From mboxrd@z Thu Jan  1 00:00:00 1970
From: Marcelo Tosatti <mtosatti@redhat.com>
Subject: Re: [RFC PATCH v2 1/2] add support for Hyper-V reference time counter
Date: Wed, 22 May 2013 00:32:57 -0300
Message-ID: <20130522033257.GA16087@amt.cnet>
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 <20130522032847.GI14287@redhat.com>
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Cc: Vadim Rozenfeld <vrozenfe@redhat.com>, kvm@vger.kernel.org,
	pl@dlh.net
To: Gleb Natapov <gleb@redhat.com>
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On Wed, May 22, 2013 at 06:28:47AM +0300, Gleb Natapov wrote
> > > +	case HV_X64_MSR_TIME_REF_COUNT:
> > >  		r = true;
> > >  		break;
> > >  	}
> > > @@ -1827,6 +1829,29 @@ static int set_msr_hyperv_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data)
> > >  		if (__copy_to_user((void __user *)addr, instructions, 4))
> > >  			return 1;
> > >  		kvm->arch.hv_hypercall = data;
> > > +		local_irq_disable();
> > > +		kvm->arch.hv_ref_count = get_kernel_ns();
> > > +		local_irq_enable();
> > > +		break;
> > 
> > local_irq_disable/local_irq_enable not needed.
> >
> get_kernel_ns has WARN_ON(preemptible()) so at least preempt_disable()
> is needed, but all callers of the function disable interrupts.

OK. Its not necessary to disable interrupts (this is a left over of
kvm_guest_update_time).