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

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Date:   Thu, 22 Apr 2021 13:46:40 -0700
From:   Randy Dunlap <rdunlap@...radead.org>
To:     "Saripalli, RK" <rsaripal@....com>, 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 4/22/21 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.

https://lore.kernel.org/lkml/4c688fc7-67df-3187-54b2-bf20e510fb39@infradead.org/

>>
>>> 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

-- 
~Randy