Preface: AMD SoCs can have KVM virtualization for embedded multicore systems, especially with ARM-based architectures, as KVM supports various architectures including ARM and has been adapted for embedded platforms. While KVM was initially designed for Intel and AMD x86 processors, its flexibility and portability allowed for ports to the ARM architecture, making it suitable for embedded multicore SoCs.
Ref: The AMD Zen5 branch predictor is a major update for the Zen family, featuring a new “two-ahead” design that allows it to predict up to two branches per clock cycle, a significant increase from the previous “one-ahead” limit.
Background: Any modern 64-bit AMD processor with AMD-V (SVM) virtualization support can utilize KVM-QEMU for virtualization, as KVM is integrated into the Linux kernel and requires only these hardware extensions for acceleration. To use KVM, you need to ensure AMD-V is enabled in your system’s firmware (BIOS/UEFI) and that your Linux distribution’s kernel and QEMU packages are installed and configured.
The branch predictor is a hardware component located within the processor that stores prediction data internally to improve performance by guessing the outcome of conditional branches.
It uses Branch History Buffers (BHT) and Branch Target Buffers (BTB) to keep track of past branch outcomes and the addresses of the branch targets, respectively, which are small, fast on-chip structures, not part of the main memory system.
Vulnerability details: Researchers from ETH Zurich discovered that incomplete isolation of the branch predictor state in AMD CPUs (Zen 1–5) allows a malicious guest VM to influence indirect branch prediction in the host, specifically in user-space components like QEMU.
The attack, named VMSCAPE, enables a guest VM to leak memory from the host QEMU process at a rate of 32 bytes/sec, including sensitive data like disk encryption keys.
Official announcement: For details, please refer to the link – https://www.amd.com/en/resources/product-security/bulletin/amd-sb-7046.html
