Firecracker relies on KVM in the Linux kernel which relies on VT-x or similar. Offering VT-x inside a VM that's already using VT-x is called nested virtualization. EC2 VMs do not support nested virtualization, while others do.

That said, it works fine on EC2 Bare Metal instances.

(n.b., I work on the virtualization stack on Google Compute Engine)

Wouldn’t you want to run firecracker on bare metal anyways. Nested VMs come with a decent perf hit.

Thanks @jsolson for explaining

@bushbaba I wonder how large the percentage hit could be, if it's like 1% or 10%, if you happen to know

And how that percentage hit compares with gvisor performance wise