The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/netinet/in_rss.c

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    1 /*-
    2  * Copyright (c) 2010-2011 Juniper Networks, Inc.
    3  * All rights reserved.
    4  *
    5  * This software was developed by Robert N. M. Watson under contract
    6  * to Juniper Networks, Inc.
    7  *
    8  * Redistribution and use in source and binary forms, with or without
    9  * modification, are permitted provided that the following conditions
   10  * are met:
   11  * 1. Redistributions of source code must retain the above copyright
   12  *    notice, this list of conditions and the following disclaimer.
   13  * 2. Redistributions in binary form must reproduce the above copyright
   14  *    notice, this list of conditions and the following disclaimer in the
   15  *    documentation and/or other materials provided with the distribution.
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   27  * SUCH DAMAGE.
   28  */
   29 
   30 #include <sys/cdefs.h>
   31 
   32 __FBSDID("$FreeBSD$");
   33 
   34 #include "opt_inet6.h"
   35 #include "opt_pcbgroup.h"
   36 
   37 #ifndef PCBGROUP
   38 #error "options RSS depends on options PCBGROUP"
   39 #endif
   40 
   41 #include <sys/param.h>
   42 #include <sys/mbuf.h>
   43 #include <sys/socket.h>
   44 #include <sys/priv.h>
   45 #include <sys/kernel.h>
   46 #include <sys/smp.h>
   47 #include <sys/sysctl.h>
   48 #include <sys/sbuf.h>
   49 
   50 #include <net/if.h>
   51 #include <net/if_var.h>
   52 #include <net/netisr.h>
   53 #include <net/rss_config.h>
   54 
   55 #include <netinet/in.h>
   56 #include <netinet/in_pcb.h>
   57 #include <netinet/in_rss.h>
   58 #include <netinet/in_var.h>
   59 
   60 /* for software rss hash support */
   61 #include <netinet/ip.h>
   62 #include <netinet/tcp.h>
   63 #include <netinet/udp.h>
   64 
   65 /*
   66  * Hash an IPv4 2-tuple.
   67  */
   68 uint32_t
   69 rss_hash_ip4_2tuple(struct in_addr src, struct in_addr dst)
   70 {
   71         uint8_t data[sizeof(src) + sizeof(dst)];
   72         u_int datalen;
   73 
   74         datalen = 0;
   75         bcopy(&src, &data[datalen], sizeof(src));
   76         datalen += sizeof(src);
   77         bcopy(&dst, &data[datalen], sizeof(dst));
   78         datalen += sizeof(dst);
   79         return (rss_hash(datalen, data));
   80 }
   81 
   82 /*
   83  * Hash an IPv4 4-tuple.
   84  */
   85 uint32_t
   86 rss_hash_ip4_4tuple(struct in_addr src, u_short srcport, struct in_addr dst,
   87     u_short dstport)
   88 {
   89         uint8_t data[sizeof(src) + sizeof(dst) + sizeof(srcport) +
   90             sizeof(dstport)];
   91         u_int datalen;
   92 
   93         datalen = 0;
   94         bcopy(&src, &data[datalen], sizeof(src));
   95         datalen += sizeof(src);
   96         bcopy(&dst, &data[datalen], sizeof(dst));
   97         datalen += sizeof(dst);
   98         bcopy(&srcport, &data[datalen], sizeof(srcport));
   99         datalen += sizeof(srcport);
  100         bcopy(&dstport, &data[datalen], sizeof(dstport));
  101         datalen += sizeof(dstport);
  102         return (rss_hash(datalen, data));
  103 }
  104 
  105 /*
  106  * Calculate an appropriate ipv4 2-tuple or 4-tuple given the given
  107  * IPv4 source/destination address, UDP or TCP source/destination ports
  108  * and the protocol type.
  109  *
  110  * The protocol code may wish to do a software hash of the given
  111  * tuple.  This depends upon the currently configured RSS hash types.
  112  *
  113  * This assumes that the packet in question isn't a fragment.
  114  *
  115  * It also assumes the packet source/destination address
  116  * are in "incoming" packet order (ie, source is "far" address.)
  117  */
  118 int
  119 rss_proto_software_hash_v4(struct in_addr s, struct in_addr d,
  120     u_short sp, u_short dp, int proto,
  121     uint32_t *hashval, uint32_t *hashtype)
  122 {
  123         uint32_t hash;
  124 
  125         /*
  126          * Next, choose the hash type depending upon the protocol
  127          * identifier.
