_HSTATEEN0, (uint64_t)0);
>         }
>
>         if (sbi_hart_priv_version(scratch) >= SBI_HART_PRIV_VER_1_12) {
> --
> 2.48.1
>
>
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