[qxl] Ubuntu 24.04 VM guest console freezes after some hours

[Thomas Dreibholz]

I made simple Ubuntu 24.04 LTS Server installations as guests in an up-to-date Proxmox. No Xorg/Wayland, just CLI! The virtual graphics card is qml, 16 MiB memory (standard settings). Opening the console in the Proxmox GUI, or via remote-viewer initially is fine. However, after some time (usually: hours), the console just locks up. However, SSH into the guest machine remains fine.

Ubuntu 22.04, or 20.04 are fine, the issue only occurs with the new Ubuntu 24.04. The issue is reproducible with all Ubuntu 24.04 VMs. A reboot the the VM makes the console usable again, until the issue occurs again (usually after some hours).

Unusual observation from dmesg:
...
[522890.748557] [TTM] Buffer eviction failed
[522890.748981] qxl 0000:00:01.0: object_init failed for (4096, 0x00000001)
[522890.749336] [drm:qxl_alloc_bo_reserved [qxl]] *ERROR* failed to allocate VRAM BO
[522906.108616] [TTM] Buffer eviction failed
[522906.109045] qxl 0000:00:01.0: object_init failed for (4096, 0x00000001)
[522906.109386] [drm:qxl_alloc_bo_reserved [qxl]] *ERROR* failed to allocate VRAM BO
[522921.468729] [TTM] Buffer eviction failed
[522921.469154] qxl 0000:00:01.0: object_init failed for (4096, 0x00000001)
[522921.469512] [drm:qxl_alloc_bo_reserved [qxl]] *ERROR* failed to allocate VRAM BO
[522936.828783] [TTM] Buffer eviction failed
[522936.829207] qxl 0000:00:01.0: object_init failed for (4096, 0x00000001)
[522936.829630] [drm:qxl_alloc_bo_reserved [qxl]] *ERROR* failed to allocate VRAM BO
...

nornetpp@hansa:~$ uname -a
Linux hansa.management.crnalab.net 6.8.0-31-generic #31-Ubuntu SMP PREEMPT_DYNAMIC Sat Apr 20 00:40:06 UTC 2024 x86_64 x86_64 x86_64 GNU/Linux

nornetpp@hansa:~$ lsmod | grep qxl
qxl 86016 0
drm_ttm_helper 12288 1 qxl
ttm 110592 2 qxl,drm_ttm_helper

ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: xorg (not installed)
ProcVersionSignature: Ubuntu 6.8.0-31.31-generic 6.8.1
Uname: Linux 6.8.0-31-generic x86_64
ApportVersion: 2.28.1-0ubuntu2
Architecture: amd64
CasperMD5CheckResult: pass
Date: Wed May 8 11:05:07 2024
InstallationDate: Installed on 2024-03-12 (57 days ago)
InstallationMedia: Ubuntu-Server 24.04 LTS "Noble Numbat" - Daily amd64 (20240312)
ProcEnviron:
 LANG=en_IE.UTF-8
 LANGUAGE=nb:de:en_US
 PATH=(custom, no user)
 SHELL=/bin/bash
 TERM=xterm-256color
SourcePackage: xorg
Symptom: display
Title: Xorg freeze
UpgradeStatus: No upgrade log present (probably fresh install)

[Thomas Dreibholz (dreibh)]

I assume it is a problem in the QXL driver of the kernel used by Ubuntu 24.04.

nornetpp@hansa:~$ sudo lshw -c video
  *-display
       description: VGA compatible controller
       product: QXL paravirtual graphic card
       vendor: Red Hat, Inc.
       physical id: 1
       bus info: pci@0000:00:01.0
       logical name: /dev/fb0
       version: 05
       width: 32 bits
       clock: 33MHz
       capabilities: vga_controller bus_master rom fb
       configuration: depth=32 driver=qxl latency=0 resolution=1024,768
       resources: irq:21 memory:80000000-83ffffff memory:84000000-85ffffff memory:87244000-87245fff ioport:7120(size=32) memory:c0000-dffff

[Thomas Dreibholz (dreibh)]

The issue is most likely *not* an Xorg bug, since Xorg is not installed on the affected systems. Also, Wayland is not installed as well.

The code causing the error message in "dmesg" is in the kernel, drivers/gpu/drm/qxl/qxl_cmd.c, qxl_alloc_bo_reserved().