Re: [RFC PATCH 05/16] target/riscv: Add CPU options of WorldGuard CPU extension

[Alistair Francis]

On Wed, Jun 12, 2024 at 6:17 PM Jim Shu <jim.shu@sifive.com> wrote:
>
> We define CPU options for WG CSR support in RISC-V CPUs which
> can be set by machine/device emulation. The RISC-V CSR emulation
> will also check this feature for emulating WG CSRs.
>
> Signed-off-by: Jim Shu <jim.shu@sifive.com>
> ---
>  target/riscv/cpu.c         |  8 ++++++++
>  target/riscv/cpu_cfg.h     |  3 +++
>  target/riscv/tcg/tcg-cpu.c | 11 +++++++++++
>  3 files changed, 22 insertions(+)
>
> diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
> index 69a08e8c2c..d70eedf957 100644
> --- a/target/riscv/cpu.c
> +++ b/target/riscv/cpu.c
> @@ -204,6 +204,9 @@ const RISCVIsaExtData isa_edata_arr[] = {
>      ISA_EXT_DATA_ENTRY(xtheadmempair, PRIV_VERSION_1_11_0, 
> ext_xtheadmempair),
>      ISA_EXT_DATA_ENTRY(xtheadsync, PRIV_VERSION_1_11_0, ext_xtheadsync),
>      ISA_EXT_DATA_ENTRY(xventanacondops, PRIV_VERSION_1_12_0, 
> ext_XVentanaCondOps),
> +    ISA_EXT_DATA_ENTRY(smwg, PRIV_VERSION_1_12_0, ext_smwg),
> +    ISA_EXT_DATA_ENTRY(smwgd, PRIV_VERSION_1_12_0, ext_smwgd),
> +    ISA_EXT_DATA_ENTRY(sswg, PRIV_VERSION_1_12_0, ext_sswg),
>
>      DEFINE_PROP_END_OF_LIST(),
>  };
> @@ -1595,6 +1598,11 @@ const RISCVCPUMultiExtConfig 
> riscv_cpu_experimental_exts[] = {
>  const RISCVCPUMultiExtConfig riscv_cpu_named_features[] = {
>      MULTI_EXT_CFG_BOOL("zic64b", ext_zic64b, true),
>
> +    /* RISC-V WorldGuard v0.4 */
> +    MULTI_EXT_CFG_BOOL("x-smwg", ext_smwg, false),
> +    MULTI_EXT_CFG_BOOL("x-smwgd", ext_smwgd, false),
> +    MULTI_EXT_CFG_BOOL("x-sswg", ext_sswg, false),

We want to add the functionality then expose the properties, as this
is user accessible and we want to maintain bistability.

I understand this doesn't break the build, but it's a bit strange to
allow users to enable something when at this point it doesn't yet work

Alistair

> +
>      DEFINE_PROP_END_OF_LIST(),
>  };
>
> diff --git a/target/riscv/cpu_cfg.h b/target/riscv/cpu_cfg.h
> index e1e4f32698..23e779ae08 100644
> --- a/target/riscv/cpu_cfg.h
> +++ b/target/riscv/cpu_cfg.h
> @@ -120,6 +120,9 @@ struct RISCVCPUConfig {
>      bool ext_ssaia;
>      bool ext_sscofpmf;
>      bool ext_smepmp;
> +    bool ext_smwg;
> +    bool ext_smwgd;
> +    bool ext_sswg;
>      bool rvv_ta_all_1s;
>      bool rvv_ma_all_1s;
>
> diff --git a/target/riscv/tcg/tcg-cpu.c b/target/riscv/tcg/tcg-cpu.c
> index 683f604d9f..dc86e6e1d5 100644
> --- a/target/riscv/tcg/tcg-cpu.c
> +++ b/target/riscv/tcg/tcg-cpu.c
> @@ -726,6 +726,17 @@ void riscv_cpu_validate_set_extensions(RISCVCPU *cpu, 
> Error **errp)
>          cpu->pmu_avail_ctrs = 0;
>      }
>
> +    /* RISC-V WorldGuard */
> +    if (cpu->cfg.ext_sswg && !cpu->cfg.ext_smwg) {
> +        error_setg(errp, "Sswg extension requires Smwg extension");
> +        return;
> +    }
> +
> +    if (cpu->cfg.ext_smwgd != cpu->cfg.ext_sswg) {
> +        error_setg(errp, "Smwgd/Sswg extensions should be enabled together");
> +        return;
> +    }
> +
>      /*
>       * Disable isa extensions based on priv spec after we
>       * validated and set everything we need.
> --
> 2.17.1
>
>