diff --git a/vllm/attention/layer.py b/vllm/attention/layer.py
index 962c45a65ae23..c210292865b29 100644
--- a/vllm/attention/layer.py
+++ b/vllm/attention/layer.py
@@ -148,9 +148,13 @@ def forward(
         kv_cache: torch.Tensor,
         attn_metadata: AttentionMetadata,
     ) -> torch.Tensor:
-        if self.calculate_kv_scales and \
-            attn_metadata.enable_kv_scales_calculation:
-            self.calc_kv_scales(key, value)
+        # NOTE: please avoid accessing `kv_cache` and `attn_metadata` arguments
+        # directly, use `self.kv_cache` and
+        # `get_forward_context().attn_metadata` instead.
+        if self.calculate_kv_scales:
+            ctx_attn_metadata = get_forward_context().attn_metadata
+            if ctx_attn_metadata.enable_kv_scales_calculation:
+                self.calc_kv_scales(key, value)
         if self.use_output:
             output = torch.empty_like(query)
             hidden_size = query.size(-1)
@@ -164,15 +168,27 @@ def forward(
             if value is not None:
                 value = value.view(-1, self.num_kv_heads, self.head_size)
             if self.use_direct_call:
-                unified_attention_with_output(query, key, value, output,
-                                              self.layer_name)
+                forward_context: ForwardContext = get_forward_context()
+                ctx_attn_metadata = forward_context.attn_metadata
+                self_kv_cache = self.kv_cache[forward_context.virtual_engine]
+                self.impl.forward(self,
+                                  query,
+                                  key,
+                                  value,
+                                  self_kv_cache,
+                                  ctx_attn_metadata,
+                                  output=output)
             else:
                 torch.ops.vllm.unified_attention_with_output(
                     query, key, value, output, self.layer_name)
             return output.view(-1, hidden_size)
         else:
             if self.use_direct_call:
-                return unified_attention(query, key, value, self.layer_name)
+                forward_context = get_forward_context()
+                ctx_attn_metadata = forward_context.attn_metadata
+                self_kv_cache = self.kv_cache[forward_context.virtual_engine]
+                return self.impl.forward(self, query, key, value,
+                                         self_kv_cache, ctx_attn_metadata)
             else:
                 return torch.ops.vllm.unified_attention(
                     query, key, value, self.layer_name)