On Mon, Feb 1, 2021 at 7:13 PM Jason Wang <jasow...@redhat.com> wrote:
>
>
> On 2021/2/2 上午3:17, Si-Wei Liu wrote:
> > On Mon, Feb 1, 2021 at 10:51 AM Si-Wei Liu <siwliu.ker...@gmail.com> wrote:
> >> On Thu, Jan 28, 2021 at 5:46 AM Eli Cohen <e...@nvidia.com> wrote:
> >>> suspend_vq should only suspend the VQ on not save the current available
> >>> index. This is done when a change of map occurs when the driver calls
> >>> save_channel_info().
> >> Hmmm, suspend_vq() is also called by teardown_vq(), the latter of
> >> which doesn't save the available index as save_channel_info() doesn't
> >> get called in that path at all. How does it handle the case that
> >> aget_vq_state() is called from userspace (e.g. QEMU) while the
> >> hardware VQ object was torn down, but userspace still wants to access
> >> the queue index?
> >>
> >> Refer to
> >> https://lore.kernel.org/netdev/1601583511-15138-1-git-send-email-si-wei....@oracle.com/
> >>
> >> vhost VQ 0 ring restore failed: -1: Resource temporarily unavailable (11)
> >> vhost VQ 1 ring restore failed: -1: Resource temporarily unavailable (11)
> >>
> >> QEMU will complain with the above warning while VM is being rebooted
> >> or shut down.
> >>
> >> Looks to me either the kernel driver should cover this requirement, or
> >> the userspace has to bear the burden in saving the index and not call
> >> into kernel if VQ is destroyed.
> > Actually, the userspace doesn't have the insights whether virt queue
> > will be destroyed if just changing the device status via set_status().
> > Looking at other vdpa driver in tree i.e. ifcvf it doesn't behave like
> > so. Hence this still looks to me to be Mellanox specifics and
> > mlx5_vdpa implementation detail that shouldn't expose to userspace.
>
>
> So I think we can simply drop this patch?
Yep, I think so. To be honest I don't know why it has anything to do
with the memory hotplug issue.
-Siwei
>
> Thanks
>
>
> >> -Siwei
> >>
> >>
> >>> Signed-off-by: Eli Cohen <e...@nvidia.com>
> >>> ---
> >>> drivers/vdpa/mlx5/net/mlx5_vnet.c | 8 --------
> >>> 1 file changed, 8 deletions(-)
> >>>
> >>> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> >>> b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> >>> index 88dde3455bfd..549ded074ff3 100644
> >>> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> >>> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> >>> @@ -1148,8 +1148,6 @@ static int setup_vq(struct mlx5_vdpa_net *ndev,
> >>> struct mlx5_vdpa_virtqueue *mvq)
> >>>
> >>> static void suspend_vq(struct mlx5_vdpa_net *ndev, struct
> >>> mlx5_vdpa_virtqueue *mvq)
> >>> {
> >>> - struct mlx5_virtq_attr attr;
> >>> -
> >>> if (!mvq->initialized)
> >>> return;
> >>>
> >>> @@ -1158,12 +1156,6 @@ static void suspend_vq(struct mlx5_vdpa_net *ndev,
> >>> struct mlx5_vdpa_virtqueue *m
> >>>
> >>> if (modify_virtqueue(ndev, mvq,
> >>> MLX5_VIRTIO_NET_Q_OBJECT_STATE_SUSPEND))
> >>> mlx5_vdpa_warn(&ndev->mvdev, "modify to suspend
> >>> failed\n");
> >>> -
> >>> - if (query_virtqueue(ndev, mvq, &attr)) {
> >>> - mlx5_vdpa_warn(&ndev->mvdev, "failed to query
> >>> virtqueue\n");
> >>> - return;
> >>> - }
> >>> - mvq->avail_idx = attr.available_index;
> >>> }
> >>>
> >>> static void suspend_vqs(struct mlx5_vdpa_net *ndev)
> >>> --
> >>> 2.29.2
> >>>
>
