Re: [PATCH 07/20] target/riscv/cpu.c: add .instance_post_init()

[Andrew Jones <ajones@ventanamicro.com>]

On Fri, Aug 25, 2023 at 10:08:40AM -0300, Daniel Henrique Barboza wrote:
> All generic CPUs call riscv_cpu_add_user_properties(). The 'max' CPU
> calls riscv_init_max_cpu_extensions(). Both can be moved to a common
> instance_post_init() callback, implemented in riscv_cpu_post_init(),
> called by all CPUs. The call order then becomes:
> 
> riscv_cpu_init() -> cpu_init() of each CPU -> .instance_post_init()
> 
> A CPU class that wants to add user flags will let us know via the
> 'user_extension_properties' property. Likewise, 'cfg.max_features' will
> determine if any given CPU, regardless of being the 'max' CPU or not,
> wants to enable the maximum amount of extensions.
> 
> In the near future riscv_cpu_post_init() will call the init() function
> of the current accelerator, providing a hook for KVM and TCG accel
> classes to change the init() process of the CPU.
> 
> Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
> ---
>  target/riscv/cpu.c | 20 +++++++++++++++-----
>  1 file changed, 15 insertions(+), 5 deletions(-)
> 
> diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
> index c35d58c64b..f67b782675 100644
> --- a/target/riscv/cpu.c
> +++ b/target/riscv/cpu.c
> @@ -430,8 +430,6 @@ static void riscv_max_cpu_init(Object *obj)
>      mlx = MXL_RV32;
>  #endif
>      set_misa(env, mlx, 0);
> -    riscv_cpu_add_user_properties(obj);
> -    riscv_init_max_cpu_extensions(obj);
>      env->priv_ver = PRIV_VERSION_LATEST;
>  #ifndef CONFIG_USER_ONLY
>      set_satp_mode_max_supported(RISCV_CPU(obj), mlx == MXL_RV32 ?
> @@ -445,7 +443,6 @@ static void rv64_base_cpu_init(Object *obj)
>      CPURISCVState *env = &RISCV_CPU(obj)->env;
>      /* We set this in the realise function */
>      set_misa(env, MXL_RV64, 0);
> -    riscv_cpu_add_user_properties(obj);
>      /* Set latest version of privileged specification */
>      env->priv_ver = PRIV_VERSION_LATEST;
>  #ifndef CONFIG_USER_ONLY
> @@ -569,7 +566,6 @@ static void rv128_base_cpu_init(Object *obj)
>      CPURISCVState *env = &RISCV_CPU(obj)->env;
>      /* We set this in the realise function */
>      set_misa(env, MXL_RV128, 0);
> -    riscv_cpu_add_user_properties(obj);
>      /* Set latest version of privileged specification */
>      env->priv_ver = PRIV_VERSION_LATEST;
>  #ifndef CONFIG_USER_ONLY
> @@ -582,7 +578,6 @@ static void rv32_base_cpu_init(Object *obj)
>      CPURISCVState *env = &RISCV_CPU(obj)->env;
>      /* We set this in the realise function */
>      set_misa(env, MXL_RV32, 0);
> -    riscv_cpu_add_user_properties(obj);
>      /* Set latest version of privileged specification */
>      env->priv_ver = PRIV_VERSION_LATEST;
>  #ifndef CONFIG_USER_ONLY
> @@ -1212,6 +1207,20 @@ static void riscv_cpu_set_irq(void *opaque, int irq, int level)
>  }
>  #endif /* CONFIG_USER_ONLY */
>  
> +static void riscv_cpu_post_init(Object *obj)
> +{
> +    RISCVCPU *cpu = RISCV_CPU(obj);
> +    RISCVCPUClass *rcc = RISCV_CPU_GET_CLASS(cpu);
> +
> +    if (rcc->user_extension_properties) {

It's not yet clear to me why we need 'user_extension_properties'. Can't we
just do the 'object_dynamic_cast(obj, TYPE_RISCV_DYNAMIC_CPU) != NULL'
check here?

> +        riscv_cpu_add_user_properties(obj);
> +    }
> +
> +    if (cpu->cfg.max_features) {

It's also not yet clear why we need max_features. I can't think of any
other models that want max_features besides 'max'. Checking the cpu type
here should be sufficient, no?

> +        riscv_init_max_cpu_extensions(obj);
> +    }
> +}
> +
>  static void riscv_cpu_init(Object *obj)
>  {
>      RISCVCPU *cpu = RISCV_CPU(obj);
> @@ -2019,6 +2028,7 @@ static const TypeInfo riscv_cpu_type_infos[] = {
>          .instance_size = sizeof(RISCVCPU),
>          .instance_align = __alignof__(RISCVCPU),
>          .instance_init = riscv_cpu_init,
> +        .instance_post_init = riscv_cpu_post_init,
>          .abstract = true,
>          .class_size = sizeof(RISCVCPUClass),
>          .class_init = riscv_cpu_class_init,
> -- 
> 2.41.0
> 
>

Thanks,
drew