On Tue, Jul 06, 2021 at 12:14:16PM -0700, Nathan Chancellor wrote: > On 7/6/2021 10:06 AM, Will Deacon wrote: > > 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. > > For what it's worth, I attempted to boot Will's diff on top of Konrad's > devel/for-linus-5.14 and it did not work; in fact, I got no output on my > monitor period, even with earlyprintk=, and I do not think this machine has > a serial console. Looking back at the diff, I completely messed up swiotlb_exit() by mixing up physical and virtual addresses. > Robin's fix does work, it survived ten reboots with no issues getting to X > and I do not see the KASAN and slub debug messages anymore but I understand > that this is not the preferred solution it seems (although Konrad did want > to know if it works). > > I am happy to test any further patches or follow ups as needed, just keep me > on CC. Cheers. Since this isn't 5.14 material any more, I'll CC you on a series next week. Will
