On Fri, Apr 05, 2024 at 11:39:58AM +0200, Eelco Chaudron wrote:
> 
> 
> On 3 Apr 2024, at 16:35, Eric Garver wrote:
> 
> > Kernel support has been added for this action. As such, we need to probe
> > the datapath for support.
> >
> > Signed-off-by: Eric Garver <e...@garver.life>
> > ---
> >  include/linux/openvswitch.h |  2 +-
> >  lib/dpif.c                  |  6 ++-
> >  lib/dpif.h                  |  2 +-
> >  ofproto/ofproto-dpif.c      | 77 ++++++++++++++++++++++++++++++++++---
> >  ofproto/ofproto-dpif.h      |  4 +-
> >  5 files changed, 81 insertions(+), 10 deletions(-)
> >
> > diff --git a/include/linux/openvswitch.h b/include/linux/openvswitch.h
> > index d18754c84f62..d9fb991ef234 100644
> > --- a/include/linux/openvswitch.h
> > +++ b/include/linux/openvswitch.h
> > @@ -1086,11 +1086,11 @@ enum ovs_action_attr {
> >     OVS_ACTION_ATTR_CHECK_PKT_LEN, /* Nested OVS_CHECK_PKT_LEN_ATTR_*. */
> >     OVS_ACTION_ATTR_ADD_MPLS,     /* struct ovs_action_add_mpls. */
> >     OVS_ACTION_ATTR_DEC_TTL,      /* Nested OVS_DEC_TTL_ATTR_*. */
> > +   OVS_ACTION_ATTR_DROP,         /* u32 xlate_error. */
> >
> >  #ifndef __KERNEL__
> >     OVS_ACTION_ATTR_TUNNEL_PUSH,   /* struct ovs_action_push_tnl*/
> >     OVS_ACTION_ATTR_TUNNEL_POP,    /* u32 port number. */
> > -   OVS_ACTION_ATTR_DROP,          /* u32 xlate_error. */
> >     OVS_ACTION_ATTR_LB_OUTPUT,     /* u32 bond-id. */
> >  #endif
> >     __OVS_ACTION_ATTR_MAX,        /* Nothing past this will be accepted
> > diff --git a/lib/dpif.c b/lib/dpif.c
> > index 0f480bec48d0..23eb18495a66 100644
> > --- a/lib/dpif.c
> > +++ b/lib/dpif.c
> > @@ -28,6 +28,7 @@
> >  #include "dpctl.h"
> >  #include "dpif-netdev.h"
> >  #include "flow.h"
> > +#include "netdev-offload.h"
> >  #include "netdev-provider.h"
> >  #include "netdev.h"
> >  #include "netlink.h"
> > @@ -1935,9 +1936,10 @@ dpif_supports_tnl_push_pop(const struct dpif *dpif)
> >  }
> >
> >  bool
> > -dpif_supports_explicit_drop_action(const struct dpif *dpif)
> > +dpif_may_support_explicit_drop_action(const struct dpif *dpif)
> >  {
> > -    return dpif_is_netdev(dpif);
> > +    /* TC does not support offloading this action. */
> > +    return dpif_is_netdev(dpif) || !netdev_is_flow_api_enabled();
> >  }
> >
> >  bool
> > diff --git a/lib/dpif.h b/lib/dpif.h
> > index 0f2dc2ef3c55..a764e8a592bd 100644
> > --- a/lib/dpif.h
> > +++ b/lib/dpif.h
> > @@ -940,7 +940,7 @@ int dpif_get_pmds_for_port(const struct dpif * dpif, 
> > odp_port_t port_no,
> >
> >  char *dpif_get_dp_version(const struct dpif *);
> >  bool dpif_supports_tnl_push_pop(const struct dpif *);
> > -bool dpif_supports_explicit_drop_action(const struct dpif *);
> > +bool dpif_may_support_explicit_drop_action(const struct dpif *);
> >  bool dpif_synced_dp_layers(struct dpif *);
> >
> >  /* Log functions. */
> > diff --git a/ofproto/ofproto-dpif.c b/ofproto/ofproto-dpif.c
> > index c4e2e867ecdc..32d037be607c 100644
> > --- a/ofproto/ofproto-dpif.c
> > +++ b/ofproto/ofproto-dpif.c
> > @@ -221,6 +221,7 @@ static void ct_zone_config_init(struct dpif_backer 
> > *backer);
> >  static void ct_zone_config_uninit(struct dpif_backer *backer);
> >  static void ct_zone_timeout_policy_sweep(struct dpif_backer *backer);
> >  static void ct_zone_limits_commit(struct dpif_backer *backer);
> > +static bool recheck_support_explicit_drop_action(struct dpif_backer 
> > *backer);
> >
> >  static inline struct ofproto_dpif *
> >  ofproto_dpif_cast(const struct ofproto *ofproto)
> > @@ -391,6 +392,10 @@ type_run(const char *type)
> >          udpif_set_threads(backer->udpif, n_handlers, n_revalidators);
> >      }
> >
> > +    if (recheck_support_explicit_drop_action(backer)) {
> > +        backer->need_revalidate = REV_RECONFIGURE;
> > +    }
> > +
> >      if (backer->need_revalidate) {
> >          struct ofproto_dpif *ofproto;
> >          struct simap_node *node;
