3

I want to try PCI passthrough. I have passed an old capture video card to a Windows XP guest.

IOMMU is enabled;
vfio_pci is loaded

I run this command:

virsh nodedev-detach pci_0000_05_05_0

lspci -s 00:05 -v

It reports vfio is "running" the PCI device, but when I start XP with PCI devices, it gives me back this error:

Please ensure all devices within the iommu_group are bound to their vfio bus driver.

What did I get wrong?

1 Answer 1

5

I found the solution. First the IOMMU group must be identified; in my case is 11(I found it using lspci and reading pci address,in my case it is 05:05:0)

find /sys/kernel/iommu_groups/ -type l|grep \/11
/sys/kernel/iommu_groups/11/devices/0000:00:14.4
/sys/kernel/iommu_groups/11/devices/0000:05:06.0
/sys/kernel/iommu_groups/11/devices/0000:05:05.0

So we have to add 05:05 and 05:06 (the two PCI cards of the group) to qemu,with libvirt. This is easy using virt-manager add hardware, selecting pci host. Now we boot and..another error appears in dmesg:

"Flags mismatch irq 21. 00000000 (vfio-intx(0000:05:05.0)) vs. 0000000....usb...."

This means our system cannot share interrupts, so we have to remove the device from the host.

So we have to find the interrupts:

cat /proc/interrupts | grep 21

It return for example usb2, so we search for usb dir:

find  /sys/devices/pci0000\:00/0000\:00\:* -iname usb2

,go to usb dir,in my case 13.2:

cd /sys/devices/pci0000\:00/0000\:00\:13.2/

and remove(sic!) from the host:

echo -n 1 > remove

Now when starting the guest,the pci cards are assigned to it.

And for return to us? I will add answer...if I find the solution!

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.