internal/cloud/gcp/compute: Add SEV_SNP_CAPABLE Guest OS Feature

[travier]

See: coreos/coreos-assembler#3547
See: https://cloud.google.com/blog/products/identity-security/rsa-snp-vm-more-confidential
See: https://issues.redhat.com/browse/COS-2343

---

This pull request includes:

• adequate testing for the new functionality or fixed issue
• adequate documentation informing people about the change such as
  • submit a PR for the guides repository if this PR changed any behavior described there: https://www.osbuild.org/guides/

[thozza]

Hi @travier.

Thanks a lot for the PR. Do you know if all RHEL-9 versions support SNP feature or if it is available only since some specific minor version of RHEL-9?

[thozza]

I rebased the PR using web UI

[travier]

Do you know if all RHEL-9 versions support SNP feature or if it is available only since some specific minor version of RHEL-9?

Unfortunately I don't know. I've asked that to the folks that should know 🙂.

[travier]

From another chat, this is RHEL 9.2 and later only (potentially 9.1 but with lesser support): https://bugzilla.redhat.com/show_bug.cgi?id=2081424

[thozza]

I added a compatibility case for RHEL-9.0, which does not support SEV-SNP and rebased the PR on top of main. The change looks good from my PoV, but I won't approve since I contributed some code in this PR.

[travier]

LGTM

[achilleas-k]

The installer test on RHEL 8.9 has been causing issues all around lately. I did a rebase to help it along.

[ondrejbudai]

No failed test related to this change.