Re: [Xen-devel] [PATCH 5/8] viridian: use viridian_map/unmap_guest_page() for reference tsc page

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Xen-devel [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxxx] On Behalf
> Of Paul Durrant
> Sent: 03 January 2019 09:20
> To: Wei Liu <wei.liu2@xxxxxxxxxx>
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx; Roger Pau Monne
> <roger.pau@xxxxxxxxxx>; Wei Liu <wei.liu2@xxxxxxxxxx>; Jan Beulich
> <jbeulich@xxxxxxxx>; Andrew Cooper <Andrew.Cooper3@xxxxxxxxxx>
> Subject: Re: [Xen-devel] [PATCH 5/8] viridian: use
> viridian_map/unmap_guest_page() for reference tsc page
> 
> > -----Original Message-----
> > From: Wei Liu [mailto:wei.liu2@xxxxxxxxxx]
> > Sent: 02 January 2019 15:55
> > To: Paul Durrant <Paul.Durrant@xxxxxxxxxx>
> > Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx; Jan Beulich <jbeulich@xxxxxxxx>;
> > Andrew Cooper <Andrew.Cooper3@xxxxxxxxxx>; Wei Liu
> <wei.liu2@xxxxxxxxxx>;
> > Roger Pau Monne <roger.pau@xxxxxxxxxx>
> > Subject: Re: [PATCH 5/8] viridian: use viridian_map/unmap_guest_page()
> for
> > reference tsc page
> >
> > On Thu, Dec 20, 2018 at 04:33:42PM +0000, Paul Durrant wrote:
> > > Whilst the reference tsc page does not currently need to be kept
> mapped
> > > after it is initially set up (or updated after migrate), the code can
> > > be simplified by using the common guest page map/unmap and dump
> > functions.
> > > New functionality added by a subsequent patch will also require the
> page
> > to
> > > kept mapped for the lifetime of the domain.
> > >
> > > NOTE: Because the reference tsc page is per-domain rather than per-
> vcpu
> > >       this patch also changes viridian_map_guest_page() to take a
> domain
> > >       pointer rather than a vcpu pointer.
> > >
> > > Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
> > > ---
> > > Cc: Jan Beulich <jbeulich@xxxxxxxx>
> > > Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> > > Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
> > > Cc: "Roger Pau Monné" <roger.pau@xxxxxxxxxx>
> > > ---
> > >  xen/arch/x86/hvm/viridian/private.h  |  2 +-
> > >  xen/arch/x86/hvm/viridian/synic.c    |  8 +++-
> > >  xen/arch/x86/hvm/viridian/time.c     | 57 ++++++++++-----------------
> -
> > >  xen/arch/x86/hvm/viridian/viridian.c |  3 +-
> > >  xen/include/asm-x86/hvm/viridian.h   |  2 +-
> > >  5 files changed, 28 insertions(+), 44 deletions(-)
> > >
> > > diff --git a/xen/arch/x86/hvm/viridian/private.h
> > b/xen/arch/x86/hvm/viridian/private.h
> > > index 1864bab3d5..0bf34eefe0 100644
> > > --- a/xen/arch/x86/hvm/viridian/private.h
> > > +++ b/xen/arch/x86/hvm/viridian/private.h
> > > @@ -111,7 +111,7 @@ void viridian_time_load_domain_ctxt(
> > >
> > >  void viridian_dump_guest_page(const struct vcpu *v, const char *name,
> > >                                const struct viridian_page *vp);
> > > -void viridian_map_guest_page(struct vcpu *v, struct viridian_page
> *vp);
> > > +void viridian_map_guest_page(struct domain *d, struct viridian_page
> > *vp);
> >
> > Since you modify this anyway, can you constify struct domain?
> >
> 
> Yes, I guess that should be do-able now that the viridian_page is in a
> separate allocation unit.

Alas, no. The call to get_page_from_gfn() takes a non-const struct domain 
pointer, and I'm not opening that can of worms. Does your R-b still stand?

  Paul

> 
> > With that:
> >
> > Reviewed-by: Wei Liu <wei.liu2@xxxxxxxxxx>
> 
> Thanks,
> 
>   Paul
> 
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