l2_output.c

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/*
 * l2_output.c : layer 2 output packet processing
 *
 * Copyright (c) 2013 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 <vlib/vlib.h>
#include <vnet/vnet.h>
#include <vnet/pg/pg.h>
#include <vnet/ethernet/ethernet.h>
#include <vlib/cli.h>

#include <vppinfra/error.h>
#include <vppinfra/hash.h>
#include <vnet/l2/feat_bitmap.h>
#include <vnet/l2/l2_output.h>


// Feature graph node names
static char * l2output_feat_names[] = {
#define _(sym,name) name,
  foreach_l2output_feat
#undef _
};

char **l2output_get_feat_names(void) {
  return l2output_feat_names;
}

l2output_main_t l2output_main;

typedef struct {
  /* per-pkt trace data */ 
  u8 src[6];
  u8 dst[6];
  u32 sw_if_index;
} l2output_trace_t;

/* packet trace format function */
static u8 * format_l2output_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 *);
  l2output_trace_t * t = va_arg (*args, l2output_trace_t *);
  
  s = format (s, "l2-output: sw_if_index %d dst %U src %U",
              t->sw_if_index,
              format_ethernet_address, t->dst,
              format_ethernet_address, t->src);
  return s;
}


#define foreach_l2output_error                          \
_(L2OUTPUT,     "L2 output packets")                    \
_(EFP_DROP,     "L2 EFP filter pre-rewrite drops")      \
_(VTR_DROP,     "L2 output tag rewrite drops")          \
_(SHG_DROP,     "L2 split horizon drops")               \
_(DROP,         "L2 output drops")

typedef enum {
#define _(sym,str) L2OUTPUT_ERROR_##sym,
  foreach_l2output_error
#undef _
  L2OUTPUT_N_ERROR,
} l2output_error_t;

static char * l2output_error_strings[] = {
#define _(sym,string) string,
  foreach_l2output_error
#undef _
};

typedef enum {
  L2OUTPUT_NEXT_DROP,
  L2OUTPUT_N_NEXT,
} l2output_next_t;

// Return 0 if split horizon check passes, otherwise return non-zero
// Packets should not be transmitted out an interface with the same
// split-horizon group as the input interface, except if the shg is 0
// in which case the check always passes.
static_always_inline u32
split_horizon_violation (u8 shg1, u8 shg2)
{
  if (PREDICT_TRUE (shg1 == 0)) {
    return 0;
  } else {
    return shg1 == shg2;
  }
}


static vlib_node_registration_t l2output_node;

static uword
l2output_node_fn (vlib_main_t * vm,
                  vlib_node_runtime_t * node,
                  vlib_frame_t * frame)
{
  u32 n_left_from, * from, * to_next;
  l2output_next_t next_index;
  l2output_main_t * msm = &l2output_main;
  vlib_node_t *n = vlib_get_node (vm, l2output_node.index);
  u32 node_counter_base_index = n->error_heap_index;
  vlib_error_main_t * em = &vm->error_main;
  u32 cached_sw_if_index;
  u32 cached_next_index;

  /* Invalidate cache */
  cached_sw_if_index = ~0;
  cached_next_index = ~0;       /* warning be gone */

  from = vlib_frame_vector_args (frame);
  n_left_from = frame->n_vectors; /* number of packets to process */
  next_index = node->cached_next_index;

  while (n_left_from > 0)
    {
      u32 n_left_to_next;

      /* get space to enqueue frame to graph node "next_index" */
      vlib_get_next_frame (vm, node, next_index,
                           to_next, n_left_to_next);

      while (n_left_from >= 6 && n_left_to_next >= 2)
        {
          u32 bi0, bi1;
          vlib_buffer_t * b0, * b1;
          u32 next0, next1;
          u32 sw_if_index0, sw_if_index1;
          ethernet_header_t * h0, * h1;
          l2_output_config_t * config0, * config1;
          u32 feature_bitmap0, feature_bitmap1;
          
          /* Prefetch next iteration. */
          {
            vlib_buffer_t * p2, * p3, * p4 , * p5;
            u32 sw_if_index2, sw_if_index3;
            
            p2 = vlib_get_buffer (vm, from[2]);
            p3 = vlib_get_buffer (vm, from[3]);
            p4 = vlib_get_buffer (vm, from[4]);
            p5 = vlib_get_buffer (vm, from[5]);
            
            // Prefetch the buffer header for the N+2 loop iteration
            vlib_prefetch_buffer_header (p4, LOAD);
            vlib_prefetch_buffer_header (p5, LOAD);
            // Note: no need to prefetch packet data. This node doesn't reference it.

