linux-kernel - Re: [PATCH] kvm: disable stealtime via reboot notifier to avoid mem corruption

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Message-ID: <20120814091506.GA13610@breakpoint.cc>
Date:	Tue, 14 Aug 2012 11:15:06 +0200
From:	Florian Westphal <fw@...len.de>
To:	Marcelo Tosatti <mtosatti@...hat.com>
Cc:	Florian Westphal <fw@...len.de>, kvm@...r.kernel.org,
	avi@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kvm: disable stealtime via reboot notifier to avoid
 mem corruption

Marcelo Tosatti <mtosatti@...hat.com> wrote:
> On Fri, Aug 10, 2012 at 12:36:22PM +0200, Florian Westphal wrote:
> > --- a/arch/x86/kernel/kvmclock.c
> > +++ b/arch/x86/kernel/kvmclock.c
> > @@ -191,7 +191,6 @@ static void kvm_crash_shutdown(struct pt_regs *regs)
> >  static void kvm_shutdown(void)
> >  {
> >  	native_write_msr(msr_kvm_system_time, 0, 0);
> > -	kvm_disable_steal_time();
> >  	native_machine_shutdown();
> >  }
> This part below will introduce a bug for shutdown. Can you retest with
> the addition of kvm_disable_steal_time to kvm_pv_guest_cpu_reboot only,
> retest and resend please?

I can, but the problem with kvm_disable_steal_time() in
kvmclock.c is that with CONFIG_KVM_CLOCK=n the entire
file won't be compiled.

And steal time doesn't depend on CONFIG_KVM_CLOCK=y.
So if removing it there is a bug leaving it in only avoids
that bug for CONFIG_KVM_CLOCK=y.


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