uefistored is a service that runs in dom0 userspace for servicing port
IO RPC requests from the OVMF XenVariable module, thus providing a
protected UEFI Variables Service implementation.
uefistored (the executable is simply uefistored) is started by the XAPI
stack upon running a VM. One running uefistored process exists per HVM
domain start via XAPI.
uefistored uses Xen's libxen to register itself as a device emulator
for the HVM domU that XAPI has started. XenVariable, found in OVMF,
knows how to communicate with uefistored using the device emulation
protocol.
