On 2016.11.22 14:38:19 +0000, Chris Wilson wrote: > On Tue, Nov 22, 2016 at 09:29:40PM +0800, Zhi Wang wrote: > > Hi guys: > > Would you mind to have a quick review on this patch? :P The > > linux guest under GVT-g couldn't boot up without this patch in the > > newer kernel. > > > > Thanks, > > Zhi. > > > > On 11/21/16 19:44, Zhi Wang wrote: > > >a PT page will be released if it doesn't contain any meaningful mappings > > >during PPGTT page table shrinking. The PT entry in the upper level will > > >be set to a scratch entry. > > > > > >Normally this works nicely, but in virtualization world, the PPGTT page > > >table is tracked by hypervisor. Releasing the PT page before modifying > > >the upper level PT entry would cause extra efforts. > > > > > >As the tracked page has been returned to OS before losing track from > > >hypervisor, it could be written in any pattern. Hypervisor has to recognize > > >if a page is still being used as a PT page by validating these writing > > >patterns. It's complicated. Better let the guest modify the PT entry in > > >upper level PT first, then release the PT page. > > > > > >Cc: Michał Winiarski <michal.winiarski@xxxxxxxxx> > > >Cc: Michel Thierry <michel.thierry@xxxxxxxxx> > > >Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx> > > >Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > > >Cc: Zhenyu Wang <zhenyuw@xxxxxxxxxxxxxxx> > > >Cc: Zhiyuan Lv <zhiyuan.lv@xxxxxxxxx> > > >Signed-off-by: Zhi Wang <zhi.a.wang@xxxxxxxxx> > > The original didn't make it to me, so I just assumed a list issue. > > For the record, I'd like to have some more detail on just when the hv is > doing the page scanning. It makes it sound like you are actively > scanning an idle range. > > Reviewed-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> Note that this should be queued for 4.9 fix otherwise 4.9 will be broken as guest kernel version for GVT-g. Thanks -- Open Source Technology Center, Intel ltd. $gpg --keyserver wwwkeys.pgp.net --recv-keys 4D781827
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