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Date:   Tue, 6 Jul 2021 10:46:07 -0400
From:   Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To:     Christoph Hellwig <hch@lst.de>
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Subject: Re: [PATCH v15 06/12] swiotlb: Use is_swiotlb_force_bounce for
 swiotlb data bouncing
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References: <20210701074045.GA9436@willie-the-truck>
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 <0f7bd903-e309-94a0-21d7-f0e8e9546018@arm.com>
 <YN/7xcxt/XGAKceZ@Ryzen-9-3900X.localdomain>
 <20210705190352.GA19461@willie-the-truck>
 <20210706044848.GA13640@lst.de>
 <20210706132422.GA20327@willie-the-truck>
 <a59f771f-3289-62f0-ca50-8f3675d9b166@arm.com>
 <20210706140513.GA26498@lst.de>
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On Tue, Jul 06, 2021 at 04:05:13PM +0200, Christoph Hellwig wrote:
> On Tue, Jul 06, 2021 at 03:01:04PM +0100, Robin Murphy wrote:
> > FWIW I was pondering the question of whether to do something along those 
> > lines or just scrap the default assignment entirely, so since I hadn't got 
> > round to saying that I've gone ahead and hacked up the alternative 
> > (similarly untested) for comparison :)
> >
> > TBH I'm still not sure which one I prefer...
> 
> Claire did implement something like your suggestion originally, but
> I don't really like it as it doesn't scale for adding multiple global
> pools, e.g. for the 64-bit addressable one for the various encrypted
> secure guest schemes.

Couple of things:
 - I am not pushing to Linus the Claire's patchset until we have a
   resolution on this. I hope you all agree that is a sensible way
   forward as much as I hate doing that.

 - I like Robin's fix as it is simplest looking. Would love to see if it
   does fix the problem.

 - Christopher - we can always add multiple pools as the next milestone
   and just focus on this feature getting tested extensively during this
   release.

 - Would it be worth (for future or maybe in another tiny fix) to also add
   a printk in swiotlb when we de-allocate the buffer so when someone looks
   through the `dmesg` it becomes much easier to diagnose issues?