These patches add support for cpuid functions that take a 'count' parameter
in addition to the function number. With these patches, KVM can run a VM
started with a newer CPU type (coreduo, core2duo). These patches also pave
way for a "host" CPU type, where we could pass the CPU type of the current
host to the VM.
v3 uses the as-yet unused KVM_SET_CPUID2 interface, which was written to
support this functionality. Since we rely on kernel versions 2.6.25 at a
minimum for KVM and the SET_CPUID2 interface was introduced in 2.6.25, we're
safe with this.