[net-next,v2] net: openvswitch: Set OvS recirc_id from tc chain index

Offloaded OvS datapath rules are translated one to one to tc rules,
for example the following simplified OvS rule:

recirc_id(0),in_port(dev1),eth_type(0x0800),ct_state(-trk) actions:ct(),recirc(2)

Will be translated to the following tc rule:

$ tc filter add dev dev1 ingress \
	    prio 1 chain 0 proto ip \
		flower tcp ct_state -trk \
		action ct pipe \
		action goto chain 2

Received packets will first travel though tc, and if they aren't stolen
by it, like in the above rule, they will continue to OvS datapath.
Since we already did some actions (action ct in this case) which might
modify the packets, and updated action stats, we would like to continue
the proccessing with the correct recirc_id in OvS (here recirc_id(2))
where we left off.

To support this, introduce a new skb extension for tc, which
will be used for translating tc chain to ovs recirc_id to
handle these miss cases. Last tc chain index will be set
by tc goto chain action and read by OvS datapath.

Signed-off-by: Paul Blakey <paulb@mellanox.com>
Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
---
V2:
	Changed user_features to return not supported for requested user_features that aren't supported
	Added static key per pravin request, it is enabled on user_features request (And will be used by userspace to probe actual kernel support)

 include/linux/skbuff.h           | 13 +++++++++++++
 include/net/sch_generic.h        |  5 ++++-
 include/uapi/linux/openvswitch.h |  3 +++
 net/core/skbuff.c                |  6 ++++++
 net/openvswitch/datapath.c       | 38 +++++++++++++++++++++++++++++++++-----
 net/openvswitch/datapath.h       |  2 ++
 net/openvswitch/flow.c           | 13 +++++++++++++
 net/sched/Kconfig                | 13 +++++++++++++
 net/sched/act_api.c              |  1 +
 net/sched/cls_api.c              | 12 ++++++++++++
 10 files changed, 100 insertions(+), 6 deletions(-)

Regarding the user_features change, I tested the above patch with this one in
userspace that I'll send once this is accepted, togother with the rest
of connection tracking offload patches.

I also have a test for it, if anyone wants it.

Patch is:
lib/netdev-offloads-tc: Probe recirc tc sharing feature on first recirc_id rule

Signed-off-by: Paul Blakey <paulb@mellanox.com>
---
 datapath/linux/compat/include/linux/openvswitch.h |  3 ++
 lib/dpif-netdev.c                                 |  1 +
 lib/dpif-netlink.c                                | 61 +++++++++++++++++++----
 lib/dpif-provider.h                               |  2 +
 lib/dpif.c                                        |  9 ++++
 lib/dpif.h                                        |  2 +
 lib/netdev-offload-tc.c                           | 33 ++++++++++--
 lib/netdev-offload.h                              |  2 +-
 8 files changed, 100 insertions(+), 13 deletions(-)

diff --git a/datapath/linux/compat/include/linux/openvswitch.h b/datapath/linux/compat/include/linux/openvswitch.h
index 65a003a..921ef5b 100644
--- a/datapath/linux/compat/include/linux/openvswitch.h
+++ b/datapath/linux/compat/include/linux/openvswitch.h
@@ -143,6 +143,9 @@ struct ovs_vport_stats {
 /* Allow datapath to associate multiple Netlink PIDs to each vport */
 #define OVS_DP_F_VPORT_PIDS	(1 << 1)
 
+/* Allow tc offload recirc sharing */
+#define OVS_DP_F_TC_RECIRC_SHARING  (1 << 2)
+
 /* Fixed logical ports. */
 #define OVSP_LOCAL      ((__u32)0)
 
diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
index d0a1c58..fd8275f 100644
--- a/lib/dpif-netdev.c
+++ b/lib/dpif-netdev.c
@@ -7489,6 +7489,7 @@ const struct dpif_class dpif_netdev_class = {
     dpif_netdev_run,
     dpif_netdev_wait,
     dpif_netdev_get_stats,
+    NULL,                      /* set_features */
     dpif_netdev_port_add,
     dpif_netdev_port_del,
     dpif_netdev_port_set_config,
diff --git a/lib/dpif-netlink.c b/lib/dpif-netlink.c
index 07a9ddd..15e6057 100644
--- a/lib/dpif-netlink.c
+++ b/lib/dpif-netlink.c
@@ -192,6 +192,7 @@ struct dpif_handler {
 struct dpif_netlink {
     struct dpif dpif;
     int dp_ifindex;
+    uint32_t user_features;
 
     /* Upcall messages. */
     struct fat_rwlock upcall_lock;
@@ -303,7 +304,6 @@ dpif_netlink_enumerate(struct sset *all_dps,
     if (error) {
         return error;
     }
-
     ofpbuf_use_stub(&buf, reply_stub, sizeof reply_stub);
     dpif_netlink_dp_dump_start(&dump);
     while (nl_dump_next(&dump, &msg, &buf)) {
@@ -333,15 +333,26 @@ dpif_netlink_open(const struct dpif_class *class OVS_UNUSED, const char *name,
 
