QEMU 6.0 On The Way With LTO Support, AMD SEV-ES Guests, Multi-Process Experiment

Written by Michael Larabel in Virtualization on 25 March 2021 at 04:12 PM EDT. 12 Comments
This week marked the hard feature freeze for QEMU 6.0 along with the tagging of QEMU 6.0-rc0. The QEMU 6.0 release should happen around the end of April for this important piece of the open-source Linux virtualization stack.

QEMU 6.0 is a big feature update and will be seeing weekly release candidates until the stable release is ready to ship around the end of April. Among the changes coming with QEMU 6.0 are:

- QEMU can now be built with link-time optimizations (LTO) and also supports LLVM Control-Flow Integrity (CFI) too.

- Support for running AMD SEV-ES encrypted guests is now (finally) in place.

- New experimental options for supporting out-of-process device emulation. This work-in-progress, experimental feature is for multi-process QEMU. The goal with the multi-process QEMU is to run emulated devices in separate processes to increase overall security rather than having one large monolithic QEMU process. The multi-process QEMU work is led by Oracle engineers but for QEMU 6.0 is still in its early stage with just supporting an LSI SCSI controller emulated device so far adapted.

- Security fixes for QEMU's VirtIO-FS support.

- The QEMU GUI with VNC now supports cursors with alpha channels. The VNC code also now supports extended desktop resize. The VirtIO-VGA mode with QEMU 6.0 in turn should have the guest display adapt to the VNC client window on resize.

- An experimental background RAM snapshot feature.

- A variety of QEMU RISC-V improvements, including initial work for supporting 32-bit CPUs on 64-bit software builds, initial RISC-V system documentation, and various features wired up.

- QEMU now supports emulating the ARMv8.1-M architecture and the Cortex M55 CPU. Various ARMv8 extensions like SEL2, TTST, DIT, and MemTag are now supported too for emulation.

- Support for QEMU to emulate Qualcomm Hexagon DSP units.

- Loongson-3 virt machine added.

- The new and more powerful m68k machine.

The exhaustive list of big and small changes for QEMU 6.0 can be found via the QEMU Wiki. The QEMU 6.0-rc0 release can be downloaded from QEMU.org.
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