RE: [PATCH v3 15/28] xen/domctl: wrap domain_kill() with CONFIG_MGMT_HYPERCALLS

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

[Public]

> -----Original Message-----
> From: Jan Beulich <jbeulich@xxxxxxxx>
> Sent: Wednesday, November 12, 2025 6:02 PM
> To: Penny, Zheng <penny.zheng@xxxxxxx>
> Cc: Huang, Ray <Ray.Huang@xxxxxxx>; oleksii.kurochko@xxxxxxxxx; Stefano
> Stabellini <sstabellini@xxxxxxxxxx>; Julien Grall <julien@xxxxxxx>; Bertrand
> Marquis <bertrand.marquis@xxxxxxx>; Orzel, Michal <Michal.Orzel@xxxxxxx>;
> Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>; Andrew Cooper
> <andrew.cooper3@xxxxxxxxxx>; Anthony PERARD <anthony.perard@xxxxxxxxxx>;
> Roger Pau Monné <roger.pau@xxxxxxxxxx>; Shawn Anastasio
> <sanastasio@xxxxxxxxxxxxxxxxxxxxx>; Alistair Francis 
> <alistair.francis@xxxxxxx>;
> Bob Eshleman <bobbyeshleman@xxxxxxxxx>; Connor Davis
> <connojdavis@xxxxxxxxx>; Tamas K Lengyel <tamas@xxxxxxxxxxxxx>; xen-
> devel@xxxxxxxxxxxxxxxxxxxx
> Subject: Re: [PATCH v3 15/28] xen/domctl: wrap domain_kill() with
> CONFIG_MGMT_HYPERCALLS
>
> On 12.11.2025 09:58, Penny, Zheng wrote:
> > [Public]
> >
> >> -----Original Message-----
> >> From: Jan Beulich <jbeulich@xxxxxxxx>
> >> Sent: Thursday, October 30, 2025 8:44 PM
> >> To: Penny, Zheng <penny.zheng@xxxxxxx>
> >> Cc: Huang, Ray <Ray.Huang@xxxxxxx>; oleksii.kurochko@xxxxxxxxx;
> >> Stefano Stabellini <sstabellini@xxxxxxxxxx>; Julien Grall
> >> <julien@xxxxxxx>; Bertrand Marquis <bertrand.marquis@xxxxxxx>; Orzel,
> >> Michal <Michal.Orzel@xxxxxxx>; Volodymyr Babchuk
> >> <Volodymyr_Babchuk@xxxxxxxx>; Andrew Cooper
> >> <andrew.cooper3@xxxxxxxxxx>; Anthony PERARD
> >> <anthony.perard@xxxxxxxxxx>; Roger Pau Monné <roger.pau@xxxxxxxxxx>;
> >> Shawn Anastasio <sanastasio@xxxxxxxxxxxxxxxxxxxxx>; Alistair Francis
> >> <alistair.francis@xxxxxxx>; Bob Eshleman <bobbyeshleman@xxxxxxxxx>;
> >> Connor Davis <connojdavis@xxxxxxxxx>; Tamas K Lengyel
> >> <tamas@xxxxxxxxxxxxx>; xen- devel@xxxxxxxxxxxxxxxxxxxx
> >> Subject: Re: [PATCH v3 15/28] xen/domctl: wrap domain_kill() with
> >> CONFIG_MGMT_HYPERCALLS
> >>
> >> On 13.10.2025 12:15, Penny Zheng wrote:
> >>> --- a/xen/arch/x86/mm/mem_sharing.c
> >>> +++ b/xen/arch/x86/mm/mem_sharing.c
> >>> @@ -1396,6 +1396,7 @@ int __mem_sharing_unshare_page(struct domain
> *d,
> >>>      return rc;
> >>>  }
> >>>
> >>> +#ifdef CONFIG_MGMT_HYPERCALLS
> >>>  int relinquish_shared_pages(struct domain *d)  {
> >>>      int rc = 0;
> >>> @@ -1452,6 +1453,7 @@ int relinquish_shared_pages(struct domain *d)
> >>>      p2m_unlock(p2m);
> >>>      return rc;
> >>>  }
> >>> +#endif /* CONFIG_MGMT_HYPERCALLS */
> >>>
> >>>  static int range_share(struct domain *d, struct domain *cd,
> >>>                         struct mem_sharing_op_range *range)
> >>
> >> Is this necessary? Shouldn't MEM_SHARING as a whole become dependent
> >> upon MGMT_HYPERCALLS, then also covering XENMEM_sharing_op? (The
> same
> >> will already implicitly happen for MEM_PAGING, due to its VM_EVENT
> >> dependency.)
> >>
> >
> > Yes, Since I didn't see VM_EVENT dependency for MEM_SHARING. I'm not
> 100% sure that whether memory sharing feature is dependent on VM_EVENT. Also
> as I roughly look through the codes in mm/mem_sharing.c, maybe only
> mem_sharing_notify_enomem() utilizes vm event subsystem.
>
> Right, a little while ago (iirc in the context of your work) Tamas said the 
> same.
> But I didn't ask about VM_EVENT; I asked about MGMT_HYPERCALLS.
>

Oh, sorry....
Yes, The enabling bit (d->arch.hvm.mem_sharing.enabled) could only be enabled 
via domctl-op. I will make it depend on MGMT_HYPERCALLS.

> Jan