Re: [PATCH v5 07/16] fs/resctrl: Introduce resctrl_set_kmode_support() to register supported modes

[Reinette Chatre]

Hi Babu,

On 8/26/26 12:32 PM, Babu Moger wrote:

> diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
> index 3c53f3f74e5a..3bb0e3a203ac 100644
> --- a/fs/resctrl/rdtgroup.c
> +++ b/fs/resctrl/rdtgroup.c
> @@ -892,6 +892,19 @@ static int rdtgroup_rmid_show(struct kernfs_open_file *of,
>  	return ret;
>  }
>  
> +/**
> + * resctrl_set_kmode_support() - Register a supported kernel mode
> + * @kmode:	Kernel mode policy supported by the architecture.

How is "Kernel mode" different from "Kernel mode policy"?

> + *
> + * Set the corresponding bit in resctrl_kcfg.caps.kmode_sup so @kmode
> + * is visible to the resctrl file system.

Verbatim description of what can be seen from the code.

> + */
> +void resctrl_set_kmode_support(enum resctrl_kernel_mode kmode)
> +{
> +	if (kmode < RESCTRL_NUM_KERNEL_MODES)
> +		__set_bit(kmode, resctrl_kcfg.caps.kmode_sup);
> +}
> +
>  #ifdef CONFIG_PROC_CPU_RESCTRL
>  /*
>   * A task can only be part of one resctrl control group and of one monitor
> diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
> index 8b30eef835aa..051aece77eb9 100644
> --- a/include/linux/resctrl.h
> +++ b/include/linux/resctrl.h
> @@ -729,6 +729,23 @@ enum resctrl_kernel_mode {
>  
>  #define RESCTRL_NUM_KERNEL_MODES (RESCTRL_KMODE_LAST + 1)
>  
> +/**
> + * resctrl_set_kmode_support() - Register a supported kernel mode
> + * @kmode: Kernel mode supported by the architecture.
> + *
> + * Set the corresponding bit in resctrl_kcfg.caps.kmode_sup so @kmode

No need to describe resctrl fs internal details here.

> + * can be exposed through the resctrl filesystem.
> + * RESCTRL_INHERIT_USER is registered by resctrl_kmode_init() and does
> + * not need to be registered again.
> + *
> + * Architectures use this interface during resctrl initialization to
> + * advertise supported kernel modes. Registration of a mode indicates
> + * architectural support only. The final decision to expose and enable
> + * a mode is made by resctrl based on system capabilities and
> + * configuration.
> + */
> +void resctrl_set_kmode_support(enum resctrl_kernel_mode kmode);
> +
>  /**
>   * resctrl_arch_configure_kmode() - Program kernel mode association
>   * @cpu_mask:	CPUs to assign the kernel mode on.

Reinette