virtiofs Illegal Seek Error because of ivshmem device of looking-glass
Description of problem:
tl;dr: The dev "gnif" from looking-glass does not want to analyse this problem which his config from the documentation is causing. He insists someone opens a issue here at qemu's, so thats what i did now :) He also insists this problem is not caused by his config (even though the config is needed for looking-glass) and does not want to help or analyse this whole mess. Sorry if i'm a bit salty. 

Please see the following issues on his and the virtio-win github : \
https://github.com/gnif/LookingGlass/issues/1089

https://github.com/gnif/LookingGlass/issues/1083

[https://github.com/virtio-win/kvm-guest-drivers-windows/issues/911](https://github.com/virtio-win/kvm-guest-drivers-windows/issues/911%5C)

#
Steps to reproduce:
1. Create a VM
2. enable looking-glass (i used the latest Beta6 release from github) with the mentioned kernel module (i use manjaro and can use looking-glass-module-dkms from AUR)
3. add virtiofs from virt-manager
Additional information:
libvirt XML

```plaintext
<domain xmlns:qemu="http://libvirt.org/schemas/domain/qemu/1.0" type="kvm">
  <name>win10</name>
  <uuid>a026f749-3adc-4ab8-a5cf-521a4e8ec9d6</uuid>
  <metadata>
    <libosinfo:libosinfo xmlns:libosinfo="http://libosinfo.org/xmlns/libvirt/domain/1.0">
      <libosinfo:os id="http://microsoft.com/win/10"/>
    </libosinfo:libosinfo>
  </metadata>
  <memory unit="KiB">12582912</memory>
  <currentMemory unit="KiB">12582912</currentMemory>
  <memoryBacking>
    <source type="memfd"/>
    <access mode="shared"/>
  </memoryBacking>
  <vcpu placement="static">10</vcpu>
  <os>
    <type arch="x86_64" machine="pc-q35-5.1">hvm</type>
    <loader readonly="yes" type="pflash">/usr/share/edk2-ovmf/x64/OVMF_CODE.fd</loader>
    <nvram>/var/lib/libvirt/qemu/nvram/win10_VARS.fd</nvram>
  </os>
  <features>
    <acpi/>
    <apic/>
    <hyperv mode="custom">
      <relaxed state="on"/>
      <vapic state="on"/>
      <spinlocks state="on" retries="8191"/>
      <vendor_id state="on" value="ASRock"/>
    </hyperv>
    <vmport state="off"/>
  </features>
  <cpu mode="host-passthrough" check="none" migratable="on">
    <topology sockets="1" dies="1" cores="5" threads="2"/>
  </cpu>
  <clock offset="localtime">
    <timer name="hpet" present="yes"/>
    <timer name="hypervclock" present="yes"/>
  </clock>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>restart</on_crash>
  <pm>
    <suspend-to-mem enabled="no"/>
    <suspend-to-disk enabled="yes"/>
  </pm>
  <devices>
    <emulator>/usr/bin/qemu-system-x86_64</emulator>
    <disk type="file" device="cdrom">
      <driver name="qemu" type="raw"/>
      <target dev="sdc" bus="sata"/>
      <readonly/>
      <boot order="1"/>
      <address type="drive" controller="0" bus="0" target="0" unit="2"/>
    </disk>
    <disk type="file" device="disk">
      <driver name="qemu" type="qcow2" cache="none" discard="unmap"/>
      <source file="/opt/windowsos.qcow2"/>
      <target dev="sdd" bus="scsi"/>
      <boot order="2"/>
      <address type="drive" controller="0" bus="0" target="0" unit="3"/>
    </disk>
    <disk type="block" device="disk">
      <driver name="qemu" type="raw" cache="none" io="native" discard="unmap"/>
      <source dev="/dev/zvol/satassd2tb/vms/windowsdata2"/>
      <target dev="sde" bus="scsi"/>
      <address type="drive" controller="0" bus="0" target="0" unit="4"/>
    </disk>
    <controller type="usb" index="0" model="qemu-xhci" ports="15">
      <address type="pci" domain="0x0000" bus="0x02" slot="0x00" function="0x0"/>
    </controller>
    <controller type="pci" index="0" model="pcie-root"/>
    <controller type="pci" index="1" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="1" port="0x10"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x02" function="0x0" multifunction="on"/>
    </controller>
    <controller type="pci" index="2" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="2" port="0x11"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x02" function="0x1"/>
    </controller>
    <controller type="pci" index="3" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="3" port="0x12"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x02" function="0x2"/>
    </controller>
    <controller type="pci" index="4" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="4" port="0x13"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x02" function="0x3"/>
    </controller>
    <controller type="pci" index="5" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="5" port="0x14"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x02" function="0x4"/>
    </controller>
    <controller type="pci" index="6" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="6" port="0x15"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x02" function="0x5"/>
    </controller>
