mlx4_core: Use MOD_STAT_CFG command to get minimal page size

There was a bug in some versions of the mlx4 driver in
mlx4_alloc_fmr(), which hardcoded the minimum acceptable page_shift to
be 12.  However, new ConnectX firmware can support a minimum
page_shift of 9 (log_pg_sz of 9 returned by QUERY_DEV_LIM) -- so with
old drivers, ib_fmr_alloc() would fail for ULPs using the device
minimum when creating FMRs.

To preserve firmware compatibility with released mlx4 drivers, the
firmware will continue to return 12 as before for log_page_sz in
QUERY_DEV_CAP for these drivers.  However, to enable new drivers to
take advantage of the available smaller page size, the mlx4 driver now
first sets the log_pg_sz to the device minimum by setting a
log_page_sz value to 0 via the MOD_STAT_CFG command and then reading
the real minimum via QUERY_DEV_CAP.

Signed-off-by: Jack Morgenstein <jackm@mellanox.co.il>
Signed-off-by: Vladimir Sokolovsky <vlad@mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/net/mlx4/fw.c

@@ -101,6 +101,34 @@ static void dump_dev_cap_flags(struct mlx4_dev *dev, u32 flags)
 			mlx4_dbg(dev, "    %s\n", fname[i]);
 }
 
+int mlx4_MOD_STAT_CFG(struct mlx4_dev *dev, struct mlx4_mod_stat_cfg *cfg)
+{
+	struct mlx4_cmd_mailbox *mailbox;
+	u32 *inbox;
+	int err = 0;
+
+#define MOD_STAT_CFG_IN_SIZE		0x100
+
+#define MOD_STAT_CFG_PG_SZ_M_OFFSET	0x002
+#define MOD_STAT_CFG_PG_SZ_OFFSET	0x003
+
+	mailbox = mlx4_alloc_cmd_mailbox(dev);
+	if (IS_ERR(mailbox))
+		return PTR_ERR(mailbox);
+	inbox = mailbox->buf;
+
+	memset(inbox, 0, MOD_STAT_CFG_IN_SIZE);
+
+	MLX4_PUT(inbox, cfg->log_pg_sz, MOD_STAT_CFG_PG_SZ_OFFSET);
+	MLX4_PUT(inbox, cfg->log_pg_sz_m, MOD_STAT_CFG_PG_SZ_M_OFFSET);
+
+	err = mlx4_cmd(dev, mailbox->dma, 0, 0, MLX4_CMD_MOD_STAT_CFG,
+			MLX4_CMD_TIME_CLASS_A);
+
+	mlx4_free_cmd_mailbox(dev, mailbox);
+	return err;
+}
+
 int mlx4_QUERY_DEV_CAP(struct mlx4_dev *dev, struct mlx4_dev_cap *dev_cap)
 {
 	struct mlx4_cmd_mailbox *mailbox;

drivers/net/mlx4/fw.h

@@ -38,6 +38,11 @@
 #include "mlx4.h"
 #include "icm.h"
 
+struct mlx4_mod_stat_cfg {
+	u8 log_pg_sz;
+	u8 log_pg_sz_m;
+};
+
 struct mlx4_dev_cap {
 	int max_srq_sz;
 	int max_qp_sz;
@@ -162,5 +167,6 @@ int mlx4_SET_ICM_SIZE(struct mlx4_dev *dev, u64 icm_size, u64 *aux_pages);
 int mlx4_MAP_ICM_AUX(struct mlx4_dev *dev, struct mlx4_icm *icm);
 int mlx4_UNMAP_ICM_AUX(struct mlx4_dev *dev);
 int mlx4_NOP(struct mlx4_dev *dev);
+int mlx4_MOD_STAT_CFG(struct mlx4_dev *dev, struct mlx4_mod_stat_cfg *cfg);
 
 #endif /* MLX4_FW_H */

drivers/net/mlx4/main.c

@@ -485,6 +485,7 @@ static int mlx4_init_hca(struct mlx4_dev *dev)
 	struct mlx4_priv	  *priv = mlx4_priv(dev);
 	struct mlx4_adapter	   adapter;
 	struct mlx4_dev_cap	   dev_cap;
+	struct mlx4_mod_stat_cfg   mlx4_cfg;
 	struct mlx4_profile	   profile;
 	struct mlx4_init_hca_param init_hca;
 	u64 icm_size;
@@ -502,6 +503,12 @@ static int mlx4_init_hca(struct mlx4_dev *dev)
 		return err;
 	}
 
+	mlx4_cfg.log_pg_sz_m = 1;
+	mlx4_cfg.log_pg_sz = 0;
+	err = mlx4_MOD_STAT_CFG(dev, &mlx4_cfg);
+	if (err)
+		mlx4_warn(dev, "Failed to override log_pg_sz parameter\n");
+
 	err = mlx4_dev_cap(dev, &dev_cap);
 	if (err) {
 		mlx4_err(dev, "QUERY_DEV_CAP command failed, aborting.\n");