vfio/mlx5: Add support for tracker object change event

Add support for tracker object change event by referring to its
MLX5_EVENT_TYPE_OBJECT_CHANGE event when occurs.

This lets the driver recognize whether the firmware moved the tracker
object to an error state.

In that case, the driver will skip/block any usage of that object
including an early exit in case the object was previously marked with an
error.

This functionality also covers the case when no CQE is delivered as of
the error state.

The driver was adapted to the device specification to handle the above.

Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Acked-by: Leon Romanovsky <leon@kernel.org>
Link: https://lore.kernel.org/r/20240205124828.232701-3-yishaih@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

Author: Yishai Hadas

drivers/vfio/pci/mlx5/cmd.c

@@ -149,6 +149,12 @@ int mlx5vf_cmd_query_vhca_migration_state(struct mlx5vf_pci_core_device *mvdev,
 	return 0;
 }
 
+static void set_tracker_change_event(struct mlx5vf_pci_core_device *mvdev)
+{
+	mvdev->tracker.object_changed = true;
+	complete(&mvdev->tracker_comp);
+}
+
 static void set_tracker_error(struct mlx5vf_pci_core_device *mvdev)
 {
 	/* Mark the tracker under an error and wake it up if it's running */
@@ -900,6 +906,29 @@ static int mlx5vf_cmd_modify_tracker(struct mlx5_core_dev *mdev,
 	return mlx5_cmd_exec(mdev, in, sizeof(in), out, sizeof(out));
 }
 
+static int mlx5vf_cmd_query_tracker(struct mlx5_core_dev *mdev,
+				    struct mlx5_vhca_page_tracker *tracker)
+{
+	u32 out[MLX5_ST_SZ_DW(query_page_track_obj_out)] = {};
+	u32 in[MLX5_ST_SZ_DW(general_obj_in_cmd_hdr)] = {};
+	void *obj_context;
+	void *cmd_hdr;
+	int err;
+
+	cmd_hdr = MLX5_ADDR_OF(modify_page_track_obj_in, in, general_obj_in_cmd_hdr);
+	MLX5_SET(general_obj_in_cmd_hdr, cmd_hdr, opcode, MLX5_CMD_OP_QUERY_GENERAL_OBJECT);
+	MLX5_SET(general_obj_in_cmd_hdr, cmd_hdr, obj_type, MLX5_OBJ_TYPE_PAGE_TRACK);
+	MLX5_SET(general_obj_in_cmd_hdr, cmd_hdr, obj_id, tracker->id);
+
+	err = mlx5_cmd_exec(mdev, in, sizeof(in), out, sizeof(out));
+	if (err)
+		return err;
+
+	obj_context = MLX5_ADDR_OF(query_page_track_obj_out, out, obj_context);
+	tracker->status = MLX5_GET(page_track, obj_context, state);
+	return 0;
+}
+
 static int alloc_cq_frag_buf(struct mlx5_core_dev *mdev,
 			     struct mlx5_vhca_cq_buf *buf, int nent,
 			     int cqe_size)
@@ -957,9 +986,11 @@ static int mlx5vf_event_notifier(struct notifier_block *nb, unsigned long type,
 		mlx5_nb_cof(nb, struct mlx5_vhca_page_tracker, nb);
 	struct mlx5vf_pci_core_device *mvdev = container_of(
 		tracker, struct mlx5vf_pci_core_device, tracker);
+	struct mlx5_eqe_obj_change *object;
 	struct mlx5_eqe *eqe = data;
 	u8 event_type = (u8)type;
 	u8 queue_type;
+	u32 obj_id;
 	int qp_num;
 
 	switch (event_type) {
@@ -975,6 +1006,12 @@ static int mlx5vf_event_notifier(struct notifier_block *nb, unsigned long type,
 			break;
 		set_tracker_error(mvdev);
 		break;
+	case MLX5_EVENT_TYPE_OBJECT_CHANGE:
+		object = &eqe->data.obj_change;
+		obj_id = be32_to_cpu(object->obj_id);
+		if (obj_id == tracker->id)
+			set_tracker_change_event(mvdev);
+		break;
 	default:
 		break;
 	}
@@ -1634,6 +1671,11 @@ int mlx5vf_tracker_read_and_clear(struct vfio_device *vdev, unsigned long iova,
 		goto end;
 	}
 
+	if (tracker->is_err) {
+		err = -EIO;
+		goto end;
+	}
+
 	mdev = mvdev->mdev;
 	err = mlx5vf_cmd_modify_tracker(mdev, tracker->id, iova, length,
 					MLX5_PAGE_TRACK_STATE_REPORTING);
@@ -1652,6 +1694,12 @@ int mlx5vf_tracker_read_and_clear(struct vfio_device *vdev, unsigned long iova,
 						      dirty, &tracker->status);
 			if (poll_err == CQ_EMPTY) {
 				wait_for_completion(&mvdev->tracker_comp);
+				if (tracker->object_changed) {
+					tracker->object_changed = false;
+					err = mlx5vf_cmd_query_tracker(mdev, tracker);
+					if (err)
+						goto end;
+				}
 				continue;
 			}
 		}

drivers/vfio/pci/mlx5/cmd.h

@@ -162,6 +162,7 @@ struct mlx5_vhca_page_tracker {
 	u32 id;
 	u32 pdn;
 	u8 is_err:1;
+	u8 object_changed:1;
 	struct mlx5_uars_page *uar;
 	struct mlx5_vhca_cq cq;
 	struct mlx5_vhca_qp *host_qp;