Re: [PATCH v4 3/3] qapi: introduce device-sync-config
Vladimir Sementsov-Ogievskiy writes:
> On 30.04.24 11:31, Vladimir Sementsov-Ogievskiy wrote:
>> On 30.04.24 11:19, Markus Armbruster wrote:
>>> Vladimir Sementsov-Ogievskiy writes:
>>>
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 allow the
sync only in RUNNING state.
Signed-off-by: Vladimir Sementsov-Ogievskiy
[...]
diff --git a/system/qdev-monitor.c b/system/qdev-monitor.c
index 264978aa40..47bfc0506e 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"
@@ -971,6 +972,53 @@ void qmp_device_del(const char *id, Error **errp)
}
}
+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+ * migrating it (if migrate first, that target would get outdated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.
>>>
>>> Wrap comment lines around column 70 for legibility, please.
>>>
+ *
+ * Moreover, let's not rely on setting up interrupts in paused
+ * state, which may be a part of migration process.
>>>
>>> We discussed this in review of v3. You wanted to check whether the
>>> problem is real. Is it?
>>
>> We discussed it later than I've sent v4 :) No, I didn't check yet.
>
> Checked. Seems this works (in scheme pause -> migrate -> resume, interrupts
> are migrated and triggered on target after resume), so my doubt was wrong.
Thanks!
[...]
Re: [PATCH v4 3/3] qapi: introduce device-sync-config
On 30.04.24 11:31, Vladimir Sementsov-Ogievskiy wrote:
On 30.04.24 11:19, Markus Armbruster wrote:
Vladimir Sementsov-Ogievskiy writes:
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 allow the
sync only in RUNNING state.
Signed-off-by: Vladimir Sementsov-Ogievskiy
---
hw/block/vhost-user-blk.c | 1 +
hw/virtio/virtio-pci.c | 9
include/hw/qdev-core.h | 3 +++
qapi/qdev.json | 23 +++
system/qdev-monitor.c | 48 +++
5 files changed, 84 insertions(+)
diff --git a/hw/block/vhost-user-blk.c b/hw/block/vhost-user-blk.c
index 091d2c6acf..2f301f380c 100644
--- a/hw/block/vhost-user-blk.c
+++ b/hw/block/vhost-user-blk.c
@@ -588,6 +588,7 @@ static void vhost_user_blk_class_init(ObjectClass *klass,
void *data)
device_class_set_props(dc, vhost_user_blk_properties);
dc->vmsd = _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 b1d02f4b3d..0d91e8b5dc 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -2351,6 +2351,14 @@ static void virtio_pci_dc_realize(DeviceState *qdev,
Error **errp)
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(>bus);
+
+ return qdev_sync_config(DEVICE(vdev), errp);
+}
+
static void virtio_pci_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
@@ -2367,6 +2375,7 @@ static void virtio_pci_class_init(ObjectClass *klass,
void *data)
device_class_set_parent_realize(dc, virtio_pci_dc_realize,
>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 9228e96c87..87135bdcdf 100644
--- a/include/hw/qdev-core.h
+++ b/include/hw/qdev-core.h
@@ -95,6 +95,7 @@ typedef void (*DeviceUnrealize)(DeviceState *dev);
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.
@@ -162,6 +163,7 @@ struct DeviceClass {
DeviceReset reset;
DeviceRealize realize;
DeviceUnrealize unrealize;
+ DeviceSyncConfig sync_config;
/**
* @vmsd: device state serialisation description for
@@ -546,6 +548,7 @@ bool qdev_hotplug_allowed(DeviceState *dev, Error **errp);
*/
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 facaa0bc6a..fc5e125a45 100644
--- a/qapi/qdev.json
+++ b/qapi/qdev.json
@@ -161,3 +161,26 @@
##
{ '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.
Blank line here, please.
