Re: [Xen-devel] [PATCH 03/14] xen/x86: Make mfn_to_gfn typesafe

[Julien Grall <julien.grall@xxxxxxx>]

On 10/05/2019 12:35, Jan Beulich wrote:
> > > > On 07.05.19 at 17:14, <julien.grall@xxxxxxx> wrote:
> > --- a/xen/arch/x86/mm/shadow/common.c
> > +++ b/xen/arch/x86/mm/shadow/common.c
> > @@ -474,7 +474,8 @@ static inline void trace_resync(int event, mfn_t gmfn)
> >       if ( tb_init_done )
> >       {
> >           /* Convert gmfn to gfn */
> > -        unsigned long gfn = mfn_to_gfn(current->domain, gmfn);
> > +        unsigned long gfn = gfn_x(mfn_to_gfn(current->domain, gmfn));
> > +
> >           __trace_var(event, 0/*!tsc*/, sizeof(gfn), &gfn);
> >       }
> Can't you use gfn_t here, and hence avoid the gfn_x()? Same again further
> down.
Because __trace_var will export the value to the guest. I wasn't sure whether we 
can safely consider that gfn_t is exactly the same as unsigned long in debug-build.
Cheers,

--
Julien Grall

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