[vfio-users] Switching to Q35

[Kővágó Zoltán]

On 2018-12-29 16:31, Alex Williamson wrote:
> Use virtual machine manager again to create a Q35 VM and re-use your
> disk image.  Note that this is the same as moving your disk from one
> machine to another with potentially different disk and network
> controllers.  If you're using virtio for both, you're probably fine
> otherwise you might need to go back to the 440fx machine type and
> install extra drivers to make it work.  Also be sure to maintain the
> same firmware type in the VM, SeaBIOS or OVMF.  Switching between the
> two for an existing VM image is non-trivial.  Thanks,

Hi,

Reading this thread I decided to try the switch. Since life is too short
to figure out libvirt, I'm running qemu directly, so I just added -M q35
and staryed my win8.1 vm and it worked, except, of course, the nvidia
driver.

Looking at the device manager, on one vm it reverted to the standard vga
driver, while on the other it displays my gpu as unknown device without
a driver (but it displays the desktop on this unknown device!).
If I select update driver, or try to manually reinstall the nvidia
driver, I hear that device connected/reconnected sound, the screen turns
off, then a few seconds later the vm just reboots.

Any idea what is the problem? Did anyone try this configuration? (OVMF +
win8.1 x64 + nvidia gtx980 passthrough)

My qemu command line is something like this
-M q35 -enable-kvm -m 4096 -cpu
host,kvm=off,hv_time,hv_vendor_id=fuck_nvidia,hv_relaxed,hv_vapic,hv_spinlocks=0x1fff
-smp cores=3,threads=2,sockets=1 -nodefaults -rtc base=localtime
--device virtio-balloon -realtime '' -device piix4-usb-uhci,id=uhci -qmp
unix:/tmp/qemu-passthrough,server,nowait -drive
file=/dev/nullptr-vg/win81_tmp,id=disk,format=raw,discard=unmap,cache=unsafe,if=none
-device virtio-scsi-pci,id=scsi -device scsi-hd,drive=disk,id=scsi-disk
-drive if=pflash,format=raw,readonly,file=/home/dirty_ice/OVMF_CODE.fd
-drive if=pflash,format=raw,file=/home/dirty_ice/OVMF_VARS81.fd -netdev
bridge,id=mynet
-device virtio-net,netdev=mynet,id=mynic,mac=52:d0:91:a8:08:0e -display
none -monitor stdio -device
vfio-pci,host=02:00.0,addr=07.0,multifunction=on,id=vga -device
vfio-pci,host=02:00.1,addr=07.1,id=vga-hdmi
-audiodev
alsa,id=foo,out.mixeng=off,alsa-out.try-poll=off,threshold=15000,timer-period=5000,alsa-out.dev=swap
-device usb-audio,audiodev=foo,multi=on,buffer=10752,id=audio -drive
file=/dev/nullptr-vg/win81_exttest,id=diskext,format=raw,discard=unmap,if=none
-device scsi-hd,drive=diskext,id=scsi-diskext

(Yes, I know, I should switch from piix4-usb-uhci to qemu-xhci, but
usb-audio has problems with it)

Regards,
Zoltan