  128          */
  129         if ((proto == IPPROTO_TCP) &&
  130             (rss_gethashconfig() & RSS_HASHTYPE_RSS_TCP_IPV4)) {
  131                 hash = rss_hash_ip4_4tuple(s, sp, d, dp);
  132                 *hashval = hash;
  133                 *hashtype = M_HASHTYPE_RSS_TCP_IPV4;
  134                 return (0);
  135         } else if ((proto == IPPROTO_UDP) &&
  136             (rss_gethashconfig() & RSS_HASHTYPE_RSS_UDP_IPV4)) {
  137                 hash = rss_hash_ip4_4tuple(s, sp, d, dp);
  138                 *hashval = hash;
  139                 *hashtype = M_HASHTYPE_RSS_UDP_IPV4;
  140                 return (0);
  141         } else if (rss_gethashconfig() & RSS_HASHTYPE_RSS_IPV4) {
  142                 /* RSS doesn't hash on other protocols like SCTP; so 2-tuple */
  143                 hash = rss_hash_ip4_2tuple(s, d);
  144                 *hashval = hash;
  145                 *hashtype = M_HASHTYPE_RSS_IPV4;
  146                 return (0);
  147         }
  148 
  149         /* No configured available hashtypes! */
  150         RSS_DEBUG("no available hashtypes!\n");
  151         return (-1);
  152 }
  153 
  154 /*
  155  * Do a software calculation of the RSS for the given mbuf.
  156  *
  157  * This is typically used by the input path to recalculate the RSS after
  158  * some form of packet processing (eg de-capsulation, IP fragment reassembly.)
  159  *
  160  * dir is the packet direction - RSS_HASH_PKT_INGRESS for incoming and
  161  * RSS_HASH_PKT_EGRESS for outgoing.
  162  *
  163  * Returns 0 if a hash was done, -1 if no hash was done, +1 if
  164  * the mbuf already had a valid RSS flowid.
  165  *
  166  * This function doesn't modify the mbuf.  It's up to the caller to
  167  * assign flowid/flowtype as appropriate.
  168  */
  169 int
  170 rss_mbuf_software_hash_v4(const struct mbuf *m, int dir, uint32_t *hashval,
  171     uint32_t *hashtype)
  172 {
  173         const struct ip *ip;
  174         const struct tcphdr *th;
  175         const struct udphdr *uh;
  176         uint32_t flowtype;
  177         uint8_t proto;
  178         int iphlen;
  179         int is_frag = 0;
  180 
  181         /*
  182          * XXX For now this only handles hashing on incoming mbufs.
  183          */
  184         if (dir != RSS_HASH_PKT_INGRESS) {
  185                 RSS_DEBUG("called on EGRESS packet!\n");
  186                 return (-1);
  187         }
  188 
  189         /*
  190          * First, validate that the mbuf we have is long enough
  191          * to have an IPv4 header in it.
  192          */
  193         if (m->m_pkthdr.len < (sizeof(struct ip))) {
  194                 RSS_DEBUG("short mbuf pkthdr\n");
  195                 return (-1);
  196         }
  197         if (m->m_len < (sizeof(struct ip))) {
  198                 RSS_DEBUG("short mbuf len\n");
  199                 return (-1);
  200         }
  201 
  202         /* Ok, let's dereference that */
  203         ip = mtod(m, struct ip *);
  204         proto = ip->ip_p;
  205         iphlen = ip->ip_hl << 2;
  206 
  207         /*
  208          * If this is a fragment then it shouldn't be four-tuple
  209          * hashed just yet.  Once it's reassembled into a full
  210          * frame it should be re-hashed.
  211          */
  212         if (ip->ip_off & htons(IP_MF | IP_OFFMASK))
  213                 is_frag = 1;
  214 
  215         /*
  216          * If the mbuf flowid/flowtype matches the packet type,
  217          * and we don't support the 4-tuple version of the given protocol,
  218          * then signal to the owner that it can trust the flowid/flowtype
  219          * details.
  220          *
  221          * This is a little picky - eg, if TCPv4 / UDPv4 hashing
  222          * is supported but we got a TCP/UDP frame only 2-tuple hashed,
  223          * then we shouldn't just "trust" the 2-tuple hash.  We need
  224          * a 4-tuple hash.
  225          */
  226         flowtype = M_HASHTYPE_GET(m);
  227 
  228         if (flowtype != M_HASHTYPE_NONE) {
  229                 switch (proto) {
  230                 case IPPROTO_UDP:
  231                         if ((rss_gethashconfig() & RSS_HASHTYPE_RSS_UDP_IPV4) &&
  232                             (flowtype == M_HASHTYPE_RSS_UDP_IPV4) &&
  233                             (is_frag == 0)) {
  234                                 return (1);
  235                         }
  236                         /*
  237                          * Only allow 2-tuple for UDP frames if we don't also
  238                          * support 4-tuple for UDP.
  239                          */
  240                         if ((rss_gethashconfig() & RSS_HASHTYPE_RSS_IPV4) &&
  241                             ((rss_gethashconfig() & RSS_HASHTYPE_RSS_UDP_IPV4) == 0) &&
  242                             flowtype == M_HASHTYPE_RSS_IPV4) {
  243                                 return (1);
  244                         }
  245                         break;
  246                 case IPPROTO_TCP:
  247                         if ((rss_gethashconfig() & RSS_HASHTYPE_RSS_TCP_IPV4) &&
  248                             (flowtype == M_HASHTYPE_RSS_TCP_IPV4) &&
  249                             (is_frag == 0)) {
  250                                 return (1);
  251                         }
  252                         /*
  253                          * Only allow 2-tuple for TCP frames if we don't also
  254                          * support 2-tuple for TCP.
