Re: [PATCH v5 1/2] target/riscv: Align pmp size to pmp-granularity

[Chao Liu <chao.liu.zevorn@gmail.com>]

On Wed, May 20, 2026 at 02:36:05PM +0800, Jay Chang wrote:
> When configuring pmpcfg (TOR, NA4, or NAPOT) and pmpaddr, if the
> value is smaller than the PMP granularity, it needs to be aligned
> to the PMP granularity.
> 
> Signed-off-by: Jay Chang <jay.chang@sifive.com>
> Reviewed-by: Frank Chang <frank.chang@sifive.com>
> Reviewed-by: Daniel Henrique Barboza <daniel.barboza@oss.qualcomm.com>
Reviewed-by: Chao Liu <chao.liu.zevorn@gmail.com>

> ---
>  target/riscv/pmp.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/target/riscv/pmp.c b/target/riscv/pmp.c
> index a71091a316..8adf7c9719 100644
> --- a/target/riscv/pmp.c
> +++ b/target/riscv/pmp.c
> @@ -179,11 +179,12 @@ static bool pmp_write_cfg(CPURISCVState *env, uint32_t pmp_index, uint8_t val)
>              }
>              /*
>               * When granularity g >= 1 (i.e., granularity > 4 bytes),
> -             * the NA4 (Naturally Aligned 4-byte) mode is not selectable
> +             * the NA4 (Naturally Aligned 4-byte) mode is not selectable.
> +             * In this case, an NA4 setting is reinterpreted as a NAPOT mode.
>               */
>              if ((riscv_cpu_cfg(env)->pmp_granularity >
>                  MIN_RISCV_PMP_GRANULARITY) && (a_field == PMP_AMATCH_NA4)) {
> -                    return false;
> +                    val |= PMP_AMATCH;
>              }
>              env->pmp_state.pmp[pmp_index].cfg_reg = val;
>              pmp_update_rule_addr(env, pmp_index);
> @@ -263,6 +264,11 @@ void pmp_update_rule_addr(CPURISCVState *env, uint32_t pmp_index)
>          break;
>  
>      case PMP_AMATCH_NAPOT:
> +        /* Bits [g-2:0] need to be all one to align pmp granularity */
> +        if (g >= 2) {
> +            this_addr = deposit64(this_addr, 0, g - 1, -1ULL);
> +        }
> +
>          pmp_decode_napot(this_addr, &sa, &ea);
>          break;
>  
> -- 
> 2.48.1
>