In order to get E-Switch vport identifiers the mlx5 PMD relies
on two approaches:
  - use port query API if it is provided by rdma-core library
  - otherwise, deduce vport ids from the related VF index
The latter is not reliable and may not work with newer kernel
driver versions and in some configurations (LAG), causing
the E-Switch malfunction. Hence, engaging the port query API
is highly desirable.

The port attributes query API was supported by vendor rdma-core
versions only (in OFED). In Upstream, the rdma-core mlx5 provider
introduced the port attributes query API since version v35.0 - the
mlx5dv_query_port routine, that differs from vendor API. In order
to support this change in the rdma-core the conditional compilation
flag HAVE_MLX5DV_DR_DEVX_PORT_V35 is introduced by the this patch.

In the OFED rdma-core version the new compatible mlx5dv_query_port
routine was introduced as well, replacing the existing proprietary
mlx5dv_query_devx_port routine. The proprietary routine is still
controlled in PMD code with HAVE_MLX5DV_DR_DEVX_PORT conditional
flag.

Currently, the OFED rdma-core library contains both versions of
port query API. And this version is a transitional one, there are
the plans to remove the proprietary mlx5dv_query_devx_port routine
and the HAVE_MLX5DV_DR_DEVX_PORT flag in PMD will not work anymore.

With this patch applied the mlx5 PMD can be compiled and operates
over all rdma-core versions:
  - Upstream rdma-core before v35 (deduces vport id from VF name)
                           (* E-Switch may not operate correctly)
  - Upstream rdma-core v35 and above (uses common port query API)
  - rdma-core OFED before 5.5 (uses proprietary port query API)
  - rdma-core OFED 5.5 and above (uses common port query API)

Despite this patch is not a bugfix (it follows the introduced API
variation in underlying library), it covers the major compatibility
issue and is highly desired to be ported to DPDK LTS.

Cc: sta...@dpdk.org

Signed-off-by: Viacheslav Ovsiienko <viachesl...@nvidia.com>
Acked-by: Matan Azrad <ma...@nvidia.com>

---
v1: 
http://patches.dpdk.org/project/dpdk/patch/20210607093726.14546-1-viachesl...@nvidia.com/
v2: 
http://patches.dpdk.org/project/dpdk/patch/20210619124830.25297-1-viachesl...@nvidia.com/#134196
    - commit message was clarified
v3: - reword commit message addressing comments
    - split patch into small series

---
 drivers/common/mlx5/linux/meson.build |  2 +
 drivers/common/mlx5/linux/mlx5_glue.c | 55 ++++++++++++++++++++----
 drivers/common/mlx5/linux/mlx5_glue.h | 16 ++++++-
 drivers/net/mlx5/linux/mlx5_os.c      | 60 ++++++++++++---------------
 4 files changed, 89 insertions(+), 44 deletions(-)

