[nellydpa]

Homomorphic encryption enables computation to be performed on encrypted data without the need to decrypt it on the CPU. Compared to Confidential Computing approaches, the processing complexity of FHE is quite high, especially for tasks that require execution of complicated algorithms, making it hard to scale with this approach. Confidential VMs with AMD SEV decrypt data within VMs and keep it encrypted "in-use" by encrypting memory with a key generated by AMD secure processor (non-extractable) per VM. After processing data and code can be encrypted back to keep it protected at-rest.

[MereInterest]

I don't understand, and couldn't get any information from the article either. If the data are decrypted within the VM, then it is still decrypted at that point, and the host machine can read it.

[theevilsharpie]

The data is transparently encrypted and decrypted specifically within the processor. The OS kernel on the host machine doesn't have access to the unencrypted contents of the guest VM's memory.

> I don't understand, and couldn't get any information from the article either.

See this wiki article for more info on this class of technology: https://en.wikipedia.org/wiki/Data_in_use

[nellydpa]

You can access memory within a VM, not outside of a VM. Host machine with a hypervisor is not within a VM instance, so it will not be able to read your VM memory. The memory is encrypted all the time, but when the instruction has to be executed on CPU, memory controllers (only and only have access to the keys of this VM) decrypt the instruction to execute it on cpu in clear. For FHE, cpu instructions are executed on AES encrypted blocks, and will take significant time, so not very practical today. Does it make sense?