Description of problem:
I had a virtual machine created using virt-manager with chipset pc-i440fx-2.0. I used the command line below to create another VM using Q35:
virt-install --name=Win8Q35 --ram=8192 --machine=q35 --cpu host --os-type=windows --os-variant=win7 --boot hd,menu=on --vcpus=4,cores=2,threads=2 --graphics spice --watchdog default --disk path=/dev/sdb --host-device pci_0000_00_1b_0 --host-device pci_0000_00_1a_0 --host-device pci_0000_01_00_0 --host-device pci_0000_01_00_1 --serial pty --console pty,target_type=virtio

When the virtual machine boots up, windows 8 starts to load but a BSOD appears (with pc-i440fx, no bsod happened). Then the VM shuts down and this exception shows up.

VM Details:
<domain type='kvm'>
  <name>Win8Q35</name>
  <uuid>2d5506dc-5fa8-4857-a457-a82eb647243d</uuid>
  <memory unit='KiB'>8388608</memory>
  <currentMemory unit='KiB'>8388608</currentMemory>
  <vcpu placement='static' current='1'>4</vcpu>
  <os>
    <type arch='x86_64' machine='pc-q35-2.0'>hvm</type>
    <boot dev='hd'/>
    <bootmenu enable='yes'/>
  </os>
  <features>
    <acpi/>
    <apic/>
    <pae/>
  </features>
  <cpu mode='custom' match='exact'>
    <model fallback='allow'>Haswell</model>
    <vendor>Intel</vendor>
    <topology sockets='1' cores='2' threads='2'/>
    <feature policy='require' name='tm2'/>
    <feature policy='require' name='est'/>
    <feature policy='require' name='vmx'/>
    <feature policy='require' name='osxsave'/>
    <feature policy='require' name='smx'/>
    <feature policy='require' name='ss'/>
    <feature policy='require' name='ds'/>
    <feature policy='require' name='vme'/>
    <feature policy='require' name='dtes64'/>
    <feature policy='require' name='abm'/>
    <feature policy='require' name='ht'/>
    <feature policy='require' name='acpi'/>
    <feature policy='require' name='pbe'/>
    <feature policy='require' name='tm'/>
    <feature policy='require' name='pdcm'/>
    <feature policy='require' name='pdpe1gb'/>
    <feature policy='require' name='ds_cpl'/>
    <feature policy='require' name='rdrand'/>
    <feature policy='require' name='f16c'/>
    <feature policy='require' name='xtpr'/>
    <feature policy='require' name='monitor'/>
  </cpu>
  <clock offset='localtime'>
    <timer name='rtc' tickpolicy='catchup'/>
    <timer name='pit' tickpolicy='delay'/>
    <timer name='hpet' present='no'/>
  </clock>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>restart</on_crash>
  <devices>
    <emulator>/usr/bin/qemu-kvm</emulator>
    <disk type='block' device='disk'>
      <driver name='qemu' type='raw' cache='none' io='native'/>
      <source dev='/dev/sdb'/>
      <target dev='vda' bus='virtio'/>
      <address type='pci' domain='0x0000' bus='0x02' slot='0x0b' function='0x0'/>
    </disk>
    <disk type='file' device='cdrom'>
      <driver name='qemu' type='raw'/>
      <source file='/Storage/Data/My Softwares/SO Images/Windows/Windows81PRO.iso'/>
      <target dev='hda' bus='ide'/>
      <readonly/>
      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
    </disk>
    <controller type='usb' index='0' model='ich9-ehci1'>
      <address type='pci' domain='0x0000' bus='0x02' slot='0x03' function='0x7'/>
    </controller>
    <controller type='usb' index='0' model='ich9-uhci1'>
      <master startport='0'/>
      <address type='pci' domain='0x0000' bus='0x02' slot='0x03' function='0x0' multifunction='on'/>
    </controller>
    <controller type='usb' index='0' model='ich9-uhci2'>
      <master startport='2'/>
      <address type='pci' domain='0x0000' bus='0x02' slot='0x03' function='0x1'/>
    </controller>
    <controller type='usb' index='0' model='ich9-uhci3'>
      <master startport='4'/>
      <address type='pci' domain='0x0000' bus='0x02' slot='0x03' function='0x2'/>
    </controller>
    <controller type='sata' index='0'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x1f' function='0x2'/>
    </controller>
    <controller type='pci' index='0' model='pcie-root'/>
    <controller type='pci' index='1' model='dmi-to-pci-bridge'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x1e' function='0x0'/>
    </controller>
    <controller type='pci' index='2' model='pci-bridge'>
