Il 20/08/2014 03:03, David Matlack ha scritto: > On Tue, Aug 19, 2014 at 5:29 PM, Xiao Guangrong > <xiaoguangrong@xxxxxxxxxxxxxxxxxx> wrote: >> On 08/19/2014 05:03 PM, Paolo Bonzini wrote: >>> Il 19/08/2014 10:50, Xiao Guangrong ha scritto: >>>> Okay, what confused me it that it seems that the single line patch >>>> is ok to you. :) >>> >>> No, it was late and I was confused. :) >>> >>>> Now, do we really need to care the case 2? like David said: >>>> "Sorry I didn't explain myself very well: Since we can get a single wrong >>>> mmio exit no matter what, it has to be handled in userspace. So my point >>>> was, it doesn't really help to fix that one very specific way that it can >>>> happen, because it can just happen in other ways. (E.g. update memslots >>>> occurs after is_noslot_pfn() and before mmio exit)." >>>> >>>> What's your idea? >>>> >>>>> I think if you always treat the low bit as zero in mmio sptes, you can >>>>> do that without losing a bit of the generation. >>>> >>>> What's you did is avoiding cache a invalid generation number into spte, but >>>> actually if we can figure it out when we check mmio access, it's ok. Like the >>>> updated patch i posted should fix it, that way avoids doubly increase the number. >>> >>> Yes. >>> >>>> Okay, if you're interested increasing the number doubly, there is the simpler >>>> one: >>> >>> This wastes a bit in the mmio spte though. My idea is to increase the >>> memslots generation twice, but drop the low bit in the mmio spte. >> >> Yeah, really smart idea. :) >> >> Paolo/David, would you mind making a patch for this (+ the comments in David's >> patch)? > > Paolo, since it was your idea would you like to write it? I don't mind either > way. Sure, I'll post the patch for review. Paolo -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
