Memory sharing device

Hi,

for our purposes we need to access host's memory (e.g. Vulkan buffers,
but we also considering other things, like running all drivers in
userspace) directly from a linux guest (Android). I implemented a
device in QEMU and a linux driver for it:

https://android.googlesource.com/kernel/goldfish/+/android-goldfish-4.14-dev/drivers/misc/goldfish_address_space.c

https://android.googlesource.com/platform/external/qemu/+/emu-master-dev/hw/pci/goldfish_address_space.c

during upstreaming the driver it was suggested that developing a
virtio spec could be a better approach than inventing our specific
driver and device.

Could you please advise how to start?

Thank you.

Regards,
Roman.