Add vLLM v0.18.1 source tree with KV transfer abort fix

third_party/vllm/ now tracked in git for direct patch management.
Based on vLLM v0.18.1 release with one patch applied:

  vllm/v1/core/sched/scheduler.py:
    Replace fatal assert with graceful skip when KV transfer callback
    arrives for an already-aborted request during PD disaggregated serving.

Future vLLM modifications should be made directly in third_party/vllm/
and committed normally. The patches/ directory is kept as documentation
of what changed from upstream.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

third_party/vllm/csrc/rocm/ops.h

@@ -0,0 +1,30 @@
+#pragma once
+
+#include <torch/all.h>
+
+torch::Tensor LLMM1(at::Tensor& in_a, at::Tensor& in_b,
+                    const int64_t rows_per_block);
+
+torch::Tensor wvSplitK(const at::Tensor& in_a, const at::Tensor& in_b,
+                       const std::optional<at::Tensor>& in_bias,
+                       const int64_t CuCount);
+
+torch::Tensor wvSplitKrc(const at::Tensor& in_a, const at::Tensor& in_b,
+                         const std::optional<at::Tensor>& in_bias,
+                         const int64_t CuCount);
+
+void wvSplitKQ(const at::Tensor& in_a, const at::Tensor& in_b,
+               const std::optional<at::Tensor>& in_bias, at::Tensor& out_c,
+               const at::Tensor& scale_a, const at::Tensor& scale_b,
+               const int64_t CuCount);
+
+void paged_attention(
+    torch::Tensor& out, torch::Tensor& exp_sums, torch::Tensor& max_logits,
+    torch::Tensor& tmp_out, torch::Tensor& query, torch::Tensor& key_cache,
+    torch::Tensor& value_cache, int64_t num_kv_heads, double scale,
+    torch::Tensor& block_tables, torch::Tensor& seq_lens,
+    const std::optional<torch::Tensor>& query_start_loc, int64_t block_size,
+    int64_t max_seq_len, const std::optional<torch::Tensor>& alibi_slopes,
+    const std::string& kv_cache_dtype, torch::Tensor& k_scale,
+    torch::Tensor& v_scale, const std::optional<torch::Tensor>& fp8_out_scale,
+    const std::string& mfma_type);

third_party/vllm/csrc/rocm/torch_bindings.cpp

@@ -0,0 +1,63 @@
+#include "core/registration.h"
+#include "rocm/ops.h"
+
+// Note on op signatures:
+// The X_meta signatures are for the meta functions corresponding to op X.
+// They must be kept in sync with the signature for X. Generally, only
+// functions that return Tensors require a meta function.
+//
+// See the following links for detailed docs on op registration and function
+// schemas.
+// https://docs.google.com/document/d/1_W62p8WJOQQUzPsJYa7s701JXt0qf2OfLub2sbkHOaU/edit#heading=h.ptttacy8y1u9
+// https://github.com/pytorch/pytorch/blob/main/aten/src/ATen/native/README.md#annotations
+
+TORCH_LIBRARY_EXPAND(TORCH_EXTENSION_NAME, rocm_ops) {
+  // vLLM custom ops for rocm
+
+  // Custom gemm op for matrix-vector multiplication
+  rocm_ops.def(
+      "LLMM1(Tensor in_a, Tensor in_b, int rows_per_block) -> "
+      "Tensor");
+  rocm_ops.impl("LLMM1", torch::kCUDA, &LLMM1);
+
+  // Custom gemm op for skinny matrix-matrix multiplication
+  rocm_ops.def(
+      "wvSplitK(Tensor in_a, Tensor in_b, Tensor? in_bias, int CuCount) -> "
+      "Tensor");
+  rocm_ops.impl("wvSplitK", torch::kCUDA, &wvSplitK);
+
+  // Custom gemm op for skinny matrix-matrix multiplication
+  rocm_ops.def(
+      "wvSplitKrc(Tensor in_a, Tensor in_b, Tensor? in_bias, int CuCount) -> "
+      "Tensor");
+  rocm_ops.impl("wvSplitKrc", torch::kCUDA, &wvSplitKrc);
+
+  // wvSplitK for fp8
+  rocm_ops.def(
+      "wvSplitKQ(Tensor in_a, Tensor in_b, Tensor? in_bias, Tensor! out_c, "
+      "Tensor scale_a, "
+      "          Tensor scale_b, int CuCount) -> ()");
+  rocm_ops.impl("wvSplitKQ", torch::kCUDA, &wvSplitKQ);
+
+  // Custom attention op
+  // Compute the attention between an input query and the cached
+  // keys/values using PagedAttention.
+  rocm_ops.def(
+      "paged_attention(Tensor! out, Tensor exp_sums,"
+      "                Tensor max_logits, Tensor tmp_out,"
+      "                Tensor query, Tensor key_cache,"
+      "                Tensor value_cache, int num_kv_heads,"
+      "                float scale, Tensor block_tables,"
+      "                Tensor seq_lens,"
+      "                Tensor? query_start_loc,"
+      "                int block_size,"
+      "                int max_seq_len,"
+      "                Tensor? alibi_slopes,"
+      "                str kv_cache_dtype,"
+      "                Tensor k_scale, Tensor v_scale,"
+      "                Tensor? fp8_out_scale,"
+      "                str mfma_type) -> ()");
+  rocm_ops.impl("paged_attention", torch::kCUDA, &paged_attention);
+}
+
+REGISTER_EXTENSION(TORCH_EXTENSION_NAME)