linux-kernel - Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission

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Message-ID: <20180619183847.GC169030@google.com>
Date:   Tue, 19 Jun 2018 11:38:47 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Nick Desaulniers <ndesaulniers@...gle.com>, joe@...ches.com,
        rkrcmar@...hat.com, Thomas Gleixner <tglx@...utronix.de>,
        hpa@...or.com, x86@...nel.org, kvm@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in
 update_permission_bitmask()

On Tue, Jun 19, 2018 at 07:13:41PM +0200, Paolo Bonzini wrote:
> On 19/06/2018 19:08, Nick Desaulniers wrote:
> >> This one really makes the code uglier though, so I'm not really inclined
> >> to applying the patch.
> > Note that of the three variables (w, u, x), only u is used later on.
> > What about declaring them as negated with the cast, that way there's
> > no cast in a ternary?
> 
> I still find it inferior, but I guess it's at least acceptable.  I
> prefer not_{x,w,u} though. :)

Thanks Nick and Paolo for the suggestions, I'll sent an updated
version soon.