On Thu, 23 Aug, at 09:37:28AM, Roland Dreier wrote: > > > This is bad enough that 4.4.148 and all newer 4.4.y crash early in > > > boot on some EFI systems that I have. > > > > Ugh, not good. > > > > > For now I am re-applying the "ensure cpa->pfn only contains page frame > > > numbers" patch, ported on top of 4.4.151. > > > > I can try to add it back and see what blows up, want me to attempt that? > > Not sure what to say... the current state is obviously broken. If you > look at what 02ff2769edbc is doing, it's clear that we're now shifting > cpa->pfn by PAGE_SHIFT where we weren't before, so we're putting bogus > values in the page table. And this is enough that my server system > booting with EFI crashes early in boot efi_enter_virtual_mode() with > the symptom that NX is improperly set on some pages (booting with > "noexec=off" fixes things, although obviously I don't want to run that > way). FWIW I can confirm that reverting the single patch 02ff2769edbc > fixes things, as does the cpa->pfn fix I mentioned above. > > It's hard for me to make a call on applying "ensure cpa->pfn only > contains page frame numbers" without knowing the problems it caused > before. The patch looks fine to me and I definitely need it, but > maybe it exposes some other bug elsewhere? Maybe Ben or Matt remember > more above why this was reverted in 4.4.106? Otherwise I'd say yeah, > we should re-apply it, since I don't think we want to revert > 02ff2769edbc. For the record, I wasn't even aware it had been reverted.
