Windows 10 VM - GTX 2070 Super passthrough only PCIE 1.1

[esierp]

Hello Guys,

 

i've got a problem with the PCI-E speed in a Windows 10 VM. 

I'm using Unraid 6.8.3, because my GPU passthrough wont work with 6.9.* or 6.10.*.

 

The graphicscard is attached to an PCI-E 3.0 x16 slot.

GPU-Z and HWInfo or similiar tools shows me that the GPU got only PCIE 1.1. (2.5 GT/s vs . 8 GT/s)

 

Benchmarked with ForzaHorizon5 ~30FPS@1080p in VM, outside VM ~60FPS@4k with similar settings.

Server is remote controlled via parsec and self installed vnc server on vm machine.

 

XML Settings from VM machine:

used an OVMF bios with i440fx-4.2 and Hyper-V on.

Reconfigured the PCI bus to the same slot with multifunction on, so that all 4 devices from GPU are passthroughed.

Installed Nvidia Geforce Driver, MSI Fix.

 

Does anyone had the same problem and a solution for it? Or some advice how this is possible to be fixed?

 

Syslinux config:

 

VMSettings Bios CPU:

 

VMSettings GPU:

 

IOMMU_Groups:

 

XML Config:

<?xml version='1.0' encoding='UTF-8'?>
<domain type='kvm' id='1'>
  <name>Windows 10 683</name>
  <uuid>d47cb08c-7c5d-50fd-b949-d07ab80918f0</uuid>
  <metadata>
    <vmtemplate xmlns="unraid" name="Windows 10" icon="windows.png" os="windows10"/>
  </metadata>
  <memory unit='KiB'>16777216</memory>
  <currentMemory unit='KiB'>16777216</currentMemory>
  <memoryBacking>
    <nosharepages/>
  </memoryBacking>
  <vcpu placement='static'>14</vcpu>
  <cputune>
    <vcpupin vcpu='0' cpuset='4'/>
    <vcpupin vcpu='1' cpuset='5'/>
    <vcpupin vcpu='2' cpuset='6'/>
    <vcpupin vcpu='3' cpuset='7'/>
    <vcpupin vcpu='4' cpuset='8'/>
    <vcpupin vcpu='5' cpuset='9'/>
    <vcpupin vcpu='6' cpuset='10'/>
    <vcpupin vcpu='7' cpuset='11'/>
    <vcpupin vcpu='8' cpuset='12'/>
    <vcpupin vcpu='9' cpuset='13'/>
    <vcpupin vcpu='10' cpuset='14'/>
    <vcpupin vcpu='11' cpuset='15'/>
    <vcpupin vcpu='12' cpuset='16'/>
    <vcpupin vcpu='13' cpuset='17'/>
  </cputune>
  <resource>
    <partition>/machine</partition>
  </resource>
  <os>
    <type arch='x86_64' machine='pc-i440fx-4.2'>hvm</type>
    <loader readonly='yes' type='pflash'>/usr/share/qemu/ovmf-x64/OVMF_CODE-pure-efi.fd</loader>
    <nvram>/etc/libvirt/qemu/nvram/d47cb08c-7c5d-50fd-b949-d07ab80918f0_VARS-pure-efi.fd</nvram>
  </os>
  <features>
    <acpi/>
    <apic/>
    <hyperv>
      <relaxed state='on'/>
      <vapic state='on'/>
      <spinlocks state='on' retries='8191'/>
      <vendor_id state='on' value='none'/>
    </hyperv>
  </features>
  <cpu mode='host-passthrough' check='none'>
    <topology sockets='1' cores='7' threads='2'/>
    <cache mode='passthrough'/>
  </cpu>
  <clock offset='localtime'>
    <timer name='hypervclock' present='yes'/>
    <timer name='hpet' present='no'/>
  </clock>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>restart</on_crash>
  <devices>
    <emulator>/usr/local/sbin/qemu</emulator>
    <disk type='file' device='disk'>
      <driver name='qemu' type='raw' cache='writeback'/>
      <source file='/mnt/user/domains/Windows 10_2070_q35/vdisk1.img' index='1'/>
      <backingStore/>
      <target dev='hdc' bus='virtio'/>
      <boot order='1'/>
      <alias name='virtio-disk2'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
    </disk>
    <controller type='usb' index='0' model='qemu-xhci' ports='15'>
      <alias name='usb'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/>
    </controller>
    <controller type='ide' index='0'>
      <alias name='ide'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>
    </controller>
    <controller type='virtio-serial' index='0'>
      <alias name='virtio-serial0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
    </controller>
    <controller type='pci' index='0' model='pci-root'>
      <alias name='pci.0'/>
    </controller>
    <interface type='bridge'>
      <mac address='52:54:00:02:4e:26'/>
      <source bridge='br0'/>
      <target dev='vnet0'/>
      <model type='virtio'/>
      <alias name='net0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
    </interface>
    <serial type='pty'>
      <source path='/dev/pts/0'/>
      <target type='isa-serial' port='0'>
        <model name='isa-serial'/>
      </target>
      <alias name='serial0'/>
    </serial>
    <console type='pty' tty='/dev/pts/0'>
      <source path='/dev/pts/0'/>
      <target type='serial' port='0'/>
      <alias name='serial0'/>
    </console>
    <channel type='unix'>
      <source mode='bind' path='/var/lib/libvirt/qemu/channel/target/domain-1-Windows 10 683/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>
    <input type='tablet' bus='usb'>
      <alias name='input0'/>
      <address type='usb' bus='0' port='1'/>
    </input>
    <input type='mouse' bus='ps2'>
      <alias name='input1'/>
    </input>
    <input type='keyboard' bus='ps2'>
      <alias name='input2'/>
    </input>
    <hostdev mode='subsystem' type='pci' managed='yes'>
      <driver name='vfio'/>
      <source>
        <address domain='0x0000' bus='0x0a' slot='0x00' function='0x0'/>
      </source>
      <alias name='hostdev0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0' multifunction='on'/>
    </hostdev>
    <hostdev mode='subsystem' type='pci' managed='yes'>
      <driver name='vfio'/>
      <source>
        <address domain='0x0000' bus='0x0a' slot='0x00' function='0x1'/>
      </source>
      <alias name='hostdev1'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x1'/>
    </hostdev>
    <hostdev mode='subsystem' type='pci' managed='yes'>
      <driver name='vfio'/>
      <source>
        <address domain='0x0000' bus='0x0a' slot='0x00' function='0x2'/>
      </source>
      <alias name='hostdev2'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x2'/>
    </hostdev>
    <hostdev mode='subsystem' type='pci' managed='yes'>
      <driver name='vfio'/>
      <source>
        <address domain='0x0000' bus='0x0a' slot='0x00' function='0x3'/>
      </source>
      <alias name='hostdev3'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x3'/>
    </hostdev>
    <memballoon model='none'/>
  </devices>
  <seclabel type='dynamic' model='dac' relabel='yes'>
    <label>+0:+100</label>
    <imagelabel>+0:+100</imagelabel>
  </seclabel>
</domain>

 

VM GPUZ/HWInfo :

 

 

[ghost82]

I had a similar issue with windows 10 bare metal installation and a nvidia gtx titan black, but in my case gpu-z was reporting it running at gen2.

1. check the bios settings and make sure the pcie slot runs at gen3, mine was already set at gen3

2. tweak the windows registry: I remember I followed the description of the second message here:

https://forums.evga.com/How-to-force-PCIE-Gen-3-in-Windows-10-m2372915.aspx

 

And after rebooting gpu-z was reporting my gpu running at gen3.

[ghost82]

I forgot one important thing!

Put load on your gpu then check in gpu-z (you can run the render inside gpu-z itself), otherwise the speed will scale down and you will always read 1.1.

I would try this before, because hwinfo is reporting correctly that the gpu is installed in a 3.0x16 slot.

Edited December 23, 2021 by ghost82

[esierp]

Thank you @ghost82, i've tried both solutions provided by you and now it returns PCIe 3.0!