The CONFIG_VFIO switch only works in target specific code. Since
migration/migration.c is common code, the #ifdef does not have
the intended behavior here. Move the related code to a separate
file now which gets compiled via specific_ss instead.

Fixes: 3710586caa ("qapi: Add VFIO devices migration stats in Migration stats")
Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 migration/meson.build |  3 ++-
 migration/migration.c | 15 ---------------
 migration/migration.h |  2 ++
 migration/special.c   | 25 +++++++++++++++++++++++++
 4 files changed, 29 insertions(+), 16 deletions(-)
 create mode 100644 migration/special.c

diff --git a/migration/meson.build b/migration/meson.build
index 9645f44005..e1f72f6ba0 100644
--- a/migration/meson.build
+++ b/migration/meson.build
@@ -30,4 +30,5 @@ softmmu_ss.add(when: ['CONFIG_RDMA', rdma], if_true: files('rdma.c'))
 softmmu_ss.add(when: 'CONFIG_LIVE_BLOCK_MIGRATION', if_true: files('block.c'))
 softmmu_ss.add(when: zstd, if_true: files('multifd-zstd.c'))
 
-specific_ss.add(when: 'CONFIG_SOFTMMU', if_true: files('dirtyrate.c', 'ram.c'))
+specific_ss.add(when: 'CONFIG_SOFTMMU',
+                if_true: files('dirtyrate.c', 'ram.c', 'special.c'))
diff --git a/migration/migration.c b/migration/migration.c
index a5ddf43559..6cc05954c8 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -60,10 +60,6 @@
 #include "qemu/yank.h"
 #include "sysemu/cpus.h"
 
-#ifdef CONFIG_VFIO
-#include "hw/vfio/vfio-common.h"
-#endif
-
 #define MAX_THROTTLE  (128 << 20)      /* Migration transfer speed throttling */
 
 /* Amount of time to allocate to each "chunk" of bandwidth-throttled
@@ -1061,17 +1057,6 @@ static void populate_disk_info(MigrationInfo *info)
     }
 }
 
-static void populate_vfio_info(MigrationInfo *info)
-{
-#ifdef CONFIG_VFIO
-    if (vfio_mig_active()) {
-        info->has_vfio = true;
-        info->vfio = g_malloc0(sizeof(*info->vfio));
-        info->vfio->transferred = vfio_mig_bytes_transferred();
-    }
-#endif
-}
-
 static void fill_source_migration_info(MigrationInfo *info)
 {
     MigrationState *s = migrate_get_current();
diff --git a/migration/migration.h b/migration/migration.h
index db6708326b..2730fa05c0 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -376,4 +376,6 @@ void migration_make_urgent_request(void);
 void migration_consume_urgent_request(void);
 bool migration_rate_limit(void);
 
+void populate_vfio_info(MigrationInfo *info);
+
 #endif
diff --git a/migration/special.c b/migration/special.c
new file mode 100644
index 0000000000..907ebf0a0a
--- /dev/null
+++ b/migration/special.c
@@ -0,0 +1,25 @@
+/*
+ * QEMU live migration - functions that need to be compiled target-specific
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2
+ * or (at your option) any later version.
+ */
+
+#include "qemu/osdep.h"
+#include "qapi/qapi-types-migration.h"
+#include "migration.h"
+
+#ifdef CONFIG_VFIO
+#include "hw/vfio/vfio-common.h"
+#endif
+
+void populate_vfio_info(MigrationInfo *info)
+{
+#ifdef CONFIG_VFIO
+    if (vfio_mig_active()) {
+        info->has_vfio = true;
+        info->vfio = g_malloc0(sizeof(*info->vfio));
+        info->vfio->transferred = vfio_mig_bytes_transferred();
+    }
+#endif
+}
-- 
2.27.0

Hi Thomas,

+Alex

On 3/15/21 8:07 PM, Thomas Huth wrote:
> The CONFIG_VFIO switch only works in target specific code. Since
> migration/migration.c is common code, the #ifdef does not have
> the intended behavior here. Move the related code to a separate
> file now which gets compiled via specific_ss instead.
> 
> Fixes: 3710586caa ("qapi: Add VFIO devices migration stats in Migration stats")
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  migration/meson.build |  3 ++-
>  migration/migration.c | 15 ---------------
>  migration/migration.h |  2 ++
>  migration/special.c   | 25 +++++++++++++++++++++++++
>  4 files changed, 29 insertions(+), 16 deletions(-)
>  create mode 100644 migration/special.c
> 
> diff --git a/migration/meson.build b/migration/meson.build
> index 9645f44005..e1f72f6ba0 100644
> --- a/migration/meson.build
> +++ b/migration/meson.build
> @@ -30,4 +30,5 @@ softmmu_ss.add(when: ['CONFIG_RDMA', rdma], if_true: files('rdma.c'))
>  softmmu_ss.add(when: 'CONFIG_LIVE_BLOCK_MIGRATION', if_true: files('block.c'))
>  softmmu_ss.add(when: zstd, if_true: files('multifd-zstd.c'))
>  
> -specific_ss.add(when: 'CONFIG_SOFTMMU', if_true: files('dirtyrate.c', 'ram.c'))
> +specific_ss.add(when: 'CONFIG_SOFTMMU',
> +                if_true: files('dirtyrate.c', 'ram.c', 'special.c'))

