Re: Vga passthrough to KVM Guest issues

Max Schettler
2013-11-01T16:35:47Z

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Hey Joerg,

Am Freitag, den 01.11.2013, 16:09 +0100 schrieb Joerg Roedel:
> Hey Max,
>
> On Mon, Oct 28, 2013 at 10:17:19AM -0600, Alex Williamson wrote:
> > On Wed, 2013-10-16 at 21:08 +0200, Max Schettler wrote:
> > > Hi guys,
> > >
> > > Im trying to set up vga passthrough. I use the latest mainline kernel
> > > (3.12rc5) and patched qemu (1.6.50). When i try to start a VM using this
> > > command:
> > >
> > > qemu-system-x86_64 -enable-kvm -M q35 -m 1024 -cpu qemu64
> > > -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=06:00.0,bus=root.1,multifunction=on,x-vga=on
> > > -device vfio-pci,host=06:00.1,bus=root.1
> > >
> > > The screen attached to the passthroughed GPU turns on but does not show
> > > any output.
> > > Also I get some warnings from amd_iommu and my kernel messages are full
> > > of AMD-Vi messages:
> > > "AMD-Vi: Completion-Wait loop timed out" and
> > > "AMD-Vi: Event logged [IOTLB_INV_TIMEOUT device=06:00.0
> > > address=0x0000000438544b90"
> > >
> > > If i dont stop the qemu process this eventually forces me to reboot
> > > since the host gets unusable.
> > >
> > > I uploaded the whole dmesg output, if its of any help here:
> > > http://pastebin.com/ki13dqEd
> > >
> > > My hardware is an AMD FX-8350 with an Gigabyte 970A-UD3 and a Gigabyte
> > > 7870OC.
> > >
> > > Any help is much appreciated, thanks in advance!
>
> That's interesting, what GPU is it that you are trying to pass through
> to the guest? It seems to be an ATS capable device. Either there is a
> problem in the AMD IOMMU driver with handling ATS or there is a problem
> with the hardware and ATS should not be enabled there. Either way, the
> fix/workaround has to be in the AMD IOMMU driver.
>
>
> Joerg

I fixed this issue in the meanwhile by switching to another Mainboard,
so I guess it was at least somehow associated with the Hardware.

The first Setup was this one:
AMD FX-8350
Gigabyte 970A-UD3
Gigabyte 7870GHz Edition
Sapphire 6450

I switched to an Asrock 990FX Extreme3.