net/mlx4: enable secondary process to register DMA memory

The Memory Region (MR) for DMA memory can't be created from secondary
process due to lib/driver limitation. Whenever it is needed, secondary
process can make a request to primary process through the EAL IPC
channel (rte_mp_msg) which is established on initialization. Once a MR
is created by primary process, it is immediately visible to secondary
process because the MR list is global per a device. Thus, secondary
process can look up the list after the request is successfully returned.

Signed-off-by: Yongseok Koh <yskoh@mellanox.com>
Acked-by: Shahaf Shuler <shahafs@mellanox.com>

doc/guides/nics/mlx4.rst

@@ -159,7 +159,6 @@ Limitations
 - For secondary process:
 
   - Forked secondary process not supported.
-  - All mempools must be initialized before rte_eth_dev_start().
   - External memory unregistered in EAL memseg list cannot be used for DMA
     unless such memory has been registered by ``mlx4_mr_update_ext_mp()`` in
     primary process and remapped to the same virtual address in secondary

drivers/net/mlx4/mlx4.h

@@ -79,6 +79,7 @@ enum {
 /* Request types for IPC. */
 enum mlx4_mp_req_type {
 	MLX4_MP_REQ_VERBS_CMD_FD = 1,
+	MLX4_MP_REQ_CREATE_MR,
 	MLX4_MP_REQ_START_RXTX,
 	MLX4_MP_REQ_STOP_RXTX,
 };
@@ -88,6 +89,10 @@ struct mlx4_mp_param {
 	enum mlx4_mp_req_type type;
 	int port_id;
 	int result;
+	RTE_STD_C11
+	union {
+		uintptr_t addr; /* MLX4_MP_REQ_CREATE_MR */
+	} args;
 };
 
 /** Request timeout for IPC. */
@@ -235,6 +240,7 @@ int mlx4_rx_intr_enable(struct rte_eth_dev *dev, uint16_t idx);
 /* mlx4_mp.c */
 void mlx4_mp_req_start_rxtx(struct rte_eth_dev *dev);
 void mlx4_mp_req_stop_rxtx(struct rte_eth_dev *dev);
+int mlx4_mp_req_mr_create(struct rte_eth_dev *dev, uintptr_t addr);
 int mlx4_mp_req_verbs_cmd_fd(struct rte_eth_dev *dev);
 void mlx4_mp_init_primary(void);
 void mlx4_mp_uninit_primary(void);

drivers/net/mlx4/mlx4_mp.c

@@ -58,6 +58,8 @@ mp_primary_handle(const struct rte_mp_msg *mp_msg, const void *peer)
 		(const struct mlx4_mp_param *)mp_msg->param;
 	struct rte_eth_dev *dev;
 	struct mlx4_priv *priv;
+	struct mlx4_mr_cache entry;
+	uint32_t lkey;
 	int ret;
 
 	assert(rte_eal_process_type() == RTE_PROC_PRIMARY);
@@ -69,6 +71,13 @@ mp_primary_handle(const struct rte_mp_msg *mp_msg, const void *peer)
 	dev = &rte_eth_devices[param->port_id];
 	priv = dev->data->dev_private;
 	switch (param->type) {
+	case MLX4_MP_REQ_CREATE_MR:
+		mp_init_msg(dev, &mp_res, param->type);
+		lkey = mlx4_mr_create_primary(dev, &entry, param->args.addr);
+		if (lkey == UINT32_MAX)
+			res->result = -rte_errno;
+		ret = rte_mp_reply(&mp_res, peer);
+		break;
 	case MLX4_MP_REQ_VERBS_CMD_FD:
 		mp_init_msg(dev, &mp_res, param->type);
 		mp_res.num_fds = 1;
@@ -217,6 +226,47 @@ mlx4_mp_req_stop_rxtx(struct rte_eth_dev *dev)
 	mp_req_on_rxtx(dev, MLX4_MP_REQ_STOP_RXTX);
 }
 
