linux-kernel - Re: [PATCH 2/7] x86/resctrl: Add SDCIAE feature in the command line options

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Message-ID: <80445b97-e238-4bdb-8435-b8d5de97a2dd@amd.com>
Date: Wed, 18 Sep 2024 09:38:13 -0500
From: "Moger, Babu" <babu.moger@....com>
To: Reinette Chatre <reinette.chatre@...el.com>, corbet@....net,
 tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
 dave.hansen@...ux.intel.com, x86@...nel.org
Cc: fenghua.yu@...el.com, hpa@...or.com, paulmck@...nel.org,
 thuth@...hat.com, xiongwei.song@...driver.com, ardb@...nel.org,
 pawan.kumar.gupta@...ux.intel.com, daniel.sneddon@...ux.intel.com,
 sandipan.das@....com, kai.huang@...el.com, peterz@...radead.org,
 kan.liang@...ux.intel.com, pbonzini@...hat.com, xin3.li@...el.com,
 ebiggers@...gle.com, alexandre.chartre@...cle.com, perry.yuan@....com,
 tan.shaopeng@...itsu.com, james.morse@....com, tony.luck@...el.com,
 maciej.wieczor-retman@...el.com, linux-doc@...r.kernel.org,
 linux-kernel@...r.kernel.org, peternewman@...gle.com, eranian@...gle.com
Subject: Re: [PATCH 2/7] x86/resctrl: Add SDCIAE feature in the command line
 options

Hi Reinette,

On 9/13/24 15:45, Reinette Chatre wrote:
> Hi Babu,
> 
> On 8/16/24 9:16 AM, Babu Moger wrote:
>> Add the command line options to enable or disable the new resctrl feature
>> L3 Smart Data Cache Injection Allocation Enforcement (SDCIAE).
>>
>> Signed-off-by: Babu Moger <babu.moger@....com>
>> ---
>>   Documentation/admin-guide/kernel-parameters.txt | 2 +-
>>   arch/x86/kernel/cpu/resctrl/core.c              | 2 ++
>>   2 files changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/Documentation/admin-guide/kernel-parameters.txt
>> b/Documentation/admin-guide/kernel-parameters.txt
>> index 09126bb8cc9f..63f17d23b8f4 100644
>> --- a/Documentation/admin-guide/kernel-parameters.txt
>> +++ b/Documentation/admin-guide/kernel-parameters.txt
>> @@ -5604,7 +5604,7 @@
>>       rdt=        [HW,X86,RDT]
>>               Turn on/off individual RDT features. List is:
>>               cmt, mbmtotal, mbmlocal, l3cat, l3cdp, l2cat, l2cdp,
>> -            mba, smba, bmec.
>> +            mba, smba, bmec, sdciae.
>>               E.g. to turn on cmt and turn off mba use:
>>                   rdt=cmt,!mba
>>   diff --git a/arch/x86/kernel/cpu/resctrl/core.c
>> b/arch/x86/kernel/cpu/resctrl/core.c
>> index 1930fce9dfe9..c4dfc768ddf5 100644
>> --- a/arch/x86/kernel/cpu/resctrl/core.c
>> +++ b/arch/x86/kernel/cpu/resctrl/core.c
>> @@ -801,6 +801,7 @@ enum {
>>       RDT_FLAG_MBA,
>>       RDT_FLAG_SMBA,
>>       RDT_FLAG_BMEC,
>> +    RDT_FLAG_SDCIAE,
>>   };
>>     #define RDT_OPT(idx, n, f)    \
>> @@ -826,6 +827,7 @@ static struct rdt_options rdt_options[]  __initdata = {
>>       RDT_OPT(RDT_FLAG_MBA,        "mba",    X86_FEATURE_MBA),
>>       RDT_OPT(RDT_FLAG_SMBA,        "smba",    X86_FEATURE_SMBA),
>>       RDT_OPT(RDT_FLAG_BMEC,        "bmec",    X86_FEATURE_BMEC),
>> +    RDT_OPT(RDT_FLAG_SDCIAE,    "sdciae",    X86_FEATURE_SDCIAE),
>>   };
>>   #define NUM_RDT_OPTIONS ARRAY_SIZE(rdt_options)
>>   
> 
> Why is this needed when patch #5 introduces an interface to enable/disable
> this feature after mount?

We have provided option to disable the RDT features on boot. To be
consistent, I have add this feature also to the list.

Yes. Feature can be enabled or disabled after mount.
Thanks
Babu Moger