diff --git a/drivers/common/mlx5/linux/meson.build 
b/drivers/common/mlx5/linux/meson.build
index 007834a49b..5a0ee51b37 100644
--- a/drivers/common/mlx5/linux/meson.build
+++ b/drivers/common/mlx5/linux/meson.build
@@ -93,6 +93,8 @@ has_sym_args = [
             'IBV_WQ_FLAG_RX_END_PADDING' ],
         [ 'HAVE_MLX5DV_DR_DEVX_PORT', 'infiniband/mlx5dv.h',
             'mlx5dv_query_devx_port' ],
+       [ 'HAVE_MLX5DV_DR_DEVX_PORT_V35', 'infiniband/mlx5dv.h',
+           'mlx5dv_query_port' ],
         [ 'HAVE_IBV_DEVX_OBJ', 'infiniband/mlx5dv.h',
             'mlx5dv_devx_obj_create' ],
         [ 'HAVE_IBV_FLOW_DEVX_COUNTERS', 'infiniband/mlx5dv.h',
diff --git a/drivers/common/mlx5/linux/mlx5_glue.c 
b/drivers/common/mlx5/linux/mlx5_glue.c
index d3bd645a5b..38b174aa31 100644
--- a/drivers/common/mlx5/linux/mlx5_glue.c
+++ b/drivers/common/mlx5/linux/mlx5_glue.c
@@ -1087,17 +1087,54 @@ mlx5_glue_devx_wq_query(struct ibv_wq *wq, const void 
*in, size_t inlen,
 static int
 mlx5_glue_devx_port_query(struct ibv_context *ctx,
                          uint32_t port_num,
-                         struct mlx5dv_devx_port *mlx5_devx_port)
-{
+                         struct mlx5_port_info *info)
+{
+       int err = 0;
+
+       info->query_flags = 0;
+#ifdef HAVE_MLX5DV_DR_DEVX_PORT_V35
+       /* The DevX port query API is implemented (rdma-core v35 and above). */
+       struct mlx5_ib_uapi_query_port devx_port;
+
+       memset(&devx_port, 0, sizeof(devx_port));
+       err = mlx5dv_query_port(ctx, port_num, &devx_port);
+       if (err)
+               return err;
+       if (devx_port.flags & MLX5DV_QUERY_PORT_VPORT_REG_C0) {
+               info->vport_meta_tag = devx_port.reg_c0.value;
+               info->vport_meta_mask = devx_port.reg_c0.mask;
+               info->query_flags |= MLX5_PORT_QUERY_REG_C0;
+       }
+       if (devx_port.flags & MLX5DV_QUERY_PORT_VPORT) {
+               info->vport_id = devx_port.vport;
+               info->query_flags |= MLX5_PORT_QUERY_VPORT;
+       }
+#else
 #ifdef HAVE_MLX5DV_DR_DEVX_PORT
-       return mlx5dv_query_devx_port(ctx, port_num, mlx5_devx_port);
+       /* The legacy DevX port query API is implemented (prior v35). */
+       struct mlx5dv_devx_port devx_port = {
+               .comp_mask = MLX5DV_DEVX_PORT_VPORT |
+                            MLX5DV_DEVX_PORT_MATCH_REG_C_0
+       };
+
+       err = mlx5dv_query_devx_port(ctx, port_num, &devx_port);
+       if (err)
+               return err;
+       if (devx_port.comp_mask & MLX5DV_DEVX_PORT_MATCH_REG_C_0) {
+               info->vport_meta_tag = devx_port.reg_c_0.value;
+               info->vport_meta_mask = devx_port.reg_c_0.mask;
+               info->query_flags |= MLX5_PORT_QUERY_REG_C0;
+       }
+       if (devx_port.comp_mask & MLX5DV_DEVX_PORT_VPORT) {
+               info->vport_id = devx_port.vport_num;
+               info->query_flags |= MLX5_PORT_QUERY_VPORT;
+       }
 #else
-       (void)ctx;
-       (void)port_num;
-       (void)mlx5_devx_port;
-       errno = ENOTSUP;
-       return errno;
-#endif
+       RTE_SET_USED(ctx);
+       RTE_SET_USED(port_num);
+#endif /* HAVE_MLX5DV_DR_DEVX_PORT */
+#endif /* HAVE_MLX5DV_DR_DEVX_PORT_V35 */
+       return err;
 }
 
 static int
diff --git a/drivers/common/mlx5/linux/mlx5_glue.h 
b/drivers/common/mlx5/linux/mlx5_glue.h
index 97462e9ab8..840d8cf57f 100644
--- a/drivers/common/mlx5/linux/mlx5_glue.h
+++ b/drivers/common/mlx5/linux/mlx5_glue.h
@@ -84,6 +84,20 @@ struct mlx5dv_dr_action;
 struct mlx5dv_devx_port;
 #endif
 
+#ifndef HAVE_MLX5DV_DR_DEVX_PORT_V35
+struct mlx5dv_port;
+#endif
+
+#define MLX5_PORT_QUERY_VPORT (1u << 0)
+#define MLX5_PORT_QUERY_REG_C0 (1u << 1)
+
+struct mlx5_port_info {
+       uint16_t query_flags;
+       uint16_t vport_id; /* Associated VF vport index (if any). */
+       uint32_t vport_meta_tag; /* Used for vport index match ove VF LAG. */
+       uint32_t vport_meta_mask; /* Used for vport index field match mask. */
+};
+
 #ifndef HAVE_MLX5_DR_CREATE_ACTION_FLOW_METER
 struct mlx5dv_dr_flow_meter_attr;
 #endif
@@ -311,7 +325,7 @@ struct mlx5_glue {
                             void *out, size_t outlen);
        int (*devx_port_query)(struct ibv_context *ctx,
                               uint32_t port_num,
-                              struct mlx5dv_devx_port *mlx5_devx_port);
+                              struct mlx5_port_info *info);
        int (*dr_dump_domain)(FILE *file, void *domain);
        int (*dr_dump_rule)(FILE *file, void *rule);
        int (*devx_query_eqn)(struct ibv_context *context, uint32_t cpus,
diff --git a/drivers/net/mlx5/linux/mlx5_os.c b/drivers/net/mlx5/linux/mlx5_os.c
index 302a881310..92b3009786 100644
--- a/drivers/net/mlx5/linux/mlx5_os.c
+++ b/drivers/net/mlx5/linux/mlx5_os.c
@@ -822,9 +822,7 @@ mlx5_dev_spawn(struct rte_device *dpdk_dev,
        char name[RTE_ETH_NAME_MAX_LEN];
        int own_domain_id = 0;
        uint16_t port_id;
-#ifdef HAVE_MLX5DV_DR_DEVX_PORT
-       struct mlx5dv_devx_port devx_port = { .comp_mask = 0 };
-#endif
+       struct mlx5_port_info vport_info = { .query_flags = 0 };
 
