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

["Xu, Quan" <quan.xu@xxxxxxxxx>]

> On January 18, 2016 at 11:32pm, <tim@xxxxxxx> wrote:
> At 10:46 +0000 on 14 Jan (1452768377), Xu, Quan wrote:
> > > It's not about how this specific thing can be fixed. I didn't check all 
> > > the code.
> > > There could be more examples, and in the future all new code need to
> > > be aware that the majority of IOMMU functions may have pdev->domain
> > > changed due to error. My concern is more that it's not a good
> > > design. I think it's natural to have a state changed only after all
> > > existing references in the call chain have been completed. Adding a new 
> > > flag
> to delay hiding device looks much clearer to me.
> >
> > It looks we are not on the same page for how to hide a device.
> > Actually I have implemented these two ideas with pci_hide_device() or
> > flag in previous versions.
> >
> > Andrew and Tim, what's your opinion?
> 
> I have no strong opinion, since this isn't my area (and really never was - I
> worked on address translation more than device allocation).
> Since you ask, I don't see anything wrong with hiding the device if you 
> already
> own all the locks, and I'd be inclined to make whatever changes are necessary
> ASAP after the error.  Deferring the change (and having all callers need to 
> look
> for the deferred error) sounds fragile.

Tim, thanks a lots. I always assumed that you know ALL of Xen..
I will follow current v4 implement and send out v5 ASAP.

- Quan

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