Re: [PATCH 1/2] x86/domctl: Introduce XEN_DOMCTL_SENDTRIGGER_DEBUG

On 20.07.2026 11:25, Tu Dinh wrote:
> VIRQ_DEBUG causes guests to print their diagnostic information.
> Currently, the only way to send VIRQ_DEBUG to a domain is via the 'q'
> debug key. This method indiscriminately sends VIRQ_DEBUG to all domains
> and vcpus.
> 
> When debugging guests, it's useful to have a way to target a specific
> domain with VIRQ_DEBUG. Add XEN_DOMCTL_SENDTRIGGER_DEBUG for this
> purpose.
> 
> Signed-off-by: Tu Dinh <[email protected]>

Fine in principle, but ...

> --- a/xen/arch/x86/domctl.c
> +++ b/xen/arch/x86/domctl.c
> @@ -605,6 +605,11 @@ long arch_do_domctl(
>              }
>              break;
>  
> +        case XEN_DOMCTL_SENDTRIGGER_DEBUG:
> +            ret = 0;
> +            send_guest_vcpu_virq(v, VIRQ_DEBUG);
> +            break;

... unlike the other XEN_DOMCTL_SENDTRIGGER_* this one isn't really x86-specific.
Hence, at the risk of being called guilty in causing scope creep, I think this
wants some re-structuring. The handling of XEN_DOMCTL_sendtrigger wants to move
to common code (at that occasion also making it properly use domain_vcpu()), with
a new arch-specific handler to deal with non-generic XEN_DOMCTL_SENDTRIGGER_*.

And then, if already moving this, it will also want considering where to move it
in do_domctl(): It doesn't look as if holding the domctl lock would be required
here.

Jan