mlx4: Enforce device max FMR maps in FMR alloc

ConnectX devices have a limit on the number of mappings that can be
done on an FMR before having to call sync_tpt.  The current
mlx4_ib driver reports the limit correctly in max_map_per_fmr in
.query_device(), but mlx4_core doesn't check it when actually
allocating FMRs.

Add a max_fmr_maps field to struct mlx4_caps and enforce this maximum
value on FMR allocations.

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

drivers/infiniband/hw/mlx4/main.c

@@ -163,7 +163,7 @@ static int mlx4_ib_query_device(struct ib_device *ibdev,
 	props->max_mcast_qp_attach = dev->dev->caps.num_qp_per_mgm;
 	props->max_total_mcast_qp_attach = props->max_mcast_qp_attach *
 					   props->max_mcast_grp;
-	props->max_map_per_fmr = (1 << (32 - ilog2(dev->dev->caps.num_mpts))) - 1;
+	props->max_map_per_fmr = dev->dev->caps.max_fmr_maps;
 
 out:
 	kfree(in_mad);

drivers/net/ethernet/mellanox/mlx4/main.c

@@ -1131,6 +1131,8 @@ static int mlx4_init_hca(struct mlx4_dev *dev)
 			goto err_stop_fw;
 		}
 
+		dev->caps.max_fmr_maps = (1 << (32 - ilog2(dev->caps.num_mpts))) - 1;
+
 		init_hca.log_uar_sz = ilog2(dev->caps.num_uars);
 		init_hca.uar_page_sz = PAGE_SHIFT - 12;
 

drivers/net/ethernet/mellanox/mlx4/mr.c

@@ -816,6 +816,9 @@ int mlx4_fmr_alloc(struct mlx4_dev *dev, u32 pd, u32 access, int max_pages,
 	u64 mtt_offset;
 	int err = -ENOMEM;
 
+	if (max_maps > dev->caps.max_fmr_maps)
+		return -EINVAL;
+
 	if (page_shift < (ffs(dev->caps.page_size_cap) - 1) || page_shift >= 32)
 		return -EINVAL;
 

include/linux/mlx4/device.h

@@ -273,6 +273,7 @@ struct mlx4_caps {
 	int			num_comp_vectors;
 	int			comp_pool;
 	int			num_mpts;
+	int			max_fmr_maps;
 	int			num_mtts;
 	int			fmr_reserved_mtts;
 	int			reserved_mtts;