[libvirt-users] "scripts are not supported on interfaces of type vhostuser" error

Discussion:

Riccardo Ravaioli

2018-02-22 16:41:14 UTC

Hi,

I'm having trouble starting a VM with vhostuser interfaces.

I have a simple configuration where a VM running Debian has 1 vhostuser
interface plugged into an OVS switch where a DPDK interface is already
plugged in.
$ ovs-vsctl show:
Bridge "switch1"
Port "switch1"
Interface "switch1"
type: internal
Port "1.switch1"
Interface "1.switch1"
type: dpdk
options: {dpdk-devargs="0000:0b:00.0"}
Port "0.switch1"
Interface "0.vm"
type: dpdkvhostuserclient
options: {vhost-server-path="/opt/oa/vhost/0.vm.sock"}

The relevant excerpt from the XML of my VM is:

<?xml version="1.0" ?>
<domain type="kvm" xmlns:ns0="http://libvirt.org/schemas/domain/qemu/1.0">

<devices>
<emulator>/opt/oa/bin/qemu-system-x86_64</emulator>

<interface type="vhostuser">
<script path="/opt/oa/etc/qemu-ifup"/>
<source mode="server" path="/opt/oa/vhost/0.vm.sock" type="unix"/>
<mac address="52:54:00:41:37:08"/>
<model type="virtio"/>
<driver queues="1">
<host csum="off"/>
</driver>
</interface>

</devices>
<ns0:commandline>
<ns0:arg value="-object"/>
<ns0:arg
value="memory-backend-file,id=mem,size=2G,mem-path=/dev/hugepages,share=on"/>
<ns0:arg value="-numa"/>
<ns0:arg value="node,memdev=mem"/>
<ns0:arg value="-mem-prealloc"/>
</ns0:commandline>
</domain>

Now, if I try to start my VM, I get the following error and the VM is not
started at all:
$ virsh create vm.xml
error: Failed to create domain from vm.xml
error: unsupported configuration: scripts are not supported on interfaces
of type vhostuser

The logs from libvirtd.log say:
2018-02-22 09:18:24.982+0000: 2033: warning :
qemuProcessStartWarnShmem:4539 : Detected vhost-user interface without any
shared memory, the interface might not be operational
2018-02-22 09:18:24.982+0000: 2033: error : qemuBuildHostNetStr:3894 :
unsupported configuration: scripts are not supported on interfaces of type
vhostuser

The logs from qemu simply say:
2018-02-22 09:26:15.857+0000: shutting down, reason=failed

And finally, ovs-vswitchd.log:
2018-02-22T09:18:24.715Z|00328|dpdk|INFO|VHOST_CONFIG: vhost-user client:
socket created, fd: 51
2018-02-22T09:18:24.716Z|00329|netdev_dpdk|INFO|vHost User device '0.vm'
created in 'client' mode, using client socket '/opt/oa/vhost/0.vm.sock'
2018-02-22T09:18:24.718Z|00330|dpdk|WARN|VHOST_CONFIG: failed to connect to
/opt/oa/vhost/0.vm.sock: No such file or directory
2018-02-22T09:18:24.718Z|00331|dpdk|INFO|VHOST_CONFIG:
/opt/oa/vhost/0.vm.sock: reconnecting...
2018-02-22T09:18:24.718Z|00332|bridge|INFO|bridge switch1: added interface
0.vm on port 5

Am I missing something on the openvswitch or on the libvirt side?

It looks like openvswitch can't find /opt/oa/vhost/0.vm.sock, but isn't
either openvswitch or libvirt in charge of creating it?
Then, I'm not too sure about the error messages in libvirtd.log...

My software versions are: libvirt 3.10.0, qemu 2.10.2, openvswitch 2.8.1
and DPDK 17.11.

Thanks a lot!

