/*
- * Copyright (c) 2009, 2010, 2011, 2012 Nicira, Inc.
+ * Copyright (c) 2009, 2010, 2011, 2012, 2013 Nicira, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
/* Flow classifier.
*
- * A classifier is a "struct classifier",
- * a hash map from a set of wildcards to a "struct cls_table",
- * a hash map from fixed field values to "struct cls_rule",
- * which can contain a list of otherwise identical rules
- * with lower priorities.
- */
+ *
+ * What?
+ * =====
+ *
+ * A flow classifier holds any number of "rules", each of which specifies
+ * values to match for some fields or subfields and a priority. Each OpenFlow
+ * table is implemented as a flow classifier.
+ *
+ * The classifier has two primary design goals. The first is obvious: given a
+ * set of packet headers, as quickly as possible find the highest-priority rule
+ * that matches those headers. The following section describes the second
+ * goal.
+ *
+ *
+ * "Un-wildcarding"
+ * ================
+ *
+ * A primary goal of the flow classifier is to produce, as a side effect of a
+ * packet lookup, a wildcard mask that indicates which bits of the packet
+ * headers were essential to the classification result. Ideally, a 1-bit in
+ * any position of this mask means that, if the corresponding bit in the packet
+ * header were flipped, then the classification result might change. A 0-bit
+ * means that changing the packet header bit would have no effect. Thus, the
+ * wildcarded bits are the ones that played no role in the classification
+ * decision.
+ *
+ * Such a wildcard mask is useful with datapaths that support installing flows
+ * that wildcard fields or subfields. If an OpenFlow lookup for a TCP flow
+ * does not actually look at the TCP source or destination ports, for example,
+ * then the switch may install into the datapath a flow that wildcards the port
+ * numbers, which in turn allows the datapath to handle packets that arrive for
+ * other TCP source or destination ports without additional help from
+ * ovs-vswitchd. This is useful for the Open vSwitch software and,
+ * potentially, for ASIC-based switches as well.
+ *
+ * Some properties of the wildcard mask:
+ *
+ * - "False 1-bits" are acceptable, that is, setting a bit in the wildcard
+ * mask to 1 will never cause a packet to be forwarded the wrong way.
+ * As a corollary, a wildcard mask composed of all 1-bits will always
+ * yield correct (but often needlessly inefficient) behavior.
+ *
+ * - "False 0-bits" can cause problems, so they must be avoided. In the
+ * extreme case, a mask of all 0-bits is only correct if the classifier
+ * contains only a single flow that matches all packets.
+ *
+ * - 0-bits are desirable because they allow the datapath to act more
+ * autonomously, relying less on ovs-vswitchd to process flow setups,
+ * thereby improving performance.
+ *
+ * - We don't know a good way to generate wildcard masks with the maximum
+ * (correct) number of 0-bits. We use various approximations, described
+ * in later sections.
+ *
+ * - Wildcard masks for lookups in a given classifier yield a
+ * non-overlapping set of rules. More specifically:
+ *
+ * Consider an classifier C1 filled with an arbitrary collection of rules
+ * and an empty classifier C2. Now take a set of packet headers H and
+ * look it up in C1, yielding a highest-priority matching rule R1 and
+ * wildcard mask M. Form a new classifier rule R2 out of packet headers
+ * H and mask M, and add R2 to C2 with a fixed priority. If one were to
+ * do this for every possible set of packet headers H, then this
+ * process would not attempt to add any overlapping rules to C2, that is,
+ * any packet lookup using the rules generated by this process matches at
+ * most one rule in C2.
+ *
+ * During the lookup process, the classifier starts out with a wildcard mask
+ * that is all 0-bits, that is, fully wildcarded. As lookup proceeds, each
+ * step tends to add constraints to the wildcard mask, that is, change
+ * wildcarded 0-bits into exact-match 1-bits. We call this "un-wildcarding".
+ * A lookup step that examines a particular field must un-wildcard that field.
+ * In general, un-wildcarding is necessary for correctness but undesirable for
+ * performance.
+ *
+ *
+ * Basic Classifier Design
+ * =======================
+ *
+ * Suppose that all the rules in a classifier had the same form. For example,
+ * suppose that they all matched on the source and destination Ethernet address
+ * and wildcarded all the other fields. Then the obvious way to implement a
+ * classifier would be a hash table on the source and destination Ethernet
+ * addresses. If new classification rules came along with a different form,
+ * you could add a second hash table that hashed on the fields matched in those
+ * rules. With two hash tables, you look up a given flow in each hash table.
