[offload][OpenMP] Require CUDA 11.8 (llvm#191100)

Author: kevinsala

offload/CMakeLists.txt

@@ -4,6 +4,10 @@
 cmake_minimum_required(VERSION 3.20.0)
 set(LLVM_SUBPROJECT_TITLE "liboffload")
 
+# The minimum versions required for dependencies.
+set(OFFLOAD_MIN_CUDA_VERSION 11.8.0)
+set(OFFLOAD_MIN_CUDA_VERSION_CODE 11080)
+
 # Check that the library can actually be built.
 if(APPLE OR WIN32 OR WASM)
   message(WARNING "libomptarget cannot be built on Windows and MacOS X!")

offload/plugins-nextgen/cuda/CMakeLists.txt

@@ -3,7 +3,11 @@ add_target_library(omptarget.rtl.cuda CUDA)
 
 target_sources(omptarget.rtl.cuda PRIVATE src/rtl.cpp)
 
-find_package(CUDAToolkit QUIET)
+# Define the minimum CUDA version required by offload.
+target_compile_definitions(omptarget.rtl.cuda PRIVATE OFFLOAD_MIN_CUDA_VERSION=${OFFLOAD_MIN_CUDA_VERSION_CODE})
+
+find_package(CUDAToolkit QUIET ${OFFLOAD_MIN_CUDA_VERSION})
+
 if(CUDAToolkit_FOUND AND NOT "cuda" IN_LIST LIBOMPTARGET_DLOPEN_PLUGINS)
   message(STATUS "Building CUDA plugin linked against libcuda")
   target_link_libraries(omptarget.rtl.cuda PRIVATE CUDA::cuda_driver)

offload/plugins-nextgen/cuda/src/rtl.cpp

@@ -34,6 +34,11 @@
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Program.h"
 
+// This macro should be defined by the build system.
+#ifndef OFFLOAD_MIN_CUDA_VERSION
+#error "Missing OFFLOAD_MIN_CUDA_VERSION macro"
+#endif
+
 using namespace llvm::offload::debug;
 using namespace error;
 
@@ -1594,6 +1599,22 @@ struct CUDAPluginTy final : public GenericPluginTy {
     if (auto Err = Plugin::check(Res, "error in cuInit: %s"))
       return std::move(Err);
 
+    // Get the latest CUDA version supported by the driver.
+    int Version;
+    Res = cuDriverGetVersion(&Version);
+    if (auto Err = Plugin::check(Res, "error in cuDriverGetVersion: %s"))
+      return std::move(Err);
+
+    // Verify that the driver supports the minimum CUDA version required.
+    constexpr int MinVersion = OFFLOAD_MIN_CUDA_VERSION;
+    if (Version < MinVersion) {
+      ODBG(OLDT_Init) << "Minimum CUDA version not supported by the driver.";
+      return Plugin::error(
+          ErrorCode::UNSUPPORTED,
+          "CUDA driver does not support minimum CUDA version %d (%d detected)",
+          MinVersion, Version);
+    }
+
     // Get the number of devices.
     int NumDevices;
     Res = cuDeviceGetCount(&NumDevices);

offload/test/CMakeLists.txt

@@ -16,7 +16,7 @@ endif()
 # char into the lit command.
 string(REPLACE " " ";" LIBOMPTARGET_LIT_ARG_LIST "${LIBOMPTARGET_LIT_ARGS}")
 
-find_package(CUDAToolkit QUIET)
+find_package(CUDAToolkit QUIET ${OFFLOAD_MIN_CUDA_VERSION})
 if(CUDAToolkit_FOUND)
   get_filename_component(CUDA_ROOT "${CUDAToolkit_BIN_DIR}" DIRECTORY ABSOLUTE)
   get_filename_component(CUDA_LIBDIR "${CUDA_cudart_static_LIBRARY}" DIRECTORY)

offload/unittests/CMakeLists.txt

@@ -26,7 +26,7 @@ function(add_offload_test_device_code test_filename test_name)
 
   # Try to build with support for NVPTX devices.
   if("cuda" IN_LIST LIBOMPTARGET_PLUGINS_TO_BUILD)
-    find_package(CUDAToolkit QUIET)
+    find_package(CUDAToolkit QUIET ${OFFLOAD_MIN_CUDA_VERSION})
     if(CUDAToolkit_FOUND)
       get_filename_component(cuda_path "${CUDAToolkit_BIN_DIR}" DIRECTORY ABSOLUTE)
     endif()

openmp/docs/Building.md

@@ -20,11 +20,12 @@ for those requirements.
 ### Requirements for Building with Nvidia GPU support
 
 The CUDA SDK is required on the machine that will build and execute the
-offloading application. Normally this is only required at runtime by dynamically
-opening the CUDA driver API. This can be disabled in the build by omitting
-`cuda` from the [`LIBOMPTARGET_DLOPEN_PLUGINS`](LIBOMPTARGET_DLOPEN_PLUGINS)
-list which is present by default. With this setting we will instead find the
-CUDA library at LLVM build time and link against it directly.
+offloading application. The CUDA driver must support CUDA 11.8.0 or later.
+Normally this is only required at runtime when the CUDA driver API is
+dynamically opened. This can be disabled in the build by omitting `cuda` from
+the [`LIBOMPTARGET_DLOPEN_PLUGINS`](LIBOMPTARGET_DLOPEN_PLUGINS) list which is
+present by default. With this setting we will instead find the CUDA library at
+LLVM build time and link against it directly.
 
 
 ### Requirements for Building with AMD GPU support