Re: [PATCH v9 18/19] target/riscv: add 'rva22u64' CPU

[Andrew Jones]

On Thu, Nov 02, 2023 at 07:44:44PM -0300, Daniel Henrique Barboza wrote:
> This CPU was suggested by Alistair [1] and others during the profile
> design discussions. It consists of the bare 'rv64i' CPU with rva22u64
> enabled by default, like an alias of '-cpu rv64i,rva22u64=true'.
> 
> Users now have an even easier way of consuming this user-mode profile by
> doing '-cpu rva22u64'. Extensions can be enabled/disabled at will on top
> of it.
> 
> We can boot Linux with this "user-mode" CPU by doing:
> 
> -cpu rva22u64,sv39=true,s=true,zifencei=true
> 
> [1] 
> https://lore.kernel.org/qemu-riscv/CAKmqyKP7xzZ9Sx=-Lbx2Ob0qCfB7Z+JO944FQ2TQ+49mqo0q_Q@mail.gmail.com/
> 
> Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
> ---
>  target/riscv/cpu-qom.h     |  1 +
>  target/riscv/cpu.c         | 10 ++++++++++
>  target/riscv/tcg/tcg-cpu.c |  9 +++++++++
>  3 files changed, 20 insertions(+)
> 
> diff --git a/target/riscv/cpu-qom.h b/target/riscv/cpu-qom.h
> index ea9a752280..ac38ffc6cf 100644
> --- a/target/riscv/cpu-qom.h
> +++ b/target/riscv/cpu-qom.h
> @@ -37,6 +37,7 @@
>  #define TYPE_RISCV_CPU_BASE64           RISCV_CPU_TYPE_NAME("rv64")
>  #define TYPE_RISCV_CPU_BASE128          RISCV_CPU_TYPE_NAME("x-rv128")
>  #define TYPE_RISCV_CPU_RV64I            RISCV_CPU_TYPE_NAME("rv64i")
> +#define TYPE_RISCV_CPU_RVA22U64         RISCV_CPU_TYPE_NAME("rva22u64")
>  #define TYPE_RISCV_CPU_IBEX             RISCV_CPU_TYPE_NAME("lowrisc-ibex")
>  #define TYPE_RISCV_CPU_SHAKTI_C         RISCV_CPU_TYPE_NAME("shakti-c")
>  #define TYPE_RISCV_CPU_SIFIVE_E31       RISCV_CPU_TYPE_NAME("sifive-e31")
> diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
> index d24ffbf3f8..1f2932031a 100644
> --- a/target/riscv/cpu.c
> +++ b/target/riscv/cpu.c
> @@ -1542,6 +1542,15 @@ static Property riscv_cpu_properties[] = {
>      DEFINE_PROP_END_OF_LIST(),
>  };
>  
> +#if defined(TARGET_RISCV64)
> +static void rva22u64_bare_cpu_init(Object *obj)

The "rva22u64_bare" name is a bit weird, indicating it's both an rva22u64
type and a bare type, which isn't possible. Why not just
rva22u64_cpu_init()?

> +{
> +    rv64i_bare_cpu_init(obj);
> +
> +    RVA22U64.enabled = true;
> +}
> +#endif
> +
>  static const gchar *riscv_gdb_arch_name(CPUState *cs)
>  {
>      RISCVCPU *cpu = RISCV_CPU(cs);
> @@ -1876,6 +1885,7 @@ static const TypeInfo riscv_cpu_type_infos[] = {
>      DEFINE_VENDOR_CPU(TYPE_RISCV_CPU_VEYRON_V1,   rv64_veyron_v1_cpu_init),
>      DEFINE_DYNAMIC_CPU(TYPE_RISCV_CPU_BASE128,  rv128_base_cpu_init),
>      DEFINE_BARE_CPU(TYPE_RISCV_CPU_RV64I, rv64i_bare_cpu_init),
> +    DEFINE_BARE_CPU(TYPE_RISCV_CPU_RVA22U64, rva22u64_bare_cpu_init),

Oh, I see. Because we want to use DEFINE_BARE_CPU() here we wanted bare in
the init function name. Maybe, for self-documentation / less confusion
purposes, we should have a DEFINE_PROFILE_CPU() macro even if it's just an
alias for DEFINE_BARE_CPU().

>  #endif
>  };
>  
> diff --git a/target/riscv/tcg/tcg-cpu.c b/target/riscv/tcg/tcg-cpu.c
> index ef43264cb3..553fb337e7 100644
> --- a/target/riscv/tcg/tcg-cpu.c
> +++ b/target/riscv/tcg/tcg-cpu.c
> @@ -1068,6 +1068,15 @@ static void riscv_cpu_add_profiles(Object *cpu_obj)
>          object_property_add(cpu_obj, profile->name, "bool",
>                              cpu_get_profile, cpu_set_profile,
>                              NULL, (void *)profile);
> +
> +        /*
> +         * CPUs might enable a profile right from the start.
> +         * Enable its mandatory extensions right away in this
> +         * case.
> +         */
> +        if (profile->enabled) {
> +            object_property_set_bool(cpu_obj, profile->name, true, NULL);
> +        }
>      }
>  }
>  
> -- 
> 2.41.0
> 

Other than the naming nits.

Reviewed-by: Andrew Jones <ajones@ventanamicro.com>

Thanks,
drew