RE: [PATCH v2 18/26] xen/domctl: wrap xsm_getdomaininfo() with CONFIG_MGMT_HYPERCALLS

["Penny, Zheng" <penny.zheng@xxxxxxx>]

[Public]

> -----Original Message-----
> From: Jan Beulich <jbeulich@xxxxxxxx>
> Sent: Thursday, September 11, 2025 9:30 PM
> To: Penny, Zheng <penny.zheng@xxxxxxx>
> Cc: Huang, Ray <Ray.Huang@xxxxxxx>; Daniel P. Smith
> <dpsmith@xxxxxxxxxxxxxxxxxxxx>; xen-devel@xxxxxxxxxxxxxxxxxxxx
> Subject: Re: [PATCH v2 18/26] xen/domctl: wrap xsm_getdomaininfo() with
> CONFIG_MGMT_HYPERCALLS
>
> On 10.09.2025 09:38, Penny Zheng wrote:
> > --- a/xen/include/xsm/xsm.h
> > +++ b/xen/include/xsm/xsm.h
> > @@ -55,8 +55,8 @@ struct xsm_ops {
> >      void (*security_domaininfo)(struct domain *d,
> >                                  struct xen_domctl_getdomaininfo *info);
> >      int (*domain_create)(struct domain *d, uint32_t ssidref);
> > -    int (*getdomaininfo)(struct domain *d);
> >  #ifdef CONFIG_MGMT_HYPERCALLS
> > +    int (*getdomaininfo)(struct domain *d);
> >      int (*domctl_scheduler_op)(struct domain *d, int op);
> >      int (*sysctl_scheduler_op)(int op);
> >      int (*set_target)(struct domain *d, struct domain *e); @@ -234,7
> > +234,11 @@ static inline int xsm_domain_create(
> >
> >  static inline int xsm_getdomaininfo(xsm_default_t def, struct domain
> > *d)  {
> > +#ifdef CONFIG_MGMT_HYPERCALLS
> >      return alternative_call(xsm_ops.getdomaininfo, d);
> > +#else
> > +    return -EOPNOTSUPP;
> > +#endif
> >  }
>
> This is in use by a Xenstore sysctl and a Xenstore domctl. The sysctl is hence
> already broken with the earlier series. Now the domctl is also being screwed 
> up. I
> don't think MGMT_HYPERCALLS really ought to extend to any operations available
> to other than the core toolstack. That's the Xenstore ones here, but also the 
> ones
> used by qemu (whether run in Dom0 or a stubdom).

Maybe not only limited to the core toolstack. In dom0less/hyperlaunched 
scenarios, hypercalls are strictly limited. QEMU is also limited to pvh machine 
type and with very restricted functionality(, only acting as a few virtio-pci 
devices backend). @Andryuk, Jason @Stabellini, Stefano Am I understanding 
correctly and thoroughly about our scenario here for upstream?
Tracking the codes, if Xenstore is created as a stub domain, it requires 
getdomaininfo-domctl to acquire related info.  Sorry, I haven't found how it 
was called in QEMU...

> IOW I think there's a conceptual issue with this work which needs resolving 
> first.
>
> Jan