d4r: official NVIDIA DLSS on AMD GPUs under Linux and Proton

tools/d4r_nvapi_identity.c

@@ -0,0 +1,81 @@
+// Opt-in NVAPI identity bridge for OptiScaler's NVIDIA-only DLSS backend.
+// All NVAPI interfaces except the version string are forwarded to the
+// prefix-local DXVK-NVAPI DLL. The underlying GPU and DLSS execution remain
+// AMD/ZLUDA; this only lets OptiScaler select its official-DLSS route.
+#include <windows.h>
+#include <string.h>
+
+#define NVAPI_GET_INTERFACE_VERSION_STRING 0x01053fa5u
+#define NVAPI_INITIALIZE 0x0150e828u
+#define NVAPI_UNLOAD 0xd22bdd7eu
+
+typedef void *(__cdecl *NvapiQueryInterface)(unsigned int);
+static NvapiQueryInterface real_query;
+static volatile LONG spoof_probe_armed;
+static volatile LONG spoof_probe_used;
+static volatile LONG spoof_unload_armed;
+
+static NvapiQueryInterface load_real_query(void)
+{
+    if (real_query != NULL)
+        return real_query;
+
+    wchar_t path[MAX_PATH];
+    UINT length = GetSystemDirectoryW(path, MAX_PATH);
+    static const wchar_t suffix[] = L"\\d4r_nvapi64_real.dll";
+    if (length == 0 || length + (sizeof(suffix) / sizeof(suffix[0])) > MAX_PATH)
+        return NULL;
+    memcpy(path + length, suffix, sizeof(suffix));
+
+    HMODULE module = LoadLibraryW(path);
+    if (module == NULL)
+        return NULL;
+    FARPROC symbol = GetProcAddress(module, "nvapi_QueryInterface");
+    memcpy(&real_query, &symbol, sizeof(real_query));
+    return real_query;
+}
+
+static int __cdecl d4r_get_interface_version_string(char *description)
+{
+    if (description == NULL)
+        return -5; // NVAPI_INVALID_ARGUMENT
+    // OptiScaler takes the real-NVIDIA branch for any non-DXVK version string.
+    // NVAPI's short string has 64 bytes.
+    static const char identity[] = "NVIDIA NVAPI (d4r compatibility)";
+    memcpy(description, identity, sizeof(identity));
+    if (InterlockedCompareExchange(&spoof_probe_used, 0, 0) == 0)
+        InterlockedExchange(&spoof_probe_armed, 1);
+    return 0; // NVAPI_OK
+}
+
+static int __cdecl d4r_initialize_identity_probe(void)
+{
+    // OptiScaler calls this inside DLL_PROCESS_ATTACH when it believes it is
+    // loading NVIDIA's own NVAPI. DXVK-NVAPI initializes DXGI here, which is
+    // unsafe under the loader lock. The later, ordinary init calls are passed
+    // through to DXVK-NVAPI.
+    InterlockedExchange(&spoof_probe_used, 1);
+    InterlockedExchange(&spoof_unload_armed, 1);
+    return 0;
+}
+
+static int __cdecl d4r_unload_identity_probe(void)
+{
+    return 0;
+}
+
+__declspec(dllexport) void *__cdecl nvapi_QueryInterface(unsigned int interface_id)
+{
+    NvapiQueryInterface query = load_real_query();
+    if (query == NULL)
+        return NULL;
+    if (interface_id == NVAPI_GET_INTERFACE_VERSION_STRING)
+        return (void *)&d4r_get_interface_version_string;
+    if (interface_id == NVAPI_INITIALIZE &&
+        InterlockedCompareExchange(&spoof_probe_armed, 0, 1) == 1)
+        return (void *)&d4r_initialize_identity_probe;
+    if (interface_id == NVAPI_UNLOAD &&
+        InterlockedCompareExchange(&spoof_unload_armed, 0, 1) == 1)
+        return (void *)&d4r_unload_identity_probe;
+    return query(interface_id);
+}