Re: [PATCH v3 1/2] target/riscv: Restrict mideleg/medeleg/medelegh access to S-mode harts

["Nutty Liu" <liujingqi@lanxincomputing.com>]

On 7/1/2025 11:00 AM, Jay Chang wrote:
> RISC-V Privileged Spec states:
> "In harts with S-mode, the medeleg and mideleg registers must exist, and
> setting a bit in medeleg or mideleg will delegate the corresponding trap
> , when occurring in S-mode or U-mode, to the S-mode trap handler. In
> harts without S-mode, the medeleg and mideleg registers should not
> exist."
>
> Add smode predicate to ensure these CSRs are only accessible when S-mode
> is supported.
>
> Reviewed-by: Frank Chang <frank.chang@sifive.com>
> Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
> Signed-off-by: Jay Chang <jay.chang@sifive.com>
> ---
>   target/riscv/csr.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/target/riscv/csr.c b/target/riscv/csr.c
> index 6296ecd1e1..0e0ad37654 100644
> --- a/target/riscv/csr.c
> +++ b/target/riscv/csr.c
> @@ -5862,8 +5862,8 @@ riscv_csr_operations csr_ops[CSR_TABLE_SIZE] = {
>                             NULL,                read_mstatus_i128           },
>       [CSR_MISA]        = { "misa",       any,   read_misa,    write_misa,
>                             NULL,                read_misa_i128              },
> -    [CSR_MIDELEG]     = { "mideleg",    any,   NULL, NULL,   rmw_mideleg   },
> -    [CSR_MEDELEG]     = { "medeleg",    any,   read_medeleg, write_medeleg },
> +    [CSR_MIDELEG]     = { "mideleg",    smode,   NULL, NULL,   rmw_mideleg   },
> +    [CSR_MEDELEG]     = { "medeleg",    smode,   read_medeleg, write_medeleg },
>       [CSR_MIE]         = { "mie",        any,   NULL, NULL,   rmw_mie       },
>       [CSR_MTVEC]       = { "mtvec",      any,   read_mtvec,   write_mtvec   },
>       [CSR_MCOUNTEREN]  = { "mcounteren", umode, read_mcounteren,
> @@ -5871,7 +5871,7 @@ riscv_csr_operations csr_ops[CSR_TABLE_SIZE] = {
>   
>       [CSR_MSTATUSH]    = { "mstatush",   any32, read_mstatush,
>                             write_mstatush                                   },
> -    [CSR_MEDELEGH]    = { "medelegh",   any32, read_zero, write_ignore,
> +    [CSR_MEDELEGH]    = { "medelegh",   smode32, read_zero, write_ignore,
>                             .min_priv_ver = PRIV_VERSION_1_13_0              },
>       [CSR_HEDELEGH]    = { "hedelegh",   hmode32, read_hedelegh, write_hedelegh,
>                             .min_priv_ver = PRIV_VERSION_1_13_0              },

Reviewed-by: Nutty Liu<liujingqi@lanxincomputing.com>

Thanks,
Nutty