Code review comment for ~paelzer/ubuntu/+source/libvirt:bug-1828495-arch-capability-eoan

Base string as detected is:

-cpu Cascadelake-Server,ss=on,vmx=on,hypervisor=on,tsc_adjust=on,umip=on,pku=on,md-clear=on,stibp=on,arch-capabilities=on,xsaves=on,invtsc=on

And with a silly but effective test:
  <qemu:commandline>
    <qemu:arg value='-cpu'/>
    <qemu:arg value='Cascadelake-Server,ss=on,vmx=on,hypervisor=on,tsc_adjust=on,umip=on,pku=on,md-clear=on,stibp=on,arch-capabilities=on,xsaves=on,invtsc=on,rdctl-no=on,ibrs-all=on,skip-l1dfl-vmentry=on,mds-no=on'/>
  </qemu:commandline>

That made the guest start with these features.
Which implies qemu can pass/use them right?

With these I get:
ubuntu@eoan:~$ sudo rdmsr 0x10a
2b

Uploading this and filing a bug for the fixup of the domcaps between now and Eoan release