mtl/ofi: use libfabric 1.18 API if available

This patch try to use 1.18 API when it is available. This is because
1.18 API clearly define provider's CUDA API behavior to be that
provider can call CUDA API by default if application uses 1.18 API.

When using older version of API, some libfabric will not claim
support of FI_HMEM even if it is capable of supporting because
the provider does not know whether CUDA calls are permitted.

Signed-off-by: Wei Zhang <wzam@amazon.com>

Author: wzamazon

ompi/mca/mtl/ofi/mtl_ofi_component.c

@@ -560,7 +560,7 @@ ompi_mtl_ofi_component_init(bool enable_progress_threads,
                             bool enable_mpi_threads,
                             bool *accelerator_support)
 {
-    int ret, fi_version;
+    int ret, fi_primary_version, fi_alternate_version;
     int num_local_ranks, sep_support_in_provider, max_ofi_ctxts;
     int ofi_tag_leading_zeros, ofi_tag_bits_for_cid;
     char **include_list = NULL;
@@ -595,8 +595,17 @@ ompi_mtl_ofi_component_init(bool enable_progress_threads,
      * (FI_REMOTE_COMM), which is insufficient for MTL selection.
      *
      * Note: API version 1.9 is the first version that supports FI_HMEM
+     *
+     * Note: API version 1.18 is the first version that clearly define
+     * provider's behavior in making CUDA API calls that all provider
+     * by default is permitted to make CUDA calls if application uses >= 1.18 API.
+     *
+     * If application is using < 1.18 API, some provider will not claim support
+     * of FI_HMEM (even if they are capable of) because it does not know
+     * whether application permits it to make CUDA calls.
      */
-    fi_version = FI_VERSION(1, 9);
+    fi_primary_version = FI_VERSION(1, 18);
+    fi_alternate_version = FI_VERSION(1, 9);
 
     /**
      * Hints to filter providers
@@ -695,7 +704,11 @@ ompi_mtl_ofi_component_init(bool enable_progress_threads,
         hints_dup->caps &= ~(FI_LOCAL_COMM | FI_REMOTE_COMM);
         hints_dup->fabric_attr->prov_name = strdup("efa");
 
-        ret = fi_getinfo(fi_version, NULL, NULL, 0ULL, hints_dup, &providers);
+        ret = fi_getinfo(fi_primary_version, NULL, NULL, 0ULL, hints_dup, &providers);
+        if (FI_ENOSYS == -ret) {
+            /* libfabric is not new enough, fallback to use older version of API */
+           ret = fi_getinfo(fi_alternate_version, NULL, NULL, 0ULL, hints_dup, &providers);
+	}
 
         opal_output_verbose(1, opal_common_ofi.output,
                             "%s:%d: EFA specific fi_getinfo(): %s\n",
@@ -727,12 +740,15 @@ ompi_mtl_ofi_component_init(bool enable_progress_threads,
      * remote node or service.  this does not necessarily allocate resources.
      * Pass NULL for name/service because we want a list of providers supported.
      */
-    ret = fi_getinfo(fi_version,    /* OFI version requested                    */
+    ret = fi_getinfo(fi_primary_version,    /* OFI version requested            */
                      NULL,          /* Optional name or fabric to resolve       */
                      NULL,          /* Optional service name or port to request */
                      0ULL,          /* Optional flag                            */
                      hints,         /* In: Hints to filter providers            */
                      &providers);   /* Out: List of matching providers          */
+    if (FI_ENOSYS == -ret) {
+        ret = fi_getinfo(fi_alternate_version, NULL, NULL, 0ULL, hints, &providers);
+    }
 
     opal_output_verbose(1, opal_common_ofi.output,
                         "%s:%d: fi_getinfo(): %s\n",