handoff.c

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/*
 * Copyright (c) 2016 Cisco and/or its affiliates.
 * 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 <vnet/vnet.h>
#include <vppinfra/xxhash.h>
#include <vlib/threads.h>
#include <vnet/handoff.h>
#include <vnet/feature/feature.h>

typedef struct
{
  uword *workers_bitmap;
  u32 *workers;
} per_inteface_handoff_data_t;

typedef struct
{
  u32 cached_next_index;
  u32 num_workers;
  u32 first_worker_index;

  per_inteface_handoff_data_t *if_data;

  /* Worker handoff index */
  u32 frame_queue_index;

  /* convenience variables */
  vlib_main_t *vlib_main;
  vnet_main_t *vnet_main;

    u64 (*hash_fn) (ethernet_header_t *);
} handoff_main_t;

handoff_main_t handoff_main;
vlib_node_registration_t handoff_dispatch_node;

typedef struct
{
  u32 sw_if_index;
  u32 next_worker_index;
  u32 buffer_index;
} worker_handoff_trace_t;

/* packet trace format function */
static u8 *
format_worker_handoff_trace (u8 * s, va_list * args)
{
  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
  CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
  worker_handoff_trace_t *t = va_arg (*args, worker_handoff_trace_t *);

  s =
    format (s, "worker-handoff: sw_if_index %d, next_worker %d, buffer 0x%x",
            t->sw_if_index, t->next_worker_index, t->buffer_index);
  return s;
}

vlib_node_registration_t handoff_node;

static uword
worker_handoff_node_fn (vlib_main_t * vm,
                        vlib_node_runtime_t * node, vlib_frame_t * frame)
{
  handoff_main_t *hm = &handoff_main;
  vlib_thread_main_t *tm = vlib_get_thread_main ();
  u32 n_left_from, *from;
  static __thread vlib_frame_queue_elt_t **handoff_queue_elt_by_worker_index;
  static __thread vlib_frame_queue_t **congested_handoff_queue_by_worker_index
    = 0;
  vlib_frame_queue_elt_t *hf = 0;
  int i;
  u32 n_left_to_next_worker = 0, *to_next_worker = 0;
  u32 next_worker_index = 0;
  u32 current_worker_index = ~0;

  if (PREDICT_FALSE (handoff_queue_elt_by_worker_index == 0))
    {
      vec_validate (handoff_queue_elt_by_worker_index, tm->n_vlib_mains - 1);

      vec_validate_init_empty (congested_handoff_queue_by_worker_index,
                               hm->first_worker_index + hm->num_workers - 1,
                               (vlib_frame_queue_t *) (~0));
    }

  from = vlib_frame_vector_args (frame);
  n_left_from = frame->n_vectors;

  while (n_left_from > 0)
    {
      u32 bi0;
      vlib_buffer_t *b0;
      u32 sw_if_index0;
      u32 hash;
      u64 hash_key;
      per_inteface_handoff_data_t *ihd0;
      u32 index0;

      bi0 = from[0];
      from += 1;
      n_left_from -= 1;

      b0 = vlib_get_buffer (vm, bi0);
      sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
      ASSERT (hm->if_data);
      ihd0 = vec_elt_at_index (hm->if_data, sw_if_index0);

      next_worker_index = hm->first_worker_index;

      /*
       * Force unknown traffic onto worker 0,
       * and into ethernet-input. $$$$ add more hashes.
       */

      /* Compute ingress LB hash */
      hash_key = hm->hash_fn ((ethernet_header_t *) b0->data);
      hash = (u32) clib_xxhash (hash_key);

      /* if input node did not specify next index, then packet
         should go to eternet-input */
      if (PREDICT_FALSE ((b0->flags & VNET_BUFFER_F_HANDOFF_NEXT_VALID) == 0))
        vnet_buffer (b0)->handoff.next_index =
          HANDOFF_DISPATCH_NEXT_ETHERNET_INPUT;
      else if (vnet_buffer (b0)->handoff.next_index ==
               HANDOFF_DISPATCH_NEXT_IP4_INPUT
               || vnet_buffer (b0)->handoff.next_index ==
               HANDOFF_DISPATCH_NEXT_IP6_INPUT
               || vnet_buffer (b0)->handoff.next_index ==
               HANDOFF_DISPATCH_NEXT_MPLS_INPUT)
        vlib_buffer_advance (b0, (sizeof (ethernet_header_t)));

      if (PREDICT_TRUE (is_pow2 (vec_len (ihd0->workers))))
        index0 = hash & (vec_len (ihd0->workers) - 1);
      else
        index0 = hash % vec_len (ihd0->workers);

      next_worker_index += ihd0->workers[index0];

      if (next_worker_index != current_worker_index)
        {
          if (hf)
            hf->n_vectors = VLIB_FRAME_SIZE - n_left_to_next_worker;

          hf = vlib_get_worker_handoff_queue_elt (hm->frame_queue_index,
                                                  next_worker_index,
                                                  handoff_queue_elt_by_worker_index);

          n_left_to_next_worker = VLIB_FRAME_SIZE - hf->n_vectors;
          to_next_worker = &hf->buffer_index[hf->n_vectors];
          current_worker_index = next_worker_index;
        }

