kvm增加UEFI支持

参考：http://ju.outofmemory.cn/entry/226516

wget http://www.kraxel.org/repos/firmware.repo -O /etc/yum.repos.d/firmware.repo

yum install edk2.git-ovmf-x64

vi /etc/libvirt/qemu.conf, and add this section at the top of the file:

nvram = [
    "/usr/share/edk2.git/ovmf-x64/OVMF_CODE-pure-efi.fd:/usr/share/edk2.git/ovmf-x64/OVMF_VARS-pure-efi.fd",
 ]

重启libvirtd

systemctl restart libvirtd