[ROCm] AITER fused RoPE+KVCache (#33443)

Signed-off-by: Rohan138 <rohanpotdar138@gmail.com>
Signed-off-by: charlifu <charlifu@amd.com>
Signed-off-by: Rohan Potdar <66227218+Rohan138@users.noreply.github.com>
Co-authored-by: charlifu <charlifu@amd.com>
Co-authored-by: Luka Govedič <ProExpertProg@users.noreply.github.com>
Co-authored-by: Douglas Lehr <91553416+dllehr-amd@users.noreply.github.com>

vllm/v1/attention/backends/triton_attn.py

@@ -7,6 +7,7 @@ from typing import ClassVar
 
 import torch
 
+from vllm._aiter_ops import rocm_aiter_ops
 from vllm.config import CUDAGraphMode, VllmConfig
 from vllm.config.cache import CacheDType
 from vllm.logger import init_logger
@@ -596,3 +597,42 @@ class TritonAttentionImpl(AttentionImpl):
             layer._k_scale,
             layer._v_scale,
         )
+
+    def fused_rope_kvcache_supported(self):
+        return rocm_aiter_ops.is_enabled()
+
+    def do_rope_and_kv_cache_update(
+        self,
+        layer: AttentionLayer,
+        query: torch.Tensor,
+        key: torch.Tensor,
+        value: torch.Tensor,
+        positions: torch.Tensor,
+        cos_sin_cache: torch.Tensor,
+        is_neox: bool,
+        kv_cache: torch.Tensor,
+        layer_slot_mapping: torch.Tensor,
+    ):
+        key_cache, value_cache = kv_cache.unbind(1)
+        flash_layout = True
+
+        is_fp8_kv_cache = self.kv_cache_dtype.startswith("fp8")
+        if is_fp8_kv_cache:
+            key_cache = key_cache.view(self.fp8_dtype)
+            value_cache = value_cache.view(self.fp8_dtype)
+
+        rocm_aiter_ops.triton_rope_and_cache(
+            query,
+            key,
+            value,
+            positions,
+            cos_sin_cache,
+            is_neox,
+            key_cache,
+            value_cache,
+            layer_slot_mapping,
+            layer._k_scale,
+            layer._v_scale,
+            flash_layout,
+            is_fp8_kv_cache,
+        )