From: Mark McLoughlin <markmc@redhat.com> To: Scott Tsai <scottt.tw@gmail.com> Cc: Dustin Kirkland <kirkland@canonical.com>, qemu-devel <qemu-devel@nongnu.org>, kvm <kvm@vger.kernel.org>, Anthony Liguori <anthony@codemonkey.ws> Subject: Re: [Qemu-devel] qemu-kvm-0.11 regression, crashes on older guests with virtio network Date: Thu, 29 Oct 2009 12:16:06 +0000 [thread overview] Message-ID: <1256818566.10825.58.camel@blaa> (raw) In-Reply-To: <1256815818-sup-7805@xpc65.scottt> On Thu, 2009-10-29 at 20:00 +0800, Scott Tsai wrote: > Excerpts from Mark McLoughlin's message of Thu Oct 29 17:16:43 +0800 2009: > > Assuming this is something like the virtio-net in 2.6.26, there was no > > receivable buffers support so (as Scott points out) it must be that > > we've read a packet from the tap device which is >1514 bytes (or >1524 > > bytes with IFF_VNET_HDR) but the guest has not supplied buffers which > > are large enough to take it > > > One thing to check is that the tap device is being initialized by > > qemu-kvm using TUNSETOFFLOAD with either zero or TUN_F_CSUM - i.e. GSO > > should not be enabled, because the guest cannot handle large GSO packets > > > Another possibility is that the MTU on the bridge in the host is too > > large and that's what's causing the large packets to be sent > > Using Dustin's image, I see: > virtio_net_set_features(features: 0x00000930) Hmm - 0x930 doesn't seem right. Is that 930 decimal, 0x3a2 hex? > tap_set_offload(csum: 1, tso4: 1, tso6: 1, ecn: 1) > being called and get an mtu of 1500 on virbr0 using his birdge.sh script. > > virtio_net_receive2 was trying to transfer a 1534 byte packet (1524 'size' + 10 'virtio_net_hdr') > and the guest only had 1524 bytes of space in its input descriptors. Okay, that sounds like a bug in Dustin's version of the guest virtio-net driver - if it is only supplying 1524 byte buffers, it should not be saying it supports the VIRTIO_NET_F_GUEST_TSO4 feature Cheers, Mark.
WARNING: multiple messages have this Message-ID (diff)
From: Mark McLoughlin <markmc@redhat.com> To: Scott Tsai <scottt.tw@gmail.com> Cc: qemu-devel <qemu-devel@nongnu.org>, kvm <kvm@vger.kernel.org>, Dustin Kirkland <kirkland@canonical.com> Subject: Re: [Qemu-devel] qemu-kvm-0.11 regression, crashes on older guests with virtio network Date: Thu, 29 Oct 2009 12:16:06 +0000 [thread overview] Message-ID: <1256818566.10825.58.camel@blaa> (raw) In-Reply-To: <1256815818-sup-7805@xpc65.scottt> On Thu, 2009-10-29 at 20:00 +0800, Scott Tsai wrote: > Excerpts from Mark McLoughlin's message of Thu Oct 29 17:16:43 +0800 2009: > > Assuming this is something like the virtio-net in 2.6.26, there was no > > receivable buffers support so (as Scott points out) it must be that > > we've read a packet from the tap device which is >1514 bytes (or >1524 > > bytes with IFF_VNET_HDR) but the guest has not supplied buffers which > > are large enough to take it > > > One thing to check is that the tap device is being initialized by > > qemu-kvm using TUNSETOFFLOAD with either zero or TUN_F_CSUM - i.e. GSO > > should not be enabled, because the guest cannot handle large GSO packets > > > Another possibility is that the MTU on the bridge in the host is too > > large and that's what's causing the large packets to be sent > > Using Dustin's image, I see: > virtio_net_set_features(features: 0x00000930) Hmm - 0x930 doesn't seem right. Is that 930 decimal, 0x3a2 hex? > tap_set_offload(csum: 1, tso4: 1, tso6: 1, ecn: 1) > being called and get an mtu of 1500 on virbr0 using his birdge.sh script. > > virtio_net_receive2 was trying to transfer a 1534 byte packet (1524 'size' + 10 'virtio_net_hdr') > and the guest only had 1524 bytes of space in its input descriptors. Okay, that sounds like a bug in Dustin's version of the guest virtio-net driver - if it is only supplying 1524 byte buffers, it should not be saying it supports the VIRTIO_NET_F_GUEST_TSO4 feature Cheers, Mark.
