Re: [PATCH v6 2/2] xen/domain: adjust domain ID allocation for Arm

[Jan Beulich <jbeulich@suse.com>]

On 16.05.2025 04:04, dmkhn@proton.me wrote:
> --- a/xen/common/domain.c
> +++ b/xen/common/domain.c
> @@ -85,7 +85,7 @@ void __init domid_init(void)
>   *
>   * If hint is outside of valid [0..DOMID_FIRST_RESERVED - 1] range of IDs,
>   * perform an exhaustive search starting from the end of the used domain ID
> - * range.
> + * range, excluding get_initial_domain_id() ID.
>   */
>  domid_t domid_alloc(domid_t domid)
>  {
> @@ -103,6 +103,9 @@ domid_t domid_alloc(domid_t domid)
>              if ( domid == DOMID_FIRST_RESERVED )
>                  domid = 0;
>  
> +            if ( domid == get_initial_domain_id() )
> +                continue;
> +
>              if ( !rangeset_contains_singleton(domid_rangeset, domid) )
>                  break;
>          }

Isn't there a (perhaps even pre-existing) issue here with a DomU potentially
getting ID 0 assigned when get_initial_domain_id() returns non-zero?

Jan