Port qemu-kvm's KVM MCE (Machine Check Exception) handling to qemu. It allows qemu to propagate MCEs to the guest.
v2: - rename do_qemu_ram_addr_from_host. - fix kvm_on_sigbus/kvm_on_sigbus_vcpu naming. - fix bank register restoration (Dean Nelson). v3: - condition MCE generation on MCE_SEG_P bit (Huang Ying).