From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

Add a 2nd 'vhost_memory' structure that will be used to build
the new version as the listener iterates over the address space.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 hw/virtio/vhost.c         | 3 +++
 include/hw/virtio/vhost.h | 1 +
 2 files changed, 4 insertions(+)

diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index c7ce7baf9b..4523f45587 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -632,6 +632,8 @@ static void vhost_begin(MemoryListener *listener)
                                          memory_listener);
     dev->mem_changed_end_addr = 0;
     dev->mem_changed_start_addr = -1;
+
+    dev->tmp_mem = g_malloc0(offsetof(struct vhost_memory, regions));
 }
 
 static void vhost_commit(MemoryListener *listener)
@@ -641,6 +643,7 @@ static void vhost_commit(MemoryListener *listener)
     uint64_t log_size;
     int r;
 
+    g_free(dev->tmp_mem);
     if (!dev->memory_changed) {
         return;
     }
diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
index 467dc7794b..41f9e569be 100644
--- a/include/hw/virtio/vhost.h
+++ b/include/hw/virtio/vhost.h
@@ -70,6 +70,7 @@ struct vhost_dev {
     bool memory_changed;
     hwaddr mem_changed_start_addr;
     hwaddr mem_changed_end_addr;
+    struct vhost_memory *tmp_mem;
     const VhostOps *vhost_ops;
     void *opaque;
     struct vhost_log *log;
-- 
2.14.3

On Wed, 13 Dec 2017 18:08:04 +0000
"Dr. David Alan Gilbert (git)" <dgilbert@redhat.com> wrote:

> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> 
> Add a 2nd 'vhost_memory' structure that will be used to build
> the new version as the listener iterates over the address space.
I'd suggest to add temporary 'mem_sections' instead and
create/use/free temporary 'vhost_memory' structure at commit time,
(1 less duplicated data set to keep in memory)

> 
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> ---
>  hw/virtio/vhost.c         | 3 +++
>  include/hw/virtio/vhost.h | 1 +
>  2 files changed, 4 insertions(+)
> 
> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> index c7ce7baf9b..4523f45587 100644
> --- a/hw/virtio/vhost.c
> +++ b/hw/virtio/vhost.c
> @@ -632,6 +632,8 @@ static void vhost_begin(MemoryListener *listener)
>                                           memory_listener);
>      dev->mem_changed_end_addr = 0;
>      dev->mem_changed_start_addr = -1;
> +
> +    dev->tmp_mem = g_malloc0(offsetof(struct vhost_memory, regions));
>  }
>  
>  static void vhost_commit(MemoryListener *listener)
> @@ -641,6 +643,7 @@ static void vhost_commit(MemoryListener *listener)
>      uint64_t log_size;
>      int r;
>  
> +    g_free(dev->tmp_mem);
>      if (!dev->memory_changed) {
>          return;
>      }
> diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
> index 467dc7794b..41f9e569be 100644
> --- a/include/hw/virtio/vhost.h
> +++ b/include/hw/virtio/vhost.h
> @@ -70,6 +70,7 @@ struct vhost_dev {
>      bool memory_changed;
>      hwaddr mem_changed_start_addr;
>      hwaddr mem_changed_end_addr;
> +    struct vhost_memory *tmp_mem;
>      const VhostOps *vhost_ops;
>      void *opaque;
>      struct vhost_log *log;

* Igor Mammedov (imammedo@redhat.com) wrote:
> On Wed, 13 Dec 2017 18:08:04 +0000
> "Dr. David Alan Gilbert (git)" <dgilbert@redhat.com> wrote:
> 
> > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> > 
> > Add a 2nd 'vhost_memory' structure that will be used to build
> > the new version as the listener iterates over the address space.
> I'd suggest to add temporary 'mem_sections' instead and
> create/use/free temporary 'vhost_memory' structure at commit time,
> (1 less duplicated data set to keep in memory)

I don't see how this leads to less duplication;  I still end up with
one set of temporary structures, and the sections use Int128 which
is a pain to work with in the comparison/merging code.

Dave

> > 
> > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> > ---
> >  hw/virtio/vhost.c         | 3 +++
> >  include/hw/virtio/vhost.h | 1 +
> >  2 files changed, 4 insertions(+)
> > 
> > diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> > index c7ce7baf9b..4523f45587 100644
> > --- a/hw/virtio/vhost.c
> > +++ b/hw/virtio/vhost.c
> > @@ -632,6 +632,8 @@ static void vhost_begin(MemoryListener *listener)
> >                                           memory_listener);
> >      dev->mem_changed_end_addr = 0;
> >      dev->mem_changed_start_addr = -1;
> > +
> > +    dev->tmp_mem = g_malloc0(offsetof(struct vhost_memory, regions));
> >  }
> >  
> >  static void vhost_commit(MemoryListener *listener)
> > @@ -641,6 +643,7 @@ static void vhost_commit(MemoryListener *listener)
> >      uint64_t log_size;
> >      int r;
> >  
> > +    g_free(dev->tmp_mem);
> >      if (!dev->memory_changed) {
> >          return;
> >      }
> > diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
> > index 467dc7794b..41f9e569be 100644
> > --- a/include/hw/virtio/vhost.h
> > +++ b/include/hw/virtio/vhost.h
> > @@ -70,6 +70,7 @@ struct vhost_dev {
> >      bool memory_changed;
> >      hwaddr mem_changed_start_addr;
> >      hwaddr mem_changed_end_addr;
> > +    struct vhost_memory *tmp_mem;
> >      const VhostOps *vhost_ops;
> >      void *opaque;
> >      struct vhost_log *log;
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK