vfio/mlx5: Manage error scenarios on tracker

Handle async error events and health/recovery flow to safely stop the
tracker upon error scenarios.

Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
Link: https://lore.kernel.org/r/20220908183448.195262-10-yishaih@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

drivers/vfio/pci/mlx5/cmd.c

@@ -70,6 +70,13 @@ int mlx5vf_cmd_query_vhca_migration_state(struct mlx5vf_pci_core_device *mvdev,
 	return 0;
 }
 
+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 */
+	mvdev->tracker.is_err = true;
+	complete(&mvdev->tracker_comp);
+}
+
 static int mlx5fv_vf_event(struct notifier_block *nb,
 			   unsigned long event, void *data)
 {
@@ -100,6 +107,8 @@ void mlx5vf_cmd_close_migratable(struct mlx5vf_pci_core_device *mvdev)
 	if (!mvdev->migrate_cap)
 		return;
 
+	/* Must be done outside the lock to let it progress */
+	set_tracker_error(mvdev);
 	mutex_lock(&mvdev->state_mutex);
 	mlx5vf_disable_fds(mvdev);
 	_mlx5vf_free_page_tracker_resources(mvdev);
@@ -619,6 +628,47 @@ static void mlx5vf_destroy_cq(struct mlx5_core_dev *mdev,
 	mlx5_db_free(mdev, &cq->db);
 }
 
+static void mlx5vf_cq_event(struct mlx5_core_cq *mcq, enum mlx5_event type)
+{
+	if (type != MLX5_EVENT_TYPE_CQ_ERROR)
+		return;
+
+	set_tracker_error(container_of(mcq, struct mlx5vf_pci_core_device,
+				       tracker.cq.mcq));
+}
+
+static int mlx5vf_event_notifier(struct notifier_block *nb, unsigned long type,
+				 void *data)
+{
+	struct mlx5_vhca_page_tracker *tracker =
+		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 *eqe = data;
+	u8 event_type = (u8)type;
+	u8 queue_type;
+	int qp_num;
+
+	switch (event_type) {
+	case MLX5_EVENT_TYPE_WQ_CATAS_ERROR:
+	case MLX5_EVENT_TYPE_WQ_ACCESS_ERROR:
+	case MLX5_EVENT_TYPE_WQ_INVAL_REQ_ERROR:
+		queue_type = eqe->data.qp_srq.type;
+		if (queue_type != MLX5_EVENT_QUEUE_TYPE_QP)
+			break;
+		qp_num = be32_to_cpu(eqe->data.qp_srq.qp_srq_n) & 0xffffff;
+		if (qp_num != tracker->host_qp->qpn &&
+		    qp_num != tracker->fw_qp->qpn)
+			break;
+		set_tracker_error(mvdev);
+		break;
+	default:
+		break;
+	}
+
+	return NOTIFY_OK;
+}
+
 static void mlx5vf_cq_complete(struct mlx5_core_cq *mcq,
 			       struct mlx5_eqe *eqe)
 {
@@ -680,6 +730,7 @@ static int mlx5vf_create_cq(struct mlx5_core_dev *mdev,
 	pas = (__be64 *)MLX5_ADDR_OF(create_cq_in, in, pas);
 	mlx5_fill_page_frag_array(&cq->buf.frag_buf, pas);
 	cq->mcq.comp = mlx5vf_cq_complete;
+	cq->mcq.event = mlx5vf_cq_event;
 	err = mlx5_core_create_cq(mdev, &cq->mcq, in, inlen, out, sizeof(out));
 	if (err)
 		goto err_vec;
@@ -1014,6 +1065,7 @@ _mlx5vf_free_page_tracker_resources(struct mlx5vf_pci_core_device *mvdev)
 
 	WARN_ON(mvdev->mdev_detach);
 
+	mlx5_eq_notifier_unregister(mdev, &tracker->nb);
 	mlx5vf_cmd_destroy_tracker(mdev, tracker->id);
 	mlx5vf_destroy_qp(mdev, tracker->fw_qp);
 	mlx5vf_free_qp_recv_resources(mdev, tracker->host_qp);
@@ -1127,6 +1179,8 @@ int mlx5vf_start_page_tracker(struct vfio_device *vdev,
 	if (err)
 		goto err_activate;
 
+	MLX5_NB_INIT(&tracker->nb, mlx5vf_event_notifier, NOTIFY_ANY);
+	mlx5_eq_notifier_register(mdev, &tracker->nb);
 	*page_size = host_qp->tracked_page_size;
 	mvdev->log_active = true;
 	mlx5vf_state_mutex_unlock(mvdev);
@@ -1273,7 +1327,8 @@ int mlx5vf_tracker_read_and_clear(struct vfio_device *vdev, unsigned long iova,
 		goto end;
 
 	tracker->status = MLX5_PAGE_TRACK_STATE_REPORTING;
-	while (tracker->status == MLX5_PAGE_TRACK_STATE_REPORTING) {
+	while (tracker->status == MLX5_PAGE_TRACK_STATE_REPORTING &&
+	       !tracker->is_err) {
 		poll_err = mlx5vf_cq_poll_one(cq, tracker->host_qp, dirty,
 					      &tracker->status);
 		if (poll_err == CQ_EMPTY) {
@@ -1294,8 +1349,10 @@ int mlx5vf_tracker_read_and_clear(struct vfio_device *vdev, unsigned long iova,
 	}
 
 	if (tracker->status == MLX5_PAGE_TRACK_STATE_ERROR)
-		err = -EIO;
+		tracker->is_err = true;
 
+	if (tracker->is_err)
+		err = -EIO;
 end:
 	mlx5vf_state_mutex_unlock(mvdev);
 	return err;

drivers/vfio/pci/mlx5/cmd.h

@@ -82,10 +82,12 @@ struct mlx5_vhca_qp {
 struct mlx5_vhca_page_tracker {
 	u32 id;
 	u32 pdn;
+	u8 is_err:1;
 	struct mlx5_uars_page *uar;
 	struct mlx5_vhca_cq cq;
 	struct mlx5_vhca_qp *host_qp;
 	struct mlx5_vhca_qp *fw_qp;
+	struct mlx5_nb nb;
 	int status;
 };