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Bug 741865

Summary: First ping will lost packages if execute "ping -I eth0(pass-through nic) under pass-through nic and emulation nic
Product: Red Hat Enterprise Linux 6 Reporter: daiwei <wdai>
Component: qemu-kvmAssignee: Alex Williamson <alex.williamson>
Status: CLOSED NOTABUG QA Contact: Virtualization Bugs <virt-bugs>
Severity: low Docs Contact:
Priority: medium    
Version: 6.2CC: acathrow, juzhang, michen, mkenneth, shuang, tburke, virt-maint
Target Milestone: rc   
Target Release: 6.2   
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2011-12-09 10:58:15 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Attachments:
Description Flags
ping screenshot none

Description daiwei 2011-09-28 08:54:53 UTC 
Description of problem:

ping lost packages when assign a pf to guest

Version-Release number of selected component (if applicable):
# uname -r
2.6.32-202.el6.x86_64

#rpm -qa|grep qemu
qemu-kvm-0.12.1.2-2.192.el6.x86_64

How reproducible:
100%

Steps to Reproduce:
1.unbind a nic form host,such as:
  # lspci |grep Ether
00:19.0 Ethernet controller: Intel Corporation 82579LM Gigabit Network Connection (rev 05)
03:00.0 Ethernet controller: Intel Corporation 82576 Gigabit Network Connection (rev 01)
03:00.1 Ethernet controller: Intel Corporation 82576 Gigabit Network Connection (rev 01)
04:00.0 Ethernet controller: Intel Corporation 82576 Gigabit Network Connection (rev 01)
04:00.1 Ethernet controller: Intel Corporation 82576 Gigabit Network Connection (rev 01)
# lspci -n|grep 04:00.1
04:00.1 0200: 8086:1526 (rev 01)
# echo "8086 1526" > /sys/bus/pci/drivers/pci-stub/new_id
# echo 0000:04:00.1 > /sys/bus/pci/devices/0000\:04\:00.1/driver/unbind
# echo 0000:04:00.1 > /sys/bus/pci/drivers/pci-stub/bind

2.boot a guset with two NIC cards,one of them is assigned nic,such as:
/usr/libexec/qemu-kvm -M rhel6.2.0 -enable-kvm -name RHEL-Server-6.2-64 -smp 2 -m 2G -uuid `uuidgen` -boot menu=on -drive file=/home/qcow2/RHEL-Server-6.2-64.qcow2,if=none,id=drive-virtio-disk0,format=qcow2,cache=none,aio=native,media=disk,werror=stop,rerror=stop -device virtio-blk-pci,drive=drive-virtio-disk0,id=virtio-blk-pci0,bootindex=1 -netdev tap,id=hostnet0,vhost=on,script=/etc/qemu-ifup -device virtio-net-pci,netdev=hostnet0,id=net0,mac=44:37:E6:5E:A3:F2,bus=pci.0,addr=0x4,id=net0 -drive if=none,media=cdrom,readonly=on,format=raw,id=drive-ide1-0-0 -device ide-drive,drive=drive-ide1-0-0,id=ide1-0-0 -vnc :1 -balloon none -monitor stdio -usb -usbdevice tablet -device pci-assign,host=04:00.1,id=h2guest_nic_1

3.if the assigned nic in guest is eth0 ,execute "ifup eth0;ping -I eth0 www.google.com"
  
Actual results:
 packages lost.

 with an attachment screenshot.

Expected results:
no package lost.

Additional info:
with "-device e1000" or "-device rtl8139" in qemu-kvm command line also have this issue.

with "-net none" in qemu-kvm command line ,pf work well in guest.
Comment 1 daiwei 2011-09-28 08:56:45 UTC 
Created attachment 525305 [details]
ping screenshot
Comment 3 juzhang 2011-09-28 09:13:51 UTC 
> Additional info:
> with "-device e1000" or "-device rtl8139" in qemu-kvm command line also have
> this issue.
> 
> with "-net none" in qemu-kvm command line ,pf work well in guest.
we just hit package loss when we first ping.second ping,... works well.
Comment 4 Dor Laor 2011-12-08 09:01:49 UTC 
Can you issue a single packet ping (ping -c 1) and provide the netdumps and arp tables?
Comment 5 Alex Williamson 2011-12-08 22:53:20 UTC 
Is the guest configured to use dhcp or static ip address?

Is there a time factor?  For instance do you get the same result from:

  # ifup eth0; ping -I eth0 www.google.com

as from

  # ifup eth0; sleep 30; ping -I eth0 www.google.com

If you ifdown and re-do the test, do you again experience some packets lost or is it once per boot?

I could imagine emulated devices could drop packets if the bridge forwarding delay is set wrong.  In those cases, what bridge is being used and how is it configured?

I agree with Dor that it would be useful to see tcpdumps.
Comment 6 daiwei 2011-12-09 10:58:15 UTC 
At Alex's suggestion,I re-do the test,add "sleep 30" and then no package lost.