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?
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!
