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ovn-northd: Document OVS register usage in logical flows.
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Also, use macros instead of bare references to register names.

Acked-by: Han Zhou <hzhou@ovn.org>
Signed-off-by: Dumitru Ceara <dceara@redhat.com>
Signed-off-by: Numan Siddique <numans@ovn.org>
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@dceara @numansiddique
dceara authored and numansiddique committed Jul 6, 2020
1 parent 78ec956 commit 47149a6
Showing 1 changed file with 113 additions and 48 deletions.
161 changes: 113 additions & 48 deletions northd/ovn-northd.c
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Expand Up @@ -227,8 +227,58 @@ enum ovn_stage {
#define REG_ECMP_GROUP_ID "reg8[0..15]"
#define REG_ECMP_MEMBER_ID "reg8[16..31]"

/* Registers used for routing. */
#define REG_NEXT_HOP_IPV4 "reg0"
#define REG_NEXT_HOP_IPV6 "xxreg0"
#define REG_SRC_IPV4 "reg1"
#define REG_SRC_IPV6 "xxreg1"

#define FLAGBIT_NOT_VXLAN "flags[1] == 0"

/*
* OVS register usage:
*
* Logical Switch pipeline:
* +---------+-------------------------------------+
* | R0 | REGBIT_{CONNTRACK/DHCP/DNS/HAIRPIN} |
* +---------+-------------------------------------+
* | R1 - R9 | UNUSED |
* +---------+-------------------------------------+
*
* Logical Router pipeline:
* +-----+--------------------------+---+---------------+
* | R0 | REGBIT_ND_RA_OPTS_RESULT | | |
* | | (= IN_ND_RA_OPTIONS) | | |
* | | NEXT_HOP_IPV4 | X | |
* | | (>= IP_INPUT) | X | |
* +-----+--------------------------+ R | |
* | R1 | SRC_IPV4 for ARP-REQ | E | NEXT_HOP_IPV6 |
* | | (>= IP_INPUT) | G | (>= IP_INPUT) |
* +-----+--------------------------+ 0 | |
* | R2 | UNUSED | | |
* +-----+--------------------------+ | |
* | R3 | UNUSED | | |
* +-----+--------------------------+---+---------------+
* | R4 | UNUSED | | |
* +-----+--------------------------+ X | |
* | R5 | UNUSED | X |SRC_IPV6 for NS|
* +-----+--------------------------+ R | (>= IP_INPUT) |
* | R6 | UNUSED | E | |
* +-----+--------------------------+ G | |
* | R7 | UNUSED | 1 | |
* +-----+--------------------------+---+---------------+
* | R8 | ECMP_GROUP_ID |
* | | ECMP_MEMBER_ID |
* +-----+--------------------------+
* | | REGBIT_{ |
* | | EGRESS_LOOPBACK/ |
* | R9 | PKT_LARGER/ |
* | | LOOKUP_NEIGHBOR_RESULT/|
* | | SKIP_LOOKUP_NEIGHBOR} |
* +-----+--------------------------+
*
*/

/* Returns an "enum ovn_stage" built from the arguments. */
static enum ovn_stage
ovn_stage_build(enum ovn_datapath_type dp_type, enum ovn_pipeline pipeline,
Expand Down Expand Up @@ -7139,15 +7189,15 @@ build_routing_policy_flow(struct hmap *lflows, struct ovn_datapath *od,
ds_put_format(&actions, "pkt.mark = %u; ", pkt_mark);
}
bool is_ipv4 = strchr(rule->nexthop, '.') ? true : false;
ds_put_format(&actions, "%sreg0 = %s; "
"%sreg1 = %s; "
ds_put_format(&actions, "%s = %s; "
"%s = %s; "
"eth.src = %s; "
"outport = %s; "
"flags.loopback = 1; "
"next;",
is_ipv4 ? "" : "xx",
is_ipv4 ? REG_NEXT_HOP_IPV4 : REG_NEXT_HOP_IPV6,
rule->nexthop,
is_ipv4 ? "" : "xx",
is_ipv4 ? REG_SRC_IPV4 : REG_SRC_IPV6,
lrp_addr_s,
out_port->lrp_networks.ea_s,
out_port->json_key);
Expand Down Expand Up @@ -7537,14 +7587,14 @@ build_ecmp_route_flow(struct hmap *lflows, struct ovn_datapath *od,
REG_ECMP_MEMBER_ID" == %"PRIu16,
eg->id, er->id);
ds_clear(&actions);
ds_put_format(&actions, "%sreg0 = %s; "
"%sreg1 = %s; "
ds_put_format(&actions, "%s = %s; "
"%s = %s; "
"eth.src = %s; "
"outport = %s; "
"next;",
is_ipv4 ? "" : "xx",
is_ipv4 ? REG_NEXT_HOP_IPV4 : REG_NEXT_HOP_IPV6,
route->nexthop,
is_ipv4 ? "" : "xx",
is_ipv4 ? REG_SRC_IPV4 : REG_SRC_IPV6,
lrp_addr_s,
out_port->lrp_networks.ea_s,
out_port->json_key);
Expand Down Expand Up @@ -7579,21 +7629,21 @@ add_route(struct hmap *lflows, const struct ovn_port *op,
&match, &priority);

