From mboxrd@z Thu Jan  1 00:00:00 1970
From: Julien Grall <julien.grall@linaro.org>
Subject: Re: [PATCH v3 20/24] xen/passthrough: Extend
 XEN_DOMCTL_assign_device to support DT device
Date: Wed, 11 Mar 2015 13:50:17 +0000
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To: Ian Campbell <ian.campbell@citrix.com>
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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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