Public bug reported:
Issue discription：
Virtio split ring reconnect case failed with qemu version>4.1.0, no
throughput after reconnect from vhost-user and vhost print log
"VHOST_DATA : Failed to allocate memory for mbuf." when sending 1518
length packets.
Test Environment:
DPDK version: DPDK v20.05
OS: Linux 5.4
Compiler: gcc (Ubuntu 7.3.0-16ubuntu3) 8.4.0
Hardware platform: Purley.
The reproduce step is :
Test Case : pvp test with virtio 1.0 mergeable path
====================================================
1. Bind one port to vfio-pci, then launch testpmd by below command::
rm -rf vhost-net*
./testpmd -l 1-3 -n 4 --socket-mem 1024,1024 \
--vdev 'eth_vhost0,iface=vhost-net,queues=2,client=1' -- -i --nb-cores=2
--rxq=2 --txq=2 --txd=1024 --rxd=1024
testpmd>set fwd mac
testpmd>start
2. launch VM with different qemu version separately, note: we need add
"disable-modern=false" to enable virtio 1.0::
/home/qemu-install/qemu-4.2.0/bin/qemu-system-x86_64 -name vm0 -enable-kvm
-pidfile /tmp/.vm0.pid -daemonize -monitor
unix:/tmp/vm0_monitor.sock,server,nowait -device e1000,netdev=nttsip1 -netdev
user,id=nttsip1,hostfwd=tcp:10.67.116.150:6001-:22 -chardev
socket,id=char0,path=/root/dpdk/vhost-net,server -netdev
type=vhost-user,id=netdev0,chardev=char0,vhostforce,queues=2 -device
virtio-net-pci,netdev=netdev0,mac=52:54:00:00:00:01,disable-modern=false,mrg_rxbuf=on,rx_queue_size=1024,disable-modern=false,tx_queue_size=1024,mq=on,vectors=15
-cpu host -smp 14 -m 4096 -object
memory-backend-file,id=mem,size=4096M,mem-path=/mnt/huge,share=on -numa
node,memdev=mem -mem-prealloc -chardev
socket,path=/tmp/vm0_qga0.sock,server,nowait,id=vm0_qga0 -device virtio-serial
-device virtserialport,chardev=vm0_qga0,name=org.qemu.guest_agent.0 -vnc :4
-drive file=/home/osimg/ubuntu1910.img
3. On VM, bind virtio net to igb_uio and run testpmd without tx-
offloads::
./testpmd -c 0x7 -n 4 – -i --enable-hw-vlan-strip\
--nb-cores=2 --rxq=2 --txq=2 --txd=1024 --rxd=1024
testpmd>start
4. Send 64B and 1518B packets by packet generator separately, show
throughput with below command::
testpmd>show port stats all
5. Quit vhost-user, then re-launch, check if the reconnect can work and
ensure the traffic can continue.
6. Kill VM, then re-launch VM, check if the reconnect can work and
ensure the traffic can continue.
Analysis: this is a regression bug introduced by QEMU(bad
commit:6ab79a20af). The change adds a flag to prevent repeated calls to
vhost_net_stop(). However, it prevents any calls to vhost_net_cleanup()
from net_vhost_user_event(). This caused failure to hot-remove a vhost
user from guest because of mem leak.
** Affects: qemu (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1880665
Title:
Virtio split ring reconnect case failed with qemu version>4.1.0
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