Re: [RFC 4/6] capabilities: introduce console io as a domain capability

["Daniel P. Smith" <dpsmith@xxxxxxxxxxxxxxxxxxxx>]

On 8/8/23 11:24, Jan Beulich wrote:
> On 01.08.2023 22:20, Daniel P. Smith wrote:
> > --- a/xen/include/xen/sched.h
> > +++ b/xen/include/xen/sched.h
> > @@ -472,8 +472,8 @@ struct domain
> >   #define ROLE_HARDWARE_DOMAIN   (1U<<2)
> >   #define ROLE_XENSTORE_DOMAIN   (1U<<3)
> >       uint8_t          role;
> > -    /* Can this guest access the Xen console? */
> > -    bool             is_console;
> > +#define CAP_CONSOLE_IO  (1U<<0)
> > +    uint8_t          capabilities;
> >       /* Is this guest being debugged by dom0? */
> >       bool             debugger_attached;
> >       /*
> > @@ -1146,6 +1146,27 @@ static always_inline bool is_hvm_vcpu(const struct vcpu 
> > *v)
> >       return is_hvm_domain(v->domain);
> >   }
> >   
> > +static always_inline bool domain_has_cap(
> > +    const struct domain *d, uint8_t cap)
> > +{
> > +    return d->capabilities & cap;
> > +}
> What you implement here is effectively domain_has_any_cap(), which I
> don't think is of much use. At the very least you want to assert that
> cap is a power of two. But perhaps you rather want the caller to pass
> in a bit number, not a mask, such that it's obvious that only one
> thing can be checked at a time.
I did this thinking I was going to save keystrokes and encapsulate the 
check, but I just double checked and it would have only saved one. I 
will drop this and put the explicit bit checks at all the check sites.
> > +static always_inline bool domain_set_cap(
> > +    struct domain *d, uint8_t cap)
> > +{
> > +    switch ( cap )
> > +    {
> > +    case CAP_CONSOLE_IO:
> > +        d->capabilities |= cap;
> > +        break;
> > +    default:
> > +        return false;
> > +    }
> > +
> > +    return domain_has_cap(d, cap);
> > +}
> The "set" operation doesn't need to be an inline function, does it?
I guess not, I can move into common/domain.c.

v/r,
dps