[PATCH v2 01/15] net: Introduce NetClientInfo.check_peer_type()

[Damien Hedde]

On 10/8/21 15:34, Kevin Wolf wrote:
> Some network backends (vhost-user and vhost-vdpa) work only with
> specific devices. At startup, they second guess what the command line
> option handling will do and error out if they think a non-virtio device
> will attach to them.
> 
> This second guessing is not only ugly, it can lead to wrong error
> messages ('-device floppy,netdev=foo' should complain about an unknown
> property, not about the wrong kind of network device being attached) and
> completely ignores hotplugging.
> 
> Add a callback where backends can check compatibility with a device when
> it actually tries to attach, even on hotplug.
> 
> Signed-off-by: Kevin Wolf <kwolf at redhat.com>

Reviewed-by: Damien Hedde <damien.hedde at greensocs.com>
> ---
>   include/net/net.h                | 2 ++
>   hw/core/qdev-properties-system.c | 6 ++++++
>   2 files changed, 8 insertions(+)
> 
> diff --git a/include/net/net.h b/include/net/net.h
> index 5d1508081f..986288eb07 100644
> --- a/include/net/net.h
> +++ b/include/net/net.h
> @@ -62,6 +62,7 @@ typedef struct SocketReadState SocketReadState;
>   typedef void (SocketReadStateFinalize)(SocketReadState *rs);
>   typedef void (NetAnnounce)(NetClientState *);
>   typedef bool (SetSteeringEBPF)(NetClientState *, int);
> +typedef bool (NetCheckPeerType)(NetClientState *, ObjectClass *, Error **);
>   
>   typedef struct NetClientInfo {
>       NetClientDriver type;
> @@ -84,6 +85,7 @@ typedef struct NetClientInfo {
>       SetVnetBE *set_vnet_be;
>       NetAnnounce *announce;
>       SetSteeringEBPF *set_steering_ebpf;
> +    NetCheckPeerType *check_peer_type;
>   } NetClientInfo;
>   
>   struct NetClientState {
> diff --git a/hw/core/qdev-properties-system.c b/hw/core/qdev-properties-system.c
> index e71f5d64d1..a91f60567a 100644
> --- a/hw/core/qdev-properties-system.c
> +++ b/hw/core/qdev-properties-system.c
> @@ -431,6 +431,12 @@ static void set_netdev(Object *obj, Visitor *v, const char *name,
>               goto out;
>           }
>   
> +        if (peers[i]->info->check_peer_type) {
> +            if (!peers[i]->info->check_peer_type(peers[i], obj->class, errp)) {
> +                goto out;
> +            }
> +        }
> +
>           ncs[i] = peers[i];
>           ncs[i]->queue_index = i;
>       }
>