azure: support Azure TDX CVMs for podvms

[mkulke]

at the moment we only build podvms images for Azure's SNP cvms. I think we need to need to extend the guest-components build-flags to also build the az-vtpm-tdx attester.

it's probably sufficient to extend make KBC="cc_kbc_az_snp_vtpm" to make KBC="cc_kbc_az_snp_vtpm cc_kbc_az_tdx_vtpm" for the guest-components's build. alternatively we can add guest-components build flag cc_kbc_az-cvm-vtpm that covers both.

[cmaf]

@mkulke from the logs in a TDX VM in Azure using the nightly build image, I retrieved

[    0.000000] Hyper-V: Isolation Config: Group A 0x1, Group B 0xbe3

(suggested in https://www.youtube.com/watch?v=bG7T1Stm2c0). Is this sufficient or do we still need additional guest component build flags?

[mkulke]

So, if you are booting an instance size and see this in the logs, you can be positive that we're running on a TDX vm on azure.

sudo dmesg | grep -i encryption
[    0.624581] Memory Encryption Features active: Intel TDX
[    1.029536] software IO TLB: Memory encryption is active and system is using DMA bounce buffers

However if you want to do remote attestation with CoCo we need to add a compile-time-flag (i think) to guest-components: cc_kbc_az_tdx_vtpm, it might automagically work out of the box, but i'd be surprised. you could do a call to api-server-rest from inside the peerpod to see whether you can get a TDX report/TPM quote (kubectl exec into it):

curl http://127.0.0.1:8006/aa/evidence\?runtime_data\=xxxx

[fidencio]

(suggested in https://www.youtube.com/watch?v=bG7T1Stm2c0). Is this sufficient or do we still need additional guest component build flags?

@cmaf, this is sufficient, and this is what we use as part of the cpuid project to check whether the VM is a TDX_GUEST or not, please, see: klauspost/cpuid@3a00e73

You're, indeed, running on a TDX guest!