Hi,
   I am not running any application inside the HVM. But, after the migration, it always uses 100% cpu.
Xen : 4.0.1
Dom0: Ubuntu 10.04 Server & 2.6.32-bpo.4-xen-amd64
HVM : Ubuntu 10.04 Server 
Xentop Value before the Migration (Sample)
 NAME  STATE   CPU(sec) CPU(%)     MEM(k) MEM(%)  MAXMEM(k) MAXMEM(%) VCPUS 
 Domain-0 -----r       6965      2.7            647168   15.7       no limit         n/a                 1   
 lucid_hvm -----r        567      0.5            2101220   50.9     2101248       50.9                1  
I am using the following command to perform the migration
$xm migrate --live lucid_hvm 192.168.100.11
Xentop Value after the Migration (Sample)
 NAME  STATE   CPU(sec) CPU(%)     MEM(k) MEM(%)  MAXMEM(k) MAXMEM(%) VCPUS 
 Domain-0 -----r       3965      5.7            642163   15.7       no limit         n/a                 1   
 lucid_hvm -----r        569      100.0        2101220   50.9     2101248       50.9               1  
This is how HVM config file looks
   import os, re
   arch = os.uname()[4]
   
   kernel = "/usr/lib/xen/boot/hvmloader"
   
   builder='hvm'
   
   memory = 2048
   maxmem=2048
   shadow_memory = 8
  
  name = "lucid_hvm"
  
  vif = [ 'mac=00:B6:3E:E8:41:2E' ]
  disk = [ 'file:/vmimage/lucid_hvm.img,xvda,w', 'file:/vmimage/ubuntu-10.04.1-server-i386.iso,xvdc:cdrom,r' ]
 
  device_model = '/usr/lib/xen/bin/qemu-dm'
 
  boot="c"
  
  sdl=0
  vnc=1
  vnclisten="0.0.0.0"
  vncconsole=1
  vncpasswd='xyz'
  stdvga=0
  serial='pty'
  usbdevice='tablet'
  
 >
 on_reboot   = 'restart'
 on_crash    = 'restart'
Thanks,
cendhu