Michael S. Tsirkin
2021-Feb-02 14:06 UTC
[PATCH 1/2] vdpa/mlx5: Avoid unnecessary query virtqueue
On Tue, Feb 02, 2021 at 09:00:55AM +0200, Eli Cohen wrote:> On Mon, Feb 01, 2021 at 08:15:29PM -0800, Si-Wei Liu wrote: > > On Mon, Feb 1, 2021 at 7:13 PM Jason Wang <jasowang at redhat.com> wrote: > > > > > > > > > On 2021/2/2 ??3:17, Si-Wei Liu wrote: > > > > On Mon, Feb 1, 2021 at 10:51 AM Si-Wei Liu <siwliu.kernel at gmail.com> wrote: > > > >> On Thu, Jan 28, 2021 at 5:46 AM Eli Cohen <elic at 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.liu at 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. > > No relation. That's why I put them in two different patches. Only the > second one is the fix as I stated in the cover letter. > > Anyway, let's just take the second patch. > > Michael, do you need me to send PATCH 2 again as a single patch or can > you just take it?Pls post fixes separately. Thanks!> > > > > -Siwei > > > > > > > > Thanks > > > > > > > > > >> -Siwei > > > >> > > > >> > > > >>> Signed-off-by: Eli Cohen <elic at 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 > > > >>> > > >