iGVT-g guest freezes if idle for too long

[Leonardo Müller]

A Windows 10 iGVT-g guest is crashing if left idle for too long. "Too long" can mean hours or even minutes with no load. The QEMU command line is:

/usr/bin/qemu-system-x86_64 -name Windows 10 -nodefaults -M pc,usb=true -machine kernel_irqchip=on -enable-kvm -mem-prealloc -mem-path /dev/hugepages/qemu -device qemu-xhci,id=qemu-xhci,addr=4,p2=15,p3=15,streams=on,command_serr_enable=on -global PIIX4_PM.disable_s3=1 -global PIIX4_PM.disable_s4=1 -drive file=./images/redm.qcow2,if=virtio -cpu host -smp sockets=1,cores=2,threads=1 -m
 8192M -bios /usr/share/seabios/bios.bin -device usb-tablet,id=tablet,bus=qemu-xhci.0,port=1 -vga none -monitor vc -serial stdio -display gtk,gl=on -device vfio-pci-nohotplug,sysfsdev=/sys/bus/pci/devices/0000:00:02.0/20312cec-80f4-448a-9f09-7b93adbf672c,x-igd-opregion=on,display=on,addr=0x3,rombar=0,id=iHD520,ramfb=on -device ivshmem-plain,memdev=HMB -object memory-backend-file,id=HMB,size=4M,mem-path=/dev/shm/test,share=on -netdev user,id=net0,hostfwd=::33890-:3389,smb=./TOSHIBA2TB/ -device virtio-net-pci,netdev=net0,id=n0,addr=0x8 -monitor telnet:127.0.0.1:55555,server,nowait

Normally, I use the machine pc-i440fx-3.1 but I set the latest one (pc, or pc-i440fx-4.2) for testing, which didn't fix this freeze.

In this state, it's not possible to reclaim the memory and the virtual GPU, they are stuck until the computer is powered off. After this QEMU guest freeze, it is impossible to power off the computer cleanly: it's required to forcefully shutdown, as the system fails to

The telnet server from the guest still connect, but doesn't respond.

I installed the OEM kernel to get the 5.14 version of the kernel. Testing with drm-tip (commit 7c36ed237585ed2f645439e62dafccac070d5e33, from August), I was able to left the guest idle for hours with no problem multiple times, but using Ubuntu's generic (5.4, 5.8, 5.11) or oem (5.14) kernel this freeze is happening.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: linux-image-5.14.0-1004-oem 5.14.0-1004.4
ProcVersionSignature: Ubuntu 5.14.0-1004.4-oem 5.14.5
Uname: Linux 5.14.0-1004-oem x86_64
ApportVersion: 2.20.11-0ubuntu27.20
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: XFCE
Date: Wed Oct 6 21:33:41 2021
InstallationDate: Installed on 2017-06-13 (1576 days ago)
InstallationMedia: Xubuntu 17.04 "Zesty Zapus" - Release amd64 (20170412)
SourcePackage: linux-signed-oem-5.14
UpgradeStatus: Upgraded to focal on 2019-12-22 (654 days ago)
modified.conffile..etc.cron.daily.apport: [deleted]