      /* enqueue to correct worker thread */
      to_next_worker[0] = bi0;
      to_next_worker++;
      n_left_to_next_worker--;

      if (n_left_to_next_worker == 0)
        {
          hf->n_vectors = VLIB_FRAME_SIZE;
          vlib_put_frame_queue_elt (hf);
          current_worker_index = ~0;
          handoff_queue_elt_by_worker_index[next_worker_index] = 0;
          hf = 0;
        }

      if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
                         && (b0->flags & VLIB_BUFFER_IS_TRACED)))
        {
          worker_handoff_trace_t *t =
            vlib_add_trace (vm, node, b0, sizeof (*t));
          t->sw_if_index = sw_if_index0;
          t->next_worker_index = next_worker_index - hm->first_worker_index;
          t->buffer_index = bi0;
        }

    }

  if (hf)
    hf->n_vectors = VLIB_FRAME_SIZE - n_left_to_next_worker;

  /* Ship frames to the worker nodes */
  for (i = 0; i < vec_len (handoff_queue_elt_by_worker_index); i++)
    {
      if (handoff_queue_elt_by_worker_index[i])
        {
          hf = handoff_queue_elt_by_worker_index[i];
          /*
           * It works better to let the handoff node
           * rate-adapt, always ship the handoff queue element.
           */
          if (1 || hf->n_vectors == hf->last_n_vectors)
            {
              vlib_put_frame_queue_elt (hf);
              handoff_queue_elt_by_worker_index[i] = 0;
            }
          else
            hf->last_n_vectors = hf->n_vectors;
        }
      congested_handoff_queue_by_worker_index[i] =
        (vlib_frame_queue_t *) (~0);
    }
  hf = 0;
  current_worker_index = ~0;
  return frame->n_vectors;
}

/* *INDENT-OFF* */
VLIB_REGISTER_NODE (worker_handoff_node) = {
  .function = worker_handoff_node_fn,
  .name = "worker-handoff",
  .vector_size = sizeof (u32),
  .format_trace = format_worker_handoff_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,

  .n_next_nodes = 1,
  .next_nodes = {
    [0] = "error-drop",
  },
};

VLIB_NODE_FUNCTION_MULTIARCH (worker_handoff_node, worker_handoff_node_fn)
/* *INDENT-ON* */

int
interface_handoff_enable_disable (vlib_main_t * vm, u32 sw_if_index,
                                  uword * bitmap, int enable_disable)
{
  handoff_main_t *hm = &handoff_main;
  vnet_sw_interface_t *sw;
  vnet_main_t *vnm = vnet_get_main ();
  per_inteface_handoff_data_t *d;
  int i, rv = 0;

  if (pool_is_free_index (vnm->interface_main.sw_interfaces, sw_if_index))
    return VNET_API_ERROR_INVALID_SW_IF_INDEX;

  sw = vnet_get_sw_interface (vnm, sw_if_index);
  if (sw->type != VNET_SW_INTERFACE_TYPE_HARDWARE)
    return VNET_API_ERROR_INVALID_SW_IF_INDEX;

  if (clib_bitmap_last_set (bitmap) >= hm->num_workers)
    return VNET_API_ERROR_INVALID_WORKER;

  if (hm->frame_queue_index == ~0)
    hm->frame_queue_index =
      vlib_frame_queue_main_init (handoff_dispatch_node.index, 0);

  vec_validate (hm->if_data, sw_if_index);
  d = vec_elt_at_index (hm->if_data, sw_if_index);

  vec_free (d->workers);
  vec_free (d->workers_bitmap);

  if (enable_disable)
    {
      d->workers_bitmap = bitmap;
      /* *INDENT-OFF* */
      clib_bitmap_foreach (i, bitmap,
        ({
          vec_add1(d->workers, i);
        }));
      /* *INDENT-ON* */
    }

  vnet_feature_enable_disable ("device-input", "worker-handoff",
                               sw_if_index, enable_disable, 0, 0);
  return rv;
}

static clib_error_t *
set_interface_handoff_command_fn (vlib_main_t * vm,
                                  unformat_input_t * input,
                                  vlib_cli_command_t * cmd)
{
  handoff_main_t *hm = &handoff_main;
  u32 sw_if_index = ~0;
  int enable_disable = 1;
  uword *bitmap = 0;
  u32 sym = ~0;

  int rv = 0;

