Re: [PATCH v2 10/13] x86/mpx: Map/unmap xsave area in in read_bndcfgu()

["Alejandro Vallejo" <alejandro.vallejo@cloud.com>]

On Mon Dec 9, 2024 at 4:30 PM GMT, Jan Beulich wrote:
> On 05.11.2024 15:33, Alejandro Vallejo wrote:
> > --- a/xen/arch/x86/xstate.c
> > +++ b/xen/arch/x86/xstate.c
> > @@ -1022,9 +1022,10 @@ int handle_xsetbv(u32 index, u64 new_bv)
> >  
> >  uint64_t read_bndcfgu(void)
> >  {
> > +    uint64_t bndcfgu = 0;
> >      unsigned long cr0 = read_cr0();
> > -    struct xsave_struct *xstate
> > -        = idle_vcpu[smp_processor_id()]->arch.xsave_area;
> > +    struct vcpu *v = idle_vcpu[smp_processor_id()];
>
> Can this be pointer-to-const? Certainly right now, so the question is rather
> meant to be forward looking.
>
> > +    struct xsave_struct *xstate = VCPU_MAP_XSAVE_AREA(v);
>
> This certainly can be pointer-to-const, just like ...
>
> >      const struct xstate_bndcsr *bndcsr;
>
> ... this is.
>
> Jan

Yes, those retained non-const because of the now missing patch to zero-out
bndcfgu.

Cheers,
Alejandro