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Hot-unplugging a vhost network device leaks references to VFIOPCIDevice's. This causes that, when trying to hot-unplug one of those VFIO devices, QEMU can't finalize it properly because the references never reach 0.

So far, we've identified the following scenarios (100% reproducible):

---
 1. Start a VM with both a VIRTIO network device and a VFIO hostdev.
 2. Hot-unplug the VIRTIO device.
 3. Hot-unplug the VFIO -> QEMU can't finalize the device: ref=2
---
 1. Start a VM with just a VFIO hostdev.
 2. Hot-plug the VIRTIO device.
 3. Hot-unplug the VFIO -> QEMU can't finalize the device: ref=2
---
 1. Start a VM with just a VFIO hostdev.
 2. Hot-plug the VIRTIO device.
 3. Hot-unplug the VIRTIO device.
 4. Hot-unplug the VFIO -> QEMU can't finalize the device: ref=2
---

There's a patch for this posted in QEMU's mailing list:

 - http://lists.nongnu.org/archive/html/qemu-devel/2017-09/msg01787.html

Fix included in qemu-kvm-rhev-2.10.0-2.el7

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHSA-2018:1104