This is using SEV-ES (SEV2) which is vulnerable to the severe attack described last year in [1], and unfixable due to the lack of antirollback functionality.

Only SEV-SNP [2] is supposed to address it, but only on new silicon which doesn't exist yet, and that probably not even Google has.

So why is Google releasing this feature if it is so flawed?

[1] https://arxiv.org/pdf/1908.11680.pdf

[2] https://www.amd.com/system/files/TechDocs/SEV-SNP-strengthen...