net: Add get_vhost_net callback to NetClientInfo

The get_vhost_net() function previously contained a large switch
statement to find the VHostNetState pointer based on the net
client's type. This created a tight coupling, requiring the generic
vhost layer to be aware of every specific backend that supported
vhost, such as tap, vhost-user, and vhost-vdpa.

This approach is not scalable and requires modifying a central function
for any new backend. It also forced each backend to expose its internal
getter function in a public header file.

This patch refactors the logic by introducing a new get_vhost_net
function pointer to the NetClientInfo struct. The central
get_vhost_net() function is now a simple, generic dispatcher that
invokes the callback provided by the net client.

Each backend now implements its own private getter and registers it in
its NetClientInfo.

Signed-off-by: Laurent Vivier <lvivier@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
index 58d738945d..0b86c917ed 100644
--- a/net/vhost-vdpa.c
+++ b/net/vhost-vdpa.c
@@ -132,7 +132,7 @@ static const uint64_t vdpa_svq_device_features =
 
 #define VHOST_VDPA_NET_CVQ_ASID 1
 
-VHostNetState *vhost_vdpa_get_vhost_net(NetClientState *nc)
+static struct vhost_net *vhost_vdpa_get_vhost_net(NetClientState *nc)
 {
     VhostVDPAState *s = DO_UPCAST(VhostVDPAState, nc, nc);
     assert(nc->info->type == NET_CLIENT_DRIVER_VHOST_VDPA);
@@ -432,6 +432,7 @@ static NetClientInfo net_vhost_vdpa_info = {
         .set_vnet_le = vhost_vdpa_set_vnet_le,
         .check_peer_type = vhost_vdpa_check_peer_type,
         .set_steering_ebpf = vhost_vdpa_set_steering_ebpf,
+        .get_vhost_net = vhost_vdpa_get_vhost_net,
 };
 
 static int64_t vhost_vdpa_get_vring_group(int device_fd, unsigned vq_index,
@@ -1287,6 +1288,7 @@ static NetClientInfo net_vhost_vdpa_cvq_info = {
     .has_ufo = vhost_vdpa_has_ufo,
     .check_peer_type = vhost_vdpa_check_peer_type,
     .set_steering_ebpf = vhost_vdpa_set_steering_ebpf,
+    .get_vhost_net = vhost_vdpa_get_vhost_net,
 };
 
 /*