[TRTLLM-6674][feat] (Breaking Change) Hopper SWA non-cyclic kernels + KV reuse + Spec Dec (#6379)

Signed-off-by: Haohang Huang <[email protected]>
Signed-off-by: symphonylyh <[email protected]>

Author: symphonylyh

cpp/kernels/fmha_v2/src/fmha/gmem_tile_qkv_packed.h

@@ -796,7 +796,6 @@ struct Gmem_tile_contiguous_kv
     template <typename Smem_tile>
     inline __device__ void load(Smem_tile& smem_tile)
     {
-        // TODO(perkzz): add remap_kv_row for sliding window attention.
         uint32_t preds[LDGS];
 #pragma unroll
         for (int ii = 0; ii < LDGS; ++ii)
@@ -1091,42 +1090,6 @@ struct Gmem_tile_paged_kv
         }
     }
 
-    ////////////////////////////////////////////////////////////////////////////////////////////////////
-    // Remap the row to the one in cyclic kv cache.
-    inline __device__ void remap_kv_row(int& row)
-    {
-        // Sliding window attention + chunked context needs special handling.
-        if constexpr (SLIDING_WINDOW_ATTENTION)
-        {
-            // For chunked context (i.e. separate q and kv layout), the kv cache might be overwritten
-            // after last chunk is processed.
-            // To deal with this issue, the new tokens' kv will be appended to the kv cache first, and
-            // overwrite the kv cache after FMHA is done.
-            // The kv input layout is like: [cyclic kv cache] + [new tokens' kv].
-            // There are two possible cases:
-            // 1. The kv cache hasn't been overwritten while processing previous chunks, so we can take
-            //    it normally, where we have full kv cache.
-            // 2. The kv cache has been overwritten while processing previous chunks. we need to mask
-            //    out the tokens in the kv cache based on the sliding window size. It needs to track the
-            //    last kv cache token's position in a circular way.
-
-            // Remap the kv row when kv cache has been overwritten in a circular way.
-            if (past_seqlen_ > sliding_window_size_)
-            {
-                // Map the kv row to the new tokens' kv.
-                if (row >= past_seqlen_)
-                {
-                    row = sliding_window_size_ + (row - past_seqlen_);
-                }
-                else
-                {
-                    // Map the kv row to the cyclic kv cache.
-                    row = row % sliding_window_size_;
-                }
-            }
-        }
-    }
-
     // Load data from memory.
     template <typename Smem_tile>
     inline __device__ void load(Smem_tile& smem_tile)
@@ -1144,13 +1107,6 @@ struct Gmem_tile_paged_kv
         for (int ii = 0; ii < LDGS; ++ii)
         {
             int row_idx = row_ + ii * (int) ROWS_PER_LDG;
-
-            // Remap row_idx if sliding window attention is used.
-            // This will be removed later as the remapping will be handled by the kvCacheManger in TRTLLM.
-#ifdef GENERATE_CUBIN
-            remap_kv_row(row_idx);
-#endif
-
             int paged_kv_block_idx = (row_idx >> paged_kv_log2_block_size_);
             char const* local_kv_ptr = reinterpret_cast<char*>(paged_kv_block_pool_ptr_
                 + params_kv_block_size_in_bytes_ * paged_kv_global_block_offsets_[paged_kv_block_idx]);

cpp/kernels/fmha_v2/src/fmha/mask.h

@@ -478,7 +478,7 @@ struct Mask<Traits, Cta_tile, 4> : public Mask<Traits, Cta_tile, 3>
     inline __device__ bool is_valid(int row, int col) const
     {
         // Is it a valid position in the sequence, i.e. are we in the lower triangle?
-        return (row >= col) && (col >= max(0, row - sliding_window_size_));
+        return (row >= col) && (col >= max(0, row + 1 - sliding_window_size_));
     }
 
     // The sliding window size.
@@ -946,7 +946,7 @@ struct Mask_hopper<Traits, Cta_tile, 4> : public Mask_hopper<Traits, Cta_tile, 3
     inline __device__ bool is_valid(int row, int col) const
     {
         // Is it a valid position in the sequence?
-        return col <= row && col >= max(0, row - sliding_window_size_);
+        return col <= row && col >= max(0, row + 1 - sliding_window_size_);
     }
 
     // The sliding window size for attention.