Why not simply name this migration/vfio.c? That way we do not start
mixed bag of everything target specific.

Otherwise LGTM.

On 15/03/2021 22.05, Philippe Mathieu-Daudé wrote:
> Hi Thomas,
> 
> +Alex
> 
> On 3/15/21 8:07 PM, Thomas Huth wrote:
>> The CONFIG_VFIO switch only works in target specific code. Since
>> migration/migration.c is common code, the #ifdef does not have
>> the intended behavior here. Move the related code to a separate
>> file now which gets compiled via specific_ss instead.
>>
>> Fixes: 3710586caa ("qapi: Add VFIO devices migration stats in Migration stats")
>> Signed-off-by: Thomas Huth <thuth@redhat.com>
>> ---
>>   migration/meson.build |  3 ++-
>>   migration/migration.c | 15 ---------------
>>   migration/migration.h |  2 ++
>>   migration/special.c   | 25 +++++++++++++++++++++++++
>>   4 files changed, 29 insertions(+), 16 deletions(-)
>>   create mode 100644 migration/special.c
>>
>> diff --git a/migration/meson.build b/migration/meson.build
>> index 9645f44005..e1f72f6ba0 100644
>> --- a/migration/meson.build
>> +++ b/migration/meson.build
>> @@ -30,4 +30,5 @@ softmmu_ss.add(when: ['CONFIG_RDMA', rdma], if_true: files('rdma.c'))
>>   softmmu_ss.add(when: 'CONFIG_LIVE_BLOCK_MIGRATION', if_true: files('block.c'))
>>   softmmu_ss.add(when: zstd, if_true: files('multifd-zstd.c'))
>>   
>> -specific_ss.add(when: 'CONFIG_SOFTMMU', if_true: files('dirtyrate.c', 'ram.c'))
>> +specific_ss.add(when: 'CONFIG_SOFTMMU',
>> +                if_true: files('dirtyrate.c', 'ram.c', 'special.c'))
> 
> Why not simply name this migration/vfio.c? That way we do not start
> mixed bag of everything target specific.

I don't mind ... well, if we have other small functions there in the future 
that depend on CONFIG switches, a mixed bag file might not be such a bad 
idea instead of having lots and lots of small other files ... OTOH, if there 
is more vfio migration code in the works that might fit here, a name like 
vfio.c would be better, of course. What do the maintainers think?

  Thomas

* Thomas Huth (thuth@redhat.com) wrote:
> On 15/03/2021 22.05, Philippe Mathieu-Daudé wrote:
> > Hi Thomas,
> > 
> > +Alex
> > 
> > On 3/15/21 8:07 PM, Thomas Huth wrote:
> > > The CONFIG_VFIO switch only works in target specific code. Since
> > > migration/migration.c is common code, the #ifdef does not have
> > > the intended behavior here. Move the related code to a separate
> > > file now which gets compiled via specific_ss instead.
> > > 
> > > Fixes: 3710586caa ("qapi: Add VFIO devices migration stats in Migration stats")
> > > Signed-off-by: Thomas Huth <thuth@redhat.com>
> > > ---
> > >   migration/meson.build |  3 ++-
> > >   migration/migration.c | 15 ---------------
> > >   migration/migration.h |  2 ++
> > >   migration/special.c   | 25 +++++++++++++++++++++++++
> > >   4 files changed, 29 insertions(+), 16 deletions(-)
> > >   create mode 100644 migration/special.c
> > > 
> > > diff --git a/migration/meson.build b/migration/meson.build
> > > index 9645f44005..e1f72f6ba0 100644
> > > --- a/migration/meson.build
> > > +++ b/migration/meson.build
> > > @@ -30,4 +30,5 @@ softmmu_ss.add(when: ['CONFIG_RDMA', rdma], if_true: files('rdma.c'))
> > >   softmmu_ss.add(when: 'CONFIG_LIVE_BLOCK_MIGRATION', if_true: files('block.c'))
> > >   softmmu_ss.add(when: zstd, if_true: files('multifd-zstd.c'))
> > > -specific_ss.add(when: 'CONFIG_SOFTMMU', if_true: files('dirtyrate.c', 'ram.c'))
> > > +specific_ss.add(when: 'CONFIG_SOFTMMU',
> > > +                if_true: files('dirtyrate.c', 'ram.c', 'special.c'))
> > 
> > Why not simply name this migration/vfio.c? That way we do not start
> > mixed bag of everything target specific.
> 
> I don't mind ... well, if we have other small functions there in the future
> that depend on CONFIG switches, a mixed bag file might not be such a bad
> idea instead of having lots and lots of small other files ... OTOH, if there
> is more vfio migration code in the works that might fit here, a name like
> vfio.c would be better, of course. What do the maintainers think?

