net/mlx5: E-Switch, Support VLAN actions in the offloads mode

Many virtualization systems use a policy under which a vlan tag is
pushed to packets sent by guests, and popped before the packet is
forwarded to the VM.

The current generation of the mlx5 HW doesn't fully support that on
a per flow level. As such, we are addressing the above common use
case with the SRIOV e-Switch abilities to push vlan into packets
sent by VFs and pop vlan from packets forwarded to VFs.

The HW can match on the correct vlan being present in packets
forwarded to VFs (eSwitch steering is done before stripping
the tag), so this part is offloaded as is.

A common practice for vlans is to avoid both push vlan and pop vlan
for inter-host VM/VM (east-west) communication because in this case,
push on egress cancels out with pop on ingress.

For supporting that, we use a global eswitch vlan pop policy, hence
allowing guest A to communicate with both remote VM B and local VM C.
This works since the HW pops the vlan only if it exists (e.g for
C --> A packets but not for B --> A packets).

On the slow path, when a VF vport has an offloaded flow which involves
pushing vlans, wheres another flow is not currently offloaded, the
packets from the 2nd flow seen by the VF representor on the host have
vlan. The VF rep driver removes such vlan before calling into the host
networking stack.

Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 180 insertions, 0 deletions

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/eswitch_offloads.c b/drivers/net/ethernet/mellanox/mlx5/core/eswitch_offloads.c
index 781debb1acf8..c55ad8d00c05 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/eswitch_offloads.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/eswitch_offloads.c
@@ -89,6 +89,186 @@ mlx5_eswitch_add_offloaded_rule(struct mlx5_eswitch *esw,
 	return rule;
 }
 
