Re: [PATCH v2 7/8] target/riscv: Force disable extensions if priv spec version does not match

[Alistair Francis <alistair23@gmail.com>]

On Thu, May 12, 2022 at 12:52 AM Anup Patel <apatel@ventanamicro.com> wrote:
>
> We should disable extensions in riscv_cpu_realize() if minimum required
> priv spec version is not satisfied. This also ensures that machines with
> priv spec v1.11 (or lower) cannot enable H, V, and various multi-letter
> extensions.
>
> Fixes: a775398be2e ("target/riscv: Add isa extenstion strings to the
> device tree")
> Signed-off-by: Anup Patel <apatel@ventanamicro.com>

This will potentially confuse users as we just disable the extension
without telling them.

Could we not just leave this as is and let users specify the
extensions they want? Then it's up to them to specify the correct
combinations

Alistair

> ---
>  target/riscv/cpu.c | 34 ++++++++++++++++++++++++++++++++++
>  1 file changed, 34 insertions(+)
>
> diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
> index f3b61dfd63..25a4ba3e22 100644
> --- a/target/riscv/cpu.c
> +++ b/target/riscv/cpu.c
> @@ -541,6 +541,40 @@ static void riscv_cpu_realize(DeviceState *dev, Error **errp)
>          set_priv_version(env, priv_version);
>      }
>
> +    /* Force disable extensions if priv spec version does not match */
> +    if (env->priv_ver < PRIV_VERSION_1_12_0) {
> +        cpu->cfg.ext_h = false;
> +        cpu->cfg.ext_v = false;
> +        cpu->cfg.ext_zfh = false;
> +        cpu->cfg.ext_zfhmin = false;
> +        cpu->cfg.ext_zfinx = false;
> +        cpu->cfg.ext_zhinx = false;
> +        cpu->cfg.ext_zhinxmin = false;
> +        cpu->cfg.ext_zdinx = false;
> +        cpu->cfg.ext_zba = false;
> +        cpu->cfg.ext_zbb = false;
> +        cpu->cfg.ext_zbc = false;
> +        cpu->cfg.ext_zbkb = false;
> +        cpu->cfg.ext_zbkc = false;
> +        cpu->cfg.ext_zbkx = false;
> +        cpu->cfg.ext_zbs = false;
> +        cpu->cfg.ext_zk = false;
> +        cpu->cfg.ext_zkn = false;
> +        cpu->cfg.ext_zknd = false;
> +        cpu->cfg.ext_zkne = false;
> +        cpu->cfg.ext_zknh = false;
> +        cpu->cfg.ext_zkr = false;
> +        cpu->cfg.ext_zks = false;
> +        cpu->cfg.ext_zksed = false;
> +        cpu->cfg.ext_zksh = false;
> +        cpu->cfg.ext_zkt = false;
> +        cpu->cfg.ext_zve32f = false;
> +        cpu->cfg.ext_zve64f = false;
> +        cpu->cfg.ext_svinval = false;
> +        cpu->cfg.ext_svnapot = false;
> +        cpu->cfg.ext_svpbmt = false;
> +    }
> +
>      if (cpu->cfg.mmu) {
>          riscv_set_feature(env, RISCV_FEATURE_MMU);
>      }
> --
> 2.34.1
>
>