[Pkg-libvirt-maintainers] Bug#1107536: Bug#1107536: PPC64LE: Device hotplug/unplug requires guest reboot

Tue Jun 10 07:59:45 BST 2025

On 2025-06-09 23:38, Andrea Bolognani wrote:
> On Mon, Jun 09, 2025 at 09:50:24AM +0530, Trupti wrote:
>> Package: libvirt-daemon
>> Severity: important
>> Tags: trixie ppc64el
>> 
>> Version Info:
>> 
>> Host/Guest OS: Debian Trixie/sid (powerpc64le)
>> Kernel: 6.12.27-powerpc64le-64k
>> QEMU: 10.0.0
>> Libvirt: 11.3.0
>> 
>> Issue:
>> 
>> Live-attaching or detaching a device with virsh on a Debian Trixie 
>> (ppc64le)
>> guest does not take effect immediately. While the host command 
>> succeeds, the
>> guest OS only recognizes the change after a full reboot. This defeats 
>> the
>> purpose of the hotplug feature.
>> 
>> Steps to reproduce:
>> 1) Start a guest with Debian-Trixie OS same as Host
>> 2) Attach an interface to guest using below virsh attach-device 
>> command
>>    'virsh attach-interface --live vm bridge --source virbr0'
>> 3) The command executes successfully and give output as "Interface 
>> attached
>> successfully"
>> 4) But the interface is not immediately attached to guest. When the 
>> guest is
>> rebooted , then the
>>    interface is seen on the guest.
>> 5) Same is happening with virsh detach-interface command. A guest 
>> reboot is
>> required to remove
>>    the interface from guest
> 
> What's the output of attach-interface if you pass the --print-xml
> flag to it? What does the full live XML look like before and after
> the operation?
> 
    I have gathered the diagnostic information you requested.

    virsh attach-interface --live vm bridge --source virbr0 --print-xml

    The command produced the following output:
    <interface type='bridge'>
       <source bridge='virbr0'/>
    </interface>

     I have attached the two files, before.xml and after.xml.

> Honestly this sounds like a guest OS issue rather than a bug in
> libvirt. Is any message produced in dmesg/journal as a consequence of
> the hotplug operation?

The guest dmesg shows the RTAS hot-plug signal, but no further messages 
appear.

Thanks Trupti
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<domain type='qemu' id='1'>
  <name>vm</name>
  <uuid>80dcb65d-7a83-4b7d-931e-0540a6fdd44c</uuid>
  <memory unit='KiB'>6291456</memory>
  <currentMemory unit='KiB'>6291456</currentMemory>
  <vcpu placement='static'>4</vcpu>
  <resource>
    <partition>/machine</partition>
  </resource>
  <os>
    <type arch='ppc64le' machine='pseries-10.0'>hvm</type>
    <boot dev='hd'/>
  </os>
  <cpu mode='custom' match='exact' check='none'>
    <model fallback='forbid'>POWER10</model>
  </cpu>
  <clock offset='utc'/>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>destroy</on_crash>
  <devices>
    <emulator>/usr/bin/qemu-system-ppc64le</emulator>
    <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2'/>
      <source file='/var/lib/libvirt/images/debian-test.qcow2' index='2'/>
      <backingStore/>
      <target dev='vda' bus='virtio'/>
      <alias name='virtio-disk0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
    </disk>
    <disk type='file' device='cdrom'>
      <driver name='qemu'/>
      <target dev='sda' bus='scsi'/>
      <readonly/>
      <alias name='scsi0-0-0-0'/>
      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
    </disk>
    <controller type='usb' index='0' model='qemu-xhci' ports='15'>
      <alias name='usb'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
    </controller>
    <controller type='scsi' index='0' model='virtio-scsi'>
      <alias name='scsi0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
    </controller>
    <controller type='pci' index='0' model='pci-root'>
      <model name='spapr-pci-host-bridge'/>
      <target index='0'/>
      <alias name='pci.0'/>
    </controller>
    <controller type='virtio-serial' index='0'>
      <alias name='virtio-serial0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
    </controller>
    <interface type='bridge'>
      <mac address='52:54:00:87:92:27'/>
      <source bridge='virbr0'/>
      <target dev='vnet0'/>
      <model type='virtio'/>
      <alias name='net0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'/>
    </interface>
    <serial type='pty'>
      <source path='/dev/pts/1'/>
      <target type='spapr-vio-serial' port='0'>
        <model name='spapr-vty'/>
      </target>
      <alias name='serial0'/>
      <address type='spapr-vio' reg='0x30000000'/>
    </serial>
    <console type='pty' tty='/dev/pts/1'>
      <source path='/dev/pts/1'/>
      <target type='serial' port='0'/>
      <alias name='serial0'/>
      <address type='spapr-vio' reg='0x30000000'/>
    </console>
    <channel type='unix'>
      <source mode='bind' path='/run/libvirt/qemu/channel/1-vm/org.qemu.guest_agent.0'/>
      <target type='virtio' name='org.qemu.guest_agent.0' state='connected'/>
      <alias name='channel0'/>
      <address type='virtio-serial' controller='0' bus='0' port='1'/>
    </channel>
    <audio id='1' type='none'/>
    <memballoon model='virtio'>
      <alias name='balloon0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
    </memballoon>
    <panic model='pseries'/>
  </devices>
  <seclabel type='dynamic' model='apparmor' relabel='yes'>
    <label>libvirt-80dcb65d-7a83-4b7d-931e-0540a6fdd44c</label>
    <imagelabel>libvirt-80dcb65d-7a83-4b7d-931e-0540a6fdd44c</imagelabel>
  </seclabel>
  <seclabel type='dynamic' model='dac' relabel='yes'>
    <label>+64055:+64055</label>
    <imagelabel>+64055:+64055</imagelabel>
  </seclabel>
</domain>

