net/mlx5: control transmit doorbell register mapping

[dpdk.git] / drivers / net / mlx5 / mlx5.c

diff --git a/drivers/net/mlx5/mlx5.c b/drivers/net/mlx5/mlx5.c
index 9a2c711..276087d 100644 (file)
--- a/drivers/net/mlx5/mlx5.c
+++ b/drivers/net/mlx5/mlx5.c
@@ -95,6 +95,12 @@
 /* Device parameter to enable multi-packet send WQEs. */
 #define MLX5_TXQ_MPW_EN "txq_mpw_en"
 
+/*
+ * Device parameter to force doorbell register mapping
+ * to non-cahed region eliminating the extra write memory barrier.
+ */
+#define MLX5_TX_DB_NC "tx_db_nc"
+
 /*
  * Device parameter to include 2 dsegs in the title WQEBB.
  * Deprecated, ignored.
@@ -421,6 +427,37 @@ mlx5_get_pdn(struct ibv_pd *pd __rte_unused, uint32_t *pdn __rte_unused)
 }
 #endif /* HAVE_IBV_FLOW_DV_SUPPORT */
 
+static int
+mlx5_config_doorbell_mapping_env(const struct mlx5_dev_config *config)
+{
+       char *env;
+       int value;
+
+       assert(rte_eal_process_type() == RTE_PROC_PRIMARY);
+       /* Get environment variable to store. */
+       env = getenv(MLX5_SHUT_UP_BF);
+       value = env ? !!strcmp(env, "0") : MLX5_ARG_UNSET;
+       if (config->dbnc == MLX5_ARG_UNSET)
+               setenv(MLX5_SHUT_UP_BF, MLX5_SHUT_UP_BF_DEFAULT, 1);
+       else
+               setenv(MLX5_SHUT_UP_BF, config->dbnc ? "1" : "0", 1);
+       return value;
+}
+
+static void
+mlx5_restore_doorbell_mapping_env(const struct mlx5_dev_config *config,
+                                 int value)
+{
+       assert(rte_eal_process_type() == RTE_PROC_PRIMARY);
+       if (config->dbnc == MLX5_ARG_UNSET)
+               return;
+       /* Restore the original environment variable state. */
+       if (value == MLX5_ARG_UNSET)
+               unsetenv(MLX5_SHUT_UP_BF);
+       else
+               setenv(MLX5_SHUT_UP_BF, value ? "1" : "0", 1);
+}
+
 /**
  * Allocate shared IB device context. If there is multiport device the
  * master and representors will share this context, if there is single
@@ -434,22 +471,26 @@ mlx5_get_pdn(struct ibv_pd *pd __rte_unused, uint32_t *pdn __rte_unused)
  *
  * @param[in] spawn
  *   Pointer to the IB device attributes (name, port, etc).
+ * @param[in] config
+ *   Pointer to device configuration structure.
  *
  * @return
  *   Pointer to mlx5_ibv_shared object on success,
  *   otherwise NULL and rte_errno is set.
  */
 static struct mlx5_ibv_shared *
-mlx5_alloc_shared_ibctx(const struct mlx5_dev_spawn_data *spawn)
+mlx5_alloc_shared_ibctx(const struct mlx5_dev_spawn_data *spawn,
+                       const struct mlx5_dev_config *config)
 {
        struct mlx5_ibv_shared *sh;
+       int dbmap_env;
        int err = 0;
        uint32_t i;
 #ifdef HAVE_IBV_FLOW_DV_SUPPORT
        struct mlx5_devx_tis_attr tis_attr = { 0 };
 #endif
 