     /* Create or look up datapath. */
     dpif_netlink_dp_init(&dp_request);
+    upcall_pid = 0;
+    dp_request.upcall_pid = &upcall_pid;
+    dp_request.name = name;
+
     if (create) {
         dp_request.cmd = OVS_DP_CMD_NEW;
-        upcall_pid = 0;
-        dp_request.upcall_pid = &upcall_pid;
     } else {
+        dp_request.cmd = OVS_DP_CMD_GET;
+
+        error = dpif_netlink_dp_transact(&dp_request, &dp, &buf);
+        if (error)  {
+            return error;
+        }
+        dp_request.user_features = dp.user_features;
+        ofpbuf_delete(buf);
+
         /* Use OVS_DP_CMD_SET to report user features */
         dp_request.cmd = OVS_DP_CMD_SET;
     }
-    dp_request.name = name;
+
     dp_request.user_features |= OVS_DP_F_UNALIGNED;
     dp_request.user_features |= OVS_DP_F_VPORT_PIDS;
     error = dpif_netlink_dp_transact(&dp_request, &dp, &buf);
@@ -367,6 +378,7 @@ open_dpif(const struct dpif_netlink_dp *dp, struct dpif **dpifp)
               dp->dp_ifindex, dp->dp_ifindex);
 
     dpif->dp_ifindex = dp->dp_ifindex;
+    dpif->user_features = dp->user_features;
     *dpifp = &dpif->dpif;
 
     return 0;
@@ -662,6 +674,31 @@ dpif_netlink_get_stats(const struct dpif *dpif_, struct dpif_dp_stats *stats)
     return error;
 }
 
+static int
+dpif_netlink_set_features(struct dpif *dpif_, uint32_t new_features)
+{
+    struct dpif_netlink *dpif = dpif_netlink_cast(dpif_);
+    struct dpif_netlink_dp request, reply;
+    struct ofpbuf *bufp;
+    int error;
+
+    dpif_netlink_dp_init(&request);
+    request.cmd = OVS_DP_CMD_SET;
+    request.dp_ifindex = dpif->dp_ifindex;
+    request.user_features = dpif->user_features | new_features;
+
+    error = dpif_netlink_dp_transact(&request, &reply, &bufp);
+    if (!error) {
+        dpif->user_features = reply.user_features;
+        ofpbuf_delete(bufp);
+        if (!(dpif->user_features & new_features)) {
+            return -EOPNOTSUPP;
+        }
+    }
+
+    return error;
+}
+
 static const char *
 get_vport_type(const struct dpif_netlink_vport *vport)
 {
@@ -1989,7 +2026,6 @@ static int
 parse_flow_put(struct dpif_netlink *dpif, struct dpif_flow_put *put)
 {
     static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 20);
-    const struct dpif_class *dpif_class = dpif->dpif.dpif_class;
     struct match match;
     odp_port_t in_port;
     const struct nlattr *nla;
@@ -2011,7 +2047,7 @@ parse_flow_put(struct dpif_netlink *dpif, struct dpif_flow_put *put)
     }
 
     in_port = match.flow.in_port.odp_port;
-    dev = netdev_ports_get(in_port, dpif_class);
+    dev = netdev_ports_get(in_port, dpif->dpif.dpif_class);
     if (!dev) {
         return EOPNOTSUPP;
     }
@@ -2024,7 +2060,7 @@ parse_flow_put(struct dpif_netlink *dpif, struct dpif_flow_put *put)
             odp_port_t out_port;
 
             out_port = nl_attr_get_odp_port(nla);
-            outdev = netdev_ports_get(out_port, dpif_class);
+            outdev = netdev_ports_get(out_port, dpif->dpif.dpif_class);
             if (!outdev) {
                 err = EOPNOTSUPP;
                 goto out;
@@ -2040,7 +2076,7 @@ parse_flow_put(struct dpif_netlink *dpif, struct dpif_flow_put *put)
         }
     }
 
