linux-kernel - Re: [PATCH v6 06/42] x86/resctrl: Remove data

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: <64d0552f-0015-496f-85d8-5a0b68cc69e0@intel.com>
Date: Wed, 19 Feb 2025 13:56:27 -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 06/42] x86/resctrl: Remove data_width and the tabular
 format

Hi James,

On 2/7/25 10:17 AM, James Morse wrote:
> The resctrl architecture code provides a data_width for the controls of
> each resource. This is used to zero pad all control values in the schemata
> file so they appear in columns. The same is done with the resource names
> to complete the visual effect. e.g.
> | SMBA:0=2048
> |   L3:0=00ff
> 
> AMD platforms discover their maximum bandwidth for the MB resource from
> firmware, but hard-code the data_width to 4. If the maximum bandwidth
> requires more digits - the tabular format is silently broken.
> This is also broken when the mba_MBps mount option is used as the
> field width isn't updated. If new schema are added resctrl will need
> to be able to determine the maximum width. The benefit of this
> pretty-printing is questionable.
> 
> Instead of handling runtime discovery of the data_width for AMD platforms,
> remove the feature. These fields are always zero padded so should be
> harmless to remove if the whole field has been treated as a number.
> In the above example, this would now look like this:
> | SMBA:0=2048
> |   L3:0=ff
> 
> Signed-off-by: James Morse <james.morse@....com>
> 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>

Reinette