Re: [Qemu-devel] [PATCH 03/16] introduce resume_vcpu(), for single CPU

[Igor Mammedov <imammedo@redhat.com>]

On Mon, 22 Apr 2013 13:40:02 +0300
Gleb Natapov <gleb@redhat.com> wrote:

> On Tue, Apr 16, 2013 at 12:12:43AM +0200, Igor Mammedov wrote:
> > ... also add stub for it, to make possible to use it in qom/cpu.c,
> > which is shared with user emulators.
> > 
> > Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> > ---
> > Note:
> >   it will be re-used from qom/cpu.c by hotpluged CPU
> > ---
> >  cpus.c              | 11 ++++++++---
> >  include/qom/cpu.h   |  9 +++++++++
> >  stubs/Makefile.objs |  1 +
> >  stubs/cpus.c        |  5 +++++
> >  4 files changed, 23 insertions(+), 3 deletions(-)
> >  create mode 100644 stubs/cpus.c
> > 
> > diff --git a/cpus.c b/cpus.c
> > index c15ff6c..c347db5 100644
> > --- a/cpus.c
> > +++ b/cpus.c
> > @@ -993,6 +993,13 @@ void pause_all_vcpus(void)
> >      }
> >  }
> >  
> > +void resume_vcpu(CPUState *cpu)
> > +{
> > +    cpu->stop = false;
> > +    cpu->stopped = false;
> > +    qemu_cpu_kick(cpu);
> > +}
> > +
> >  void resume_all_vcpus(void)
> >  {
> >      CPUArchState *penv = first_cpu;
> > @@ -1000,9 +1007,7 @@ void resume_all_vcpus(void)
> >      qemu_clock_enable(vm_clock, true);
> >      while (penv) {
> >          CPUState *pcpu = ENV_GET_CPU(penv);
> > -        pcpu->stop = false;
> > -        pcpu->stopped = false;
> > -        qemu_cpu_kick(pcpu);
> > +        resume_vcpu(pcpu);
> >          penv = penv->next_cpu;
> >      }
> >  }
> > diff --git a/include/qom/cpu.h b/include/qom/cpu.h
> > index 3664a1b..6ce6f10 100644
> > --- a/include/qom/cpu.h
> > +++ b/include/qom/cpu.h
> > @@ -256,5 +256,14 @@ void cpu_interrupt(CPUState *cpu, int mask);
> >   */
> >  void cpu_reset_interrupt(CPUState *cpu, int mask);
> >  
> > +/**
> > + * resume_vcpu:
> > + * @cpu: The CPU to resume.
> > + *
> > + * Resumes CPU, i.e. puts CPU into runable state.
> > + * KVM requires extra call cpu_synchronize_post_init() to make
> > + * KVM's CPU instance runable.
> > + */
> Can you elaborate on this a bit. Why is it needed and why is it relevant
> for this function?
If running in KVM mode and resume_vcpu() is called without
cpu_synchronize_post_init(), then CPU instance in KVM will be
left in UNCONFIGURED state. I've added comment here to document 
that resume_vcpu() isn't enough to make CPU run-able in case of KVM.

> 
> > +void resume_vcpu(CPUState *cpu);
> >  
> >  #endif
> > diff --git a/stubs/Makefile.objs b/stubs/Makefile.objs
> > index 9c55b34..03dff20 100644
> > --- a/stubs/Makefile.objs
> > +++ b/stubs/Makefile.objs
> > @@ -23,3 +23,4 @@ stub-obj-y += sysbus.o
> >  stub-obj-y += vm-stop.o
> >  stub-obj-y += vmstate.o
> >  stub-obj-$(CONFIG_WIN32) += fd-register.o
> > +stub-obj-y += cpus.o
> > diff --git a/stubs/cpus.c b/stubs/cpus.c
> > new file mode 100644
> > index 0000000..3d17451
> > --- /dev/null
> > +++ b/stubs/cpus.c
> > @@ -0,0 +1,5 @@
> > +#include "qom/cpu.h"
> > +
> > +void resume_vcpu(CPUState *cpu)
> > +{
> > +}
> > -- 
> > 1.8.2
> > 
> > 
> 
> --
> 			Gleb.