IB/mlx5: Fix binary compatibility with libmlx5

Commit c1be5232d21d ("Fix micro UAR allocator") broke binary compatibility
between libmlx5 and mlx5_ib since it defines a different value to the number
of micro UARs per page, leading to wrong calculation in libmlx5. This patch
defines struct mlx5_ib_alloc_ucontext_req_v2 as an extension to struct
mlx5_ib_alloc_ucontext_req.  The extended size is determined in mlx5_ib_alloc_ucontext()
and in case of old library we use uuarn 0 which works fine -- this is
acheived due to create_user_qp() falling back from high to medium then to
low class where low class will return 0.  For new libraries we use the
more sophisticated allocation algorithm.

Signed-off-by: Eli Cohen <eli@mellanox.com>
Reviewed-by: Yann Droneaud <ydroneaud@opteya.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

4 files changed, 33 insertions, 4 deletions

diff --git a/drivers/infiniband/hw/mlx5/main.c b/drivers/infiniband/hw/mlx5/main.c
index 9660d093f8cf..f4ef4a24d410 100644
--- a/drivers/infiniband/hw/mlx5/main.c
+++ b/drivers/infiniband/hw/mlx5/main.c
@@ -536,24 +536,38 @@ static struct ib_ucontext *mlx5_ib_alloc_ucontext(struct ib_device *ibdev,
                                                   struct ib_udata *udata)
 {
         struct mlx5_ib_dev *dev = to_mdev(ibdev);
-        struct mlx5_ib_alloc_ucontext_req req;
+        struct mlx5_ib_alloc_ucontext_req_v2 req;
         struct mlx5_ib_alloc_ucontext_resp resp;
         struct mlx5_ib_ucontext *context;
         struct mlx5_uuar_info *uuari;
         struct mlx5_uar *uars;
         int gross_uuars;
         int num_uars;
+        int ver;
         int uuarn;
         int err;
         int i;
+        int reqlen;
 
         if (!dev->ib_active)
                 return ERR_PTR(-EAGAIN);
 
-        err = ib_copy_from_udata(&req, udata, sizeof(req));
+        memset(&req, 0, sizeof(req));
+        reqlen = udata->inlen - sizeof(struct ib_uverbs_cmd_hdr);
+        if (reqlen == sizeof(struct mlx5_ib_alloc_ucontext_req))
+                ver = 0;
+        else if (reqlen == sizeof(struct mlx5_ib_alloc_ucontext_req_v2))
+                ver = 2;
+        else
+                return ERR_PTR(-EINVAL);
+
+        err = ib_copy_from_udata(&req, udata, reqlen);
         if (err)
                 return ERR_PTR(err);
 
+        if (req.flags || req.reserved)
+                return ERR_PTR(-EINVAL);
+
         if (req.total_num_uuars > MLX5_MAX_UUARS)
                 return ERR_PTR(-ENOMEM);
 
@@ -626,6 +640,7 @@ static struct ib_ucontext *mlx5_ib_alloc_ucontext(struct ib_device *ibdev,
         if (err)
                 goto out_uars;
 
+        uuari->ver = ver;
         uuari->num_low_latency_uuars = req.num_low_latency_uuars;
         uuari->uars = uars;
         uuari->num_uars = num_uars;
diff --git a/drivers/infiniband/hw/mlx5/qp.c b/drivers/infiniband/hw/mlx5/qp.c
index 492dc330e907..091576a777e9 100644
--- a/drivers/infiniband/hw/mlx5/qp.c
+++ b/drivers/infiniband/hw/mlx5/qp.c
@@ -430,11 +430,17 @@ static int alloc_uuar(struct mlx5_uuar_info *uuari,
                 break;
 
         case MLX5_IB_LATENCY_CLASS_MEDIUM:
-                uuarn = alloc_med_class_uuar(uuari);
+                if (uuari->ver < 2)
+                        uuarn = -ENOMEM;
+                else
+                        uuarn = alloc_med_class_uuar(uuari);
                 break;
 
         case MLX5_IB_LATENCY_CLASS_HIGH:
-                uuarn = alloc_high_class_uuar(uuari);
+                if (uuari->ver < 2)
+                        uuarn = -ENOMEM;
+                else
+                        uuarn = alloc_high_class_uuar(uuari);
                 break;
 
         case MLX5_IB_LATENCY_CLASS_FAST_PATH:
diff --git a/drivers/infiniband/hw/mlx5/user.h b/drivers/infiniband/hw/mlx5/user.h
index 32a2a5dfc523..0f4f8e42a17f 100644
--- a/drivers/infiniband/hw/mlx5/user.h
+++ b/drivers/infiniband/hw/mlx5/user.h
@@ -62,6 +62,13 @@ struct mlx5_ib_alloc_ucontext_req {
         __u32   num_low_latency_uuars;
 };
 
+struct mlx5_ib_alloc_ucontext_req_v2 {
+        __u32   total_num_uuars;
+        __u32   num_low_latency_uuars;
+        __u32   flags;
+        __u32   reserved;
+};
+
 struct mlx5_ib_alloc_ucontext_resp {
         __u32   qp_tab_size;
         __u32   bf_reg_size;
diff --git a/include/linux/mlx5/driver.h b/include/linux/mlx5/driver.h
index 554548cd3dd4..32cb18c399c2 100644
--- a/include/linux/mlx5/driver.h
+++ b/include/linux/mlx5/driver.h
@@ -227,6 +227,7 @@ struct mlx5_uuar_info {
          * protect uuar allocation data structs
          */
         struct mutex            lock;
+        u32                     ver;
 };
 
 struct mlx5_bf {