Messages in this thread | | | From | Eli Cohen <> | Subject | RE: [PATCH RESEND V2 1/3] vdpa: mlx5: prevent cvq work from hogging CPU | Date | Wed, 30 Mar 2022 06:47:48 +0000 |
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> From: Jason Wang <jasowang@redhat.com> > Sent: Tuesday, March 29, 2022 7:21 AM > To: jasowang@redhat.com; mst@redhat.com > Cc: Eli Cohen <elic@nvidia.com>; hdanton@sina.com; virtualization@lists.linux-foundation.org; linux-kernel@vger.kernel.org > Subject: [PATCH RESEND V2 1/3] vdpa: mlx5: prevent cvq work from hogging CPU > > A userspace triggerable infinite loop could happen in > mlx5_cvq_kick_handler() if userspace keeps sending a huge amount of > cvq requests. > > Fixing this by introducing a quota and re-queue the work if we're out > of the budget (currently the implicit budget is one) . While at it, > using a per device work struct to avoid on demand memory allocation > for cvq. > > Fixes: 5262912ef3cfc ("vdpa/mlx5: Add support for control VQ and MAC setting") > Signed-off-by: Jason Wang <jasowang@redhat.com>
Acked-by: Eli Cohen <elic@nvidia.com>
> --- > Changes since V1: > - Using 1 as the budget > --- > drivers/vdpa/mlx5/net/mlx5_vnet.c | 21 +++++++++------------ > 1 file changed, 9 insertions(+), 12 deletions(-) > > diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c > index d0f91078600e..b2afd2b6fbca 100644 > --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c > +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c > @@ -163,6 +163,7 @@ struct mlx5_vdpa_net { > u32 cur_num_vqs; > struct notifier_block nb; > struct vdpa_callback config_cb; > + struct mlx5_vdpa_wq_ent cvq_ent; > }; > > static void free_resources(struct mlx5_vdpa_net *ndev); > @@ -1616,10 +1617,10 @@ static void mlx5_cvq_kick_handler(struct work_struct *work) > ndev = to_mlx5_vdpa_ndev(mvdev); > cvq = &mvdev->cvq; > if (!(ndev->mvdev.actual_features & BIT_ULL(VIRTIO_NET_F_CTRL_VQ))) > - goto out; > + return; > > if (!cvq->ready) > - goto out; > + return; > > while (true) { > err = vringh_getdesc_iotlb(&cvq->vring, &cvq->riov, &cvq->wiov, &cvq->head, > @@ -1653,9 +1654,10 @@ static void mlx5_cvq_kick_handler(struct work_struct *work) > > if (vringh_need_notify_iotlb(&cvq->vring)) > vringh_notify(&cvq->vring); > + > + queue_work(mvdev->wq, &wqent->work); > + break; > } > -out: > - kfree(wqent); > } > > static void mlx5_vdpa_kick_vq(struct vdpa_device *vdev, u16 idx) > @@ -1663,7 +1665,6 @@ static void mlx5_vdpa_kick_vq(struct vdpa_device *vdev, u16 idx) > struct mlx5_vdpa_dev *mvdev = to_mvdev(vdev); > struct mlx5_vdpa_net *ndev = to_mlx5_vdpa_ndev(mvdev); > struct mlx5_vdpa_virtqueue *mvq; > - struct mlx5_vdpa_wq_ent *wqent; > > if (!is_index_valid(mvdev, idx)) > return; > @@ -1672,13 +1673,7 @@ static void mlx5_vdpa_kick_vq(struct vdpa_device *vdev, u16 idx) > if (!mvdev->cvq.ready) > return; > > - wqent = kzalloc(sizeof(*wqent), GFP_ATOMIC); > - if (!wqent) > - return; > - > - wqent->mvdev = mvdev; > - INIT_WORK(&wqent->work, mlx5_cvq_kick_handler); > - queue_work(mvdev->wq, &wqent->work); > + queue_work(mvdev->wq, &ndev->cvq_ent.work); > return; > } > > @@ -2668,6 +2663,8 @@ static int mlx5_vdpa_dev_add(struct vdpa_mgmt_dev *v_mdev, const char *name, > if (err) > goto err_mr; > > + ndev->cvq_ent.mvdev = mvdev; > + INIT_WORK(&ndev->cvq_ent.work, mlx5_cvq_kick_handler); > mvdev->wq = create_singlethread_workqueue("mlx5_vdpa_wq"); > if (!mvdev->wq) { > err = -ENOMEM; > -- > 2.18.1
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