            // Prefetch the input config for the N+1 loop iteration
            // This depends on the buffer header above
            sw_if_index2 = vnet_buffer(p2)->sw_if_index[VLIB_TX];
            sw_if_index3 = vnet_buffer(p3)->sw_if_index[VLIB_TX];
            CLIB_PREFETCH (&msm->configs[sw_if_index2], CLIB_CACHE_LINE_BYTES, LOAD);
            CLIB_PREFETCH (&msm->configs[sw_if_index3], CLIB_CACHE_LINE_BYTES, LOAD);
          }

          /* speculatively enqueue b0 and b1 to the current next frame */
          /* bi is "buffer index", b is pointer to the buffer */
          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);
 
          /* TX interface handles */
          sw_if_index0 = vnet_buffer(b0)->sw_if_index[VLIB_TX];
          sw_if_index1 = vnet_buffer(b1)->sw_if_index[VLIB_TX];

          if (PREDICT_FALSE((node->flags & VLIB_NODE_FLAG_TRACE)))
            {
              h0 = vlib_buffer_get_current (b0);
              h1 = vlib_buffer_get_current (b1);
              if (b0->flags & VLIB_BUFFER_IS_TRACED) 
                {
                    l2output_trace_t *t = 
                      vlib_add_trace (vm, node, b0, sizeof (*t));
                    t->sw_if_index = sw_if_index0;
                    clib_memcpy(t->src, h0->src_address, 6);
                    clib_memcpy(t->dst, h0->dst_address, 6);
                  }
                if (b1->flags & VLIB_BUFFER_IS_TRACED) 
                  {
                    l2output_trace_t *t = 
                      vlib_add_trace (vm, node, b1, sizeof (*t));
                    t->sw_if_index = sw_if_index1;
                    clib_memcpy(t->src, h1->src_address, 6);
                    clib_memcpy(t->dst, h1->dst_address, 6);
                  }
              }

            em->counters[node_counter_base_index + L2OUTPUT_ERROR_L2OUTPUT] += 2;

            // Get config for the output interface
            config0 = vec_elt_at_index(msm->configs, sw_if_index0);
            config1 = vec_elt_at_index(msm->configs, sw_if_index1);
          
            // Get features from the config
            // TODO: mask out any non-applicable features
            feature_bitmap0 = config0->feature_bitmap;
            feature_bitmap1 = config1->feature_bitmap;

            // Determine next node
            l2_output_dispatch (msm->vlib_main,
                                msm->vnet_main,
                                node,
                                l2output_node.index,
                                &cached_sw_if_index,
                                &cached_next_index,
                                &msm->next_nodes,
                                b0,
                                sw_if_index0,
                                feature_bitmap0,
                                &next0);

            l2_output_dispatch (msm->vlib_main,
                                msm->vnet_main,
                                node,
                                l2output_node.index,
                                &cached_sw_if_index,
                                &cached_next_index,
                                &msm->next_nodes,
                                b1,
                                sw_if_index1,
                                feature_bitmap1,
                                &next1);

            // Perform output vlan tag rewrite and the pre-vtr EFP filter check.
            // The EFP Filter only needs to be run if there is an output VTR
            // configured. The flag for the post-vtr EFP Filter node is used
            // to trigger the pre-vtr check as well.

            if (PREDICT_FALSE (config0->output_vtr.push_and_pop_bytes)) {
              // Perform pre-vtr EFP filter check if configured
              u32 failed1 = (feature_bitmap0 & L2OUTPUT_FEAT_EFP_FILTER) &&
                            (l2_efp_filter_process(b0, &(config0->input_vtr)));
              u32 failed2 = l2_vtr_process(b0, &(config0->output_vtr));

              if (PREDICT_FALSE (failed1 | failed2)) {
                next0 = L2OUTPUT_NEXT_DROP;
                if (failed2) {
                  b0->error = node->errors[L2OUTPUT_ERROR_VTR_DROP];
                }
                if (failed1) {
                  b0->error = node->errors[L2OUTPUT_ERROR_EFP_DROP];
                }
              }
            }

            if (PREDICT_FALSE (config1->output_vtr.push_and_pop_bytes)) {
              // Perform pre-vtr EFP filter check if configured
              u32 failed1 = (feature_bitmap1 & L2OUTPUT_FEAT_EFP_FILTER) &&
                            (l2_efp_filter_process(b1, &(config1->input_vtr)));
              u32 failed2 = l2_vtr_process(b1, &(config1->output_vtr));

              if (PREDICT_FALSE (failed1 | failed2)) {
                next1 = L2OUTPUT_NEXT_DROP;
                if (failed2) {
                  b1->error = node->errors[L2OUTPUT_ERROR_VTR_DROP];
                }
                if (failed1) {
                  b1->error = node->errors[L2OUTPUT_ERROR_EFP_DROP];
                }
              }
            }
 
