On Wed, Jul 10, 2024 at 01:28:29PM GMT, Ilya Maximets wrote:
> On 7/7/24 22:08, Adrian Moreno wrote:
> > Only kernel datapath supports this action so add a function in dpif.c
> > that checks for that.
> >
> > Signed-off-by: Adrian Moreno <amore...@redhat.com>
> > ---
> > lib/dpif.c | 7 +++++++
> > lib/dpif.h | 1 +
> > ofproto/ofproto-dpif.c | 43 ++++++++++++++++++++++++++++++++++++++++++
> > ofproto/ofproto-dpif.h | 7 ++++++-
> > 4 files changed, 57 insertions(+), 1 deletion(-)
> >
> > diff --git a/lib/dpif.c b/lib/dpif.c
> > index 71728badc..0a964ba89 100644
> > --- a/lib/dpif.c
> > +++ b/lib/dpif.c
> > @@ -1953,6 +1953,13 @@ dpif_supports_lb_output_action(const struct dpif
> > *dpif)
> > return dpif_is_netdev(dpif);
> > }
> >
> > +bool
> > +dpif_may_support_psample(const struct dpif *dpif)
> > +{
> > + /* Userspace datapath does not support this action. */
> > + return !dpif_is_netdev(dpif);
> > +}
> > +
> > /* Meters */
> > void
> > dpif_meter_get_features(const struct dpif *dpif,
> > diff --git a/lib/dpif.h b/lib/dpif.h
> > index a764e8a59..6bef7d5b3 100644
> > --- a/lib/dpif.h
> > +++ b/lib/dpif.h
> > @@ -941,6 +941,7 @@ 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_may_support_explicit_drop_action(const struct dpif *);
> > +bool dpif_may_support_psample(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 4712d10a8..94c84d697 100644
> > --- a/ofproto/ofproto-dpif.c
> > +++ b/ofproto/ofproto-dpif.c
> > @@ -873,6 +873,12 @@ ovs_lb_output_action_supported(struct ofproto_dpif
> > *ofproto)
> > return ofproto->backer->rt_support.lb_output_action;
> > }
> >
> > +bool
> > +ovs_psample_supported(struct ofproto_dpif *ofproto)
> > +{
> > + return ofproto->backer->rt_support.psample;
> > +}
> > +
> > /* Tests whether 'backer''s datapath supports recirculation. Only newer
> > * datapaths support OVS_KEY_ATTR_RECIRC_ID in keys. We need to disable
> > some
> > * features on older datapaths that don't support this feature.
> > @@ -1609,6 +1615,42 @@ check_add_mpls(struct dpif_backer *backer)
> > return supported;
> > }
> >
> > +/* Tests whether 'backer''s datapath supports the OVS_ACTION_ATTR_PSAMPLE
> > + * action. */
> > +static bool
> > +check_psample(struct dpif_backer *backer)
> > +{
> > + uint8_t cookie[OVS_PSAMPLE_COOKIE_MAX_SIZE];
> > + struct odputil_keybuf keybuf;
> > + 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_init(&actions, 64);
> > +
> > + /* Generate a random max-size cookie. */
> > + random_bytes(cookie, sizeof(cookie));
>
> Don't parenthesize the argument of sizeof.
>
Ack.
> > +
> > + odp_put_psample_action(&actions, 10, cookie, sizeof cookie);
> > +
> > + supported = dpif_may_support_psample(backer->dpif) &&
> > + dpif_probe_feature(backer->dpif, "psample", &key, &actions, NULL);
>
> This function actually installs the flow into the kernel.
> You need to make sure that no packet can match it, e.g.
> by setting a bogus eth type as a match. Some existing
> probe functions require specific matches, some are just
> missing this part as well, but we should not blindly copy
> bad patterns.
>
I guess I was always thinking on a freshly started system but you're
right! If OVS is restarted, the installed flow can affect actual
traffic. I'll add a bogus key to make sure it's not problematic.
> > +
> > + ofpbuf_uninit(&actions);
> > + VLOG_INFO("%s: Datapath %s psample", dpif_name(backer->dpif),
>
> '%s: Datapath %s psample action' will be more clear.
>
Ack.
> > + supported ? "supports" : "does not support");
> > + return supported;
> > +}
> > +
> > #define CHECK_FEATURE__(NAME, SUPPORT, FIELD, VALUE, ETHTYPE)
> > \
> > static bool
> > \
> > check_##NAME(struct dpif_backer *backer)
> > \
> > @@ -1698,6 +1740,7 @@ check_support(struct dpif_backer *backer)
> > dpif_supports_lb_output_action(backer->dpif);
> > backer->rt_support.ct_zero_snat = dpif_supports_ct_zero_snat(backer);
> > backer->rt_support.add_mpls = check_add_mpls(backer);
> > + backer->rt_support.psample = check_psample(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 d33f73df8..bc7a19dab 100644
> > --- a/ofproto/ofproto-dpif.h
> > +++ b/ofproto/ofproto-dpif.h
> > @@ -213,7 +213,10 @@ struct group_dpif *group_dpif_lookup(struct
> > ofproto_dpif *,
> > DPIF_SUPPORT_FIELD(bool, ct_zero_snat, "Conntrack all-zero IP SNAT")
> > \
> >
> > \
> > /* True if the datapath supports add_mpls action. */
> > \
> > - DPIF_SUPPORT_FIELD(bool, add_mpls, "MPLS Label add")
> > + DPIF_SUPPORT_FIELD(bool, add_mpls, "MPLS Label add")
> > \
> > +
> > \
> > + /* True if the datapath supports psample action. */
> > \
> > + DPIF_SUPPORT_FIELD(bool, psample, "psample")
> >
> >
> > /* Stores the various features which the corresponding backer supports. */
> > @@ -412,4 +415,6 @@ bool ofproto_dpif_ct_zone_timeout_policy_get_name(
> >
> > bool ovs_explicit_drop_action_supported(struct ofproto_dpif *);
> >
> > +bool ovs_psample_supported(struct ofproto_dpif *);
> > +
> > #endif /* ofproto-dpif.h */
>
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