The c5, m5, t3, c5d, m5d, z1d, r5, r5d, m5a, r5a, a1, c5n, p3dn instance families all use the Nitro Hypervisor, which is based on Linux KVM code but offloading

The c5, m5, t3, c5d, m5d, z1d, r5, r5d, m5a, r5a, a1, c5n, p3dn instance families all use the Nitro Hypervisor, which is based on Linux KVM code but offloading a lot of functionality to the Nitro System instead of using the normative QEMU setup. Firecracker runs as a process in a customer-provided Linux 4.14 or newer kernel using the upstream KVM apis, that can be on an EC2 Metal Instance or on your own hardware.