Re: [Qemu-devel] [PATCH v4 3/6] vhost: Add temporary memory structure

[Igor Mammedov <imammedo@redhat.com>]

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;