qapi: introduce device-sync-config
Add command to sync config from vhost-user backend to the device. It
may be helpful when VHOST_USER_SLAVE_CONFIG_CHANGE_MSG failed or not
triggered interrupt to the guest or just not available (not supported
by vhost-user server).
Command result is racy if allow it during migration. Let's not allow
that.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Acked-by: Raphael Norwitz <raphael@enfabrica.net>
Message-Id: <20240920094936.450987-4-vsementsov@yandex-team.ru>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
diff --git a/hw/block/vhost-user-blk.c b/hw/block/vhost-user-blk.c
index 48b3dab..7996e49 100644
--- a/hw/block/vhost-user-blk.c
+++ b/hw/block/vhost-user-blk.c
@@ -591,6 +591,7 @@
device_class_set_props(dc, vhost_user_blk_properties);
dc->vmsd = &vmstate_vhost_user_blk;
+ dc->sync_config = vhost_user_blk_sync_config;
set_bit(DEVICE_CATEGORY_STORAGE, dc->categories);
vdc->realize = vhost_user_blk_device_realize;
vdc->unrealize = vhost_user_blk_device_unrealize;
diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index 4d832fe..c5a809b 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -2385,6 +2385,14 @@
vpciklass->parent_dc_realize(qdev, errp);
}
+static int virtio_pci_sync_config(DeviceState *dev, Error **errp)
+{
+ VirtIOPCIProxy *proxy = VIRTIO_PCI(dev);
+ VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
+
+ return qdev_sync_config(DEVICE(vdev), errp);
+}
+
static void virtio_pci_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
@@ -2401,6 +2409,7 @@
device_class_set_parent_realize(dc, virtio_pci_dc_realize,
&vpciklass->parent_dc_realize);
rc->phases.hold = virtio_pci_bus_reset_hold;
+ dc->sync_config = virtio_pci_sync_config;
}
static const TypeInfo virtio_pci_info = {
diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
index aa97c34..9491485 100644
--- a/include/hw/qdev-core.h
+++ b/include/hw/qdev-core.h
@@ -95,6 +95,7 @@
typedef void (*DeviceReset)(DeviceState *dev);
typedef void (*BusRealize)(BusState *bus, Error **errp);
typedef void (*BusUnrealize)(BusState *bus);
+typedef int (*DeviceSyncConfig)(DeviceState *dev, Error **errp);
/**
* struct DeviceClass - The base class for all devices.
@@ -103,6 +104,9 @@
* property is changed to %true.
* @unrealize: Callback function invoked when the #DeviceState:realized
* property is changed to %false.
+ * @sync_config: Callback function invoked when QMP command device-sync-config
+ * is called. Should synchronize device configuration from host to guest part
+ * and notify the guest about the change.
* @hotpluggable: indicates if #DeviceClass is hotpluggable, available
* as readonly "hotpluggable" property of #DeviceState instance
*
@@ -162,6 +166,7 @@
DeviceReset legacy_reset;
DeviceRealize realize;
DeviceUnrealize unrealize;
+ DeviceSyncConfig sync_config;
/**
* @vmsd: device state serialisation description for
@@ -547,6 +552,7 @@
*/
HotplugHandler *qdev_get_hotplug_handler(DeviceState *dev);
void qdev_unplug(DeviceState *dev, Error **errp);
+int qdev_sync_config(DeviceState *dev, Error **errp);
void qdev_simple_device_unplug_cb(HotplugHandler *hotplug_dev,
DeviceState *dev, Error **errp);
void qdev_machine_creation_done(void);
diff --git a/qapi/qdev.json b/qapi/qdev.json
index 53d147c..2a58112 100644
--- a/qapi/qdev.json
+++ b/qapi/qdev.json
@@ -163,3 +163,27 @@
##
{ 'event': 'DEVICE_UNPLUG_GUEST_ERROR',
'data': { '*device': 'str', 'path': 'str' } }
+
+##
+# @device-sync-config:
+#
+# Synchronize device configuration from host to guest part. First,
+# copy the configuration from the host part (backend) to the guest
+# part (frontend). Then notify guest software that device
+# configuration changed.
+#
+# The command may be used to notify the guest about block device
+# capcity change. Currently only vhost-user-blk device supports
+# this.
+#
+# @id: the device's ID or QOM path
+#
+# Features:
+#
+# @unstable: The command is experimental.
+#
+# Since: 9.1
+##
+{ 'command': 'device-sync-config',
+ 'features': [ 'unstable' ],
+ 'data': {'id': 'str'} }
diff --git a/system/qdev-monitor.c b/system/qdev-monitor.c
index 6671137..1274560 100644
--- a/system/qdev-monitor.c
+++ b/system/qdev-monitor.c
@@ -23,6 +23,7 @@
#include "monitor/monitor.h"
#include "monitor/qdev.h"
#include "sysemu/arch_init.h"
+#include "sysemu/runstate.h"
#include "qapi/error.h"
#include "qapi/qapi-commands-qdev.h"
#include "qapi/qmp/dispatch.h"
@@ -977,6 +978,43 @@
}
}
+int qdev_sync_config(DeviceState *dev, Error **errp)
+{
+ DeviceClass *dc = DEVICE_GET_CLASS(dev);
+
+ if (!dc->sync_config) {
+ error_setg(errp, "device-sync-config is not supported for '%s'",
+ object_get_typename(OBJECT(dev)));
+ return -ENOTSUP;
+ }
+
+ return dc->sync_config(dev, errp);
+}
+
+void qmp_device_sync_config(const char *id, Error **errp)
+{
+ DeviceState *dev;
+
+ /*
+ * During migration there is a race between syncing`configuration
+ * and migrating it (if migrate first, that target would get
+ * outdated version), so let's just not allow it.
+ */
+
+ if (migration_is_running()) {
+ error_setg(errp, "Config synchronization is not allowed "
+ "during migration");
+ return;
+ }
+
+ dev = find_device_state(id, true, errp);
+ if (!dev) {
+ return;
+ }
+
+ qdev_sync_config(dev, errp);
+}
+
void hmp_device_add(Monitor *mon, const QDict *qdict)
{
Error *err = NULL;
