Created attachment 427556 [details]
rhel-5.5-64-hvm.conf

Description of problem:
Vbd device of HVM guest lost after local migration, and the following reboot
will fail due to no bootable device found. Remote migration do not have this issue.

Version-Release number of selected component (if applicable):
xen-3.0.3-113.el5
kernel-xen-2.6.18-203.el5
kernel-xen-devel-2.6.18-203.el5

How reproducible:
Always

Steps to Reproduce:
1.xm create rhel-5.5-64-hvm.conf(config file as attachment)
2.check vbd device:
  xm list -l rhel-5.5-64-hvm
  please notice the device/vbd segment,like:
    (device
        (vbd
            (backend 0)
            (dev hda:disk)
            (uname
                file:/data/xen-autotest/client/tests/xen/images/RHEL-Server-5.5-64-hvm.raw
            )
            (mode w)
        )
    )
3.local migration:
  xm migrate -l rhel-5.5-64-hvm localhost
4.check vbd device:
  xm list -l rhel-5.5-64-hvm
  this time, please notice that there's no device/vbd segment like listed in step2, it was lost.
5.reboot the hvm guest

ERROR messages from xend.log:
[...]
[2010-06-29 11:21:53 xend.XendDomainInfo 3435] DEBUG (XendDomainInfo:947) XendDomainInfo.completeRestore done
[2010-06-29 11:21:53 xend 3435] DEBUG (DevController:160) Waiting for devices vif.
[2010-06-29 11:21:53 xend 3435] DEBUG (DevController:166) Waiting for 0.
[2010-06-29 11:21:53 xend.XendDomainInfo 3435] DEBUG (XendDomainInfo:1257) XendDomainInfo.handleShutdownWatch
[2010-06-29 11:21:53 xend 3435] DEBUG (DevController:538) hotplugStatusCallback /local/domain/0/backend/vif/2/0/hotplug-status.
[2010-06-29 11:21:53 xend 3435] DEBUG (DevController:552) hotplugStatusCallback 1.
[2010-06-29 11:21:53 xend 3435] DEBUG (DevController:160) Waiting for devices usb.
[2010-06-29 11:21:53 xend 3435] DEBUG (DevController:160) Waiting for devices vbd.
[2010-06-29 11:21:53 xend 3435] DEBUG (DevController:166) Waiting for 768.
[2010-06-29 11:21:53 xend 3435] DEBUG (DevController:538) hotplugStatusCallback /local/domain/0/backend/vbd/2/768/hotplug-status.
[2010-06-29 11:21:53 xend 3435] DEBUG (DevController:552) hotplugStatusCallback 5.
[2010-06-29 11:21:53 xend 3435] ERROR (XendCheckpoint:295) Device 768 (vbd) could not be connected.
File /var/run/xen-autotest/images/RHEL-Server-5.5-64-hvm.raw is loopback-mounted through /dev/loop0,
which is mounted in a guest domain,
and so cannot be mounted now.
Traceback (most recent call last):
  File "/usr/lib64/python2.4/site-packages/xen/xend/XendCheckpoint.py", line 293, in restore
    dominfo.waitForDevices() # Wait for backends to set up
  File "/usr/lib64/python2.4/site-packages/xen/xend/XendDomainInfo.py", line 2421, in waitForDevices
    self.waitForDevices_(c)
  File "/usr/lib64/python2.4/site-packages/xen/xend/XendDomainInfo.py", line 1440, in waitForDevices_
    return self.getDeviceController(deviceClass).waitForDevices()
  File "/usr/lib64/python2.4/site-packages/xen/xend/server/DevController.py", line 162, in waitForDevices
    return map(self.waitForDevice, self.deviceIDs())
  File "/usr/lib64/python2.4/site-packages/xen/xend/server/DevController.py", line 196, in waitForDevice
    raise VmError("Device %s (%s) could not be connected.\n%s" %
VmError: Device 768 (vbd) could not be connected.
File /var/run/xen-autotest/images/RHEL-Server-5.5-64-hvm.raw is loopback-mounted through /dev/loop0,
which is mounted in a guest domain,
and so cannot be mounted now.
[...]
 
Actual results:
Reboot failed with error(also could see attachment):
Booting from Hard Disk...
Boot from Hard Disk failed: could not read the boot disk
FATAL: No bootable device.

Expected results:
No vbd device lost and Hvm guest should reboot successfully.

Additional info:
Tried with remote migration, do not have this issue.