+ * If there are no matches, the classifier didn't contain a match; if you find
+ * a match in one of them, that's the result; if you find a match in both of
+ * them, then the result is the rule with the higher priority.
+ *
+ * This is how the classifier works. In a "struct classifier", each form of
+ * "struct cls_rule" present (based on its ->match.mask) goes into a separate
+ * "struct cls_subtable". A lookup does a hash lookup in every "struct
+ * cls_subtable" in the classifier and tracks the highest-priority match that
+ * it finds. The subtables are kept in a descending priority order according
+ * to the highest priority rule in each subtable, which allows lookup to skip
+ * over subtables that can't possibly have a higher-priority match than already
+ * found. Eliminating lookups through priority ordering aids both classifier
+ * primary design goals: skipping lookups saves time and avoids un-wildcarding
+ * fields that those lookups would have examined.
+ *
+ * One detail: a classifier can contain multiple rules that are identical other
+ * than their priority. When this happens, only the highest priority rule out
+ * of a group of otherwise identical rules is stored directly in the "struct
+ * cls_subtable", with the other almost-identical rules chained off a linked
+ * list inside that highest-priority rule.
+ *
+ *
+ * Staged Lookup (Wildcard Optimization)
+ * =====================================
+ *
+ * Subtable lookup is performed in ranges defined for struct flow, starting
+ * from metadata (registers, in_port, etc.), then L2 header, L3, and finally
+ * L4 ports. Whenever it is found that there are no matches in the current
+ * subtable, the rest of the subtable can be skipped.
+ *
+ * Staged lookup does not reduce lookup time, and it may increase it, because
+ * it changes a single hash table lookup into multiple hash table lookups.
+ * It reduces un-wildcarding significantly in important use cases.
+ *
+ *
+ * Prefix Tracking (Wildcard Optimization)
+ * =======================================
+ *
+ * Classifier uses prefix trees ("tries") for tracking the used
+ * address space, enabling skipping classifier tables containing
+ * longer masks than necessary for the given address. This reduces
+ * un-wildcarding for datapath flows in parts of the address space
+ * without host routes, but consulting extra data structures (the
+ * tries) may slightly increase lookup time.
+ *
+ * Trie lookup is interwoven with staged lookup, so that a trie is
+ * searched only when the configured trie field becomes relevant for
+ * the lookup. The trie lookup results are retained so that each trie
+ * is checked at most once for each classifier lookup.
+ *
+ * This implementation tracks the number of rules at each address
+ * prefix for the whole classifier. More aggressive table skipping
+ * would be possible by maintaining lists of tables that have prefixes
+ * at the lengths encountered on tree traversal, or by maintaining
+ * separate tries for subsets of rules separated by metadata fields.
+ *
+ * Prefix tracking is configured via OVSDB "Flow_Table" table,
+ * "fieldspec" column. "fieldspec" is a string map where a "prefix"
+ * key tells which fields should be used for prefix tracking. The
+ * value of the "prefix" key is a comma separated list of field names.
+ *
+ * There is a maximum number of fields that can be enabled for any one
+ * flow table. Currently this limit is 3.
+ *
+ *
+ * Partitioning (Lookup Time and Wildcard Optimization)
+ * ====================================================
+ *
+ * Suppose that a given classifier is being used to handle multiple stages in a
+ * pipeline using "resubmit", with metadata (that is, the OpenFlow 1.1+ field
+ * named "metadata") distinguishing between the different stages. For example,
+ * metadata value 1 might identify ingress rules, metadata value 2 might
+ * identify ACLs, and metadata value 3 might identify egress rules. Such a
+ * classifier is essentially partitioned into multiple sub-classifiers on the
+ * basis of the metadata value.
+ *
+ * The classifier has a special optimization to speed up matching in this
+ * scenario:
+ *
+ * - Each cls_subtable that matches on metadata gets a tag derived from the
+ * subtable's mask, so that it is likely that each subtable has a unique
+ * tag. (Duplicate tags have a performance cost but do not affect
+ * correctness.)
+ *
+ * - For each metadata value matched by any cls_rule, the classifier
+ * constructs a "struct cls_partition" indexed by the metadata value.
+ * The cls_partition has a 'tags' member whose value is the bitwise-OR of
+ * the tags of each cls_subtable that contains any rule that matches on
+ * the cls_partition's metadata value. In other words, struct
+ * cls_partition associates metadata values with subtables that need to
+ * be checked with flows with that specific metadata value.
+ *
+ * Thus, a flow lookup can start by looking up the partition associated with
+ * the flow's metadata, and then skip over any cls_subtable whose 'tag' does
+ * not intersect the partition's 'tags'. (The flow must also be looked up in
+ * any cls_subtable that doesn't match on metadata. We handle that by giving
+ * any such cls_subtable TAG_ALL as its 'tags' so that it matches any tag.)
