Re: Re: [PATCH v8 09/10] vduse: Introduce VDUSE - vDPA Device in Userspace

On Wed, Jun 23, 2021 at 11:31 AM Jason Wang [off-list ref] wrote:

在 2021/6/22 下午4:14, Yongji Xie 写道:

quoted

On Tue, Jun 22, 2021 at 3:50 PM Jason Wang [off-list ref] wrote:

quoted

在 2021/6/22 下午3:22, Yongji Xie 写道:

quoted

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We need fix a way to propagate the error to the userspace.

E.g if we want to stop the deivce, we will delay the status reset until
we get respose from the userspace?

I didn't get how to delay the status reset. And should it be a DoS
that we want to fix if the userspace doesn't give a response forever?

You're right. So let's make set_status() can fail first, then propagate
its failure via VHOST_VDPA_SET_STATUS.

OK. So we only need to propagate the failure in the vhost-vdpa case, right?

I think not, we need to deal with the reset for virtio as well:

E.g in register_virtio_devices(), we have:

         /* We always start by resetting the device, in case a previous
          * driver messed it up.  This also tests that code path a
little. */
       dev->config->reset(dev);

We probably need to make reset can fail and then fail the
register_virtio_device() as well.

OK, looks like virtio_add_status() and virtio_device_ready()[1] should
be also modified if we need to propagate the failure in the
virtio-vdpa case. Or do we only need to care about the reset case?

[1] https://lore.kernel.org/lkml/20210517093428.670-1-xieyongji@bytedance.com/ (local)

Thanks,
Yongji