linux-kernel - Re: [PATCH v6 19/42] x86/resctrl: Add resctrl_arch_is_evt

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Message-ID: <cc14a8a5-e2d0-4c10-b3b3-d44e061e1a7d@arm.com>
Date: Fri, 28 Feb 2025 19:56:21 +0000
From: James Morse <james.morse@....com>
To: Reinette Chatre <reinette.chatre@...el.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 19/42] x86/resctrl: Add
 resctrl_arch_is_evt_configurable() to abstract BMEC

Hi Reinette,

On 20/02/2025 00:13, Reinette Chatre wrote:
> On 2/7/25 10:18 AM, James Morse wrote:
>> When BMEC is supported the resctrl event can be configured in a number
>> of ways. This depends on architecture support. rdt_get_mon_l3_config()
>> modifies the struct mon_evt and calls mbm_config_rftype_init() to create
>> the files that allow the configuration.
>>
>> Splitting this into separate architecture and filesystem parts would
>> require the struct mon_evt and mbm_config_rftype_init() to be exposed.
>>
>> Instead, add resctrl_arch_is_evt_configurable(), and use this from
>> resctrl_mon_resource_init() to initialise struct mon_evt and call
>> mbm_config_rftype_init().
>> resctrl_arch_is_evt_configurable() calls rdt_cpu_has() so it doesn't
>> obviously benefit from being inlined. Putting it in core.c will allow
>> rdt_cpu_has() to eventually become static.

> Please replace all instances of mbm_config_rftype_init() with 
> resctrl_file_fflags_init().

Fixed, sorry I didn't spot that.


>> diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
>> index 7d14d80b3f94..43a9291988d3 100644
>> --- a/arch/x86/kernel/cpu/resctrl/core.c
>> +++ b/arch/x86/kernel/cpu/resctrl/core.c
>> @@ -831,6 +831,21 @@ bool __init rdt_cpu_has(int flag)
>>  	return ret;
>>  }
>>  
>> +bool __init resctrl_arch_is_evt_configurable(enum resctrl_event_id evt)

> I know resctrl is not consistent in this regard but I think that it would improve
> resctrl quality if new additions follow guidance from Documentation/process/coding-style.rst
> (see section 6.1) Function prototypes) to place storage class attribute
> (__init) before return type.

Done.


Thanks,

James