Created attachment 585138 [details]
libvirtd crash log

Description of problem:
libvirtd will crash when tight loop of hotplug/unplug PCI device to guest without managed=yes

Version-Release number of selected component (if applicable):
qemu-kvm-rhev-0.12.1.2-2.292.el6.x86_64
libvirt-0.9.10-20.el6.x86_64
kernel-2.6.32-272.el6.x86_64

How reproducible:
100%

Steps to Reproduce:
Setup

1. Enable VT-d on your host                                              
2. edit the /boot/grub/grub.conf like this
Add the kernel option 'intel_iommu=on'
Reset machine.
3. Run command:
    modprobe -r kvm_intel
    modprobe -r kvm
    modprobe kvm allow_unsafe_assigned_interrupts=1
    modprobe kvm_intel

Actions

1. Start a guest (RHEL6)
2. # lspci |grep Eth
3. Select one PCI device
# lspci -n | grep 02:00.0
4. # virsh nodedev-dettach pci_0000_02_00_0
 Detach both of nic device in the same bus:
   # virsh nodedev-dettach pci_0000_02_00_1
5. # virsh nodedev-reset pci_0000_02_00_0
6. # virsh nodedev-dumpxml pci_0000_02_00_0
7. Edit vtd.xml (according to the bus,slot,function number you got from nodedev-dumpxml command)

   <hostdev mode='subsystem' type='pci'>
            <source>
                <address bus='0x02' slot='0' function='0'/>
            </source>
    </hostdev>

8.run the following script:
   # cat script.sh
   #!/bin/sh
   for ((i=0; i < 300; i++))
   do
   echo $i
   virsh attach-device test vtd.xml
   sleep 5
   virsh detach-device test vtd.xml
   sleep 5
   done
   # sh script.sh

Actual results:
First 1,2 or more times will succeed.
But for 3 or later:
3 
Device attached successfully

error: Failed to detach device from vtd.xml
error: End of file while reading data: Input/output error

4
error: Failed to reconnect to the hypervisor
error: no valid connection
error: Failed to connect socket to '/var/run/libvirt/libvirt-sock': Connection refused

and 
# service libvirtd status
libvirtd dead but pid file exists


Expected results:
loop hotplug/unhotplug successfully and libvirtd is alive

Additional info: