Re: [PATCH v3] x86/cpufreq: Add Kconfig option for CPU frequency scaling

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 13/02/2026 10:28 pm, Stefano Stabellini wrote:
> diff --git a/xen/arch/x86/platform_hypercall.c 
> b/xen/arch/x86/platform_hypercall.c
> index c6c5135806..a4669090e0 100644
> --- a/xen/arch/x86/platform_hypercall.c
> +++ b/xen/arch/x86/platform_hypercall.c
> @@ -485,6 +485,7 @@ ret_t do_platform_op(
>          ret = acpi_enter_sleep(&op->u.enter_acpi_sleep);
>          break;
>  
> +#ifdef CONFIG_CPUFREQ
>      case XENPF_change_freq:
>          ret = -ENOSYS;
>          if ( cpufreq_controller != FREQCTL_dom0_kernel )
> @@ -544,6 +545,7 @@ ret_t do_platform_op(
>              ret = -EFAULT;
>          break;
>      }
> +#endif

You must not hide case labels like this.  Instead, use:

    case XENPF_change_freq:
        ret = -ENOSYS;
        if ( !IS_ENABLED(CONFIG_CPUFREQ) )
            break;
        ...

which in turn ...

>  
>      case XENPF_set_processor_pminfo:
>          switch ( op->u.set_pminfo.type )
> @@ -936,7 +938,7 @@ ret_t do_platform_op(
>          break;
>      }
>  
> - out:
> + out: __maybe_unused;
>      spin_unlock(&xenpf_lock);

... removes the need for this hunk.

> diff --git a/xen/drivers/acpi/pm-op.c b/xen/drivers/acpi/pm-op.c
> index 07bddc58d9..f5caeebb9a 100644
> --- a/xen/drivers/acpi/pm-op.c
> +++ b/xen/drivers/acpi/pm-op.c
> @@ -367,7 +367,8 @@ int do_pm_op(struct xen_sysctl_pm_op *op)
>          return ret;
>      }
>  
> -    if ( op->cpuid >= nr_cpu_ids || !cpu_online(op->cpuid) )
> +    if ( op->cpuid >= nr_cpu_ids || !cpu_online(op->cpuid) ||
> +         !IS_ENABLED(CPUFREQ) )

Everywhere else in this patch, CONFIG_CPUFREQ.

You won't get a compile error for typo-ing a name inside IF_ENABLED(),
but it won't function correctly either.

~Andrew