On Mon, 19 Jul 2021 14:39:05 +0100, Quentin Perret <qperret@xxxxxxxxxx> wrote: > > On Monday 19 Jul 2021 at 13:55:29 (+0100), Marc Zyngier wrote: > > On Mon, 19 Jul 2021 11:47:26 +0100, > > Quentin Perret <qperret@xxxxxxxxxx> wrote: > > > > > > The nVHE protected mode uses invalid mappings in the host stage-2 > > > page-table to track the owner of each page in the system. In order to > > > allow the usage of ignored bits (a.k.a. software bits) in these > > > mappings, move the owner encoding away from the top bits. > > > > But that's exactly what the current situation is allowing: the use of > > the SW bits. I am guessing that what you really mean is that you want > > to *preserve* the SW bits from an existing mapping and use other bits > > when the mapping is invalid? > > Yes, this is really just forward looking, but I think it might be useful > to allow annotating invalid mappings with both an owner id _and_ > additional flags for e.g. shared pages and such. And using bits [58-55] > to store those flags just like we do for valid mappings should make > things easier, but no big deal. Right, so maybe worth calling that out. > I see how this is going to conflict with kvm_pgtable_stage2_annotate() > from your series though, so maybe I should just drop this patch and > leave the encoding 'issue' to the caller -- the rest of the series > doesn't depend on this anyway, this was just small cleanup. I'm not too worried about that for now. We can always rewrite one in terms of the other, but I wanted to understand exactly this change was about. Thanks, M. -- Without deviation from the norm, progress is not possible. _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
