Re: [Xen-devel] [PATCH v3 08/13] xen/passthrough: iommu: Basic support of device tree assignment

[Julien Grall <julien.grall@xxxxxxxxxx>]

Hi Ian,

On 19/03/14 10:12, Ian Campbell wrote:
> > On 03/18/2014 04:33 PM, Ian Campbell wrote:
> > > On Tue, 2014-03-11 at 15:49 +0000, Julien Grall wrote:
> > > > Add IOMMU helpers to support device tree assignment/deassignment. This patch
> > > > introduces 2 new fields in the dt_device_node:
> > > >      - is_protected: Does the device is protected by an IOMMU
> > > >      - next_assigned: Pointer to the next device assigned to the same
> > > >      domain
> > > Am I correct that this list is not maintained for dom0? The behaviour of
> > > dt_assign_device and dt_deassign_device seems to rely on it?
> > DOM0 will call dt_assign_device for every device protected by the IOMMU
> > (see patch #9). So it will itself have a list maintained.
> Does this not mean that iommu_assign_dt_device will refuse to assign the
> device to another domain (next_assigned list is not empty).
Yes. After thinking, I'm not sure we want maintain a list for dom0.
At least the iommu_deassign_dt_device function is wrong because the 
device is not reassigned to dom0 (from the list point of view).

> BTW, next_assigned is not a very good name for this list, since the
> "nextness" is abstracted away. Consider just device_list.
I found device_list too generic. We don't know if it's the list of all 
the devices or just the ones of a specific domain.
What about domain_device_list?

Regards,

--
Julien Grall

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