Re: [Xen-devel] [PATCH v3 20/24] xen/passthrough: Extend XEN_DOMCTL_assign_device to support DT device

[Julien Grall <julien.grall@xxxxxxxxxx>]

Hi Ian,

On 11/03/2015 12:37, Ian Campbell wrote:
> On Tue, 2015-03-10 at 16:33 +0000, Julien Grall wrote:
> > Hi Ian,
> >
> > On 20/02/15 17:17, Ian Campbell wrote:
> > > > +    /* TODO: Do we need to check is_dying? Mostly to protect against
> > > > +     * hypercall trying to passthrough a device while we are
> > > > +     * dying.
> > > FWIW the PCI case appears not to care...
> > There is one place in XEN_DOMCTL_assign_device...
> >
> > Although I don't understand much the usage of is_dying.
> >
> > > > +     */
> > > > +
> > > > +    switch ( domctl->cmd )
> > > > +    {
> > > > +    case XEN_DOMCTL_assign_device:
> > > > +        ret = -ENOSYS;
> > > > +        if ( domctl->u.assign_device.dev != XEN_DOMCTL_DEV_DT )
> > > > +            break;
> > > You added something similar to iommu_do_pci_domctl, would it not be
> > > preferable for the caller to switch on domctl->u.assign_device.dev and
> > > call the correct iommu_do_*_domctl?
> > I though about it. It would require to stub iommu_do_*_domctl. So I
> > preferred to chose the current solution.
> You mean iommu_do_{pci,dt}_domctl?
>
> IIRC you already added suitable #defines for when these features are
> present, so reusing them at the call sites wouldn't be too bad, or else
> stubs aren't the worst thing either.
Hmmm I think I got you point now. Do you mean have something like:

switch (domctl->u.assign_device.dev)
{
#ifdef HAS_PCI
case XEN_DOMCTL_DEV_PCI:
    ret = iommu_do_pci_domctl();
    break;
#endif
#ifdef HAS_DEVICE_TREE
case XEN_DOMCTL_DEV_DT:
    ret = iommu_do_dt_domctl()
    break;
#endif

default:
   ret = -ENOSYS;
}

Regards,

--
Julien Grall

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