Re: [kvm-devel] [PATCH 4/4] Modify KVM to update guest time accounting.

[Avi Kivity <avi@qumranet.com>]

Laurent Vivier wrote:
> Avi Kivity wrote:
>   
> > Laurent Vivier wrote:
> >     
> > > [PATCH 4/4] Modify KVM to update guest time accounting.
> > >
> > >   
> > >       
> > > Index: kvm/drivers/kvm/kvm.h
> > > ===================================================================
> > > --- kvm.orig/drivers/kvm/kvm.h    2007-08-20 13:23:53.000000000 +0200
> > > +++ kvm/drivers/kvm/kvm.h    2007-08-20 13:23:58.000000000 +0200
> > > @@ -589,6 +589,17 @@ void kvm_mmu_unload(struct kvm_vcpu *vcp
> > >  
> > >  int kvm_hypercall(struct kvm_vcpu *vcpu, struct kvm_run *run);
> > >  
> > > +static inline void kvm_guest_enter(void)
> > > +{
> > > +#ifdef CONFIG_GUEST_ACCOUNTING
> > > +    current->flags |= PF_VCPU;
> > > +#endif
> > >   
> > >       
> > Since you select GUEST_ACCOUNTING, the #ifdef is always true?
> >     
>
> It is just to avoid error if we compile kvm module outside of the kernel, with
> kernel without support of guest accounting. Can be removed if you want.
>
>   

Ah okay.  We take care of the external module in 
external-module-compat.h (in this case, we can #define PF_VCPU to 0 if 
it is undefined).

> > > +}
> > > +
> > > +static inline void kvm_guest_exit(void)
> > > +{
> > >   
> > >       
> > Missing content?
> >     
>
> No, empty function.
>
> It is just to introduce "symmetry" in code, the VCPU code begins with
> "kvm_guest_start()" and ends with "kvm_guest_exit()". And we have no operation
> to do in kvm_guest_exit() (the PF_VCPU is cleared by account_system_time()), so
> "empty function", removed by the optimizer (I hope).
>   

But what if account_system_time() is not called (because we exited 
before the timer interrupt hit)?


--
error compiling committee.c: too many arguments to function

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