Re: [Qemu-devel] [PATCH] migration: notify runstate immediately before vcpu stops

[Yan Zhao <yan.y.zhao@intel.com>]

On Tue, Jul 16, 2019 at 03:23:16PM +0800, Peter Xu wrote:
> On Tue, Jul 16, 2019 at 03:10:42PM +0800, Yan Zhao wrote:
> > for some devices to do live migration, it is needed to do something
> > immediately before vcpu stops. add a notification here.
> 
> Hi, Yan,
> 
> Could I ask for a more detailed commit message here?  E.g., what is
> "some devices"?  And, what's the problem behind?
>
hi Peter,

Some devices refer to assigned devices, like NICs.
For assigned devices to do live migration, it is sometimes required that
source device is stopped before stopping source vcpus. vcpus can do some
final cleanups (like handling interrupt) in that case.

Thanks
Yan

> Thanks,
> 
> > 
> > Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
> > ---
> >  cpus.c | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/cpus.c b/cpus.c
> > index b09b702..d5d4abe 100644
> > --- a/cpus.c
> > +++ b/cpus.c
> > @@ -1068,6 +1068,7 @@ static int do_vm_stop(RunState state, bool send_stop)
> >      int ret = 0;
> >  
> >      if (runstate_is_running()) {
> > +        vm_state_notify(1, state);
> >          cpu_disable_ticks();
> >          pause_all_vcpus();
> >          runstate_set(state);
> > -- 
> > 2.7.4
> > 
> > 
> 
> -- 
> Peter Xu