/*

 * Copyright (c) 2020 Intel Corporation.

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at:

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

#include <config.h>

#include <errno.h>

#include "dpif-netdev-lookup.h"

#include "cpu.h"

#include "openvswitch/vlog.h"

VLOG_DEFINE_THIS_MODULE(dpif_netdev_lookup);

#define DPCLS_IMPL_AVX512_CHECK (__x86_64__ && HAVE_AVX512F \

    && HAVE_LD_AVX512_GOOD && HAVE_AVX512BW && __SSE4_2__)

#if DPCLS_IMPL_AVX512_CHECK

static dpcls_subtable_lookup_func

dpcls_subtable_avx512_gather_probe(uint32_t u0_bits, uint32_t u1_bits)

{

    if (!cpu_has_isa(OVS_CPU_ISA_X86_AVX512F)

        || !cpu_has_isa(OVS_CPU_ISA_X86_BMI2)) {

        return NULL;

    }

    return dpcls_subtable_avx512_gather_probe__(u0_bits, u1_bits,

        cpu_has_isa(OVS_CPU_ISA_X86_VPOPCNTDQ));

}

#endif

/* Actual list of implementations goes here */

static struct dpcls_subtable_lookup_info_t subtable_lookups[] = {

    /* The autovalidator implementation will not be used by default, it must

     * be enabled at compile time to be the default lookup implementation. The

     * user may enable it at runtime using the normal "prio-set" command if

     * desired. The compile time default switch is here to enable all unit

     * tests to transparently run with the autovalidator.

     */

#ifdef DPCLS_AUTOVALIDATOR_DEFAULT

    { .prio = 255,

#else

    { .prio = 0,

#endif

      .probe = dpcls_subtable_autovalidator_probe,

      .name = "autovalidator",

      .usage_cnt = ATOMIC_COUNT_INIT(0), },

    /* The default scalar C code implementation. */

    { .prio = 1,

      .probe = dpcls_subtable_generic_probe,

      .name = "generic",

      .usage_cnt = ATOMIC_COUNT_INIT(0), },

#if DPCLS_IMPL_AVX512_CHECK

    /* Only available on x86_64 bit builds with SSE 4.2 used for OVS core. */

    { .prio = 0,

      .probe = dpcls_subtable_avx512_gather_probe,

      .name = "avx512_gather",

      .usage_cnt = ATOMIC_COUNT_INIT(0), },

#else

    /* Disabling AVX512 at compile time, as compile time requirements not met.

     * This could be due to a number of reasons:

     *  1) core OVS is not compiled with SSE4.2 instruction set.

     *     The SSE42 instructions are required to use CRC32 ISA for high-

     *     performance hashing. Consider ./configure of OVS with -msse42 (or

     *     newer) to enable CRC32 hashing and higher performance.

     *  2) The assembler in binutils versions 2.30 and 2.31 has bugs in AVX512

     *     assembly. Compile time probes check for this assembler issue, and

     *     disable the HAVE_LD_AVX512_GOOD check if an issue is detected.

     *     Please upgrade binutils, or backport this binutils fix commit:

     *     2069ccaf8dc28ea699bd901fdd35d90613e4402a

     */

#endif

};

int

dpcls_subtable_lookup_info_get(struct dpcls_subtable_lookup_info_t **out_ptr)

{

    if (out_ptr == NULL) {

        return -1;

    }

    *out_ptr = subtable_lookups;

    return ARRAY_SIZE(subtable_lookups);

}

/* sets the priority of the lookup function with "name". */

int

dpcls_subtable_set_prio(const char *name, uint8_t priority)

{

    for (int i = 0; i < ARRAY_SIZE(subtable_lookups); i++) {

        if (strcmp(name, subtable_lookups[i].name) == 0) {

                subtable_lookups[i].prio = priority;

                VLOG_INFO("Subtable function '%s' set priority to %d\n",

                         name, priority);

                return 0;

        }

    }

    VLOG_WARN("Subtable function '%s' not found, failed to set priority\n",

              name);

    return -EINVAL;

}

dpcls_subtable_lookup_func

dpcls_subtable_get_best_impl(uint32_t u0_bit_count, uint32_t u1_bit_count,

                             struct dpcls_subtable_lookup_info_t **info)

{

    struct dpcls_subtable_lookup_info_t *best_info = NULL;

    dpcls_subtable_lookup_func best_func = NULL;

    int prio = -1;

    /* Iter over each subtable impl, and get highest priority one. */

    for (int i = 0; i < ARRAY_SIZE(subtable_lookups); i++) {

        struct dpcls_subtable_lookup_info_t *impl_info = &subtable_lookups[i];

        dpcls_subtable_lookup_func probed_func;

        if (impl_info->prio <= prio) {

            continue;

        }

        probed_func = subtable_lookups[i].probe(u0_bit_count,

                                                u1_bit_count);

        if (!probed_func) {

            continue;

        }

        best_func = probed_func;

        best_info = impl_info;

        prio = impl_info->prio;

    }

    /* Programming error - we must always return a valid func ptr. */

    ovs_assert(best_func != NULL && best_info != NULL);

    VLOG_DBG("Subtable lookup function '%s' with units (%d,%d), priority %d\n",

             best_info->name, u0_bit_count, u1_bit_count, prio);

    if (info) {

        *info = best_info;

    }

    return best_func;

}

void

dpcls_info_inc_usage(struct dpcls_subtable_lookup_info_t *info)

{

    if (info) {

        atomic_count_inc(&info->usage_cnt);

    }

}

void

dpcls_info_dec_usage(struct dpcls_subtable_lookup_info_t *info)

{

    if (info) {

        atomic_count_dec(&info->usage_cnt);

    }

}

void

dpcls_impl_print_stats(struct ds *reply)

{

    struct dpcls_subtable_lookup_info_t *lookup_funcs = NULL;

    int count = dpcls_subtable_lookup_info_get(&lookup_funcs);

    /* Add all DPCLS functions to reply string. */

    ds_put_cstr(reply, "Available dpcls implementations:\n");

    for (int i = 0; i < count; i++) {

        ds_put_format(reply, "  %s (Use count: %d, Priority: %d",

                      lookup_funcs[i].name,

                      atomic_count_get(&lookup_funcs[i].usage_cnt),

                      lookup_funcs[i].prio);

        if (ds_last(reply) == ' ') {

            ds_put_cstr(reply, "none");

        }

        ds_put_cstr(reply, ")\n");

    }

}