linux-kernel - Re: [PATCH v2] arm64: spectre: increase parameters that can be used to turn off bhb mitigation individually

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Message-ID: <YxiqsXjQQGe0dNuA@arm.com>
Date:   Wed, 7 Sep 2022 15:29:05 +0100
From:   Catalin Marinas <catalin.marinas@....com>
To:     Liu Song <liusong@...ux.alibaba.com>
Cc:     will@...nel.org, james.morse@....com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] arm64: spectre: increase parameters that can be used
 to turn off bhb mitigation individually

On Fri, Aug 26, 2022 at 07:40:50PM +0800, Liu Song wrote:
> From: Liu Song <liusong@...ux.alibaba.com>
> 
> In our environment, it was found that the mitigation BHB has a great
> impact on the benchmark performance. For example, in the lmbench test,
> the "process fork && exit" test performance drops by 20%.
> So it is necessary to have the ability to turn off the mitigation
> individually through cmdline, thus avoiding having to compile the
> kernel by adjusting the config.
> 
> Signed-off-by: Liu Song <liusong@...ux.alibaba.com>

If people want to disable this mitigation and know what they are doing,
I have no objection:

Acked-by: Catalin Marinas <catalin.marinas@....com>

(I guess that's more like 6.1 material)

-- 
Catalin