Bug 606264 - Ping caused guest abnormally quit after changing virtio_nic MTU
Summary: Ping caused guest abnormally quit after changing virtio_nic MTU
Keywords:
Status: CLOSED DUPLICATE of bug 610343
Alias: None
Product: Red Hat Enterprise Linux 5
Classification: Red Hat
Component: kvm
Version: 5.6
Hardware: All
OS: Linux
medium
medium
Target Milestone: rc
: ---
Assignee: Michael S. Tsirkin
QA Contact: Virtualization Bugs
URL:
Whiteboard:
Depends On:
Blocks: Rhel5KvmTier2
TreeView+ depends on / blocked
 
Reported: 2010-06-21 09:32 UTC by Amos Kong
Modified: 2015-05-25 00:05 UTC (History)
4 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Environment:
Last Closed: 2010-09-12 13:00:20 UTC


Attachments (Terms of Use)

Description Amos Kong 2010-06-21 09:32:30 UTC
Description of problem:
I booted up a guest with virtio nic, change the MTU of guest nic and tap device
to 65520(max MTU of virtio nic), and added an arp entry on host, then ping
guest from host, but guest abnormally quit. Qemu outputted : "virtio-net truncating packet"

# ping $guest_ip -I virtio_0_6001 -s 65492 -M do
PING 10.66.84.205 (10.66.84.205) from 10.66.85.217 virtio_0_6001: 65492(65520) bytes of data.
ping: sendmsg: No such device
ping: sendmsg: No such device
ping: sendmsg: No such device
ping: sendmsg: No such device
ping: sendmsg: No such device
ping: sendmsg: No such device


Version-Release number of selected component (if applicable):
host kernel: 2.6.18-203.el5
guest kernel: 2.6.9-89.28.ELsmp
# rpm -qa |grep kvm
etherboot-zroms-kvm-5.4.4-13.el5
kvm-qemu-img-83-183.el5
kmod-kvm-83-183.el5
kvm-83-183.el5
kvm-tools-83-183.el5
kvm-debuginfo-83-183.el5

How reproducible:
100%

Steps to Reproduce:
1. Boot up a rhel4 guest with virtio nic
2. Change MTU of guest nic and $tap
guest)# ifconfig eth0 mtu 65520
host)# ifconfig $tap mut 65520
3. Add a arp entry on host
# arp -s $guest_ip $guest_mac -i $tap
4. Ping guest from host  (65520-28=65492, 65520 is max mtu of virtio nic)
#ping $guest_ip -I $tap -s 65492 -M do

 
Actual results:
host can ping guest successfully

Expected results:
guest abnormally quit

Additional info:
1. Command line:
# qemu-kvm -name 'vm1' -monitor tcp:0:6001,server,nowait -drive file=/root/autotest/client/tests/kvm/images/RHEL-4.8-64-virtio.qcow2,if=virtio,cache=none,boot=on -net nic,vlan=0,model=virtio,macaddr=02:70:04:52:e8:e2 -net tap,vlan=0,ifname=virtio_0_6001,script=/root/autotest/client/tests/kvm/scripts/qemu-ifup-switch,downscript=no -m 4096 -smp 2 -soundhw ac97 -vnc :0 -spice port=8000,disable-ticketing -serial unix:/tmp/serial-20100621-161808-MXgd,server,nowait -no-hpet

Comment 1 Michael S. Tsirkin 2010-09-05 17:54:27 UTC
I think this is the same issue as bz 610343: qemu
exiting on packet truncation.
https://bugzilla.redhat.com/show_bug.cgi?id=610343

Please check with kvm-83-164.el5_5.21

Comment 3 Michael S. Tsirkin 2010-09-12 13:00:20 UTC

*** This bug has been marked as a duplicate of bug 610343 ***


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