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[Oleg Bondarev <obondarev@xxxxxxxxxxxx>]

Public bug reported:

When a VM instantiated with a PF-PT (direct-physical) port, the Neutron
SR-IOV agent removes the respective embedded switch device instance from
the switch manager. After the VM releases the PF, the associated device
(sys/class/net/<device>) appears immediately, but the initialization of
its VFs and the creation of the appropriate sysfs entries
(/sys/class/net/<device>/device/virtfn<#vf>) may even take more than a
second, depending on the platform and the NIC's kernel driver
capabilities. The Neutron SR-IOV agent eagerly tries to discover and
register NIC devices, that are not blacklisted and not yet known, by
creating the respective embedded switch instances and enumerating the
avalable VFs underneat them. However, when it is done in an early phase,
where the sysfs entries for the VFs are not yet present, because the PF
has just been released, then a port-less embedded switch will be created
to represent that device. As a consequence, port updates that target VFs
which are supposed to belong to a incorrectly registered embedded
device, won't be treated properly by the agent, causing a VM
instantiation timeout.

** Affects: neutron
     Importance: Undecided
     Assignee: Oleg Bondarev (obondarev)
         Status: In Progress


** Tags: sriov-pci-pt

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https://bugs.launchpad.net/bugs/1831622

Title:
  SRIOV: agent may not register VFs

Status in neutron:
  In Progress

Bug description:
  When a VM instantiated with a PF-PT (direct-physical) port, the
  Neutron SR-IOV agent removes the respective embedded switch device
  instance from the switch manager. After the VM releases the PF, the
  associated device (sys/class/net/<device>) appears immediately, but
  the initialization of its VFs and the creation of the appropriate
  sysfs entries (/sys/class/net/<device>/device/virtfn<#vf>) may even
  take more than a second, depending on the platform and the NIC's
  kernel driver capabilities. The Neutron SR-IOV agent eagerly tries to
  discover and register NIC devices, that are not blacklisted and not
  yet known, by creating the respective embedded switch instances and
  enumerating the avalable VFs underneat them. However, when it is done
  in an early phase, where the sysfs entries for the VFs are not yet
  present, because the PF has just been released, then a port-less
  embedded switch will be created to represent that device. As a
  consequence, port updates that target VFs which are supposed to belong
  to a incorrectly registered embedded device, won't be treated properly
  by the agent, causing a VM instantiation timeout.

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