KVM: PPC: BookE: Add support for vcpu->mode

Generic KVM code might want to know whether we are inside guest context
or outside. It also wants to be able to push us out of guest context.

Add support to the BookE code for the generic vcpu->mode field that describes
the above states.

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

arch/powerpc/kvm/booke.c

@@ -501,6 +501,15 @@ static int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu)
 			continue;
 		}
 
+		if (vcpu->mode == EXITING_GUEST_MODE) {
+			r = 1;
+			break;
+		}
+
+		/* Going into guest context! Yay! */
+		vcpu->mode = IN_GUEST_MODE;
+		smp_wmb();
+
 		break;
 	}
 
@@ -572,6 +581,8 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 	kvm_guest_exit();
 
 out:
+	vcpu->mode = OUTSIDE_GUEST_MODE;
+	smp_wmb();
 	local_irq_enable();
 	return ret;
 }