+ *
+ * Partitioning saves lookup time by reducing the number of subtable lookups.
+ * Each eliminated subtable lookup also reduces the amount of un-wildcarding.
+ *
+ *
+ * Thread-safety
+ * =============
+ *
+ * The classifier may safely be accessed by many reader threads concurrently or
+ * by a single writer. */
+#include "fat-rwlock.h"
#include "flow.h"
+#include "hindex.h"
#include "hmap.h"
#include "list.h"
+#include "match.h"
+#include "meta-flow.h"
+#include "tag.h"
#include "openflow/nicira-ext.h"
#include "openflow/openflow.h"
+#include "ovs-thread.h"
+#include "util.h"
#ifdef __cplusplus
extern "C" {
#endif
+/* Needed only for the lock annotation in struct classifier. */
+extern struct ovs_mutex ofproto_mutex;
+
+/* Classifier internal data structures. */
+struct cls_classifier;
+struct cls_subtable;
+struct cls_partition;
+
/* A flow classifier. */
struct classifier {
- int n_rules; /* Total number of rules. */
- struct hmap tables; /* Contains "struct cls_table"s. */
+ struct fat_rwlock rwlock OVS_ACQ_AFTER(ofproto_mutex);
+ struct cls_classifier *cls;
};
-/* A set of rules that all have the same fields wildcarded. */
-struct cls_table {
- struct hmap_node hmap_node; /* Within struct classifier 'tables' hmap. */
- struct hmap rules; /* Contains "struct cls_rule"s. */
- struct flow_wildcards wc; /* Wildcards for fields. */
- int n_table_rules; /* Number of rules, including duplicates. */
- bool is_catchall; /* True if this table wildcards every field. */
+enum {
+ CLS_MAX_INDICES = 3, /* Maximum number of lookup indices per subtable. */
+ CLS_MAX_TRIES = 3 /* Maximum number of prefix trees per classifier. */
};
-/* Returns true if 'table' is a "catch-all" table that will match every
- * packet (if there is no higher-priority match). */
-static inline bool
-cls_table_is_catchall(const struct cls_table *table)
-{
- return table->is_catchall;
-}
-
-/* A flow classification rule.
- *
- * Use one of the cls_rule_*() functions to initialize a cls_rule.
- *
- * The cls_rule_*() functions below maintain the following important
- * invariant that the classifier depends on:
- *
- * - If a bit or a field is wildcarded in 'wc', then the corresponding bit or
- * field in 'flow' is set to all-0-bits. (The
- * cls_rule_zero_wildcarded_fields() function can be used to restore this
- * invariant after adding wildcards.)
- */
+/* A rule in a "struct cls_subtable". */
struct cls_rule {
- struct hmap_node hmap_node; /* Within struct cls_table 'rules'. */
+ struct hmap_node hmap_node; /* Within struct cls_subtable 'rules'. */
struct list list; /* List of identical, lower-priority rules. */
- struct flow flow; /* All field values. */
- struct flow_wildcards wc; /* Wildcards for fields. */
+ struct minimatch match; /* Matching rule. */
unsigned int priority; /* Larger numbers are higher priorities. */
+ struct cls_partition *partition;
+ struct hindex_node index_nodes[CLS_MAX_INDICES]; /* Within subtable's
+ * 'indices'. */
};
-void cls_rule_init(const struct flow *, const struct flow_wildcards *,
- unsigned int priority, struct cls_rule *);
-void cls_rule_init_exact(const struct flow *, unsigned int priority,
- struct cls_rule *);
-void cls_rule_init_catchall(struct cls_rule *, unsigned int priority);
-
-void cls_rule_zero_wildcarded_fields(struct cls_rule *);
-
-bool cls_rule_is_loose_match(const struct cls_rule *rule,
- const struct cls_rule *criteria);
-
-void cls_rule_set_reg(struct cls_rule *, unsigned int reg_idx, uint32_t value);
-void cls_rule_set_reg_masked(struct cls_rule *, unsigned int reg_idx,
- uint32_t value, uint32_t mask);
