Check if bitblas is installed during support check (#17572)

Signed-off-by: mgoin <mgoin64@gmail.com>

vllm/model_executor/layers/quantization/utils/bitblas_utils.py

@@ -71,6 +71,15 @@ def _check_bitblas_supported(
                 f"Only group_sizes = {BITBLAS_SUPPORTED_GROUP_SIZES} "
                 "are supported.")
 
+    # Finally, check if bitblas is installed
+    try:
+        import bitblas
+        if bitblas.__version__ < MINIMUM_BITBLAS_VERSION:
+            raise ImportError("bitblas version is wrong. Please "
+                              f"install bitblas>={MINIMUM_BITBLAS_VERSION}")
+    except ImportError:
+        return False, "BitBLAS is not installed."
+
     return True, None