cpp/kernels/fmha_v2/src/fmha/warpspec/compute.h

@@ -288,7 +288,7 @@ struct Compute
             // The kv_left_mask_end is the start of the chunk.
             kv_left_mask_end = div_up(is_chunked_attention
                     ? ((tile_offset_end >> params.log2_chunked_attention_size) << params.log2_chunked_attention_size)
-                    : (tile_offset_end - params.sliding_window_size),
+                    : (tile_offset_end + 1 - params.sliding_window_size),
                 STEP_KV);
         }
 

cpp/kernels/fmha_v2/src/fmha/warpspec/dma.h

@@ -199,7 +199,7 @@ struct DMA
                 // The kv_offset_start.
                 int kv_offset_start = is_chunked_attention
                     ? ((q_step_offset >> params.log2_chunked_attention_size) << params.log2_chunked_attention_size)
-                    : max(0, q_step_offset - params.sliding_window_size);
+                    : max(0, q_step_offset + 1 - params.sliding_window_size);
                 kv_idx_start = kv_offset_start / STEP_KV;
             }
 
@@ -388,51 +388,6 @@ struct DMA
                 elect_one_, {-1, -1, -1, -1, -1, -1, -1, -1});
         }
 
-        // Calculate the start tile idx.
-        inline __device__ int remap_kv_tile_idx(
-            int kv_tile_idx, int num_kv_cache_tiles, int past_kv_length, int sliding_window_size)
-        {
-
-            // The remapped kv tile idx.
-            int remapped_kv_tile_idx = kv_tile_idx;
-            // This will be removed later as the remapping will be handled by the kvCacheManger in TRTLLM.
-#ifdef GENERATE_CUBIN
-            // Sliding window attention + chunked context needs special handling.
-            if constexpr (SLIDING_OR_CHUNKED_ATTENTION)
-            {
-                // For chunked context (i.e. separate q and kv layout), the kv cache might be
-                // overwritten after last chunk is processed.
-                // To deal with this issue, the new tokens' kv will be appended to the kv cache first,
-                // and overwrite the kv cache after FMHA is done.
-                // The kv input layout is like: [cyclic kv cache] + [new tokens' kv].
-                // There are two possible cases:
-                // 1. The kv cache hasn't been overwritten while processing previous chunks, so we can
-                //    take it normally, where we have full kv cache.
-                // 2. The kv cache has been overwritten while processing previous chunks. we need to
-                //    mask out the tokens in the kv cache based on the sliding window size. It needs
-                //    to track the last kv cache token's position in a circular way.
-
-                // Remap the kv tile index when kv cache has been overwritten in a circular way.
-                if (past_kv_length > sliding_window_size)
-                {
-                    // Map the kv tile index to the new tokens' kv.
-                    if (kv_tile_idx * STEP_KV >= past_kv_length)
-                    {
-                        remapped_kv_tile_idx
-                            = num_kv_cache_tiles + int((kv_tile_idx * STEP_KV - past_kv_length) / STEP_KV);
-                    }
-                    else
-                    {
-                        // Map the kv tile index to the cyclic kv cache.
-                        remapped_kv_tile_idx = kv_tile_idx % num_kv_cache_tiles;
-                    }
-                }
-            }
-#endif
-            // Return the remapped kv tile idx.
-            return remapped_kv_tile_idx;
-        }
-
         // Support contiguous Q + contiguous/paged KV separate cache.
         inline __device__ void run_separate_q_and_kv(
             bert::Fused_multihead_attention_params_v2 const& params, Shared* shared)
@@ -560,24 +515,20 @@ struct DMA
                     // Iterate over the kv tiles for this q step.
                     for (int kv_step_idx = kv_idx_start; kv_step_idx < kv_idx_end; kv_step_idx++)
                     {
-                        // Remap the kv tile idx if sliding window attention is enabled.
-                        // Sliding_window_size should be multiple of STEP_KV.
-                        int remapped_kv_step_idx = remap_kv_tile_idx(kv_step_idx, params.sliding_window_size / STEP_KV,
-                            past_kv_length, params.sliding_window_size);
                         // The barrier id.
                         int bar_id;
                         // Load paged kv input.
                         if constexpr (PAGED_KV_INPUT)
                         {
-                            bar_id = load_paged_kv(bidh_kv, remapped_kv_step_idx * STEP_KV, num_valid_kv_blocks,
+                            bar_id = load_paged_kv(bidh_kv, kv_step_idx * STEP_KV, num_valid_kv_blocks,
                                 params.paged_kv_cache.mTokensPerBlockLog2, params.blocks_per_tma_load,
                                 params.blocks_per_tma_load_log2, params.paged_kv_cache.mMaxBlocksPerSeq,
                                 paged_block_offsets, desc_k, desc_v, shared, cbw_k, cbw_v, cbw_v_scratch);
                         }
                         else
                         {
-                            bar_id = load_kv(bidh_kv, remapped_kv_step_idx * STEP_KV, desc_k, desc_v, shared, cbw_k,
-                                cbw_v, cbw_v_scratch);
+                            bar_id = load_kv(
+                                bidh_kv, kv_step_idx * STEP_KV, desc_k, desc_v, shared, cbw_k, cbw_v, cbw_v_scratch);
                         }
 
