Messages in this thread | | | Date | Fri, 10 Mar 2017 01:13:54 +0100 | From | Daniel Borkmann <> | Subject | Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request at 0000a7cf |
| |
On 03/10/2017 12:44 AM, Borislav Petkov wrote: > On Thu, Mar 09, 2017 at 03:26:02PM -0800, Linus Torvalds wrote: >> So should all of commit ("c109bf95992b x86/cpufeature: Remove >> cpu_has_pge") just be reverted (and then marked for stable)? >> >> Or do we have some alternate plan? > > I think we want to do this: > > diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h > index 6fa85944af83..fc5abff9b7fd 100644 > --- a/arch/x86/include/asm/tlbflush.h > +++ b/arch/x86/include/asm/tlbflush.h > @@ -188,7 +188,7 @@ static inline void __native_flush_tlb_single(unsigned long addr) > > static inline void __flush_tlb_all(void) > { > - if (static_cpu_has(X86_FEATURE_PGE)) > + if (boot_cpu_has(X86_FEATURE_PGE)) > __flush_tlb_global(); > else > __flush_tlb(); > --- > > but it is late here so I'd prefer to do a real patch tomorrow when I'm > not almost sleeping on the keyboard. Unless Daniel wants to write one > and test it now.
I think we're in the same time zone. ;) I could send something official tomorrow cooking a changelog with analysis, but I don't mind at all if you want to go ahead with that either. Feel free to add my SoB or Tested-by to it.
>> This has apparently been going on for a long while (it got merged into >> 4.7), but presumably it only actually _matters_ if lguest is enabled >> and used and we've triggered that lguest_arch_host_init() code. > > That's what I gather too, yes. > > What sane code would go and clear X86_FEATURE_PGE?!? :-))) > >> Maybe it's the lguest games with PGE that need to be removed? > > Well, as far as I can read the comment in lguest_arch_host_init(), it > does some monkey business with switching to the guest kernel where > global pages are not present anymore... or something. So it sounds to me > like lguest would break if we removed the games but I have no idea what > it does with that. > > And besides, the small hunk above restores the situation before > ("c109bf95992b x86/cpufeature: Remove cpu_has_pge") so applying it would > actually be a no-brainer.
Agree, looks only that hunk changed in behavior from c109bf95992b ("x86/cpufeature: Remove cpu_has_pge").
> Thanks.
| |