Re: [Qemu-devel] [PATCH v3 1/4] cpus: Define NMI callback

[Cornelia Huck <cornelia.huck@de.ibm.com>]

On Tue, 10 Jun 2014 09:39:51 -0400
Luiz Capitulino <lcapitulino@redhat.com> wrote:

> On Wed,  4 Jun 2014 18:08:47 +1000
> Alexey Kardashevskiy <aik@ozlabs.ru> wrote:
> 
> > This introduces an NMI (non maskable interrupt) callback per CPU class
> > which QMP's "nmi" command may use to issue NMI on a CPU.
> > 
> > This adds support for it in qmp_inject_nmi(). Since no architecture
> > supports it at the moment, there is no change in behaviour.
> > 
> > This changes inject-nmi command description for HMP and QMP.
> > 
> > Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> > ---
> > Changes:
> > v3:
> > * actual nmi() enablement moved from last patch to first patch
> > * changed description for QMP command too
> > ---
> >  cpus.c            | 11 ++++++++++-
> >  hmp-commands.hx   |  6 ++----
> >  include/qom/cpu.h |  1 +
> >  qapi-schema.json  |  4 +---
> >  qmp-commands.hx   |  3 +--
> >  5 files changed, 15 insertions(+), 10 deletions(-)
> > 
> > diff --git a/cpus.c b/cpus.c
> > index dd7ac13..a000bd8 100644
> > --- a/cpus.c
> > +++ b/cpus.c
> > @@ -1495,6 +1495,15 @@ void qmp_inject_nmi(Error **errp)
> >          }
> >      }
> >  #else
> > -    error_set(errp, QERR_UNSUPPORTED);
> > +    CPUState *cs = qemu_get_cpu(monitor_get_cpu_index());
> > +    CPUClass *cc = CPU_GET_CLASS(cs);
> > +    int ret = -1;
> > +
> > +    if (cs && cc->nmi) {
> > +        ret = cc->nmi(cs);
> > +    }
> > +    if (ret) {
> > +        error_set(errp, QERR_UNSUPPORTED);
> > +    }
> >  #endif
> >  }
> > diff --git a/hmp-commands.hx b/hmp-commands.hx
> > index 2e462c0..e97b5ec 100644
> > --- a/hmp-commands.hx
> > +++ b/hmp-commands.hx
> > @@ -830,19 +830,17 @@ The values that can be specified here depend on the machine type, but are
> >  the same that can be specified in the @code{-boot} command line option.
> >  ETEXI
> >  
> > -#if defined(TARGET_I386) || defined(TARGET_S390X)
> >      {
> >          .name       = "nmi",
> >          .args_type  = "",
> >          .params     = "",
> > -        .help       = "inject an NMI on all guest's CPUs",
> > +        .help       = "inject an NMI on the given guest's CPU",
> >          .mhandler.cmd = hmp_inject_nmi,
> >      },
> > -#endif
> >  STEXI
> >  @item nmi @var{cpu}
> >  @findex nmi
> > -Inject an NMI (x86) or RESTART (s390x) on the given CPU.
> > +Inject an NMI on the given CPU.
> >  
> >  ETEXI
> >  
> > diff --git a/include/qom/cpu.h b/include/qom/cpu.h
> > index df977c8..b34f23b 100644
> > --- a/include/qom/cpu.h
> > +++ b/include/qom/cpu.h
> > @@ -108,6 +108,7 @@ typedef struct CPUClass {
> >      void (*parse_features)(CPUState *cpu, char *str, Error **errp);
> >  
> >      void (*reset)(CPUState *cpu);
> > +    int (*nmi)(CPUState *cs);
> >      int reset_dump_flags;
> >      bool (*has_work)(CPUState *cpu);
> >      void (*do_interrupt)(CPUState *cpu);
> > diff --git a/qapi-schema.json b/qapi-schema.json
> > index 7bc33ea..dcf6642 100644
> > --- a/qapi-schema.json
> > +++ b/qapi-schema.json
> > @@ -1748,13 +1748,11 @@
> >  ##
> >  # @inject-nmi:
> >  #
> > -# Injects an Non-Maskable Interrupt into all guest's VCPUs.
> > +# Injects an Non-Maskable Interrupt into the given guest's VCPU.
> 
> QMP doesn't have the concept of "current monitored CPU" you talk in the
> intro email. In QMP you have to specify the CPU. You have to choices:
> 
>  - Add a new command that takes a CPU parameter (seems the best to me, as
>    people were asking for a different command anyways)
> 
>  - Add an optional parameter to inject-nmi. When the CPU parameter is
>    not specified, the command sends the NMI to all CPUs

The s390 restart interrupt is a per-vcpu interrupt, which we really
don't want to inject on _all_ vcpus. OTOH, we want to inject that
interrupt on any vcpu - we don't care which one it is. So I'd really
like an "inject nmi on default cpu" option.

> 
> Eric, any thoughts?
> 
> >  #
> >  # Returns:  If successful, nothing
> >  #
> >  # Since:  0.14.0
> > -#
> > -# Notes: Only x86 Virtual Machines support this command.
> >  ##
> >  { 'command': 'inject-nmi' }
> >  
> > diff --git a/qmp-commands.hx b/qmp-commands.hx
> > index d8aa4ed..553375b 100644
> > --- a/qmp-commands.hx
> > +++ b/qmp-commands.hx
> > @@ -477,7 +477,7 @@ SQMP
> >  inject-nmi
> >  ----------
> >  
> > -Inject an NMI on guest's CPUs.
> > +Inject an NMI on the given guest's CPU.
> >  
> >  Arguments: None.
> >  
> > @@ -487,7 +487,6 @@ Example:
> >  <- { "return": {} }
> >  
> >  Note: inject-nmi fails when the guest doesn't support injecting.
> > -      Currently, only x86 (NMI) and s390x (RESTART) guests do.
> >  
> >  EQMP
> >  
>