-------------- next part --------------
<domain type='qemu' id='1'>
  <name>vm</name>
  <uuid>80dcb65d-7a83-4b7d-931e-0540a6fdd44c</uuid>
  <memory unit='KiB'>6291456</memory>
  <currentMemory unit='KiB'>6291456</currentMemory>
  <vcpu placement='static'>4</vcpu>
  <resource>
    <partition>/machine</partition>
  </resource>
  <os>
    <type arch='ppc64le' machine='pseries-10.0'>hvm</type>
    <boot dev='hd'/>
  </os>
  <cpu mode='custom' match='exact' check='none'>
    <model fallback='forbid'>POWER10</model>
  </cpu>
  <clock offset='utc'/>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>destroy</on_crash>
  <devices>
    <emulator>/usr/bin/qemu-system-ppc64le</emulator>
    <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2'/>
      <source file='/var/lib/libvirt/images/debian-test.qcow2' index='2'/>
      <backingStore/>
      <target dev='vda' bus='virtio'/>
      <alias name='virtio-disk0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
    </disk>
    <disk type='file' device='cdrom'>
      <driver name='qemu'/>
      <target dev='sda' bus='scsi'/>
      <readonly/>
      <alias name='scsi0-0-0-0'/>
      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
    </disk>
    <controller type='usb' index='0' model='qemu-xhci' ports='15'>
      <alias name='usb'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
    </controller>
    <controller type='scsi' index='0' model='virtio-scsi'>
      <alias name='scsi0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
    </controller>
    <controller type='pci' index='0' model='pci-root'>
      <model name='spapr-pci-host-bridge'/>
      <target index='0'/>
      <alias name='pci.0'/>
    </controller>
    <controller type='virtio-serial' index='0'>
      <alias name='virtio-serial0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
    </controller>
    <interface type='bridge'>
      <mac address='52:54:00:87:92:27'/>
      <source bridge='virbr0'/>
      <target dev='vnet0'/>
      <model type='virtio'/>
      <alias name='net0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'/>
    </interface>
    <interface type='bridge'>
      <mac address='52:54:00:a2:19:7a'/>
      <source bridge='virbr0'/>
      <target dev='vnet3'/>
      <model type='rtl8139'/>
      <alias name='net1'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/>
    </interface>
    <serial type='pty'>
      <source path='/dev/pts/1'/>
      <target type='spapr-vio-serial' port='0'>
        <model name='spapr-vty'/>
      </target>
      <alias name='serial0'/>
      <address type='spapr-vio' reg='0x30000000'/>
    </serial>
    <console type='pty' tty='/dev/pts/1'>
      <source path='/dev/pts/1'/>
      <target type='serial' port='0'/>
      <alias name='serial0'/>
      <address type='spapr-vio' reg='0x30000000'/>
    </console>
    <channel type='unix'>
      <source mode='bind' path='/run/libvirt/qemu/channel/1-vm/org.qemu.guest_agent.0'/>
      <target type='virtio' name='org.qemu.guest_agent.0' state='connected'/>
      <alias name='channel0'/>
      <address type='virtio-serial' controller='0' bus='0' port='1'/>
    </channel>
    <audio id='1' type='none'/>
    <memballoon model='virtio'>
      <alias name='balloon0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
    </memballoon>
    <panic model='pseries'/>
  </devices>
  <seclabel type='dynamic' model='apparmor' relabel='yes'>
    <label>libvirt-80dcb65d-7a83-4b7d-931e-0540a6fdd44c</label>
    <imagelabel>libvirt-80dcb65d-7a83-4b7d-931e-0540a6fdd44c</imagelabel>
  </seclabel>
  <seclabel type='dynamic' model='dac' relabel='yes'>
    <label>+64055:+64055</label>
    <imagelabel>+64055:+64055</imagelabel>
  </seclabel>
</domain>