-void cls_rule_set_metadata(struct cls_rule *, ovs_be64 metadata);
-void cls_rule_set_metadata_masked(struct cls_rule *, ovs_be64 metadata,
- ovs_be64 mask);
-void cls_rule_set_tun_id(struct cls_rule *, ovs_be64 tun_id);
-void cls_rule_set_tun_id_masked(struct cls_rule *,
- ovs_be64 tun_id, ovs_be64 mask);
-void cls_rule_set_in_port(struct cls_rule *, uint16_t ofp_port);
-void cls_rule_set_dl_type(struct cls_rule *, ovs_be16);
-void cls_rule_set_dl_src(struct cls_rule *, const uint8_t[6]);
-void cls_rule_set_dl_src_masked(struct cls_rule *, const uint8_t dl_src[6],
- const uint8_t mask[6]);
-void cls_rule_set_dl_dst(struct cls_rule *, const uint8_t[6]);
-void cls_rule_set_dl_dst_masked(struct cls_rule *, const uint8_t dl_dst[6],
- const uint8_t mask[6]);
-void cls_rule_set_dl_tci(struct cls_rule *, ovs_be16 tci);
-void cls_rule_set_dl_tci_masked(struct cls_rule *,
- ovs_be16 tci, ovs_be16 mask);
-void cls_rule_set_any_vid(struct cls_rule *);
-void cls_rule_set_dl_vlan(struct cls_rule *, ovs_be16);
-void cls_rule_set_any_pcp(struct cls_rule *);
-void cls_rule_set_dl_vlan_pcp(struct cls_rule *, uint8_t);
-void cls_rule_set_tp_src(struct cls_rule *, ovs_be16);
-void cls_rule_set_tp_src_masked(struct cls_rule *,
- ovs_be16 port, ovs_be16 mask);
-void cls_rule_set_tp_dst(struct cls_rule *, ovs_be16);
-void cls_rule_set_tp_dst_masked(struct cls_rule *,
- ovs_be16 port, ovs_be16 mask);
-void cls_rule_set_nw_proto(struct cls_rule *, uint8_t);
-void cls_rule_set_nw_src(struct cls_rule *, ovs_be32);
-void cls_rule_set_nw_src_masked(struct cls_rule *, ovs_be32 ip, ovs_be32 mask);
-void cls_rule_set_nw_dst(struct cls_rule *, ovs_be32);
-void cls_rule_set_nw_dst_masked(struct cls_rule *, ovs_be32 ip, ovs_be32 mask);
-void cls_rule_set_nw_dscp(struct cls_rule *, uint8_t);
-void cls_rule_set_nw_ecn(struct cls_rule *, uint8_t);
-void cls_rule_set_nw_ttl(struct cls_rule *, uint8_t);
-void cls_rule_set_nw_frag(struct cls_rule *, uint8_t nw_frag);
-void cls_rule_set_nw_frag_masked(struct cls_rule *,
- uint8_t nw_frag, uint8_t mask);
-void cls_rule_set_icmp_type(struct cls_rule *, uint8_t);
-void cls_rule_set_icmp_code(struct cls_rule *, uint8_t);
-void cls_rule_set_arp_sha(struct cls_rule *, const uint8_t[6]);
-void cls_rule_set_arp_tha(struct cls_rule *, const uint8_t[6]);
-void cls_rule_set_ipv6_src(struct cls_rule *, const struct in6_addr *);
-void cls_rule_set_ipv6_src_masked(struct cls_rule *, const struct in6_addr *,
- const struct in6_addr *);
-void cls_rule_set_ipv6_dst(struct cls_rule *, const struct in6_addr *);
-void cls_rule_set_ipv6_dst_masked(struct cls_rule *, const struct in6_addr *,
- const struct in6_addr *);
-void cls_rule_set_ipv6_label(struct cls_rule *, ovs_be32);
-void cls_rule_set_nd_target(struct cls_rule *, const struct in6_addr *);
-void cls_rule_set_nd_target_masked(struct cls_rule *, const struct in6_addr *,
- const struct in6_addr *);
+void cls_rule_init(struct cls_rule *, const struct match *,
+ unsigned int priority);
+void cls_rule_init_from_minimatch(struct cls_rule *, const struct minimatch *,
+ unsigned int priority);
+void cls_rule_clone(struct cls_rule *, const struct cls_rule *);
+void cls_rule_move(struct cls_rule *dst, struct cls_rule *src);
+void cls_rule_destroy(struct cls_rule *);
bool cls_rule_equal(const struct cls_rule *, const struct cls_rule *);
uint32_t cls_rule_hash(const struct cls_rule *, uint32_t basis);
void cls_rule_format(const struct cls_rule *, struct ds *);
-char *cls_rule_to_string(const struct cls_rule *);
-void cls_rule_print(const struct cls_rule *);
-void classifier_init(struct classifier *);
+bool cls_rule_is_catchall(const struct cls_rule *);
