[Test][Quantization] Gate CUTLASS W4A8 kernel tests to SM90 (#58878)

Signed-off-by: Kevin Li <kevinbean99@gmail.com>
Co-authored-by: Misha Goin <mgoin64@gmail.com>

tests/kernels/quantization/test_cutlass_w4a8.py

@@ -29,8 +29,11 @@ if not current_platform.is_cuda():
 #  `is_quant_method_supported` conflates kernels with quantization methods
 #  an assumption which is breaking down as quantizations methods can have
 #  have kernels and some kernels support multiple quantization methods.
-capability = current_platform.get_device_capability()
-IS_SUPPORTED_BY_GPU = capability is not None and capability[0] >= 9
+# CUTLASS W4A8 kernels are only built for SM90 (9.0a); the kernel selector
+# requires exactly SM90 too, so match it here rather than accepting >= 90.
+IS_SUPPORTED_BY_GPU = (
+    current_platform.is_cuda() and current_platform.is_device_capability(90)
+)
 
 MNK_SHAPES = [
     (1, 128, 128),
@@ -106,10 +109,6 @@ TEST_TYPES = [
 
 # TODO: in future PR refactor this and `is_quant_method_supported` in the kernel
 #  unit tests to a common utility function. Currently the use of
-#  `is_quant_method_supported` conflates kernels with quantization methods
-#  an assumption which is breaking down as quantizations methods can have
-#  have kernels and some kernels support multiple quantization methods.
-IS_SUPPORTED_BY_GPU = current_platform.has_device_capability(90)
 
 
 # For testing quantized linear kernels

tests/kernels/quantization/test_cutlass_w4a8_moe.py

@@ -17,9 +17,8 @@ from vllm.platforms import current_platform
 from vllm.scalar_type import ScalarType, scalar_types
 from vllm.utils.torch_utils import set_random_seed
 
-capability = current_platform.get_device_capability()
 IS_SUPPORTED_BY_GPU = (
-    current_platform.is_cuda() and capability is not None and capability[0] >= 9
+    current_platform.is_cuda() and current_platform.is_device_capability(90)
 )