nfp: flower: offload phys port MTU change

Trigger a port mod message to request an MTU change on the NIC when any
physical port representor is assigned a new MTU value. The driver waits
10 msec for an ack that the FW has set the MTU. If no ack is received the
request is rejected and an appropriate warning flagged.

Rather than maintain an MTU queue per repr, one is maintained per app.
Because the MTU ndo is protected by the rtnl lock, there can never be
contention here. Portmod messages from the NIC are also protected by
rtnl so we first check if the portmod is an ack and, if so, handle outside
rtnl and the cmsg work queue.

Acks are detected by the marking of a bit in a portmod response. They are
then verfied by checking the port number and MTU value expected by the
app. If the expected MTU is 0 then no acks are currently expected.

Also, ensure that the packet headroom reserved by the flower firmware is
considered when accepting an MTU change on any repr.

Signed-off-by: John Hurley <john.hurley@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 85 insertions, 2 deletions

diff --git a/drivers/net/ethernet/netronome/nfp/flower/main.c b/drivers/net/ethernet/netronome/nfp/flower/main.c
index 742d6f1575b5..6357e0720f43 100644
--- a/drivers/net/ethernet/netronome/nfp/flower/main.c
+++ b/drivers/net/ethernet/netronome/nfp/flower/main.c
@@ -52,6 +52,8 @@
 
 #define NFP_FLOWER_ALLOWED_VER 0x0001000000010000UL
 
+#define NFP_FLOWER_FRAME_HEADROOM	158
+
 static const char *nfp_flower_extra_cap(struct nfp_app *app, struct nfp_net *nn)
 {
 	return "FLOWER";
@@ -157,7 +159,7 @@ nfp_flower_repr_netdev_open(struct nfp_app *app, struct nfp_repr *repr)
 {
 	int err;
 
-	err = nfp_flower_cmsg_portmod(repr, true);
+	err = nfp_flower_cmsg_portmod(repr, true, repr->netdev->mtu, false);
 	if (err)
 		return err;
 
@@ -171,7 +173,7 @@ nfp_flower_repr_netdev_stop(struct nfp_app *app, struct nfp_repr *repr)
 {
 	netif_tx_disable(repr->netdev);
 
-	return nfp_flower_cmsg_portmod(repr, false);
+	return nfp_flower_cmsg_portmod(repr, false, repr->netdev->mtu, false);
 }
 
 static int
@@ -521,6 +523,9 @@ static int nfp_flower_init(struct nfp_app *app)
 	INIT_WORK(&app_priv->cmsg_work, nfp_flower_cmsg_process_rx);
 	init_waitqueue_head(&app_priv->reify_wait_queue);
 
+	init_waitqueue_head(&app_priv->mtu_conf.wait_q);
+	spin_lock_init(&app_priv->mtu_conf.lock);
+
 	err = nfp_flower_metadata_init(app);
 	if (err)
 		goto err_free_app_priv;
@@ -552,6 +557,81 @@ static void nfp_flower_clean(struct nfp_app *app)
 	app->priv = NULL;
 }
 
+static int
+nfp_flower_check_mtu(struct nfp_app *app, struct net_device *netdev,
+		     int new_mtu)
+{
+	/* The flower fw reserves NFP_FLOWER_FRAME_HEADROOM bytes of the
+	 * supported max MTU to allow for appending tunnel headers. To prevent
+	 * unexpected behaviour this needs to be accounted for.
+	 */
+	if (new_mtu > netdev->max_mtu - NFP_FLOWER_FRAME_HEADROOM) {
+		nfp_err(app->cpp, "New MTU (%d) is not valid\n", new_mtu);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static bool nfp_flower_check_ack(struct nfp_flower_priv *app_priv)
+{
+	bool ret;
+
+	spin_lock_bh(&app_priv->mtu_conf.lock);
+	ret = app_priv->mtu_conf.ack;
+	spin_unlock_bh(&app_priv->mtu_conf.lock);
+
+	return ret;
+}
+
+static int
+nfp_flower_repr_change_mtu(struct nfp_app *app, struct net_device *netdev,
+			   int new_mtu)
+{
+	struct nfp_flower_priv *app_priv = app->priv;
+	struct nfp_repr *repr = netdev_priv(netdev);
+	int err, ack;
+
+	/* Only need to config FW for physical port MTU change. */
+	if (repr->port->type != NFP_PORT_PHYS_PORT)
+		return 0;
+
+	if (!(app_priv->flower_ext_feats & NFP_FL_NBI_MTU_SETTING)) {
+		nfp_err(app->cpp, "Physical port MTU setting not supported\n");
+		return -EINVAL;
+	}
+
+	spin_lock_bh(&app_priv->mtu_conf.lock);
+	app_priv->mtu_conf.ack = false;
+	app_priv->mtu_conf.requested_val = new_mtu;
+	app_priv->mtu_conf.portnum = repr->dst->u.port_info.port_id;
+	spin_unlock_bh(&app_priv->mtu_conf.lock);
+
+	err = nfp_flower_cmsg_portmod(repr, netif_carrier_ok(netdev), new_mtu,
+				      true);
+	if (err) {
+		spin_lock_bh(&app_priv->mtu_conf.lock);
+		app_priv->mtu_conf.requested_val = 0;
+		spin_unlock_bh(&app_priv->mtu_conf.lock);
+		return err;
+	}
+
+	/* Wait for fw to ack the change. */
+	ack = wait_event_timeout(app_priv->mtu_conf.wait_q,
+				 nfp_flower_check_ack(app_priv),
+				 msecs_to_jiffies(10));
+
+	if (!ack) {
+		spin_lock_bh(&app_priv->mtu_conf.lock);
+		app_priv->mtu_conf.requested_val = 0;
+		spin_unlock_bh(&app_priv->mtu_conf.lock);
+		nfp_warn(app->cpp, "MTU change not verified with fw\n");
+		return -EIO;
+	}
+
+	return 0;
+}
+
 static int nfp_flower_start(struct nfp_app *app)
 {
 	return nfp_tunnel_config_start(app);
@@ -574,6 +654,9 @@ const struct nfp_app_type app_flower = {
 	.init		= nfp_flower_init,
 	.clean		= nfp_flower_clean,
 
+	.check_mtu	= nfp_flower_check_mtu,
+	.repr_change_mtu  = nfp_flower_repr_change_mtu,
+
 	.vnic_alloc	= nfp_flower_vnic_alloc,
 	.vnic_init	= nfp_flower_vnic_init,
 	.vnic_clean	= nfp_flower_vnic_clean,