+# 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 264978aa40..47bfc0506e 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"
@@ -971,6 +972,53 @@ void qmp_device_del(const char *id, Error **errp)
}
}
+int qdev_sync_config(DeviceState *dev, Error **errp)
+{
+ DeviceClass *dc = DEVICE_GET_CLASS(dev);
+
+
Re: [PATCH v4 3/3] qapi: introduce device-sync-config
On 30.04.24 11:19, Markus Armbruster wrote:
Vladimir Sementsov-Ogievskiy writes:
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 allow the
sync only in RUNNING state.
Signed-off-by: Vladimir Sementsov-Ogievskiy
---
hw/block/vhost-user-blk.c | 1 +
hw/virtio/virtio-pci.c| 9
include/hw/qdev-core.h| 3 +++
qapi/qdev.json| 23 +++
system/qdev-monitor.c | 48 +++
5 files changed, 84 insertions(+)
diff --git a/hw/block/vhost-user-blk.c b/hw/block/vhost-user-blk.c
index 091d2c6acf..2f301f380c 100644
--- a/hw/block/vhost-user-blk.c
+++ b/hw/block/vhost-user-blk.c
@@ -588,6 +588,7 @@ static void vhost_user_blk_class_init(ObjectClass *klass,
void *data)
device_class_set_props(dc, vhost_user_blk_properties);
dc->vmsd = _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 b1d02f4b3d..0d91e8b5dc 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -2351,6 +2351,14 @@ static void virtio_pci_dc_realize(DeviceState *qdev,
Error **errp)
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(>bus);
+
+return qdev_sync_config(DEVICE(vdev), errp);
+}
+
static void virtio_pci_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
@@ -2367,6 +2375,7 @@ static void virtio_pci_class_init(ObjectClass *klass,
void *data)
device_class_set_parent_realize(dc, virtio_pci_dc_realize,
>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 9228e96c87..87135bdcdf 100644
--- a/include/hw/qdev-core.h
+++ b/include/hw/qdev-core.h
@@ -95,6 +95,7 @@ typedef void (*DeviceUnrealize)(DeviceState *dev);
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.
@@ -162,6 +163,7 @@ struct DeviceClass {
DeviceReset reset;
DeviceRealize realize;
DeviceUnrealize unrealize;
+DeviceSyncConfig sync_config;
/**
* @vmsd: device state serialisation description for
@@ -546,6 +548,7 @@ bool qdev_hotplug_allowed(DeviceState *dev, Error **errp);
*/
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 facaa0bc6a..fc5e125a45 100644
--- a/qapi/qdev.json
+++ b/qapi/qdev.json
@@ -161,3 +161,26 @@
##
{ '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.
Blank line here, please.
+# 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 264978aa40..47bfc0506e 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"
@@ -971,6 +972,53 @@ void qmp_device_del(const char *id, Error **errp)
}
}
+int qdev_sync_config(DeviceState *dev, Error **errp)
+{
+DeviceClass *dc = DEVICE_GET_CLASS(dev);
+
+if (!dc->sync_config) {
+
Re: [PATCH v4 3/3] qapi: introduce device-sync-config
Vladimir Sementsov-Ogievskiy writes:
> 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 allow the
> sync only in RUNNING state.
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy
> ---
> hw/block/vhost-user-blk.c | 1 +
> hw/virtio/virtio-pci.c| 9
> include/hw/qdev-core.h| 3 +++
> qapi/qdev.json| 23 +++
> system/qdev-monitor.c | 48 +++
> 5 files changed, 84 insertions(+)
>
> diff --git a/hw/block/vhost-user-blk.c b/hw/block/vhost-user-blk.c
> index 091d2c6acf..2f301f380c 100644
> --- a/hw/block/vhost-user-blk.c
> +++ b/hw/block/vhost-user-blk.c
> @@ -588,6 +588,7 @@ static void vhost_user_blk_class_init(ObjectClass *klass,
> void *data)
>
> device_class_set_props(dc, vhost_user_blk_properties);
> dc->vmsd = _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 b1d02f4b3d..0d91e8b5dc 100644
> --- a/hw/virtio/virtio-pci.c
> +++ b/hw/virtio/virtio-pci.c
> @@ -2351,6 +2351,14 @@ static void virtio_pci_dc_realize(DeviceState *qdev,
> Error **errp)
> 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(>bus);
> +
> +return qdev_sync_config(DEVICE(vdev), errp);
> +}
> +
> static void virtio_pci_class_init(ObjectClass *klass, void *data)
> {
> DeviceClass *dc = DEVICE_CLASS(klass);
> @@ -2367,6 +2375,7 @@ static void virtio_pci_class_init(ObjectClass *klass,
> void *data)
> device_class_set_parent_realize(dc, virtio_pci_dc_realize,
> >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 9228e96c87..87135bdcdf 100644
> --- a/include/hw/qdev-core.h
> +++ b/include/hw/qdev-core.h
> @@ -95,6 +95,7 @@ typedef void (*DeviceUnrealize)(DeviceState *dev);
> 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.
