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

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

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?


Julien Grall

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