Comment 2 for bug 1780225

Hi,
Any update on this one?

As described here:
https://bugs.launchpad.net/nova/+bug/1797269
the problem seems to be caused by nova assigning the same mdev device UUID to multiple templates.

Here is an instance that launches correctly:

```
  <name>instance-00000241</name>
  <uuid>8b926f14-debc-4a15-a254-b068cf0366d6</uuid>
...
    <hostdev mode='subsystem' type='mdev' managed='no' model='vfio-pci'>
      <source>
        <address uuid='7f41921f-0683-4934-91e6-2102b4f63d42'/>
      </source>
      <alias name='hostdev0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
```
Here is one that breaks:

```
  <name>instance-00000240</name>
  <uuid>94b1af59-bece-4c90-9a77-5527561b978e</uuid>
...
    <hostdev mode='subsystem' type='mdev' managed='no' model='vfio-pci'>
      <source>
        <address uuid='7f41921f-0683-4934-91e6-2102b4f63d42'/>
      </source>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
```
Error message from nova-compute:

```
2019-01-23 12:18:09.690 7 ERROR nova.compute.manager [instance: 94b1af59-bece-4c90-9a77-5527561b978e] libvirtError: Requested operation is not valid: mediated device /sys/bus/mdev/devices/7f41921f-0683-4934-91e6-2102b4f63d42 is in use by driver QEMU, domain instance-00000241
```