reading the cpu frequncy fromregistry in kernel

Question

hello im trying to read the cpu freq from the registry am i doing correct ?

__int64 getCPUFrequencyFromRegistryA()
{
	NTSTATUS status;
	OBJECT_ATTRIBUTES objAttributes;
	UNICODE_STRING keyPath = RTL_CONSTANT_STRING(L"\\Registry\\Machine\\HARDWARE\\DESCRIPTION\\System\\CentralProcessor\\0");
	HANDLE hKey;

	InitializeObjectAttributes(&objAttributes, &keyPath, OBJ_CASE_INSENSITIVE, NULL, NULL);

	status = ZwOpenKey(&hKey, KEY_QUERY_VALUE | KEY_WOW64_64KEY, &objAttributes);
	if (NT_SUCCESS(status))
	{
		UNICODE_STRING valueName = RTL_CONSTANT_STRING(L"~MHz");

		// Allocate a larger buffer for the KEY_VALUE_PARTIAL_INFORMATION structure
		UCHAR buffer[sizeof(KEY_VALUE_PARTIAL_INFORMATION) + sizeof(DWORD)];
		PKEY_VALUE_PARTIAL_INFORMATION kvpi = (PKEY_VALUE_PARTIAL_INFORMATION)buffer;
		ULONG resultLength;

		status = ZwQueryValueKey(hKey, &valueName, KeyValuePartialInformation, kvpi, sizeof(buffer), &resultLength);
		if (NT_SUCCESS(status))
		{
			DWORD frequency = *(PDWORD)(kvpi->Data);

			// Check the status of ZwClose(hKey) and handle potential errors
			status = ZwClose(hKey);
			if (!NT_SUCCESS(status)) {
				// Handle error
			}

			return (__int64)frequency * 1000000; // Multiply by 1,000,000 to get the frequency in Hz.
		}
	}

	status = ZwClose(hKey);
	if (!NT_SUCCESS(status)) {
		// Handle error
	}

	return 0;
}

Answer 1

You can find similar code on GitHub, like :

https://github.com/zenedge/openonload/blob/6e8ea3dfff2b11cb881703de55951a4c69af5a02/src/lib/citools/drv_get_cpu_khz.c#L51