[PATCH v6 2/4] hw/core/qdev-properties-system: Allow the 'slew' policy only on x86

[Thomas Huth <thuth@redhat.com>]

The 'slew' tick policy is currently enforced to be only available on
x86 via some "#ifdef TARGET_I386" statements in mc146818rtc.c. We
want to get rid of those #ifdefs, so we need a different way of
checking whether the policy is allowed or not. Using the setter
function in hw/core/qdev-properties-system.c seems to be a good
place, so let's add a check here.

Suggested-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 hw/core/qdev-properties-system.c | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/hw/core/qdev-properties-system.c b/hw/core/qdev-properties-system.c
index 54a09fa9ac..d42493f630 100644
--- a/hw/core/qdev-properties-system.c
+++ b/hw/core/qdev-properties-system.c
@@ -33,6 +33,7 @@
 #include "net/net.h"
 #include "hw/pci/pci.h"
 #include "hw/pci/pcie.h"
+#include "hw/i386/x86.h"
 #include "util/block-helpers.h"
 
 static bool check_prop_still_unset(Object *obj, const char *name,
@@ -558,13 +559,38 @@ void qdev_set_nic_properties(DeviceState *dev, NICInfo *nd)
 
 /* --- lost tick policy --- */
 
+static void qdev_propinfo_set_losttickpolicy(Object *obj, Visitor *v,
+                                             const char *name, void *opaque,
+                                             Error **errp)
+{
+    Property *prop = opaque;
+    int *ptr = object_field_prop_ptr(obj, prop);
+    int value;
+
+    if (!visit_type_enum(v, name, &value, prop->info->enum_table, errp)) {
+        return;
+    }
+
+    if (value == LOST_TICK_POLICY_SLEW) {
+        MachineState *ms = MACHINE(qdev_get_machine());
+
+        if (!object_dynamic_cast(OBJECT(ms), TYPE_X86_MACHINE)) {
+            error_setg(errp,
+                       "the 'slew' policy is only available for x86 machines");
+            return;
+        }
+    }
+
+    *ptr = value;
+}
+
 QEMU_BUILD_BUG_ON(sizeof(LostTickPolicy) != sizeof(int));
 
 const PropertyInfo qdev_prop_losttickpolicy = {
     .name  = "LostTickPolicy",
     .enum_table  = &LostTickPolicy_lookup,
     .get   = qdev_propinfo_get_enum,
-    .set   = qdev_propinfo_set_enum,
+    .set   = qdev_propinfo_set_losttickpolicy,
     .set_default_value = qdev_propinfo_set_default_value_enum,
 };
 
-- 
2.31.1