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>

4 files changed, 2 insertions, 6 deletions

diff --git a/include/net/net.h b/include/net/net.h
index ac59b59..e67b375 100644
--- a/include/net/net.h
+++ b/include/net/net.h
@@ -67,6 +67,7 @@ typedef void (SocketReadStateFinalize)(SocketReadState *rs);
 typedef void (NetAnnounce)(NetClientState *);
 typedef bool (SetSteeringEBPF)(NetClientState *, int);
 typedef bool (NetCheckPeerType)(NetClientState *, ObjectClass *, Error **);
+typedef struct vhost_net *(GetVHostNet)(NetClientState *nc);
 
 typedef struct NetClientInfo {
     NetClientDriver type;
@@ -92,6 +93,7 @@ typedef struct NetClientInfo {
     NetAnnounce *announce;
     SetSteeringEBPF *set_steering_ebpf;
     NetCheckPeerType *check_peer_type;
+    GetVHostNet *get_vhost_net;
 } NetClientInfo;
 
 struct NetClientState {
diff --git a/include/net/tap.h b/include/net/tap.h
index 5d58551..6f34f13 100644
--- a/include/net/tap.h
+++ b/include/net/tap.h
@@ -33,7 +33,4 @@ int tap_disable(NetClientState *nc);
 
 int tap_get_fd(NetClientState *nc);
 
-struct vhost_net;
-struct vhost_net *tap_get_vhost_net(NetClientState *nc);
-
 #endif /* QEMU_NET_TAP_H */
diff --git a/include/net/vhost-user.h b/include/net/vhost-user.h
index 35bf619..0b233a2 100644
--- a/include/net/vhost-user.h
+++ b/include/net/vhost-user.h
@@ -12,7 +12,6 @@
 #define VHOST_USER_H
 
 struct vhost_net;
-struct vhost_net *vhost_user_get_vhost_net(NetClientState *nc);
 uint64_t vhost_user_get_acked_features(NetClientState *nc);
 void vhost_user_save_acked_features(NetClientState *nc);
 
diff --git a/include/net/vhost-vdpa.h b/include/net/vhost-vdpa.h
index b81f9a6..916ead3 100644
--- a/include/net/vhost-vdpa.h
+++ b/include/net/vhost-vdpa.h
@@ -14,8 +14,6 @@
 
 #define TYPE_VHOST_VDPA "vhost-vdpa"
 
-struct vhost_net *vhost_vdpa_get_vhost_net(NetClientState *nc);
-
 extern const int vdpa_feature_bits[];
 
 #endif /* VHOST_VDPA_H */