nvapi-d3d11: Fix struct version handling

jp7677 · Aug 28, 2024 · be0c8c6 · be0c8c6
1 parent 3a4a4cd
commit be0c8c6
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Showing 2 changed files with 17 additions and 27 deletions.
diff --git a/src/nvapi_d3d11.cpp b/src/nvapi_d3d11.cpp
@@ -69,25 +69,26 @@ extern "C" {
         if (pMultiGPUCaps == nullptr)
             return InvalidArgument(n);
 
-        switch (pMultiGPUCaps->version) {
-            case 0: // NV_MULTIGPU_CAPS_V1 has no version field
-            case NV_MULTIGPU_CAPS_VER1: {
+        auto version = pMultiGPUCaps->version;
+        switch (version) { // NOLINT(*-multiway-paths-covered)
+            case NV_MULTIGPU_CAPS_VER2:
+                *pMultiGPUCaps = {};
+                pMultiGPUCaps->version = version;
+                pMultiGPUCaps->multiGPUVersion = 3; // Observed on Windows
+                pMultiGPUCaps->nTotalGPUs = nvapiAdapterRegistry->GetAdapterCount();
+                // Report on purpose that no SLI GPUs are available by
+                // keeping pMultiGPUCaps->nSLIGPUs at zero
+                break;
+            default: {
+                // NV_MULTIGPU_CAPS_V1 has no version field
                 auto pMultiGPUCapsV1 = reinterpret_cast<NV_MULTIGPU_CAPS_V1*>(pMultiGPUCaps);
                 *pMultiGPUCapsV1 = {};
-                // Report that SLI is not available
+                pMultiGPUCapsV1->reserved = version;  // This is a union field with version in V2
+                pMultiGPUCapsV1->multiGPUVersion = 3; // Observed on Windows
                 pMultiGPUCapsV1->nTotalGPUs = nvapiAdapterRegistry->GetAdapterCount();
-                pMultiGPUCapsV1->nSLIGPUs = 0;
-                break;
-            }
-            case NV_MULTIGPU_CAPS_VER2: {
-                *pMultiGPUCaps = {};
-                // Report that SLI is not available
-                pMultiGPUCaps->nTotalGPUs = nvapiAdapterRegistry->GetAdapterCount();
-                pMultiGPUCaps->nSLIGPUs = 0;
+                // See above about reporting no SLI
                 break;
             }
-            default:
-                return IncompatibleStructVersion(n, pMultiGPUCaps->version);
         }
 
         return Ok(n);

diff --git a/tests/nvapi_d3d11.cpp b/tests/nvapi_d3d11.cpp
@@ -453,6 +453,7 @@ TEST_CASE("D3D11 MultiGPU methods succeed", "[.d3d11]") {
         NV_MULTIGPU_CAPS_V1 multiGPUCaps{};
 
         REQUIRE(NvAPI_D3D11_MultiGPU_GetCaps(reinterpret_cast<PNV_MULTIGPU_CAPS>(&multiGPUCaps)) == NVAPI_OK);
+        REQUIRE(multiGPUCaps.multiGPUVersion == 3);
         REQUIRE(multiGPUCaps.nTotalGPUs == 1);
         REQUIRE(multiGPUCaps.nSLIGPUs == 0);
     }
@@ -462,23 +463,11 @@ TEST_CASE("D3D11 MultiGPU methods succeed", "[.d3d11]") {
         multiGPUCaps.version = NV_MULTIGPU_CAPS_VER2;
 
         REQUIRE(NvAPI_D3D11_MultiGPU_GetCaps(&multiGPUCaps) == NVAPI_OK);
+        REQUIRE(multiGPUCaps.multiGPUVersion == 3);
         REQUIRE(multiGPUCaps.nTotalGPUs == 1);
         REQUIRE(multiGPUCaps.nSLIGPUs == 0);
     }
 
-    SECTION("MultiGPU_GetCaps with unknown struct version returns incompatible-struct-version") {
-        NV_MULTIGPU_CAPS multiGPUCaps{};
-        multiGPUCaps.version = NV_MULTIGPU_CAPS_VER2 + 1;
-        REQUIRE(NvAPI_D3D11_MultiGPU_GetCaps(&multiGPUCaps) == NVAPI_INCOMPATIBLE_STRUCT_VERSION);
-    }
-
-    SECTION("MultiGPU_GetCaps with current struct version returns not incompatible-struct-version") {
-        // This test fails when a header update provides a newer not yet implemented struct version
-        NV_MULTIGPU_CAPS multiGPUCaps{};
-        multiGPUCaps.version = NV_MULTIGPU_CAPS_VER;
-        REQUIRE(NvAPI_D3D11_MultiGPU_GetCaps(&multiGPUCaps) != NVAPI_INCOMPATIBLE_STRUCT_VERSION);
-    }
-
     SECTION("MultiGPU_Init returns OK") {
         REQUIRE(NvAPI_D3D11_MultiGPU_Init(true) == NVAPI_OK);
     }