1 files changed, 5 insertions, 3 deletions
diff --git a/candle-flash-attn/kernels/block_info.h b/candle-flash-attn/kernels/block_info.h
index 3a23a1e1..cf60d653 100644
--- a/candle-flash-attn/kernels/block_info.h
+++ b/candle-flash-attn/kernels/block_info.h
@@ -18,8 +18,9 @@ struct BlockInfo {
         , actual_seqlen_q(!Varlen || params.cu_seqlens_q == nullptr ? params.seqlen_q : params.cu_seqlens_q[bidb + 1] - sum_s_q)
         // If is_seqlens_k_cumulative, then seqlen_k is cu_seqlens_k[bidb + 1] - cu_seqlens_k[bidb].
         // Otherwise it's cu_seqlens_k[bidb], i.e., we use cu_seqlens_k to store the sequence lengths of K.
-        , seqlen_k_cache(!Varlen || params.cu_seqlens_k == nullptr ? params.seqlen_k : (params.is_seqlens_k_cumulative ? params.cu_seqlens_k[bidb + 1] - sum_s_k : params.cu_seqlens_k[bidb]))
-        , actual_seqlen_k(params.seqused_k ? params.seqused_k[bidb] : seqlen_k_cache + (params.knew_ptr == nullptr ? 0 : params.seqlen_knew))
+        , leftpad_k(params.leftpad_k == nullptr ? 0 : params.leftpad_k[bidb])
+        , seqlen_k_cache((!Varlen || params.cu_seqlens_k == nullptr ? params.seqlen_k : (params.is_seqlens_k_cumulative ? params.cu_seqlens_k[bidb + 1] - sum_s_k : params.cu_seqlens_k[bidb])) - leftpad_k)
+        , actual_seqlen_k(params.seqused_k ? params.seqused_k[bidb] - leftpad_k : seqlen_k_cache + (params.knew_ptr == nullptr ? 0 : params.seqlen_knew))
         {
         }
 
@@ -30,13 +31,14 @@ struct BlockInfo {
 
     template <typename index_t>
     __forceinline__ __device__ index_t k_offset(const index_t batch_stride, const index_t row_stride, const int bidb) const {
-        return sum_s_k == -1 ? bidb * batch_stride : uint32_t(sum_s_k) * row_stride;
+        return sum_s_k == -1 ? bidb * batch_stride + leftpad_k * row_stride : uint32_t(sum_s_k + leftpad_k) * row_stride;
     }
 
     const int sum_s_q;
     const int sum_s_k;
     const int actual_seqlen_q;
     // We have to have seqlen_k_cache declared before actual_seqlen_k, otherwise actual_seqlen_k is set to 0.
+    const int leftpad_k;
     const int seqlen_k_cache;
     const int actual_seqlen_k;
 };