struct ds actions = DS_EMPTY_INITIALIZER;
ds_put_format(&actions, "ip.ttl--; "REG_ECMP_GROUP_ID" = 0; %sreg0 = ",
is_ipv4 ? "" : "xx");
ds_put_format(&actions, "ip.ttl--; "REG_ECMP_GROUP_ID" = 0; %s = ",
is_ipv4 ? REG_NEXT_HOP_IPV4 : REG_NEXT_HOP_IPV6);

if (gateway) {
ds_put_cstr(&actions, gateway);
} else {
ds_put_format(&actions, "ip%s.dst", is_ipv4 ? "4" : "6");
}
ds_put_format(&actions, "; "
"%sreg1 = %s; "
"%s = %s; "
"eth.src = %s; "
"outport = %s; "
"flags.loopback = 1; "
"next;",
is_ipv4 ? "" : "xx",
is_ipv4 ? REG_SRC_IPV4 : REG_SRC_IPV6,
lrp_addr_s,
op->lrp_networks.ea_s,
op->json_key);
Expand Down Expand Up @@ -9064,7 +9114,8 @@ build_lrouter_flows(struct hmap *datapaths, struct hmap *ports,
ds_put_format(
&match, "outport == %s && %s == %s",
od->l3dgw_port->json_key,
is_v6 ? "xxreg0" : "reg0", nat->external_ip);
is_v6 ? REG_NEXT_HOP_IPV6 : REG_NEXT_HOP_IPV4,
nat->external_ip);
ds_clear(&actions);
ds_put_format(
&actions, "eth.dst = %s; next;",
Expand Down Expand Up @@ -9226,9 +9277,10 @@ build_lrouter_flows(struct hmap *datapaths, struct hmap *ports,
* router, add flows that are specific to a NAT rule. These
* flows indicate the presence of an applicable NAT rule that
* can be applied in a distributed manner.
* In particulr reg1 and eth.src are set to NAT external IP and
* NAT external mac so the ARP request generated in the following
* stage is sent out with proper IP/MAC src addresses
* In particulr REG_SRC_IPV4/REG_SRC_IPV6 and eth.src are set to
* NAT external IP and NAT external mac so the ARP request
* generated in the following stage is sent out with proper IP/MAC
* src addresses.
*/
if (distributed) {
ds_clear(&match);
Expand All @@ -9238,8 +9290,9 @@ build_lrouter_flows(struct hmap *datapaths, struct hmap *ports,
"is_chassis_resident(\"%s\")",
is_v6 ? "6" : "4", nat->logical_ip,
od->l3dgw_port->json_key, nat->logical_port);
ds_put_format(&actions, "eth.src = %s; %sreg1 = %s; next;",
nat->external_mac, is_v6 ? "xx" : "",
ds_put_format(&actions, "eth.src = %s; %s = %s; next;",
nat->external_mac,
is_v6 ? REG_SRC_IPV6 : REG_SRC_IPV4,
nat->external_ip);
ovn_lflow_add_with_hint(lflows, od, S_ROUTER_IN_GW_REDIRECT,
100, ds_cstr(&match),
Expand Down Expand Up @@ -9561,14 +9614,15 @@ build_lrouter_flows(struct hmap *datapaths, struct hmap *ports,
*
* For regular routes without ECMP, table IP_ROUTING sets outport to the
* correct output port, eth.src to the output port's MAC address, and
* '[xx]reg0' to the next-hop IP address (leaving 'ip[46].dst', the
* packet’s final destination, unchanged), and advances to the next table.
* REG_NEXT_HOP_IPV4/REG_NEXT_HOP_IPV6 to the next-hop IP address
* (leaving 'ip[46].dst', the packet’s final destination, unchanged), and
* advances to the next table.
*
* For ECMP routes, i.e. multiple routes with same policy and prefix, table
* IP_ROUTING remembers ECMP group id and selects a member id, and advances
* to table IP_ROUTING_ECMP, which sets outport, eth.src and '[xx]reg0' for
* the selected ECMP member.
* */
* to table IP_ROUTING_ECMP, which sets outport, eth.src and
* REG_NEXT_HOP_IPV4/REG_NEXT_HOP_IPV6 for the selected ECMP member.
*/
HMAP_FOR_EACH (op, key_node, ports) {
if (!op->nbrp) {
continue;
Expand Down Expand Up @@ -9705,8 +9759,8 @@ build_lrouter_flows(struct hmap *datapaths, struct hmap *ports,
* permitted/denied/rerouted to the address in the rule's nexthop.
* This table sets outport to the correct out_port,
* eth.src to the output port's MAC address,
* and '[xx]reg0' to the next-hop IP address (leaving
* 'ip[46].dst', the packet’s final destination, unchanged), and
* and REG_NEXT_HOP_IPV4/REG_NEXT_HOP_IPV6 to the next-hop IP address
* (leaving 'ip[46].dst', the packet’s final destination, unchanged), and
* advances to the next table for ARP/ND resolution. */
HMAP_FOR_EACH (od, key_node, datapaths) {
if (!od->nbr) {
Expand Down Expand Up @@ -9743,9 +9797,11 @@ build_lrouter_flows(struct hmap *datapaths, struct hmap *ports,
/* Local router ingress table ARP_RESOLVE: ARP Resolution.
*
* Any unicast packet that reaches this table is an IP packet whose
* next-hop IP address is in reg0. (ip4.dst is the final destination.)
* This table resolves the IP address in reg0 into an output port in
* outport and an Ethernet address in eth.dst.
* next-hop IP address is in REG_NEXT_HOP_IPV4/REG_NEXT_HOP_IPV6
* (ip4.dst/ipv6.dst is the final destination).
* This table resolves the IP address in
* REG_NEXT_HOP_IPV4/REG_NEXT_HOP_IPV6 into an output port in outport and
* an Ethernet address in eth.dst.
*/
HMAP_FOR_EACH (op, key_node, ports) {
if (op->nbsp && !lsp_is_enabled(op->nbsp)) {
Expand All @@ -9754,17 +9810,18 @@ build_lrouter_flows(struct hmap *datapaths, struct hmap *ports,

