[Qemu-devel] [PATCH v2 0/5] Disable hotplug during migration

[Qemu-devel] [PATCH v2 0/5] Disable hotplug during migration

[Juan Quintela]

Hi

This updates patches with all the comments received.
I move qdev_unplug() to make linux-user compile.

Please, review.


[RFC - v1]
This series disable hotplug/unplug during migration.  Thank to Markus
for explaining where I had to put the checks.  Why?  Because during
migration we will fail if there are changes.  For instance, in
postcopy, if we add a memory region, we would failing.  Same for other
devices if they are not setup exactly the same on destination.

Iidea would be to disable it, andthen enable for the thing that we know that work.

This series are on top of my previous RAMState v2 serie.

Commets, please?

Thanks, Juan.


*** BLURB HERE ***

Juan Quintela (5):
  qdev: qdev_hotplug is really a bool
  qdev: Export qdev_hot_removed
  qdev: Move qdev_unplug() to qdev-monitor.c
  migration: Disable hotplug/unplug during migration
  ram: Remove migration_bitmap_extend()

 exec.c                  |  1 -
 hw/core/qdev.c          | 40 +++-------------------------------------
 include/exec/ram_addr.h |  2 --
 include/hw/qdev-core.h  |  3 ++-
 migration/ram.c         | 34 ----------------------------------
 qdev-monitor.c          | 45 +++++++++++++++++++++++++++++++++++++++++++++
 6 files changed, 50 insertions(+), 75 deletions(-)

-- 
2.9.3

[Qemu-devel] [PATCH 1/5] qdev: qdev_hotplug is really a bool

[Juan Quintela]

Signed-off-by: Juan Quintela <quintela@redhat.com>
---
 hw/core/qdev.c         | 4 ++--
 include/hw/qdev-core.h | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/hw/core/qdev.c b/hw/core/qdev.c
index 1e7fb33..6fa46b5 100644
--- a/hw/core/qdev.c
+++ b/hw/core/qdev.c
@@ -39,7 +39,7 @@
 #include "qapi-event.h"
 #include "migration/migration.h"
 
-int qdev_hotplug = 0;
+bool qdev_hotplug = false;
 static bool qdev_hot_added = false;
 static bool qdev_hot_removed = false;
 
@@ -385,7 +385,7 @@ void qdev_machine_creation_done(void)
      * ok, initial machine setup is done, starting from now we can
      * only create hotpluggable devices
      */
-    qdev_hotplug = 1;
+    qdev_hotplug = true;
 }
 
 bool qdev_machine_modified(void)
diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
index b44b476..a96a913 100644
--- a/include/hw/qdev-core.h
+++ b/include/hw/qdev-core.h
@@ -386,7 +386,7 @@ Object *qdev_get_machine(void);
 /* FIXME: make this a link<> */
 void qdev_set_parent_bus(DeviceState *dev, BusState *bus);
 
-extern int qdev_hotplug;
+extern bool qdev_hotplug;
 
 char *qdev_get_dev_path(DeviceState *dev);
 
-- 
2.9.3

Re: [Qemu-devel] [PATCH 1/5] qdev: qdev_hotplug is really a bool

[Eric Blake]

[-- Attachment #1: Type: text/plain, Size: 388 bytes --]

On 04/06/2017 08:13 AM, Juan Quintela wrote:
> Signed-off-by: Juan Quintela <quintela@redhat.com>
> ---
>  hw/core/qdev.c         | 4 ++--
>  include/hw/qdev-core.h | 2 +-
>  2 files changed, 3 insertions(+), 3 deletions(-)

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH 1/5] qdev: qdev_hotplug is really a bool

[Philippe Mathieu-Daudé]

On 04/06/2017 10:13 AM, Juan Quintela wrote:
> Signed-off-by: Juan Quintela <quintela@redhat.com>