+/**
+ * Request Memory Region creation to the primary process.
+ *
+ * @param[in] dev
+ *   Pointer to Ethernet structure.
+ * @param addr
+ *   Target virtual address to register.
+ *
+ * @return
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
+ */
+int
+mlx4_mp_req_mr_create(struct rte_eth_dev *dev, uintptr_t addr)
+{
+	struct rte_mp_msg mp_req;
+	struct rte_mp_msg *mp_res;
+	struct rte_mp_reply mp_rep;
+	struct mlx4_mp_param *req = (struct mlx4_mp_param *)mp_req.param;
+	struct mlx4_mp_param *res;
+	struct timespec ts = {.tv_sec = MLX4_MP_REQ_TIMEOUT_SEC, .tv_nsec = 0};
+	int ret;
+
+	assert(rte_eal_process_type() == RTE_PROC_SECONDARY);
+	mp_init_msg(dev, &mp_req, MLX4_MP_REQ_CREATE_MR);
+	req->args.addr = addr;
+	ret = rte_mp_request_sync(&mp_req, &mp_rep, &ts);
+	if (ret) {
+		ERROR("port %u request to primary process failed",
+		      dev->data->port_id);
+		return -rte_errno;
+	}
+	assert(mp_rep.nb_received == 1);
+	mp_res = &mp_rep.msgs[0];
+	res = (struct mlx4_mp_param *)mp_res->param;
+	ret = res->result;
+	if (ret)
+		rte_errno = -ret;
+	free(mp_rep.msgs);
+	return ret;
+}
+
 /**
  * IPC message handler of primary process.
  *

drivers/net/mlx4/mlx4_mr.c

@@ -528,7 +528,10 @@ mr_find_contig_memsegs_cb(const struct rte_memseg_list *msl,
 
 /**
  * Create a new global Memroy Region (MR) for a missing virtual address.
- * Register entire virtually contiguous memory chunk around the address.
+ * This API should be called on a secondary process, then a request is sent to
+ * the primary process in order to create a MR for the address. As the global MR
+ * list is on the shared memory, following LKey lookup should succeed unless the
+ * request fails.
  *
  * @param dev
  *   Pointer to Ethernet device.
@@ -542,8 +545,52 @@ mr_find_contig_memsegs_cb(const struct rte_memseg_list *msl,
  *   Searched LKey on success, UINT32_MAX on failure and rte_errno is set.
  */
 static uint32_t
-mlx4_mr_create(struct rte_eth_dev *dev, struct mlx4_mr_cache *entry,
-	       uintptr_t addr)
+mlx4_mr_create_secondary(struct rte_eth_dev *dev, struct mlx4_mr_cache *entry,
+			 uintptr_t addr)
+{
+	struct mlx4_priv *priv = dev->data->dev_private;
+	int ret;
+
+	DEBUG("port %u requesting MR creation for address (%p)",
+	      dev->data->port_id, (void *)addr);
+	ret = mlx4_mp_req_mr_create(dev, addr);
+	if (ret) {
+		DEBUG("port %u fail to request MR creation for address (%p)",
+		      dev->data->port_id, (void *)addr);
+		return UINT32_MAX;
+	}
+	rte_rwlock_read_lock(&priv->mr.rwlock);
+	/* Fill in output data. */
+	mr_lookup_dev(dev, entry, addr);
+	/* Lookup can't fail. */
+	assert(entry->lkey != UINT32_MAX);
+	rte_rwlock_read_unlock(&priv->mr.rwlock);
+	DEBUG("port %u MR CREATED by primary process for %p:\n"
+	      "  [0x%" PRIxPTR ", 0x%" PRIxPTR "), lkey=0x%x",
+	      dev->data->port_id, (void *)addr,
+	      entry->start, entry->end, entry->lkey);
+	return entry->lkey;
+}
+
+/**
+ * Create a new global Memroy Region (MR) for a missing virtual address.
+ * Register entire virtually contiguous memory chunk around the address.
+ * This must be called from the primary process.
+ *
+ * @param dev
+ *   Pointer to Ethernet device.
+ * @param[out] entry
+ *   Pointer to returning MR cache entry, found in the global cache or newly
+ *   created. If failed to create one, this will not be updated.
+ * @param addr
+ *   Target virtual address to register.
+ *
+ * @return
+ *   Searched LKey on success, UINT32_MAX on failure and rte_errno is set.
+ */
+uint32_t
+mlx4_mr_create_primary(struct rte_eth_dev *dev, struct mlx4_mr_cache *entry,
+		       uintptr_t addr)
 {
 	struct mlx4_priv *priv = dev->data->dev_private;
 	struct rte_mem_config *mcfg = rte_eal_get_configuration()->mem_config;
@@ -563,14 +610,6 @@ mlx4_mr_create(struct rte_eth_dev *dev, struct mlx4_mr_cache *entry,
 
