[Qemu-devel] Re: [COMMIT 733318e] don't call cpu_sychronize_state from reset handlers

[Glauber Costa]

On Fri, Sep 11, 2009 at 01:52:05PM +0200, Jan Kiszka wrote:
> Glauber Costa wrote:
> > On Fri, Sep 11, 2009 at 01:15:49PM +0200, Jan Kiszka wrote:
> >> Anthony Liguori wrote:
> >>> From: Glauber Costa <address@hidden>
> >>>
> >>> Doing this will make the vcpu ioctl be issued from the I/O thread, instead
> >>> of cpu thread. The correct behaviour is to call it from within the cpu 
> >>> thread,
> >>> as soon as we are ready to go.
> >> Note that in the good old days, this used to work properly (in qemu-kvm)
> >> as registers write-back was routed through on_vcpu.
> > 
> > I believe we should avoid the use of those things, specially at 
> > initialization. They are
> > totally racy and fragile. One way to do that, is to do all the reset 
> > functions inside the
> > cpu thread.
> 
> As all this used to work fine in practice in upstream as well as in
> qemu-kvm, I'm slightly unhappy about the current situation.
> 
> > 
> > I already have something hacked up for this, will send as soon as I finish 
> > testing.
> 
> OK, looking forward.
> 
> BTW, what's the state of the fix for the guest-debug regression under KVM?
The last proposal I sent for queue_work would fix it, but it is a too big job, 
for just a fix.
If you are not using the IO thread, I can do what I did in there: define 
on_vcpu to be
conditional to the I/O thread, and in case it is not defined, just call the 
function

What do you think?