Re: [kvm-devel] [PATCH 3/3] KVM - add hypercall nr to kvm_run

[Anthony Liguori]

Avi Kivity wrote:
> Jeff Dike wrote:
>   
> > Add the hypercall number to kvm_run and initialize it.  This might be
> > considered API-changing, so I kept it separate.
> >
> > Signed-off-by: Jeff Dike <jdike@xxxxxxxxxxxxxxx>
> > --
> >  drivers/kvm/kvm_main.c |    1 +
> >  include/linux/kvm.h    |    1 +
> >  2 files changed, 2 insertions(+)
> >
> > Index: kvm/drivers/kvm/kvm_main.c
> > ===================================================================
> > --- kvm.orig/drivers/kvm/kvm_main.c
> > +++ kvm/drivers/kvm/kvm_main.c
> > @@ -1361,6 +1361,7 @@ int kvm_hypercall(struct kvm_vcpu *vcpu,
> >  	}
> >  	switch (nr) {
> >  	default:
> > +		run->hypercall.nr = nr;
> >  		run->hypercall.args[0] = a0;
> >  		run->hypercall.args[1] = a1;
> >  		run->hypercall.args[2] = a2;
> > Index: kvm/include/linux/kvm.h
> > ===================================================================
> > --- kvm.orig/include/linux/kvm.h
> > +++ kvm/include/linux/kvm.h
> > @@ -106,6 +106,7 @@ struct kvm_run {
> >  		} mmio;
> >  		/* KVM_EXIT_HYPERCALL */
> >  		struct {
> > +			__u64 nr;
> >  			__u64 args[6];
> >  			__u64 ret;
> >  			__u32 longmode;
> >   
> >     
>
> It isn't API changing as the API could not be (and has not been) used.  
> We do need to add a padding element to the union to make sure additional 
> union members don't cause its size to change.
>
> Quite sad that we got this far with such brokenness.
>   

I'm planning on breaking this interface again since the new hypercall 
API only takes 4 arguments instead of 6.

Regards,

Anthony Liguori

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