Description of problem:
Fail to start a domain which cpu part is generated by "cpu-baseline"

Version-Release number of selected component (if applicable):
qemu-kvm-rhev-2.9.0-1.el7.x86_64

How reproducible:
100%

Steps to Reproduce:

1.prepare 2 hosts both have intel cpu
hostA: # virsh capabilities
<capabilities>
  <host>
    <uuid>4c4c4544-0038-3710-8048-c6c04f353358</uuid>
    <cpu>
      <arch>x86_64</arch>
      <model>Nehalem</model>
      <vendor>Intel</vendor>
      <topology sockets='1' cores='4' threads='2'/>
      <feature name='vme'/>
      <feature name='ds'/>
      <feature name='acpi'/>
      <feature name='ss'/>
      <feature name='ht'/>
      <feature name='tm'/>
      <feature name='pbe'/>
      <feature name='dtes64'/>
      <feature name='monitor'/>
      <feature name='ds_cpl'/>
      <feature name='vmx'/>
      <feature name='est'/>
      <feature name='tm2'/>
      <feature name='xtpr'/>
      <feature name='pdcm'/>
      <feature name='dca'/>
      <feature name='rdtscp'/>
      <feature name='invtsc'/>
      <pages unit='KiB' size='4'/>
      <pages unit='KiB' size='2048'/>
    </cpu>
...
hostB:# virsh capabilities
<capabilities>
  <host>
    <uuid>44454c4c-4d00-1046-8053-b8c04f563258</uuid>
    <cpu>
      <arch>x86_64</arch>
      <model>Penryn</model>
      <vendor>Intel</vendor>
      <topology sockets='1' cores='4' threads='1'/>
      <feature name='vme'/>
      <feature name='ds'/>
      <feature name='acpi'/>
      <feature name='ss'/>
      <feature name='ht'/>
      <feature name='tm'/>
      <feature name='pbe'/>
      <feature name='dtes64'/>
      <feature name='monitor'/>
      <feature name='ds_cpl'/>
      <feature name='vmx'/>
      <feature name='smx'/>
      <feature name='est'/>
      <feature name='tm2'/>
      <feature name='xtpr'/>
      <feature name='pdcm'/>
      <feature name='xsave'/>
      <feature name='osxsave'/>
      <pages unit='KiB' size='4'/>
      <pages unit='KiB' size='2048'/>
    </cpu>
...
2.define a domain on hostB
[root@hostB ~]# virsh list --all
 Id    Name                           State
----------------------------------------------------
 -     V                              shut off

3.generate cpu elements for migration
copy the outputed cpu part of two hosts in step1 to a file "base2hostB.xml", then
#  virsh cpu-baseline base2hostB.xml
<cpu mode='custom' match='exact'>
  <model fallback='allow'>Penryn</model>
  <vendor>Intel</vendor>
  <feature policy='require' name='vme'/>
  <feature policy='require' name='ds'/>
  <feature policy='require' name='acpi'/>
  <feature policy='require' name='ss'/>
  <feature policy='require' name='ht'/>
  <feature policy='require' name='tm'/>
  <feature policy='require' name='pbe'/>
  <feature policy='require' name='dtes64'/>
  <feature policy='require' name='monitor'/>
  <feature policy='require' name='ds_cpl'/>
  <feature policy='require' name='vmx'/>
  <feature policy='require' name='est'/>
  <feature policy='require' name='tm2'/>
  <feature policy='require' name='xtpr'/>
  <feature policy='require' name='pdcm'/>
</cpu>

4. copy the output in step3 to replace the cpu part in domain xml, and try to start the domain
[root@hostB ~]# virsh start V
error: Failed to start domain V
error: the CPU is incompatible with host CPU: Host CPU does not provide required features: ds, acpi, ht, tm, pbe, dtes64, monitor, ds_cpl, vmx, est, tm2, xtpr, pdcm

Actual results:
As in step4, fail to start a domain which cpu part is generated by "cpu-baseline"

Expected results:
Should succeed to start a domain which cpu part is generated by "cpu-baseline"
 
Additional info:
works well with qemu-kvm-rhev-2.8.0-6.el7.x86_64