** Changed in: qemu
Status: Incomplete => New
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https://bugs.launchpad.net/bugs/1888818
Title:
Multi-queue vhost-user fails to reconnect with qemu version >=4.2
Status in QEMU:
New
Bug description:
Test Environment:
DPDK version: DPDK v20.08
Other software versions: qemu4.2.0, qemu5.0.0.
OS: Linux 4.15.0-20-generic
Compiler: gcc (Ubuntu 7.3.0-16ubuntu3) 8.4.0
Hardware platform: Purley.
Test Setup
Steps to reproduce
List the steps to reproduce the issue.
Test flow
=========
1. Launch vhost-user testpmd as port0 with 2 queues:
./x86_64-native-linuxapp-gcc/app/testpmd -l 2-4 -n 4 \
--file-prefix=vhost --vdev 'net_vhost0,iface=vhost-net,queues=2,client=1'
-- -i --txd=1024 --rxd=1024 --txq=2 --rxq=2
testpmd>start
3. Launch qemu with virtio-net:
taskset -c 13 \
qemu-system-x86_64 -name us-vhost-vm1 \
-cpu host -enable-kvm -m 2048 -object
memory-backend-file,id=mem,size=2048M,mem-path=/mnt/huge,share=on \
-numa node,memdev=mem \
-mem-prealloc -monitor unix:/tmp/vm2_monitor.sock,server,nowait
-netdev user,id=yinan,hostfwd=tcp:127.0.0.1:6005-:22 -device e1000,netdev=yinan
\
-smp cores=1,sockets=1 -drive file=/home/osimg/ubuntu16.img \
-chardev socket,id=char0,path=./vhost-net,server \
-netdev type=vhost-user,id=mynet1,chardev=char0,vhostforce,queues=2 \
-device
virtio-net-pci,mac=52:54:00:00:00:01,netdev=mynet1,mrg_rxbuf=on,csum=on,gso=on,host_tso4=on,guest_tso4=on,mq=on,vectors=15
\
-vnc :10 -daemonize
6. Quit testpmd and restart vhost-user :
testpmd>quit
./x86_64-native-linuxapp-gcc/app/testpmd -l 2-4 -n 4 \
--file-prefix=vhost --vdev 'net_vhost0,iface=vhost-net,queues=2,client=1'
-- -i --txd=1024 --rxd=1024 --txq=2 --rxq=2
Expected Result:
After the vhost-user is killed then re-launched, the virtio-net can connect
back to vhost-user again.
Actual Result:
Vhost-user relaunch failed with continous log printed"VHOST_CONFIG:
Processing VHOST_USER_SET_FEATURES failed.
Analysis:
This is a regression bug, bad commit: c6beefd674f
When vhost-user quits, QEMU doesnot save acked features for each virtio-net
after vhost-user quits. When vhost-user reconnects to QEMU, QEMU sends two
different features(one is the true acked feature while the another is
0x40000000) to vhost-user successively which causing vhost-user exits
abnormally.
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