linux-kernel - Re: [PATCH 4/4] x86/speculation: Add PSF mitigation kernel parameters

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Date:   Wed, 21 Apr 2021 09:04:30 -0700
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Ramakrishna Saripalli <rsaripal@....com>,
        linux-kernel@...r.kernel.org, x86@...nel.org, tglx@...utronix.de,
        mingo@...hat.com, bp@...en8.de, Jonathan Corbet <corbet@....net>
Cc:     bsd@...hat.com
Subject: Re: [PATCH 4/4] x86/speculation: Add PSF mitigation kernel parameters

Hi,

On 4/21/21 2:01 AM, Ramakrishna Saripalli wrote:
> From: Ramakrishna Saripalli <rk.saripalli@....com>
> 
> PSF mitigation introduces a new kernel parameter called
> 	predict_store_fwd.
> 
> Signed-off-by: Ramakrishna Saripalli<rk.saripalli@....com>
> ---
>  Documentation/admin-guide/kernel-parameters.txt | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> 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
> +			off - Turns on PSF mitigation.
> +			on  - Turns off PSF mitigation.
> +			default : on.

This should be formatted more like:

+	predict_store_fwd=	[X86] This option controls PSF mitigation
+			off - Turns on PSF mitigation.
+			on  - Turns off PSF mitigation.
+			default: on.

But why does "off" turn it on and "on" turn it off?


> +
>  	preempt=	[KNL]
>  			Select preemption mode if you have CONFIG_PREEMPT_DYNAMIC
>  			none - Limited to cond_resched() calls
> 

thanks.
-- 
~Randy