Re: [PATCH v7 5/8] xen/riscv: introduce functionality to work with CPU info

[Jan Beulich <jbeulich@xxxxxxxx>]

On 13.09.2024 17:57, Oleksii Kurochko wrote:
> Introduce struct pcpu_info to store pCPU-related information.
> Initially, it includes only processor_id and hart id, but it
> will be extended to include guest CPU information and
> temporary variables for saving/restoring vCPU registers.
> 
> Add set_processor_id() function to set processor_id stored in
> pcpu_info.
> 
> Define smp_processor_id() to provide accurate information,
> replacing the previous "dummy" value of 0.
> 
> Initialize tp registers to point to pcpu_info[0].
> Set processor_id to 0 for logical CPU 0 and store the physical
> CPU ID in pcpu_info[0].
> 
> Introduce helpers for getting hart_id ( physical CPU id in RISC-V
> terms ) from Xen CPU id.
> 
> Removing of <asm/processor.h> inclusion leads to the following
> compilation error:
>   common/keyhandler.c: In function 'dump_registers':
>   common/keyhandler.c:200:13: error: implicit declaration of function
>      'cpu_relax' [-Werror=implicit-function-declaration]
>   200 |             cpu_relax();

What is this paragraph about? It may be stale, or it may be lacking
information / context on what it tries to explain.

> @@ -14,6 +16,22 @@ DECLARE_PER_CPU(cpumask_var_t, cpu_core_mask);
>   */
>  #define park_offline_cpus false
>  
> +/*
> + * Mapping between Xen logical cpu index and hartid.
> + */
> +static inline unsigned long cpuid_to_hartid(unsigned long cpuid)
> +{
> +    return pcpu_info[cpuid].hart_id;
> +}
> +
> +static inline void map_cpuid_to_hartid(unsigned long cpuid,
> +                                       unsigned long hartid)
> +{
> +    pcpu_info[cpuid].hart_id = hartid;
> +}

"map" is ambiguous - it may mean both "get" or "set". May I ask that
this become "set", just like for the processor-ID helper?

Jan