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Description of problem:
Boot guest with vhost-user and vIOMMU, when the backend does not support IOMMU,
Qemu terminal will repeat popup error info:
"qemu-kvm: failed to init vhost_net for queue 0
vhost lacks feature mask 8589934592 for backend "
Then rebooting VM will cause qemu segmentation fault.
Version-Release number of selected component (if applicable):
3.10.0-685.el7.x86_64
qemu-kvm-rhev-2.9.0-12.el7.x86_64
libvirt-3.2.0-14.el7.x86_64
openvswitch-2.7.0-8.git20170530.el7fdb.x86_64
dpdk-17.05-2.el7fdb.x86_64
How reproducible:
100%
Steps to Reproduce:
1. Start ovs
2. Boot VM with vhost-user and vIOMMU, qemu terminal will repeat promote error info.
/usr/libexec/qemu-kvm \
-name guest=rhel7.4_nonrt \
-machine q35,kernel-irqchip=split \
-device intel-iommu,device-iotlb=on,intremap \
-cpu host \
-m 8192 \
-smp 6,sockets=1,cores=6,threads=1 \
-device pcie-root-port,id=root.1,slot=1 \
-device pcie-root-port,id=root.2,slot=2 \
-device pcie-root-port,id=root.3,slot=3 \
-object memory-backend-file,id=ram-node0,prealloc=yes,mem-path=/dev/hugepages,share=yes,size=8589934592,host-nodes=1,policy=bind \
-numa node,nodeid=0,cpus=0-5,memdev=ram-node0 \
-drive file=/home/images_nfv-virt-rt-kvm/rhel7.4_nonrt.qcow2,format=qcow2,if=none,id=drive-virtio-disk0,cache=none,aio=threads \
-device virtio-blk-pci,scsi=off,bus=root.1,drive=drive-virtio-disk0,id=virtio-disk0 \
-chardev socket,id=charnet1,path=/tmp/vhostuser0.sock,server \
-netdev vhost-user,chardev=charnet1,id=hostnet1 \
-device virtio-net-pci,mq=on,netdev=hostnet1,id=net1,mac=88:66:da:5f:dd:12,bus=root.2,iommu_platform=on,ats=on \
-chardev socket,id=charnet2,path=/tmp/vhostuser1.sock,server \
-netdev vhost-user,chardev=charnet2,id=hostnet2 \
-device virtio-net-pci,mq=on,netdev=hostnet2,id=net2,mac=88:66:da:5f:dd:13,bus=root.3,iommu_platform=on,ats=on \
-monitor stdio \
-vnc :2 \
-netdev tap,id=hostnet0,vhost=on \
-device virtio-net-pci,netdev=hostnet0,id=net0,mac=88:66:da:5f:dd:11 \
qemu-kvm: failed to init vhost_net for queue 0
vhost lacks feature mask 8589934592 for backend
...
3. Reboot VM, qemu core dump
...
vhost lacks feature mask 8589934592 for backend
qemu-kvm: failed to init vhost_net for queue 0
Segmentation fault
Actual results:
Boot VM cause qemu repeat popup error info, and reboot VM will cause qemu core dump.
Expected results:
When the backend does not support IOMMU, probably qemu should give some friendly warning message. And qemu should not core dump when reboot the VM.
Additional info:
1. This issue was found when verifying bug[1].
[1]Bug 1451862 - IOMMU support in QEMU for Vhost-user backend
2. As dpdk does not support IOMMU, so set 7.5 flag.
Hi Pei,
Could you please retry with dpdk v17.11-rc4 tag?
Testpmd's cmdline requires a new Vhost PMD parameter (iommu-support):
--vdev 'net_vhost0,iface=/tmp/vhost-user1,iommu-support=1'
Thanks,
Maxime