VMware Workstation to Transition from Proprietary Code to Open Source KVM

In what may come as a surprise to many, Broadcom's commercial virtual machine software, VMware Workstation, is currently in the process of transitioning from proprietary, closed-source code to the open-source KVM (Kernel-based Virtual Machine) code.

Broadcom's strategy involves moving away from the existing proprietary technological infrastructure to leverage the Linux kernel-based VM technology, KVM, to meet virtualization needs and enhance customer experiences.

The initiative, led by Broadcom engineers, involves submitting multiple kernel patches with the following key points:

• To transition VMware products running on Linux to KVM, certain modifications are necessary to enable KVM to run/resume unmodified VMware virtual machines.
• Initially, enabling the VMware backdoor through an API is allowed (not referring to malicious software). Currently, VMware backdoor configuration is limited to kernel boot parameters, forcing all virtual machines (VMs) on the host to either use or not use the VMware backdoor.
• Introducing a simple cap to enable the VMware backdoor for each VM, with the default setting being kvm.enable_vmware_backdoor boot parameter set to False. This can be changed for each VM through the KVM_CAP_X86_VMWARE_BACKDOOR capability.
• Adding a capability to forward hypercalls to user space. While typically unwelcome, VMware VMs make a significant number of hypercalls from user space, and handling all these calls in the kernel is both impractical and nearly impossible. The changes are minimal, and the maintenance of this code should not pose a significant issue.

It's important to note that these changes apply not only to VMware Workstation Pro for Linux but to all desktop virtualization versions of VMware Workstation, as confirmed by Broadcom to @Phoronix. This will include VMware Workstation Pro for Windows, adopting the widely used KVM open-source technology. This move is expected to save Broadcom costs on continuing to develop and maintain proprietary code and help improve KVM technology with the community's support.

The specific timeline for the release of the new KVM-based VMware Workstation versions remains unclear, with the transition likely not happening until 2025 or later.