ib_pathrec.c

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/*
 * Copyright (C) 2009 Michael Brown <mbrown@fensystems.co.uk>.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 *
 * You can also choose to distribute this program under the terms of
 * the Unmodified Binary Distribution Licence (as given in the file
 * COPYING.UBDL), provided that you have satisfied its requirements.
 */

FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );

#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <byteswap.h>
#include <errno.h>
#include <ipxe/infiniband.h>
#include <ipxe/ib_mi.h>
#include <ipxe/ib_pathrec.h>

/** @file
 *
 * Infiniband path lookups
 *
 */

/**
 * Handle path transaction completion
 *
 * @v ibdev             Infiniband device
 * @v mi                Management interface
 * @v madx              Management transaction
 * @v rc                Status code
 * @v mad               Received MAD (or NULL on error)
 * @v av                Source address vector (or NULL on error)
 */
static void ib_path_complete ( struct ib_device *ibdev,
                               struct ib_mad_interface *mi,
                               struct ib_mad_transaction *madx,
                               int rc, union ib_mad *mad,
                               struct ib_address_vector *av __unused ) {
        struct ib_path *path = ib_madx_get_ownerdata ( madx );
        union ib_gid *dgid = &path->av.gid;
        struct ib_path_record *pathrec = &mad->sa.sa_data.path_record;

        /* Report failures */
        if ( ( rc == 0 ) && ( mad->hdr.status != htons ( IB_MGMT_STATUS_OK ) ))
                rc = -ENETUNREACH;
        if ( rc != 0 ) {
                DBGC ( ibdev, "IBDEV %s path lookup for " IB_GID_FMT
                       " failed: %s\n",
                       ibdev->name, IB_GID_ARGS ( dgid ), strerror ( rc ) );
                goto out;
        }

        /* Extract values from MAD */
        path->av.lid = ntohs ( pathrec->dlid );
        path->av.sl = ( pathrec->reserved__sl & 0x0f );
        path->av.rate = ( pathrec->rate_selector__rate & 0x3f );
        DBGC ( ibdev, "IBDEV %s path to " IB_GID_FMT " lid %d sl %d rate "
               "%d\n", ibdev->name, IB_GID_ARGS ( dgid ), path->av.lid,
               path->av.sl, path->av.rate );

        /* Use only the LID if no GRH is needed for this path */
        if ( memcmp ( &path->av.gid.s.prefix, &ibdev->gid.s.prefix,
                      sizeof ( path->av.gid.s.prefix ) ) == 0 ) {
                path->av.gid_present = 0;
        }

 out:
        /* Destroy the completed transaction */
        ib_destroy_madx ( ibdev, mi, madx );
        path->madx = NULL;

        /* Hand off to upper completion handler */
        path->op->complete ( ibdev, path, rc, &path->av );
}

/** Path transaction completion operations */
static struct ib_mad_transaction_operations ib_path_op = {
        .complete = ib_path_complete,
};

/**
 * Create path
 *
 * @v ibdev             Infiniband device
 * @v av                Address vector to complete
 * @v op                Path operations
 * @ret path            Path
 */
struct ib_path *
ib_create_path ( struct ib_device *ibdev, struct ib_address_vector *av,
                 struct ib_path_operations *op ) {
        struct ib_path *path;
        union ib_mad mad;
        struct ib_mad_sa *sa = &mad.sa;

        /* Allocate and initialise structure */
        path = zalloc ( sizeof ( *path ) );
        if ( ! path )
                goto err_alloc_path;
        path->ibdev = ibdev;
        memcpy ( &path->av, av, sizeof ( path->av ) );
        path->op = op;

        /* Construct path request */
        memset ( sa, 0, sizeof ( *sa ) );
        sa->mad_hdr.mgmt_class = IB_MGMT_CLASS_SUBN_ADM;
        sa->mad_hdr.class_version = IB_SA_CLASS_VERSION;
        sa->mad_hdr.method = IB_MGMT_METHOD_GET;
        sa->mad_hdr.attr_id = htons ( IB_SA_ATTR_PATH_REC );
        sa->sa_hdr.comp_mask[1] =
                htonl ( IB_SA_PATH_REC_DGID | IB_SA_PATH_REC_SGID );
        memcpy ( &sa->sa_data.path_record.dgid, &path->av.gid,
                 sizeof ( sa->sa_data.path_record.dgid ) );
        memcpy ( &sa->sa_data.path_record.sgid, &ibdev->gid,
                 sizeof ( sa->sa_data.path_record.sgid ) );

        /* Create management transaction */
        path->madx = ib_create_madx ( ibdev, ibdev->gsi, &mad, NULL,
                                      &ib_path_op );
        if ( ! path->madx )
                goto err_create_madx;
        ib_madx_set_ownerdata ( path->madx, path );

        return path;

        ib_destroy_madx ( ibdev, ibdev->gsi, path->madx );
 err_create_madx:
        free ( path );
 err_alloc_path:
        return NULL;
}