> > @@ -855,7 +860,11 @@ ovs_native_tunneling_is_on(struct ofproto_dpif 
> > *ofproto)
> >  bool
> >  ovs_explicit_drop_action_supported(struct ofproto_dpif *ofproto)
> >  {
> > -    return ofproto->backer->rt_support.explicit_drop_action;
> > +    bool value;
> > +
> > +    atomic_read_relaxed(&ofproto->backer->rt_support.explicit_drop_action,
> > +                        &value);
> > +    return value;
> >  }
> >
> >  bool
> > @@ -1379,6 +1388,40 @@ check_ct_timeout_policy(struct dpif_backer *backer)
> >      return !error;
> >  }
> >
> > +/* Tests whether backer's datapath supports the OVS_ACTION_ATTR_DROP 
> > action. */
> > +static bool
> > +check_drop_action(struct dpif_backer *backer)
> > +{
> > +    struct odputil_keybuf keybuf;
> > +    uint8_t actbuf[NL_A_U32_SIZE];
> > +    struct ofpbuf actions;
> > +    struct ofpbuf key;
> > +    bool supported;
> > +
> > +    struct flow flow = {
> > +        .dl_type = CONSTANT_HTONS(0x1234), /* bogus */
> > +    };
> > +    struct odp_flow_key_parms odp_parms = {
> > +        .flow = &flow,
> > +        .probe = true,
> > +    };
> > +
> > +    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_u32(&actions, OVS_ACTION_ATTR_DROP, XLATE_OK);
> > +
> > +    supported = dpif_may_support_explicit_drop_action(backer->dpif) &&
> > +                dpif_probe_feature(backer->dpif, "drop", &key, &actions, 
> > NULL);
> > +
> > +    VLOG_INFO("%s: Datapath %s explicit drop action",
> > +              dpif_name(backer->dpif),
> > +              (supported) ? "supports" : "does not support");
> > +
> > +    return supported;
> > +}
> > +
> >  /* Tests whether 'backer''s datapath supports the all-zero SNAT case. */
> >  static bool
> >  dpif_supports_ct_zero_snat(struct dpif_backer *backer)
> > @@ -1649,8 +1692,8 @@ check_support(struct dpif_backer *backer)
> >      backer->rt_support.max_hash_alg = check_max_dp_hash_alg(backer);
> >      backer->rt_support.check_pkt_len = check_check_pkt_len(backer);
> >      backer->rt_support.ct_timeout = check_ct_timeout_policy(backer);
> > -    backer->rt_support.explicit_drop_action =
> > -        dpif_supports_explicit_drop_action(backer->dpif);
> > +    atomic_store_relaxed(&backer->rt_support.explicit_drop_action,
> > +                         check_drop_action(backer));
> >      backer->rt_support.lb_output_action =
> >          dpif_supports_lb_output_action(backer->dpif);
> >      backer->rt_support.ct_zero_snat = dpif_supports_ct_zero_snat(backer);
> > @@ -1667,6 +1710,28 @@ check_support(struct dpif_backer *backer)
> >      backer->rt_support.odp.nd_ext = check_nd_extensions(backer);
> >  }
> >
> > +/* TC does not support offloading the explicit drop action. As such we 
> > need to
> > + * re-probe the datapath if hw-offload has been modified.
> > + * Note: We don't support true --> false transition as that requires a 
> > restart.
> > + * See netdev_set_flow_api_enabled(). */
> > +static bool
> > +recheck_support_explicit_drop_action(struct dpif_backer *backer)
> > +{
> > +    bool explicit_drop_action;
> > +
> > +    atomic_read_relaxed(&backer->rt_support.explicit_drop_action,
> > +                        &explicit_drop_action);
> > +
> > +    if (explicit_drop_action
> > +        && !dpif_may_support_explicit_drop_action(backer->dpif)) {
> > +        ovs_assert(!check_drop_action(backer));
> 
> If we only call this for the log message, would just adding the log message 
> here not be better?
> It avoids the installation of a flow, and I have not thought this through, 
> but it might confuse the revalidator.

So you and Ilya would rather I insert a VLOG_INFO() here? That's fine
with me.

Can we agree on the message before I post another revision?

  VLOG_INFO("%s: Datapath supports explicit drop action, "
            "but disabled due to hw-offload=true.",
            dpif_name(backer->dpif))

Is that agreeable?

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