Re: [Xen-devel] [PATCH v18 05/11] x86/mm: add HYPERVISOR_memory_op to acquire guest resources

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Xen-devel [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxxx] On Behalf
> Of Jan Beulich
> Sent: 29 March 2018 15:25
> To: Paul Durrant <Paul.Durrant@xxxxxxxxxx>
> Cc: StefanoStabellini <sstabellini@xxxxxxxxxx>; Wei Liu
> <wei.liu2@xxxxxxxxxx>; Andrew Cooper <Andrew.Cooper3@xxxxxxxxxx>; Tim
> (Xen.org) <tim@xxxxxxx>; George Dunlap <George.Dunlap@xxxxxxxxxx>;
> Julien Grall <julien.grall@xxxxxxx>; xen-devel@xxxxxxxxxxxxxxxxxxxx; Ian
> Jackson <Ian.Jackson@xxxxxxxxxx>
> Subject: Re: [Xen-devel] [PATCH v18 05/11] x86/mm: add
> HYPERVISOR_memory_op to acquire guest resources
> 
> >>> On 29.03.18 at 15:17, <Paul.Durrant@xxxxxxxxxx> wrote:
> >>  -----Original Message-----
> >> From: Xen-devel [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxxx] On
> Behalf
> >> Of Paul Durrant
> >> Sent: 29 March 2018 13:43
> >> To: 'Jan Beulich' <JBeulich@xxxxxxxx>
> >> Cc: StefanoStabellini <sstabellini@xxxxxxxxxx>; Wei Liu
> >> <wei.liu2@xxxxxxxxxx>; Andrew Cooper <Andrew.Cooper3@xxxxxxxxxx>;
> Tim
> >> (Xen.org) <tim@xxxxxxx>; George Dunlap <George.Dunlap@xxxxxxxxxx>;
> >> Julien Grall <julien.grall@xxxxxxx>; xen-devel@xxxxxxxxxxxxxxxxxxxx; Ian
> >> Jackson <Ian.Jackson@xxxxxxxxxx>
> >> Subject: Re: [Xen-devel] [PATCH v18 05/11] x86/mm: add
> >> HYPERVISOR_memory_op to acquire guest resources
> >>
> >> > -----Original Message-----
> >> > From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> >> > Sent: 29 March 2018 13:29
> >> > To: Paul Durrant <Paul.Durrant@xxxxxxxxxx>
> >> > Cc: Julien Grall <julien.grall@xxxxxxx>; Andrew Cooper
> >> > <Andrew.Cooper3@xxxxxxxxxx>; George Dunlap
> >> > <George.Dunlap@xxxxxxxxxx>; Ian Jackson <Ian.Jackson@xxxxxxxxxx>;
> Wei
> >> Liu
> >> > <wei.liu2@xxxxxxxxxx>; StefanoStabellini <sstabellini@xxxxxxxxxx>; xen-
> >> > devel@xxxxxxxxxxxxxxxxxxxx; Konrad Rzeszutek Wilk
> >> > <konrad.wilk@xxxxxxxxxx>; Tim (Xen.org) <tim@xxxxxxx>
> >> > Subject: RE: [PATCH v18 05/11] x86/mm: add HYPERVISOR_memory_op
> to
> >> > acquire guest resources
> >> >
> >> > >>> On 29.03.18 at 11:53, <Paul.Durrant@xxxxxxxxxx> wrote:
> >> > >> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> >> > >> Sent: 26 March 2018 12:41
> >> > >>
> >> > >> >>> On 22.03.18 at 12:55, <paul.durrant@xxxxxxxxxx> wrote:
> >> > >> > --- a/xen/include/xlat.lst
> >> > >> > +++ b/xen/include/xlat.lst
> >> > >> > @@ -86,6 +86,7 @@
> >> > >> >  !  memory_map                      memory.h
> >> > >> >  !  memory_reservation              memory.h
> >> > >> >  !  mem_access_op                   memory.h
> >> > >> > +!  mem_acquire_resource            memory.h
> >> > >>
> >> > >> Why ! ? The layout doesn't appear to differ between native and
> >> > >> compat. Or wait, the handle does, but why is that not
> >> > >> XEN_GUEST_HANDLE_64()? (I've skipped the compat layer code
> >> > >> in this round of review for that reason.)
> >> > >
> >> > > It's been XEN_GUEST_HANDLE throughout all but the earliest
> revisions of
> >> > the
> >> > > patch and I have not modified the compat code massively since you
> gave
> >> > your
> >> > > R-b anyway... the only thing that changed was copying back the new
> flags
> >> > > value.
> >> >
> >> > Granted I could/should have noticed this earlier, but being able to
> >> > get away without compat translation would certainly be a win, and
> >> > we have that option since this is a tools-only interface.
> >> >
> >>
> >> Ok. I'll see if I can get this done today then.
> >>
> >>   Paul
> >
> > Actually, I'm getting confused by all this... The handle is for an array of
> > xen_pfn_t, which means they are going to be 32-bits wide for a 32-bit tools
> > domain. Doesn't this mean I'm going to need compat code to iterate and
> > translate the array anyway?
> 
> Oh, yes, indeed. I'm sorry for the confusion. With the other remarks
> addressed feel free to add
> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

Ok, thanks :-)

  Paul

> 
> Jan
> 
> 
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