[dpdk-users] Incorrect Link State with DPDK 18.11.1 and vhost PMD

[David Christensen <drc@linux.vnet.ibm.com>]

I'm attempting to send traffic between host and guest using testpmd. 
Using the vhost PMD on the host side and the virtio PMD with vhost 
backend on the guest side.

I can successfully send traffic from the host to the guest (i.e. host 
has --forward-mode=txonly and guest has --forward-mode=rxonly)but I'm 
unable to send traffic in the opposite direction.

After further investigation I discovered that the host ports show link 
UP while the guest ports show link DOWN.  So the behavior makes sense, 
only the ports where link is UP are able to send traffic, but I don't 
understand why that might be the case.  I've also discovered that the 
testpmd commands for changing link state don't work (i.e. the command 
"set link-up port 0" fails in the guest and the command "set link-down 
port 0" fails in the host).

Has anyone encountered this situation or have experience in running this 
particular configuration?  My testpmd command line parameters for both 
are shown below, along with the qemu parameters used by the guest.

Dave

Host:
$ sudo 
/home/dave/src/p9-dpdk-perf/dpdk/ppc_64-power8-linuxapp-gcc/app/testpmd 
--vdev 'net_vhost1,queues=4,iface=/tmp/vhost-sock1' --vdev 
'net_vhost2,queues=4,iface=/tmp/vhost-sock2' -b 0000:01:00.0 -b 
0000:01:00.1 -l 8,16-23 -n 4 -- --portmask=0x3 --rxq=4 --rxd=1024 
--txq=4 --txd=4096 --nb-cores=8 -i --numa --forward-mode=rxonly

Guest:
/home/dave/src/p9-dpdk-perf/dpdk/ppc_64-power8-linuxapp-gcc/app/testpmd 
-w 00:08.0 -w 00:09.0 -l 4,8-15 -n 4 -- --rxq=4 --rxd=1024 --txq=4 
--txd=4096 --nb-cores=8 -i --forward-mode=txonly

Qemu:
LC_ALL=C PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin 
QEMU_AUDIO_DRV=none /usr/libexec/qemu-kvm -name 
guest=rhel7.6-alt,debug-threads=on -S -object 
secret,id=masterKey0,format=raw,file=/var/lib/libvirt/qemu/domain-22-rhel7.6-alt/master-key.aes 
-machine pseries-rhel7.6.0,accel=kvm,usb=off,dump-guest-core=off -cpu 
host -m 32768 -realtime mlock=off -smp 24,sockets=1,cores=24,threads=1 
-object 
memory-backend-file,id=ram-node0,prealloc=yes,mem-path=/dev/hugepages/libvirt/qemu/22-rhel7.6-alt,share=yes,size=34359738368 
-numa node,nodeid=0,cpus=0-23,memdev=ram-node0 -uuid 
081f2381-716d-40b9-8b48-2c05626c9f54 -no-user-config -nodefaults 
-chardev socket,id=charmonitor,fd=24,server,nowait -mon 
chardev=charmonitor,id=monitor,mode=control -rtc base=utc -no-shutdown 
-boot menu=on,strict=on -device qemu-xhci,id=usb,bus=pci.0,addr=0x3 
-device virtio-scsi-pci,id=scsi0,bus=pci.0,addr=0x2 -device 
virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x4 -drive 
file=/home/davec/images/rhel7.6.qcow2,format=qcow2,if=none,id=drive-virtio-disk0,cache=writeback 
-device 
virtio-blk-pci,scsi=off,bus=pci.0,addr=0x5,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=2,write-cache=on 
-drive if=none,id=drive-scsi0-0-0-0,readonly=on -device 
scsi-cd,bus=scsi0.0,channel=0,scsi-id=0,lun=0,drive=drive-scsi0-0-0-0,id=scsi0-0-0-0,bootindex=1 
-netdev tap,fd=26,id=hostnet0,vhost=on,vhostfd=27 -device 
virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:8f:e8:8b,bus=pci.0,addr=0x1 
-chardev socket,id=charnet1,path=/tmp/vhost-sock1 -netdev 
vhost-user,chardev=charnet1,queues=4,id=hostnet1 -device 
virtio-net-pci,mq=on,vectors=10,rx_queue_size=256,netdev=hostnet1,id=net1,mac=52:54:00:2a:9f:eb,bus=pci.0,addr=0x8 
-chardev socket,id=charnet2,path=/tmp/vhost-sock2 -netdev 
vhost-user,chardev=charnet2,queues=4,id=hostnet2 -device 
virtio-net-pci,mq=on,vectors=10,rx_queue_size=256,netdev=hostnet2,id=net2,mac=52:54:00:4c:83:a2,bus=pci.0,addr=0x9 
-chardev pty,id=charserial0 -device 
spapr-vty,chardev=charserial0,id=serial0,reg=0x30000000 -chardev 
socket,id=charchannel0,fd=28,server,nowait -device 
virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=org.qemu.guest_agent.0 
-device usb-kbd,id=input0,bus=usb.0,port=1 -device 
usb-mouse,id=input1,bus=usb.0,port=2 -vnc 127.0.0.1:0 -device 
VGA,id=video0,vgamem_mb=16,bus=pci.0,addr=0x7 -device 
virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x6 -sandbox 
on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny 
-msg timestamp=on