Add support for `cpu-config`

[ico-nox]

Hello,

I'm using firecracker and i want to use flintlock more, but i'm stuck with an old CPU that doesn't support XSAVE/AVX (Capabilities 56 on KVM).

When i start a microvm i have to add this to the firecracker.cfg :

{
<...>
  "cpu-config": {
    "kvm_capabilities": ["!56"] 
  },
<...>
}

if i don't, i get a KVM error. Firecracker added a flag to remove specific capabilities but i can't use flintlock because i need to add it manually to the firecracker.cfg each time.

Could you add a command flag to set it directly in the config via Flintlock ?

Thanks !

[richardcase]

We'll also need to add it Flintlock, i'll transfer this issue.