Not able to add pcie card to guest: Operation not permitted

[Mauricio Tavares]

Let's say I have libvirt

[root at vmhost2 ~]# virsh version
Compiled against library: libvirt 4.5.0
Using library: libvirt 4.5.0
Using API: QEMU 4.5.0
Running hypervisor: QEMU 2.12.0
[root at vmhost2 ~]#

running on centos 8 and then I have this card

[root at vmhost2 ~]# virsh nodedev-dumpxml pci_0000_01_00_0
<device>
  <name>pci_0000_01_00_0</name>
  <path>/sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0</path>
  <parent>pci_0000_00_01_0</parent>
  <driver>
    <name>mlx4_core</name>
  </driver>
  <capability type='pci'>
    <domain>0</domain>
    <bus>1</bus>
    <slot>0</slot>
    <function>0</function>
    <product id='0x1003'>MT27500 Family [ConnectX-3]</product>
    <vendor id='0x15b3'>Mellanox Technologies</vendor>
    <iommuGroup number='1'>
      <address domain='0x0000' bus='0x00' slot='0x01' function='0x0'/>
      <address domain='0x0000' bus='0x01' slot='0x00' function='0x0'/>
    </iommuGroup>
    <pci-express>
      <link validity='cap' port='8' speed='8' width='8'/>
      <link validity='sta' speed='5' width='8'/>
    </pci-express>
  </capability>
</device>

which I added to the guest (arch='x86_64' machine='pc-q35-rhel7.6.0') as

    <hostdev mode='subsystem' type='pci' managed='yes'>
      <source>
        <address domain='0x0000' bus='0x01' slot='0x00' function='0x0'/>
      </source>
      <address type='pci' domain='0x0000' bus='0x08' slot='0x00'
function='0x0'/>
    </hostdev>

When I try to start the guest I get the following error message:

[root at vmhost2 ~]# virsh start testfedora
error: Failed to start domain testfedora
error: internal error: qemu unexpectedly closed the monitor:
2020-04-24T20:01:35.341020Z qemu-kvm: -device
vfio-pci,host=01:00.0,id=hostdev0,bus=pci.8,addr=0x0: vfio error:
0000:01:00.0: failed to setup INTx fd: Operation not permitted

[root at vmhost2 ~]#

Why is it telling me that is not permitted?