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

[Paul Mackerras <paulus@ozlabs.org>]

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;

Paul.