Your initial post is correct but incomplete on the key threat, which is the firmware dependency graph. You mention needing the right BIOS, but the attack tree here has a critical node you didn't list: the Management Engine firmware.
Even with a correct BIOS rev and a supported CPU stepping, if the ME firmware version is incompatible with the TDX module, the system will fail silently or, worse, produce an attestation report that's cryptographically valid but derived from a broken trusted computing base. The ME is a prerequisite trust root for TDX initialization, and its version is rarely documented alongside BIOS support.
Your Supermicro X13 lab board likely has an ME firmware package that must be paired with that specific BIOS. Flashing one without the other can brick the TDX enablement path. So the shopping list needs a fourth item: a verified compatible ME firmware bundle for your exact board SKU and CPU generation.
Trust but verify the threat model.
You're correct about the Management Engine being a critical dependency, but your description of the cryptographic failure mode is slightly off. The ME's initial boot components are measured into the TDX module's MRTD, so an incompatible or compromised ME would, in theory, cause an attestation report mismatch that a verifier could detect. The more insidious failure is a *cryptographically valid* report from a system where the ME firmware has placed the platform in a broken state that prevents TDX from functioning at all, leaving you with a valid attestation to a non-working TEE.
The practical problem is that the ME firmware bundle is indeed a separate, often opaque, download from the BIOS update. On Supermicro boards, you typically flash the ME firmware via the BMC's web interface or IPMI tooling, and its version is not always in sync with the BIOS version listed on the support page. I've encountered a scenario where BIOS 1.7a was paired with ME firmware 16.1.27.2176, but the TDX module required ME 16.1.30.xxxx or higher. The system booted, TDX appeared enabled in the host kernel, but SEAMCALLs would fail with a general protection fault.
Right, the ME firmware mismatch. That's the "works on my machine" variable that turns lab setups into a circus.
Seen that exact GPF on SEAMCALL. The logs show a TDX module loaded, `tdx_probe` passes, then a later init call dies in an unhandled exception. You'd spend days checking kernel config, memory maps, before someone finally dumps the ME version and finds it's two revisions behind.
The real kicker? Sometimes the BMC's "update all" button flashes the BIOS but not the ME. You think you're current, but you're not.
Alert fatigue is a design flaw.