/**
 * Destroy path
 *
 * @v ibdev             Infiniband device
 * @v path              Path
 */
void ib_destroy_path ( struct ib_device *ibdev, struct ib_path *path ) {

        if ( path->madx )
                ib_destroy_madx ( ibdev, ibdev->gsi, path->madx );
        free ( path );
}

/** Number of path cache entries
 *
 * Must be a power of two.
 */
#define IB_NUM_CACHED_PATHS 4

/** A cached path */
struct ib_cached_path {
        /** Path */
        struct ib_path *path;
};

/** Path cache */
static struct ib_cached_path ib_path_cache[IB_NUM_CACHED_PATHS];

/** Oldest path cache entry index */
static unsigned int ib_path_cache_idx;

/**
 * Find path cache entry
 *
 * @v ibdev             Infiniband device
 * @v dgid              Destination GID
 * @ret path            Path cache entry, or NULL
 */
static struct ib_cached_path *
ib_find_path_cache_entry ( struct ib_device *ibdev, union ib_gid *dgid ) {
        struct ib_cached_path *cached;
        unsigned int i;

        for ( i = 0 ; i < IB_NUM_CACHED_PATHS ; i++ ) {
                cached = &ib_path_cache[i];
                if ( ! cached->path )
                        continue;
                if ( cached->path->ibdev != ibdev )
                        continue;
                if ( memcmp ( &cached->path->av.gid, dgid,
                              sizeof ( cached->path->av.gid ) ) != 0 )
                        continue;
                return cached;
        }

        return NULL;
}

/**
 * Handle cached path transaction completion
 *
 * @v ibdev             Infiniband device
 * @v path              Path
 * @v rc                Status code
 * @v av                Address vector, or NULL on error
 */
static void ib_cached_path_complete ( struct ib_device *ibdev,
                                      struct ib_path *path, int rc,
                                      struct ib_address_vector *av __unused ) {
        struct ib_cached_path *cached = ib_path_get_ownerdata ( path );

        /* If the transaction failed, erase the cache entry */
        if ( rc != 0 ) {
                /* Destroy the old cache entry */
                ib_destroy_path ( ibdev, path );
                memset ( cached, 0, sizeof ( *cached ) );
                return;
        }

        /* Do not destroy the completed transaction; we still need to
         * refer to the resolved path.
         */
}

/** Cached path transaction completion operations */
static struct ib_path_operations ib_cached_path_op = {
        .complete = ib_cached_path_complete,
};

/**
 * Resolve path
 *
 * @v ibdev             Infiniband device
 * @v av                Address vector to complete
 * @ret rc              Return status code
 *
 * This provides a non-transactional way to resolve a path, via a
 * cache similar to ARP.
 */
int ib_resolve_path ( struct ib_device *ibdev, struct ib_address_vector *av ) {
        union ib_gid *gid = &av->gid;
        struct ib_cached_path *cached;
        unsigned int cache_idx;

        /* Look in cache for a matching entry */
        cached = ib_find_path_cache_entry ( ibdev, gid );
        if ( cached && cached->path->av.lid ) {
                /* Populated entry found */
                av->lid = cached->path->av.lid;
                av->rate = cached->path->av.rate;
                av->sl = cached->path->av.sl;
                av->gid_present = cached->path->av.gid_present;
                DBGC2 ( ibdev, "IBDEV %s cache hit for " IB_GID_FMT "\n",
                        ibdev->name, IB_GID_ARGS ( gid ) );
                return 0;
        }
        DBGC ( ibdev, "IBDEV %s cache miss for " IB_GID_FMT "%s\n", ibdev->name,
               IB_GID_ARGS ( gid ), ( cached ? " (in progress)" : "" ) );

        /* If lookup is already in progress, do nothing */
        if ( cached )
                return -ENOENT;

        /* Locate a new cache entry to use */
        cache_idx = ( (ib_path_cache_idx++) % IB_NUM_CACHED_PATHS );
        cached = &ib_path_cache[cache_idx];

        /* Destroy the old cache entry */
        if ( cached->path )
                ib_destroy_path ( ibdev, cached->path );
        memset ( cached, 0, sizeof ( *cached ) );

        /* Create new path */
        cached->path = ib_create_path ( ibdev, av, &ib_cached_path_op );
        if ( ! cached->path ) {
                DBGC ( ibdev, "IBDEV %s could not create path\n",
                       ibdev->name );
                return -ENOMEM;
        }
        ib_path_set_ownerdata ( cached->path, cached );

        /* Not found yet */
        return -ENOENT;
}