linux-kernel - Re: [patch 09/31] x86/fpu: Do not inherit FPU context for CLONE

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Message-ID: <YWWzgO9Vn6XlNsLP@zn.tnic>
Date:   Tue, 12 Oct 2021 18:10:40 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
        "Chang S. Bae" <chang.seok.bae@...el.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Arjan van de Ven <arjan@...ux.intel.com>,
        kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>
Subject: Re: [patch 09/31] x86/fpu: Do not inherit FPU context for
 CLONE_THREAD

On Tue, Oct 12, 2021 at 02:00:11AM +0200, Thomas Gleixner wrote:
> CLONE_THREAD does not have the guarantee of a true fork to inherit all
> state. Especially the FPU state is meaningless for CLONE_THREAD.
> 
> Just wipe out the minimal required state so restore on return to user space
> let's the thread start with a clean FPU.

This sentence reads weird, needs massaging.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette