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>

10 files changed, 288 insertions, 146 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:
diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index a160a9d..277289d 100644
--- 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/nvram/fw_cfg-interface.c b/hw/nvram/fw_cfg-interface.c
new file mode 100644
index 0000000..0e93fee
--- /dev/null
+++ b/hw/nvram/fw_cfg-interface.c
@@ -0,0 +1,23 @@
+/*
+ * QEMU Firmware configuration device emulation (QOM interfaces)
+ *
+ * Copyright 2020 Red Hat, Inc.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "hw/nvram/fw_cfg.h"
+
+static const TypeInfo fw_cfg_data_generator_interface_info = {
+    .parent = TYPE_INTERFACE,
+    .name = TYPE_FW_CFG_DATA_GENERATOR_INTERFACE,
+    .class_size = sizeof(FWCfgDataGeneratorClass),
+};
+
+static void fw_cfg_register_interfaces(void)
+{
+    type_register_static(&fw_cfg_data_generator_interface_info);
+}
+
+type_init(fw_cfg_register_interfaces)
diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c
index 0e95d05..08539a1 100644
--- a/hw/nvram/fw_cfg.c
+++ b/hw/nvram/fw_cfg.c
@@ -1360,18 +1360,11 @@ static const TypeInfo fw_cfg_mem_info = {
     .class_init    = fw_cfg_mem_class_init,
 };
 
-static const TypeInfo fw_cfg_data_generator_interface_info = {
-    .parent = TYPE_INTERFACE,
-    .name = TYPE_FW_CFG_DATA_GENERATOR_INTERFACE,
-    .class_size = sizeof(FWCfgDataGeneratorClass),
-};
-
 static void fw_cfg_register_types(void)
 {
     type_register_static(&fw_cfg_info);
     type_register_static(&fw_cfg_io_info);
     type_register_static(&fw_cfg_mem_info);
-    type_register_static(&fw_cfg_data_generator_interface_info);
 }
 
 type_init(fw_cfg_register_types)
diff --git a/hw/nvram/meson.build b/hw/nvram/meson.build
index 1f2ed01..fd2951a 100644
--- a/hw/nvram/meson.build
+++ b/hw/nvram/meson.build
@@ -1,3 +1,6 @@
+# QOM interfaces must be available anytime QOM is used.
+qom_ss.add(files('fw_cfg-interface.c'))
+
 softmmu_ss.add(files('fw_cfg.c'))
 softmmu_ss.add(when: 'CONFIG_CHRP_NVRAM', if_true: files('chrp_nvram.c'))
 softmmu_ss.add(when: 'CONFIG_DS1225Y', if_true: files('ds1225y.c'))
diff --git a/hw/scsi/scsi-bus.c b/hw/scsi/scsi-bus.c
index 3284a5d..b901e70 100644
--- a/hw/scsi/scsi-bus.c
+++ b/hw/scsi/scsi-bus.c
@@ -22,34 +22,67 @@ static void scsi_req_dequeue(SCSIRequest *req);
 static uint8_t *scsi_target_alloc_buf(SCSIRequest *req, size_t len);
 static void scsi_target_free_buf(SCSIRequest *req);
 
-static Property scsi_props[] = {
-    DEFINE_PROP_UINT32("channel", SCSIDevice, channel, 0),
-    DEFINE_PROP_UINT32("scsi-id", SCSIDevice, id, -1),
-    DEFINE_PROP_UINT32("lun", SCSIDevice, lun, -1),
-    DEFINE_PROP_END_OF_LIST(),
-};
+static int next_scsi_bus;
 
-static void scsi_bus_class_init(ObjectClass *klass, void *data)
+static SCSIDevice *do_scsi_device_find(SCSIBus *bus,
+                                       int channel, int id, int lun,
+                                       bool include_unrealized)
 {
-    BusClass *k = BUS_CLASS(klass);
-    HotplugHandlerClass *hc = HOTPLUG_HANDLER_CLASS(klass);
+    BusChild *kid;
+    SCSIDevice *retval = NULL;
 
-    k->get_dev_path = scsibus_get_dev_path;
-    k->get_fw_dev_path = scsibus_get_fw_dev_path;
-    hc->unplug = qdev_simple_device_unplug_cb;
+    QTAILQ_FOREACH_RCU(kid, &bus->qbus.children, sibling) {
+        DeviceState *qdev = kid->child;
+        SCSIDevice *dev = SCSI_DEVICE(qdev);
+
+        if (dev->channel == channel && dev->id == id) {
+            if (dev->lun == lun) {
+                retval = dev;
+                break;
+            }
+
+            /*
+             * If we don't find exact match (channel/bus/lun),
+             * we will return the first device which matches channel/bus
+             */
+
+            if (!retval) {
+                retval = dev;
+            }
+        }
+    }
+
+    /*
+     * This function might run on the IO thread and we might race against
+     * main thread hot-plugging the device.
+     * We assume that as soon as .realized is set to true we can let
+     * the user access the device.
+     */
+
+    if (retval && !include_unrealized &&
+        !qatomic_load_acquire(&retval->qdev.realized)) {
+        retval = NULL;
+    }
+
+    return retval;
 }
 
-static const TypeInfo scsi_bus_info = {
-    .name = TYPE_SCSI_BUS,
-    .parent = TYPE_BUS,
-    .instance_size = sizeof(SCSIBus),
-    .class_init = scsi_bus_class_init,
-    .interfaces = (InterfaceInfo[]) {
-        { TYPE_HOTPLUG_HANDLER },
-        { }
+SCSIDevice *scsi_device_find(SCSIBus *bus, int channel, int id, int lun)
+{
+    RCU_READ_LOCK_GUARD();
+    return do_scsi_device_find(bus, channel, id, lun, false);
+}
+
+SCSIDevice *scsi_device_get(SCSIBus *bus, int channel, int id, int lun)
+{
+    SCSIDevice *d;
+    RCU_READ_LOCK_GUARD();
+    d = do_scsi_device_find(bus, channel, id, lun, false);
+    if (d) {
+        object_ref(d);
     }
-};
-static int next_scsi_bus;
+    return d;
+}
 
 static void scsi_device_realize(SCSIDevice *s, Error **errp)
 {
@@ -160,35 +193,71 @@ static void scsi_dma_restart_cb(void *opaque, int running, RunState state)
     }
 }
 
-static void scsi_qdev_realize(DeviceState *qdev, Error **errp)
+static bool scsi_bus_is_address_free(SCSIBus *bus,
+				     int channel, int target, int lun,
+				     SCSIDevice **p_dev)
 {
-    SCSIDevice *dev = SCSI_DEVICE(qdev);
-    SCSIBus *bus = DO_UPCAST(SCSIBus, qbus, dev->qdev.parent_bus);
     SCSIDevice *d;
-    Error *local_err = NULL;
+
+    RCU_READ_LOCK_GUARD();
+    d = do_scsi_device_find(bus, channel, target, lun, true);
+    if (d && d->lun == lun) {
+        if (p_dev) {
+            *p_dev = d;
+        }
+        return false;
+    }
+    if (p_dev) {
+        *p_dev = NULL;
+    }
+    return true;
+}
+
+static bool scsi_bus_check_address(BusState *qbus, DeviceState *qdev, Error **errp)
+{
+    SCSIDevice *dev = SCSI_DEVICE(qdev);
+    SCSIBus *bus = SCSI_BUS(qbus);
 
     if (dev->channel > bus->info->max_channel) {
         error_setg(errp, "bad scsi channel id: %d", dev->channel);
-        return;
+        return false;
     }
     if (dev->id != -1 && dev->id > bus->info->max_target) {
         error_setg(errp, "bad scsi device id: %d", dev->id);
-        return;
+        return false;
     }
     if (dev->lun != -1 && dev->lun > bus->info->max_lun) {
         error_setg(errp, "bad scsi device lun: %d", dev->lun);
-        return;
+        return false;
+    }
+
+    if (dev->id != -1 && dev->lun != -1) {
+        SCSIDevice *d;
+        if (!scsi_bus_is_address_free(bus, dev->channel, dev->id, dev->lun, &d)) {
+            error_setg(errp, "lun already used by '%s'", d->qdev.id);
+            return false;
+        }
     }
 
+    return true;
+}
+
+static void scsi_qdev_realize(DeviceState *qdev, Error **errp)
+{
+    SCSIDevice *dev = SCSI_DEVICE(qdev);
+    SCSIBus *bus = DO_UPCAST(SCSIBus, qbus, dev->qdev.parent_bus);
+    bool is_free;
+    Error *local_err = NULL;
+
     if (dev->id == -1) {
         int id = -1;
         if (dev->lun == -1) {
             dev->lun = 0;
         }
         do {
-            d = scsi_device_find(bus, dev->channel, ++id, dev->lun);
-        } while (d && d->lun == dev->lun && id < bus->info->max_target);
-        if (d && d->lun == dev->lun) {
+            is_free = scsi_bus_is_address_free(bus, dev->channel, ++id, dev->lun, NULL);
+        } while (!is_free && id < bus->info->max_target);
+        if (!is_free) {
             error_setg(errp, "no free target");
             return;
         }
@@ -196,20 +265,13 @@ static void scsi_qdev_realize(DeviceState *qdev, Error **errp)
     } else if (dev->lun == -1) {
         int lun = -1;
         do {
-            d = scsi_device_find(bus, dev->channel, dev->id, ++lun);
-        } while (d && d->lun == lun && lun < bus->info->max_lun);
-        if (d && d->lun == lun) {
+            is_free = scsi_bus_is_address_free(bus, dev->channel, dev->id, ++lun, NULL);
+        } while (!is_free && lun < bus->info->max_lun);
+        if (!is_free) {
             error_setg(errp, "no free lun");
             return;
         }
         dev->lun = lun;
-    } else {
-        d = scsi_device_find(bus, dev->channel, dev->id, dev->lun);
-        assert(d);
-        if (d->lun == dev->lun && dev != d) {
-            error_setg(errp, "lun already used by '%s'", d->qdev.id);
-            return;
-        }
     }
 
     QTAILQ_INIT(&dev->requests);
@@ -376,19 +438,23 @@ struct SCSITargetReq {
 static void store_lun(uint8_t *outbuf, int lun)
 {
     if (lun < 256) {
+        /* Simple logical unit addressing method*/
+        outbuf[0] = 0;
         outbuf[1] = lun;
-        return;
+    } else {
+        /* Flat space addressing method */
+        outbuf[0] = 0x40 | (lun >> 8);
+        outbuf[1] = (lun & 255);
     }
-    outbuf[1] = (lun & 255);
-    outbuf[0] = (lun >> 8) | 0x40;
 }
 
 static bool scsi_target_emulate_report_luns(SCSITargetReq *r)
 {
     BusChild *kid;
-    int i, len, n;
     int channel, id;
-    bool found_lun0;
+    uint8_t tmp[8] = {0};
+    int len = 0;
+    GByteArray *buf;
 
     if (r->req.cmd.xfer < 16) {
         return false;
@@ -396,42 +462,40 @@ static bool scsi_target_emulate_report_luns(SCSITargetReq *r)
     if (r->req.cmd.buf[2] > 2) {
         return false;
     }
+
+    /* reserve space for 63 LUNs*/
+    buf = g_byte_array_sized_new(512);
+
     channel = r->req.dev->channel;
     id = r->req.dev->id;
-    found_lun0 = false;
-    n = 0;
-    QTAILQ_FOREACH(kid, &r->req.bus->qbus.children, sibling) {
-        DeviceState *qdev = kid->child;
-        SCSIDevice *dev = SCSI_DEVICE(qdev);
 
-        if (dev->channel == channel && dev->id == id) {
-            if (dev->lun == 0) {
-                found_lun0 = true;
-            }
-            n += 8;
-        }
-    }
-    if (!found_lun0) {
-        n += 8;
-    }
+    /* add size (will be updated later to correct value */
+    g_byte_array_append(buf, tmp, 8);
+    len += 8;
 
-    scsi_target_alloc_buf(&r->req, n + 8);
+    /* add LUN0 */
+    g_byte_array_append(buf, tmp, 8);
+    len += 8;
 
-    len = MIN(n + 8, r->req.cmd.xfer & ~7);
-    memset(r->buf, 0, len);
-    stl_be_p(&r->buf[0], n);
-    i = found_lun0 ? 8 : 16;
-    QTAILQ_FOREACH(kid, &r->req.bus->qbus.children, sibling) {
-        DeviceState *qdev = kid->child;
-        SCSIDevice *dev = SCSI_DEVICE(qdev);
+    WITH_RCU_READ_LOCK_GUARD() {
+        QTAILQ_FOREACH_RCU(kid, &r->req.bus->qbus.children, sibling) {
+            DeviceState *qdev = kid->child;
+            SCSIDevice *dev = SCSI_DEVICE(qdev);
 
-        if (dev->channel == channel && dev->id == id) {
-            store_lun(&r->buf[i], dev->lun);
-            i += 8;
+            if (dev->channel == channel && dev->id == id && dev->lun != 0) {
+                store_lun(tmp, dev->lun);
+                g_byte_array_append(buf, tmp, 8);
+                len += 8;
+            }
         }
     }
-    assert(i == n + 8);
-    r->len = len;
+
+    r->buf_len = len;
+    r->buf = g_byte_array_free(buf, FALSE);
+    r->len = MIN(len, r->req.cmd.xfer & ~7);
+
+    /* store the LUN list length */
+    stl_be_p(&r->buf[0], len - 8);
     return true;
 }
 
@@ -1567,25 +1631,6 @@ static char *scsibus_get_fw_dev_path(DeviceState *dev)
                            qdev_fw_name(dev), d->id, d->lun);
 }
 
-SCSIDevice *scsi_device_find(SCSIBus *bus, int channel, int id, int lun)
-{
-    BusChild *kid;
-    SCSIDevice *target_dev = NULL;
-
-    QTAILQ_FOREACH_REVERSE(kid, &bus->qbus.children, sibling) {
-        DeviceState *qdev = kid->child;
-        SCSIDevice *dev = SCSI_DEVICE(qdev);
-
-        if (dev->channel == channel && dev->id == id) {
-            if (dev->lun == lun) {
-                return dev;
-            }
-            target_dev = dev;
-        }
-    }
-    return target_dev;
-}
-
 /* SCSI request list.  For simplicity, pv points to the whole device */
 
 static int put_scsi_requests(QEMUFile *f, void *pv, size_t size,
@@ -1709,6 +1754,13 @@ const VMStateDescription vmstate_scsi_device = {
     }
 };
 
+static Property scsi_props[] = {
+    DEFINE_PROP_UINT32("channel", SCSIDevice, channel, 0),
+    DEFINE_PROP_UINT32("scsi-id", SCSIDevice, id, -1),
+    DEFINE_PROP_UINT32("lun", SCSIDevice, lun, -1),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
 static void scsi_device_class_init(ObjectClass *klass, void *data)
 {
     DeviceClass *k = DEVICE_CLASS(klass);
@@ -1739,6 +1791,28 @@ static const TypeInfo scsi_device_type_info = {
     .instance_init = scsi_dev_instance_init,
 };
 
+static void scsi_bus_class_init(ObjectClass *klass, void *data)
+{
+    BusClass *k = BUS_CLASS(klass);
+    HotplugHandlerClass *hc = HOTPLUG_HANDLER_CLASS(klass);
+
+    k->get_dev_path = scsibus_get_dev_path;
+    k->get_fw_dev_path = scsibus_get_fw_dev_path;
+    k->check_address = scsi_bus_check_address;
+    hc->unplug = qdev_simple_device_unplug_cb;
+}
+
+static const TypeInfo scsi_bus_info = {
+    .name = TYPE_SCSI_BUS,
+    .parent = TYPE_BUS,
+    .instance_size = sizeof(SCSIBus),
+    .class_init = scsi_bus_class_init,
+    .interfaces = (InterfaceInfo[]) {
+        { TYPE_HOTPLUG_HANDLER },
+        { }
+    }
+};
+
 static void scsi_register_types(void)
 {
     type_register_static(&scsi_bus_info);
diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index 3a71ea7..3db9a8a 100644
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -33,7 +33,7 @@ static inline int virtio_scsi_get_lun(uint8_t *lun)
     return ((lun[2] << 8) | lun[3]) & 0x3FFF;
 }
 
-static inline SCSIDevice *virtio_scsi_device_find(VirtIOSCSI *s, uint8_t *lun)
+static inline SCSIDevice *virtio_scsi_device_get(VirtIOSCSI *s, uint8_t *lun)
 {
     if (lun[0] != 1) {
         return NULL;
@@ -41,7 +41,7 @@ static inline SCSIDevice *virtio_scsi_device_find(VirtIOSCSI *s, uint8_t *lun)
     if (lun[2] != 0 && !(lun[2] >= 0x40 && lun[2] < 0x80)) {
         return NULL;
     }
-    return scsi_device_find(&s->bus, 0, lun[1], virtio_scsi_get_lun(lun));
+    return scsi_device_get(&s->bus, 0, lun[1], virtio_scsi_get_lun(lun));
 }
 
 void virtio_scsi_init_req(VirtIOSCSI *s, VirtQueue *vq, VirtIOSCSIReq *req)
@@ -256,7 +256,7 @@ static inline void virtio_scsi_ctx_check(VirtIOSCSI *s, SCSIDevice *d)
  *  case of async cancellation. */
 static int virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCSIReq *req)
 {
-    SCSIDevice *d = virtio_scsi_device_find(s, req->req.tmf.lun);
+    SCSIDevice *d = virtio_scsi_device_get(s, req->req.tmf.lun);
     SCSIRequest *r, *next;
     BusChild *kid;
     int target;
@@ -367,12 +367,16 @@ static int virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCSIReq *req)
     case VIRTIO_SCSI_T_TMF_I_T_NEXUS_RESET:
         target = req->req.tmf.lun[1];
         s->resetting++;
-        QTAILQ_FOREACH(kid, &s->bus.qbus.children, sibling) {
-             d = SCSI_DEVICE(kid->child);
-             if (d->channel == 0 && d->id == target) {
-                qdev_reset_all(&d->qdev);
-             }
+
+        rcu_read_lock();
+        QTAILQ_FOREACH_RCU(kid, &s->bus.qbus.children, sibling) {
+            SCSIDevice *d1 = SCSI_DEVICE(kid->child);
+            if (d1->channel == 0 && d1->id == target) {
+                qdev_reset_all(&d1->qdev);
+            }
         }
+        rcu_read_unlock();
+
         s->resetting--;
         break;
 
@@ -382,14 +386,17 @@ static int virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCSIReq *req)
         break;
     }
 
+    object_unref(OBJECT(d));
     return ret;
 
 incorrect_lun:
     req->resp.tmf.response = VIRTIO_SCSI_S_INCORRECT_LUN;
+    object_unref(OBJECT(d));
     return ret;
 
 fail:
     req->resp.tmf.response = VIRTIO_SCSI_S_BAD_TARGET;
+    object_unref(OBJECT(d));
     return ret;
 }
 
@@ -560,7 +567,7 @@ static int virtio_scsi_handle_cmd_req_prepare(VirtIOSCSI *s, VirtIOSCSIReq *req)
         }
     }
 
-    d = virtio_scsi_device_find(s, req->req.cmd.lun);
+    d = virtio_scsi_device_get(s, req->req.cmd.lun);
     if (!d) {
         req->resp.cmd.response = VIRTIO_SCSI_S_BAD_TARGET;
         virtio_scsi_complete_cmd_req(req);
@@ -576,10 +583,12 @@ static int virtio_scsi_handle_cmd_req_prepare(VirtIOSCSI *s, VirtIOSCSIReq *req)
             req->sreq->cmd.xfer > req->qsgl.size)) {
         req->resp.cmd.response = VIRTIO_SCSI_S_OVERRUN;
         virtio_scsi_complete_cmd_req(req);
+        object_unref(OBJECT(d));
         return -ENOBUFS;
     }
     scsi_req_ref(req->sreq);
     blk_io_plug(d->conf.blk);
+    object_unref(OBJECT(d));
     return 0;
 }
 
diff --git a/hw/sd/core.c b/hw/sd/core.c
index 957d116..08c93b5 100644
--- 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);
 }