Multiversioning: Device (tx) function constructor

Change-Id: I39f87ca161c891fb22462a23188982fef7c3243f
Signed-off-by: Mohsin Kazmi <sykazmi@cisco.com>

3 files changed, 45 insertions, 18 deletions

diff --git a/src/vnet/devices/virtio/vhost_user_output.c b/src/vnet/devices/virtio/vhost_user_output.c
index b41583708b3..9c65f249b4b 100644
--- a/src/vnet/devices/virtio/vhost_user_output.c
+++ b/src/vnet/devices/virtio/vhost_user_output.c
@@ -223,11 +223,9 @@ vhost_user_tx_copy (vhost_user_intf_t * vui, vhost_copy_t * cpy,
   return 0;
 }
 
-
-uword
-CLIB_MULTIARCH_FN (vhost_user_tx) (vlib_main_t * vm,
-				   vlib_node_runtime_t * node,
-				   vlib_frame_t * frame)
+VNET_DEVICE_CLASS_TX_FN (vhost_user_device_class) (vlib_main_t * vm,
+						   vlib_node_runtime_t *
+						   node, vlib_frame_t * frame)
 {
   u32 *buffers = vlib_frame_args (frame);
   u32 n_left = frame->n_vectors;
@@ -636,7 +634,6 @@ vhost_user_interface_admin_up_down (vnet_main_t * vnm, u32 hw_if_index,
 /* *INDENT-OFF* */
 VNET_DEVICE_CLASS (vhost_user_device_class) = {
   .name = "vhost-user",
-  .tx_function = vhost_user_tx,
   .tx_function_n_errors = VHOST_USER_TX_FUNC_N_ERROR,
   .tx_function_error_strings = vhost_user_tx_func_error_strings,
   .format_device_name = format_vhost_user_interface_name,
@@ -646,18 +643,6 @@ VNET_DEVICE_CLASS (vhost_user_device_class) = {
   .format_tx_trace = format_vhost_trace,
 };
 
-#if __x86_64__
-vlib_node_function_t __clib_weak vhost_user_tx_avx512;
-vlib_node_function_t __clib_weak vhost_user_tx_avx2;
-static void __clib_constructor
-vhost_user_tx_multiarch_select (void)
-{
-  if (vhost_user_tx_avx512 && clib_cpu_supports_avx512f ())
-    vhost_user_device_class.tx_function = vhost_user_tx_avx512;
-  else if (vhost_user_tx_avx2 && clib_cpu_supports_avx2 ())
-    vhost_user_device_class.tx_function = vhost_user_tx_avx2;
-}
-#endif
 #endif
 
 /* *INDENT-ON* */
diff --git a/src/vnet/interface.c b/src/vnet/interface.c
index ca4dc493aac..1e69ccbf6ea 100644
--- a/src/vnet/interface.c
+++ b/src/vnet/interface.c
@@ -1359,6 +1359,27 @@ vnet_interface_init (vlib_main_t * vm)
       {
 	c->index = vec_len (im->device_classes);
 	hash_set_mem (im->device_class_by_name, c->name, c->index);
+
+	if (c->tx_fn_registrations)
+	  {
+	    vlib_node_fn_registration_t *fnr = c->tx_fn_registrations;
+	    int priority = -1;
+
+	    /* to avoid confusion, please remove ".tx_function" statiement
+	       from VNET_DEVICE_CLASS() if using function candidates */
+	    ASSERT (c->tx_function == 0);
+
+	    while (fnr)
+	      {
+		if (fnr->priority > priority)
+		  {
+		    priority = fnr->priority;
+		    c->tx_function = fnr->function;
+		  }
+		fnr = fnr->next_registration;
+	      }
+	  }
+
 	vec_add1 (im->device_classes, c[0]);
 	c = c->next_class_registration;
       }
diff --git a/src/vnet/interface.h b/src/vnet/interface.h
index d869b0c70a2..e9adfe84cbf 100644
--- a/src/vnet/interface.h
+++ b/src/vnet/interface.h
@@ -195,6 +195,9 @@ typedef struct _vnet_device_class
   /* Transmit function. */
   vlib_node_function_t *tx_function;
 
+  /* Transmit function candidate registration with priority */
+  vlib_node_fn_registration_t *tx_fn_registrations;
+
   /* Error strings indexed by error code for this node. */
   char **tx_function_error_strings;
 
@@ -265,6 +268,24 @@ static void __vnet_rm_device_class_registration_##x (void)              \
 }                                                                       \
 __VA_ARGS__ vnet_device_class_t x
 
+#define VNET_DEVICE_CLASS_TX_FN(devclass)				\
+uword CLIB_MARCH_SFX (devclass##_tx_fn)();				\
+static vlib_node_fn_registration_t					\
+  CLIB_MARCH_SFX(devclass##_tx_fn_registration) =			\
+  { .function = &CLIB_MARCH_SFX (devclass##_tx_fn), };			\
+									\
+static void __clib_constructor						\
+CLIB_MARCH_SFX (devclass##_tx_fn_multiarch_register) (void)		\
+{									\
+  extern vnet_device_class_t devclass;					\
+  vlib_node_fn_registration_t *r;					\
+  r = &CLIB_MARCH_SFX (devclass##_tx_fn_registration);			\
+  r->priority = CLIB_MARCH_FN_PRIORITY();				\
+  r->next_registration = devclass.tx_fn_registrations;			\
+  devclass.tx_fn_registrations = r;					\
+}									\
+uword CLIB_CPU_OPTIMIZED CLIB_MARCH_SFX (devclass##_tx_fn)
+
 #define VLIB_DEVICE_TX_FUNCTION_CLONE_TEMPLATE(arch, fn, tgt)		\
   uword									\
   __attribute__ ((flatten))						\