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

> ---
>  hw/core/qdev.c         | 4 ++--
>  include/hw/qdev-core.h | 2 +-
>  2 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/hw/core/qdev.c b/hw/core/qdev.c
> index 1e7fb33..6fa46b5 100644
> --- a/hw/core/qdev.c
> +++ b/hw/core/qdev.c
> @@ -39,7 +39,7 @@
>  #include "qapi-event.h"
>  #include "migration/migration.h"
>
> -int qdev_hotplug = 0;
> +bool qdev_hotplug = false;
>  static bool qdev_hot_added = false;
>  static bool qdev_hot_removed = false;
>
> @@ -385,7 +385,7 @@ void qdev_machine_creation_done(void)
>       * ok, initial machine setup is done, starting from now we can
>       * only create hotpluggable devices
>       */
> -    qdev_hotplug = 1;
> +    qdev_hotplug = true;
>  }
>
>  bool qdev_machine_modified(void)
> diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
> index b44b476..a96a913 100644
> --- a/include/hw/qdev-core.h
> +++ b/include/hw/qdev-core.h
> @@ -386,7 +386,7 @@ Object *qdev_get_machine(void);
>  /* FIXME: make this a link<> */
>  void qdev_set_parent_bus(DeviceState *dev, BusState *bus);
>
> -extern int qdev_hotplug;
> +extern bool qdev_hotplug;
>
>  char *qdev_get_dev_path(DeviceState *dev);
>
>

[Qemu-devel] [PATCH 2/5] qdev: Export qdev_hot_removed

[Juan Quintela]

I need to move qdev_unplug to qdev-monitor in the following patch, and
it needs access to this variable.

Signed-off-by: Juan Quintela <quintela@redhat.com>
---
 hw/core/qdev.c         | 2 +-
 include/hw/qdev-core.h | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/hw/core/qdev.c b/hw/core/qdev.c
index 6fa46b5..c26cf84 100644
--- a/hw/core/qdev.c
+++ b/hw/core/qdev.c
@@ -41,7 +41,7 @@
 
 bool qdev_hotplug = false;
 static bool qdev_hot_added = false;
-static bool qdev_hot_removed = false;
+bool qdev_hot_removed = false;
 
 const VMStateDescription *qdev_get_vmsd(DeviceState *dev)
 {
diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
index a96a913..f09b6b7 100644
--- a/include/hw/qdev-core.h
+++ b/include/hw/qdev-core.h
@@ -387,6 +387,7 @@ Object *qdev_get_machine(void);
 void qdev_set_parent_bus(DeviceState *dev, BusState *bus);
 
 extern bool qdev_hotplug;
+extern bool qdev_hot_removed;
 
 char *qdev_get_dev_path(DeviceState *dev);
 
-- 
2.9.3

Re: [Qemu-devel] [PATCH 2/5] qdev: Export qdev_hot_removed

[Eric Blake]

[-- Attachment #1: Type: text/plain, Size: 503 bytes --]

On 04/06/2017 08:13 AM, Juan Quintela wrote:
> I need to move qdev_unplug to qdev-monitor in the following patch, and
> it needs access to this variable.
> 
> Signed-off-by: Juan Quintela <quintela@redhat.com>
> ---
>  hw/core/qdev.c         | 2 +-
>  include/hw/qdev-core.h | 1 +
>  2 files changed, 2 insertions(+), 1 deletion(-)
> 

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH 2/5] qdev: Export qdev_hot_removed

[Markus Armbruster]

Cc: Paolo for additional qdev expertise.

Juan Quintela <quintela@redhat.com> writes:

> I need to move qdev_unplug to qdev-monitor in the following patch, and
> it needs access to this variable.
>
> Signed-off-by: Juan Quintela <quintela@redhat.com>
> ---
>  hw/core/qdev.c         | 2 +-
>  include/hw/qdev-core.h | 1 +
>  2 files changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/hw/core/qdev.c b/hw/core/qdev.c
> index 6fa46b5..c26cf84 100644
> --- a/hw/core/qdev.c
> +++ b/hw/core/qdev.c
> @@ -41,7 +41,7 @@
>  
>  bool qdev_hotplug = false;
>  static bool qdev_hot_added = false;
> -static bool qdev_hot_removed = false;
> +bool qdev_hot_removed = false;

Makes qdev_hot_added and qdev_hot_removed differently static, which is
weird.

