arch: cpu: Rename *FloatRegBits* to *FloatReg*.

Now that there's no plain FloatReg, there's no reason to distinguish
FloatRegBits with a special suffix since it's the only way to read or
write FP registers.

Change-Id: I3a60168c1d4302aed55223ea8e37b421f21efded
Reviewed-on: https://gem5-review.googlesource.com/c/14460
Reviewed-by: Brandon Potter <Brandon.Potter@amd.com>
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Gabe Black <gabeblack@google.com>

arm: Stop using the FloatReg and FloatRegBits types.

This will let us make those types 64 bits to be in line with the other
architectures.

Change-Id: I5aef5199f4d2d5bb1558afedac5c6c92bf95c021
Reviewed-on: https://gem5-review.googlesource.com/c/13621
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>

kvm, arm: Switch to the device EQ when accessing ISA devices

ISA devices typically run in the device event queue. Previously, we
assumed that devices would perform their own EQ migrations as
needed. This isn't ideal since it means we have different conventions
for IO devices and ISA devices. Switch to doing migrations in the KVM
CPU instead to make the behavior consistent.

Change-Id: I33b74480fb2126b0786dbdbfdcfa86083384250c
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/4288
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>

arm,kvm: update CP15 timer model when exiting Kvm

The ARM MiscRegs implementation has two interfaces: 'normal'
and 'no effect'. The latter acts as a way to access the
backing store without architectural 'effects'. For instance,
a normal write to a timer compare value would call into the
timer model to emulate the device. The 'no effect' interface,
however, would just write the value into the register backing
store and do nothing else.

For Kvm execution, a delicate balance must be struck for the
timer device specifically. We need the code in the model
to be run, because it contains state other than the register
backing store that must stay in sync. On the other hand, we
don't necessarily want the timer model to schedule gem5
events when this happens.

In this commit, we ensure that we use the 'effectful'
MiscReg interface when copying the CP15 timer registers
from Kvm back into gem5. The prior commit makes sure
that this doesn't generate unnecessary timer events
or interrupts.

Change-Id: Id414c2965bd07fc21ac95e3d581ccc9f55cef9f9
Reviewed-on: https://gem5-review.googlesource.com/3543
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

kvm, arm: Fix incorrect PSTATE sync

The state transfer code wasn't reading back PSTATE correctly from the
CPU prior to updating the thread context and was incorreclty writing
the register as a 32-bit value when updating KVM. Correctly read back
the state before updating gem5's view of PSTATE and cast the value to
a uint64_t.

Change-Id: I0a6ff5b77b897c756b20a20f65c420f42386360f
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/2963
Reviewed-by: Rahul Thakur <rjthakur@google.com>

arm, kvm: Override the kernel's default MPIDR value

The kernel and gem5 derive MPIDR values from CPU IDs in slightly
different ways. This means that guests running in a multi-CPU setup
sometimes fail to bring up secondary CPUs. Fix this by overriding the
MPIDR value in virtual CPUs just after they have been instantiated.

Change-Id: I916d44978a9c855ab89c80a083af45b0cea6edac
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Curtis Dunham <curtis.dunham@arm.com>
Reviewed-by: Sascha Bischoff <sascha.bischoff@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/2461
Reviewed-by: Weiping Liao <weipingliao@google.com>

arm, kvm: enable running 32-bit Guest under ARM KVM64

1) Pass KVM_ARM_VCPU_EL1_32BIT to kvmArmVCpuInit
when running 32-bit OS

2) Correctly map 64-bit registers to banked 32-bit ones

Change-Id: I1dec6427d6f5c3bba599ccdd804f1dfe80d3e670
Reviewed-on: https://gem5-review.googlesource.com/2261
Maintainer: Rahul Thakur <rjthakur@google.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>

arm, kvm: fix saving/restoring conditional flags in ARM KVM64

The gem5 stores flags separately from other fields CPSR, so we need to
split them out and recombine on trips to/from KVM.

Change-Id: I28ed00eb6f0e2a1436adfbc51b6ccf056958afeb
Reviewed-on: https://gem5-review.googlesource.com/2260
Reviewed-by: Rahul Thakur <rjthakur@google.com>
Maintainer: Rahul Thakur <rjthakur@google.com>

kvm, arm: Fix compilation errors due to API changes

The checkpoint changes, along with the SMT patches have changed a
number of APIs. Adapt the ArmKvmCPU accordingly.

kvm, arm: Add support for aarch64

This changeset adds support for aarch64 in kvm. The CPU module
supports both checkpointing and online CPU model switching as long as
no devices are simulated by the host kernel. It currently has the
following limitations:

* The system register based generic timer can only be simulated by
the host kernel. Workaround: Use a memory mapped timer instead to
simulate the timer in gem5.

* Simulating devices (e.g., the generic timer) in the host kernel
requires that the host kernel also simulates the GIC.

* ID registers in the host and in gem5 must match for switching
between simulated CPUs and KVM. This is particularly important
for ID registers describing memory system capabilities (e.g.,
ASID size, physical address size).

* Switching between a virtualized CPU and a simulated CPU is
currently not supported if in-kernel device emulation is
used. This could be worked around by adding support for switching
to the gem5 (e.g., the KvmGic) side of the device models. A
simpler workaround is to avoid in-kernel device models
altogether.