            // Perform the split horizon check
            // The check can only fail for non-zero shg's
            if (PREDICT_FALSE (config0->shg + config1->shg)) {
              // one of the checks might fail, check both
              if (split_horizon_violation (config0->shg, vnet_buffer(b0)->l2.shg)) {
                next0 = L2OUTPUT_NEXT_DROP;
                b0->error = node->errors[L2OUTPUT_ERROR_SHG_DROP];
              }
              if (split_horizon_violation (config1->shg, vnet_buffer(b1)->l2.shg)) {
                next1 = L2OUTPUT_NEXT_DROP;
                b1->error = node->errors[L2OUTPUT_ERROR_SHG_DROP];
              }
            }

            /* verify speculative enqueues, maybe switch current next frame */
            /* if next0==next1==next_index then nothing special needs to be done */
            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;
          ethernet_header_t * h0;
          l2_output_config_t *config0;
          u32 feature_bitmap0;

          /* 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);

          sw_if_index0 = vnet_buffer(b0)->sw_if_index[VLIB_TX];
 
          if (PREDICT_FALSE((node->flags & VLIB_NODE_FLAG_TRACE) 
                            && (b0->flags & VLIB_BUFFER_IS_TRACED))) {
            l2output_trace_t *t = 
               vlib_add_trace (vm, node, b0, sizeof (*t));
            t->sw_if_index = sw_if_index0;
            h0 = vlib_buffer_get_current (b0);
            clib_memcpy(t->src, h0->src_address, 6);
            clib_memcpy(t->dst, h0->dst_address, 6);
            }

          em->counters[node_counter_base_index + L2OUTPUT_ERROR_L2OUTPUT] += 1;

          // Get config for the output interface
          config0 = vec_elt_at_index(msm->configs, sw_if_index0);
          
          // Get features from the config
          // TODO: mask out any non-applicable features
          feature_bitmap0 = config0->feature_bitmap;

          // Determine next node
          l2_output_dispatch (msm->vlib_main,
                              msm->vnet_main,
                              node,
                              l2output_node.index,
                              &cached_sw_if_index,
                              &cached_next_index,
                              &msm->next_nodes,
                              b0,
                              sw_if_index0,
                              feature_bitmap0,
                              &next0);

          // Perform output vlan tag rewrite and the pre-vtr EFP filter check.
          // The EFP Filter only needs to be run if there is an output VTR
          // configured. The flag for the post-vtr EFP Filter node is used
          // to trigger the pre-vtr check as well.

          if (config0->output_vtr.push_and_pop_bytes) {
            // Perform pre-vtr EFP filter check if configured
            u32 failed1 = (feature_bitmap0 & L2OUTPUT_FEAT_EFP_FILTER) &&
                          (l2_efp_filter_process(b0, &(config0->input_vtr)));
            u32 failed2 = l2_vtr_process(b0, &(config0->output_vtr));

            if (PREDICT_FALSE (failed1 | failed2)) {
              next0 = L2OUTPUT_NEXT_DROP;
              if (failed2) {
                 b0->error = node->errors[L2OUTPUT_ERROR_VTR_DROP];
              }
              if (failed1) {
                b0->error = node->errors[L2OUTPUT_ERROR_EFP_DROP];
              }
            }
          }

          // Perform the split horizon check
          if (PREDICT_FALSE (split_horizon_violation (config0->shg, vnet_buffer(b0)->l2.shg))) {
            next0 = L2OUTPUT_NEXT_DROP;
            b0->error = node->errors[L2OUTPUT_ERROR_SHG_DROP];
          }

          /* 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;
}


VLIB_REGISTER_NODE (l2output_node,static) = {
  .function = l2output_node_fn,
  .name = "l2-output",
  .vector_size = sizeof (u32),
  .format_trace = format_l2output_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,
  
  .n_errors = ARRAY_LEN(l2output_error_strings),
  .error_strings = l2output_error_strings,

