Open Source Summit + Embedded Linux Conference Europe 2020

Some security features (e.g. write-protect kernel code, SMEP) are deployed in kernel to raise the bar of vulnerability exploitation. In practice, attackers would defeat or turn off these security features first. A typical way is by breaking code/data integrity of security features through editing page tables. In this case, enforcing linear translation is important to prevent security features being bypassed. But existing approaches to enforce guest linear translation generally lead to much overhead as guest page table changes and CR3 loading must be trapped by VMM. With HLAT enabled, VMM don’t need to monitor guest CR3 page table changes, thus reduces most overhead and improve efficiency. This presentation will first introduce the hardware extensions in HLAT, and then discuss how to build an efficient solution in KVM to enforce guest linear translation.