From e8830759d41ac2d4ec367059140034b68919de86 Mon Sep 17 00:00:00 2001
From: ShaoChunLee <Shao-Chun.Lee@amd.com>
Date: Fri, 2 Jan 2026 20:42:00 +0000
Subject: [PATCH] fix rope kv_cache for RocmAiterUnifiedAttentionImpl

---
 vllm/model_executor/models/gpt_oss.py         |  2 +-
 .../backends/rocm_aiter_unified_attn.py       | 77 +++++++++++++++----
 2 files changed, 62 insertions(+), 17 deletions(-)

diff --git a/vllm/model_executor/models/gpt_oss.py b/vllm/model_executor/models/gpt_oss.py
index a423d54a3188..c9bf7d11b05c 100644
--- a/vllm/model_executor/models/gpt_oss.py
+++ b/vllm/model_executor/models/gpt_oss.py
@@ -137,7 +137,7 @@ def forward(
         qkv, _ = self.qkv_proj(hidden_states)
         q, k, v = qkv.split([self.q_size, self.kv_size, self.kv_size], dim=-1)
         # q, k = self.rotary_emb(positions, q, k)
-        v = v.contiguous()
+        # v = v.contiguous()
         attn_output = self.attn(q, k, v, positions=positions)
         output, _ = self.o_proj(attn_output)
         return output
diff --git a/vllm/v1/attention/backends/rocm_aiter_unified_attn.py b/vllm/v1/attention/backends/rocm_aiter_unified_attn.py
index 16fb52ab501c..377d10250918 100644
--- a/vllm/v1/attention/backends/rocm_aiter_unified_attn.py
+++ b/vllm/v1/attention/backends/rocm_aiter_unified_attn.py
@@ -7,6 +7,7 @@
 from vllm import _custom_ops as ops
 from vllm.attention.backends.abstract import AttentionType
 from vllm.logger import init_logger
+from vllm.platforms import current_platform
 from vllm.model_executor.layers.quantization.utils.quant_utils import (
     QuantKey,
     kFp8StaticTensorSym,
@@ -20,6 +21,10 @@
 
 logger = init_logger(__name__)
 
+if current_platform.is_rocm():
+    from vllm._aiter_ops import rocm_aiter_ops
+    if rocm_aiter_ops.is_enabled():
+        from aiter.ops.triton.fused_kv_cache import fused_qk_rope_reshape_and_cache
 
 class RocmAiterUnifiedAttentionBackend(RocmAttentionBackend):
     accept_output_buffer: bool = True
@@ -102,6 +107,7 @@ def forward(
         output: torch.Tensor | None = None,
         output_scale: torch.Tensor | None = None,
         output_block_scale: torch.Tensor | None = None,
+        positions: torch.Tensor | None = None,
     ) -> torch.Tensor:
         """Forward pass with FlashAttention.
 
@@ -145,23 +151,62 @@ def forward(
         # key and value may be None in the case of cross attention. They are
         # calculated once based on the output from the encoder and then cached
         # in KV cache.
-        if (
-            self.kv_sharing_target_layer_name is None
-            and key is not None
-            and value is not None
-        ):
-            # Reshape the input keys and values and store them in the cache.
-            # Skip this if sharing KV cache with an earlier attention layer.
-            ops.reshape_and_cache_flash(
-                key,
-                value,
-                key_cache,
-                value_cache,
-                attn_metadata.slot_mapping,
-                self.kv_cache_dtype,
-                layer._k_scale,
-                layer._v_scale,
+
+        if positions is not None and query.shape[0] <= 256 and rocm_aiter_ops.is_enabled():
+            assert self.kv_sharing_target_layer_name is None
+            cos_sin_cache = self.rotary_emb.cos_sin_cache
+            is_neox = self.rotary_emb.is_neox_style
+            cos, sin = cos_sin_cache.chunk(2, dim=-1)
+            is_fp8_kv_cache = self.kv_cache_dtype.startswith("fp8")
+            if is_fp8_kv_cache:
+                key_cache = key_cache.view(current_platform.fp8_dtype())
+                value_cache = value_cache.view(current_platform.fp8_dtype())
+            query, key, key_cache, value_cache, output = (
+                fused_qk_rope_reshape_and_cache(
+                    query,
+                    key,
+                    value,
+                    key_cache,
+                    value_cache,
+                    attn_metadata.slot_mapping,
+                    positions,
+                    cos,
+                    sin,
+                    layer._k_scale,
+                    layer._v_scale,
+                    is_neox,
+                    flash_layout=True,
+                    apply_scale=is_fp8_kv_cache,
+                    offs=None,
+                    q_out=query,
+                    k_out=key,
+                    output_zeros=True,
+                    zeros_out=output,
+                )
             )
+        else:
+            if positions is not None:
+                if current_platform.is_rocm():
+                    query, key = self.rotary_emb.forward_cuda(positions, query, key)
+                else:
+                    query, key = self.rotary_emb(positions, query, key)
+            if (
+                self.kv_sharing_target_layer_name is None
+                and key is not None
+                and value is not None
+            ):
+                # Reshape the input keys and values and store them in the cache.
+                # Skip this if sharing KV cache with an earlier attention layer.
+                ops.reshape_and_cache_flash(
+                    key,
+                    value,
+                    key_cache,
+                    value_cache,
+                    attn_metadata.slot_mapping,
+                    self.kv_cache_dtype,
+                    layer._k_scale,
+                    layer._v_scale,
+                )
 
         if self.kv_cache_dtype.startswith("fp8"):
             key_cache = key_cache.view(self.fp8_dtype)