KVM: PPC: Stub emulate CFAR and PURR SPRs

Recent Linux versions use the CFAR and PURR SPRs, but don't really care about
their contents (yet). So for now, we can simply return 0 when the guest wants
to read them.

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

arch/powerpc/kvm/book3s_emulate.c

@@ -473,6 +473,10 @@ int kvmppc_core_emulate_mfspr(struct kvm_vcpu *vcpu, int sprn, int rt)
 	case SPRN_HID5:
 		kvmppc_set_gpr(vcpu, rt, to_book3s(vcpu)->hid[5]);
 		break;
+	case SPRN_CFAR:
+	case SPRN_PURR:
+		kvmppc_set_gpr(vcpu, rt, 0);
+		break;
 	case SPRN_GQR0:
 	case SPRN_GQR1:
 	case SPRN_GQR2: