linux-kernel - Re: [PATCH v2] x86/fpu: Disable BH while while loading FPU registers in __fpu__restore

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Message-ID: <20181119172743.GE14688@zn.tnic>
Date:   Mon, 19 Nov 2018 18:27:43 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Dave Hansen <dave.hansen@...el.com>
Cc:     x86@...nel.org, Ingo Molnar <mingo@...nel.org>,
        linux-kernel@...r.kernel.org, Andy Lutomirski <luto@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        kvm@...r.kernel.org, "Jason A. Donenfeld" <Jason@...c4.com>,
        Rik van Riel <riel@...riel.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>
Subject: Re: [PATCH v2] x86/fpu: Disable BH while while loading FPU registers
 in __fpu__restore_sig()

On Mon, Nov 19, 2018 at 06:11:29PM +0100, Sebastian Andrzej Siewior wrote:
> On 2018-11-19 09:02:45 [-0800], Dave Hansen wrote:
> > On 11/19/18 8:04 AM, Sebastian Andrzej Siewior wrote:
> > > v1…v2: A more verbose commit as message.
> > 
> > I was really hoping for code comments. :)
> 
> I though we agreed to make those in the larger series because those
> comments in __fpu__restore_sig() would be removed anyway (as part of the
> series).

Also, over local_bh_disable() does not really fit as this is generic
code and Sebastian said ARM does the whole thing a bit differently, for
one.

We probably should put that comment somewhere prominent in
arch/x86/kernel/fpu/core.c or similar - somewhere people poking at FPU
stuff will see it.

-- 
Regards/Gruss,
    Boris.

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