Re: [Xen-devel] [PATCH v4 3/3] VT-d: Fix vt-d Device-TLB flush timeout issue.

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> Sent: Tuesday, January 26, 2016 11:53 PM
> 
> >> > At first, I am open for any solution.
> >> > pcidevs_lock is quite a big lock. For this point, it looks much better
> >> > to add a new flag to delay hiding device.
> >> > I am also afraid that it may raise further security issues.
> >>
> >> Well, I'd say just go and see which one turns out to be less cumbersome
> > and/or
> >> less intrusive.
> >>
> > For this lock, any good idea?
> > IMO, I can get started to add a new flag to delay hiding device.
> 
> Once again: Before getting started, please assess which route is
> going to be the better one. Remember that we had already
> discussed and put aside some form of deferring the hiding of
> devices, so if you come back with a patch doing that again, you'll
> have to be able to explain why the alternative(s) are worse.
> 

Quan, could you list pros/cons of those alternatives based on
discussion so far? Then we can decide which way should be
done before you go to actual coding. Earlier suggestion on
hiding device immediately is under the assumption that all
locks have been held. If this part becomes too complex, and
you can explain clearly that deferring the hiding action doesn't
lead to any race condition, then people can see why you are
proposing defer again.

Thanks
Kevin

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