i don't think the information that unprivilleged VMs can obtain from that is necessarily reliable. for example with Xen as hypervisor only dom0 is privilleged (as management console for the system) and still it needs to call dedicated tooling in order to read or manage CPU features like clock speed or frequency scaling
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but is it possible to verify that the cloud provider has applied the update?
The SEV-SNP attestation includes the microcode version. https://www.amd.com/content/dam/amd/en/documents/developer/l...
Yes, it is. You do have to have some infrastructure you trust somewhere to validate an attestation report from the confidential VM.
/proc/cpuinfo shows the current microcode version
/proc/cpuinfo shows whatever the hypervisor said, often simply "microcode : 0x1000065"
https://github.com/torvalds/linux/commit/518e7b94817abed94be... https://github.com/qemu/qemu/blob/ac6721b88df944ade0048822b2...
i don't think the information that unprivilleged VMs can obtain from that is necessarily reliable. for example with Xen as hypervisor only dom0 is privilleged (as management console for the system) and still it needs to call dedicated tooling in order to read or manage CPU features like clock speed or frequency scaling