I'm running a server with QEMU emulator version 2.9.0. Although i gave the machine plenty RAM it begins segfaulting some processes after some hours which ends in a complete crash.
I can't see something special in the log when the segfaults begins.
2017-07-28 11:45:01.027+0000: starting up libvirt version: 3.5.0, qemu version: 2.9.0, hostname: htpc.lan
LC_ALL=C PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin QEMU_AUDIO_DRV=spice /usr/bin/qemu-system-x86_64 -name guest=server,debug-threads=on -S -object secret,id=masterKey0,format=raw,file=/var/lib/libvirt/qemu/domain-1-server/master-key.aes -machine pc-i440fx-2.9,accel=kvm,usb=off,dump-guest-core=off -cpu host -m 8192 -realtime mlock=off -smp 4,sockets=4,cores=1,threads=1 -uuid 5329bfd3-b947-473b-9880-d95b4ca78f28 -no-user-config -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/domain-1-server/monitor.sock,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc,driftfix=slew -global kvm-pit.lost_tick_policy=delay -no-hpet -no-shutdown -global PIIX4_PM.disable_s3=1 -global PIIX4_PM.disable_s4=1 -boot strict=on -device ich9-usb-ehci1,id=usb,bus=pci.0,addr=0x9.0x7 -device ich9-usb-uhci1,masterbus=usb.0,firstport=0,bus=pci.0,multifunction=on,addr=0x9 -device ich9-usb-uhci2,masterbus=usb.0,firstport=2,bus=pci.0,addr=0x9.0x1 -device ich9-usb-uhci3,masterbus=usb.0,firstport=4,bus=pci.0,addr=0x9.0x2 -device ahci,id=sata0,bus=pci.0,addr=0x6 -device virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x5 -drive file=/mnt/htpc/windows/VM/disks/qcow2/server-boot.qcow2,format=qcow2,if=none,id=drive-virtio-disk0 -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0xa,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1 -drive file=/dev/sda,format=raw,if=none,id=drive-virtio-disk1 -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0xb,drive=drive-virtio-disk1,id=virtio-disk1 -netdev tap,fd=24,id=hostnet0,vhost=on,vhostfd=26 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:12:34:56,bus=pci.0,addr=0x3 -spice port=5900,addr=127.0.0.1,disable-ticketing,image-compression=off,seamless-migration=on -device qxl-vga,id=video0,ram_size=67108864,vram_size=67108864,vram64_size_mb=0,vgamem_mb=16,max_outputs=1,bus=pci.0,addr=0x2 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x8 -msg timestamp=on
2017-07-28 11:45:01.032+0000: Domain id=1 is tainted: host-cpu
2017-07-28 18:55:28.270+0000: shutting down, reason=crashed
OK, i think it was my mistake. The VM accidently used the same swap partition as the host.