IB/mlx5: Add DEVX query EQN support

Return the matching device EQN for a given user vector number via the
DEVX interface.

Note:
EQs are owned by the kernel and shared by all user processes.
Basically, a user CQ can point to any EQ.
The kernel doesn't enforce any such limitation today either.

Signed-off-by: Yishai Hadas <yishaih@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/hw/mlx5/devx.c

@@ -389,6 +389,31 @@ static bool devx_is_general_cmd(void *in)
 	}
 }
 
+static int UVERBS_HANDLER(MLX5_IB_METHOD_DEVX_QUERY_EQN)(struct ib_device *ib_dev,
+				  struct ib_uverbs_file *file,
+				  struct uverbs_attr_bundle *attrs)
+{
+	struct mlx5_ib_dev *dev = to_mdev(ib_dev);
+	int user_vector;
+	int dev_eqn;
+	unsigned int irqn;
+	int err;
+
+	if (uverbs_copy_from(&user_vector, attrs,
+			     MLX5_IB_ATTR_DEVX_QUERY_EQN_USER_VEC))
+		return -EFAULT;
+
+	err = mlx5_vector2eqn(dev->mdev, user_vector, &dev_eqn, &irqn);
+	if (err < 0)
+		return err;
+
+	if (uverbs_copy_to(attrs, MLX5_IB_ATTR_DEVX_QUERY_EQN_DEV_EQN,
+			   &dev_eqn, sizeof(dev_eqn)))
+		return -EFAULT;
+
+	return 0;
+}
+
 /*
  *Security note:
  * The hardware protection mechanism works like this: Each device object that
@@ -979,6 +1004,12 @@ static DECLARE_UVERBS_NAMED_METHOD(MLX5_IB_METHOD_DEVX_UMEM_DEREG,
 			 UVERBS_ACCESS_DESTROY,
 			 UA_FLAGS(UVERBS_ATTR_SPEC_F_MANDATORY)));
 
+static DECLARE_UVERBS_NAMED_METHOD(MLX5_IB_METHOD_DEVX_QUERY_EQN,
+	&UVERBS_ATTR_PTR_IN(MLX5_IB_ATTR_DEVX_QUERY_EQN_USER_VEC, UVERBS_ATTR_TYPE(u32),
+			    UA_FLAGS(UVERBS_ATTR_SPEC_F_MANDATORY)),
+	&UVERBS_ATTR_PTR_OUT(MLX5_IB_ATTR_DEVX_QUERY_EQN_DEV_EQN, UVERBS_ATTR_TYPE(u32),
+			     UA_FLAGS(UVERBS_ATTR_SPEC_F_MANDATORY)));
+
 static DECLARE_UVERBS_NAMED_METHOD(MLX5_IB_METHOD_DEVX_QUERY_UAR,
 	&UVERBS_ATTR_PTR_IN(MLX5_IB_ATTR_DEVX_QUERY_UAR_USER_IDX, UVERBS_ATTR_TYPE(u32),
 			    UA_FLAGS(UVERBS_ATTR_SPEC_F_MANDATORY)),
@@ -1050,7 +1081,8 @@ static DECLARE_UVERBS_NAMED_METHOD(MLX5_IB_METHOD_DEVX_OBJ_QUERY,
 
 static DECLARE_UVERBS_GLOBAL_METHODS(MLX5_IB_OBJECT_DEVX,
 	&UVERBS_METHOD(MLX5_IB_METHOD_DEVX_OTHER),
-	&UVERBS_METHOD(MLX5_IB_METHOD_DEVX_QUERY_UAR));
+	&UVERBS_METHOD(MLX5_IB_METHOD_DEVX_QUERY_UAR),
+	&UVERBS_METHOD(MLX5_IB_METHOD_DEVX_QUERY_EQN));
 
 static DECLARE_UVERBS_NAMED_OBJECT(MLX5_IB_OBJECT_DEVX_OBJ,
 	&UVERBS_TYPE_ALLOC_IDR(0, devx_obj_cleanup),

include/uapi/rdma/mlx5_user_ioctl_cmds.h

@@ -48,6 +48,7 @@ enum mlx5_ib_alloc_dm_attrs {
 enum mlx5_ib_devx_methods {
 	MLX5_IB_METHOD_DEVX_OTHER  = (1U << UVERBS_ID_NS_SHIFT),
 	MLX5_IB_METHOD_DEVX_QUERY_UAR,
+	MLX5_IB_METHOD_DEVX_QUERY_EQN,
 };
 
 enum  mlx5_ib_devx_other_attrs {
@@ -82,6 +83,11 @@ enum mlx5_ib_devx_obj_query_attrs {
 	MLX5_IB_ATTR_DEVX_OBJ_QUERY_CMD_OUT,
 };
 
+enum  mlx5_ib_devx_query_eqn_attrs {
+	MLX5_IB_ATTR_DEVX_QUERY_EQN_USER_VEC = (1U << UVERBS_ID_NS_SHIFT),
+	MLX5_IB_ATTR_DEVX_QUERY_EQN_DEV_EQN,
+};
+
 enum mlx5_ib_devx_obj_methods {
 	MLX5_IB_METHOD_DEVX_OBJ_CREATE = (1U << UVERBS_ID_NS_SHIFT),
 	MLX5_IB_METHOD_DEVX_OBJ_DESTROY,