[Xen-devel] Re: [PATCH 08/13] xen/pvticketlock: disable interrupts while blocking

[Andi Kleen <andi@xxxxxxxxxxxxxx>]

On Wed, Sep 14, 2011 at 10:00:07AM +0300, Avi Kivity wrote:
> On 09/13/2011 10:21 PM, Don Zickus wrote:
> >Or are you saying an NMI in an idle system will have the same %rip thus
> >falsely detecting a back-to-back NMI?
> >
> >
> 
> That's easy to avoid - insert an instruction zeroing the last nmi_rip 
> somewhere before or after hlt.  It's always okay to execute such an 
> instruction (outside the nmi handler itself), since nmi_rip is meant to 
> detect a "no instructions executed" condition.

At least for classic hlt there is no simple "after hlt" because it's all
interrupt handlers and exceptions and everything else that can interrupt
combined.

It may work with newer MWAIT.

-Andi

-- 
ak@xxxxxxxxxxxxxxx -- Speaking for myself only.

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