I finally got my VM working with PCI passthrough for an nVidia card and a PCI-E USB controller card. So far, no problems. Thank you Alex for all your wonderful blog and forum posts. The use of TightVNC was invaluable. My last niggling problem is automating two commands:
echo "0000:04:00.0" > /sys/bus/pci/devices/0000:04:00.0/driver/unbind
echo 0x1912 0x0014 > /sys/bus/pci/drivers/vfio-pci/new_id
I currently type them when the host system boots. I tried putting them in a /sbin/vfio-pci-override-usb.sh script referenced in the /etc/dracut.conf.d/local.conf file with the line:
However, the kernel drive in use is still xhci_hcd, not vfio-pci, as it is after invoking the above two commands. Where should these commands go to get executed at boot? Thank you.
On 01/19/2016 03:21 AM, thibaut noah wrote:
Update note, i found what prevent my card from running, basically i need to reboot without anything plug into the card and then i can unbind and rebind the card, what that strange behaviour?
2016-01-19 11:35 GMT+01:00 thibaut noah <thibaut noah gmail com>:
Bumping this, running virsh nodedev-detach pci_0000_xx_yy_z' (with proper numbers) and/or having managed=yes in the xml file changes nothing (actually i had this already), ovmf still hangs waiting for i have no idea what.
Cannot run by unbinding the device through script either, seems that i was lucky, or maybe i did something that i forgot.
Tried to add nodedev-detach to modprobe but it seems that i did not do it in the proper way so it wasn't working
2016-01-16 11:30 GMT+01:00 thibaut noah <thibaut noah gmail com>:
Didn't know libvirt was capable of unbinding devices on its own, good to know, i'm gonna try this and if i manage to make it work i don't have any reason to bother myself more with this. (note that i don't use virt-manager since you advise me to use libvirt directly)
Though the usb card will only be use by the vm, i have more than enough usb ports on my backpanel.
Tried the gpu method by adding the id of the device in modprobe.d after gpu's ids but it didn't work.
I paid it 50euros :(
Thanks for the explanations alex
2016-01-15 18:59 GMT+01:00 Alex Williamson <alex williamson redhat com>:
A couple comments, first, boot time pre-binding to vfio-pci is really
only necessary for devices where the native host drivers behave poorly
if you take the device away from them later. This is why we do it for
GPUs and their companion sound device, host GPU drivers don't like to
give up the device, it plays poorly with any sort of graphics on the
host, and sequestering the audio device prevents host tools from
getting confused (and there are some bugs in the audio driver limiting
number of attach/detach cycles iirc).
For anything else, you can dynamically unbind the device from the host
driver, bind it to vfio while the VM is running, and give it back to
the host on shutdown. libvirt will do this automatically for you if
your XML sets managed='yes' for the <hostdev> device. This is the default, so if you use virt-manager to add the device, just select Add Hardware -> PCI Host Device -> select device -> Finish. Done. If for some reason you don't want the device flopping back and forth between host and guest, just run 'virsh nodedev-detach pci_0000_xx_yy_z' at bootup where xx_yy_z is the PCI bus (xx), device (yy), and function (z) numbers, the same as in lspci. You can adopt some of the GPU methods for doing this if you want it to happen earlier as well, there are lots of ways to do this with modprobe.d (install options, softdep, etc..)
Finally, yes I've seen OVMF hang with some crappy USB controllers. I'm
not sure if it's dependent on the devices attached or the controller
itself, but cheaper isn't always better when it comes to selecting
devices to use with device assignment. Thanks,
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