                         // Opportunistically hide headinfo in the shadow of UTMALDGs of the QKV tensor

cpp/kernels/fmha_v2/src/fmha/warpspec/epilogue.h

@@ -134,7 +134,7 @@ struct Softmax_base
         else
         {
             // The sliding window start is the max of 0 and row - sliding_window_size.
-            return max(0, row - sliding_window_size_);
+            return max(0, row + 1 - sliding_window_size_);
         }
     }
 

cpp/kernels/fmha_v2/src/fused_multihead_attention.cpp

@@ -1578,7 +1578,7 @@ int main(int argc, char** argv)
                     }
                     else
                     {
-                        valid = valid && (si >= std::max(int(so - sliding_window_size), 0));
+                        valid = valid && (si >= std::max(int(so + 1 - sliding_window_size), 0));
                     }
                 }
                 if (is_mtp)

cpp/kernels/fmha_v2/src/fused_multihead_flash_attention_kernel_noloop.h

@@ -175,10 +175,10 @@ inline __device__ void device_flash_attention_nl(Params const& params)
 
     int const kv_loop_end = ((valid_seqlen + Cta_tile_p::N - 1) / Cta_tile_p::N) * Cta_tile_p::N;
     int const kv_loop_start = mask_sliding_window
-        ? (max(0, q_sequence_start - params.sliding_window_size) / Cta_tile_p::N) * Cta_tile_p::N
+        ? (max(0, q_sequence_start + 1 - params.sliding_window_size) / Cta_tile_p::N) * Cta_tile_p::N
         : 0;
     int const sliding_window_mask_end = mask_sliding_window
-        ? (max(0, q_sequence_start + Cta_tile_p::M - 1 - params.sliding_window_size) / Cta_tile_p::N) * Cta_tile_p::N
+        ? (max(0, q_sequence_start + Cta_tile_p::M - params.sliding_window_size) / Cta_tile_p::N) * Cta_tile_p::N
         : 0;
 
     static_assert(Cta_tile_p::M >= Cta_tile_p::N, "");

cpp/kernels/fmha_v2/src/fused_multihead_flash_attention_kernel_noloop_tiled.h

@@ -176,10 +176,10 @@ inline __device__ void device_flash_attention_nl_tiled(Params const& params)
 
     int const kv_loop_end = ((valid_seqlen + Cta_tile_p::N - 1) / Cta_tile_p::N) * Cta_tile_p::N;
     int const kv_loop_start = mask_sliding_window
-        ? (max(0, q_sequence_start - params.sliding_window_size) / Cta_tile_p::N) * Cta_tile_p::N
+        ? (max(0, q_sequence_start + 1 - params.sliding_window_size) / Cta_tile_p::N) * Cta_tile_p::N
         : 0;
     int const sliding_window_mask_end = mask_sliding_window
-        ? (max(0, q_sequence_start + Cta_tile_p::M - 1 - params.sliding_window_size) / Cta_tile_p::N) * Cta_tile_p::N
+        ? (max(0, q_sequence_start + Cta_tile_p::M - params.sliding_window_size) / Cta_tile_p::N) * Cta_tile_p::N
         : 0;
 
     // Move K and V tiles.

cpp/kernels/xqa/defines.h

@@ -162,6 +162,10 @@ static_assert(CACHE_ELEM_ENUM != 0);
 #define OPTIMIZE_FOR_LATENCY 1
 #endif
 
+#ifndef IS_SPEC_DEC_TREE
+#define IS_SPEC_DEC_TREE 1 // by default SPEC_DEC expect tree-based draft token structure
+#endif
+
 #define DBG_BATCH_SIZE 2
 #define DBG_SEQ_LEN 256 * 4 + 3
 #define DBG_NB_CTAS_PER_SEQ 8

cpp/kernels/xqa/mha.cu

@@ -1592,7 +1592,6 @@ CUBIN_EXPORT __global__
 #endif
 
     uint32_t const cacheSeqLen = getCacheSeqLen<usePagedKVCache>(cacheList, idxReq);
-    static_assert(!(allowSlidingWindow && useSpecDec), "Sliding window is not yet supported in spec-dec mode");
 #if SLIDING_WINDOW
     bool const rtIsReallySliding = (cacheSeqLen > slidingWinSize);
     uint32_t const nbTotalSkipTokens = rtIsReallySliding ? cacheSeqLen - slidingWinSize : 0;