CUDA: Enhance MPIX_Query_cuda_support() with runtime support check

Signed-off-by: Devendar Bureddy <devendar@mellanox.com>
(cherry picked from commit b2cc985)

Author: bureddy

ompi/mpiext/cuda/c/MPIX_Query_cuda_support.3in

@@ -24,8 +24,33 @@ There is no C++ binding for this function.
 .SH DESCRIPTION
 .ft R
 
+This routine return 1 if MPI library is build with CUDA and runtime supports CUDA buffers.
+This routine must be called after MPI is initialized by a call to MPI_Init or MPI_Init_thread.
+
 .SH Examples
 .ft R
+.nf
+
+#include <stdio.h>
+#include "mpi.h"
+
+#include "mpi-ext.h" /* Needed for CUDA-aware check */
+
+int main(int argc, char *argv[])
+{
+
+    MPI_Init(&argc, &argv);
+
+    if (MPIX_Query_cuda_support()) {
+        printf("This MPI library has CUDA-aware support.\n");
+    } else {
+        printf("This MPI library does not have CUDA-aware support.\n");
+    }
+    MPI_Finalize();
+
+    return 0;
+}
+.fi
 
 .SH See Also
 .ft R

ompi/mpiext/cuda/c/mpiext_cuda.c

@@ -21,11 +21,12 @@
 #include <string.h>
 
 #include "opal/constants.h"
+#include "opal/runtime/opal_params.h"
 #include "ompi/mpiext/cuda/c/mpiext_cuda_c.h"
 
 /* If CUDA-aware support is configured in, return 1. Otherwise, return 0.
  * This API may be extended to return more features in the future. */
 int MPIX_Query_cuda_support(void)
 {
-    return OPAL_CUDA_SUPPORT;
+    return opal_built_with_cuda_support && opal_cuda_runtime_initialized;
 }

opal/mca/common/cuda/common_cuda.c

@@ -456,6 +456,7 @@ int mca_common_cuda_stage_one_init(void)
 #if OPAL_CUDA_GET_ATTRIBUTES
     OPAL_CUDA_DLSYM(libcuda_handle, cuPointerGetAttributes);
 #endif /* OPAL_CUDA_GET_ATTRIBUTES */
+    opal_cuda_runtime_initialized = true;
     return 0;
 }
 

opal/runtime/opal_params.c

@@ -61,6 +61,7 @@ bool opal_timing_overhead = true;
 #endif
 
 bool opal_built_with_cuda_support = OPAL_INT_TO_BOOL(OPAL_CUDA_SUPPORT);
+bool opal_cuda_runtime_initialized = false;
 bool opal_cuda_support = false;
 bool opal_warn_on_missing_libcuda = true;
 

opal/runtime/opal_params.h

@@ -48,6 +48,11 @@ OPAL_DECLSPEC extern bool opal_built_with_cuda_support;
  *   */
 OPAL_DECLSPEC extern bool opal_cuda_support;
 
+/**
+ * Whether cuda runtime support is initialized or not.
+ */
+OPAL_DECLSPEC extern bool opal_cuda_runtime_initialized;
+
 /**
  *  * Whether we want to warn the user when libcuda is missing.
  *   */