 	DEBUG("port %u creating a MR using address (%p)",
 	      dev->data->port_id, (void *)addr);
-	if (rte_eal_process_type() != RTE_PROC_PRIMARY) {
-		WARN("port %u using address (%p) of unregistered mempool"
-		     " in secondary process, please create mempool"
-		     " before rte_eth_dev_start()",
-		     dev->data->port_id, (void *)addr);
-		rte_errno = EPERM;
-		goto err_nolock;
-	}
 	/*
 	 * Release detached MRs if any. This can't be called with holding either
 	 * memory_hotplug_lock or priv->mr.rwlock. MRs on the free list have
@@ -780,6 +819,40 @@ mlx4_mr_create(struct rte_eth_dev *dev, struct mlx4_mr_cache *entry,
 	return UINT32_MAX;
 }
 
+/**
+ * Create a new global Memroy Region (MR) for a missing virtual address.
+ * This can be called from primary and secondary process.
+ *
+ * @param dev
+ *   Pointer to Ethernet device.
+ * @param[out] entry
+ *   Pointer to returning MR cache entry, found in the global cache or newly
+ *   created. If failed to create one, this will not be updated.
+ * @param addr
+ *   Target virtual address to register.
+ *
+ * @return
+ *   Searched LKey on success, UINT32_MAX on failure and rte_errno is set.
+ */
+static uint32_t
+mlx4_mr_create(struct rte_eth_dev *dev, struct mlx4_mr_cache *entry,
+	       uintptr_t addr)
+{
+	uint32_t ret = 0;
+
+	switch (rte_eal_process_type()) {
+	case RTE_PROC_PRIMARY:
+		ret = mlx4_mr_create_primary(dev, entry, addr);
+		break;
+	case RTE_PROC_SECONDARY:
+		ret = mlx4_mr_create_secondary(dev, entry, addr);
+		break;
+	default:
+		break;
+	}
+	return ret;
+}
+
 /**
  * Rebuild the global B-tree cache of device from the original MR list.
  *

drivers/net/mlx4/mlx4_mr.h

@@ -75,6 +75,8 @@ extern rte_rwlock_t mlx4_mem_event_rwlock;
 int mlx4_mr_btree_init(struct mlx4_mr_btree *bt, int n, int socket);
 void mlx4_mr_btree_free(struct mlx4_mr_btree *bt);
 void mlx4_mr_btree_dump(struct mlx4_mr_btree *bt);
+uint32_t mlx4_mr_create_primary(struct rte_eth_dev *dev,
+				struct mlx4_mr_cache *entry, uintptr_t addr);
 void mlx4_mr_mem_event_cb(enum rte_mem_event event_type, const void *addr,
 			  size_t len, void *arg);
 int mlx4_mr_update_mp(struct rte_eth_dev *dev, struct mlx4_mr_ctrl *mr_ctrl,