Re: [Xen-devel] [PATCH v4 2/6] VMX: Properly handle pi when all the assigned devices are removed

["Wu, Feng" <feng.wu@xxxxxxxxx>]

> >>
> >> So you continue using pausing, and I continue to miss the argumentation
> >> of why you can't do without (even if previously the discussion was for
> >> patch 4, but it obviously applies here as well).
> >
> > I think this case is slightly different. Here we need to call
> > vmx_pi_list_cleanup()
> > to remove the vCPU from the blocking list if it is on the list. However, 
> > this
> > can be happened when vmx_vcpu_block() is called, hence we might incorrectly
> > add the vcpu to the blocking list while the last device is detached from the
> domain.
> > In fact, v2 gave some trick methods to handle this, and that was considered 
> > as
> > hard to maintain, so George suggested to use pause/unpause for this case,
> and I
> > also think it is easy and acceptable consider that devices detaching is not 
> > a
> > frequent action.
> 
> Note how I said "I continue to miss the argumentation of why you
> can't do without" - I'm not opposed to pausing getting used here, but
> it needs to be at least briefly explained in the commit message. That's
> among other things so that (see that other thread) people can't later
> come and say "Hey, pausing is done in all sorts of situations, why
> won't you let me add some more pausing?"

Fair enough, I will elaborate a bit more on it.

Thanks,
Feng

> 
> Jan


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