Re: [Qemu-devel] [PATCH for-3.2 v4 24/28] arm: replace instance_post_init()

[Igor Mammedov <imammedo@redhat.com>]

On Tue, 27 Nov 2018 13:27:57 +0400
Marc-André Lureau <marcandre.lureau@redhat.com> wrote:

> Replace arm_cpu_post_init() instance callback by calling it from leaf
> classes, to avoid potential the ordering issue with interfaces
> post-init.
> 
> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> Suggested-by: Igor Mammedov <imammedo@redhat.com>
> ---
>  target/arm/cpu.h   |  2 ++
>  target/arm/cpu.c   | 15 ++++++++++++---
>  target/arm/cpu64.c | 11 ++++++++++-
>  3 files changed, 24 insertions(+), 4 deletions(-)
> 
> diff --git a/target/arm/cpu.h b/target/arm/cpu.h
> index 2a73fed9a0..84fba2b24b 100644
> --- a/target/arm/cpu.h
> +++ b/target/arm/cpu.h
> @@ -884,6 +884,8 @@ static inline ARMCPU *arm_env_get_cpu(CPUARMState *env)
>      return container_of(env, ARMCPU, env);
>  }
>  
> +void arm_cpu_post_init(Object *obj);
> +
>  uint64_t arm_cpu_mp_affinity(int idx, uint8_t clustersz);
>  
>  #define ENV_GET_CPU(e) CPU(arm_env_get_cpu(e))
> diff --git a/target/arm/cpu.c b/target/arm/cpu.c
> index 60411f6bfe..8a4aae7438 100644
> --- a/target/arm/cpu.c
> +++ b/target/arm/cpu.c
> @@ -734,7 +734,7 @@ static Property arm_cpu_pmsav7_dregion_property =
>  static Property arm_cpu_initsvtor_property =
>              DEFINE_PROP_UINT32("init-svtor", ARMCPU, init_svtor, 0);
>  
> -static void arm_cpu_post_init(Object *obj)
> +void arm_cpu_post_init(Object *obj)
>  {
>      ARMCPU *cpu = ARM_CPU(obj);
>  
> @@ -2094,6 +2094,7 @@ static void arm_host_initfn(Object *obj)
>      ARMCPU *cpu = ARM_CPU(obj);
>  
>      kvm_arm_set_cpu_features_from_host(cpu);
> +    arm_cpu_post_init(ARM_CPU(obj));
>  }
>  
>  static const TypeInfo host_arm_cpu_type_info = {
> @@ -2108,14 +2109,23 @@ static const TypeInfo host_arm_cpu_type_info = {
>  
>  #endif
>  
> +static void arm_cpu_instance_init(Object *obj)
> +{
> +    const ARMCPUInfo *info = object_class_get_class_data(object_get_class(obj));
> +
> +    info->initfn(obj);
> +    arm_cpu_post_init(obj);
> +}
now imagine leaf cpu class call chain:
before patch:
   arm-cpu::initfn()
   cortex-a8::initfn()
      set feature AAA
   device_post_init()
     -> arm_cpu_post_init()
          if (AAA)
             do something   

after patch:
   arm-cpu::initfn()
      -> arm_cpu_post_init()
            if (AAA)
               do something  <--- won't happen anymore
   cortex-a8::initfn()

arm_cpu_post_init() helper has to go to leaf classes only

> +
>  static void cpu_register(const ARMCPUInfo *info)
>  {
>      TypeInfo type_info = {
>          .parent = TYPE_ARM_CPU,
>          .instance_size = sizeof(ARMCPU),
> -        .instance_init = info->initfn,
> +        .instance_init = arm_cpu_instance_init,
>          .class_size = sizeof(ARMCPUClass),
>          .class_init = info->class_init,
> +        .class_data = (void *)info,
>      };
>  
>      type_info.name = g_strdup_printf("%s-" TYPE_ARM_CPU, info->name);
> @@ -2128,7 +2138,6 @@ static const TypeInfo arm_cpu_type_info = {
>      .parent = TYPE_CPU,
>      .instance_size = sizeof(ARMCPU),
>      .instance_init = arm_cpu_initfn,
> -    .instance_post_init = arm_cpu_post_init,
>      .instance_finalize = arm_cpu_finalizefn,
>      .abstract = true,
>      .class_size = sizeof(ARMCPUClass),
> diff --git a/target/arm/cpu64.c b/target/arm/cpu64.c
> index 873f059bf2..dbfc3ee490 100644
> --- a/target/arm/cpu64.c
> +++ b/target/arm/cpu64.c
> @@ -447,14 +447,23 @@ static void aarch64_cpu_class_init(ObjectClass *oc, void *data)
>      cc->gdb_arch_name = aarch64_gdb_arch_name;
>  }
>  
> +static void aarch64_cpu_instance_init(Object *obj)
> +{
> +    const ARMCPUInfo *info = object_class_get_class_data(object_get_class(obj));
> +
> +    info->initfn(obj);
> +    arm_cpu_post_init(obj);
> +}
> +
>  static void aarch64_cpu_register(const ARMCPUInfo *info)
>  {
>      TypeInfo type_info = {
>          .parent = TYPE_AARCH64_CPU,
>          .instance_size = sizeof(ARMCPU),
> -        .instance_init = info->initfn,
> +        .instance_init = aarch64_cpu_instance_init,
>          .class_size = sizeof(ARMCPUClass),
>          .class_init = info->class_init,
> +        .class_data = (void *)info,
>      };
>  
>      type_info.name = g_strdup_printf("%s-" TYPE_ARM_CPU, info->name);