-    info.dpif_class = dpif_class;
+    info.dpif = &dpif->dpif;
     info.tp_dst_port = dst_port;
     info.tunnel_csum_on = csum_on;
     err = netdev_flow_put(dev, &match,
@@ -3394,6 +3430,7 @@ const struct dpif_class dpif_netlink_class = {
     dpif_netlink_run,
     NULL,                       /* wait */
     dpif_netlink_get_stats,
+    dpif_netlink_set_features,
     dpif_netlink_port_add,
     dpif_netlink_port_del,
     NULL,                       /* port_set_config */
@@ -3702,6 +3739,9 @@ dpif_netlink_dp_from_ofpbuf(struct dpif_netlink_dp *dp, const struct ofpbuf *buf
         [OVS_DP_ATTR_MEGAFLOW_STATS] = {
                         NL_POLICY_FOR(struct ovs_dp_megaflow_stats),
                         .optional = true },
+        [OVS_DP_ATTR_USER_FEATURES] = {
+                        .type = NL_A_U32,
+                        .optional = true },
     };
 
     dpif_netlink_dp_init(dp);
@@ -3730,6 +3770,10 @@ dpif_netlink_dp_from_ofpbuf(struct dpif_netlink_dp *dp, const struct ofpbuf *buf
         dp->megaflow_stats = nl_attr_get(a[OVS_DP_ATTR_MEGAFLOW_STATS]);
     }
 
+    if (a[OVS_DP_ATTR_USER_FEATURES]) {
+        dp->user_features = nl_attr_get_u32(a[OVS_DP_ATTR_USER_FEATURES]);
+    }
+
     return 0;
 }
 
@@ -3802,7 +3846,6 @@ dpif_netlink_dp_transact(const struct dpif_netlink_dp *request,
     dpif_netlink_dp_to_ofpbuf(request, request_buf);
     error = nl_transact(NETLINK_GENERIC, request_buf, bufp);
     ofpbuf_delete(request_buf);
-
     if (reply) {
         dpif_netlink_dp_init(reply);
         if (!error) {
diff --git a/lib/dpif-provider.h b/lib/dpif-provider.h
index 12898b9..8c8bc77 100644
--- a/lib/dpif-provider.h
+++ b/lib/dpif-provider.h
@@ -187,6 +187,8 @@ struct dpif_class {
     /* Retrieves statistics for 'dpif' into 'stats'. */
     int (*get_stats)(const struct dpif *dpif, struct dpif_dp_stats *stats);
 
+    int (*set_features)(struct dpif *dpif, uint32_t user_features);
+
     /* Adds 'netdev' as a new port in 'dpif'.  If '*port_no' is not
      * ODPP_NONE, attempts to use that as the port's port number.
      *
diff --git a/lib/dpif.c b/lib/dpif.c
index c88b210..dc13655 100644
--- a/lib/dpif.c
+++ b/lib/dpif.c
@@ -543,6 +543,15 @@ dpif_get_dp_stats(const struct dpif *dpif, struct dpif_dp_stats *stats)
     return error;
 }
 
+int
+dpif_set_features(struct dpif *dpif, uint32_t new_features)
+{
+    int error = dpif->dpif_class->set_features(dpif, new_features);
+
+    log_operation(dpif, "set_features", error);
+    return error;
+}
+
 const char *
 dpif_port_open_type(const char *datapath_type, const char *port_type)
 {
diff --git a/lib/dpif.h b/lib/dpif.h
index 289d574..c7bb48f 100644
--- a/lib/dpif.h
+++ b/lib/dpif.h
@@ -435,6 +435,8 @@ struct dpif_dp_stats {
 };
 int dpif_get_dp_stats(const struct dpif *, struct dpif_dp_stats *);
 
+int dpif_set_features(struct dpif *, uint32_t new_features);
+
 
 /* Port operations. */
 
diff --git a/lib/netdev-offload-tc.c b/lib/netdev-offload-tc.c
index 60d5a42..4e85585 100644
--- a/lib/netdev-offload-tc.c
+++ b/lib/netdev-offload-tc.c
@@ -38,6 +38,7 @@
 #include "tc.h"
 #include "unaligned.h"
 #include "util.h"
+#include "dpif-provider.h"
 
 VLOG_DEFINE_THIS_MODULE(netdev_offload_tc);
 
@@ -1354,6 +1355,25 @@ flower_match_to_tun_opt(struct tc_flower *flower, const struct flow_tnl *tnl,
     flower->mask.tunnel.metadata.present.len = tnl->metadata.present.len;
 }
 
+static bool
+recirc_id_sharing_support(struct dpif *dpif)
+{
+    static struct ovsthread_once once = OVSTHREAD_ONCE_INITIALIZER;
+    static bool supported = false;
+    int err;
+
+    if (ovsthread_once_start(&once)) {
+        err = dpif_set_features(dpif, OVS_DP_F_TC_RECIRC_SHARING);
+        supported = err ? supported : true;
+        if (supported) {
+            VLOG_INFO("probe tc: tc recirc id sharing with OvS datapath is supported.");
+        }
+        ovsthread_once_done(&once);
+    }
+
+    return supported;
+}
+
 static int
 netdev_tc_flow_put(struct netdev *netdev, struct match *match,
                    struct nlattr *actions, size_t actions_len,
@@ -1371,7 +1391,7 @@ netdev_tc_flow_put(struct netdev *netdev, struct match *match,
     uint32_t block_id = 0;
     struct nlattr *nla;
     struct tc_id id;
-    uint32_t chain;
+    uint32_t chain = 0;
     size_t left;
     int prio = 0;
     int ifindex;
@@ -1386,7 +1406,13 @@ netdev_tc_flow_put(struct netdev *netdev, struct match *match,
 
     memset(&flower, 0, sizeof flower);
 
