Proposed libvirt package on Hirsute system with original unmodified kernel and d
river:
$ uname -a
Linux node-laveran 5.11.0-31-generic #33-Ubuntu SMP Wed Aug 11 13:19:04 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

$ sudo lshw|grep mlx5_core
                configuration: autonegotiation=on broadcast=yes driver=mlx5_core driverversion=5.11.0-31-generic firmware=16.31.1014 (MT_0000000183) latency=0 link=no multicast=yes
...

$ lspci -nnvv | grep Mellanox
03:00.0 Ethernet controller [0200]: Mellanox Technologies MT27800 Family [ConnectX-5] [15b3:1017]
        Subsystem: Mellanox Technologies MT27800 Family [ConnectX-5] [15b3:0061]
03:00.1 Ethernet controller [0200]: Mellanox Technologies MT27800 Family [ConnectX-5] [15b3:1017]
        Subsystem: Mellanox Technologies MT27800 Family [ConnectX-5] [15b3:0061]
03:00.2 Ethernet controller [0200]: Mellanox Technologies MT27800 Family [ConnectX-5 Virtual Function] [15b3:1018]
        Subsystem: Mellanox Technologies MT27800 Family [ConnectX-5 Virtual Function] [15b3:0061]
...

$ dpkg -l | grep libvirt
ii  libvirt-clients                       7.0.0-2ubuntu2.1                                                     amd64        Programs for the libvirt library
ii  libvirt-daemon                        7.0.0-2ubuntu2.1                                                     amd64        Virtualization daemon
ii  libvirt-daemon-config-network         7.0.0-2ubuntu2.1                                                     all          Libvirt daemon configuration files (default network)
ii  libvirt-daemon-config-nwfilter        7.0.0-2ubuntu2.1                                                     all          Libvirt daemon configuration files (default network filters)
ii  libvirt-daemon-driver-qemu            7.0.0-2ubuntu2.1                                                     amd64        Virtualization daemon QEMU connection driver
ii  libvirt-daemon-system                 7.0.0-2ubuntu2.1                                                     amd64        Libvirt daemon configuration files
ii  libvirt-daemon-system-systemd         7.0.0-2ubuntu2.1                                                     all          Libvirt daemon configuration files (systemd)
ii  libvirt0:amd64                        7.0.0-2ubuntu2.1                                                     amd64        library for interfacing with different virtualization systems

$ sudo grep -A6 hostdev /etc/libvirt/qemu/instance-00000002.xml
    <interface type='hostdev' managed='yes'>
      <mac address='fa:16:3e:3e:af:3d'/>
      <source>
        <address type='pci' domain='0x0000' bus='0x03' slot='0x00' function='0x2'/>
      </source>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
    </interface>

$ openstack server list --long
| 9de43d8a-b63b-4747-9f6a-5ca20a501450 | fnord-node-laveran-1 | ACTIVE | None       | Running     | network=10.42.3.233                 | auto-sync/ubuntu-focal-20.04-amd64-server-20210825-disk1.img | ee06a053-c350-474c-a03f-cf0afcb35591 | m1.large    | 29873860-7b2e-49ad-a290-9a2d0600369d | nova              | node-laveran.maas |            |

$ ssh fnord-node-laveran-1 lspci
...
00:03.0 Ethernet controller: Mellanox Technologies MT27800 Family [ConnectX-5 Virtual Function]
...

<install OFED drivers, reboot and restart instances>

$ uname -a
Linux node-laveran 5.11.0-31-generic #33-Ubuntu SMP Wed Aug 11 13:19:04 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

$ sudo lshw|grep mlx5_core
                configuration: autonegotiation=on broadcast=yes driver=mlx5_core driverversion=5.4-1.0.3 duplex=full firmware=16.31.1014 (MT_0000000183) latency=0 link=yes multicast=yes slave=yes speed=10Gbit/s

$ ssh fnord-node-laveran-1 lspci
...
00:03.0 Ethernet controller: Mellanox Technologies MT27800 Family [ConnectX-5 Virtual Function]
...