  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
    {
      if (unformat (input, "disable"))
        enable_disable = 0;
      else if (unformat (input, "workers %U", unformat_bitmap_list, &bitmap))
        ;
      else if (unformat (input, "%U", unformat_vnet_sw_interface,
                         vnet_get_main (), &sw_if_index))
        ;
      else if (unformat (input, "symmetrical"))
        sym = 1;
      else if (unformat (input, "asymmetrical"))
        sym = 0;
      else
        break;
    }

  if (sw_if_index == ~0)
    return clib_error_return (0, "Please specify an interface...");

  if (bitmap == 0)
    return clib_error_return (0, "Please specify list of workers...");

  rv =
    interface_handoff_enable_disable (vm, sw_if_index, bitmap,
                                      enable_disable);

  switch (rv)
    {
    case 0:
      break;

    case VNET_API_ERROR_INVALID_SW_IF_INDEX:
      return clib_error_return (0, "Invalid interface");
      break;

    case VNET_API_ERROR_INVALID_WORKER:
      return clib_error_return (0, "Invalid worker(s)");
      break;

    case VNET_API_ERROR_UNIMPLEMENTED:
      return clib_error_return (0,
                                "Device driver doesn't support redirection");
      break;

    default:
      return clib_error_return (0, "unknown return value %d", rv);
    }

  if (sym == 1)
    hm->hash_fn = eth_get_sym_key;
  else if (sym == 0)
    hm->hash_fn = eth_get_key;

  return 0;
}

/* *INDENT-OFF* */
VLIB_CLI_COMMAND (set_interface_handoff_command, static) = {
  .path = "set interface handoff",
  .short_help =
  "set interface handoff <interface-name> workers <workers-list> [symmetrical|asymmetrical]",
  .function = set_interface_handoff_command_fn,
};
/* *INDENT-ON* */

typedef struct
{
  u32 buffer_index;
  u32 next_index;
  u32 sw_if_index;
} handoff_dispatch_trace_t;

/* packet trace format function */
static u8 *
format_handoff_dispatch_trace (u8 * s, va_list * args)
{
  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
  CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
  handoff_dispatch_trace_t *t = va_arg (*args, handoff_dispatch_trace_t *);

  s = format (s, "handoff-dispatch: sw_if_index %d next_index %d buffer 0x%x",
              t->sw_if_index, t->next_index, t->buffer_index);
  return s;
}

#define foreach_handoff_dispatch_error \
_(EXAMPLE, "example packets")

typedef enum
{
#define _(sym,str) HANDOFF_DISPATCH_ERROR_##sym,
  foreach_handoff_dispatch_error
#undef _
    HANDOFF_DISPATCH_N_ERROR,
} handoff_dispatch_error_t;

static char *handoff_dispatch_error_strings[] = {
#define _(sym,string) string,
  foreach_handoff_dispatch_error
#undef _
};

static uword
handoff_dispatch_node_fn (vlib_main_t * vm,
                          vlib_node_runtime_t * node, vlib_frame_t * frame)
{
  u32 n_left_from, *from, *to_next;
  handoff_dispatch_next_t next_index;

  from = vlib_frame_vector_args (frame);
  n_left_from = frame->n_vectors;
  next_index = node->cached_next_index;

  while (n_left_from > 0)
    {
      u32 n_left_to_next;

      vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);

      while (n_left_from >= 4 && n_left_to_next >= 2)
        {
          u32 bi0, bi1;
          vlib_buffer_t *b0, *b1;
          u32 next0, next1;
          u32 sw_if_index0, sw_if_index1;

          /* Prefetch next iteration. */
          {
            vlib_buffer_t *p2, *p3;

            p2 = vlib_get_buffer (vm, from[2]);
            p3 = vlib_get_buffer (vm, from[3]);

            vlib_prefetch_buffer_header (p2, LOAD);
            vlib_prefetch_buffer_header (p3, LOAD);
          }