Riccardo

Laine Stump

2018-02-22 19:55:21 UTC

Permalink

Post by Riccardo Ravaioli
Hi,
I'm having trouble starting a VM with vhostuser interfaces.
I have a simple configuration where a VM running Debian has 1 vhostuser
interface plugged into an OVS switch where a DPDK interface is already
plugged in.
Bridge "switch1"
    Port "switch1"
        Interface "switch1"
            type: internal
    Port "1.switch1"
        Interface "1.switch1"
            type: dpdk
            options: {dpdk-devargs="0000:0b:00.0"}
    Port "0.switch1"
        Interface "0.vm"
            type: dpdkvhostuserclient
            options: {vhost-server-path="/opt/oa/vhost/0.vm.sock"}
<?xml version="1.0" ?>
<domain type="kvm" xmlns:ns0="http://libvirt.org/schemas/domain/qemu/1.0">

<devices>
    <emulator>/opt/oa/bin/qemu-system-x86_64</emulator>
    
    <interface type="vhostuser">
      <script path="/opt/oa/etc/qemu-ifup"/>

^^^^^^^^^^^^^^^^ Why do you have this line?

Post by Riccardo Ravaioli
      <source mode="server" path="/opt/oa/vhost/0.vm.sock" type="unix"/>
      <mac address="52:54:00:41:37:08"/>
      <model type="virtio"/>
      <driver queues="1">
        <host csum="off"/>
      </driver>
    </interface>
    
</devices>
<ns0:commandline>
    <ns0:arg value="-object"/>
    <ns0:arg
value="memory-backend-file,id=mem,size=2G,mem-path=/dev/hugepages,share=on"/>
    <ns0:arg value="-numa"/>
    <ns0:arg value="node,memdev=mem"/>
    <ns0:arg value="-mem-prealloc"/>
</ns0:commandline>
</domain>
Now, if I try to start my VM, I get the following error and the VM is
$ virsh create vm.xml
error: Failed to create domain from vm.xml
error: unsupported configuration: scripts are not supported on
interfaces of type vhostuser

This error message tells you exactly what is wrong. The <script> element
is only supported for interfaces of type='ethernet' - these are
interfaces for which a tap device is created, but it's not connected to
anything; the purpose of the script is to connect the tap to device to
[something user-defined]. Other types of interface (e.g. vhost-user)
should have enough intelligence built into the code to perform all
necessary setup.

Do you actually have something in this qemu-ifup file?

Post by Riccardo Ravaioli
qemuProcessStartWarnShmem:4539 : Detected vhost-user interface without
any shared memory, the interface might not be operational
unsupported configuration: scripts are not supported on interfaces of
type vhostuser
2018-02-22 09:26:15.857+0000: shutting down, reason=failed
2018-02-22T09:18:24.715Z|00328|dpdk|INFO|VHOST_CONFIG: vhost-user
client: socket created, fd: 51
2018-02-22T09:18:24.716Z|00329|netdev_dpdk|INFO|vHost User device '0.vm'
created in 'client' mode, using client socket '/opt/oa/vhost/0.vm.sock'
2018-02-22T09:18:24.718Z|00330|dpdk|WARN|VHOST_CONFIG: failed to connect
to /opt/oa/vhost/0.vm.sock: No such file or directory
/opt/oa/vhost/0.vm.sock: reconnecting...
2018-02-22T09:18:24.718Z|00332|bridge|INFO|bridge switch1: added
interface 0.vm on port 5
Am I missing something on the openvswitch or on the libvirt side?
It looks like openvswitch can't find /opt/oa/vhost/0.vm.sock, but isn't
either openvswitch or libvirt in charge of creating it?
Then, I'm not too sure about the error messages in libvirtd.log...
My software versions are: libvirt 3.10.0, qemu 2.10.2, openvswitch 2.8.1
and DPDK 17.11.
Thanks a lot!
Riccardo
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Riccardo Ravaioli

2018-02-23 10:21:46 UTC

Permalink

Spot on! The script qemu-ifup was indeed the cause of the problem. It's a
dummy script that only does "exit 0" and it was apparently needed in the
past with old versions of libvirt. I see examples on the net where it is
used to configure interfaces with shell commands. I don't need it.

