On Sat, Aug 12, 2023 at 03:25:10PM +0900, Akihiko Odaki wrote:
> > > By the way, crosvm's logic to detach endpoint on removal looks incorrect
> > > for
> > > me. A domain may have several endpoints attached, but the code looks like
> > > it's always destroying a domain whether there are other endpoints attached
> > > to the domain. I'm adding Zide Chen, who wrote the code according to git
> > > blame, and [email protected] to CC.
> >
> > Link to this thread for more context:
> > https://lore.kernel.org/virtio-dev/[email protected]/
> >
> > I thought crosvm rejected attaching multiple endpoints to one domain but I
> > think I misread. Rejecting multiple attach would be a straightforward fix
> > (it's allowed by the spec), though it would prevent assigning endpoints
> > that cannot be isolated from each others by the hardware (the driver won't
> > attach those to different domains, if it's made aware that they should be
> > in the same IOMMU group, for example if they are on a conventional PCI
> > bus).
>
> Now we figured out an endpoint should not be detached from a domain without
> a request from the driver anyway so the code to detach an endpoint can be
> simply removed.
Yes, but I think the other detach path, when handling ATTACH or DETACH
requests, doesn't support domains with multiple endpoints attached either:
// Currently, we only support detaching an endpoint if it is the only
endpoint attached
// to its domain.
But the ATTACH handler seems to accept attaching multiple endpoints to the
same domain?
Thanks,
Jean
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