RE: [PATCH v4 04/15] xen/cpufreq: refactor cmdline "cpufreq=xxx"

["Penny, Zheng" <penny.zheng@xxxxxxx>]

[Public]

> -----Original Message-----
> From: Penny, Zheng <penny.zheng@xxxxxxx>
> Sent: Monday, April 14, 2025 3:41 PM
> To: xen-devel@xxxxxxxxxxxxxxxxxxxx
> Cc: Huang, Ray <Ray.Huang@xxxxxxx>; Penny, Zheng
> <penny.zheng@xxxxxxx>; Jan Beulich <jbeulich@xxxxxxxx>
> Subject: [PATCH v4 04/15] xen/cpufreq: refactor cmdline "cpufreq=xxx"
>
> A helper function handle_cpufreq_cmdline() is introduced to tidy different 
> handling
> pathes.
> We also add a new helper cpufreq_opts_contain() to ignore and warn user 
> redundant
> setting, like "cpufreq=hwp;hwp;xen"
>
> Signed-off-by: Penny Zheng <Penny.Zheng@xxxxxxx>
> ---
> v2 -> v3:
> - new commit
> ---
> v3 -> v4:
> - add one single helper to do the tidy work
> - ignore and warn user redundant setting
> ---
>  xen/drivers/cpufreq/cpufreq.c | 53 +++++++++++++++++++++++++++++------
>  1 file changed, 45 insertions(+), 8 deletions(-)
>
> diff --git a/xen/drivers/cpufreq/cpufreq.c b/xen/drivers/cpufreq/cpufreq.c 
> index
> e01acc0c2d..79c6444116 100644
> --- a/xen/drivers/cpufreq/cpufreq.c
> +++ b/xen/drivers/cpufreq/cpufreq.c
> @@ -71,6 +71,49 @@ unsigned int __initdata cpufreq_xen_cnt = 1;
>
>  static int __init cpufreq_cmdline_parse(const char *s, const char *e);
>
> +static bool __init cpufreq_opts_contain(enum cpufreq_xen_opt option) {
> +    unsigned int count = cpufreq_xen_cnt;
> +
> +    while ( count )
> +    {
> +        if ( cpufreq_xen_opts[--count] == option )
> +            return true;
> +    }
> +
> +    return false;
> +}
> +
> +static int __init handle_cpufreq_cmdline(enum cpufreq_xen_opt option) {
> +    int ret = 0;
> +
> +    if ( cpufreq_opts_contain(option) )
> +    {
> +        const char *cpufreq_opts_str[] = { "CPUFREQ_xen", "CPUFREQ_hwp"
> + };
> +
> +        printk(XENLOG_WARNING
> +               "Duplicate cpufreq driver option: %s",
> +               cpufreq_opts_str[option - 1]);
> +        return 0;
> +    }
> +
> +    cpufreq_controller = FREQCTL_xen;
> +    cpufreq_xen_opts[cpufreq_xen_cnt++] = option;
> +    switch ( option )
> +    {
> +    case CPUFREQ_hwp:
> +    case CPUFREQ_xen:
> +        xen_processor_pmbits |= XEN_PROCESSOR_PM_PX;
> +        break;
> +    default:
> +        ret = -EINVAL;

I'm thinking since handle_cpufreq_cmdline() is totally internal and has very 
few caller, maybe  ASSERT_UNREACHABLE() is more suitable. Then the function 
itself could become void return.

> +        break;
> +    }
> +
> +    return ret;
> +}
> +
>  static int __init cf_check setup_cpufreq_option(const char *str)  {
>      const char *arg = strpbrk(str, ",:;"); @@ -114,20 +157,14 @@ static int 
> __init
> cf_check setup_cpufreq_option(const char *str)
>
>          if ( choice > 0 || !cmdline_strcmp(str, "xen") )
>          {
> -            xen_processor_pmbits |= XEN_PROCESSOR_PM_PX;
> -            cpufreq_controller = FREQCTL_xen;
> -            cpufreq_xen_opts[cpufreq_xen_cnt++] = CPUFREQ_xen;
> -            ret = 0;
> +            ret = handle_cpufreq_cmdline(CPUFREQ_xen);
>              if ( arg[0] && arg[1] )
>                  ret = cpufreq_cmdline_parse(arg + 1, end);
>          }
>          else if ( IS_ENABLED(CONFIG_INTEL) && choice < 0 &&
>                    !cmdline_strcmp(str, "hwp") )
>          {
> -            xen_processor_pmbits |= XEN_PROCESSOR_PM_PX;
> -            cpufreq_controller = FREQCTL_xen;
> -            cpufreq_xen_opts[cpufreq_xen_cnt++] = CPUFREQ_hwp;
> -            ret = 0;
> +            ret = handle_cpufreq_cmdline(CPUFREQ_hwp);
>              if ( arg[0] && arg[1] )
>                  ret = hwp_cmdline_parse(arg + 1, end);
>          }
> --
> 2.34.1