I see that everything works fine without the <script
path="/opt/oa/etc/qemu-ifup"/> line, for vhostuser and ethernet interfaces.
Are there any side effects or can I safely remove that line?

Thanks again!

Riccardo

Post by Laine Stump
[...]

Post by Riccardo Ravaioli
<interface type="vhostuser">
<script path="/opt/oa/etc/qemu-ifup"/>

^^^^^^^^^^^^^^^^ Why do you have this line?
Spo> $ virsh create vm.xml

Post by Riccardo Ravaioli
error: Failed to create domain from vm.xml
error: unsupported configuration: scripts are not supported on
interfaces of type vhostuser

This error message tells you exactly what is wrong. The <script> element
is only supported for interfaces of type='ethernet' - these are
interfaces for which a tap device is created, but it's not connected to
anything; the purpose of the script is to connect the tap to device to
[something user-defined]. Other types of interface (e.g. vhost-user)
should have enough intelligence built into the code to perform all
necessary setup.
Do you actually have something in this qemu-ifup file?

Laine Stump

2018-02-23 21:55:33 UTC

Permalink

Post by Riccardo Ravaioli
Spot on! The script qemu-ifup was indeed the cause of the problem. It's
a dummy script that only does "exit 0" and it was apparently needed in
the past with old versions of libvirt.

Only if you previously used interfaces of type='ethernet' that required
some external action when the interface was started.

Post by Riccardo Ravaioli
I see examples on the net where
it is used to configure interfaces with shell commands. I don't need it.
I see that everything works fine without the <script
path="/opt/oa/etc/qemu-ifup"/> line, for vhostuser and ethernet
interfaces. Are there any side effects or can I safely remove that line?

Since that line is causing an error when you try to start the domain
(since it is not supported or allowed for type='vhost-user', nor has it
*ever* been supported as far as I know), definitely remove the <script>
line from your config.

Michal Privoznik

2018-02-23 09:04:38 UTC

Permalink

Post by Riccardo Ravaioli
Hi,
I'm having trouble starting a VM with vhostuser interfaces.
I have a simple configuration where a VM running Debian has 1 vhostuser
interface plugged into an OVS switch where a DPDK interface is already
plugged in.
Bridge "switch1"
Port "switch1"
Interface "switch1"
type: internal
Port "1.switch1"
Interface "1.switch1"
type: dpdk
options: {dpdk-devargs="0000:0b:00.0"}
Port "0.switch1"
Interface "0.vm"
type: dpdkvhostuserclient
options: {vhost-server-path="/opt/oa/vhost/0.vm.sock"}
<?xml version="1.0" ?>
<domain type="kvm" xmlns:ns0="http://libvirt.org/schemas/domain/qemu/1.0">

<devices>
<emulator>/opt/oa/bin/qemu-system-x86_64</emulator>

<interface type="vhostuser">
<script path="/opt/oa/etc/qemu-ifup"/>
<source mode="server" path="/opt/oa/vhost/0.vm.sock" type="unix"/>
<mac address="52:54:00:41:37:08"/>
<model type="virtio"/>
<driver queues="1">
<host csum="off"/>
</driver>
</interface>

</devices>
<ns0:commandline>
<ns0:arg value="-object"/>
<ns0:arg
value="memory-backend-file,id=mem,size=2G,mem-path=/dev/hugepages,share=on"/>
<ns0:arg value="-numa"/>
<ns0:arg value="node,memdev=mem"/>
<ns0:arg value="-mem-prealloc"/>
</ns0:commandline>

Unrelated, to avoid command line passthrough you can do:

<domain>
<memoryBacking>
<hugepages/>
</memoryBacking>
..
<cpu>
<numa>
<cell id='0' cpus='$CPUS' memory='$MEM' memAccess='shared'/>
</numa>
</cpu>
..
</domain>

Michal