      <address type='pci' domain='0x0000' bus='0x01' slot='0x01' function='0x0'/>
    </controller>
    <controller type='ide' index='0'/>
    <controller type='virtio-serial' index='0'>
      <address type='pci' domain='0x0000' bus='0x02' slot='0x04' function='0x0'/>
    </controller>
    <interface type='bridge'>
      <mac address='52:54:00:1d:c7:48'/>
      <source bridge='bridge0'/>
      <model type='virtio'/>
      <address type='pci' domain='0x0000' bus='0x02' slot='0x01' function='0x0'/>
    </interface>
    <interface type='network'>
      <mac address='52:54:00:54:2a:c6'/>
      <source network='Isolated'/>
      <model type='virtio'/>
      <address type='pci' domain='0x0000' bus='0x02' slot='0x0c' function='0x0'/>
    </interface>
    <serial type='pty'>
      <target port='0'/>
    </serial>
    <console type='pty'>
      <target type='serial' port='0'/>
    </console>
    <channel type='spicevmc'>
      <target type='virtio' name='com.redhat.spice.0'/>
      <address type='virtio-serial' controller='0' bus='0' port='1'/>
    </channel>
    <input type='tablet' bus='usb'/>
    <input type='mouse' bus='ps2'/>
    <input type='keyboard' bus='ps2'/>
    <graphics type='spice' autoport='yes'/>
    <sound model='ich6'>
      <address type='pci' domain='0x0000' bus='0x02' slot='0x02' function='0x0'/>
    </sound>
    <video>
      <model type='qxl' ram='65536' vram='65536' heads='1'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'/>
    </video>
    <hostdev mode='subsystem' type='pci' managed='yes'>
      <source>
        <address domain='0x0000' bus='0x00' slot='0x1b' function='0x0'/>
      </source>
      <address type='pci' domain='0x0000' bus='0x02' slot='0x05' function='0x0'/>
    </hostdev>
    <hostdev mode='subsystem' type='pci' managed='yes'>
      <source>
        <address domain='0x0000' bus='0x00' slot='0x1a' function='0x0'/>
      </source>
      <address type='pci' domain='0x0000' bus='0x02' slot='0x06' function='0x0'/>
    </hostdev>
    <hostdev mode='subsystem' type='pci' managed='yes'>
      <source>
        <address domain='0x0000' bus='0x01' slot='0x00' function='0x0'/>
      </source>
      <rom bar='on' file='/opt/kvm/Hawaii.rom'/>
      <address type='pci' domain='0x0000' bus='0x02' slot='0x07' function='0x0' multifunction='on'/>
    </hostdev>
    <hostdev mode='subsystem' type='pci' managed='yes'>
      <source>
        <address domain='0x0000' bus='0x01' slot='0x00' function='0x1'/>
      </source>
      <address type='pci' domain='0x0000' bus='0x02' slot='0x07' function='0x1'/>
    </hostdev>
    <redirdev bus='usb' type='spicevmc'>
    </redirdev>
    <redirdev bus='usb' type='spicevmc'>
    </redirdev>
    <redirdev bus='usb' type='spicevmc'>
    </redirdev>
    <redirdev bus='usb' type='spicevmc'>
    </redirdev>
    <watchdog model='i6300esb' action='reset'>
      <address type='pci' domain='0x0000' bus='0x02' slot='0x0a' function='0x0'/>
    </watchdog>
    <memballoon model='virtio'>
      <address type='pci' domain='0x0000' bus='0x02' slot='0x09' function='0x0'/>
    </memballoon>
  </devices>
</domain>



----------------------------------------------------------------
Original, working VM:
<domain type='kvm'>
  <name>win8</name>
  <uuid>f58dabd5-975a-4df0-9c13-dcb9b1a44de8</uuid>
  <memory unit='KiB'>8388608</memory>
  <currentMemory unit='KiB'>8388608</currentMemory>
  <vcpu placement='static'>4</vcpu>
  <os>
    <type arch='x86_64' machine='pc-i440fx-2.0'>hvm</type>
  </os>
  <features>
    <acpi/>
    <apic/>
    <pae/>
  </features>
  <cpu mode='custom' match='exact'>
    <model fallback='allow'>Haswell</model>
    <vendor>Intel</vendor>
    <feature policy='require' name='tm2'/>
    <feature policy='require' name='est'/>
    <feature policy='require' name='vmx'/>
    <feature policy='require' name='osxsave'/>
    <feature policy='require' name='smx'/>
    <feature policy='require' name='ss'/>
    <feature policy='require' name='ds'/>
    <feature policy='require' name='vme'/>
    <feature policy='require' name='dtes64'/>
    <feature policy='require' name='abm'/>
    <feature policy='require' name='ht'/>
    <feature policy='require' name='acpi'/>
