Re: [PATCH v2 05/22] target/riscv: Allow setting CPU feature from machine/device emulation

[Alistair Francis <alistair23@gmail.com>]

On Thu, Sep 2, 2021 at 9:42 PM Anup Patel <anup.patel@wdc.com> wrote:
>
> The machine or device emulation should be able to force set certain
> CPU features because:
> 1) We can have certain CPU features which are in-general optional
>    but implemented by RISC-V CPUs on machine.
> 2) We can have devices which require certain CPU feature. For example,
>    AIA IMSIC devices expects AIA CSRs implemented by RISC-V CPUs.
>
> Signed-off-by: Anup Patel <anup.patel@wdc.com>

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

Alistair

> ---
>  target/riscv/cpu.c | 11 +++--------
>  target/riscv/cpu.h |  5 +++++
>  2 files changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
> index 0ade6ad144..9dc9d04923 100644
> --- a/target/riscv/cpu.c
> +++ b/target/riscv/cpu.c
> @@ -137,11 +137,6 @@ static void set_vext_version(CPURISCVState *env, int vext_ver)
>      env->vext_ver = vext_ver;
>  }
>
> -static void set_feature(CPURISCVState *env, int feature)
> -{
> -    env->features |= (1ULL << feature);
> -}
> -
>  static void set_resetvec(CPURISCVState *env, target_ulong resetvec)
>  {
>  #ifndef CONFIG_USER_ONLY
> @@ -423,18 +418,18 @@ static void riscv_cpu_realize(DeviceState *dev, Error **errp)
>      }
>
>      if (cpu->cfg.mmu) {
> -        set_feature(env, RISCV_FEATURE_MMU);
> +        riscv_set_feature(env, RISCV_FEATURE_MMU);
>      }
>
>      if (cpu->cfg.pmp) {
> -        set_feature(env, RISCV_FEATURE_PMP);
> +        riscv_set_feature(env, RISCV_FEATURE_PMP);
>
>          /*
>           * Enhanced PMP should only be available
>           * on harts with PMP support
>           */
>          if (cpu->cfg.epmp) {
> -            set_feature(env, RISCV_FEATURE_EPMP);
> +            riscv_set_feature(env, RISCV_FEATURE_EPMP);
>          }
>      }
>
> diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
> index 59b36f758f..6fe1cc67e5 100644
> --- a/target/riscv/cpu.h
> +++ b/target/riscv/cpu.h
> @@ -323,6 +323,11 @@ static inline bool riscv_feature(CPURISCVState *env, int feature)
>      return env->features & (1ULL << feature);
>  }
>
> +static inline void riscv_set_feature(CPURISCVState *env, int feature)
> +{
> +    env->features |= (1ULL << feature);
> +}
> +
>  #include "cpu_user.h"
>  #include "cpu_bits.h"
>
> --
> 2.25.1
>
>