fix mask with flash attn

Author: Green-Sky

ggml_extend.hpp

@@ -944,6 +944,18 @@ __STATIC_INLINE__ struct ggml_tensor* ggml_nn_attention_ext(struct ggml_context*
         v = ggml_reshape_3d(ctx, v, d_head, L_k, n_head * N);  // [N * n_head, L_k, d_head]
         v = ggml_cast(ctx, v, GGML_TYPE_F16);
 
+        if (mask != nullptr) {
+            mask = ggml_transpose(ctx, mask);
+
+            if (mask->ne[1] < GGML_PAD(q->ne[1], GGML_KQ_MASK_PAD)) {
+                LOG_DEBUG("mask dims %ld, %ld, %ld, %ld\n", mask->ne[0], mask->ne[1], mask->ne[2], mask->ne[3]);
+                LOG_DEBUG("needs padding, padding from %ld to %ld\n", mask->ne[1], GGML_PAD(q->ne[1], GGML_KQ_MASK_PAD));
+                mask = ggml_pad(ctx, mask, 0, GGML_PAD(q->ne[1], GGML_KQ_MASK_PAD) - mask->ne[1], 0, 0);
+            }
+
+            mask = ggml_cast(ctx, mask, GGML_TYPE_F16);
+        }
+
         kqv = ggml_flash_attn_ext(ctx, q, k, v, mask, scale, 0, 0);
         ggml_flash_attn_ext_set_prec(kqv, GGML_PREC_F32);