IB/mthca: Give reserved MTTs a separate cache line

MTTs are allocated in non-cache-coherent memory, so we must give
reserved MTTs their own cache line, to prevent both device and
CPU from writing into the same cache line at the same time.

Signed-off-by: Michael S. Tsirkin <mst@mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/infiniband/hw/mthca/mthca_main.c b/drivers/infiniband/hw/mthca/mthca_main.c
index 44bc6cc734ab..9a9dd32885a0 100644
--- a/drivers/infiniband/hw/mthca/mthca_main.c
+++ b/drivers/infiniband/hw/mthca/mthca_main.c
@@ -464,6 +464,10 @@ static int mthca_init_icm(struct mthca_dev *mdev,
                 goto err_unmap_aux;
         }
 
+        /* CPU writes to non-reserved MTTs, while HCA might DMA to reserved mtts */
+        mdev->limits.reserved_mtts = ALIGN(mdev->limits.reserved_mtts * MTHCA_MTT_SEG_SIZE,
+                                           dma_get_cache_alignment()) / MTHCA_MTT_SEG_SIZE;
+
         mdev->mr_table.mtt_table = mthca_alloc_icm_table(mdev, init_hca->mtt_base,
                                                          MTHCA_MTT_SEG_SIZE,
                                                          mdev->limits.num_mtt_segs,