dev, kvm: Add a fast KVM-aware mode in DmaReadFifo

Use a fast, functional, read operations keep the DMA FIFO full when
running in KVM mode.

Change-Id: I5b378c2fb6a1d3e687cef15e807e63a0a53a60e2
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/2226
Reviewed-by: Rahul Thakur <rjthakur@google.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
2 files changed