Merge remote-tracking branch 'remotes/bonzini-gitlab/tags/for-upstream' into staging

* qtest documentation improvements (Eduardo, myself)
* libqtest event buffering (Maxim)
* use RCU for list of children of a bus (Maxim)
* move more files to softmmu/ (myself)
* meson.build cleanups, qemu-storage-daemon fix (Philippe)

# gpg: Signature made Mon 12 Oct 2020 16:55:19 BST
# gpg:                using RSA key F13338574B662389866C7682BFFBD25F78C7AE83
# gpg:                issuer "pbonzini@redhat.com"
# gpg: Good signature from "Paolo Bonzini <bonzini@gnu.org>" [full]
# gpg:                 aka "Paolo Bonzini <pbonzini@redhat.com>" [full]
# Primary key fingerprint: 46F5 9FBD 57D6 12E7 BFD4  E2F7 7E15 100C CD36 69B1
#      Subkey fingerprint: F133 3857 4B66 2389 866C  7682 BFFB D25F 78C7 AE83

* remotes/bonzini-gitlab/tags/for-upstream: (38 commits)
  meson: identify more sections of meson.build
  scsi/scsi_bus: fix races in REPORT LUNS
  virtio-scsi: use scsi_device_get
  scsi/scsi_bus: Add scsi_device_get
  scsi/scsi-bus: scsi_device_find: don't return unrealized devices
  device-core: use atomic_set on .realized property
  scsi: switch to bus->check_address
  device-core: use RCU for list of children of a bus
  device_core: use drain_call_rcu in in qmp_device_add
  scsi/scsi_bus: switch search direction in scsi_device_find
  qdev: add "check if address free" callback for buses
  qemu-iotests, qtest: rewrite test 067 as a qtest
  qtest: check that drives are really appearing and disappearing
  qtest: switch users back to qtest_qmp_receive
  device-plug-test: use qtest_qmp to send the device_del command
  qtest: remove qtest_qmp_receive_success
  qtest: Reintroduce qtest_qmp_receive with QMP event buffering
  qtest: rename qtest_qmp_receive to qtest_qmp_receive_dict
  meson.build: Re-enable KVM support for MIPS
  build-sys: fix git version from -version
  ...

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

3 files changed, 73 insertions, 34 deletions

diff --git a/hw/core/bus.c b/hw/core/bus.c
index 6b987b6..a048385 100644
--- a/hw/core/bus.c
+++ b/hw/core/bus.c
@@ -49,12 +49,14 @@ int qbus_walk_children(BusState *bus,
         }
     }
 
-    QTAILQ_FOREACH(kid, &bus->children, sibling) {
-        err = qdev_walk_children(kid->child,
-                                 pre_devfn, pre_busfn,
-                                 post_devfn, post_busfn, opaque);
-        if (err < 0) {
-            return err;
+    WITH_RCU_READ_LOCK_GUARD() {
+        QTAILQ_FOREACH_RCU(kid, &bus->children, sibling) {
+            err = qdev_walk_children(kid->child,
+                                     pre_devfn, pre_busfn,
+                                     post_devfn, post_busfn, opaque);
+            if (err < 0) {
+                return err;
+            }
         }
     }
 
@@ -90,8 +92,10 @@ static void bus_reset_child_foreach(Object *obj, ResettableChildCallback cb,
     BusState *bus = BUS(obj);
     BusChild *kid;
 
-    QTAILQ_FOREACH(kid, &bus->children, sibling) {
-        cb(OBJECT(kid->child), opaque, type);
+    WITH_RCU_READ_LOCK_GUARD() {
+        QTAILQ_FOREACH_RCU(kid, &bus->children, sibling) {
+            cb(OBJECT(kid->child), opaque, type);
+        }
     }
 }
 
@@ -194,9 +198,11 @@ static void bus_set_realized(Object *obj, bool value, Error **errp)
 
         /* TODO: recursive realization */
     } else if (!value && bus->realized) {
-        QTAILQ_FOREACH(kid, &bus->children, sibling) {
-            DeviceState *dev = kid->child;
-            qdev_unrealize(dev);
+        WITH_RCU_READ_LOCK_GUARD() {
+            QTAILQ_FOREACH_RCU(kid, &bus->children, sibling) {
+                DeviceState *dev = kid->child;
+                qdev_unrealize(dev);
+            }
         }
         if (bc->unrealize) {
             bc->unrealize(bus);
diff --git a/hw/core/meson.build b/hw/core/meson.build
index fc91f98..4a744f3 100644
--- a/hw/core/meson.build
+++ b/hw/core/meson.build
@@ -14,12 +14,6 @@ hwcore_files = files(
   'qdev-clock.c',
 )
 
-libhwcore = static_library('hwcore', sources: hwcore_files + genh,
-                           name_suffix: 'fa',
-                           build_by_default: false)
-hwcore = declare_dependency(link_whole: libhwcore)
-common_ss.add(hwcore)
-
 common_ss.add(files('cpu.c'))
 common_ss.add(when: 'CONFIG_FITLOADER', if_true: files('loader-fit.c'))
 common_ss.add(when: 'CONFIG_GENERIC_LOADER', if_true: files('generic-loader.c'))
diff --git a/hw/core/qdev.c b/hw/core/qdev.c
index 96772a1..fc4daa3 100644
--- a/hw/core/qdev.c
+++ b/hw/core/qdev.c
@@ -51,6 +51,12 @@ const VMStateDescription *qdev_get_vmsd(DeviceState *dev)
     return dc->vmsd;
 }
 
+static void bus_free_bus_child(BusChild *kid)
+{
+    object_unref(OBJECT(kid->child));
+    g_free(kid);
+}
+
 static void bus_remove_child(BusState *bus, DeviceState *child)
 {
     BusChild *kid;
@@ -60,15 +66,16 @@ static void bus_remove_child(BusState *bus, DeviceState *child)
             char name[32];
 
             snprintf(name, sizeof(name), "child[%d]", kid->index);
-            QTAILQ_REMOVE(&bus->children, kid, sibling);
+            QTAILQ_REMOVE_RCU(&bus->children, kid, sibling);
 
             bus->num_children--;
 
             /* This gives back ownership of kid->child back to us.  */
             object_property_del(OBJECT(bus), name);
-            object_unref(OBJECT(kid->child));
-            g_free(kid);
-            return;
+
+            /* free the bus kid, when it is safe to do so*/
+            call_rcu(kid, bus_free_bus_child, rcu);
+            break;
         }
     }
 }
@@ -83,7 +90,7 @@ static void bus_add_child(BusState *bus, DeviceState *child)
     kid->child = child;
     object_ref(OBJECT(kid->child));
 
-    QTAILQ_INSERT_HEAD(&bus->children, kid, sibling);
+    QTAILQ_INSERT_HEAD_RCU(&bus->children, kid, sibling);
 
     /* This transfers ownership of kid->child to the property.  */
     snprintf(name, sizeof(name), "child[%d]", kid->index);
@@ -94,13 +101,23 @@ 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 +143,7 @@ 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 +389,9 @@ 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);
     }
@@ -659,17 +679,19 @@ DeviceState *qdev_find_recursive(BusState *bus, const char *id)
     DeviceState *ret;
     BusState *child;
 
-    QTAILQ_FOREACH(kid, &bus->children, sibling) {
-        DeviceState *dev = kid->child;
+    WITH_RCU_READ_LOCK_GUARD() {
+        QTAILQ_FOREACH_RCU(kid, &bus->children, sibling) {
+            DeviceState *dev = kid->child;
 
-        if (dev->id && strcmp(dev->id, id) == 0) {
-            return dev;
-        }
+            if (dev->id && strcmp(dev->id, id) == 0) {
+                return dev;
+            }
 
-        QLIST_FOREACH(child, &dev->child_bus, sibling) {
-            ret = qdev_find_recursive(child, id);
-            if (ret) {
-                return ret;
+            QLIST_FOREACH(child, &dev->child_bus, sibling) {
+                ret = qdev_find_recursive(child, id);
+                if (ret) {
+                    return ret;
+                }
             }
         }
     }
@@ -924,7 +946,25 @@ static void device_set_realized(Object *obj, bool value, Error **errp)
             }
        }
 
+       qatomic_store_release(&dev->realized, value);
+
     } else if (!value && dev->realized) {
+
+        /*
+         * Change the value so that any concurrent users are aware
+         * that the device is going to be unrealized
+         *
+         * TODO: change .realized property to enum that states
+         * each phase of the device realization/unrealization
+         */
+
+        qatomic_set(&dev->realized, value);
+        /*
+         * Ensure that concurrent users see this update prior to
+         * any other changes done by unrealize.
+         */
+        smp_wmb();
+
         QLIST_FOREACH(bus, &dev->child_bus, sibling) {
             qbus_unrealize(bus);
         }
@@ -939,7 +979,6 @@ static void device_set_realized(Object *obj, bool value, Error **errp)
     }
 
     assert(local_err == NULL);
-    dev->realized = value;
     return;
 
 child_realize_fail: