Bug 1167072

Can you provide the exact libvirt version, the XML of the failing VM and the exact error message? (by running virt-manager with --debug in a terminal)

Without that, I can only guess that 'copy from host' is done by virt-manager and it also includes CPU features that don't work with save.

Created attachment 981601 [details]
VM XML as a 'generic' CPU

Created attachment 981602 [details]
VM definition after changing CPU type to match host 'westmere'

Created attachment 981603 [details]
virt-manager --debug output showing errors on 'save' operation

The Westmere XML explicitly lists the 'invtsc' feature which blocks save/migration. Deleting the feature or using <cpu mode='host-model'/> should both produce a CPU that allows save.

Moving the bug to virt-manager to see if it can stop adding this non-migratable feature.

I don't think virt-manager should get to this level of details and filtering out non-migratable features, virt-manager reads this information directly from the cpu_map.xml file (it has been changed upstream and in RHEL-7).  The easiest way to workaround it is to choose a CPU which hasn't that feature (or manually drop it) from the XML.

Great - disabling 'invtsc' explicitly does seem to fix the problem.  I see that RHEL7 doesn't specify it.  It does seem to be a serious portability problem that 'copy from host' results in an un-saveable guest.

that's why virt-manager changed a lot in RHEL-7 and we are late in RHEL-6 to think about back-porting it.  It seems that the best solution is to choose a different model or manually drop "invtsc" as you have done.

*** Bug 1188245 has been marked as a duplicate of this bug. ***

I can reproduce this issue with package:
python-virtinst-0.600.0-24.el6.noarch
virt-manager-0.9.0-28.el6.x86_64

steps to reproduce:
1. Use virt-install cmd install a guest with option "--cpu host":
# virt-install -n cpu-test-old -r 1024 --cpu host --disk=/var/tmp/cpu-test-old.img,size=5 --cdrom=/iso/RHEL-6.6-20140926.0-Server-x86_64-dvd1.iso 

Starting install...
Creating storage file cpu-test-old.img                                                                                                | 5.0 GB     00:00     
Creating domain...        
...

Result: Installation finished with no error.
# virsh dumpxml cpu-test-old
...
  <cpu mode='custom' match='exact'>
    <model fallback='allow'>Nehalem</model>
    <vendor>Intel</vendor>
    <feature policy='require' name='avx'/>
    <feature policy='require' name='tsc-deadline'/>
    <feature policy='require' name='dtes64'/>
    <feature policy='require' name='xsave'/>
    <feature policy='require' name='vmx'/>
    <feature policy='require' name='xtpr'/>
    <feature policy='require' name='pcid'/>
    <feature policy='require' name='est'/>
    <feature policy='require' name='monitor'/>
    <feature policy='require' name='smx'/>
    <feature policy='require' name='tm'/>
    <feature policy='require' name='pclmuldq'/>
    <feature policy='require' name='acpi'/>
    <feature policy='require' name='vme'/>
    <feature policy='require' name='osxsave'/>
    <feature policy='require' name='tm2'/>
    <feature policy='require' name='ht'/>
    <feature policy='require' name='pdcm'/>
    <feature policy='require' name='ds'/>
    <feature policy='require' name='invtsc'/>
    <feature policy='require' name='rdtscp'/>
    <feature policy='require' name='ss'/>
    <feature policy='require' name='pbe'/>
    <feature policy='require' name='ds_cpl'/>
    <feature policy='require' name='x2apic'/>
  </cpu>
...

2. Use virsh cmd to save the guest:
# virsh save cpu-test-old /tmp/cpu-test-old.save
error: Failed to save domain cpu-test-old to /tmp/cpu-test-old.save
error: internal error unable to execute QEMU command 'migrate': An undefined error has ocurred

Then try to verify this bug with new build:
virt-manager-0.9.0-29.el6.x86_64
python-virtinst-0.600.0-26.el6.noarch

steps to verify:
1.
# virt-install -n cpu-test -r 1024 --cpu host --disk=/var/tmp/cpu-test.img,size=5 --cdrom=/iso/RHEL-6.6-20140926.0-Server-x86_64-dvd1.iso 

Starting install...
Creating storage file cpu-test.img                                                                                                    | 5.0 GB     00:00     
Creating domain...                                                                                                                    |    0 B     00:00     
...
Result: Installation finished with no error.

# virsh dumpxml cpu-test 
...
  </features>
  <cpu mode='host-model'>
    <model fallback='allow'/>
  </cpu>
...
2.
# virsh save cpu-test /tmp/cpu-test.save2 

Domain cpu-test saved to /tmp/cpu-test.save2

# virsh restore /tmp/cpu-test.save2 
Domain restored from /tmp/cpu-test.save2

Result: Guest can be saved/restored successfully.
So move this bug from ON_QA to VERIFIED.

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://rhn.redhat.com/errata/RHBA-2015-1372.html