The reason for this asymmetry is the asymmetry in how they get set:

* qdev_hot_added gets set .instance_init() method in device_initfn()
  when it runs after qdev_machine_creation_done().  It's called by
  qdev_device_add() via object_new()... then.

* qdev_hot_removed gets set directly in qdev_unplug(), not in the
  .instance_finalize() method device_finalize().

  Note that for some devices, qdev_unplug() only requests unplug.
  Actual unplug happens later, or even not at all.  device_finalize()
  runs on actual unplug.

Questions:

* Is setting qdev_hot_removed on unplug *requests* correct?  Or should
  it be set only on *actual* unplug?

* Can we avoid the asymmetry?  It's a bit ugly.

>  const VMStateDescription *qdev_get_vmsd(DeviceState *dev)
>  {
> diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
> index a96a913..f09b6b7 100644
> --- a/include/hw/qdev-core.h
> +++ b/include/hw/qdev-core.h
> @@ -387,6 +387,7 @@ Object *qdev_get_machine(void);
>  void qdev_set_parent_bus(DeviceState *dev, BusState *bus);
>  
>  extern bool qdev_hotplug;
> +extern bool qdev_hot_removed;
>  
>  char *qdev_get_dev_path(DeviceState *dev);

[Qemu-devel] [PATCH 3/5] qdev: Move qdev_unplug() to qdev-monitor.c

[Juan Quintela]

It is not used by linux-user, otherwise I need to to create one stub
for migration_is_idle() on following patch.

Signed-off-by: Juan Quintela <quintela@redhat.com>
---
 hw/core/qdev.c | 34 ----------------------------------
 qdev-monitor.c | 34 ++++++++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+), 34 deletions(-)

diff --git a/hw/core/qdev.c b/hw/core/qdev.c
index c26cf84..0df0050 100644
--- a/hw/core/qdev.c
+++ b/hw/core/qdev.c
@@ -271,40 +271,6 @@ HotplugHandler *qdev_get_hotplug_handler(DeviceState *dev)
     return hotplug_ctrl;
 }
 
-void qdev_unplug(DeviceState *dev, Error **errp)
-{
-    DeviceClass *dc = DEVICE_GET_CLASS(dev);
-    HotplugHandler *hotplug_ctrl;
-    HotplugHandlerClass *hdc;
-
-    if (dev->parent_bus && !qbus_is_hotpluggable(dev->parent_bus)) {
-        error_setg(errp, QERR_BUS_NO_HOTPLUG, dev->parent_bus->name);
-        return;
-    }
-
-    if (!dc->hotpluggable) {
-        error_setg(errp, QERR_DEVICE_NO_HOTPLUG,
-                   object_get_typename(OBJECT(dev)));
-        return;
-    }
-
-    qdev_hot_removed = true;
-
-    hotplug_ctrl = qdev_get_hotplug_handler(dev);
-    /* hotpluggable device MUST have HotplugHandler, if it doesn't
-     * then something is very wrong with it */
-    g_assert(hotplug_ctrl);
-
-    /* If device supports async unplug just request it to be done,
-     * otherwise just remove it synchronously */
-    hdc = HOTPLUG_HANDLER_GET_CLASS(hotplug_ctrl);
-    if (hdc->unplug_request) {
-        hotplug_handler_unplug_request(hotplug_ctrl, dev, errp);
-    } else {
-        hotplug_handler_unplug(hotplug_ctrl, dev, errp);
-    }
-}
-
 static int qdev_reset_one(DeviceState *dev, void *opaque)
 {
     device_reset(dev);
diff --git a/qdev-monitor.c b/qdev-monitor.c
index 5f2fcdf..bb3d8ba 100644
--- a/qdev-monitor.c
+++ b/qdev-monitor.c
@@ -836,6 +836,40 @@ static DeviceState *find_device_state(const char *id, Error **errp)
     return DEVICE(obj);
 }
 
