[PATCH v7 0/3] vhost-user-blk: live resize additional APIs

[PATCH v7 0/3] vhost-user-blk: live resize additional APIs

[Vladimir Sementsov-Ogievskiy]

v7: update QAPI version 9.1 -> 9.2

Vladimir Sementsov-Ogievskiy (3):
  qdev-monitor: add option to report GenericError from find_device_state
  vhost-user-blk: split vhost_user_blk_sync_config()
  qapi: introduce device-sync-config

 hw/block/vhost-user-blk.c | 27 ++++++++++++++------
 hw/virtio/virtio-pci.c    |  9 +++++++
 include/hw/qdev-core.h    |  6 +++++
 qapi/qdev.json            | 24 ++++++++++++++++++
 system/qdev-monitor.c     | 53 ++++++++++++++++++++++++++++++++++++---
 5 files changed, 108 insertions(+), 11 deletions(-)

-- 
2.34.1

[PATCH v7 1/3] qdev-monitor: add option to report GenericError from find_device_state

[Vladimir Sementsov-Ogievskiy]

Here we just prepare for the following patch, making possible to report
GenericError as recommended.

This patch doesn't aim to prevent further use of DeviceNotFound by
future interfaces:

 - find_device_state() is used in blk_by_qdev_id() and qmp_get_blk()
   functions, which may lead to spread of DeviceNotFound anyway
 - also, nothing prevent simply copy-pasting find_device_state() calls
   with false argument

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Acked-by: Raphael Norwitz <raphael@enfabrica.net>
---
 system/qdev-monitor.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/system/qdev-monitor.c b/system/qdev-monitor.c
index 320c47b72d..2c76cef4d8 100644
--- a/system/qdev-monitor.c
+++ b/system/qdev-monitor.c
@@ -885,13 +885,20 @@ void qmp_device_add(QDict *qdict, QObject **ret_data, Error **errp)
     object_unref(OBJECT(dev));
 }
 
-static DeviceState *find_device_state(const char *id, Error **errp)
+/*
+ * Note that creating new APIs using error classes other than GenericError is
+ * not recommended. Set use_generic_error=true for new interfaces.
+ */
+static DeviceState *find_device_state(const char *id, bool use_generic_error,
+                                      Error **errp)
 {
     Object *obj = object_resolve_path_at(qdev_get_peripheral(), id);
     DeviceState *dev;
 
     if (!obj) {
-        error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND,
+        error_set(errp,
+                  (use_generic_error ?
+                   ERROR_CLASS_GENERIC_ERROR : ERROR_CLASS_DEVICE_NOT_FOUND),
                   "Device '%s' not found", id);
         return NULL;
     }
@@ -956,7 +963,7 @@ void qdev_unplug(DeviceState *dev, Error **errp)
 
 void qmp_device_del(const char *id, Error **errp)
 {
-    DeviceState *dev = find_device_state(id, errp);
+    DeviceState *dev = find_device_state(id, false, errp);
     if (dev != NULL) {
         if (dev->pending_deleted_event &&
             (dev->pending_deleted_expires_ms == 0 ||
@@ -1076,7 +1083,7 @@ BlockBackend *blk_by_qdev_id(const char *id, Error **errp)
 
     GLOBAL_STATE_CODE();
 
-    dev = find_device_state(id, errp);
+    dev = find_device_state(id, false, errp);
     if (dev == NULL) {
         return NULL;
     }
-- 
2.34.1

[PATCH v7 2/3] vhost-user-blk: split vhost_user_blk_sync_config()

[Vladimir Sementsov-Ogievskiy]

Split vhost_user_blk_sync_config() out from
vhost_user_blk_handle_config_change(), to be reused in the following
commit.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Acked-by: Raphael Norwitz <raphael@enfabrica.net>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
---
 hw/block/vhost-user-blk.c | 26 +++++++++++++++++++-------
 1 file changed, 19 insertions(+), 7 deletions(-)

diff --git a/hw/block/vhost-user-blk.c b/hw/block/vhost-user-blk.c
index 5b7f46bbb0..48b3dabb8d 100644
--- a/hw/block/vhost-user-blk.c
+++ b/hw/block/vhost-user-blk.c
@@ -90,27 +90,39 @@ static void vhost_user_blk_set_config(VirtIODevice *vdev, const uint8_t *config)
     s->blkcfg.wce = blkcfg->wce;
 }
 
+static int vhost_user_blk_sync_config(DeviceState *dev, Error **errp)
+{
+    int ret;
+    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
+    VHostUserBlk *s = VHOST_USER_BLK(vdev);
+
+    ret = vhost_dev_get_config(&s->dev, (uint8_t *)&s->blkcfg,
+                               vdev->config_len, errp);
+    if (ret < 0) {
+        return ret;
+    }
+
+    memcpy(vdev->config, &s->blkcfg, vdev->config_len);
+    virtio_notify_config(vdev);
+
+    return 0;
+}
+
 static int vhost_user_blk_handle_config_change(struct vhost_dev *dev)
 {
     int ret;
-    VirtIODevice *vdev = dev->vdev;
-    VHostUserBlk *s = VHOST_USER_BLK(dev->vdev);
     Error *local_err = NULL;
 
     if (!dev->started) {
         return 0;
     }
 
-    ret = vhost_dev_get_config(dev, (uint8_t *)&s->blkcfg,
-                               vdev->config_len, &local_err);
+    ret = vhost_user_blk_sync_config(DEVICE(dev->vdev), &local_err);
     if (ret < 0) {
         error_report_err(local_err);
         return ret;
     }
 
