On Wed, Jul 20, 2022 at 04:08:10PM -0700, Vishal Annapurve wrote: > > > Hmm, so a new slot->arch.page_attr array shouldn't be necessary, KVM can instead > > > update slot->arch.lpage_info on shared<->private conversions. Detecting whether > > > a given range is partially mapped could get nasty if KVM defers tracking to the > > > backing store, but if KVM itself does the tracking as was previously suggested[*], > > > then updating lpage_info should be relatively straightfoward, e.g. use > > > xa_for_each_range() to see if a given 2mb/1gb range is completely covered (fully > > > shared) or not covered at all (fully private). > > > > > > [*] https://lore.kernel.org/all/YofeZps9YXgtP3f1@xxxxxxxxxx > > > > Yes, slot->arch.page_attr was introduced to help identify whether a page > > is completely shared/private at given level. It seems XARRAY can serve > > the same purpose, though I know nothing about it. Looking forward to > > seeing the patch of using XARRAY. > > > > yes, update slot->arch.lpage_info is good to utilize the existing logic > > and Isaku has applied it to slot->arch.lpage_info for 2MB support patches. > > Chao, are you planning to implement these changes to ensure proper > handling of hugepages partially mapped as private/shared in subsequent > versions of this series? > Or is this something left to be handled by the architecture specific code? Ah, the topic gets moved to a different place. I should update here. There were more discussions under TDX KVM patch series and I actually just sent out the draft code for this: https://lkml.org/lkml/2022/7/20/610 That patch is based on UPM v7 here. If I can get more feedbacks there then I will include an udpated version in UPM v8. If you have bandwdith, you can also play with that patch, any feedback is welcome. Chao > > Regards, > Vishal