+
+bool cls_rule_is_loose_match(const struct cls_rule *rule,
+ const struct minimatch *criteria);
+
+void classifier_init(struct classifier *cls, const uint8_t *flow_segments);
void classifier_destroy(struct classifier *);
-bool classifier_is_empty(const struct classifier *);
-int classifier_count(const struct classifier *);
-void classifier_insert(struct classifier *, struct cls_rule *);
-struct cls_rule *classifier_replace(struct classifier *, struct cls_rule *);
-void classifier_remove(struct classifier *, struct cls_rule *);
-struct cls_rule *classifier_lookup(const struct classifier *,
- const struct flow *);
-bool classifier_rule_overlaps(const struct classifier *,
- const struct cls_rule *);
+void classifier_set_prefix_fields(struct classifier *cls,
+ const enum mf_field_id *trie_fields,
+ unsigned int n_trie_fields)
+ OVS_REQ_WRLOCK(cls->rwlock);
+
+bool classifier_is_empty(const struct classifier *cls)
+ OVS_REQ_RDLOCK(cls->rwlock);
+int classifier_count(const struct classifier *cls)
+ OVS_REQ_RDLOCK(cls->rwlock);
+void classifier_insert(struct classifier *cls, struct cls_rule *)
+ OVS_REQ_WRLOCK(cls->rwlock);
+struct cls_rule *classifier_replace(struct classifier *cls, struct cls_rule *)
+ OVS_REQ_WRLOCK(cls->rwlock);
+void classifier_remove(struct classifier *cls, struct cls_rule *)
+ OVS_REQ_WRLOCK(cls->rwlock);
+struct cls_rule *classifier_lookup(const struct classifier *cls,
+ const struct flow *,
+ struct flow_wildcards *)
+ OVS_REQ_RDLOCK(cls->rwlock);
+struct cls_rule *classifier_lookup_miniflow_first(const struct classifier *cls,
+ const struct miniflow *)
+ OVS_REQ_RDLOCK(cls->rwlock);
+bool classifier_rule_overlaps(const struct classifier *cls,
+ const struct cls_rule *)
+ OVS_REQ_RDLOCK(cls->rwlock);
typedef void cls_cb_func(struct cls_rule *, void *aux);
-struct cls_rule *classifier_find_rule_exactly(const struct classifier *,
- const struct cls_rule *);
+struct cls_rule *classifier_find_rule_exactly(const struct classifier *cls,
+ const struct cls_rule *)
+ OVS_REQ_RDLOCK(cls->rwlock);
+struct cls_rule *classifier_find_match_exactly(const struct classifier *cls,
+ const struct match *,
+ unsigned int priority)
+ OVS_REQ_RDLOCK(cls->rwlock);
\f
/* Iteration. */
struct cls_cursor {
- const struct classifier *cls;
- const struct cls_table *table;
+ const struct cls_classifier *cls;
+ const struct cls_subtable *subtable;
const struct cls_rule *target;
};
-void cls_cursor_init(struct cls_cursor *, const struct classifier *,
- const struct cls_rule *match);
-struct cls_rule *cls_cursor_first(struct cls_cursor *);
-struct cls_rule *cls_cursor_next(struct cls_cursor *, struct cls_rule *);
+void cls_cursor_init(struct cls_cursor *cursor, const struct classifier *cls,
+ const struct cls_rule *match) OVS_REQ_RDLOCK(cls->rwlock);
+struct cls_rule *cls_cursor_first(struct cls_cursor *cursor);
+struct cls_rule *cls_cursor_next(struct cls_cursor *, const struct cls_rule *);
#define CLS_CURSOR_FOR_EACH(RULE, MEMBER, CURSOR) \
for (ASSIGN_CONTAINER(RULE, cls_cursor_first(CURSOR), MEMBER); \
- &(RULE)->MEMBER != NULL; \
+ RULE != OBJECT_CONTAINING(NULL, RULE, MEMBER); \
ASSIGN_CONTAINER(RULE, cls_cursor_next(CURSOR, &(RULE)->MEMBER), \
MEMBER))
#define CLS_CURSOR_FOR_EACH_SAFE(RULE, NEXT, MEMBER, CURSOR) \
for (ASSIGN_CONTAINER(RULE, cls_cursor_first(CURSOR), MEMBER); \
- (&(RULE)->MEMBER != NULL \
+ (RULE != OBJECT_CONTAINING(NULL, RULE, MEMBER) \
? ASSIGN_CONTAINER(NEXT, cls_cursor_next(CURSOR, &(RULE)->MEMBER), \
- MEMBER) \
+ MEMBER), 1 \
: 0); \
(RULE) = (NEXT))
git://git.onelab.eu / sliver-openvswitch.git / blobdiff