Re: [PATCH 3/4] domctl: Provide appropriate error code when VM events are not supported

[Jan Beulich <jbeulich@xxxxxxxx>]

On 05.12.2025 21:36, Milan Djokic wrote:
> Return -EOPNOTSUPP when XEN_DOMCTL_set_access_required command is invoked
> while VM events and monitoring support is disabled.

This is more bounded than the pretty wide subject. Taking the subject and
considering there are other VM_EVENT related domctl-s, is this one really
the only one in need of adjustment?

> --- a/xen/common/domctl.c
> +++ b/xen/common/domctl.c
> @@ -787,19 +787,22 @@ long do_domctl(XEN_GUEST_HANDLE_PARAM(xen_domctl_t) 
> u_domctl)
>              copyback = true;
>          break;
>  
> -#ifdef CONFIG_VM_EVENT
>      case XEN_DOMCTL_set_access_required:
> -        if ( unlikely(current->domain == d) ) /* no domain_pause() */
> -            ret = -EPERM;
> +        if ( !IS_ENABLED(CONFIG_VM_EVENT) )
> +            ret = -EOPNOTSUPP;
>          else

If you convert this to

        else if ( unlikely(current->domain == d) ) /* no domain_pause() */

then ...

>          {
> -            domain_pause(d);
> -            arch_p2m_set_access_required(d,
> -                op->u.access_required.access_required);
> -            domain_unpause(d);
> +            if ( unlikely(current->domain == d) ) /* no domain_pause() */
> +                ret = -EPERM;
> +            else
> +            {
> +                domain_pause(d);
> +                arch_p2m_set_access_required(d,
> +                    op->u.access_required.access_required);
> +                domain_unpause(d);
> +            }

... the need for re-indenting disappears, and we get away with less churn.

Jan