+void qdev_unplug(DeviceState *dev, Error **errp)
+{
+    DeviceClass *dc = DEVICE_GET_CLASS(dev);
+    HotplugHandler *hotplug_ctrl;
+    HotplugHandlerClass *hdc;
+
+    if (dev->parent_bus && !qbus_is_hotpluggable(dev->parent_bus)) {
+        error_setg(errp, QERR_BUS_NO_HOTPLUG, dev->parent_bus->name);
+        return;
+    }
+
+    if (!dc->hotpluggable) {
+        error_setg(errp, QERR_DEVICE_NO_HOTPLUG,
+                   object_get_typename(OBJECT(dev)));
+        return;
+    }
+
+    qdev_hot_removed = true;
+
+    hotplug_ctrl = qdev_get_hotplug_handler(dev);
+    /* hotpluggable device MUST have HotplugHandler, if it doesn't
+     * then something is very wrong with it */
+    g_assert(hotplug_ctrl);
+
+    /* If device supports async unplug just request it to be done,
+     * otherwise just remove it synchronously */
+    hdc = HOTPLUG_HANDLER_GET_CLASS(hotplug_ctrl);
+    if (hdc->unplug_request) {
+        hotplug_handler_unplug_request(hotplug_ctrl, dev, errp);
+    } else {
+        hotplug_handler_unplug(hotplug_ctrl, dev, errp);
+    }
+}
+
 void qmp_device_del(const char *id, Error **errp)
 {
     DeviceState *dev = find_device_state(id, errp);
-- 
2.9.3

Re: [Qemu-devel] [PATCH 3/5] qdev: Move qdev_unplug() to qdev-monitor.c

[Eric Blake]

[-- Attachment #1: Type: text/plain, Size: 561 bytes --]

On 04/06/2017 08:13 AM, Juan Quintela wrote:
> It is not used by linux-user, otherwise I need to to create one stub
> for migration_is_idle() on following patch.
> 
> Signed-off-by: Juan Quintela <quintela@redhat.com>
> ---
>  hw/core/qdev.c | 34 ----------------------------------
>  qdev-monitor.c | 34 ++++++++++++++++++++++++++++++++++
>  2 files changed, 34 insertions(+), 34 deletions(-)

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH 3/5] qdev: Move qdev_unplug() to qdev-monitor.c

[Markus Armbruster]

Juan Quintela <quintela@redhat.com> writes:

> It is not used by linux-user, otherwise I need to to create one stub
> for migration_is_idle() on following patch.
>
> Signed-off-by: Juan Quintela <quintela@redhat.com>
> ---
>  hw/core/qdev.c | 34 ----------------------------------
>  qdev-monitor.c | 34 ++++++++++++++++++++++++++++++++++
>  2 files changed, 34 insertions(+), 34 deletions(-)

Makes sense because its buddy qdev_device_add() is already in
qdev-monitor.c.

Reviewed-by: Markus Armbruster <armbru@redhat.com>

[Qemu-devel] [PATCH 4/5] migration: Disable hotplug/unplug during migration

[Juan Quintela]

Until we have reviewed what can/can't be hotplug during migration,
disable it.  We can enable it later for the things that we know that
work.  For instance, memory hotplug during postcopy don't work
currently.

Signed-off-by: Juan Quintela <quintela@redhat.com>

--

- Fix typo.  Thanks Thomas.
- Delay migration check after we have checked that we can hotplug that
  device.

Signed-off-by: Juan Quintela <quintela@redhat.com>
---
 qdev-monitor.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/qdev-monitor.c b/qdev-monitor.c
index bb3d8ba..752c362 100644
--- a/qdev-monitor.c
+++ b/qdev-monitor.c
@@ -29,6 +29,7 @@
 #include "qemu/error-report.h"
 #include "qemu/help_option.h"
 #include "sysemu/block-backend.h"
+#include "migration/migration.h"
 
 /*
  * Aliases were a bad idea from the start.  Let's keep them
@@ -603,6 +604,11 @@ DeviceState *qdev_device_add(QemuOpts *opts, Error **errp)
         return NULL;
     }
 
+    if (!migration_is_idle()) {
+        error_setg(errp, "device_add not allowed while migrating");
+        return NULL;
+    }
+
     /* create device */
     dev = DEVICE(object_new(driver));
 