    <controller type="pci" index="7" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="7" port="0x16"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x02" function="0x6"/>
    </controller>
    <controller type="pci" index="8" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="8" port="0x17"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x02" function="0x7"/>
    </controller>
    <controller type="pci" index="9" model="pcie-to-pci-bridge">
      <model name="pcie-pci-bridge"/>
      <address type="pci" domain="0x0000" bus="0x05" slot="0x00" function="0x0"/>
    </controller>
    <controller type="pci" index="10" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="10" port="0x18"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x03" function="0x0" multifunction="on"/>
    </controller>
    <controller type="pci" index="11" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="11" port="0x19"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x03" function="0x1"/>
    </controller>
    <controller type="pci" index="12" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="12" port="0x1a"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x03" function="0x2"/>
    </controller>
    <controller type="scsi" index="0" model="virtio-scsi">
      <address type="pci" domain="0x0000" bus="0x08" slot="0x00" function="0x0"/>
    </controller>
    <controller type="sata" index="0">
      <address type="pci" domain="0x0000" bus="0x00" slot="0x1f" function="0x2"/>
    </controller>
    <controller type="virtio-serial" index="0">
      <address type="pci" domain="0x0000" bus="0x0c" slot="0x00" function="0x0"/>
    </controller>
    <filesystem type="mount" accessmode="passthrough">
      <driver type="virtiofs"/>
      <source dir="/home/nemu/Downloads"/>
      <target dir="nemu_downloads"/>
      <address type="pci" domain="0x0000" bus="0x04" slot="0x00" function="0x0"/>
    </filesystem>
    <interface type="bridge">
      <mac address="52:54:00:cc:75:be"/>
      <source bridge="vmbr0"/>
      <model type="virtio"/>
      <link state="up"/>
      <address type="pci" domain="0x0000" bus="0x01" slot="0x00" function="0x0"/>
    </interface>
    <interface type="bridge">
      <mac address="52:54:00:b8:8d:30"/>
      <source bridge="vmbr1"/>
      <model type="virtio"/>
      <address type="pci" domain="0x0000" bus="0x07" slot="0x00" function="0x0"/>
    </interface>
    <channel type="spicevmc">
      <target type="virtio" name="com.redhat.spice.0"/>
      <address type="virtio-serial" controller="0" bus="0" port="1"/>
    </channel>
    <input type="mouse" bus="virtio">
      <address type="pci" domain="0x0000" bus="0x0a" slot="0x00" function="0x0"/>
    </input>
    <input type="keyboard" bus="virtio">
      <address type="pci" domain="0x0000" bus="0x0b" slot="0x00" function="0x0"/>
    </input>
    <input type="mouse" bus="ps2"/>
    <input type="keyboard" bus="ps2"/>
    <graphics type="spice" port="-1" autoport="no" listen="127.0.0.1">
      <listen type="address" address="127.0.0.1"/>
      <image compression="off"/>
      <gl enable="no"/>
    </graphics>
    <sound model="ich9">
      <audio id="1"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x1b" function="0x0"/>
    </sound>
    <audio id="1" type="spice"/>
    <video>
      <model type="vga" vram="16384" heads="1" primary="yes">
        <acceleration accel3d="no"/>
      </model>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x01" function="0x0"/>
    </video>
    <hostdev mode="subsystem" type="pci" managed="yes">
      <source>
        <address domain="0x0000" bus="0x04" slot="0x00" function="0x0"/>
      </source>
      <address type="pci" domain="0x0000" bus="0x03" slot="0x00" function="0x0"/>
    </hostdev>
    <hostdev mode="subsystem" type="pci" managed="yes">
      <source>
        <address domain="0x0000" bus="0x04" slot="0x00" function="0x1"/>
      </source>
      <address type="pci" domain="0x0000" bus="0x06" slot="0x00" function="0x0"/>
    </hostdev>
    <redirdev bus="usb" type="spicevmc">
      <address type="usb" bus="0" port="2"/>
    </redirdev>
    <redirdev bus="usb" type="spicevmc">
      <address type="usb" bus="0" port="3"/>
    </redirdev>
    <redirdev bus="usb" type="spicevmc">
      <address type="usb" bus="0" port="4"/>
    </redirdev>
    <redirdev bus="usb" type="spicevmc">
      <address type="usb" bus="0" port="5"/>
    </redirdev>
    <watchdog model="itco" action="reset"/>
    <memballoon model="none"/>
  </devices>
  <qemu:commandline>
    <qemu:arg value="-device"/>
    <qemu:arg value="{&quot;driver&quot;:&quot;ivshmem-plain&quot;,&quot;id&quot;:&quot;shmem1&quot;,&quot;memdev&quot;:&quot;looking-glass&quot;}"/>
    <qemu:arg value="-object"/>
    <qemu:arg value="{&quot;qom-type&quot;:&quot;memory-backend-file&quot;,&quot;id&quot;:&quot;looking-glass&quot;,&quot;mem-path&quot;:&quot;/dev/kvmfr0&quot;,&quot;size&quot;:134217728,&quot;share&quot;:true}"/>
  </qemu:commandline>
</domain>
```

If more logs are needed please just ask. I will gladly provide them.