    <feature policy='require' name='pbe'/>
    <feature policy='require' name='tm'/>
    <feature policy='require' name='pdcm'/>
    <feature policy='require' name='pdpe1gb'/>
    <feature policy='require' name='ds_cpl'/>
    <feature policy='require' name='rdrand'/>
    <feature policy='require' name='f16c'/>
    <feature policy='require' name='xtpr'/>
    <feature policy='require' name='monitor'/>
  </cpu>
  <clock offset='localtime'>
    <timer name='rtc' tickpolicy='catchup'/>
    <timer name='pit' tickpolicy='delay'/>
    <timer name='hpet' present='no'/>
  </clock>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>restart</on_crash>
  <pm>
    <suspend-to-mem enabled='no'/>
    <suspend-to-disk enabled='no'/>
  </pm>
  <devices>
    <emulator>/usr/bin/qemu-kvm</emulator>
    <disk type='block' device='cdrom'>
      <driver name='qemu' type='raw'/>
      <target dev='hdb' bus='ide'/>
      <readonly/>
      <address type='drive' controller='0' bus='0' target='0' unit='1'/>
    </disk>
    <disk type='block' device='disk'>
      <driver name='qemu' type='raw' cache='none' io='native'/>
      <source dev='/dev/sdb'/>
      <target dev='vda' bus='virtio'/>
      <boot order='1'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/>
    </disk>
    <controller type='usb' index='0' model='ich9-ehci1'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x7'/>
    </controller>
    <controller type='usb' index='0' model='ich9-uhci1'>
      <master startport='0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0' multifunction='on'/>
    </controller>
    <controller type='usb' index='0' model='ich9-uhci2'>
      <master startport='2'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x1'/>
    </controller>
    <controller type='usb' index='0' model='ich9-uhci3'>
      <master startport='4'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x2'/>
    </controller>
    <controller type='pci' index='0' model='pci-root'/>
    <controller type='ide' index='0'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>
    </controller>
    <controller type='virtio-serial' index='0'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
    </controller>
    <interface type='bridge'>
      <mac address='52:54:00:1d:c7:48'/>
      <source bridge='bridge0'/>
      <model type='virtio'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
    </interface>
    <interface type='network'>
      <mac address='52:54:00:54:2a:c6'/>
      <source network='Isolated'/>
      <model type='virtio'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x0d' function='0x0'/>
    </interface>
    <serial type='pty'>
      <target port='0'/>
    </serial>
    <console type='pty'>
      <target type='serial' port='0'/>
    </console>
    <channel type='spicevmc'>
      <target type='virtio' name='com.redhat.spice.0'/>
      <address type='virtio-serial' controller='0' bus='0' port='1'/>
    </channel>
    <input type='tablet' bus='usb'/>
    <input type='mouse' bus='ps2'/>
    <input type='keyboard' bus='ps2'/>
    <graphics type='spice' autoport='yes'/>
    <sound model='ich6'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
    </sound>
    <video>
      <model type='qxl' ram='65536' vram='65536' heads='1'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
    </video>
    <hostdev mode='subsystem' type='pci' managed='yes'>
      <source>
        <address domain='0x0000' bus='0x00' slot='0x1a' function='0x0'/>
      </source>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x08' function='0x0'/>
    </hostdev>
    <hostdev mode='subsystem' type='pci' managed='yes'>
      <source>
        <address domain='0x0000' bus='0x00' slot='0x1b' function='0x0'/>
      </source>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x09' function='0x0'/>
    </hostdev>
    <hostdev mode='subsystem' type='pci' managed='yes'>
      <source>
        <address domain='0x0000' bus='0x01' slot='0x00' function='0x0'/>
      </source>
      <rom bar='on' file='/opt/kvm/Hawaii.rom'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x0a' function='0x0'/>
    </hostdev>
    <hostdev mode='subsystem' type='pci' managed='yes'>
      <source>
