Checks if the address is in a shadowed region, and sends the request to pio to be serviced by the device backing up that range. Based on: https://gem5-review.googlesource.com/c/amd/gem5/+/23484 Change-Id: I4d5b46cccd6203523008b2e9545d55eb62130964 Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/46159 Reviewed-by: Matt Sinclair <mattdsinclair@gmail.com> Reviewed-by: Jason Lowe-Power <power.jg@gmail.com> Maintainer: Matt Sinclair <mattdsinclair@gmail.com> Tested-by: kokoro <noreply+kokoro@google.com>