From mboxrd@z Thu Jan  1 00:00:00 1970
From: Cyrill Gorcunov <gorcunov@gmail.com>
Subject: Re: [PATCH 2/2] kvm tools, vesa: Fix 'ah' access in int10_vesa()
Date: Mon, 6 Jun 2011 12:37:07 +0400
Message-ID: <20110606083707.GA21290@sun>
References: <1307129824-8396-1-git-send-email-penberg@kernel.org>
 <1307129824-8396-2-git-send-email-penberg@kernel.org>
 <4DEC8FC8.8090601@redhat.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Cc: Pekka Enberg <penberg@kernel.org>, kvm@vger.kernel.org,
	Ingo Molnar <mingo@elte.hu>, John Floren <john@jfloren.net>,
	Sasha Levin <levinsasha928@gmail.com>
To: Avi Kivity <avi@redhat.com>
Return-path: <kvm-owner@vger.kernel.org>
Received: from mail-bw0-f46.google.com ([209.85.214.46]:54261 "EHLO
	mail-bw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1756915Ab1FFIhO (ORCPT <rfc822;kvm@vger.kernel.org>);
	Mon, 6 Jun 2011 04:37:14 -0400
Received: by bwz15 with SMTP id 15so3108946bwz.19
        for <kvm@vger.kernel.org>; Mon, 06 Jun 2011 01:37:13 -0700 (PDT)
Content-Disposition: inline
In-Reply-To: <4DEC8FC8.8090601@redhat.com>
Sender: kvm-owner@vger.kernel.org
List-ID: <kvm.vger.kernel.org>

On Mon, Jun 06, 2011 at 11:28:56AM +0300, Avi Kivity wrote:
> On 06/03/2011 10:37 PM, Pekka Enberg wrote:
> >This patch fixes access to 'ah' in int10_vesa() by masking the high bits.
> >
> >@@ -131,7 +131,7 @@ static void int10_vesa(struct int10_args *args)
> >  {
> >  	u8 al;
> >
> >-	al = args->eax;
> >+	al = args->eax&  0xff;
> 
> Isn't this reading %al?  And the high bits are masked by the type of
> the variable?
> 

Type conversion will do the work but having explicit masking is
a way better I believe, at least it makes this code snippet notable.

	Cyrill