KVM: PPC: Expose magic page support to guest

Now that we have the shared page in place and the MMU code knows about
the magic page, we can expose that capability to the guest!

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index a4cf4b4..fecfe04 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -61,8 +61,19 @@
 	}
 
 	switch (nr) {
+	case HC_VENDOR_KVM | KVM_HC_PPC_MAP_MAGIC_PAGE:
+	{
+		vcpu->arch.magic_page_pa = param1;
+		vcpu->arch.magic_page_ea = param2;
+
+		r = HC_EV_SUCCESS;
+		break;
+	}
 	case HC_VENDOR_KVM | KVM_HC_FEATURES:
 		r = HC_EV_SUCCESS;
+#if defined(CONFIG_PPC_BOOK3S) /* XXX Missing magic page on BookE */
+		r2 |= (1 << KVM_FEATURE_MAGIC_PAGE);
+#endif
 
 		/* Second return value is in r4 */
 		kvmppc_set_gpr(vcpu, 4, r2);