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Libvirt Fails to Use GVT-G Device (iommu_group: No such file or directory)

asked 2019-02-14 21:25:31 -0500

CuriousTommy gravatar image

updated 2019-02-15 10:37:37 -0500

Hello everyone,

In the past, I was able to get GVT-G to work my Dell Precision 5510 laptop using this guide; however, I had to reinstall Fedora (29) for stability reasons. After I reimported the XML virtual machine file into libvirt, I keep getting this error:

Error starting domain: internal error: Process exited prior to exec: libvirt:  error : failed to access '/sys/bus/mdev/devices/fff6f017-3417-4ad3-b05e-17ae3e1a4615/iommu_group': No such file or directory

Traceback (most recent call last):
  File "/usr/share/virt-manager/virtManager/asyncjob.py", line 75, in cb_wrapper
    callback(asyncjob, *args, **kwargs)
  File "/usr/share/virt-manager/virtManager/asyncjob.py", line 111, in tmpcb
    callback(*args, **kwargs)
  File "/usr/share/virt-manager/virtManager/libvirtobject.py", line 66, in newfn
    ret = fn(self, *args, **kwargs)
  File "/usr/share/virt-manager/virtManager/domain.py", line 1420, in startup
    self._backend.create()
  File "/usr/lib64/python3.7/site-packages/libvirt.py", line 1080, in create
    if ret == -1: raise libvirtError ('virDomainCreate() failed', dom=self)
libvirt.libvirtError: internal error: Process exited prior to exec: libvirt:  error : failed to access '/sys/bus/mdev/devices/fff6f017-3417-4ad3-b05e-17ae3e1a4615/iommu_group': No such file or directory

At first, I thought I didn't enable intel_iommu, but the grub file shows that I do have it enabled. Plus, I do get a readout of all of the IOMMU groups (by using the Arch Linux script). I also manually created the vgpu (otherwise I would get a different error).

Does anyone know what I am doing wrong here? You can find my xmldump of my windows 10 VM here.


Edit: To clarify, the mdev device does exist, but for some reason iommu_group does not exist in the drive's folder. I used the following command to create the device:

echo fff6f017-3417-4ad3-b05e-17ae3e1a4615 | sudo tee /sys/bus/pci/devices/0000:00:02.0/mdev_supported_types/i915-GVTg_V5_8/create

If the UUIDs were different, I should be getting this error instead:

Error starting domain: device not found: mediated device 'fff6f017-3417-4ad3-b05e-17ae3e1a4615' not found

Traceback (most recent call last):
  File "/usr/share/virt-manager/virtManager/asyncjob.py", line 75, in cb_wrapper
    callback(asyncjob, *args, **kwargs)
  File "/usr/share/virt-manager/virtManager/asyncjob.py", line 111, in tmpcb
    callback(*args, **kwargs)
  File "/usr/share/virt-manager/virtManager/libvirtobject.py", line 66, in newfn
    ret = fn(self, *args, **kwargs)
  File "/usr/share/virt-manager/virtManager/domain.py", line 1420, in startup
    self._backend.create()
  File "/usr/lib64/python3.7/site-packages/libvirt.py", line 1080, in create
    if ret == -1: raise libvirtError ('virDomainCreate() failed', dom=self)
libvirt.libvirtError: device not found: mediated device 'fff6f017-3417-4ad3-b05e-17ae3e1a4615' not found
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Comments

If anyone else is running into the same problem, you can find the solution here: https://github.com/intel/gvt-linux/is...

CuriousTommy gravatar imageCuriousTommy ( 2019-03-14 18:31:14 -0500 )edit

1 Answer

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answered 2019-02-15 06:34:11 -0500

Aeyoun gravatar image

updated 2019-02-15 06:37:51 -0500

The first error message says what's wrong: you're missing a block disk device. I'll assume you removed this device and repurposed the disks when you reinstalled your system.

You'll need to remove or update the reference to that disk in your configuration file. You can see the mdev's UUID referenced as a <hostdev> in your configuration.

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Comments

Since I have to manually create the vgpu for every reboot (or cold bootup), I always use this command. I am pretty sure the UUIDs are the same.

echo fff6f017-3417-4ad3-b05e-17ae3e1a4615 | sudo tee /sys/bus/pci/devices/0000:00:02.0/mdev_supported_types/i915-GVTg_V5_8/create
CuriousTommy gravatar imageCuriousTommy ( 2019-02-15 10:28:45 -0500 )edit

Plus the mdev devices does exist

$ /sys/bus/mdev/devices/fff6f017-3417-4ad3-b05e-17ae3e1a4615/
bash: /sys/bus/mdev/devices/fff6f017-3417-4ad3-b05e-17ae3e1a4615/: Is a directory

But for some reason, iommu_group does not exist here

$ cd /sys/bus/mdev/devices/fff6f017-3417-4ad3-b05e-17ae3e1a4615/
$ ls
intel_vgpu  mdev_type  power  remove  subsystem  uevent
CuriousTommy gravatar imageCuriousTommy ( 2019-02-15 10:29:25 -0500 )edit

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Asked: 2019-02-14 21:25:31 -0500

Seen: 51 times

Last updated: Feb 15