Messages in this thread Patch in this message | | | Date | Tue, 25 Aug 2009 12:53:02 -0700 | From | Jeremy Fitzhardinge <> | Subject | Re: [PATCH] x86: Execute WP test after interrupts are enabled |
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On 08/25/09 12:38, Pekka Enberg wrote: > On Tue, 2009-08-25 at 12:34 -0700, Jeremy Fitzhardinge wrote: > >> I don't think this is the real fix, and it seems a bit ugly. I'm OK >> with it as a workaround, but I think it will end up getting reverted if >> applied. >> > Yeah, I'm fine with that. It's just that we're really late in the > release cycle now so I'd like to keep the fix as simple as possible.
Yeah, that's fine, but I think something like this would be simpler. Arnd, could you test it please?
From: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Date: Tue, 25 Aug 2009 12:47:17 -0700 Subject: [PATCH] xen: suppress WP test
Xen always runs on CPUs which properly support WP enforcement in privileged mode, so there's no need to test for it.
This also works around a crash reported by Arnd Hannemann, though I think its just a band-aid for that case.
Reported-by: Arnd Hannemann <hannemann@nets.rwth-aachen.de> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: Pekka Enberg <penberg@cs.helsinki.fi>
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c index 16d0d70..e5b903b 100644 --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -1069,6 +1069,7 @@ asmlinkage void __init xen_start_kernel(void) /* set up basic CPUID stuff */ cpu_detect(&new_cpu_data); new_cpu_data.hard_math = 1; + new_cpu_data.wp_works_ok = 1; new_cpu_data.x86_capability[0] = cpuid_edx(1); #endif
> Do you think the real bug lies in Xen or...? >
I'm unsure. If handling a trap ends up enabling interrupts for some reason, then things would break horribly all over the place, so it would have to be something a bit more subtle. I'm looking into it.
J
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