Re: [PATCH v15 06/12] swiotlb: Use is_swiotlb_force_bounce for swiotlb data bouncing

[Will Deacon]

On Tue, Jul 06, 2021 at 04:39:11PM +0100, Robin Murphy wrote:
> On 2021-07-06 15:05, 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.
> 
> Ah yes, that had slipped my mind, and it's a fair point indeed. Since we're
> not concerned with a minimal fix for backports anyway I'm more than happy to
> focus on Will's approach. Another thing is that that looks to take us a
> quiet step closer to the possibility of dynamically resizing a SWIOTLB pool,
> which is something that some of the hypervisor protection schemes looking to
> build on top of this series may want to explore at some point.

Ok, I'll split that nasty diff I posted up into a reviewable series and we
can take it from there.

Will