linux-kernel - Re: [PATCH v7 07/49] x86/resctrl: Add max_bw to struct resctrl

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <8a0dcd23-2458-4b60-a90a-f9bfab00bc8e@nvidia.com>
Date: Thu, 6 Mar 2025 13:02:43 -0800
From: Fenghua Yu <fenghuay@...dia.com>
To: James Morse <james.morse@....com>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Cc: Reinette Chatre <reinette.chatre@...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>, 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 v7 07/49] x86/resctrl: Add max_bw to struct resctrl_membw


On 2/28/25 11:58, James Morse wrote:
> __rdt_get_mem_config_amd() and __get_mem_config_intel() both use
> the default_ctrl property as a maximum value. This is because the
> MBA schema works differently between these platforms. Doing this
> complicates determining whether the default_ctrl property belongs
> to the arch code, or can be derived from the schema format.
>
> Deriving the maximum or default value from the schema format would
> avoid the architecture code having to tell resctrl such obvious
> things as the maximum percentage is 100, and the maximum bitmap
> is all ones.
>
> Maximum bandwidth is always going to vary per platform. Add
> max_bw as a special case. This is currently used for the maximum
> MBA percentage on Intel platforms, but can be removed from the
> architecture code if 'percentage' becomes a schema format resctrl
> supports directly.
>
> This value isn't needed for other schema formats.
>
> This will allow the default_ctrl to be generated from the schema
> properties when it is needed.
>
> 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>
> Reviewed-by: Reinette Chatre <reinette.chatre@...el.com>

Reviewed-by: Fenghua Yu <fenghuay@...dia.com>


Thanks.


-Fenghua