linux-kernel - Re: Support generic disabling of all XSAVE features

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Message-ID: <87vao07ncf.fsf@firstfloor.org>
Date:   Mon, 12 Jun 2017 17:17:20 -0700
From:   Andi Kleen <andi@...stfloor.org>
To:     x86@...nel.org
Cc:     linux-kernel@...r.kernel.org
Subject: Re: Support generic disabling of all XSAVE features

Andi Kleen <andi@...stfloor.org> writes:

Any comments on this patchkit? If there are no objections please merge.

-Andi

> For performance testing and debugging it can be useful to disable XSAVE
> features individually. This patchkit hooks up XSAVE with the
> generic clearcpuid=... option, so that disabling a CPUID feature
> automatically disables the respective XSAVE feature.
>
> It also cleans up CPUID dependency management. Currently it's
> possible to generate configurations with cleacpuid that crash.
>
> It replaces an earlier patchkit that did this with special
> case options.
>
> v1:
> Initial post
> v2:
> Work around broken lguest by exporting set_cpu_cap
> Repost with cover letter