On Thu, Jun 27, 2013 at 02:16:07PM +0200, Jan Kiszka wrote:
> 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.
>
OK, adding Marcelo to the party. This code is called from cpufreq
notifier. I would expect that it will be called from the context that
prevents migration to another cpu.
--
Gleb.
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