linux-kernel - Re: [PATCH v6 29/42] x86/resctrl: Move get_config

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Message-ID: <3749ab92-6f6e-43b4-8147-22775e31d21b@intel.com>
Date: Wed, 19 Feb 2025 17:27:41 -0800
From: Reinette Chatre <reinette.chatre@...el.com>
To: James Morse <james.morse@....com>, <x86@...nel.org>,
	<linux-kernel@...r.kernel.org>
CC: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>, H Peter Anvin <hpa@...or.com>, Babu Moger
	<Babu.Moger@....com>, <shameerali.kolothum.thodi@...wei.com>, "D Scott
 Phillips OS" <scott@...amperecomputing.com>, <carl@...amperecomputing.com>,
	<lcherian@...vell.com>, <bobo.shaobowang@...wei.com>,
	<tan.shaopeng@...itsu.com>, <baolin.wang@...ux.alibaba.com>, Jamie Iles
	<quic_jiles@...cinc.com>, Xin Hao <xhao@...ux.alibaba.com>,
	<peternewman@...gle.com>, <dfustini@...libre.com>, <amitsinght@...vell.com>,
	David Hildenbrand <david@...hat.com>, Rex Nie <rex.nie@...uarmicro.com>,
	"Dave Martin" <dave.martin@....com>, Koba Ko <kobak@...dia.com>, Shanker
 Donthineni <sdonthineni@...dia.com>, Shaopeng Tan
	<tan.shaopeng@...fujitsu.com>, "Tony Luck" <tony.luck@...el.com>
Subject: Re: [PATCH v6 29/42] x86/resctrl: Move get_config_index() to a header

Hi James,

On 2/7/25 10:18 AM, James Morse wrote:
> get_config_index() is used by the architecture specific code to map a
> CLOSID+type pair to an index in the configuration arrays.
> 
> MPAM needs to do this too to preserve the ABI to user-space, there is
> no reason to do it differently.
> 
> Move the helper to a header file.
> 
> Co-developed-by: Dave Martin <Dave.Martin@....com>
> Signed-off-by: Dave Martin <Dave.Martin@....com>
> Signed-off-by: James Morse <james.morse@....com>
> Tested-by: Carl Worth <carl@...amperecomputing.com> # arm64
> Tested-by: Shaopeng Tan <tan.shaopeng@...fujitsu.com>
> Reviewed-by: Shaopeng Tan <tan.shaopeng@...fujitsu.com>
> Reviewed-by: Tony Luck <tony.luck@...el.com>
> ---
> Changes since v1:
>  * Reindent resctrl_get_config_index() as per coding-style.rst rules.
> ---
>  arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 19 +++----------------
>  include/linux/resctrl.h                   | 15 +++++++++++++++
>  2 files changed, 18 insertions(+), 16 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> index a93b40ea0bad..032a585293af 100644
> --- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> +++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> @@ -287,25 +287,12 @@ static int parse_line(char *line, struct resctrl_schema *s,
>  	return -EINVAL;
>  }
>  
> -static u32 get_config_index(u32 closid, enum resctrl_conf_type type)
> -{
> -	switch (type) {
> -	default:
> -	case CDP_NONE:
> -		return closid;
> -	case CDP_CODE:
> -		return closid * 2 + 1;
> -	case CDP_DATA:
> -		return closid * 2;
> -	}
> -}
> -

...

> --- a/include/linux/resctrl.h
> +++ b/include/linux/resctrl.h
> @@ -384,6 +384,21 @@ void resctrl_arch_mon_event_config_write(void *config_info);
>   */
>  void resctrl_arch_mon_event_config_read(void *config_info);
>  
> +/* For use by arch code to remap resctrl's smaller CDP CLOSID range */
> +static inline u32 resctrl_get_config_index(u32 closid,
> +					   enum resctrl_conf_type type)
> +{
> +	switch (type) {
> +	default:
> +	case CDP_NONE:
> +		return closid;
> +	case CDP_CODE:
> +		return closid * 2 + 1;
> +	case CDP_DATA:
> +		return closid * 2;
> +	}
> +}
> +

Could you please add the motivation for the use of an inline function?

Reinette