Confidential Computing in the Linux Cloud Stack: A Balancing Act

Public cloud inherently limits the privacy of VMs. Confidential computing protects guest memory, even from hypervisors, addressing privacy concerns. However, supporting confidential VMs requires rethinking the Linux cloud stack, balancing performance and security. This article explores how hardware isolation, software security mechanisms, and confidential computing impact the Linux cloud stack's boot process, secure boot, remote attestation, and more. It analyzes scaling and performance challenges, such as DRAM encryption/decryption, memory page acceptance, and ASID limitations. While confidential computing enhances security, it increases reliance on firmware and hardware, highlighting the security value of open architectures like RISC-V to reduce reliance on third-party trust. The article questions whether the investment in adapting the Linux kernel is worthwhile for the community.