Description of problem:
VM failed to save with error "Target CPU feature count 34 does not match source 105"

Version-Release number of selected component (if applicable):
libvirt-10.0.0-6.el9_4.x86_64

How reproducible:
100%

Steps to Reproduce:
1. On a host with cpu model as "Cascadelake-Server-noTSX", prepare a vm with host-model cpu.

# virsh capabilities  | grep "</model>"
      <model>Cascadelake-Server-noTSX</model>
......
# virsh dumpxml rhel --xpath //cpu
<cpu mode="host-model" check="partial"/>

2. Start the VM, and dump the live xml with "--migratable", then save the VM with "--xml" with the xml saved, it will fail:

# virsh start rhel
Domain 'rhel' started

# virsh dumpxml rhel --migratable > rhel_migratable.xml

# virsh save rhel rhel.save --xml rhel_migratable.xml
error: Failed to save domain 'rhel' to rhel.save
error: unsupported configuration: Target CPU feature count 34 does not match source 105

Check the libvirtd log:

2024-03-27 12:41:09.754+0000: 26480: error : virCPUDefIsEqual:1169 : unsupported configuration: Target CPU feature count 34 does not match source 105 

Actual results:
VM failed to save

Expected results:
VM should save successfully

Additional info:
No such issue on libvirt-10.0.0-4.el9_4.x86_64, should be a regression caused by fix in https://issues.redhat.com/browse/RHEL-25995