Re: [Qemu-devel] [PATCH 2/2 V7] qemu,qmp: add inject-nmi qmp command

[Luiz Capitulino]

On Mon, 04 Apr 2011 14:19:58 +0200
Markus Armbruster <address@hidden> wrote:

> [Note cc: Anthony]
> 
> "Daniel P. Berrange" <address@hidden> writes:
> 
> > On Mon, Mar 07, 2011 at 05:46:28PM +0800, Lai Jiangshan wrote:
> >> From: Lai Jiangshan <address@hidden>
> >> Date: Mon, 7 Mar 2011 17:05:15 +0800
> >> Subject: [PATCH 2/2] qemu,qmp: add inject-nmi qmp command
> >> 
> >> inject-nmi command injects an NMI on all CPUs of guest.
> >> It is only supported for x86 guest currently, it will
> >> returns "Unsupported" error for non-x86 guest.
> >> 
> >> ---
> >>  hmp-commands.hx |    2 +-
> >>  monitor.c       |   18 +++++++++++++++++-
> >>  qmp-commands.hx |   29 +++++++++++++++++++++++++++++
> >>  3 files changed, 47 insertions(+), 2 deletions(-)
> >
> > Does anyone have any feedback on this addition, or are all new
> > QMP patch proposals blocked pending Anthony's QAPI work ?

No, we agreed on merging stuff against current QMP.

> That would be bad.  Anthony, what's holding this back?

I remember Anthony asked for errors descriptions.

> 
> > We'd like to support it in libvirt and thus want it to be
> > available in QMP, as well as HMP.
> >
> >> @@ -2566,6 +2566,22 @@ static void do_inject_nmi(Monitor *mon, const QDict 
> >> *qdict)
> >>              break;
> >>          }
> >>  }
> >> +
> >> +static int do_inject_nmi(Monitor *mon, const QDict *qdict, QObject 
> >> **ret_data)
> >> +{
> >> +    CPUState *env;
> >> +
> >> +    for (env = first_cpu; env != NULL; env = env->next_cpu)
> >> +        cpu_interrupt(env, CPU_INTERRUPT_NMI);
> >> +
> >> +    return 0;
> >> +}
> >> +#else
> >> +static int do_inject_nmi(Monitor *mon, const QDict *qdict, QObject 
> >> **ret_data)
> >> +{
> >> +    qerror_report(QERR_UNSUPPORTED);
> >> +    return -1;
> >> +}
> >>  #endif
> >>  
> >
> > Interesting that with HMP you need to specify a single CPU index, but
> > with QMP it is injecting to all CPUs at once. Is there any compelling
> > reason why we'd ever need the ability to only inject to a single CPU
> > from an app developer POV ?
> 
> Quoting my own executive summary on this issue:
> 
> * Real hardware's NMI button injects all CPUs.  This is the primary use
>   case.
> 
> * Lai said injecting a single CPU can be useful for debugging.  Was
>   deemed acceptable as secondary use case.
> 
>   Lai also pointed out that the human monitor's nmi command injects a
>   single CPU.  That was dismissed as irrelevant for QMP.
> 
> * No other use cases have been presented.
>