+static int esw_set_global_vlan_pop(struct mlx5_eswitch *esw, u8 val)
+{
+	struct mlx5_eswitch_rep *rep;
+	int vf_vport, err = 0;
+
+	esw_debug(esw->dev, "%s applying global %s policy\n", __func__, val ? "pop" : "none");
+	for (vf_vport = 1; vf_vport < esw->enabled_vports; vf_vport++) {
+		rep = &esw->offloads.vport_reps[vf_vport];
+		if (!rep->valid)
+			continue;
+
+		err = __mlx5_eswitch_set_vport_vlan(esw, rep->vport, 0, 0, val);
+		if (err)
+			goto out;
+	}
+
+out:
+	return err;
+}
+
+static struct mlx5_eswitch_rep *
+esw_vlan_action_get_vport(struct mlx5_esw_flow_attr *attr, bool push, bool pop)
+{
+	struct mlx5_eswitch_rep *in_rep, *out_rep, *vport = NULL;
+
+	in_rep  = attr->in_rep;
+	out_rep = attr->out_rep;
+
+	if (push)
+		vport = in_rep;
+	else if (pop)
+		vport = out_rep;
+	else
+		vport = in_rep;
+
+	return vport;
+}
+
+static int esw_add_vlan_action_check(struct mlx5_esw_flow_attr *attr,
+				     bool push, bool pop, bool fwd)
+{
+	struct mlx5_eswitch_rep *in_rep, *out_rep;
+
+	if ((push || pop) && !fwd)
+		goto out_notsupp;
+
+	in_rep  = attr->in_rep;
+	out_rep = attr->out_rep;
+
+	if (push && in_rep->vport == FDB_UPLINK_VPORT)
+		goto out_notsupp;
+
+	if (pop && out_rep->vport == FDB_UPLINK_VPORT)
+		goto out_notsupp;
+
+	/* vport has vlan push configured, can't offload VF --> wire rules w.o it */
+	if (!push && !pop && fwd)
+		if (in_rep->vlan && out_rep->vport == FDB_UPLINK_VPORT)
+			goto out_notsupp;
+
+	/* protects against (1) setting rules with different vlans to push and
+	 * (2) setting rules w.o vlans (attr->vlan = 0) && w. vlans to push (!= 0)
+	 */
+	if (push && in_rep->vlan_refcount && (in_rep->vlan != attr->vlan))
+		goto out_notsupp;
+
+	return 0;
+
+out_notsupp:
+	return -ENOTSUPP;
+}
+
+int mlx5_eswitch_add_vlan_action(struct mlx5_eswitch *esw,
+				 struct mlx5_esw_flow_attr *attr)
+{
+	struct offloads_fdb *offloads = &esw->fdb_table.offloads;
+	struct mlx5_eswitch_rep *vport = NULL;
+	bool push, pop, fwd;
+	int err = 0;
+
+	push = !!(attr->action & MLX5_FLOW_CONTEXT_ACTION_VLAN_PUSH);
+	pop  = !!(attr->action & MLX5_FLOW_CONTEXT_ACTION_VLAN_POP);
+	fwd  = !!(attr->action & MLX5_FLOW_CONTEXT_ACTION_FWD_DEST);
+
+	err = esw_add_vlan_action_check(attr, push, pop, fwd);
+	if (err)
+		return err;
+
+	attr->vlan_handled = false;
+
+	vport = esw_vlan_action_get_vport(attr, push, pop);
+
+	if (!push && !pop && fwd) {
+		/* tracks VF --> wire rules without vlan push action */
+		if (attr->out_rep->vport == FDB_UPLINK_VPORT) {
+			vport->vlan_refcount++;
+			attr->vlan_handled = true;
+		}
+
+		return 0;
+	}
+
+	if (!push && !pop)
+		return 0;
+
+	if (!(offloads->vlan_push_pop_refcount)) {
+		/* it's the 1st vlan rule, apply global vlan pop policy */
+		err = esw_set_global_vlan_pop(esw, SET_VLAN_STRIP);
+		if (err)
+			goto out;
+	}
+	offloads->vlan_push_pop_refcount++;
+
+	if (push) {
+		if (vport->vlan_refcount)
+			goto skip_set_push;
+
+		err = __mlx5_eswitch_set_vport_vlan(esw, vport->vport, attr->vlan, 0,
+						    SET_VLAN_INSERT | SET_VLAN_STRIP);
+		if (err)
+			goto out;
+		vport->vlan = attr->vlan;
+skip_set_push:
+		vport->vlan_refcount++;
+	}
+out:
+	if (!err)
+		attr->vlan_handled = true;
+	return err;
+}
+
+int mlx5_eswitch_del_vlan_action(struct mlx5_eswitch *esw,
+				 struct mlx5_esw_flow_attr *attr)
+{
+	struct offloads_fdb *offloads = &esw->fdb_table.offloads;
+	struct mlx5_eswitch_rep *vport = NULL;
+	bool push, pop, fwd;
+	int err = 0;
+
+	if (!attr->vlan_handled)
+		return 0;
+
+	push = !!(attr->action & MLX5_FLOW_CONTEXT_ACTION_VLAN_PUSH);
+	pop  = !!(attr->action & MLX5_FLOW_CONTEXT_ACTION_VLAN_POP);
+	fwd  = !!(attr->action & MLX5_FLOW_CONTEXT_ACTION_FWD_DEST);
+
+	vport = esw_vlan_action_get_vport(attr, push, pop);
+
+	if (!push && !pop && fwd) {
+		/* tracks VF --> wire rules without vlan push action */
+		if (attr->out_rep->vport == FDB_UPLINK_VPORT)
+			vport->vlan_refcount--;
+
+		return 0;
+	}
+
+	if (push) {
+		vport->vlan_refcount--;
+		if (vport->vlan_refcount)
+			goto skip_unset_push;
+
+		vport->vlan = 0;
+		err = __mlx5_eswitch_set_vport_vlan(esw, vport->vport,
+						    0, 0, SET_VLAN_STRIP);
+		if (err)
+			goto out;
+	}
+
+skip_unset_push:
+	offloads->vlan_push_pop_refcount--;
+	if (offloads->vlan_push_pop_refcount)
+		return 0;
+
+	/* no more vlan rules, stop global vlan pop policy */
+	err = esw_set_global_vlan_pop(esw, 0);
+
+out:
+	return err;
+}
+
 static struct mlx5_flow_rule *
 mlx5_eswitch_add_send_to_vport_rule(struct mlx5_eswitch *esw, int vport, u32 sqn)
 {