linux-kernel - Re: [v2 1/1] x86/cpufeatures: Implement Predictive Store Forwarding control.

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Message-ID: <4511e1d1-9ca9-c434-9a3f-322e54ffbe73@amd.com>
Date:   Thu, 22 Apr 2021 16:23:14 -0500
From:   "Saripalli, RK" <rsaripal@....com>
To:     Randy Dunlap <rdunlap@...radead.org>, linux-kernel@...r.kernel.org,
        x86@...nel.org, tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
        hpa@...or.com, Jonathan Corbet <corbet@....net>
Cc:     bsd@...hat.com
Subject: Re: [v2 1/1] x86/cpufeatures: Implement Predictive Store Forwarding
 control.



On 4/22/2021 3:46 PM, Randy Dunlap wrote:
> On 4/22/21 12:32 PM, Saripalli, RK wrote:
>>
>>
>> On 4/22/2021 12:49 PM, Randy Dunlap wrote:
>>> On 4/22/21 10:10 AM, Ramakrishna Saripalli wrote:
>>>> From: Ramakrishna Saripalli <rk.saripalli@....com>
>>>>
>>>> ====================
>>>> Signed-off-by: Ramakrishna Saripalli<rk.saripalli@....com>
>>>> ---
>>>>  .../admin-guide/kernel-parameters.txt         |  5 +++++
>>>>  arch/x86/include/asm/cpufeatures.h            |  1 +
>>>>  arch/x86/include/asm/msr-index.h              |  2 ++
>>>>  arch/x86/kernel/cpu/amd.c                     | 19 +++++++++++++++++++
>>>>  4 files changed, 27 insertions(+)
>>>
>>> as from v1:
>>
>> Randy, could you clarify your comments please?. Is there something here I need to change/clarify/fix?
>>
> 
> Only that I had made these same comments (below)
> in v1 of the patch.

Yes I see them. I missed them. I will include them in the next patch release (batch them with other changes)
> 
> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Flkml%2F4c688fc7-67df-3187-54b2-bf20e510fb39%40infradead.org%2F&amp;data=04%7C01%7Crk.saripalli%40amd.com%7Cfd08fbf7545d4c27c4cd08d905cfde95%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637547212629713144%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=hlGLgbZobkqXf3aBdMhSFC6Lg8nBLg1ssjHJDoyzI9s%3D&amp;reserved=0
> 
>>>
>>>> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
>>>> index 04545725f187..58f6bd02385b 100644
>>>> --- a/Documentation/admin-guide/kernel-parameters.txt
>>>> +++ b/Documentation/admin-guide/kernel-parameters.txt
>>>> @@ -3940,6 +3940,11 @@
>>>>  			Format: {"off"}
>>>>  			Disable Hardware Transactional Memory
>>>>  
>>>> +	predict_store_fwd	[X86] This option controls PSF mitigation
>>>
>>> 	predict_store_fwd=	...
>>>
>>
>> OK
>>
>>>> +			off - Turns on PSF mitigation.
>>>> +			on  - Turns off PSF mitigation.
>>>> +			default : on.
>>>
>>> 			default: on.
>>>
>>
>> OK
>>
>>>> +
>>>>  	preempt=	[KNL]
>>>>  			Select preemption mode if you have CONFIG_PREEMPT_DYNAMIC
>>>>  			none - Limited to cond_resched() calls
> 

thanks,
RK