From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Matt Carlson" Subject: Re: TG3, kvm, ipv6 & tso data corruption bug? Date: Wed, 28 Oct 2009 09:32:26 -0700 Message-ID: <20091028163226.GA8556@xw6200.broadcom.net> References: <4AE8595F.1080404@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: "netdev@vger.kernel.org" , "Linux kernel Mailing List" , "Matthew Carlson" , "Michael Chan" , "KVM list" To: "Rik van Riel" Return-path: In-Reply-To: <4AE8595F.1080404@redhat.com> Content-Disposition: inline Sender: kvm-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Wed, Oct 28, 2009 at 07:46:55AM -0700, Rik van Riel wrote: > I have been tracking down what I thought was a KVM related network > issue for a while, however it appears it could be a hardware issue. > > The symptom is that data in network packets gets corrupted, before > the checksum is calculated. This means the remote host can get > corrupted data, with no way to calculate it (except application > level checksums). Luckily ssh has such checksums, so my rsync over > ssh backup script discovered this issue. > > On a very regular basis, I got this message from ssh: > > Corrupted MAC on input. > > I have played around a bit and narrowed it down to the following: > > ipv4 => no problem > ipv6 w/o tso => no problem > ipv6 with tso => occasional data corruption > > Disabling tso with ethtool -K eth0 tso off makes the problem stop. > > I am running Fedora 12's 2.6.31.1-56.fc12.x86_64 kernel, with the > following hardware: > > 05:00.0 Ethernet controller: Broadcom Corporation NetXtreme BCM5761 > Gigabit Ethernet PCIe (rev 10) > > I do not know enough about the network layer to know whether this is > fixable in software or whether TSO offloading for ipv6 should just > be disabled on this model. This problem sounds familiar. There are chip bugs in this area, but as far as I know, they should have been worked around. Let me see if this is indeed the same bug resurfacing.