On Mon, Apr 3, 2023 at 2:47 PM Eli Cohen <elic@xxxxxxxxxx> wrote:
>
>
> On 03/04/2023 8:01, Jason Wang wrote:
> > On Sun, Apr 2, 2023 at 10:15 PM Eli Cohen <elic@xxxxxxxxxx> wrote:
> >> Current code ignores link state updates if VIRTIO_NET_F_STATUS was not
> >> negotiated. However, link state updates could be received before feature
> >> negotiation was completed , therefore causing link state events to be
> >> lost, possibly leaving the link state down.
> >>
> >> Modify the code so link state notifier is registered only when
> >> VIRTIO_NET_F_STATUS flips from 0 to 1 and unregister it on driver reset
> >> or suspend.
> >>
> >> Fixes: 033779a708f0 ("vdpa/mlx5: make MTU/STATUS presence conditional on feature bits")
> >> Signed-off-by: Eli Cohen <elic@xxxxxxxxxx>
> >> ---
> >> v2 -> v3
> >> Only register the link event notifier when VIRTIO_NET_F_STATUS is
> >> negotiated.
> >>
> >> drivers/vdpa/mlx5/net/mlx5_vnet.c | 200 +++++++++++++++++-------------
> >> 1 file changed, 112 insertions(+), 88 deletions(-)
> >>
> >> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> >> index 317cef9b7813..9b1432e22540 100644
> >> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> >> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> >> @@ -2322,10 +2322,115 @@ static void update_cvq_info(struct mlx5_vdpa_dev *mvdev)
> >> }
> >> }
> >>
> >> +static u8 query_vport_state(struct mlx5_core_dev *mdev, u8 opmod, u16 vport)
> >> +{
> >> + u32 out[MLX5_ST_SZ_DW(query_vport_state_out)] = {};
> >> + u32 in[MLX5_ST_SZ_DW(query_vport_state_in)] = {};
> >> + int err;
> >> +
> >> + MLX5_SET(query_vport_state_in, in, opcode, MLX5_CMD_OP_QUERY_VPORT_STATE);
> >> + MLX5_SET(query_vport_state_in, in, op_mod, opmod);
> >> + MLX5_SET(query_vport_state_in, in, vport_number, vport);
> >> + if (vport)
> >> + MLX5_SET(query_vport_state_in, in, other_vport, 1);
> >> +
> >> + err = mlx5_cmd_exec_inout(mdev, query_vport_state, in, out);
> >> + if (err)
> >> + return 0;
> >> +
> >> + return MLX5_GET(query_vport_state_out, out, state);
> >> +}
> >> +
> >> +static bool get_link_state(struct mlx5_vdpa_dev *mvdev)
> >> +{
> >> + if (query_vport_state(mvdev->mdev, MLX5_VPORT_STATE_OP_MOD_VNIC_VPORT, 0) ==
> >> + VPORT_STATE_UP)
> >> + return true;
> >> +
> >> + return false;
> >> +}
> >> +
> >> +static void update_carrier(struct work_struct *work)
> >> +{
> >> + struct mlx5_vdpa_wq_ent *wqent;
> >> + struct mlx5_vdpa_dev *mvdev;
> >> + struct mlx5_vdpa_net *ndev;
> >> +
> >> + wqent = container_of(work, struct mlx5_vdpa_wq_ent, work);
> >> + mvdev = wqent->mvdev;
> >> + ndev = to_mlx5_vdpa_ndev(mvdev);
> >> + if (get_link_state(mvdev))
> >> + ndev->config.status |= cpu_to_mlx5vdpa16(mvdev, VIRTIO_NET_S_LINK_UP);
> >> + else
> >> + ndev->config.status &= cpu_to_mlx5vdpa16(mvdev, ~VIRTIO_NET_S_LINK_UP);
> >> +
> >> + if (ndev->nb_registered && ndev->config_cb.callback)
> > It looks to me nb_registered is accessed without synchronization. Or
> > we don't even need to check that if we do:
> >
> > unregister();
> > flush_workqueue();
> >
> > which has been done in unregister_link_notifier().
> >
> >> + ndev->config_cb.callback(ndev->config_cb.private);
> >> +
> >> + kfree(wqent);
> >> +}
> >> +
> >> +static int queue_link_work(struct mlx5_vdpa_net *ndev)
> >> +{
> >> + struct mlx5_vdpa_wq_ent *wqent;
> >> +
> >> + wqent = kzalloc(sizeof(*wqent), GFP_ATOMIC);
> >> + if (!wqent)
> >> + return -ENOMEM;
> >> +
> >> + wqent->mvdev = &ndev->mvdev;
> >> + INIT_WORK(&wqent->work, update_carrier);
> >> + queue_work(ndev->mvdev.wq, &wqent->work);
> >> + return 0;
> >> +}
> >> +
> >> +static int event_handler(struct notifier_block *nb, unsigned long event, void *param)
> >> +{
> >> + struct mlx5_vdpa_net *ndev = container_of(nb, struct mlx5_vdpa_net, nb);
> >> + struct mlx5_eqe *eqe = param;
> >> + int ret = NOTIFY_DONE;
> >> +
> >> + if (event == MLX5_EVENT_TYPE_PORT_CHANGE) {
> >> + switch (eqe->sub_type) {
> >> + case MLX5_PORT_CHANGE_SUBTYPE_DOWN:
> >> + case MLX5_PORT_CHANGE_SUBTYPE_ACTIVE:
> >> + if (queue_link_work(ndev))
> >> + return NOTIFY_DONE;
> >> +
> >> + ret = NOTIFY_OK;
> >> + break;
> >> + default:
> >> + return NOTIFY_DONE;
> >> + }
> >> + return ret;
> >> + }
> >> + return ret;
> >> +}
> >> +
> >> +static void register_link_notifier(struct mlx5_vdpa_net *ndev)
> >> +{
> >> + ndev->nb.notifier_call = event_handler;
> >> + mlx5_notifier_register(ndev->mvdev.mdev, &ndev->nb);
> >> + ndev->nb_registered = true;
> >> + queue_link_work(ndev);
> >> +}
> >> +
> >> +static void unregister_link_notifier(struct mlx5_vdpa_net *ndev)
> >> +{
> >> + if (!ndev->nb_registered)
> >> + return;
> >> +
> >> + ndev->nb_registered = false;
> >> + mlx5_notifier_unregister(ndev->mvdev.mdev, &ndev->nb);
> >> + if (ndev->mvdev.wq)
> > Under which case could we hit mvdev.wq = NULL?
> >
> > (We call unregister_link_notifier() before setting mq to NULL during
> > device del).
> >
> >> + flush_workqueue(ndev->mvdev.wq);
> >> +}
> >> +
> >> static int mlx5_vdpa_set_driver_features(struct vdpa_device *vdev, u64 features)
> >> {
> >> struct mlx5_vdpa_dev *mvdev = to_mvdev(vdev);
> >> struct mlx5_vdpa_net *ndev = to_mlx5_vdpa_ndev(mvdev);
> >> + u64 old;
> >> int err;
> >>
> >> print_features(mvdev, features, true);
> >> @@ -2334,7 +2439,11 @@ static int mlx5_vdpa_set_driver_features(struct vdpa_device *vdev, u64 features)
> >> if (err)
> >> return err;
> >>
> >> + old = ndev->mvdev.actual_features;
> >> ndev->mvdev.actual_features = features & ndev->mvdev.mlx_features;
> >> + if (~old & ndev->mvdev.actual_features & BIT_ULL(VIRTIO_NET_F_STATUS))
> >> + register_link_notifier(ndev);
> >> +
> > I still think it's better to move this check during set_status.
> > Otherwise, we may have a small window where the link update event is
> > sent before DRIVER_OK.
> How about setup_driver() and teardown driver to register/unregister the
> notfier?
If I understand the code correctly, setup_driver() will be called by
set_map() which could be called before DRIVER_OK.
Thanks
> >
> > Thanks
> >
> >> if (ndev->mvdev.actual_features & BIT_ULL(VIRTIO_NET_F_MQ))
> >> ndev->rqt_size = mlx5vdpa16_to_cpu(mvdev, ndev->config.max_virtqueue_pairs);
> >> else
> >> @@ -2629,6 +2738,7 @@ static int mlx5_vdpa_reset(struct vdpa_device *vdev)
> >> mlx5_vdpa_info(mvdev, "performing device reset\n");
> >>
> >> down_write(&ndev->reslock);
> >> + unregister_link_notifier(ndev);
> >> teardown_driver(ndev);
> >> clear_vqs_ready(ndev);
> >> mlx5_vdpa_destroy_mr(&ndev->mvdev);
> >> @@ -2883,9 +2993,7 @@ static int mlx5_vdpa_suspend(struct vdpa_device *vdev)
> >> mlx5_vdpa_info(mvdev, "suspending device\n");
> >>
> >> down_write(&ndev->reslock);
> >> - ndev->nb_registered = false;
> >> - mlx5_notifier_unregister(mvdev->mdev, &ndev->nb);
> >> - flush_workqueue(ndev->mvdev.wq);
> >> + unregister_link_notifier(ndev);
> >> for (i = 0; i < ndev->cur_num_vqs; i++) {
> >> mvq = &ndev->vqs[i];
> >> suspend_vq(ndev, mvq);
> >> @@ -3022,84 +3130,6 @@ struct mlx5_vdpa_mgmtdev {
> >> struct mlx5_vdpa_net *ndev;
> >> };
> >>
> >> -static u8 query_vport_state(struct mlx5_core_dev *mdev, u8 opmod, u16 vport)
> >> -{
> >> - u32 out[MLX5_ST_SZ_DW(query_vport_state_out)] = {};
> >> - u32 in[MLX5_ST_SZ_DW(query_vport_state_in)] = {};
> >> - int err;
> >> -
> >> - MLX5_SET(query_vport_state_in, in, opcode, MLX5_CMD_OP_QUERY_VPORT_STATE);
> >> - MLX5_SET(query_vport_state_in, in, op_mod, opmod);
> >> - MLX5_SET(query_vport_state_in, in, vport_number, vport);
> >> - if (vport)
> >> - MLX5_SET(query_vport_state_in, in, other_vport, 1);
> >> -
> >> - err = mlx5_cmd_exec_inout(mdev, query_vport_state, in, out);
> >> - if (err)
> >> - return 0;
> >> -
> >> - return MLX5_GET(query_vport_state_out, out, state);
> >> -}
> >> -
> >> -static bool get_link_state(struct mlx5_vdpa_dev *mvdev)
> >> -{
> >> - if (query_vport_state(mvdev->mdev, MLX5_VPORT_STATE_OP_MOD_VNIC_VPORT, 0) ==
> >> - VPORT_STATE_UP)
> >> - return true;
> >> -
> >> - return false;
> >> -}
> >> -
> >> -static void update_carrier(struct work_struct *work)
> >> -{
> >> - struct mlx5_vdpa_wq_ent *wqent;
> >> - struct mlx5_vdpa_dev *mvdev;
> >> - struct mlx5_vdpa_net *ndev;
> >> -
> >> - wqent = container_of(work, struct mlx5_vdpa_wq_ent, work);
> >> - mvdev = wqent->mvdev;
> >> - ndev = to_mlx5_vdpa_ndev(mvdev);
> >> - if (get_link_state(mvdev))
> >> - ndev->config.status |= cpu_to_mlx5vdpa16(mvdev, VIRTIO_NET_S_LINK_UP);
> >> - else
> >> - ndev->config.status &= cpu_to_mlx5vdpa16(mvdev, ~VIRTIO_NET_S_LINK_UP);
> >> -
> >> - if (ndev->nb_registered && ndev->config_cb.callback)
> >> - ndev->config_cb.callback(ndev->config_cb.private);
> >> -
> >> - kfree(wqent);
> >> -}
> >> -
> >> -static int event_handler(struct notifier_block *nb, unsigned long event, void *param)
> >> -{
> >> - struct mlx5_vdpa_net *ndev = container_of(nb, struct mlx5_vdpa_net, nb);
> >> - struct mlx5_eqe *eqe = param;
> >> - int ret = NOTIFY_DONE;
> >> - struct mlx5_vdpa_wq_ent *wqent;
> >> -
> >> - if (event == MLX5_EVENT_TYPE_PORT_CHANGE) {
> >> - if (!(ndev->mvdev.actual_features & BIT_ULL(VIRTIO_NET_F_STATUS)))
> >> - return NOTIFY_DONE;
> >> - switch (eqe->sub_type) {
> >> - case MLX5_PORT_CHANGE_SUBTYPE_DOWN:
> >> - case MLX5_PORT_CHANGE_SUBTYPE_ACTIVE:
> >> - wqent = kzalloc(sizeof(*wqent), GFP_ATOMIC);
> >> - if (!wqent)
> >> - return NOTIFY_DONE;
> >> -
> >> - wqent->mvdev = &ndev->mvdev;
> >> - INIT_WORK(&wqent->work, update_carrier);
> >> - queue_work(ndev->mvdev.wq, &wqent->work);
> >> - ret = NOTIFY_OK;
> >> - break;
> >> - default:
> >> - return NOTIFY_DONE;
> >> - }
> >> - return ret;
> >> - }
> >> - return ret;
> >> -}
> >> -
> >> static int config_func_mtu(struct mlx5_core_dev *mdev, u16 mtu)
> >> {
> >> int inlen = MLX5_ST_SZ_BYTES(modify_nic_vport_context_in);
> >> @@ -3282,9 +3312,6 @@ static int mlx5_vdpa_dev_add(struct vdpa_mgmt_dev *v_mdev, const char *name,
> >> goto err_res2;
> >> }
> >>
> >> - ndev->nb.notifier_call = event_handler;
> >> - mlx5_notifier_register(mdev, &ndev->nb);
> >> - ndev->nb_registered = true;
> >> mvdev->vdev.mdev = &mgtdev->mgtdev;
> >> err = _vdpa_register_device(&mvdev->vdev, max_vqs + 1);
> >> if (err)
> >> @@ -3318,10 +3345,7 @@ static void mlx5_vdpa_dev_del(struct vdpa_mgmt_dev *v_mdev, struct vdpa_device *
> >>
> >> mlx5_vdpa_remove_debugfs(ndev->debugfs);
> >> ndev->debugfs = NULL;
> >> - if (ndev->nb_registered) {
> >> - ndev->nb_registered = false;
> >> - mlx5_notifier_unregister(mvdev->mdev, &ndev->nb);
> >> - }
> >> + unregister_link_notifier(ndev);
> >> wq = mvdev->wq;
> >> mvdev->wq = NULL;
> >> destroy_workqueue(wq);
> >> --
> >> 2.38.1
> >>
>
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