WARNING on boot in Intel GVT-g guest

[Leonardo Müller]

When booting Ubuntu Cosmic Cuttlefish 18.10 in an Intel GVT-g Virtual Machine, a kernel WARNING appears in dmesg, with the following:

[ 3.563734] WARNING: CPU: 3 PID: 346 at drivers/gpu/drm/i915/i915_irq.c:161 gen3_assert_iir_is_zero+0x38/0xa0 [i915]

I have not noticed negative effects in the VM, but a kernel WARNING probably has relevance.

While I added a custom EDID to fix resolution, the WARNING happens without custom EDID set too. I will add information about the host in the next message.

ProblemType: Bug
DistroRelease: Ubuntu 18.10
Package: linux-image-4.18.0-10-generic 4.18.0-10.11
ProcVersionSignature: User Name 4.18.0-10.11-generic 4.18.12
Uname: Linux 4.18.0-10-generic x86_64
ApportVersion: 2.20.10-0ubuntu13
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC1: ubuntu 1896 F.... pulseaudio
CurrentDesktop: ubuntu:GNOME
Date: Sun Oct 21 19:44:44 2018
InstallationDate: Installed on 2018-10-18 (3 days ago)
InstallationMedia: Ubuntu 18.10 "Cosmic Cuttlefish" - Release amd64 (20181017.3)
IwConfig:
 lo no wireless extensions.

 ens8 no wireless extensions.
Lsusb:
 Bus 003 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
 Bus 002 Device 003: ID 46f4:0002
 Bus 002 Device 002: ID 0627:0001 Adomax Technology Co., Ltd
 Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
 Bus 001 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
MachineType: QEMU Standard PC (i440FX + PIIX, 1996)
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.18.0-10-generic root=UUID=6cb7fc66-eb2c-4203-9d7d-2aa2665911ac ro quiet splash drm.edid_firmware=EDID_E1941.bin log_buf_len=16M vt.handoff=1
RelatedPackageVersions:
 linux-restricted-modules-4.18.0-10-generic N/A
 linux-backports-modules-4.18.0-10-generic N/A
 linux-firmware 1.175
RfKill:

SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 02/06/2015
dmi.bios.vendor: EFI Development Kit II / OVMF
dmi.bios.version: 0.0.0
dmi.chassis.type: 1
dmi.chassis.vendor: QEMU
dmi.chassis.version: pc-i440fx-3.0
dmi.modalias: dmi:bvnEFIDevelopmentKitII/OVMF:bvr0.0.0:bd02/06/2015:svnQEMU:pnStandardPC(i440FX+PIIX,1996):pvrpc-i440fx-3.0:cvnQEMU:ct1:cvrpc-i440fx-3.0:
dmi.product.name: Standard PC (i440FX + PIIX, 1996)
dmi.product.version: pc-i440fx-3.0
dmi.sys.vendor: QEMU

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This change was made by a bot.

[Leonardo Müller (leozinho29-eu)]

Host information:

OS: Xubuntu 18.04.1 (amd64);
Kernel: 4.17.19 with 337fe9f5c1e7de1f391c6a692531379d2aa2ee11 applied to fix https://bugs.freedesktop.org/show_bug.cgi?id=107899;
QEMU: 3.0.0;

QEMU command line:

env PULSE_LATENCY_MSEC=5 QEMU_AUDIO_ADC_VOICES=0 QEMU_AUDIO_DRV=pa qemu-system-x86_64 \
-name "Ubuntu Cosmic" -k pt-br -nodefaults -enable-kvm -cpu host -smp cores=2,threads=2 -m 2G \
-device vfio-pci,sysfsdev=/sys/bus/pci/devices/0000:00:02.0/ef5f4cb6-734b-11e8-aaff-9fff2622012e,rombar=0,display=on,x-intx-mmap-timeout-ms=0x200,addr=0x3,id=iHD520 \
-device qemu-xhci,id=xhcihub -device usb-tablet,id=usbtablet -device usb-audio,id=usbaudio,buffer=6144 -bios /usr/share/ovmf/OVMF.fd \
-display gtk,gl=on -hda ubuntucosmic.qcow2 -monitor vc -serial mon:stdio \
-machine kernel_irqchip=on -global PIIX4_PM.disable_s3=1 -global PIIX4_PM.disable_s4=1 -M pc,usb=true \
-netdev user,id=net0,hostfwd=::5454-:22 -device e1000,netdev=net0,addr=8

[Cristian Aravena Romero (caravena)]

Did this issue start happening after an update/upgrade? Was there a
prior kernel version where you were not having this particular problem?

Would it be possible for you to test the latest upstream kernel? Refer
to https://wiki.ubuntu.com/KernelMainlineBuilds . Please test the latest
v4.19 kernel[0].

If this bug is fixed in the mainline kernel, please add the following
tag 'kernel-fixed-upstream'.

If the mainline kernel does not fix this bug, please add the tag:
'kernel-bug-exists-upstream'.

Once testing of the upstream kernel is complete, please mark this bug as
"Confirmed".

Thanks in advance.

[0] http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.19-rc8

[Leonardo Müller (leozinho29-eu)]

dmesg with 4.19.0-041900-generic is attached. 4.19-rc8 has the same WARNING on boot.

[Leonardo Müller (leozinho29-eu)]

What causes this WARNING is the host kernel.

Using latest drm-tip (d63c50f2b014037b43c1c0f108c61e0a31ede3c1) in the host, there is no WARNING in the guest, while the WARNING happens when the host uses 4.18.0-12 (HWE 18.04 Edge). 4.15.0-42 does not support iGVT-g with dma-buf, so it's not useful to test.

It seems the results weren't dependent of the Linux kernel version on the guest: they were the same with 4.18.0-11, 4.18.0-12 and 4.19.5.