Launch SEV virtual machines inside the bare metal server

I apologize, but there seems to be a misunderstanding in your approach. AWS does not support launching SEV-based guest VMs inside bare metal EC2 servers like m6a by yourself.

AMD SEV-SNP (Secure Encrypted Virtualization - Secure Nested Paging) is a feature that AWS implements at the hypervisor level for specific instance types. It's not designed for customers to set up and manage themselves on bare metal instances.

To use AMD SEV-SNP on EC2:

1. You need to launch a supported instance type directly. These include certain sizes of m6a, c6a, and r6a instance families.

2. You must use the AWS CLI to launch the instance, specifying the "--cpu-options AmdSevSnp=enabled" option.

3. The AMI must have UEFI or UEFI-preferred boot mode and an operating system that supports AMD SEV-SNP (like AL2023, RHEL 9.3, SLES 15 SP4, or Ubuntu 23.04 and later).

4. This must be done in a supported AWS Region (currently only US East (Ohio) and Europe (Ireland)).

You cannot enable AMD SEV-SNP after launching an instance, nor can you set it up yourself on a bare metal instance. The feature is managed by AWS at the infrastructure level to provide the security benefits of memory encryption and attestation.

If you need to use AMD SEV-SNP, I recommend launching a supported instance type with the feature enabled through the AWS CLI, rather than attempting to set it up on a bare metal instance.
Sources
Enable AMD SEV-SNP for an Amazon EC2 instance - Amazon Elastic Compute Cloud
AMD SEV-SNP for Amazon EC2 instances - Amazon Elastic Compute Cloud