lkml.org 
[lkml]   [2021]   [Jun]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v8 09/10] vduse: Introduce VDUSE - vDPA Device in Userspace
From
Date

在 2021/6/24 下午5:16, Yongji Xie 写道:
> On Thu, Jun 24, 2021 at 4:14 PM Jason Wang <jasowang@redhat.com> wrote:
>>
>> 在 2021/6/24 下午12:46, Yongji Xie 写道:
>>>> So we need to deal with both FEATURES_OK and reset, but probably not
>>>> DRIVER_OK.
>>>>
>>> OK, I see. Thanks for the explanation. One more question is how about
>>> clearing the corresponding status bit in get_status() rather than
>>> making set_status() fail. Since the spec recommends this way for
>>> validation which is done in virtio_dev_remove() and
>>> virtio_finalize_features().
>>>
>>> Thanks,
>>> Yongji
>>>
>> I think you can. Or it would be even better that we just don't set the
>> bit during set_status().
>>
> Yes, that's what I mean.
>
>> I just realize that in vdpa_reset() we had:
>>
>> static inline void vdpa_reset(struct vdpa_device *vdev)
>> {
>> const struct vdpa_config_ops *ops = vdev->config;
>>
>> vdev->features_valid = false;
>> ops->set_status(vdev, 0);
>> }
>>
>> We probably need to add the synchronization here. E.g re-read with a
>> timeout.
>>
> Looks like the timeout is already in set_status().


Do you mean the VDUSE's implementation?


> Do we really need a
> duplicated one here?


1) this is the timeout at the vDPA layer instead of the VDUSE layer.
2) it really depends on what's the meaning of the timeout for set_status
of VDUSE.

Do we want:

2a) for set_status(): relay the message to userspace and wait for the
userspace to quiescence the datapath

or

2b) for set_status(): simply relay the message to userspace, reply is no
needed. Userspace will use a command to update the status when the
datapath is stop. The the status could be fetched via get_stats().

2b looks more spec complaint.

> And how to handle failure? Adding a return value
> to virtio_config_ops->reset() and passing the error to the upper
> layer?


Something like this.

Thanks


>
> Thanks,
> Yongji
>

\
 
 \ /
  Last update: 2021-06-25 05:10    [W:0.207 / U:0.040 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site