KVM: PPC: Add feature bitmap for magic page

We will soon add SR PV support to the shared page, so we need some
infrastructure that allows the guest to query for features KVM exports.

This patch adds a second return value to the magic mapping that
indicated to the guest which features are available.

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

1 files changed, 4 insertions, 1 deletions

diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 6a53a3f86dae..496d7a5200dc 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -66,6 +66,8 @@ int kvmppc_kvm_pv(struct kvm_vcpu *vcpu)
                 vcpu->arch.magic_page_pa = param1;
                 vcpu->arch.magic_page_ea = param2;
 
+                r2 = 0;
+
                 r = HC_EV_SUCCESS;
                 break;
         }
@@ -76,13 +78,14 @@ int kvmppc_kvm_pv(struct kvm_vcpu *vcpu)
 #endif
 
                 /* Second return value is in r4 */
-                kvmppc_set_gpr(vcpu, 4, r2);
                 break;
         default:
                 r = HC_EV_UNIMPLEMENTED;
                 break;
         }
 
+        kvmppc_set_gpr(vcpu, 4, r2);
+
         return r;
 }