Re: [PATCH v2 07/10] KVM: PPC: reimplement LOAD_FP/STORE_FP instruction mmio emulation with analyse_intr() input

[Simon Guo <wei.guo.simon@gmail.com>]

On Thu, May 17, 2018 at 09:52:07AM +1000, Paul Mackerras wrote:
> On Mon, May 07, 2018 at 02:20:13PM +0800, wei.guo.simon@gmail.com wrote:
> > From: Simon Guo <wei.guo.simon@gmail.com>
> > 
> > This patch reimplements LOAD_FP/STORE_FP instruction MMIO emulation with
> > analyse_intr() input. It utilizes the FPCONV/UPDATE properties exported by
> > analyse_instr() and invokes kvmppc_handle_load(s)/kvmppc_handle_store()
> > accordingly.
> > 
> > For FP store MMIO emulation, the FP regs need to be flushed firstly so
> > that the right FP reg vals can be read from vcpu->arch.fpr, which will
> > be stored into MMIO data.
> > 
> > Suggested-by: Paul Mackerras <paulus@ozlabs.org>
> > Signed-off-by: Simon Guo <wei.guo.simon@gmail.com>
> 
> One comment below, otherwise looks good...
> 
> >  arch/powerpc/kvm/emulate_loadstore.c | 197 +++++++----------------------------
> >  1 file changed, 40 insertions(+), 157 deletions(-)
> > 
> > diff --git a/arch/powerpc/kvm/emulate_loadstore.c b/arch/powerpc/kvm/emulate_loadstore.c
> > index 2a91845..5a6571c 100644
> > --- a/arch/powerpc/kvm/emulate_loadstore.c
> > +++ b/arch/powerpc/kvm/emulate_loadstore.c
> > @@ -138,6 +138,22 @@ int kvmppc_emulate_loadstore(struct kvm_vcpu *vcpu)
> >  
> >  			break;
> >  		}
> > +#ifdef CONFIG_PPC_FPU
> > +		case LOAD_FP:
> > +			if (kvmppc_check_fp_disabled(vcpu))
> > +				return EMULATE_DONE;
> > +
> > +			if (op.type & FPCONV)
> > +				vcpu->arch.mmio_sp64_extend = 1;
> > +
> > +			emulated = kvmppc_handle_load(run, vcpu,
> > +					KVM_MMIO_REG_FPR|op.reg, size, 1);
> 
> You need to check the SIGNEXT flag and call kvmppc_handle_loads if it
> is set, because of the lfiwax case:
> 
> > -		case OP_31_XOP_LFIWAX:
> > -			if (kvmppc_check_fp_disabled(vcpu))
> > -				return EMULATE_DONE;
> > -			emulated = kvmppc_handle_loads(run, vcpu,
> > -				KVM_MMIO_REG_FPR|rt, 4, 1);
> > -			break;

Yes. I need to handle that. Thanks for point it out.

BR,
 - Simon