Re: [Qemu-devel] [PATCH v9 13/20] Add mandatory_features to vhost_dev

[Michael S. Tsirkin]

On Tue, Mar 04, 2014 at 07:22:56PM +0100, Antonios Motakis wrote:
> This will be used in a following patch to ensure that a vhost-user
> client reconnecting to QEMU supports the features that were exposed
> by the first client that initiated the virtio-net session.
> 
> Signed-off-by: Antonios Motakis <address@hidden>
> Signed-off-by: Nikolay Nikolaev <address@hidden>

Why isn't checking features, or backend_features field sufficient?


> ---
>  hw/net/vhost_net.c        | 10 ++++++++++
>  include/hw/virtio/vhost.h |  1 +
>  include/net/vhost_net.h   |  2 ++
>  3 files changed, 13 insertions(+)
> 
> diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
> index 0fb4fa5..38e1e8a 100644
> --- a/hw/net/vhost_net.c
> +++ b/hw/net/vhost_net.c
> @@ -80,6 +80,11 @@ void vhost_net_ack_features(struct vhost_net *net, 
> unsigned features)
>      }
>  }
>  
> +unsigned long long vhost_net_features(VHostNetState *net)
> +{
> +    return net->dev.features;
> +}
> +
>  static int vhost_net_get_fd(NetClientState *backend)
>  {
>      switch (backend->info->type) {
> @@ -112,6 +117,7 @@ struct vhost_net *vhost_net_init(VhostNetOptions *options)
>  
>      net->dev.nvqs = 2;
>      net->dev.vqs = net->vqs;
> +    net->dev.mandatory_features = options->mandatory_features;
>  
>      r = vhost_dev_init(&net->dev, options->opaque,
>                         options->force);
> @@ -347,6 +353,10 @@ unsigned vhost_net_get_features(struct vhost_net *net, 
> unsigned features)
>  void vhost_net_ack_features(struct vhost_net *net, unsigned features)
>  {
>  }
> +unsigned long long vhost_net_features(struct vhost_net *net)
> +{
> +    return 0;
> +}
>  
>  bool vhost_net_virtqueue_pending(VHostNetState *net, int idx)
>  {
> diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
> index 97641b6..0068d40 100644
> --- a/include/hw/virtio/vhost.h
> +++ b/include/hw/virtio/vhost.h
> @@ -41,6 +41,7 @@ struct vhost_dev {
>      unsigned long long features;
>      unsigned long long acked_features;
>      unsigned long long backend_features;
> +    unsigned long long mandatory_features;
>      bool started;
>      bool log_enabled;
>      vhost_log_chunk_t *log;
> diff --git a/include/net/vhost_net.h b/include/net/vhost_net.h
> index 2067ee2..b39bb45 100644
> --- a/include/net/vhost_net.h
> +++ b/include/net/vhost_net.h
> @@ -10,6 +10,7 @@ typedef struct VhostNetOptions {
>      NetClientState *net_backend;
>      void *opaque;
>      bool force;
> +    unsigned long long mandatory_features;
>  } VhostNetOptions;
>  
>  struct vhost_net *vhost_net_init(VhostNetOptions *options);
> @@ -22,6 +23,7 @@ void vhost_net_cleanup(VHostNetState *net);
>  
>  unsigned vhost_net_get_features(VHostNetState *net, unsigned features);
>  void vhost_net_ack_features(VHostNetState *net, unsigned features);
> +unsigned long long vhost_net_features(VHostNetState *net);
>  
>  bool vhost_net_virtqueue_pending(VHostNetState *net, int n);
>  void vhost_net_virtqueue_mask(VHostNetState *net, VirtIODevice *dev,
> -- 
> 1.8.3.2