Messages in this thread | | | Subject | Re: [PATCH v8 09/10] vduse: Introduce VDUSE - vDPA Device in Userspace | From | Jason Wang <> | Date | Fri, 25 Jun 2021 11:08:42 +0800 |
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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 >
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