Re: [PATCH-next] kvm: don't try to take mmu_lock while holding the main raw kvm_lock

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On 2013-06-27 13:38, Paolo Bonzini wrote:
> Il 27/06/2013 13:09, Gleb Natapov ha scritto:
>> On Tue, Jun 25, 2013 at 06:34:03PM -0400, Paul Gortmaker wrote:
>>> In commit e935b8372cf8 ("KVM: Convert kvm_lock to raw_spinlock"),
>> I am copying Jan, the author of the patch. Commit message says:
>> "Code under this lock requires non-preemptibility", but which code
>> exactly is this? Is this still true?
> 
> hardware_enable_nolock/hardware_disable_nolock does.

IIRC, also the loop in kvmclock_cpufreq_notifier needs it because it
reads the processor ID of the caller. That implies the caller cannot be
preempted, but theses days a migration lock should be fine as well.

Jan

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Corporate Competence Center Embedded Linux
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