Re: [Qemu-devel] [PATCH v2] target/s390x: Fix broken user mode

[Philippe Mathieu-Daudé]

Hi Stefan, Richard.

On 03/16/2017 10:28 AM, David Hildenbrand wrote:
> On 02.03.2017 20:56, David Hildenbrand wrote:
> > Am 30.01.2017 um 14:15 schrieb Stefan Weil:
> > > Returning NULL from get_max_cpu_model results in a SIGSEGV runtime error.
> > >
> > > Signed-off-by: Stefan Weil <address@hidden>
> > > ---
> > >
> > > v2: Re-sent as v1 was damaged by my mailer.
> > >
> > > This is also broken in Debian.
> > >
> > > In addition, there is no default CPU ("any"), so binfmt and related
> > > actions currently don't work. I hacked my local installation by
> > > duplicating the "qemu" cpu definition for "any", but maybe there is
> > > a better solution.
> >
> > That should then already work.
> >
> > > Regards
> > > Stefan
> > >
> > >  target/s390x/cpu_models.c | 2 --
> > >  1 file changed, 2 deletions(-)
> > >
> > > diff --git a/target/s390x/cpu_models.c b/target/s390x/cpu_models.c
> > > index 2a894ee..6e34763 100644
> > > --- a/target/s390x/cpu_models.c
> > > +++ b/target/s390x/cpu_models.c
> > > @@ -660,7 +660,6 @@ static void check_compatibility(const S390CPUModel 
> > > *max_model,
> > >
> > >  static S390CPUModel *get_max_cpu_model(Error **errp)
> > >  {
> > > -#ifndef CONFIG_USER_ONLY
> > >      static S390CPUModel max_model;
> > >      static bool cached;
> > >
> > > @@ -680,7 +679,6 @@ static S390CPUModel *get_max_cpu_model(Error **errp)
> > >          cached = true;
> > >          return &max_model;
> > >      }
> > > -#endif
> > >      return NULL;
> > >  }
> >
> > I thought this was already picked up for stable...
> > But looks like only the "any" model fixup got.
> >
> > So
> >
> > Acked-by: David Hildenbrand <address@hidden>
>
> Ping, can somebody please pick this up?

I see at least two possible changes:

the nasty one to catch bug:

@@ -681,7 +681,7 @@ static S390CPUModel *get_max_cpu_model(Error **errp)
         return &max_model;
     }
 #endif
-    return NULL;
+    abort();
 }

and the nicer one to avoid SIGSEGV:

@@ -734,8 +734,10 @@ void s390_realize_cpu_model(CPUState *cs, Error **errp)
     }

     max_model = get_max_cpu_model(errp);
-    if (*errp) {
-        error_prepend(errp, "CPU models are not available: ");
+    if (max_model == NULL) {
+        if (*errp) {
+            error_prepend(errp, "CPU models are not available: ");
+        } else {
+            error_setg(errp, "CPU models are not available");
+        }
         return;
     }