  .n_next_nodes = L2OUTPUT_N_NEXT,

  /* edit / add dispositions here */
  .next_nodes = {
        [L2OUTPUT_NEXT_DROP] = "error-drop",
  },
};

clib_error_t *l2output_init (vlib_main_t *vm)
{
  l2output_main_t * mp = &l2output_main;
    
  mp->vlib_main = vm;
  mp->vnet_main = vnet_get_main();

  // Create the config vector
  vec_validate(mp->configs, 100);  
  // Until we hook up the CLI config, just create 100 sw interface entries  and zero them

  // Initialize the feature next-node indexes
  feat_bitmap_init_next_nodes(vm,
                              l2output_node.index,
                              L2OUTPUT_N_FEAT,
                              l2output_get_feat_names(),
                              mp->next_nodes.feat_next_node_index);

  // Initialize the output node mapping table
  l2output_init_output_node_vec(&mp->next_nodes.output_node_index_vec);

  return 0;
}

VLIB_INIT_FUNCTION (l2output_init);

typedef struct {
  u32 node_index;
  u32 sw_if_index;
} output_node_mapping_rpc_args_t;

#if DPDK > 0
static void output_node_rpc_callback 
( output_node_mapping_rpc_args_t * a);

static void output_node_mapping_send_rpc 
(u32  node_index,
 u32 sw_if_index)
{
  output_node_mapping_rpc_args_t args;
  void vl_api_rpc_call_main_thread (void *fp, u8 * data, u32 data_length);

  args.node_index = node_index;
  args.sw_if_index = sw_if_index;

  vl_api_rpc_call_main_thread (output_node_rpc_callback, 
                               (u8 *) &args, sizeof (args));
}
#endif


// Create a mapping in the next node mapping table for the given sw_if_index
u32 l2output_create_output_node_mapping (
            vlib_main_t * vlib_main,
            vnet_main_t * vnet_main,
            u32           node_index,  // index of current node
            u32         * output_node_index_vec, 
            u32           sw_if_index) {

  u32                  next;  // index of next graph node
  vnet_hw_interface_t *hw0;
  u32                 *node;

  hw0 = vnet_get_sup_hw_interface (vnet_main, sw_if_index);

#if DPDK > 0
  uword                cpu_number;

  cpu_number = os_get_cpu_number();

  if (cpu_number)
    {
      u32 oldflags;

      oldflags = __sync_fetch_and_or(&hw0->flags,
                                     VNET_HW_INTERFACE_FLAG_L2OUTPUT_MAPPED);

      if ((oldflags & VNET_HW_INTERFACE_FLAG_L2OUTPUT_MAPPED) )
        return L2OUTPUT_NEXT_DROP;

      output_node_mapping_send_rpc (node_index, sw_if_index);
        return L2OUTPUT_NEXT_DROP;
    }
#endif

  // dynamically create graph node arc 
  next = vlib_node_add_next (vlib_main,
                             node_index,
                             hw0->output_node_index);

  // Initialize vector with the mapping

  node = vec_elt_at_index(output_node_index_vec, sw_if_index);
  *node = next;
 
  return next;
}

#if DPDK > 0
void output_node_rpc_callback (output_node_mapping_rpc_args_t *a)
{
  vlib_main_t * vm = vlib_get_main();
  vnet_main_t * vnm = vnet_get_main();
  l2output_main_t * mp = &l2output_main;

  (void) l2output_create_output_node_mapping 
    (vm, vnm, a->node_index, mp->next_nodes.output_node_index_vec, 
     a->sw_if_index);
}
#endif

// Get a pointer to the config for the given interface
l2_output_config_t * l2output_intf_config (u32 sw_if_index)
{
  l2output_main_t * mp = &l2output_main;
 
  vec_validate(mp->configs, sw_if_index);  
  return vec_elt_at_index(mp->configs, sw_if_index);
}

// Enable (or disable) the feature in the bitmap for the given interface
void l2output_intf_bitmap_enable (u32 sw_if_index,
                                  u32 feature_bitmap,
                                  u32 enable)
{
  l2output_main_t * mp = &l2output_main;
  l2_output_config_t *config;
 
  vec_validate(mp->configs, sw_if_index);  
  config = vec_elt_at_index(mp->configs, sw_if_index);

  if (enable) {
    config->feature_bitmap |= feature_bitmap;
  } else {
    config->feature_bitmap &= ~feature_bitmap;
  }
}