Re: [Xen-devel] [RFC v1 06/15] vt-d: Extend struct iremap_entry to support VT-d Posted-Interrupts

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> Sent: Friday, March 27, 2015 5:58 PM
> 
> >>> On 27.03.15 at 02:53, <feng.wu@xxxxxxxxx> wrote:
> >> From: Andrew Cooper [mailto:andrew.cooper3@xxxxxxxxxx]
> >> Sent: Friday, March 27, 2015 3:01 AM
> >> On 25/03/15 12:31, Feng Wu wrote:
> >> > --- a/xen/drivers/passthrough/vtd/iommu.h
> >> > +++ b/xen/drivers/passthrough/vtd/iommu.h
> >> > @@ -303,6 +303,18 @@ struct iremap_entry {
> >> >               res_2   : 8,
> >> >               dst     : 32;
> >> >       }lo;
> >> > +    struct {
> >> > +        u64 p       : 1,
> >> > +            fpd     : 1,
> >> > +            res_1   : 6,
> >> > +            avail   : 4,
> >> > +            res_2   : 2,
> >> > +            urg     : 1,
> >> > +            im      : 1,
> >> > +            vector  : 8,
> >> > +            res_3   : 14,
> >> > +            pda_l   : 26;
> >> > +    }lo_intpost;
> >> >     };
> >> >     union {
> >> >       u64 hi_val;
> >> > @@ -312,6 +324,13 @@ struct iremap_entry {
> >> >               svt     : 2,
> >> >               res_1   : 44;
> >> >       }hi;
> >> > +    struct {
> >> > +        u64 sid     : 16,
> >> > +            sq      : 2,
> >> > +            svt     : 2,
> >> > +            res_1   : 12,
> >> > +            pda_h   : 32;
> >> > +    }hi_intpost;
> >>
> >> I would prefer if this union was reformatted as I suggested in the
> >> thread from your design doc, but I won't insist on it as a blocker to 
> >> entry.
> >
> > Thanks for the comments. I also considered your sugguestion on the Design
> > doc, here is your proposal:
> >
> > struct iremap_entry {
> >     union {
> >         struct { u64 lo, hi; };
> >         struct { <bitfields> } norm; (names subject to improvement)
> >         struct { <bitfields> } post;
> >     };
> > };
> >
> > Seems in that way, we need to change some existing code to adapt to
> > this new structure. I am okay with both of them, but can we listen
> > some voices form some others? Is it okay for you?
> 
> I think this would be a good move, but in the end it's the VT-d
> maintainers who got to decide.
> 

yes it's a good move. 

Thanks
Kevin

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