Also wondering a bit how your HV looks at DMA capable devices. does it restrict DMA apertures based on some policies or so in order to ensure they can only write/read certain places? how is that managed if so? theres multiple angles where TPM/secure boot might not be enough. you can use iommu and things like amd-vi to highly restrict these types of devices and interactions.
other then that super cool project really. Like to see a HV being built on Sel4 its a very nice base to build up from if formal verification is your goal.