IB/mlx5: Ensure proper synchronization accessing memory

Call mlx5_ib_populate_pas() before mapping the DMA buffer to ensure
the hardware reads the values written by the CPU.

Found by: Haggai Eran <haggaie@mellanox.com>
Signed-off-by: Eli Cohen <eli@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

1 files changed, 4 insertions, 3 deletions

diff --git a/drivers/infiniband/hw/mlx5/mr.c b/drivers/infiniband/hw/mlx5/mr.c
index 154241290f5c..3453580b1eb2 100644
--- a/drivers/infiniband/hw/mlx5/mr.c
+++ b/drivers/infiniband/hw/mlx5/mr.c
@@ -680,6 +680,10 @@ static struct mlx5_ib_mr *reg_umr(struct ib_pd *pd, struct ib_umem *umem,
                 err = -ENOMEM;
                 goto error;
         }
+
+        mlx5_ib_populate_pas(dev, umem, page_shift,
+                             mr_align(mr->pas, MLX5_UMR_ALIGN), 1);
+
         mr->dma = dma_map_single(ddev, mr_align(mr->pas, MLX5_UMR_ALIGN), size,
                                  DMA_TO_DEVICE);
         if (dma_mapping_error(ddev, mr->dma)) {
@@ -688,9 +692,6 @@ static struct mlx5_ib_mr *reg_umr(struct ib_pd *pd, struct ib_umem *umem,
                 goto error;
         }
 
-        mlx5_ib_populate_pas(dev, umem, page_shift,
-                             mr_align(mr->pas, MLX5_UMR_ALIGN), 1);
-
         memset(&wr, 0, sizeof(wr));
         wr.wr_id = (u64)(unsigned long)mr;
         prep_umr_reg_wqe(pd, &wr, &sg, mr->dma, npages, mr->mmr.key, page_shift, virt_addr, len, access_flags);