linux-kernel - Re: [PATCH v5] KVM: x86: avoid large stack allocations in em

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Message-ID: <20170602021014.4sdvqe6mgqa4cq46@lostoracle.net>
Date:   Thu, 1 Jun 2017 19:10:14 -0700
From:   Nick Desaulniers <nick.desaulniers@...il.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Radim Krčmář <rkrcmar@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5] KVM: x86: avoid large stack allocations in em_fxrstor

On Thu, Jun 01, 2017 at 09:36:18AM +0200, Paolo Bonzini wrote:
> On 01/06/2017 03:05, Nick Desaulniers wrote:
> > On Wed, May 31, 2017 at 07:01:29AM -0400, Paolo Bonzini wrote:
> >>> +		size = offsetof(struct fxregs_state, xmm_space[16]);
> >> This still has the same issue (it should be multiplied by 4).
> > 
> > I'm still misunderstanding the math here.
> > 
> > Why multiplied by four, in this case? 8 * 16 / 4 is used in other cases.
> 
> *16/4 is the same as *4. :)

I meant the use of an expression full of literals rather than either a
single literal or an expression formed from well named variables seemed
kind of like a code smell, but w/e.  Patch inbound.