> @@ -162,6 +163,7 @@ struct DeviceClass {
> DeviceReset reset;
> DeviceRealize realize;
> DeviceUnrealize unrealize;
> +DeviceSyncConfig sync_config;
>
> /**
> * @vmsd: device state serialisation description for
> @@ -546,6 +548,7 @@ bool qdev_hotplug_allowed(DeviceState *dev, Error **errp);
> */
> 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 facaa0bc6a..fc5e125a45 100644
> --- a/qapi/qdev.json
> +++ b/qapi/qdev.json
> @@ -161,3 +161,26 @@
> ##
> { '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.
Blank line here, please.
> +# 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 264978aa40..47bfc0506e 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"
> @@ -971,6 +972,53 @@ void qmp_device_del(const char *id, Error **errp)
[PATCH v4 3/3] 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 allow the
sync only in RUNNING state.
Signed-off-by: Vladimir Sementsov-Ogievskiy
---
hw/block/vhost-user-blk.c | 1 +
hw/virtio/virtio-pci.c| 9
include/hw/qdev-core.h| 3 +++
qapi/qdev.json| 23 +++
system/qdev-monitor.c | 48 +++
5 files changed, 84 insertions(+)
diff --git a/hw/block/vhost-user-blk.c b/hw/block/vhost-user-blk.c
index 091d2c6acf..2f301f380c 100644
--- a/hw/block/vhost-user-blk.c
+++ b/hw/block/vhost-user-blk.c
@@ -588,6 +588,7 @@ static void vhost_user_blk_class_init(ObjectClass *klass,
void *data)
device_class_set_props(dc, vhost_user_blk_properties);
dc->vmsd = _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 b1d02f4b3d..0d91e8b5dc 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -2351,6 +2351,14 @@ static void virtio_pci_dc_realize(DeviceState *qdev,
Error **errp)
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(>bus);
+
+return qdev_sync_config(DEVICE(vdev), errp);
+}
+
static void virtio_pci_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
@@ -2367,6 +2375,7 @@ static void virtio_pci_class_init(ObjectClass *klass,
void *data)
device_class_set_parent_realize(dc, virtio_pci_dc_realize,
>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 9228e96c87..87135bdcdf 100644
--- a/include/hw/qdev-core.h
+++ b/include/hw/qdev-core.h
@@ -95,6 +95,7 @@ typedef void (*DeviceUnrealize)(DeviceState *dev);
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.
@@ -162,6 +163,7 @@ struct DeviceClass {
DeviceReset reset;
DeviceRealize realize;
DeviceUnrealize unrealize;
+DeviceSyncConfig sync_config;
/**
* @vmsd: device state serialisation description for
@@ -546,6 +548,7 @@ bool qdev_hotplug_allowed(DeviceState *dev, Error **errp);
*/
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 facaa0bc6a..fc5e125a45 100644
--- a/qapi/qdev.json
+++ b/qapi/qdev.json
@@ -161,3 +161,26 @@
##
{ '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 264978aa40..47bfc0506e 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"
@@ -971,6 +972,53 @@ void qmp_device_del(const char *id, Error **errp)
}
}
+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
