vga passthrough // vfio // qemu bridge

[Martin Wolf <mwolf@adiumentum.com>]

Early 2012 i tested the old vga passthrough capabilities of KVM and was
partly successful.
now with the new vfio driver i tried again according to alex's hints and
this guide:
https://bbs.archlinux.org/viewtopic.php?id=162768

since im primarily using ubuntu i used the daily build of saucy.
it ships qemu 1.5 and seabios 1.7.3 so the requirements are met.

according to the guide i prepared the vga card (amd 7870)

[    0.000000] Command line: BOOT_IMAGE=/boot/vmlinuz-3.10.0-2-generic
root=UUID=26fed560-a972-499d-ab14-7fec6439fd3d ro intel_iommu=on
pci-stub.ids=1002:6818,1002:aab0 quiet splash vt.handoff=7
[    0.000000] Kernel command line:
BOOT_IMAGE=/boot/vmlinuz-3.10.0-2-generic
root=UUID=26fed560-a972-499d-ab14-7fec6439fd3d ro intel_iommu=on
pci-stub.ids=1002:6818,1002:aab0 quiet splash vt.handoff=7
[    0.569977] pci-stub: add 1002:6818 sub=FFFFFFFF:FFFFFFFF
cls=00000000/00000000
[    0.569987] pci-stub 0000:01:00.0: claimed by stub
[    0.569994] pci-stub: add 1002:AAB0 sub=FFFFFFFF:FFFFFFFF
cls=00000000/00000000
[    0.569998] pci-stub 0000:01:00.1: claimed by stub

then did this just to be sure:
echo "options vfio_iommu_type1 allow_unsafe_interrupts=1" >
/etc/modprobe.d/vfio_iommu_type1.conf
(or was that wrong?)
im using a z87 haswell mainboard

after that i binded the two devices to vfio-pci with:
vfio-bind 0000:01:00.0 0000:01:00.1 (the script in the guide)

afterwards i was able to start the kvm with
qemu-system-x86_64 -enable-kvm -M q35 -m 8192 -cpu host \
-smp 8,sockets=1,cores=4,threads=8 \
-bios /usr/share/qemu/bios.bin -vga none \
-device
ioh3420,bus=pcie.0,addr=1c.0,multifunction=on,port=1,chassis=1,id=root.1 \
-device
vfio-pci,host=01:00.0,bus=root.1,addr=00.0,multifunction=on,x-vga=on \
-device vfio-pci,host=01:00.1,bus=root.1,addr=00.1 \
-device ahci,bus=pcie.0,id=ahci \
-drive file=/home/martin/windows.img,if=none,id=disk,format=raw -device
virtio-blk-pci,drive=disk \
-drive file=/home/martin/X17-59885.iso,id=isocd -device
ide-cd,bus=ahci.0,drive=isocd \
-net nic,model=virtio \
-net user \
-usb -usbdevice host:1532:000c \
-drive file=/home/martin/Downloads/virtio-win-0.1-59.iso,id=isocd1
-device ide-cd,bus=ahci.1,drive=isocd1

to my surprise i instantly got the windows installation running
installed the virtio drivers for nic and storage
and had 15 mins later a working win7 installation.
now i installed the amd driver (13.4) and rebooted.
i got a bluescreen. similar to my old expiriences so i thought do a
clean host reboot and try again.
but still the same. so i tried to load the bios.rom for the card (found
it on techpowerup) again no luck.
maybe someone knows a hint?

-------

about qemu bridge
i tried to set up a bridge with the config but qemu always told me that
qemu-bridge-helper is not present.
all i found out that it propably got removed from the package because of
the lack of control over the tap
devices.
now my question how can i still bridge the vm into my network without
that helper?