s390x: empty function stubs in preparation for __KVM_HAVE_GUEST_DEBUG

This patch creates empty function stubs (used by the gdbserver) in preparation
for the hw debugging support by kvm on s390, which will enable the
__KVM_HAVE_GUEST_DEBUG define in the linux headers and require these methods on
the qemu side.

Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Jens Freimann <jfrei@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
(cherry picked from commit 8c01244)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

target-s390x/kvm.c

@@ -362,6 +362,26 @@ int kvm_arch_remove_sw_breakpoint(CPUState *cs, struct kvm_sw_breakpoint *bp)
     return 0;
 }
 
+int kvm_arch_insert_hw_breakpoint(target_ulong addr,
+                                  target_ulong len, int type)
+{
+    return -ENOSYS;
+}
+
+int kvm_arch_remove_hw_breakpoint(target_ulong addr,
+                                  target_ulong len, int type)
+{
+    return -ENOSYS;
+}
+
+void kvm_arch_remove_all_hw_breakpoints(void)
+{
+}
+
+void kvm_arch_update_guest_debug(CPUState *cpu, struct kvm_guest_debug *dbg)
+{
+}
+
 void kvm_arch_pre_run(CPUState *cpu, struct kvm_run *run)
 {
 }
@@ -812,6 +832,11 @@ static int handle_tsch(S390CPU *cpu)
     return ret;
 }
 
+static int kvm_arch_handle_debug_exit(S390CPU *cpu)
+{
+    return -ENOSYS;
+}
+
 int kvm_arch_handle_exit(CPUState *cs, struct kvm_run *run)
 {
     S390CPU *cpu = S390_CPU(cs);
@@ -827,6 +852,9 @@ int kvm_arch_handle_exit(CPUState *cs, struct kvm_run *run)
         case KVM_EXIT_S390_TSCH:
             ret = handle_tsch(cpu);
             break;
+        case KVM_EXIT_DEBUG:
+            ret = kvm_arch_handle_debug_exit(cpu);
+            break;
         default:
             fprintf(stderr, "Unknown KVM exit: %d\n", run->exit_reason);
             break;