arm,kvm: Fix python imports from global namespace

Change-Id: I31bd3563c2427efd7e520f714b1ca6f480fa4e85
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Ciro Santilli <ciro.santilli@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/20491
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

dev-arm: rename Pl390 to GicV2

The Pl390 model has evolved and acquired a lot of the features from GICv2,
which means that the name is no longer appropriate. Rename it to GICv2
since this is more representative of the supported features.

GICv2 is backwards compatible with the older Pl390, so we decided to
simply rename the class to represent both GICv2 and older interfaces such
as the instead of creating a new separate one.

Change-Id: I1c05fba8b3cb5841c66480e9f05b8c873eba3229
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/12492
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

arm, kvm: remove KvmGic

KvmGic functionality has been subsumed within the new MuxingKvmGic
model, which has Pl390 fallback when not using KVM for fast emulation.
This simplifies configuration and will enable checkpointing between
KVM emulation and full-system simulation.

Change-Id: Ie61251720064c512843015c075e4ac419a4081e8
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>

arm, kvm: implement MuxingKvmGic

This device allows us to, when KVM support is detected and compiled in,
instantiate the same Gic device whether the actual simulation is with
KVM cores or simulated cores. Checkpointing is not yet supported.

Change-Id: I67e4e0b6fb7ab5058e52c933f4f3d8e7ab24981e
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>

sim, kvm: make KvmVM a System parameter

A KVM VM is typically a child of the System object already, but for
solving future issues with configuration graph resolution, the most
logical way to keep track of this object is for it to be an actual
parameter of the System object.

Change-Id: I965ded22203ff8667db9ca02de0042ff1c772220
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>

kvm, arm: Make GIC interrupt lines configurable

Add support for overriding the number of interrupt lines in the ARM
KvmGic.

Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Radhika Jagtap <radhika.jagtap@arm.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>

kvm, arm, dev: Add an in-kernel GIC implementation

This changeset adds a GIC implementation that uses the kernel's
built-in support for simulating the interrupt controller. Since there
is currently no support for state transfer between gem5 and the
kernel, the device model does not support serialization and CPU
switching (which would require switching to a gem5-simulated GIC).