KVM: PPC: BookE: Allow irq deliveries to inject requests

When injecting an interrupt into guest context, we usually don't need
to check for requests anymore. At least not until today.

With the introduction of EPR, we will have to create a request when the
guest has successfully accepted an external interrupt though.

So we need to prepare the interrupt delivery to abort guest entry
gracefully. Otherwise we'd delay the EPR request.

Signed-off-by: Alexander Graf <agraf@suse.de>
KVM: PPC: BookE: Emulate mfspr on EPR

The EPR register is potentially valid for PR KVM as well, so we need
to emulate accesses to it. It's only defined for reading, so only
handle the mfspr case.

Signed-off-by: Alexander Graf <agraf@suse.de>
KVM: PPC: BookE: Implement EPR exit

The External Proxy Facility in FSL BookE chips allows the interrupt
controller to automatically acknowledge an interrupt as soon as a
core gets its pending external interrupt delivered.

Today, user space implements the interrupt controller, so we need to
check on it during such a cycle.

This patch implements logic for user space to enable EPR exiting,
disable EPR exiting and EPR exiting itself, so that user space can
acknowledge an interrupt when an external interrupt has successfully
been delivered into the guest vcpu.

Signed-off-by: Alexander Graf <agraf@suse.de>
KVM: PPC: BookE: Add EPR ONE_REG sync

We need to be able to read and write the contents of the EPR register
from user space.

This patch implements that logic through the ONE_REG API and declares
its (never implemented) SREGS counterpart as deprecated.

Signed-off-by: Alexander Graf <agraf@suse.de>