From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38601) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bi0sy-0003xW-GB for qemu-devel@nongnu.org; Thu, 08 Sep 2016 11:05:08 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bi0st-0003GU-5Y for qemu-devel@nongnu.org; Thu, 08 Sep 2016 11:05:03 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:39248) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bi0ss-0003GO-S2 for qemu-devel@nongnu.org; Thu, 08 Sep 2016 11:04:59 -0400 Received: from pps.filterd (m0098396.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.17/8.16.0.17) with SMTP id u88F37i5089055 for ; Thu, 8 Sep 2016 11:04:58 -0400 Received: from e06smtp06.uk.ibm.com (e06smtp06.uk.ibm.com [195.75.94.102]) by mx0a-001b2d01.pphosted.com with ESMTP id 25b2qvj0bk-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Thu, 08 Sep 2016 11:04:57 -0400 Received: from localhost by e06smtp06.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 8 Sep 2016 16:04:54 +0100 Received: from b06cxnps4075.portsmouth.uk.ibm.com (d06relay12.portsmouth.uk.ibm.com [9.149.109.197]) by d06dlp03.portsmouth.uk.ibm.com (Postfix) with ESMTP id 70EC31B08061 for ; Thu, 8 Sep 2016 16:06:36 +0100 (BST) Received: from d06av02.portsmouth.uk.ibm.com (d06av02.portsmouth.uk.ibm.com [9.149.37.228]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u88F4owr3604748 for ; Thu, 8 Sep 2016 15:04:50 GMT Received: from d06av02.portsmouth.uk.ibm.com (localhost [127.0.0.1]) by d06av02.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id u88F4n8t012714 for ; Thu, 8 Sep 2016 09:04:49 -0600 Date: Thu, 8 Sep 2016 17:04:47 +0200 From: Cornelia Huck In-Reply-To: <20160908175237-mutt-send-email-mst@kernel.org> References: <147326875705.8546.11347276277137015855.stgit@bahia.lan> <147326876478.8546.16045138068342092499.stgit@bahia.lan> <20160908105926.0d968e64.cornelia.huck@de.ibm.com> <20160908111216.12a1b562@bahia> <20160908175237-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Message-Id: <20160908170447.2d864945.cornelia.huck@de.ibm.com> Subject: Re: [Qemu-devel] [PATCH 1/2] virtio-9p: print error message and exit instead of BUG_ON() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: Greg Kurz , qemu-devel@nongnu.org, "Aneesh Kumar K.V" On Thu, 8 Sep 2016 18:00:28 +0300 "Michael S. Tsirkin" wrote: > On Thu, Sep 08, 2016 at 11:12:16AM +0200, Greg Kurz wrote: > > On Thu, 8 Sep 2016 10:59:26 +0200 > > Cornelia Huck wrote: > > > > > On Wed, 07 Sep 2016 19:19:24 +0200 > > > Greg Kurz wrote: > > > > > > > Calling assert() really makes sense when hitting a genuine bug, which calls > > > > for a fix in QEMU. However, when something goes wrong because the guest > > > > sends a malformed message, it is better to write down a more meaningul > > > > error message and exit. > > > > > > > > Signed-off-by: Greg Kurz > > > > --- > > > > hw/9pfs/virtio-9p-device.c | 20 ++++++++++++++++++-- > > > > 1 file changed, 18 insertions(+), 2 deletions(-) > > > > > > While this is an improvement over the current state, I don't think the > > > guest should be able to kill qemu just by doing something stupid. > > > > > > > Hi Connie, > > > > I'm glad you're pointing this out... this was also my impression, but > > since there are a bunch of sanity checks in the virtio code that cause > > QEMU to exit (even recently added like 1e7aed70144b), I did not dare > > stand up :) > > It's true that it's broken in many places but we should just > fix them all. > > > A separate question is how to log such hardware/guest bugs generally. > People already complained about disk filling up because of us printing > errors on each such bug. Maybe print each message only N times, and > then set a flag to skip the log until management tells us to restart > logging again. I'd expect to get the message just once per device if we set the device to broken (unless the guess continuously resets it again...) Do we have a generic print/log ratelimit infrastructure in qemu?