Messages in this thread | | | Date | Mon, 15 Dec 2008 20:05:09 +0100 | From | Andreas Herrmann <> | Subject | Re: [PATCH 2/2] x86: re-enable MCE on secondary CPUS after suspend/resume |
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On Fri, Dec 12, 2008 at 08:06:21PM +0100, Andi Kleen wrote: > Andreas Herrmann <andreas.herrmann3@amd.com> writes: > > > Impact: fix suspend/resume bug with MCE > > > > After suspend/resume MCx_CTL registers of secondary CPUs are cleared. > > (At least that's what I've observed on several systems.) > > Linux currently only re-initializes MCE on the boot CPU - see mce_resume(). > > Thus after suspend/resume we end up with a system where MCE is active > > on the boot CPU but switched off on all other CPUs. > > > > By calling mce_init() whenever a CPU comes online this problem is > > solved. > > Can you double check that please? > > Suspend/resume are supposted to hotunplug all CPUs except the BP and > then re-online them on resume (with "disable_nonboot_cpus()) . The > re-online initializes MCEs in the standard CPU bootup path.
For BP we have
/* On resume clear all MCE state. Don't want to see leftovers from the BIOS. Only one CPU is active at this time, the others get readded later using CPU hotplug. */ static int mce_resume(struct sys_device *dev) { mce_init(NULL); return 0; }
For APs mcheck_init() is called on resume. But as the respective bit for an AP is usually set in "mce_cpus" after boot (which is correct, I think) mcheck_init does not call mce_init, see:
void __cpuinit mcheck_init(struct cpuinfo_x86 *c) { static cpumask_t mce_cpus = CPU_MASK_NONE;
mce_cpu_quirks(c);
if (mce_dont_init || cpu_test_and_set(smp_processor_id(), mce_cpus) || !mce_available(c)) => return;
mce_init(NULL); mce_cpu_features(c); }
But we need to call mce_init to clear all MCE state. IMHO the best location to call mce_init for APs is the cpu notifier.
Regards,
Andreas
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