-    memcpy(dev->vdev->config, &s->blkcfg, vdev->config_len);
-    virtio_notify_config(dev->vdev);
-
     return 0;
 }
 
-- 
2.34.1

[PATCH v7 3/3] qapi: introduce device-sync-config

[Vladimir Sementsov-Ogievskiy]

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>
---
 hw/block/vhost-user-blk.c |  1 +
 hw/virtio/virtio-pci.c    |  9 +++++++++
 include/hw/qdev-core.h    |  6 ++++++
 qapi/qdev.json            | 24 ++++++++++++++++++++++++
 system/qdev-monitor.c     | 38 ++++++++++++++++++++++++++++++++++++++
 5 files changed, 78 insertions(+)

diff --git a/hw/block/vhost-user-blk.c b/hw/block/vhost-user-blk.c
index 48b3dabb8d..7996e49821 100644
--- a/hw/block/vhost-user-blk.c
+++ b/hw/block/vhost-user-blk.c
@@ -591,6 +591,7 @@ static void vhost_user_blk_class_init(ObjectClass *klass, void *data)
 
     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 4d832fe845..c5a809b956 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -2385,6 +2385,14 @@ 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(&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 @@ static void virtio_pci_class_init(ObjectClass *klass, void *data)
     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 aa97c34a4b..94914858d8 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.
@@ -103,6 +104,9 @@ typedef void (*BusUnrealize)(BusState *bus);
  * 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 @@ struct DeviceClass {
     DeviceReset legacy_reset;
     DeviceRealize realize;
     DeviceUnrealize unrealize;
+    DeviceSyncConfig sync_config;
 
     /**
      * @vmsd: device state serialisation description for
@@ -547,6 +552,7 @@ 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 53d147c7b4..25cbcf977b 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: 9.2
+##
+{ 'command': 'device-sync-config',
+  'features': [ 'unstable' ],
+  'data': {'id': 'str'} }
diff --git a/system/qdev-monitor.c b/system/qdev-monitor.c
index 2c76cef4d8..d25325c4e3 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 @@ 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.
+     */
+
+    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;
-- 
2.34.1

Re: [PATCH v7 0/3] vhost-user-blk: live resize additional APIs

[Michael S. Tsirkin]

On Wed, Nov 06, 2024 at 02:18:34PM +0300, Vladimir Sementsov-Ogievskiy wrote:
> v7: update QAPI version 9.1 -> 9.2



Not like this. ypur patches are merged, pls post a fix patch on top.
Thanks!

> Vladimir Sementsov-Ogievskiy (3):
>   qdev-monitor: add option to report GenericError from find_device_state
>   vhost-user-blk: split vhost_user_blk_sync_config()
>   qapi: introduce device-sync-config
> 
>  hw/block/vhost-user-blk.c | 27 ++++++++++++++------
>  hw/virtio/virtio-pci.c    |  9 +++++++
>  include/hw/qdev-core.h    |  6 +++++
>  qapi/qdev.json            | 24 ++++++++++++++++++
>  system/qdev-monitor.c     | 53 ++++++++++++++++++++++++++++++++++++---
>  5 files changed, 108 insertions(+), 11 deletions(-)
> 
> -- 
> 2.34.1

Re: [PATCH v7 0/3] vhost-user-blk: live resize additional APIs

[Vladimir Sementsov-Ogievskiy]

On 06.11.24 21:17, Michael S. Tsirkin wrote:
> On Wed, Nov 06, 2024 at 02:18:34PM +0300, Vladimir Sementsov-Ogievskiy wrote:
>> v7: update QAPI version 9.1 -> 9.2
> 
> 
> 
> Not like this. ypur patches are merged, pls post a fix patch on top.
> Thanks!

Ah, missed this. Ok.

> 
>> Vladimir Sementsov-Ogievskiy (3):
>>    qdev-monitor: add option to report GenericError from find_device_state
>>    vhost-user-blk: split vhost_user_blk_sync_config()
>>    qapi: introduce device-sync-config
>>
>>   hw/block/vhost-user-blk.c | 27 ++++++++++++++------
>>   hw/virtio/virtio-pci.c    |  9 +++++++
>>   include/hw/qdev-core.h    |  6 +++++
>>   qapi/qdev.json            | 24 ++++++++++++++++++
>>   system/qdev-monitor.c     | 53 ++++++++++++++++++++++++++++++++++++---
>>   5 files changed, 108 insertions(+), 11 deletions(-)
>>
>> -- 
>> 2.34.1
> 

-- 
Best regards,
Vladimir