Re: [PATCH v2 2/2] domain: expose newly introduced hypercalls as XENFEAT

["Roger Pau Monné" <roger.pau@citrix.com>]

On Fri, Oct 06, 2023 at 02:05:18PM +0100, Andrew Cooper wrote:
> On 06/10/2023 2:00 pm, Roger Pau Monne wrote:
> > diff --git a/xen/include/public/features.h b/xen/include/public/features.h
> > index d2a9175aae67..22713a51b520 100644
> > --- a/xen/include/public/features.h
> > +++ b/xen/include/public/features.h
> > @@ -111,6 +111,15 @@
> >  #define XENFEAT_not_direct_mapped         16
> >  #define XENFEAT_direct_mapped             17
> >  
> > +/*
> > + * Signal whether the domain is permitted to use the following hypercalls:
> > + *
> > + * VCPUOP_register_runstate_phys_area
> > + * VCPUOP_register_vcpu_time_phys_area
> > + */
> > +#define XENFEAT_runstate_phys_area	  18
> > +#define XENFEAT_vcpu_time_phys_area	  19
> > +
> >  #define XENFEAT_NR_SUBMAPS 1
> >  
> >  #endif /* __XEN_PUBLIC_FEATURES_H__ */
> > diff --git a/xen/include/public/vcpu.h b/xen/include/public/vcpu.h
> > index 8fb0bd1b6c03..03b031a3e557 100644
> > --- a/xen/include/public/vcpu.h
> > +++ b/xen/include/public/vcpu.h
> > @@ -236,6 +236,9 @@ DEFINE_XEN_GUEST_HANDLE(vcpu_register_time_memory_area_t);
> >   * Note that the area registered via VCPUOP_register_runstate_memory_area will
> >   * be updated in the same manner as the one registered via virtual address PLUS
> >   * VMASST_TYPE_runstate_update_flag engaged by the domain.
> > + *
> > + * XENFEAT_{runstate,vcpu_time}_phys_area feature bits signal if the domain is
> > + * permitted the usage of the hypercalls.
> >   */
> >  #define VCPUOP_register_runstate_phys_area      14
> >  #define VCPUOP_register_vcpu_time_phys_area     15
> 
> For both of these, I'd suggest s/permitted/able/.  For older versions of
> Xen which don't advertise the XENFEAT, it's a matter of capability, not
> permission.
> 
> Otherwise, Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com> and
> I'm happy to adjust on commit to save sending out a v3.

TBH I've used permitted because that's the wording you used in your
reply to v1, I'm perfectly fine with switching to able.

https://lore.kernel.org/xen-devel/ac4842a9-7f62-4c64-9a3a-2ec2b1e97699@citrix.com/

Thanks, Roger.