Re: [RFC PATCH v3 08/18] xen/arm: vITS: Add virtual ITS driver

[Ian Campbell <ian.campbell@citrix.com>]

On Thu, 2015-07-02 at 19:03 +0530, Vijay Kilari wrote:
> Hi Julien,
> 
> On Tue, Jun 23, 2015 at 10:09 PM, Julien Grall <julien.grall@citrix.com> wrote:
> > Hi Vijay,
> >
> >>
> >> +struct vits_device {
> >> +    uint32_t vdevid;
> >> +    uint32_t pdevid;
> >> +    struct its_device *its_dev;
> >> +    struct rb_node node;
> >> +};
> >
> > We spoke about a specific structure in the design [2] but you introduced
> > a new one. Why?
> 
> Section 6 of DraftG specifies to manage separate tree for device assignment.
> This helps to manage RB-tree per domain to hold list of devices
> assigned to this domain index with vdevid.
> 
> This helps to check if device is assigned to this domain before processing
> any ITS command with that vdevid.
> 
> >
> > Having everything in the its_device would help to catch a device
> > attached to 2 different domains...
> 
> One option is to introduce a new variable inside its_device to know
> to which domain the device is currently assigned.

IIRC that's what I intended, e.g. two trees referencing the same
underlying data structure. Sorry that wasn't clear.

> 
> >
> > Also, the field pdevid is not vits specific but its.
> pdevid can be removed as its_device structure already has it
> 
> Regards
> Vijay