dpif: Add support for OVS_ACTION_ATTR_CT_CLEAR

This supports using the ct_clear action in the kernel datapath. To
preserve compatibility with current ct_clear behavior on old kernels, we
only pass this action down to the datapath if a probe reveals the
datapath actually supports it.

Signed-off-by: Eric Garver <e@erig.me>
Acked-by: William Tu <u9012063@gmail.com>
Acked-by: Flavio Leitner <fbl@sysclose.org>
Signed-off-by: Justin Pettit <jpettit@ovn.org>

5 files changed, 52 insertions, 2 deletions

diff --git a/ofproto/ofproto-dpif-ipfix.c b/ofproto/ofproto-dpif-ipfix.c
index a420903e9..97dbc3d29 100644
--- a/ofproto/ofproto-dpif-ipfix.c
+++ b/ofproto/ofproto-dpif-ipfix.c
@@ -2983,6 +2983,7 @@ dpif_ipfix_read_actions(const struct flow *flow,
         case OVS_ACTION_ATTR_TRUNC:
         case OVS_ACTION_ATTR_HASH:
         case OVS_ACTION_ATTR_CT:
+        case OVS_ACTION_ATTR_CT_CLEAR:
         case OVS_ACTION_ATTR_METER:
         case OVS_ACTION_ATTR_SET_MASKED:
         case OVS_ACTION_ATTR_SET:
diff --git a/ofproto/ofproto-dpif-sflow.c b/ofproto/ofproto-dpif-sflow.c
index e30a411f5..fb7589fda 100644
--- a/ofproto/ofproto-dpif-sflow.c
+++ b/ofproto/ofproto-dpif-sflow.c
@@ -1160,6 +1160,7 @@ dpif_sflow_read_actions(const struct flow *flow,
 	case OVS_ACTION_ATTR_RECIRC:
 	case OVS_ACTION_ATTR_HASH:
         case OVS_ACTION_ATTR_CT:
+    case OVS_ACTION_ATTR_CT_CLEAR:
         case OVS_ACTION_ATTR_METER:
 	    break;
 
diff --git a/ofproto/ofproto-dpif-xlate.c b/ofproto/ofproto-dpif-xlate.c
index 896d5e290..6c55545cb 100644
--- a/ofproto/ofproto-dpif-xlate.c
+++ b/ofproto/ofproto-dpif-xlate.c
@@ -5687,6 +5687,17 @@ compose_conntrack_action(struct xlate_ctx *ctx, struct ofpact_conntrack *ofc,
 }
 
 static void
+compose_ct_clear_action(struct xlate_ctx *ctx)
+{
+    clear_conntrack(ctx);
+    /* This action originally existed without dpif support. So to preserve
+     * compatibility, only append it if the dpif supports it. */
+    if (ctx->xbridge->support.ct_clear) {
+        nl_msg_put_flag(ctx->odp_actions,  OVS_ACTION_ATTR_CT_CLEAR);
+    }
+}
+
+static void
 rewrite_flow_encap_ethernet(struct xlate_ctx *ctx,
                             struct flow *flow,
                             struct flow_wildcards *wc)
@@ -6442,7 +6453,7 @@ do_xlate_actions(const struct ofpact *ofpacts, size_t ofpacts_len,
             break;
 
         case OFPACT_CT_CLEAR:
-            clear_conntrack(ctx);
+            compose_ct_clear_action(ctx);
             break;
 
         case OFPACT_NAT:
diff --git a/ofproto/ofproto-dpif.c b/ofproto/ofproto-dpif.c
index 6157b70ae..3365d4185 100644
--- a/ofproto/ofproto-dpif.c
+++ b/ofproto/ofproto-dpif.c
@@ -1255,6 +1255,39 @@ check_ct_eventmask(struct dpif_backer *backer)
     return !error;
 }
 
+/* Tests whether 'backer''s datapath supports the OVS_ACTION_ATTR_CT_CLEAR
+ * action. */
+static bool
+check_ct_clear(struct dpif_backer *backer)
+{
+    struct odputil_keybuf keybuf;
+    uint8_t actbuf[NL_A_FLAG_SIZE];
+    struct ofpbuf actions;
+    struct ofpbuf key;
+    struct flow flow;
+    bool supported;
+
+    struct odp_flow_key_parms odp_parms = {
+        .flow = &flow,
+        .probe = true,
+    };
+
+    memset(&flow, 0, sizeof flow);
+    ofpbuf_use_stack(&key, &keybuf, sizeof keybuf);
+    odp_flow_key_from_flow(&odp_parms, &key);
+
+    ofpbuf_use_stack(&actions, &actbuf, sizeof actbuf);
+    nl_msg_put_flag(&actions, OVS_ACTION_ATTR_CT_CLEAR);
+
+    supported = dpif_probe_feature(backer->dpif, "ct_clear", &key,
+                                   &actions, NULL);
+
+    VLOG_INFO("%s: Datapath %s ct_clear action",
+              dpif_name(backer->dpif), (supported) ? "supports"
+                                                   : "does not support");
+    return supported;
+}
+
 #define CHECK_FEATURE__(NAME, SUPPORT, FIELD, VALUE, ETHTYPE)               \
 static bool                                                                 \
 check_##NAME(struct dpif_backer *backer)                                    \
@@ -1316,6 +1349,7 @@ check_support(struct dpif_backer *backer)
     backer->rt_support.clone = check_clone(backer);
     backer->rt_support.sample_nesting = check_max_sample_nesting(backer);
     backer->rt_support.ct_eventmask = check_ct_eventmask(backer);
+    backer->rt_support.ct_clear = check_ct_clear(backer);
 
     /* Flow fields. */
     backer->rt_support.odp.ct_state = check_ct_state(backer);
diff --git a/ofproto/ofproto-dpif.h b/ofproto/ofproto-dpif.h
index c96e00e6a..6443cc5b2 100644
--- a/ofproto/ofproto-dpif.h
+++ b/ofproto/ofproto-dpif.h
@@ -173,7 +173,10 @@ struct group_dpif *group_dpif_lookup(struct ofproto_dpif *,
     DPIF_SUPPORT_FIELD(size_t, sample_nesting, "Sample nesting")            \
                                                                             \
     /* OVS_CT_ATTR_EVENTMASK supported by OVS_ACTION_ATTR_CT action. */     \
-    DPIF_SUPPORT_FIELD(bool, ct_eventmask, "Conntrack eventmask")
+    DPIF_SUPPORT_FIELD(bool, ct_eventmask, "Conntrack eventmask")           \
+                                                                            \
+    /* True if the datapath supports OVS_ACTION_ATTR_CT_CLEAR action. */    \
+    DPIF_SUPPORT_FIELD(bool, ct_clear, "Conntrack clear")
 
 /* Stores the various features which the corresponding backer supports. */
 struct dpif_backer_support {