On Wed, Sep 14, 2011 at 10:08:13AM +0300, Avi Kivity wrote:
> On 09/13/2011 11:58 PM, Don Zickus wrote:
> >Previous patches allow the NMI subsystem to process multipe NMI events
> >in one NMI. As previously discussed this can cause issues when an event
> >triggered another NMI but is processed in the current NMI. This causes the
> >next NMI to go unprocessed and become an 'unknown' NMI.
> >
> >To handle this, we first have to flag whether or not the NMI handler handled
> >more than one event or not. If it did, then there exists a chance that
> >the next NMI might be already processed. Once the NMI is flagged as a
> >candidate to be swallowed, we next look for a back-to-back NMI condition.
> >
> >This is determined by looking at the %rip from pt_regs. If it is the same
> >as the previous NMI, it is assumed the cpu did not have a chance to jump
> >back into a non-NMI context and execute code and instead handled another NMI.
> >
> >If both of those conditions are true then we will swallow any unknown NMI.
> >
> >There still exists a chance that we accidentally swallow a real unknown NMI,
> >but for now things seem better.
>
> Patch looks good, but the changelog is outdated.
Perhaps, but I tried rewriting most of it to reflect the current changes.
Was there something obvious in there that I missed? I re-read it a few
times and can't figure out what part might be outdated (not that I
disagree with you, I just want to update it).