Re: [PATCH v2] kvm: reuse per-vcpu stats fd to avoid vcpu interruption

[Paolo Bonzini]

On 6/18/23 01:00, Philippe Mathieu-Daudé wrote:
> >       case STATS_TARGET_VCPU:
> >           add_stats_entry(result, STATS_PROVIDER_KVM,
> > -                        current_cpu->parent_obj.canonical_path,
> > +                        cpu->parent_obj.canonical_path,
>
> Can we get a NULL deref here ...
>
> >                           stats_list);
> >           break;
> >       default:
>
>
> >   static void query_stats_cb(StatsResultList **result, StatsTarget 
> > target,
> > @@ -4180,7 +4180,7 @@ static void query_stats_cb(StatsResultList 
> > **result, StatsTarget target,
> >               error_setg_errno(errp, errno, "KVM stats: ioctl failed");
> >               return;
> >           }
> > -        query_stats(result, target, names, stats_fd, errp);
> > +        query_stats(result, target, names, stats_fd, NULL, errp);
>
> ... from here?

No, target is STATS_TARGET_VM here.

In the kernel, KVM_GET_STATS_FD could also be improved because it does 
not need to take vcpu->mutex.  However that would not be enough; it 
would require QEMU changes anyway to remove run_on_cpu.  So I'm queuing 
the patch, thanks!

Paolo