Subject: Re: [PATCH v2] Change in Openvswitch to support MPLS label depth of 3 in ingress direction

From: Martin Varghese <[email-masked]>
Date: Wed, 23 Oct 2019 10:34:59 +0530

On Tue, Oct 22, 2019 at 08:59:46PM -0700, Pravin Shelar wrote:
> On Tue, Oct 22, 2019 at 8:29 AM Martin Varghese
> <[email-masked]> wrote:
> >
> > On Tue, Oct 22, 2019 at 12:03:49AM -0700, Pravin Shelar wrote:
> > > On Sun, Oct 20, 2019 at 7:12 AM Martin Varghese
> > > <[email-masked]> wrote:
> > > >
> > > > From: Martin Varghese <[email-masked]>
> > > >
> > > > The openvswitch was supporting a MPLS label depth of 1 in the ingress
> > > > direction though the userspace OVS supports a max depth of 3 labels.
> > > > This change enables openvswitch module to support a max depth of
> > > > 3 labels in the ingress.
> > > >
> > > > Signed-off-by: Martin Varghese <[email-masked]>
> > > > ---
> > > > Changes in v2
> > > >    - Moved MPLS count validation from datapath to configuration.
> > > >    - Fixed set mpls function.
> > > >
> > > This patch looks pretty close now.
> > >
> > > >  net/openvswitch/actions.c      |  2 +-
> > > >  net/openvswitch/flow.c         | 20 ++++++++++-----
> > > >  net/openvswitch/flow.h         |  9 ++++---
> > > >  net/openvswitch/flow_netlink.c | 57 +++++++++++++++++++++++++++++++++---------
> > > >  4 files changed, 66 insertions(+), 22 deletions(-)
> > > >
> > > ...
> > > > diff --git a/net/openvswitch/flow_netlink.c b/net/openvswitch/flow_netlink.c
> > > > index d7559c6..21de061 100644
> > > > --- a/net/openvswitch/flow_netlink.c
> > > > +++ b/net/openvswitch/flow_netlink.c
> > > > @@ -424,7 +424,7 @@ size_t ovs_key_attr_size(void)
> > > >         [OVS_KEY_ATTR_DP_HASH]   = { .len = sizeof(u32) },
> > > >         [OVS_KEY_ATTR_TUNNEL]    = { .len = OVS_ATTR_NESTED,
> > > >                                      .next = ovs_tunnel_key_lens, },
> > > > -       [OVS_KEY_ATTR_MPLS]      = { .len = sizeof(struct ovs_key_mpls) },
> > > > +       [OVS_KEY_ATTR_MPLS]      = { .len = OVS_ATTR_VARIABLE },
> > > >         [OVS_KEY_ATTR_CT_STATE]  = { .len = sizeof(u32) },
> > > >         [OVS_KEY_ATTR_CT_ZONE]   = { .len = sizeof(u16) },
> > > >         [OVS_KEY_ATTR_CT_MARK]   = { .len = sizeof(u32) },
> > > > @@ -1628,10 +1628,25 @@ static int ovs_key_from_nlattrs(struct net *net, struct sw_flow_match *match,
> > > >
> > > >         if (attrs & (1 << OVS_KEY_ATTR_MPLS)) {
> > > >                 const struct ovs_key_mpls *mpls_key;
> > > > +               u32 hdr_len;
> > > > +               u32 label_count, label_count_mask, i;
> > > >
> > > >                 mpls_key = nla_data(a[OVS_KEY_ATTR_MPLS]);
> > > > -               SW_FLOW_KEY_PUT(match, mpls.top_lse,
> > > > -                               mpls_key->mpls_lse, is_mask);
> > > > +               hdr_len = nla_len(a[OVS_KEY_ATTR_MPLS]);
> > > > +               label_count = hdr_len / sizeof(struct ovs_key_mpls);
> > > > +
> > > > +               if (label_count == 0 || label_count > MPLS_LABEL_DEPTH ||
> > > > +                   hdr_len % sizeof(struct ovs_key_mpls))
> > > > +                       return -EINVAL;
> > > > +
> > > > +               label_count_mask =  GENMASK(label_count - 1, 0);
> > > > +
> > > > +               for (i = 0 ; i < label_count; i++)
> > > > +                       SW_FLOW_KEY_PUT(match, mpls.lse[i],
> > > > +                                       mpls_key[i].mpls_lse, is_mask);
> > > > +
> > > > +               SW_FLOW_KEY_PUT(match, mpls.num_labels_mask,
> > > > +                               label_count_mask, is_mask);
> > > >
> > > >                 attrs &= ~(1 << OVS_KEY_ATTR_MPLS);
> > > >          }
> > > > @@ -2114,13 +2129,18 @@ static int __ovs_nla_put_key(const struct sw_flow_key *swkey,
> > > >                 ether_addr_copy(arp_key->arp_sha, output->ipv4.arp.sha);
> > > >                 ether_addr_copy(arp_key->arp_tha, output->ipv4.arp.tha);
> > > >         } else if (eth_p_mpls(swkey->eth.type)) {
> > > > +               u8 i, num_labels;
> > > >                 struct ovs_key_mpls *mpls_key;
> > > >
> > > > -               nla = nla_reserve(skb, OVS_KEY_ATTR_MPLS, sizeof(*mpls_key));
> > > > +               num_labels = hweight_long(output->mpls.num_labels_mask);
> > > > +               nla = nla_reserve(skb, OVS_KEY_ATTR_MPLS,
> > > > +                                 num_labels * sizeof(*mpls_key));
> > > >                 if (!nla)
> > > >                         goto nla_put_failure;
> > > > +
> > > >                 mpls_key = nla_data(nla);
> > > > -               mpls_key->mpls_lse = output->mpls.top_lse;
> > > > +               for (i = 0; i < num_labels; i++)
> > > > +                       mpls_key[i].mpls_lse = output->mpls.lse[i];
> > > >         }
> > > >
> > > >         if ((swkey->eth.type == htons(ETH_P_IP) ||
> > > > @@ -2957,6 +2977,10 @@ static int __ovs_nla_copy_actions(struct net *net, const struct nlattr *attr,
> > > >         u8 mac_proto = ovs_key_mac_proto(key);
> > > >         const struct nlattr *a;
> > > >         int rem, err;
> > > > +       u32 mpls_label_count = 0;
> > > > +
> > > > +       if (eth_p_mpls(eth_type))
> > > > +               mpls_label_count = hweight_long(key->mpls.num_labels_mask);
> > > >
> > > The MPLS push and pop action could be part of nested actions in
> > > sample, so the count needs to be global count across such nested
> > > actions. have a look at validate_and_copy_sample().
> > >
> > Embedding mpls_label_count in struct sw_flow_actions will not work for clone
> >
> > I guess we need to move the below code to ovs_nla_copy_actions and extend the  arguments of __ovs_nla_copy_actions to take mpls_label_count also
> > if (eth_p_mpls(eth_type))
> >                 mpls_label_count = hweight_long(key->mpls.num_labels_mask)
> >
> >
> I am not suggesting changing sw_flow_actions, You can define count
> variable in ovs_nla_copy_actions() and pass it as a pointer to nested
> function. That can be used to keep track of MPLS labels at all nested
> actions.

Actions clone & sample does a clone of SKB correct?
Hence shouldn't they maintain a seperate mpls_label count for each nested action set
I assume instead of passing as pointer from ovs_nla_copy_actions ,if passed by value it should 
solve the problem.Need to try that though.