linux-kernel - Re: [RFC PATCH 04/10 v2 ] x86/fpu: eager switch PKRU state

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Message-ID: <20180918160419.2zeru6xnufxixcax@linutronix.de>
Date:   Tue, 18 Sep 2018 18:04:20 +0200
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Rik van Riel <riel@...riel.com>, linux-kernel@...r.kernel.org,
        x86@...nel.org, Andy Lutomirski <luto@...nel.org>,
        Radim Krčmář <rkrcmar@...hat.com>,
        kvm@...r.kernel.org, "Jason A. Donenfeld" <Jason@...c4.com>
Subject: Re: [RFC PATCH 04/10 v2 ] x86/fpu: eager switch PKRU state

On 2018-09-18 17:29:52 [+0200], Paolo Bonzini wrote:
> > I don't think it matters what the PKRU state is
> > for kernel threads, since kernel PTEs should not
> > be using protection keys anyway.
> 
> What about copy_from/to_user?

This doesn't work for a kernel thread, does it? I mean they share the
init's MM and never do copy_{from|to}_user.

> Paolo

Sebastian