          /* speculatively enqueue b0 and b1 to the current next frame */
          to_next[0] = bi0 = from[0];
          to_next[1] = bi1 = from[1];
          from += 2;
          to_next += 2;
          n_left_from -= 2;
          n_left_to_next -= 2;

          b0 = vlib_get_buffer (vm, bi0);
          b1 = vlib_get_buffer (vm, bi1);

          next0 = vnet_buffer (b0)->handoff.next_index;
          next1 = vnet_buffer (b1)->handoff.next_index;

          if (PREDICT_FALSE (vm->trace_main.trace_active_hint))
            {
              if (PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
                {
                  vlib_trace_buffer (vm, node, next0, b0,       /* follow_chain */
                                     0);
                  handoff_dispatch_trace_t *t =
                    vlib_add_trace (vm, node, b0, sizeof (*t));
                  sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
                  t->sw_if_index = sw_if_index0;
                  t->next_index = next0;
                  t->buffer_index = bi0;
                }
              if (PREDICT_FALSE (b1->flags & VLIB_BUFFER_IS_TRACED))
                {
                  vlib_trace_buffer (vm, node, next1, b1,       /* follow_chain */
                                     0);
                  handoff_dispatch_trace_t *t =
                    vlib_add_trace (vm, node, b1, sizeof (*t));
                  sw_if_index1 = vnet_buffer (b1)->sw_if_index[VLIB_RX];
                  t->sw_if_index = sw_if_index1;
                  t->next_index = next1;
                  t->buffer_index = bi1;
                }
            }

          /* verify speculative enqueues, maybe switch current next frame */
          vlib_validate_buffer_enqueue_x2 (vm, node, next_index,
                                           to_next, n_left_to_next,
                                           bi0, bi1, next0, next1);
        }

      while (n_left_from > 0 && n_left_to_next > 0)
        {
          u32 bi0;
          vlib_buffer_t *b0;
          u32 next0;
          u32 sw_if_index0;

          /* speculatively enqueue b0 to the current next frame */
          bi0 = from[0];
          to_next[0] = bi0;
          from += 1;
          to_next += 1;
          n_left_from -= 1;
          n_left_to_next -= 1;

          b0 = vlib_get_buffer (vm, bi0);

          next0 = vnet_buffer (b0)->handoff.next_index;

          if (PREDICT_FALSE (vm->trace_main.trace_active_hint))
            {
              if (PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
                {
                  vlib_trace_buffer (vm, node, next0, b0,       /* follow_chain */
                                     0);
                  handoff_dispatch_trace_t *t =
                    vlib_add_trace (vm, node, b0, sizeof (*t));
                  sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
                  t->sw_if_index = sw_if_index0;
                  t->next_index = next0;
                  t->buffer_index = bi0;
                }
            }

          /* verify speculative enqueue, maybe switch current next frame */
          vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
                                           to_next, n_left_to_next,
                                           bi0, next0);
        }

      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
    }

  return frame->n_vectors;
}

/* *INDENT-OFF* */
VLIB_REGISTER_NODE (handoff_dispatch_node) = {
  .function = handoff_dispatch_node_fn,
  .name = "handoff-dispatch",
  .vector_size = sizeof (u32),
  .format_trace = format_handoff_dispatch_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,
  .flags = VLIB_NODE_FLAG_IS_HANDOFF,

  .n_errors = ARRAY_LEN(handoff_dispatch_error_strings),
  .error_strings = handoff_dispatch_error_strings,

  .n_next_nodes = HANDOFF_DISPATCH_N_NEXT,

  .next_nodes = {
        [HANDOFF_DISPATCH_NEXT_DROP] = "error-drop",
        [HANDOFF_DISPATCH_NEXT_ETHERNET_INPUT] = "ethernet-input",
        [HANDOFF_DISPATCH_NEXT_IP4_INPUT] = "ip4-input-no-checksum",
        [HANDOFF_DISPATCH_NEXT_IP6_INPUT] = "ip6-input",
        [HANDOFF_DISPATCH_NEXT_MPLS_INPUT] = "mpls-input",
  },
};

VLIB_NODE_FUNCTION_MULTIARCH (handoff_dispatch_node, handoff_dispatch_node_fn)
/* *INDENT-ON* */

clib_error_t *
handoff_init (vlib_main_t * vm)
{
  handoff_main_t *hm = &handoff_main;
  vlib_thread_main_t *tm = vlib_get_thread_main ();
  clib_error_t *error;
  uword *p;

  if ((error = vlib_call_init_function (vm, threads_init)))
    return error;

  vlib_thread_registration_t *tr;
  /* Only the standard vnet worker threads are supported */
  p = hash_get_mem (tm->thread_registrations_by_name, "workers");
  if (p)
    {
      tr = (vlib_thread_registration_t *) p[0];
      if (tr)
        {
          hm->num_workers = tr->count;
          hm->first_worker_index = tr->first_index;
        }
    }

  hm->hash_fn = eth_get_key;

  hm->vlib_main = vm;
  hm->vnet_main = &vnet_main;

  hm->frame_queue_index = ~0;

  return 0;
}

VLIB_INIT_FUNCTION (handoff_init);

/*
 * fd.io coding-style-patch-verification: ON
 *
 * Local Variables:
 * eval: (c-set-style "gnu")
 * End:
 */