  255                          */
  256                         if ((rss_gethashconfig() & RSS_HASHTYPE_RSS_IPV4) &&
  257                             ((rss_gethashconfig() & RSS_HASHTYPE_RSS_TCP_IPV4) == 0) &&
  258                             flowtype == M_HASHTYPE_RSS_IPV4) {
  259                                 return (1);
  260                         }
  261                         break;
  262                 default:
  263                         if ((rss_gethashconfig() & RSS_HASHTYPE_RSS_IPV4) &&
  264                             flowtype == M_HASHTYPE_RSS_IPV4) {
  265                                 return (1);
  266                         }
  267                         break;
  268                 }
  269         }
  270 
  271         /*
  272          * Decode enough information to make a hash decision.
  273          *
  274          * XXX TODO: does the hardware hash on 4-tuple if IP
  275          *    options are present?
  276          */
  277         if ((rss_gethashconfig() & RSS_HASHTYPE_RSS_TCP_IPV4) &&
  278             (proto == IPPROTO_TCP) &&
  279             (is_frag == 0)) {
  280                 if (m->m_len < iphlen + sizeof(struct tcphdr)) {
  281                         RSS_DEBUG("short TCP frame?\n");
  282                         return (-1);
  283                 }
  284                 th = (const struct tcphdr *)((c_caddr_t)ip + iphlen);
  285                 return rss_proto_software_hash_v4(ip->ip_src, ip->ip_dst,
  286                     th->th_sport,
  287                     th->th_dport,
  288                     proto,
  289                     hashval,
  290                     hashtype);
  291         } else if ((rss_gethashconfig() & RSS_HASHTYPE_RSS_UDP_IPV4) &&
  292             (proto == IPPROTO_UDP) &&
  293             (is_frag == 0)) {
  294                 uh = (const struct udphdr *)((c_caddr_t)ip + iphlen);
  295                 if (m->m_len < iphlen + sizeof(struct udphdr)) {
  296                         RSS_DEBUG("short UDP frame?\n");
  297                         return (-1);
  298                 }
  299                 return rss_proto_software_hash_v4(ip->ip_src, ip->ip_dst,
  300                     uh->uh_sport,
  301                     uh->uh_dport,
  302                     proto,
  303                     hashval,
  304                     hashtype);
  305         } else if (rss_gethashconfig() & RSS_HASHTYPE_RSS_IPV4) {
  306                 /* Default to 2-tuple hash */
  307                 return rss_proto_software_hash_v4(ip->ip_src, ip->ip_dst,
  308                     0,  /* source port */
  309                     0,  /* destination port */
  310                     0,  /* IPPROTO_IP */
  311                     hashval,
  312                     hashtype);
  313         } else {
  314                 RSS_DEBUG("no available hashtypes!\n");
  315                 return (-1);
  316         }
  317 }
  318 
  319 /*
  320  * Similar to rss_m2cpuid, but designed to be used by the IP NETISR
  321  * on incoming frames.
  322  *
  323  * If an existing RSS hash exists and it matches what the configured
  324  * hashing is, then use it.
  325  *
  326  * If there's an existing RSS hash but the desired hash is different,
  327  * or if there's no useful RSS hash, then calculate it via
  328  * the software path.
  329  *
  330  * XXX TODO: definitely want statistics here!
  331  */
  332 struct mbuf *
  333 rss_soft_m2cpuid_v4(struct mbuf *m, uintptr_t source, u_int *cpuid)
  334 {
  335         uint32_t hash_val, hash_type;
  336         int ret;
  337 
  338         M_ASSERTPKTHDR(m);
  339 
  340         ret = rss_mbuf_software_hash_v4(m, RSS_HASH_PKT_INGRESS,
  341             &hash_val, &hash_type);
  342         if (ret > 0) {
  343                 /* mbuf has a valid hash already; don't need to modify it */
  344                 *cpuid = rss_hash2cpuid(m->m_pkthdr.flowid, M_HASHTYPE_GET(m));
  345         } else if (ret == 0) {
  346                 /* hash was done; update */
  347                 m->m_pkthdr.flowid = hash_val;
  348                 M_HASHTYPE_SET(m, hash_type);
  349                 *cpuid = rss_hash2cpuid(m->m_pkthdr.flowid, M_HASHTYPE_GET(m));
  350         } else { /* ret < 0 */
  351                 /* no hash was done */
  352                 *cpuid = NETISR_CPUID_NONE;
  353         }
  354         return (m);
  355 }

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