Ways we harden our KVM hypervisor at Google Cloud: Security in plaintext
&gt; Non-QEMU implementation: Google does not use QEMU, the user-space virtual machine monitor and hardware emulation. Instead, we wrote our own user-space virtual machine monitor that has the following security advantages over QEMU: Simple host and guest architecture support matrix. QEMU supports a large matrix of host and guest architectures, along with different modes and devices that significantly increase complexity.<p>I&#x27;ve noticed that a lot of projects that <i>do</i> support multiple architectures, particularly obscure ones, tend to find oddball edge cases more easily than those that don&#x27;t. For example, not assuming the endianness of the CPU arch forces you to get network code to cooperate well.<p>&gt; Because we support a single architecture and a relatively small number of devices, our emulator is much simpler.<p>No doubt it&#x27;s simpler than QEMU but I wonder if adding tests to QEMU, even if they&#x27;re only for the specific architectures they&#x27;re running (most likely x86-64) would have been just as usable.<p>Then again when you&#x27;re Google and have the resources to build a VM runtime from the ground up it&#x27;s easier to convince management that &quot;<i>This is the right decision!</i>&quot;.