@@ -853,6 +859,11 @@ void qdev_unplug(DeviceState *dev, Error **errp)
         return;
     }
 
+    if (!migration_is_idle()) {
+        error_setg(errp, "device_add not allowed while migrating");
+        return;
+    }
+
     qdev_hot_removed = true;
 
     hotplug_ctrl = qdev_get_hotplug_handler(dev);
-- 
2.9.3

Re: [Qemu-devel] [PATCH 4/5] migration: Disable hotplug/unplug during migration

[Eric Blake]

[-- Attachment #1: Type: text/plain, Size: 1227 bytes --]

On 04/06/2017 08:13 AM, Juan Quintela wrote:
> Until we have reviewed what can/can't be hotplug during migration,

s/hotplug/hotplugged/

> disable it.  We can enable it later for the things that we know that
> work.  For instance, memory hotplug during postcopy don't work

s/don't/doesn't/

> currently.
> 
> Signed-off-by: Juan Quintela <quintela@redhat.com>
> 
> --
> 

> @@ -603,6 +604,11 @@ DeviceState *qdev_device_add(QemuOpts *opts, Error **errp)
>          return NULL;
>      }
>  
> +    if (!migration_is_idle()) {
> +        error_setg(errp, "device_add not allowed while migrating");
> +        return NULL;
> +    }
> +
>      /* create device */
>      dev = DEVICE(object_new(driver));
>  
> @@ -853,6 +859,11 @@ void qdev_unplug(DeviceState *dev, Error **errp)
>          return;
>      }
>  
> +    if (!migration_is_idle()) {
> +        error_setg(errp, "device_add not allowed while migrating");

s/device_add/device_del/ ?

> +        return;
> +    }
> +
>      qdev_hot_removed = true;
>  
>      hotplug_ctrl = qdev_get_hotplug_handler(dev);
> 

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH 4/5] migration: Disable hotplug/unplug during migration

[Juan Quintela]

Eric Blake <eblake@redhat.com> wrote:
> On 04/06/2017 08:13 AM, Juan Quintela wrote:
>> Until we have reviewed what can/can't be hotplug during migration,
>
> s/hotplug/hotplugged/
>
>> disable it.  We can enable it later for the things that we know that
>> work.  For instance, memory hotplug during postcopy don't work
>
> s/don't/doesn't/

Fixed the three typos, thanks.

[Qemu-devel] [PATCH 5/5] ram: Remove migration_bitmap_extend()

[Juan Quintela]

We have disabled memory hotplug, so we don't need to handle
migration_bitamp there.

Signed-off-by: Juan Quintela <quintela@redhat.com>
---
 exec.c                  |  1 -
 include/exec/ram_addr.h |  2 --
 migration/ram.c         | 34 ----------------------------------
 3 files changed, 37 deletions(-)

diff --git a/exec.c b/exec.c
index de843f4..c2def9e 100644
--- a/exec.c
+++ b/exec.c
@@ -1758,7 +1758,6 @@ static void ram_block_add(RAMBlock *new_block, Error **errp)
     new_ram_size = MAX(old_ram_size,
               (new_block->offset + new_block->max_length) >> TARGET_PAGE_BITS);
     if (new_ram_size > old_ram_size) {
-        migration_bitmap_extend(old_ram_size, new_ram_size);
         dirty_memory_extend(old_ram_size, new_ram_size);
     }
     /* Keep the list sorted from biggest to smallest block.  Unlike QTAILQ,
diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h
index a8411c7..c9ddcd0 100644
--- a/include/exec/ram_addr.h
+++ b/include/exec/ram_addr.h
@@ -413,7 +413,5 @@ uint64_t cpu_physical_memory_sync_dirty_bitmap(unsigned long *dest,
 
     return num_dirty;
 }
-
-void migration_bitmap_extend(ram_addr_t old, ram_addr_t new);
 #endif
 #endif
diff --git a/migration/ram.c b/migration/ram.c
index 92d6ff7..f05080f 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -1496,40 +1496,6 @@ static void ram_state_reset(RAMState *rs)
 