if (op->nbrp) {
/* This is a logical router port. If next-hop IP address in
* '[xx]reg0' matches IP address of this router port, then
* the packet is intended to eventually be sent to this
* logical port. Set the destination mac address using this
* port's mac address.
* REG_NEXT_HOP_IPV4/REG_NEXT_HOP_IPV6 matches IP address of this
* router port, then the packet is intended to eventually be sent
* to this logical port. Set the destination mac address using
* this port's mac address.
*
* The packet is still in peer's logical pipeline. So the match
* should be on peer's outport. */
if (op->peer && op->nbrp->peer) {
if (op->lrp_networks.n_ipv4_addrs) {
ds_clear(&match);
ds_put_format(&match, "outport == %s && reg0 == ",
ds_put_format(&match, "outport == %s && "
REG_NEXT_HOP_IPV4 "== ",
op->peer->json_key);
op_put_v4_networks(&match, op, false);

Expand All @@ -9779,7 +9836,8 @@ build_lrouter_flows(struct hmap *datapaths, struct hmap *ports,

if (op->lrp_networks.n_ipv6_addrs) {
ds_clear(&match);
ds_put_format(&match, "outport == %s && xxreg0 == ",
ds_put_format(&match, "outport == %s && "
REG_NEXT_HOP_IPV6 " == ",
op->peer->json_key);
op_put_v6_networks(&match, op);

