From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ian Campbell <ian.campbell@citrix.com>
Subject: Re: [PATCH v3 20/24] xen/passthrough: Extend
 XEN_DOMCTL_assign_device to support DT device
Date: Wed, 11 Mar 2015 13:55:54 +0000
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To: Julien Grall <julien.grall@linaro.org>
Cc: Wei Liu <wei.liu2@citrix.com>, Ian Jackson <ian.jackson@eu.citrix.com>, tim@xen.org, stefano.stabellini@citrix.com, Jan Beulich <jbeulich@suse.com>, xen-devel@lists.xenproject.org, Daniel De Graaf <dgdegra@tycho.nsa.gov>
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On Wed, 2015-03-11 at 13:50 +0000, Julien Grall wrote:
> 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:

That's one option I'd be happy with, yes. Jan might disagree.

> 
> 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,
>