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 12:37:14 +0000
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To: Julien Grall <julien.grall@linaro.org>
Cc: Wei Liu <wei.liu2@citrix.com>, tim@xen.org, Ian Jackson <ian.jackson@eu.citrix.com>, 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 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.