Expand Down Expand Up @@ -9850,7 +9908,8 @@ build_lrouter_flows(struct hmap *datapaths, struct hmap *ports,
}

ds_clear(&match);
ds_put_format(&match, "outport == %s && reg0 == %s",
ds_put_format(&match, "outport == %s && "
REG_NEXT_HOP_IPV4 " == %s",
peer->json_key, ip_s);

ds_clear(&actions);
Expand Down Expand Up @@ -9886,7 +9945,8 @@ build_lrouter_flows(struct hmap *datapaths, struct hmap *ports,
}

ds_clear(&match);
ds_put_format(&match, "outport == %s && xxreg0 == %s",
ds_put_format(&match, "outport == %s && "
REG_NEXT_HOP_IPV6 " == %s",
peer->json_key, ip_s);

ds_clear(&actions);
Expand Down Expand Up @@ -9937,8 +9997,9 @@ build_lrouter_flows(struct hmap *datapaths, struct hmap *ports,

if (find_lrp_member_ip(peer, vip)) {
ds_clear(&match);
ds_put_format(&match, "outport == %s && reg0 == %s",
peer->json_key, vip);
ds_put_format(&match, "outport == %s && "
REG_NEXT_HOP_IPV4 " == %s",
peer->json_key, vip);

ds_clear(&actions);
ds_put_format(&actions,
Expand Down Expand Up @@ -9983,8 +10044,9 @@ build_lrouter_flows(struct hmap *datapaths, struct hmap *ports,
}

ds_clear(&match);
ds_put_format(&match, "outport == %s && reg0 == %s",
peer->json_key, vip);
ds_put_format(&match, "outport == %s && "
REG_NEXT_HOP_IPV4 " == %s",
peer->json_key, vip);

ds_clear(&actions);
ds_put_format(&actions, "eth.dst = %s; next;", ea_s);
Expand Down Expand Up @@ -10038,7 +10100,8 @@ build_lrouter_flows(struct hmap *datapaths, struct hmap *ports,

if (router_port->lrp_networks.n_ipv4_addrs) {
ds_clear(&match);
ds_put_format(&match, "outport == %s && reg0 == ",
ds_put_format(&match, "outport == %s && "
REG_NEXT_HOP_IPV4 " == ",
peer->json_key);
op_put_v4_networks(&match, router_port, false);

Expand All @@ -10053,7 +10116,8 @@ build_lrouter_flows(struct hmap *datapaths, struct hmap *ports,

if (router_port->lrp_networks.n_ipv6_addrs) {
ds_clear(&match);
ds_put_format(&match, "outport == %s && xxreg0 == ",
ds_put_format(&match, "outport == %s && "
REG_NEXT_HOP_IPV6 " == ",
peer->json_key);
op_put_v6_networks(&match, router_port);

Expand All @@ -10075,10 +10139,10 @@ build_lrouter_flows(struct hmap *datapaths, struct hmap *ports,
}

ovn_lflow_add(lflows, od, S_ROUTER_IN_ARP_RESOLVE, 0, "ip4",
"get_arp(outport, reg0); next;");
"get_arp(outport, " REG_NEXT_HOP_IPV4 "); next;");

ovn_lflow_add(lflows, od, S_ROUTER_IN_ARP_RESOLVE, 0, "ip6",
"get_nd(outport, xxreg0); next;");
"get_nd(outport, " REG_NEXT_HOP_IPV6 "); next;");
}

/* Local router ingress table CHK_PKT_LEN: Check packet length.
Expand Down Expand Up @@ -10224,7 +10288,8 @@ build_lrouter_flows(struct hmap *datapaths, struct hmap *ports,

ds_clear(&match);
ds_put_format(&match, "eth.dst == 00:00:00:00:00:00 && "
"ip6 && xxreg0 == %s", route->nexthop);
"ip6 && " REG_NEXT_HOP_IPV6 " == %s",
route->nexthop);
struct in6_addr sn_addr;
struct eth_addr eth_dst;
in6_addr_solicited_node(&sn_addr, &gw_ip6);
Expand Down Expand Up @@ -10252,15 +10317,15 @@ build_lrouter_flows(struct hmap *datapaths, struct hmap *ports,
"eth.dst == 00:00:00:00:00:00 && ip4",
"arp { "
"eth.dst = ff:ff:ff:ff:ff:ff; "
"arp.spa = reg1; "
"arp.tpa = reg0; "
"arp.spa = " REG_SRC_IPV4 "; "
"arp.tpa = " REG_NEXT_HOP_IPV4 "; "
"arp.op = 1; " /* ARP request */
"output; "
"};");
ovn_lflow_add(lflows, od, S_ROUTER_IN_ARP_REQUEST, 100,
"eth.dst == 00:00:00:00:00:00 && ip6",
"nd_ns { "
"nd.target = xxreg0; "
"nd.target = " REG_NEXT_HOP_IPV6 "; "
"output; "
"};");
ovn_lflow_add(lflows, od, S_ROUTER_IN_ARP_REQUEST, 0, "1", "output;");
Expand Down

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