From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:37132)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <mst@redhat.com>) id 1V8VyN-0002ph-6W
	for qemu-devel@nongnu.org; Sun, 11 Aug 2013 09:46:23 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <mst@redhat.com>) id 1V8VyI-0005FK-EO
	for qemu-devel@nongnu.org; Sun, 11 Aug 2013 09:46:19 -0400
Received: from mx1.redhat.com ([209.132.183.28]:5623)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <mst@redhat.com>) id 1V8VyI-0005FD-5c
	for qemu-devel@nongnu.org; Sun, 11 Aug 2013 09:46:14 -0400
Date: Sun, 11 Aug 2013 16:47:40 +0300
From: "Michael S. Tsirkin" <mst@redhat.com>
Message-ID: <20130811134740.GC15442@redhat.com>
References: <1374853288-9912-1-git-send-email-peter.maydell@linaro.org>
	<CAFEAcA-fJTPCLEk=yC7zQXxB+4uRjpH_pZEhKC=FpKc8V68WLA@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CAFEAcA-fJTPCLEk=yC7zQXxB+4uRjpH_pZEhKC=FpKc8V68WLA@mail.gmail.com>
Subject: Re: [Qemu-devel] [PATCH v2 for-1.6 0/2] virtio-mmio: fixes to
 QueueNum, QueueNumMax
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: Anthony Liguori <aliguori@us.ibm.com>, patches@linaro.org, qemu-devel@nongnu.org, kvmarm@lists.cs.columbia.edu

On Fri, Aug 09, 2013 at 04:47:40PM +0100, Peter Maydell wrote:
> On 26 July 2013 16:41, Peter Maydell <peter.maydell@linaro.org> wrote:
> > These patches fix a couple of bugs in virtio-mmio's
> > handling of the registers that deal with the queue size:
> >
> >  * as mst points out, letting the guest flip a queue between
> >    "exists" and "doesn't exist" is a bad idea
> >  * QueueNumMax wasn't reading the correct value for nonexistent
> >    queues
> >
> > This doesn't include any change to the behaviour of queuesize
> > on reset (discussed in other thread); the current behaviour is
> > not a problem for well-behaved guests, and safe in the face
> > of badly-behaved guests, and currently improving the reset
> > behaviour is blocked by an unrelated bug.
> >
> > v1->v2: changes as per mst review:
> >  * avoid explicit "== 0" comparisons
> >  * avoid unnecessary parens round comparison ops
> >  * do the "don't flip between existent and nonexistent" check
> >    with "!!num != !!oldnum" (and add a comment noting why we're
> >    doing this check)
> >
> > Peter Maydell (2):
> >   hw/virtio/virtio: Don't allow guests to add/remove queues
> >   hw/virtio/virtio-mmio: Make QueueNumMax read 0 for unavailable queues
> 
> These didn't make it into 1.6, but in the absence of any
> review comments I'm putting them into arm-devs for post-1.6.
> 
> thanks
> -- PMM

I'd say these are important bugfixes, should be OK for 1.6 still.