linux-kernel - Re: [PATCH v5 22/40] x86/resctrl: Move mbm_cfg_mask to struct rdt

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Message-ID: <adbe208d-7a16-46c1-88ec-ceb99122f84c@intel.com>
Date: Wed, 23 Oct 2024 15:42:05 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: James Morse <james.morse@....com>, <x86@...nel.org>,
	<linux-kernel@...r.kernel.org>
CC: Fenghua Yu <fenghua.yu@...el.com>, 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>, Shaopeng Tan
	<tan.shaopeng@...fujitsu.com>
Subject: Re: [PATCH v5 22/40] x86/resctrl: Move mbm_cfg_mask to struct
 rdt_resource

Hi James,

On 10/4/24 11:03 AM, James Morse wrote:
> The mbm_cfg_mask field lists the bits that user-space can set when
> configuring an event. This value is output via the last_cmd_status
> file.
> 
> Once the filesystem parts of resctrl are moved to live in /fs/, the
> struct rdt_hw_resource is inaccessible to the filesystem code. Because
> this value is output to user-space, it has to be accessible to the
> filesystem code.
> 
> Move it to struct rdt_resource.
> 

fyi:
https://lore.kernel.org/all/fc424d4bee8ac9887703fecbaad26dba3c633f72.1728495588.git.babu.moger@amd.com/

> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
> index 6b076216911c..92a94939cf93 100644
> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> @@ -415,8 +415,6 @@ struct msr_param {
>   * @msr_update:		Function pointer to update QOS MSRs
>   * @mon_scale:		cqm counter * mon_scale = occupancy in bytes
>   * @mbm_width:		Monitor width, to detect and correct for overflow.
> - * @mbm_cfg_mask:	Bandwidth sources that can be tracked when Bandwidth
> - *			Monitoring Event Configuration (BMEC) is supported.
>   * @cdp_enabled:	CDP state of this resource
>   *
>   * Members of this structure are either private to the architecture
> @@ -430,7 +428,6 @@ struct rdt_hw_resource {
>  	void			(*msr_update)(struct msr_param *m);
>  	unsigned int		mon_scale;
>  	unsigned int		mbm_width;
> -	unsigned int		mbm_cfg_mask;
>  	bool			cdp_enabled;
>  };
>  

...

> diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
> index 0072c2e5947f..84588ab1994d 100644
> --- a/include/linux/resctrl.h
> +++ b/include/linux/resctrl.h
> @@ -218,6 +218,8 @@ enum resctrl_schema_fmt {
>   * @name:		Name to use in "schemata" file.
>   * @schema_fmt:	Which format string and parser is used for this schema.
>   * @evt_list:		List of monitoring events
> + * @mbm_cfg_mask:	Bandwidth sources that can be tracked when Bandwidth
> + *			Monitoring Event Configuration (BMEC) is supported.

Making this arch specific feature something all arch can support is probably the
right time to remove the AMD marketing name. Maybe just:

			Bandwidth sources that can be tracked when memory bandwidth
			monitoring events can be configured.

Please feel free to improve.
	
Reinette