Re: [RFC PATCH 09/13] cpus: Add const-qualified CPU environment accessors

On 8/20/26 03:47, Philippe Mathieu-Daudé wrote:
> Introduce const-qualified variants of cpu_env() and
> env_archcpu(), to safely access CPU architecture
> state when it should not be modified.
> 
> Signed-off-by: Philippe Mathieu-Daudé <[email protected]>
> ---
>   include/exec/cpu-common.h | 11 +++++++++++
>   include/hw/core/cpu.h     |  6 ++++++
>   2 files changed, 17 insertions(+)
> 
> diff --git a/include/exec/cpu-common.h b/include/exec/cpu-common.h
> index 6594f7fa1be..f3a3799f451 100644
> --- a/include/exec/cpu-common.h
> +++ b/include/exec/cpu-common.h
> @@ -79,6 +79,17 @@ static inline bool cpu_loop_exit_requested(const CPUState *cpu)
>   }
>   #endif /* CONFIG_TCG */
>   
> +/**
> + * env_archcpu_const(env)
> + * @env: The architecture environment (const).
> + *
> + * Return the const ArchCPU associated with the environment.
> + */
> +static inline const ArchCPU *env_archcpu_const(const CPUArchState *env)
> +{
> +    return (const void *)env - sizeof(CPUState);
> +}
> +
>   /**
>    * env_archcpu(env)
>    * @env: The architecture environment
> diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h
> index 81af7b9ee1a..59f777f3f15 100644
> --- a/include/hw/core/cpu.h
> +++ b/include/hw/core/cpu.h
> @@ -594,6 +594,12 @@ struct CPUState {
>   QEMU_BUILD_BUG_ON(offsetof(CPUState, neg) !=
>                     sizeof(CPUState) - sizeof(CPUNegativeOffsetState));
>   
> +static inline const CPUArchState *cpu_env_const(const CPUState *cpu)
> +{
> +    /* We validate that CPUArchState follows CPUState in cpu-target.c */
> +    return (const CPUArchState *)(cpu + 1);
> +}
> +
>   static inline CPUArchState *cpu_env(CPUState *cpu)
>   {
>       /* We validate that CPUArchState follows CPUState in cpu-target.c */

I wonder if we can use _Generic to make this automatic, rather than have to choose between 
two different function names.


r~