Almost on all CPUs used in Macs Virtualization is supported, but in several Mac models it may be disabled in firmware.
How to check that Intel VT-x is supported in CPU:
Open Terminal application ( Application > Utilities > Terminal)
Copy/paste command bellow:
sysctl -a | grep machdep.cpu.features
You may see output similar to the one bellow:
If you see VMX entry then CPU supports Intel VT-x feature, but it still may be disabled.