[vbox-dev] Is perf_counter_paranoid now perf_event_paranoid?

Frank Mehnert Frank.Mehnert at Sun.COM
Mon Jun 14 00:06:48 PDT 2010


Sean,

On Saturday 12 June 2010, sean darcy wrote:
> With Fedora 13, 2.6.33.5-112, vbox gives this message:
>
> vboxdrv: Warning: 2.6.31+ kernel detected. Most likely the hardware
> performance
> vboxdrv: counter framework which can generate NMIs is active. You have
> to prevent
> vboxdrv: the usage of hardware performance counters by
> vboxdrv:   echo 2 > /proc/sys/kernel/perf_counter_paranoid
>
> But:
>
> ls /proc/sys/kernel/perf*
> /proc/sys/kernel/perf_event_max_sample_rate
> /proc/sys/kernel/perf_event_paranoid
> /proc/sys/kernel/perf_event_mlock_kb
>
> Is perf_counter_paranoid now perf_event_paranoid?

yes, you are right. Although this is a hack anyway. This hack should
prevent using the perf counter framework while a VirtualBox VM is
executed. The reason is that the perf counter code in newer Linux
kernels is able to generate an NMI (non-maskable interrupt) which
could (if it occurs at the wrong time) reboot the host. A proper
solution is still pending, the above hack should forbid at least
non-root users to use the perf counters.

Kind regards,

Frank
-- 
Dr.-Ing. Frank Mehnert

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Sun Microsystems GmbH, Sonnenallee 1, 85551 Kirchheim-Heimstetten
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