You can do that where for instance the VM has PCI and can plug in a virtio RNG device. But a lot of the QEMU setups Guenter Roeck reported issues with are emula

You can do that where for instance the VM has PCI and can plug in a virtio RNG device. But a lot of the QEMU setups Guenter Roeck reported issues with are emulating real (usually old) hardware which didn't have a PCI bus, or any other hardware RNG interface.