Re: [PATCH] target/riscv: Smepmp: Skip applying default rules when address matches

[Alistair Francis]

On Thu, Feb 9, 2023 at 3:53 PM Himanshu Chauhan
<hchauhan@ventanamicro.com> wrote:
>
> When MSECCFG.MML is set, after checking the address range in PMP if the
> asked permissions are not same as programmed in PMP, the default
> permissions are applied. This should only be the case when there
> is no matching address is found.
>
> This patch skips applying default rules when matching address range
> is found. It returns the index of the match PMP entry.
>
> fixes: 824cac681c3 (target/riscv: Fix PMP propagation for tlb)
>
> Signed-off-by: Himanshu Chauhan <hchauhan@ventanamicro.com>

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

> ---
>  target/riscv/pmp.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/target/riscv/pmp.c b/target/riscv/pmp.c
> index d85ad07caa..0dfdb35828 100644
> --- a/target/riscv/pmp.c
> +++ b/target/riscv/pmp.c
> @@ -446,9 +446,12 @@ int pmp_hart_has_privs(CPURISCVState *env, target_ulong 
> addr,
>                  }
>              }
>
> -            if ((privs & *allowed_privs) == privs) {
> -                ret = i;
> -            }
> +            /*
> +             * If matching address range was found, the protection bits
> +             * defined with PMP must be used. We shouldn't fallback on
> +             * finding default privileges.
> +             */
> +            ret = i;
>              break;
>          }
>      }
> --
> 2.39.1
>
>