[RFC PATCH 5/6] KVM: PPC: Book3E: Add ONE_REG AltiVec support

[Caraman Mihai Claudiu-B02008]

> -----Original Message-----
> From: Wood Scott-B07421
> Sent: Wednesday, June 05, 2013 1:40 AM
> To: Caraman Mihai Claudiu-B02008
> Cc: kvm-ppc at vger.kernel.org; kvm at vger.kernel.org; linuxppc-
> dev at lists.ozlabs.org; Caraman Mihai Claudiu-B02008
> Subject: Re: [RFC PATCH 5/6] KVM: PPC: Book3E: Add ONE_REG AltiVec
> support
> 
> On 06/03/2013 03:54:27 PM, Mihai Caraman wrote:
> > Add ONE_REG support for AltiVec on Book3E.
> >
> > Signed-off-by: Mihai Caraman <mihai.caraman at freescale.com>
> > ---
> >  arch/powerpc/kvm/booke.c |   32 ++++++++++++++++++++++++++++++++
> >  1 files changed, 32 insertions(+), 0 deletions(-)
> >
> > diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
> > index 01eb635..019496d 100644
> > --- a/arch/powerpc/kvm/booke.c
> > +++ b/arch/powerpc/kvm/booke.c
> > @@ -1570,6 +1570,22 @@ int kvm_vcpu_ioctl_get_one_reg(struct kvm_vcpu
> > *vcpu, struct kvm_one_reg *reg)
> >  	case KVM_REG_PPC_DEBUG_INST:
> >  		val = get_reg_val(reg->id, KVMPPC_INST_EHPRIV);
> >  		break;
> > +#ifdef CONFIG_ALTIVEC
> > +	case KVM_REG_PPC_VR0 ... KVM_REG_PPC_VR31:
> > +		if (!cpu_has_feature(CPU_FTR_ALTIVEC)) {
> > +			r = -ENXIO;
> > +			break;
> > +		}
> > +		val.vval = vcpu->arch.vr[reg->id - KVM_REG_PPC_VR0];
> > +		break;
> > +	case KVM_REG_PPC_VSCR:
> > +		if (!cpu_has_feature(CPU_FTR_ALTIVEC)) {
> > +			r = -ENXIO;
> > +			break;
> > +		}
> > +		val = get_reg_val(reg->id, vcpu->arch.vscr.u[3]);
> > +		break;
> 
> Why u[3]?

AltiVec PEM manual says: "The VSCR has two defined bits, the AltiVec non-Java
mode (NJ) bit (VSCR[15]) and the AltiVec saturation (SAT) bit (VSCR[31]);
the remaining bits are reserved."

I think this is the reason Paul M. exposed KVM_REG_PPC_VSCR width as 32-bit.

-Mike