        <address domain='0x0000' bus='0x01' slot='0x00' function='0x1'/>
      </source>
      <rom bar='on' file='/opt/kvm/Hawaii.rom'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x0b' function='0x0'/>
    </hostdev>
    <redirdev bus='usb' type='spicevmc'>
    </redirdev>
    <redirdev bus='usb' type='spicevmc'>
    </redirdev>
    <redirdev bus='usb' type='spicevmc'>
    </redirdev>
    <redirdev bus='usb' type='spicevmc'>
    </redirdev>
    <memballoon model='virtio'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x0c' function='0x0'/>
    </memballoon>
  </devices>
</domain>

Version-Release number of selected component:
qemu-system-x86-2.0.0-0.2.rc0.fc21

Additional info:
reporter:       libreport-2.2.1
backtrace_rating: 4
cmdline:        /usr/bin/qemu-system-x86_64 -machine accel=kvm -name Win8Q35 -S -machine pc-q35-2.0,accel=kvm,usb=off -cpu Haswell,+abm,+pdpe1gb,+rdrand,+f16c,+osxsave,+pdcm,+xtpr,+tm2,+est,+smx,+vmx,+ds_cpl,+monitor,+dtes64,+pbe,+tm,+ht,+ss,+acpi,+ds,+vme -m 8192 -realtime mlock=off -smp 1,maxcpus=4,sockets=1,cores=2,threads=2 -uuid 2d5506dc-5fa8-4857-a457-a82eb647243d -no-user-config -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/Win8Q35.monitor,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=localtime,driftfix=slew -global kvm-pit.lost_tick_policy=discard -no-hpet -no-shutdown -boot order=c,menu=on,strict=on -device i82801b11-bridge,id=pci.1,bus=pcie.0,addr=0x1e -device pci-bridge,chassis_nr=2,id=pci.2,bus=pci.1,addr=0x1 -device ich9-usb-ehci1,id=usb,bus=pci.2,addr=0x3.0x7 -device ich9-usb-uhci1,masterbus=usb.0,firstport=0,bus=pci.2,multifunction=on,addr=0x3 -device ich9-usb-uhci2,masterbus=usb.0,firstport=2,bus=pci.2,addr=0x3.0x1 -device ich9-usb-uhci3,masterbus=usb.0,firstport=4,bus=pci.2,addr=0x3.0x2 -device virtio-serial-pci,id=virtio-serial0,bus=pci.2,addr=0x4 -drive file=/dev/sdb,if=none,id=drive-virtio-disk0,format=raw,cache=none,aio=native -device virtio-blk-pci,scsi=off,bus=pci.2,addr=0xb,drive=drive-virtio-disk0,id=virtio-disk0 -drive 'file=/Storage/Data/My Softwares/SO Images/Windows/Windows81PRO.iso,if=none,id=drive-ide0-0-0,readonly=on,format=raw' -device ide-cd,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0 -netdev tap,fd=25,id=hostnet0,vhost=on,vhostfd=26 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:1d:c7:48,bus=pci.2,addr=0x1 -netdev tap,fd=27,id=hostnet1,vhost=on,vhostfd=28 -device virtio-net-pci,netdev=hostnet1,id=net1,mac=52:54:00:54:2a:c6,bus=pci.2,addr=0xc -chardev pty,id=charserial0 -device isa-serial,chardev=charserial0,id=serial0 -chardev spicevmc,id=charchannel0,name=vdagent -device virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=com.redhat.spice.0 -device usb-tablet,id=input0 -spice port=5900,addr=127.0.0.1,disable-ticketing,seamless-migration=on -device qxl-vga,id=video0,ram_size=67108864,vram_size=67108864,bus=pcie.0,addr=0x1 -device intel-hda,id=sound0,bus=pci.2,addr=0x2 -device hda-duplex,id=sound0-codec0,bus=sound0.0,cad=0 -device i6300esb,id=watchdog0,bus=pci.2,addr=0xa -watchdog-action reset -chardev spicevmc,id=charredir0,name=usbredir -device usb-redir,chardev=charredir0,id=redir0 -chardev spicevmc,id=charredir1,name=usbredir -device usb-redir,chardev=charredir1,id=redir1 -chardev spicevmc,id=charredir2,name=usbredir -device usb-redir,chardev=charredir2,id=redir2 -chardev spicevmc,id=charredir3,name=usbredir -device usb-redir,chardev=charredir3,id=redir3 -device vfio-pci,host=00:1b.0,id=hostdev0,bus=pci.2,addr=0x5 -device vfio-pci,host=00:1a.0,id=hostdev1,bus=pci.2,addr=0x6 -device vfio-pci,host=01:00.0,id=hostdev2,bus=pci.2,multifunction=on,addr=0x7,rombar=1,romfile=/opt/kvm/Hawaii.rom -device r=0x9
crash_function: pcibus_reset
executable:     /usr/bin/qemu-system-x86_64
kernel:         3.15.0-0.rc0.git9.1.fc21.x86_64
runlevel:       N 5
type:           CCpp
uid:            107

Truncated backtrace:
Thread no. 1 (8 frames)
 #4 pcibus_reset at hw/pci/pci.c:250
 #5 qbus_reset_one at hw/core/qdev.c:246
 #6 qdev_walk_children at hw/core/qdev.c:400
 #7 qbus_walk_children at hw/core/qdev.c:366
 #8 qemu_devices_reset at vl.c:1860
 #9 qemu_system_reset at vl.c:1873
 #10 main_loop_should_exit at vl.c:2008
 #11 main_loop at vl.c:2048