IB/mlx4: Don't overwrite fast registration page list when posting work request

The low-level mlx4 driver modified the page-list addresses for fast
register work requests post send to big-endian, and set a "present"
bit.  This caused problems later when the consumer attempted to unmap
the pages using the page-list (using the list addresses which were
assumed to be still in CPU-endian order).  Fix the mlx4 driver to
allocate two buffers and use a private buffer for the hardware-format
bus addresses.

This patch fixes <https://bugs.openfabrics.org/show_bug.cgi?id=1571>,
an NFS/RDMA server crash.  The cause of the crash was found by Vu Pham
of Mellanox.  The fix is along the lines suggested by Steve Wise in
comment #21 in bug 1571.
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/hw/mlx4/mlx4_ib.h

@@ -86,6 +86,7 @@ struct mlx4_ib_mr {
 
 struct mlx4_ib_fast_reg_page_list {
 	struct ib_fast_reg_page_list	ibfrpl;
+	__be64			       *mapped_page_list;
 	dma_addr_t			map;
 };
 

drivers/infiniband/hw/mlx4/mr.c

@@ -231,7 +231,11 @@ struct ib_fast_reg_page_list *mlx4_ib_alloc_fast_reg_page_list(struct ib_device
 	if (!mfrpl)
 		return ERR_PTR(-ENOMEM);
 
-	mfrpl->ibfrpl.page_list = dma_alloc_coherent(&dev->dev->pdev->dev,
+	mfrpl->ibfrpl.page_list = kmalloc(size, GFP_KERNEL);
+	if (!mfrpl->ibfrpl.page_list)
+		goto err_free;
+
+	mfrpl->mapped_page_list = dma_alloc_coherent(&dev->dev->pdev->dev,
 						     size, &mfrpl->map,
 						     GFP_KERNEL);
 	if (!mfrpl->ibfrpl.page_list)
@@ -242,6 +246,7 @@ struct ib_fast_reg_page_list *mlx4_ib_alloc_fast_reg_page_list(struct ib_device
 	return &mfrpl->ibfrpl;
 
 err_free:
+	kfree(mfrpl->ibfrpl.page_list);
 	kfree(mfrpl);
 	return ERR_PTR(-ENOMEM);
 }
@@ -252,8 +257,9 @@ void mlx4_ib_free_fast_reg_page_list(struct ib_fast_reg_page_list *page_list)
 	struct mlx4_ib_fast_reg_page_list *mfrpl = to_mfrpl(page_list);
 	int size = page_list->max_page_list_len * sizeof (u64);
 
-	dma_free_coherent(&dev->dev->pdev->dev, size, page_list->page_list,
+	dma_free_coherent(&dev->dev->pdev->dev, size, mfrpl->mapped_page_list,
 			  mfrpl->map);
+	kfree(mfrpl->ibfrpl.page_list);
 	kfree(mfrpl);
 }
 

drivers/infiniband/hw/mlx4/qp.c

@@ -1365,7 +1365,7 @@ static void set_fmr_seg(struct mlx4_wqe_fmr_seg *fseg, struct ib_send_wr *wr)
 	int i;
 
 	for (i = 0; i < wr->wr.fast_reg.page_list_len; ++i)
-		wr->wr.fast_reg.page_list->page_list[i] =
+		mfrpl->mapped_page_list[i] =
 			cpu_to_be64(wr->wr.fast_reg.page_list->page_list[i] |
 				    MLX4_MTT_FLAG_PRESENT);