Ck tile/paged attention workaround (#1894)

* Correction in GetRangeAlongX()

* Work-around to solve the failures in test_paged_attention_ck in xformers

include/ck_tile/ops/fmha/block/block_masking.hpp

@@ -310,7 +310,7 @@ struct SimplifiedGenericAttentionMask
 
         const index_t x_per_split = ck_tile::max(1, integer_divide_ceil(x_total, num_splits));
         const index_t split_start = x_per_split * i_split;
-        const index_t split_end   = split_start + x_per_split;
+        const index_t split_end   = ck_tile::min(x_total, split_start + x_per_split);
 
         return ck_tile::make_tuple(ck_tile::max(origin_start, split_start),
                                    ck_tile::min(origin_end, split_end));

include/ck_tile/ops/fmha/kernel/fmha_fwd_splitkv_kernel.hpp

@@ -742,7 +742,7 @@ struct FmhaFwdSplitKVKernel
                 return pad_tensor_view(
                     v_dram_transposed,
                     make_tuple(number<FmhaPipeline::kN1>{}, number<FmhaPipeline::kK1>{}),
-                    sequence<kPadHeadDimV, false>{});
+                    sequence<kPadHeadDimV, kPadSeqLenK>{});
             }
             else
             {