Re: [PATCH] vhost: introduce mdev based hardware backend

Tiwei Bie
2019-09-27T08:07:05Z

On Fri, Sep 27, 2019 at 03:14:42PM +0800, Jason Wang wrote:
> On 2019/9/27 下午12:54, Tiwei Bie wrote:
> > > > +
> > > > + /*
> > > > + * In vhost-mdev, userspace should pass ring addresses
> > > > + * in guest physical addresses when IOMMU is disabled or
> > > > + * IOVAs when IOMMU is enabled.
> > > > + */
> > > A question here, consider we're using noiommu mode. If guest physical
> > > address is passed here, how can a device use that?
> > >
> > > I believe you meant "host physical address" here? And it also have the
> > > implication that the HPA should be continuous (e.g using hugetlbfs).
> > The comment is talking about the virtual IOMMU (i.e. iotlb in vhost).
> > It should be rephrased to cover the noiommu case as well. Thanks for
> > spotting this.
>
>
> So the question still, if GPA is passed how can it be used by the
> virtio-mdev device?

Sorry if I didn't make it clear..
Of course, GPA can't be passed in noiommu mode.

>
> Thanks
>