-    chain = key->recirc_id;
+    if (key->recirc_id) {
+        if (recirc_id_sharing_support(info->dpif)) {
+            chain = key->recirc_id;
+        } else {
+            return -EOPNOTSUPP;
+        }
+    }
     mask->recirc_id = 0;
 
     if (flow_tnl_dst_is_set(&key->tunnel)) {
@@ -1634,7 +1660,8 @@ netdev_tc_flow_put(struct netdev *netdev, struct match *match,
         action = &flower.actions[flower.action_count];
         if (nl_attr_type(nla) == OVS_ACTION_ATTR_OUTPUT) {
             odp_port_t port = nl_attr_get_odp_port(nla);
-            struct netdev *outdev = netdev_ports_get(port, info->dpif_class);
+            struct netdev *outdev = netdev_ports_get(port,
+                                                     info->dpif->dpif_class);
 
             action->out.ifindex_out = netdev_get_ifindex(outdev);
             action->out.ingress = is_internal_port(netdev_get_type(outdev));
diff --git a/lib/netdev-offload.h b/lib/netdev-offload.h
index 97a5006..d852fe2 100644
--- a/lib/netdev-offload.h
+++ b/lib/netdev-offload.h
@@ -62,7 +62,7 @@ struct netdev_flow_dump {
 
 /* Flow offloading. */
 struct offload_info {
-    const struct dpif_class *dpif_class;
+    struct dpif *dpif;
     ovs_be16 tp_dst_port; /* Destination port for tunnel in SET action */
     uint8_t tunnel_csum_on; /* Tunnel header with checksum */

From: Paul Blakey <paulb@mellanox.com>
Date: Tue, 20 Aug 2019 15:30:51 +0300

> @@ -4050,6 +4060,9 @@ enum skb_ext_id {
>  #ifdef CONFIG_XFRM
>  	SKB_EXT_SEC_PATH,
>  #endif
> +#if IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
> +	TC_SKB_EXT,
> +#endif
>  	SKB_EXT_NUM, /* must be last */
>  };

Sorry, no.

The SKB extensions are not a dumping ground for people to use when they can't
figure out another more reasonable place to put their values.  Try to use
the normal cb[], and if you can't you must explain in exhaustive detail
why you cannot in any way whatsoever make that work.

Again, SKB extensions are not a dumping ground.

On 8/22/2019 6:57 AM, David Miller wrote:

> From: Paul Blakey <paulb@mellanox.com>
> Date: Tue, 20 Aug 2019 15:30:51 +0300
>
>> @@ -4050,6 +4060,9 @@ enum skb_ext_id {
>>   #ifdef CONFIG_XFRM
>>   	SKB_EXT_SEC_PATH,
>>   #endif
>> +#if IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
>> +	TC_SKB_EXT,
>> +#endif
>>   	SKB_EXT_NUM, /* must be last */
>>   };
> Sorry, no.
>
> The SKB extensions are not a dumping ground for people to use when they can't
> figure out another more reasonable place to put their values.  Try to use
> the normal cb[], and if you can't you must explain in exhaustive detail
> why you cannot in any way whatsoever make that work.
>
> Again, SKB extensions are not a dumping ground.
Hi,
The general context of this skb extension patch is hardware offload of 
multi chain rules.
This patch shows only one usage of this extension which is by tc -> OvS 
miss path.
But we also plan to reuse this extension to pass information from 
HW/Driver -> tc miss path.

In tc multi chain rules scenarios, some of the rules might be offloaded
and some not (e.g skip_hw, unsupported rules by HW, vxlan encapsulation, 
offload order, etc).
Therefore, HW can miss at any point of the processing chain.
SW will need to continue processing in correct tc chain where the HW 
left off, as HW might have modified the packet and updated stats for it.
This scenario can reuse this tc SKB extension to restore the tc chain.

Skb control block acts a scratchpad area for storing temporary 
information and isn't suppose
to be used to pass around information between different layers of 
processing.
HW/Driver -> tc - >OvS  are different layers, and not necessarily 
processing the packet one after another.
There can be bridges, tunnel devices, VLAN devices, Netfilter 
(Conntrack) and a host of other entities processing the packet in between
so we can't guarantee the control block integrity between this main 
processing entities (HW/Driver, Tc, Ovs).
So if we'll use the control block, it will restrict such use cases.
For example, the napi API which we use, uses the control block and comes 
right after our driver layer.
This will overwrite any usage of CB by us.


Thanks,
Paul B.