Could this be done with stubs instead of an ifdef; i.e. a stub of
'vfio_mig_active' and 'vfio_mig_bytes_transferred'?

As for naming 'special' is too generic.
'vfio' is too specific (especially since most vfio code ends up under
hw/vfio)

how about migration/target.c  as something which is explicit about why
it's done that way.

Dave

>  Thomas
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK

"Dr. David Alan Gilbert" <dgilbert@redhat.com> wrote:
> * Thomas Huth (thuth@redhat.com) wrote:
>> On 15/03/2021 22.05, Philippe Mathieu-Daudé wrote:
>> > Hi Thomas,
>> > 
>> > +Alex
>> > 
>> > On 3/15/21 8:07 PM, Thomas Huth wrote:
>> > > The CONFIG_VFIO switch only works in target specific code. Since
>> > > migration/migration.c is common code, the #ifdef does not have
>> > > the intended behavior here. Move the related code to a separate
>> > > file now which gets compiled via specific_ss instead.
>> > > 
>> > > Fixes: 3710586caa ("qapi: Add VFIO devices migration stats in
>> > > Migration stats")
>> > > Signed-off-by: Thomas Huth <thuth@redhat.com>
>> > > ---
>> > >   migration/meson.build |  3 ++-
>> > >   migration/migration.c | 15 ---------------
>> > >   migration/migration.h |  2 ++
>> > >   migration/special.c   | 25 +++++++++++++++++++++++++
>> > >   4 files changed, 29 insertions(+), 16 deletions(-)
>> > >   create mode 100644 migration/special.c
>> > > 
>> > > diff --git a/migration/meson.build b/migration/meson.build
>> > > index 9645f44005..e1f72f6ba0 100644
>> > > --- a/migration/meson.build
>> > > +++ b/migration/meson.build
>> > > @@ -30,4 +30,5 @@ softmmu_ss.add(when: ['CONFIG_RDMA', rdma],
>> > > if_true: files('rdma.c'))
>> > >   softmmu_ss.add(when: 'CONFIG_LIVE_BLOCK_MIGRATION', if_true:
>> > > files('block.c'))
>> > >   softmmu_ss.add(when: zstd, if_true: files('multifd-zstd.c'))
>> > > -specific_ss.add(when: 'CONFIG_SOFTMMU', if_true:
>> > > files('dirtyrate.c', 'ram.c'))
>> > > +specific_ss.add(when: 'CONFIG_SOFTMMU',
>> > > +                if_true: files('dirtyrate.c', 'ram.c', 'special.c'))
>> > 
>> > Why not simply name this migration/vfio.c? That way we do not start
>> > mixed bag of everything target specific.
>> 
>> I don't mind ... well, if we have other small functions there in the future
>> that depend on CONFIG switches, a mixed bag file might not be such a bad
>> idea instead of having lots and lots of small other files ... OTOH, if there
>> is more vfio migration code in the works that might fit here, a name like
>> vfio.c would be better, of course. What do the maintainers think?
>
> Could this be done with stubs instead of an ifdef; i.e. a stub of
> 'vfio_mig_active' and 'vfio_mig_bytes_transferred'?

My understanding is that they can't (at least easily).
Because they are really target specific :-(

> As for naming 'special' is too generic.
> 'vfio' is too specific (especially since most vfio code ends up under
> hw/vfio)
>
> how about migration/target.c  as something which is explicit about why
> it's done that way.

I agree with the target name.

But I can't think of a really much easier way that what is in this
patch.

To make stubs you need to ifdef half of hw/vfio/vfio-common.h, or just
put the #ifdef in migration/target.c

Even althought I hate #ifdefs, I am not sure that the stubs options is
much clearly here.

Later, Juan.