[V1] Move more control of kv cache initialization from model_executor to EngineCore (#11960)

Signed-off-by: Chen Zhang <zhangch99@outlook.com>
Co-authored-by: Cody Yu <hao.yu.cody@gmail.com>

tests/v1/test_utils.py

@@ -0,0 +1,62 @@
+from typing import List
+
+import torch
+
+from vllm.v1.utils import bind_kv_cache
+
+
+def test_bind_kv_cache():
+    from vllm.attention import Attention
+
+    ctx = {
+        'layers.0.self_attn': Attention(32, 128, 0.1),
+        'layers.1.self_attn': Attention(32, 128, 0.1),
+        'layers.2.self_attn': Attention(32, 128, 0.1),
+        'layers.3.self_attn': Attention(32, 128, 0.1),
+    }
+    kv_cache = {
+        'layers.0.self_attn': torch.zeros((1, )),
+        'layers.1.self_attn': torch.zeros((1, )),
+        'layers.2.self_attn': torch.zeros((1, )),
+        'layers.3.self_attn': torch.zeros((1, )),
+    }
+    runner_kv_caches: List[torch.Tensor] = []
+    bind_kv_cache(kv_cache, ctx, runner_kv_caches)
+    assert ctx['layers.0.self_attn'].kv_cache[0] is kv_cache[
+        'layers.0.self_attn']
+    assert ctx['layers.1.self_attn'].kv_cache[0] is kv_cache[
+        'layers.1.self_attn']
+    assert ctx['layers.2.self_attn'].kv_cache[0] is kv_cache[
+        'layers.2.self_attn']
+    assert ctx['layers.3.self_attn'].kv_cache[0] is kv_cache[
+        'layers.3.self_attn']
+
+    assert runner_kv_caches[0] is kv_cache['layers.0.self_attn']
+    assert runner_kv_caches[1] is kv_cache['layers.1.self_attn']
+    assert runner_kv_caches[2] is kv_cache['layers.2.self_attn']
+    assert runner_kv_caches[3] is kv_cache['layers.3.self_attn']
+
+
+def test_bind_kv_cache_non_attention():
+    from vllm.attention import Attention
+
+    # example from Jamba PP=2
+    ctx = {
+        'model.layers.20.attn': Attention(32, 128, 0.1),
+        'model.layers.28.attn': Attention(32, 128, 0.1),
+    }
+    kv_cache = {
+        'model.layers.20.attn': torch.zeros((1, )),
+        'model.layers.28.attn': torch.zeros((1, )),
+    }
+
+    runner_kv_caches: List[torch.Tensor] = []
+    bind_kv_cache(kv_cache, ctx, runner_kv_caches)
+
+    assert ctx['model.layers.20.attn'].kv_cache[0] is kv_cache[
+        'model.layers.20.attn']
+    assert ctx['model.layers.28.attn'].kv_cache[0] is kv_cache[
+        'model.layers.28.attn']
+
+    assert runner_kv_caches[0] is kv_cache['model.layers.20.attn']
+    assert runner_kv_caches[1] is kv_cache['model.layers.28.attn']