        /* Determine if this port representor is supposed to be spawned. */
        if (switch_info->representor && dpdk_dev->devargs &&
@@ -1055,29 +1053,27 @@ mlx5_dev_spawn(struct rte_device *dpdk_dev,
        priv->vport_meta_tag = 0;
        priv->vport_meta_mask = 0;
        priv->pf_bond = spawn->pf_bond;
-#ifdef HAVE_MLX5DV_DR_DEVX_PORT
        /*
-        * The DevX port query API is implemented. E-Switch may use
-        * either vport or reg_c[0] metadata register to match on
-        * vport index. The engaged part of metadata register is
-        * defined by mask.
+        * If we have E-Switch we should determine the vport attributes.
+        * E-Switch may use either source vport field or reg_c[0] metadata
+        * register to match on vport index. The engaged part of metadata
+        * register is defined by mask.
         */
        if (switch_info->representor || switch_info->master) {
-               devx_port.comp_mask = MLX5DV_DEVX_PORT_VPORT |
-                                     MLX5DV_DEVX_PORT_MATCH_REG_C_0;
-               err = mlx5_glue->devx_port_query(sh->ctx, spawn->phys_port,
-                                                &devx_port);
+               err = mlx5_glue->devx_port_query(sh->ctx,
+                                                spawn->phys_port,
+                                                &vport_info);
                if (err) {
                        DRV_LOG(WARNING,
                                "can't query devx port %d on device %s",
                                spawn->phys_port,
                                mlx5_os_get_dev_device_name(spawn->phys_dev));
-                       devx_port.comp_mask = 0;
+                       vport_info.query_flags = 0;
                }
        }
-       if (devx_port.comp_mask & MLX5DV_DEVX_PORT_MATCH_REG_C_0) {
-               priv->vport_meta_tag = devx_port.reg_c_0.value;
-               priv->vport_meta_mask = devx_port.reg_c_0.mask;
+       if (vport_info.query_flags & MLX5_PORT_QUERY_REG_C0) {
+               priv->vport_meta_tag = vport_info.vport_meta_tag;
+               priv->vport_meta_mask = vport_info.vport_meta_mask;
                if (!priv->vport_meta_mask) {
                        DRV_LOG(ERR, "vport zero mask for port %d"
                                     " on bonding device %s",
@@ -1097,8 +1093,8 @@ mlx5_dev_spawn(struct rte_device *dpdk_dev,
                        goto error;
                }
        }
-       if (devx_port.comp_mask & MLX5DV_DEVX_PORT_VPORT) {
-               priv->vport_id = devx_port.vport_num;
+       if (vport_info.query_flags & MLX5_PORT_QUERY_VPORT) {
+               priv->vport_id = vport_info.vport_id;
        } else if (spawn->pf_bond >= 0 &&
                   (switch_info->representor || switch_info->master)) {
                DRV_LOG(ERR, "can't deduce vport index for port %d"
@@ -1108,25 +1104,21 @@ mlx5_dev_spawn(struct rte_device *dpdk_dev,
                err = ENOTSUP;
                goto error;
        } else {
-               /* Suppose vport index in compatible way. */
+               /*
+                * Suppose vport index in compatible way. Kernel/rdma_core
+                * support single E-Switch per PF configurations only and
+                * vport_id field contains the vport index for associated VF,
+                * which is deduced from representor port name.
+                * For example, let's have the IB device port 10, it has
+                * attached network device eth0, which has port name attribute
+                * pf0vf2, we can deduce the VF number as 2, and set vport index
+                * as 3 (2+1). This assigning schema should be changed if the
+                * multiple E-Switch instances per PF configurations or/and PCI
+                * subfunctions are added.
+                */
                priv->vport_id = switch_info->representor ?
                                 switch_info->port_name + 1 : -1;
        }
-#else
-       /*
-        * Kernel/rdma_core support single E-Switch per PF configurations
-        * only and vport_id field contains the vport index for
-        * associated VF, which is deduced from representor port name.
-        * For example, let's have the IB device port 10, it has
-        * attached network device eth0, which has port name attribute
-        * pf0vf2, we can deduce the VF number as 2, and set vport index
-        * as 3 (2+1). This assigning schema should be changed if the
-        * multiple E-Switch instances per PF configurations or/and PCI
-        * subfunctions are added.
-        */
-       priv->vport_id = switch_info->representor ?
-                        switch_info->port_name + 1 : -1;
-#endif
        priv->representor_id = mlx5_representor_id_encode(switch_info,
                                                          eth_da->type);
        /*
-- 
2.18.1

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