linux-kernel - Re: [PATCH v6 18/22] x86/resctrl: Report "Unassigned" for MBM events in ABMC mode

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: <bac86fa6-bfb2-46fc-a279-c6a263c00058@intel.com>
Date: Fri, 16 Aug 2024 14:42:32 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: Babu Moger <babu.moger@....com>, <corbet@....net>, <fenghua.yu@...el.com>,
	<tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>,
	<dave.hansen@...ux.intel.com>
CC: <x86@...nel.org>, <hpa@...or.com>, <paulmck@...nel.org>,
	<rdunlap@...radead.org>, <tj@...nel.org>, <peterz@...radead.org>,
	<yanjiewtw@...il.com>, <kim.phillips@....com>, <lukas.bulwahn@...il.com>,
	<seanjc@...gle.com>, <jmattson@...gle.com>, <leitao@...ian.org>,
	<jpoimboe@...nel.org>, <rick.p.edgecombe@...el.com>,
	<kirill.shutemov@...ux.intel.com>, <jithu.joseph@...el.com>,
	<kai.huang@...el.com>, <kan.liang@...ux.intel.com>,
	<daniel.sneddon@...ux.intel.com>, <pbonzini@...hat.com>,
	<sandipan.das@....com>, <ilpo.jarvinen@...ux.intel.com>,
	<peternewman@...gle.com>, <maciej.wieczor-retman@...el.com>,
	<linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<eranian@...gle.com>, <james.morse@....com>
Subject: Re: [PATCH v6 18/22] x86/resctrl: Report "Unassigned" for MBM events
 in ABMC mode

Hi Babu,

On 8/6/24 3:00 PM, Babu Moger wrote:
> In ABMC mode, the hardware counter should be assigned to read the MBM
> events.
> 
> Report "Unassigned" in case the user attempts to read the events without
> assigning the counter.
> 
> Signed-off-by: Babu Moger <babu.moger@....com>
> ---
> v6: Added more explaination in the resctrl.rst
>      Added checks to detect "Unassigned" before reading RMID.
> 
> v5: New patch.
> ---
>   Documentation/arch/x86/resctrl.rst        | 11 +++++++++++
>   arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 13 ++++++++++++-
>   2 files changed, 23 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
> index fe9f10766c4f..aea440ee6107 100644
> --- a/Documentation/arch/x86/resctrl.rst
> +++ b/Documentation/arch/x86/resctrl.rst
> @@ -294,6 +294,17 @@ with the following files:
>   "num_mbm_cntrs":
>   	The number of monitoring counters available for assignment.
>   
> +	Resctrl subsystem provides the interface to count maximum of two
> +	MBM events per group, from a combination of total and local events.
> +	Keeping the current interface, users can assign a maximum of two
> +	monitoring counters per group. User will also have the option to
> +	enable only one counter to the group.
> +
> +	With limited number of counters, system can run out of assignable counters.
> +	In mbm_cntr_assign mode, the MBM event counters will return "Unassigned" if
> +	the counter is not assigned to the event when read. Users need to assign a
> +	counter manually to read the events.

This seems more appropriate for the "mon_data" section.

Reinette