nfp: bpf: fall back to core NIC app if BPF not selected

If kernel config does not include BPF just replace the BPF
app handler with the handler for basic NIC.  The BPF app
will now be built only if BPF infrastructure is selected
in kernel config.
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: NSimon Horman <simon.horman@netronome.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/netronome/nfp/Makefile

@@ -27,8 +27,6 @@ nfp-objs := \
 	    nfp_net_sriov.o \
 	    nfp_netvf_main.o \
 	    nfp_port.o \
-	    bpf/main.o \
-	    bpf/offload.o \
 	    nic/main.o
 
 ifeq ($(CONFIG_NFP_APP_FLOWER),y)
@@ -44,6 +42,8 @@ endif
 
 ifeq ($(CONFIG_BPF_SYSCALL),y)
 nfp-objs += \
+	    bpf/main.o \
+	    bpf/offload.o \
 	    bpf/verifier.o \
 	    bpf/jit.o
 endif

drivers/net/ethernet/netronome/nfp/bpf/offload.c

@@ -150,9 +150,6 @@ nfp_net_bpf_offload_prepare(struct nfp_net *nn,
 	unsigned int max_mtu;
 	int ret;
 
-	if (!IS_ENABLED(CONFIG_BPF_SYSCALL))
-		return -EOPNOTSUPP;
-
 	ret = nfp_net_bpf_get_act(nn, cls_bpf);
 	if (ret < 0)
 		return ret;

drivers/net/ethernet/netronome/nfp/nfp_app.c

@@ -44,7 +44,11 @@
 
 static const struct nfp_app_type *apps[] = {
 	[NFP_APP_CORE_NIC]	= &app_nic,
+#ifdef CONFIG_BPF_SYSCALL
 	[NFP_APP_BPF_NIC]	= &app_bpf,
+#else
+	[NFP_APP_BPF_NIC]	= &app_nic,
+#endif
 #ifdef CONFIG_NFP_APP_FLOWER
 	[NFP_APP_FLOWER_NIC]	= &app_flower,
 #endif