linux-kernel - Re: [BUG] kvm crashes in 2.6.28-rc6-00007-ged31348

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Message-Id: <1228250921.4886.14.camel@localhost.localdomain>
Date:	Tue, 02 Dec 2008 15:48:41 -0500
From:	Steven Rostedt <srostedt@...hat.com>
To:	Avi Kivity <avi@...hat.com>
Cc:	Luis Henriques <henrix@...o.pt>, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org, Steven Rostedt <rostedt@...dmis.org>,
	Ingo Molnar <mingo@...e.hu>
Subject: Re: [BUG] kvm crashes in 2.6.28-rc6-00007-ged31348


On Tue, 2008-12-02 at 22:38 +0200, Avi Kivity wrote:
> Steven Rostedt wrote:
> > The following must be available without recursion for the function
> > tracer to work:
> >
> >   local_irq_save/restore
> >   smp_processor_id
> >   preempt_enable/disable_notrace
> >   atomic_inc/dec
> >   
> 
> In arch/x86/kvm/svm.c, function svm_vcpu_run(), everything between the 
> vmrun instruction and the call to load_host_msrs() is executed without a 
> live pda, so no smp_processor_id().  Could easily be fixed by 
> rearranging things.

That would be best, but if you have trouble, you could surround the
trouble area with a: tracing_stop(); tracing_start(); That will prevent
tracing within those locations. The function tracer will still be
called, but it will exit the function without doing anything else.

Note: that stops tracing on all CPUS, not just the CPU that called it.

-- Steve


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