qdev: add "check if address free" callback for buses

Check if an address is free on the bus before plugging in the
device.  This makes it possible to do the check without any
side effects, and to detect the problem early without having
to do it in the realize callback.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20201006123904.610658-5-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/hw/core/qdev.c b/hw/core/qdev.c
index 96772a15bd5b76d3ebe27d45ed1f2c1beb7f5386..74db78df360f046da573c9c92f0c8c4e347e9dd4 100644 (file)
--- a/hw/core/qdev.c
+++ b/hw/core/qdev.c
@@ -94,13 +94,23 @@ static void bus_add_child(BusState *bus, DeviceState *child)
                              0);
 }
 
-void qdev_set_parent_bus(DeviceState *dev, BusState *bus)
+static bool bus_check_address(BusState *bus, DeviceState *child, Error **errp)
+{
+    BusClass *bc = BUS_GET_CLASS(bus);
+    return !bc->check_address || bc->check_address(bus, child, errp);
+}
+
+bool qdev_set_parent_bus(DeviceState *dev, BusState *bus, Error **errp)
 {
     BusState *old_parent_bus = dev->parent_bus;
     DeviceClass *dc = DEVICE_GET_CLASS(dev);
 
     assert(dc->bus_type && object_dynamic_cast(OBJECT(bus), dc->bus_type));
 
+    if (!bus_check_address(bus, dev, errp)) {
+        return false;
+    }
+
     if (old_parent_bus) {
         trace_qdev_update_parent_bus(dev, object_get_typename(OBJECT(dev)),
             old_parent_bus, object_get_typename(OBJECT(old_parent_bus)),
@@ -126,6 +136,7 @@ void qdev_set_parent_bus(DeviceState *dev, BusState *bus)
         object_unref(OBJECT(old_parent_bus));
         object_unref(OBJECT(dev));
     }
+    return true;
 }
 
 DeviceState *qdev_new(const char *name)
@@ -371,7 +382,9 @@ bool qdev_realize(DeviceState *dev, BusState *bus, Error **errp)
     assert(!dev->realized && !dev->parent_bus);
 
     if (bus) {
-        qdev_set_parent_bus(dev, bus);
+        if (!qdev_set_parent_bus(dev, bus, errp)) {
+            return false;
+        }
     } else {
         assert(!DEVICE_GET_CLASS(dev)->bus_type);
     }

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index a160a9da9c6e0f8660a6aa4e032122416d798f6f..277289d56e7645b3ba1037a71881147fab27aae3 100644 (file)
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -3138,7 +3138,7 @@ static bool failover_replug_primary(VirtIONet *n, Error **errp)
         error_setg(errp, "virtio_net: couldn't find primary bus");
         return false;
     }
-    qdev_set_parent_bus(n->primary_dev, n->primary_bus);
+    qdev_set_parent_bus(n->primary_dev, n->primary_bus, &error_abort);
     n->primary_should_be_hidden = false;
     if (!qemu_opt_set_bool(n->primary_device_opts,
                            "partially_hotplugged", true, errp)) {

diff --git a/hw/sd/core.c b/hw/sd/core.c
index 957d116f1a7181448c7ee69a48e19b99d6e32657..08c93b59034d2b0bf20ec34f4d9f6c4142c136b4 100644 (file)
--- a/hw/sd/core.c
+++ b/hw/sd/core.c
@@ -23,6 +23,7 @@
 #include "hw/qdev-core.h"
 #include "hw/sd/sd.h"
 #include "qemu/module.h"
+#include "qapi/error.h"
 #include "trace.h"
 
 static inline const char *sdbus_name(SDBus *sdbus)
@@ -240,7 +241,7 @@ void sdbus_reparent_card(SDBus *from, SDBus *to)
     readonly = sc->get_readonly(card);
 
     sdbus_set_inserted(from, false);
-    qdev_set_parent_bus(DEVICE(card), &to->qbus);
+    qdev_set_parent_bus(DEVICE(card), &to->qbus, &error_abort);
     sdbus_set_inserted(to, true);
     sdbus_set_readonly(to, readonly);
 }

diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
index 72064f4dd4a4f76371e614475940586e89f1c81d..14d476c58759b70c36823f7eeecfeefaca061148 100644 (file)
--- a/include/hw/qdev-core.h
+++ b/include/hw/qdev-core.h
@@ -210,13 +210,24 @@ struct BusClass {
     /* FIXME first arg should be BusState */
     void (*print_dev)(Monitor *mon, DeviceState *dev, int indent);
     char *(*get_dev_path)(DeviceState *dev);
+
     /*
      * This callback is used to create Open Firmware device path in accordance
      * with OF spec http://forthworks.com/standards/of1275.pdf. Individual bus
      * bindings can be found at http://playground.sun.com/1275/bindings/.
      */
     char *(*get_fw_dev_path)(DeviceState *dev);
+
     void (*reset)(BusState *bus);
+
+    /*
+     * Return whether the device can be added to @bus,
+     * based on the address that was set (via device properties)
+     * before realize.  If not, on return @errp contains the
+     * human-readable error message.
+     */
+    bool (*check_address)(BusState *bus, DeviceState *dev, Error **errp);
+
     BusRealize realize;
     BusUnrealize unrealize;
 
@@ -788,7 +799,7 @@ const char *qdev_fw_name(DeviceState *dev);
 Object *qdev_get_machine(void);
 
 /* FIXME: make this a link<> */
-void qdev_set_parent_bus(DeviceState *dev, BusState *bus);
+bool qdev_set_parent_bus(DeviceState *dev, BusState *bus, Error **errp);
 
 extern bool qdev_hotplug;
 extern bool qdev_hot_removed;