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  1. RHEL
  2. RHEL-333

[RHEL9]packed=on: guest fails to recover receiving packets after vhost-user reconnect

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    • sst_virtualization_networking
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      Moved to 9.5 due to lack of bandwith

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      Moved to 9.5 due to lack of bandwith
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    • Known Issue
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      .Restarting the OVS service on a host might block network connectivity on its running VMs

      When the Open vSwitch (OVS) service restarts or crashes on a host, virtual machines (VMs) that are running on this host cannot recover the state of the networking device. As a consequence, VMs might be completely unable to receive packets.

      This problem only affects systems that use the packed virtqueue format in their `virtio` networking stack.

      To work around this problem, use the `packed=off` parameter in the `virtio` networking device definition to disable packed virtqueue. With packed virtqueue disabled, the state of the networking device can, in some situations, be recovered from RAM.
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      .Restarting the OVS service on a host might block network connectivity on its running VMs When the Open vSwitch (OVS) service restarts or crashes on a host, virtual machines (VMs) that are running on this host cannot recover the state of the networking device. As a consequence, VMs might be completely unable to receive packets. This problem only affects systems that use the packed virtqueue format in their `virtio` networking stack. To work around this problem, use the `packed=off` parameter in the `virtio` networking device definition to disable packed virtqueue. With packed virtqueue disabled, the state of the networking device can, in some situations, be recovered from RAM.
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      +++ This bug was initially created as a clone of Bug #1792683 +++

      Description of problem:
      Boot guest with vhost-user packed=on. Then re-connect vhost-user by re-starting dpdk's testpmd, testpmd in guest fails to recover receiving packets.

      Version-Release number of selected component (if applicable):
      5.12.0-0.rc5.180.el9.x86_64
      qemu-kvm-5.2.0-11.el9.x86_64

      How reproducible:
      100%

      Steps to Reproduce:
      1. Boot dpdk's testpmd as vhost-user client

      1. cat pvp.sh
        /usr/bin/dpdk-testpmd \
        -l 2,4,6,8,10 \
        --socket-mem 1024,1024 \
        -n 4 \
        --vdev net_vhost0,iface=/tmp/vhost-user1,queues=1,client=1,iommu-support=1 \
        --vdev net_vhost1,iface=/tmp/vhost-user2,queues=1,client=1,iommu-support=1 \
        --block 0000:3b:00.0 --block 0000:3b:00.1 \
        -d /usr/lib64/librte_net_vhost.so \
        • \
          --portmask=f \
          -i \
          --rxd=512 --txd=512 \
          --rxq=1 --txq=1 \
          --nb-cores=4 \
          --forward-mode=io
      1. sh pvp.sh

      testpmd> set portlist 0,2,1,3
      testpmd>
      Port 0: link state change event

      Port 1: link state change event

      testpmd>
      testpmd> start

      2. Boot guest with vhost-user packed=on. Full XML is attached.

      <domain type='kvm' id='1' xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'>
      <name>rhel9.0</name>
      ...
      <devices>
      ...
      <interface type='bridge'>
      <mac address='88:66:da:5f:dd:01'/>
      <source bridge='switch'/>
      <target dev='vnet0'/>
      <model type='virtio'/>
      <alias name='net0'/>
      <address type='pci' domain='0x0000' bus='0x01' slot='0x00' function='0x0'/>
      </interface>
      <interface type='vhostuser'>
      <mac address='88:66:da:5f:dd:12'/>
      <source type='unix' path='/tmp/vhost-user1' mode='server'/>
      <model type='virtio'/>
      <driver name='vhost' rx_queue_size='1024' iommu='on' ats='on'/>
      <alias name='net1'/>
      <address type='pci' domain='0x0000' bus='0x06' slot='0x00' function='0x0'/>
      </interface>
      <interface type='vhostuser'>
      <mac address='88:66:da:5f:dd:13'/>
      <source type='unix' path='/tmp/vhost-user2' mode='server'/>
      <model type='virtio'/>
      <driver name='vhost' rx_queue_size='1024' iommu='on' ats='on'/>
      <alias name='net2'/>
      <address type='pci' domain='0x0000' bus='0x07' slot='0x00' function='0x0'/>
      </interface>
      ...
      </devices>
      ...
      <qemu:commandline>
      <qemu:arg value='-set'/>
      <qemu:arg value='device.net1.packed=on'/>
      <qemu:arg value='-set'/>
      <qemu:arg value='device.net2.packed=on'/>
      </qemu:commandline>
      </domain>

      3. Start testpmd in guest and start Moongen in another host, guest can receive packets.

      testpmd> show port stats all

      NIC statistics for port 0
      RX-packets: 2742484 RX-missed: 0 RX-bytes: 164549040
      RX-errors: 0
      RX-nombuf: 0
      TX-packets: 2738731 TX-errors: 0 TX-bytes: 164323860

      Throughput (since last show)
      Rx-pps: 70846 Rx-bps: 34006104
      Tx-pps: 70772 Tx-bps: 33971032

      NIC statistics for port 1
      RX-packets: 2740010 RX-missed: 0 RX-bytes: 164400600
      RX-errors: 0
      RX-nombuf: 0
      TX-packets: 2741234 TX-errors: 0 TX-bytes: 164474040

      Throughput (since last show)
      Rx-pps: 70771 Rx-bps: 33970192
      Tx-pps: 70853 Tx-bps: 34009640

      4. Re-connect vhost-user by re-start dpdk's testpmd in host

      1. pkill testpmd
      1. sh pvp.sh

      5. Check testpmd in guest, the packets receiving can not recover.

      testpmd> show port stats all

      NIC statistics for port 0
      RX-packets: 3034162 RX-missed: 0 RX-bytes: 182049720
      RX-errors: 0
      RX-nombuf: 0
      TX-packets: 3030089 TX-errors: 0 TX-bytes: 181805340

      Throughput (since last show)
      Rx-pps: 0 Rx-bps: 0
      Tx-pps: 0 Tx-bps: 0

      NIC statistics for port 1
      RX-packets: 3031364 RX-missed: 0 RX-bytes: 181881840
      RX-errors: 0
      RX-nombuf: 0
      TX-packets: 3032908 TX-errors: 0 TX-bytes: 181974480

      Throughput (since last show)
      Rx-pps: 0 Rx-bps: 0
      Tx-pps: 0 Tx-bps: 0

      Actual results:
      dpdk packets receiving can not recover after vhost-user reconnect.

      Expected results:
      dpdk packets receiving should recover well after vhost-user reconnect.

      Additional info:
      1. Without packed=on, dpdk packets receiving can be recovered very well.

            eperezma Eugenio PĂ©rez
            rhn-support-pezhang Pei Zhang
            YangHang Liu YangHang Liu
            Daniel Vozenilek Daniel Vozenilek
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              Created:
              Updated: