Messages in this thread | | | Subject | Re: [PATCH 1/2] vdpa/mlx5: Avoid unnecessary query virtqueue | From | Jason Wang <> | Date | Tue, 2 Feb 2021 14:02:25 +0800 |
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On 2021/2/2 下午12:15, Si-Wei Liu wrote: > On Mon, Feb 1, 2021 at 7:13 PM Jason Wang <jasowang@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.kernel@gmail.com> wrote: >>>> On Thu, Jan 28, 2021 at 5:46 AM Eli Cohen <elic@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@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.
Eli may know more, my understanding is that, during memory hotplut, qemu need to propagate new memory mappings via set_map(). For mellanox, it means it needs to rebuild memory keys, so the virtqueue needs to be suspended.
Thanks
> > -Siwei > >> Thanks >> >> >>>> -Siwei >>>> >>>> >>>>> Signed-off-by: Eli Cohen <elic@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 >>>>>
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