next prev parent reply other threads:[~2009-10-29 12:18 UTC|newest] Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top 2009-10-28 19:22 qemu-kvm-0.11 regression, crashes on older guests with virtio network Dustin Kirkland 2009-10-28 19:22 ` [Qemu-devel] " Dustin Kirkland 2009-10-28 19:29 ` Dustin Kirkland 2009-10-28 19:29 ` [Qemu-devel] " Dustin Kirkland 2009-10-29 3:12 ` [Qemu-devel] " Scott Tsai 2009-10-29 3:12 ` Scott Tsai 2009-10-29 9:16 ` Mark McLoughlin 2009-10-29 9:16 ` Mark McLoughlin 2009-10-29 12:00 ` Scott Tsai 2009-10-29 12:00 ` Scott Tsai 2009-10-29 12:16 ` Mark McLoughlin [this message] 2009-10-29 12:16 ` Mark McLoughlin 2009-10-29 12:21 ` Scott Tsai 2009-10-29 12:21 ` Scott Tsai 2009-10-29 14:11 ` Anthony Liguori 2009-10-29 14:11 ` Anthony Liguori 2009-10-29 14:25 ` Mark McLoughlin 2009-10-29 14:25 ` Mark McLoughlin 2009-10-29 14:34 ` Dustin Kirkland 2009-10-29 14:34 ` Dustin Kirkland 2009-10-29 14:46 ` Dustin Kirkland 2009-10-29 14:46 ` Dustin Kirkland 2009-10-29 14:50 ` Mark McLoughlin 2009-10-29 14:50 ` Mark McLoughlin 2009-10-29 14:39 ` Anthony Liguori 2009-10-29 14:39 ` Anthony Liguori 2009-10-29 14:48 ` Mark McLoughlin 2009-10-29 14:48 ` Mark McLoughlin 2009-10-29 15:01 ` Dustin Kirkland 2009-10-29 15:01 ` Dustin Kirkland 2009-10-29 15:01 ` Mark McLoughlin 2009-10-29 15:01 ` Mark McLoughlin 2009-10-29 15:13 ` Dustin Kirkland 2009-10-29 15:13 ` Dustin Kirkland 2009-10-29 15:15 ` Mark McLoughlin 2009-10-29 15:15 ` Mark McLoughlin 2009-10-29 15:34 ` [PATCH] whitelist host virtio networking features [was Re: qemu-kvm-0.11 regression, crashes on older ...] Dustin Kirkland 2009-10-29 15:34 ` [Qemu-devel] " Dustin Kirkland 2009-10-30 21:15 ` Dustin Kirkland 2009-10-30 21:15 ` [Qemu-devel] " Dustin Kirkland 2009-11-02 14:38 ` Mark McLoughlin 2009-11-02 14:38 ` [Qemu-devel] " Mark McLoughlin 2009-11-02 15:42 ` Anthony Liguori 2009-11-02 15:42 ` [Qemu-devel] " Anthony Liguori 2009-11-02 15:52 ` Jamie Lokier 2009-11-02 18:20 ` Michael Tokarev 2009-11-02 18:20 ` Michael Tokarev 2009-11-02 19:39 ` Jamie Lokier 2009-11-02 19:39 ` Jamie Lokier 2009-11-02 18:55 ` Anthony Liguori 2009-11-02 19:25 ` Dustin Kirkland 2009-11-02 19:25 ` Dustin Kirkland 2009-11-02 20:50 ` Anthony Liguori 2009-11-02 20:50 ` Anthony Liguori 2009-11-05 5:06 ` Jamie Lokier 2009-11-05 5:06 ` Jamie Lokier 2009-11-02 16:58 ` Dustin Kirkland 2009-11-02 16:58 ` [Qemu-devel] " Dustin Kirkland 2009-10-29 14:39 ` [Qemu-devel] qemu-kvm-0.11 regression, crashes on older guests with virtio network Dustin Kirkland 2009-10-29 14:39 ` Dustin Kirkland 2009-10-29 23:22 ` Scott Tsai 2009-10-29 23:22 ` Scott Tsai 2009-10-29 12:23 ` Michael S. Tsirkin 2009-10-29 12:23 ` [Qemu-devel] " Michael S. Tsirkin 2009-10-29 14:38 ` Avi Kivity 2009-10-29 14:38 ` [Qemu-devel] " Avi Kivity 2009-10-29 15:03 ` Michael S. Tsirkin 2009-10-29 15:03 ` [Qemu-devel] " Michael S. Tsirkin 2009-10-29 14:43 ` [Qemu-devel] " Dustin Kirkland 2009-10-29 14:43 ` Dustin Kirkland
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