 #define MAX_WAIT 50 /* ms, half buffered_file limit */
 
-void migration_bitmap_extend(ram_addr_t old, ram_addr_t new)
-{
-    RAMState *rs = &ram_state;
-
-    /* called in qemu main thread, so there is
-     * no writing race against this migration_bitmap
-     */
-    if (rs->ram_bitmap) {
-        RAMBitmap *old_bitmap = rs->ram_bitmap, *bitmap;
-        bitmap = g_new(RAMBitmap, 1);
-        bitmap->bmap = bitmap_new(new);
-
-        /* prevent migration_bitmap content from being set bit
-         * by migration_bitmap_sync_range() at the same time.
-         * it is safe to migration if migration_bitmap is cleared bit
-         * at the same time.
-         */
-        qemu_mutex_lock(&rs->bitmap_mutex);
-        bitmap_copy(bitmap->bmap, old_bitmap->bmap, old);
-        bitmap_set(bitmap->bmap, old, new - old);
-
-        /* We don't have a way to safely extend the sentmap
-         * with RCU; so mark it as missing, entry to postcopy
-         * will fail.
-         */
-        bitmap->unsentmap = NULL;
-
-        atomic_rcu_set(&rs->ram_bitmap, bitmap);
-        qemu_mutex_unlock(&rs->bitmap_mutex);
-        rs->migration_dirty_pages += new - old;
-        call_rcu(old_bitmap, migration_bitmap_free, rcu);
-    }
-}
-
 /*
  * 'expected' is the value you expect the bitmap mostly to be full
  * of; it won't bother printing lines that are all this value.
-- 
2.9.3

Re: [Qemu-devel] [PATCH 5/5] ram: Remove migration_bitmap_extend()

[Eric Blake]

[-- Attachment #1: Type: text/plain, Size: 535 bytes --]

On 04/06/2017 08:13 AM, Juan Quintela wrote:
> We have disabled memory hotplug, so we don't need to handle
> migration_bitamp there.
> 
> Signed-off-by: Juan Quintela <quintela@redhat.com>
> ---
>  exec.c                  |  1 -
>  include/exec/ram_addr.h |  2 --
>  migration/ram.c         | 34 ----------------------------------
>  3 files changed, 37 deletions(-)

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH v2 0/5] Disable hotplug during migration

[Hailiang Zhang]

On 2017/4/6 21:13, Juan Quintela wrote:
> Hi
>
> This updates patches with all the comments received.
> I move qdev_unplug() to make linux-user compile.
>
> Please, review.
>
>
> [RFC - v1]
> This series disable hotplug/unplug during migration.  Thank to Markus
> for explaining where I had to put the checks.  Why?  Because during
> migration we will fail if there are changes.  For instance, in
> postcopy, if we add a memory region, we would failing.  Same for other
> devices if they are not setup exactly the same on destination.
>
> Iidea would be to disable it, andthen enable for the thing that we know that work.
>
> This series are on top of my previous RAMState v2 serie.
>
> Commets, please?

Make sense, this will benefit COLO too :)

After the types found by Eric be fixed in patch 5,
Reviewed-by: zhanghailiang <zhang.zhanghailiang@huawei.com>

> Thanks, Juan.
>
>
> *** BLURB HERE ***
>
> Juan Quintela (5):
>    qdev: qdev_hotplug is really a bool
>    qdev: Export qdev_hot_removed
>    qdev: Move qdev_unplug() to qdev-monitor.c
>    migration: Disable hotplug/unplug during migration
>    ram: Remove migration_bitmap_extend()
>
>   exec.c                  |  1 -
>   hw/core/qdev.c          | 40 +++-------------------------------------
>   include/exec/ram_addr.h |  2 --
>   include/hw/qdev-core.h  |  3 ++-
>   migration/ram.c         | 34 ----------------------------------
>   qdev-monitor.c          | 45 +++++++++++++++++++++++++++++++++++++++++++++
>   6 files changed, 50 insertions(+), 75 deletions(-)
>