-assert(spawn);
+       assert(spawn);
        /* Secondary process should not create the shared context. */
        assert(rte_eal_process_type() == RTE_PROC_PRIMARY);
        pthread_mutex_lock(&mlx5_ibv_list_mutex);
@@ -472,16 +513,31 @@ assert(spawn);
                rte_errno  = ENOMEM;
                goto exit;
        }
+       /*
+        * Configure environment variable "MLX5_BF_SHUT_UP"
+        * before the device creation. The rdma_core library
+        * checks the variable at device creation and
+        * stores the result internally.
+        */
+       dbmap_env = mlx5_config_doorbell_mapping_env(config);
        /* Try to open IB device with DV first, then usual Verbs. */
        errno = 0;
        sh->ctx = mlx5_glue->dv_open_device(spawn->ibv_dev);
        if (sh->ctx) {
                sh->devx = 1;
                DRV_LOG(DEBUG, "DevX is supported");
+               /* The device is created, no need for environment. */
+               mlx5_restore_doorbell_mapping_env(config, dbmap_env);
        } else {
+               /* The environment variable is still configured. */
                sh->ctx = mlx5_glue->open_device(spawn->ibv_dev);
+               err = errno ? errno : ENODEV;
+               /*
+                * The environment variable is not needed anymore,
+                * all device creation attempts are completed.
+                */
+               mlx5_restore_doorbell_mapping_env(config, dbmap_env);
                if (!sh->ctx) {
-                       err = errno ? errno : ENODEV;
                        goto error;
                }
                DRV_LOG(DEBUG, "DevX is NOT supported");
@@ -1300,6 +1356,8 @@ mlx5_args_check(const char *key, const char *val, void *opaque)
                DRV_LOG(WARNING, "%s: deprecated parameter, ignored", key);
        } else if (strcmp(MLX5_TXQ_MPW_EN, key) == 0) {
                config->mps = !!tmp;
+       } else if (strcmp(MLX5_TX_DB_NC, key) == 0) {
+               config->dbnc = !!tmp;
        } else if (strcmp(MLX5_TXQ_MPW_HDR_DSEG_EN, key) == 0) {
                DRV_LOG(WARNING, "%s: deprecated parameter, ignored", key);
        } else if (strcmp(MLX5_TXQ_MAX_INLINE_LEN, key) == 0) {
@@ -1373,6 +1431,7 @@ mlx5_args(struct mlx5_dev_config *config, struct rte_devargs *devargs)
                MLX5_TXQ_MPW_EN,
                MLX5_TXQ_MPW_HDR_DSEG_EN,
                MLX5_TXQ_MAX_INLINE_LEN,
+               MLX5_TX_DB_NC,
                MLX5_TX_VEC_EN,
                MLX5_RX_VEC_EN,
                MLX5_L3_VXLAN_EN,
@@ -1938,7 +1997,20 @@ mlx5_dev_spawn(struct rte_device *dpdk_dev,
                eth_dev->tx_pkt_burst = mlx5_select_tx_function(eth_dev);
                return eth_dev;
        }
-       sh = mlx5_alloc_shared_ibctx(spawn);
+       /*
+        * Some parameters ("tx_db_nc" in particularly) are needed in
+        * advance to create dv/verbs device context. We proceed the
+        * devargs here to get ones, and later proceed devargs again
+        * to override some hardware settings.
+        */
+       err = mlx5_args(&config, dpdk_dev->devargs);
+       if (err) {
+               err = rte_errno;
+               DRV_LOG(ERR, "failed to process device arguments: %s",
+                       strerror(rte_errno));
+               goto error;
+       }
+       sh = mlx5_alloc_shared_ibctx(spawn, &config);
        if (!sh)
                return NULL;
        config.devx = sh->devx;
@@ -2180,13 +2252,8 @@ mlx5_dev_spawn(struct rte_device *dpdk_dev,
                }
                own_domain_id = 1;
        }
-       err = mlx5_args(&config, dpdk_dev->devargs);
-       if (err) {
-               err = rte_errno;
-               DRV_LOG(ERR, "failed to process device arguments: %s",
-                       strerror(rte_errno));
-               goto error;
-       }
+       /* Override some values set by hardware configuration. */
+       mlx5_args(&config, dpdk_dev->devargs);
        err = mlx5_dev_check_sibling_config(priv, &config);
        if (err)
                goto error;
@@ -3031,6 +3098,7 @@ mlx5_pci_probe(struct rte_pci_driver *pci_drv __rte_unused,
        dev_config = (struct mlx5_dev_config){
                .hw_padding = 0,
                .mps = MLX5_ARG_UNSET,
+               .dbnc = MLX5_ARG_UNSET,
                .rx_vec_en = 1,
                .txq_inline_max = MLX5_ARG_UNSET,
                .txq_inline_min = MLX5_ARG_UNSET,