[PATCH 2/2] powerpc/kvm: Update kvmppc_set_arch_compat() for ISA v3.00

[Michael Ellerman]

Suraj Jitindar Singh <sjitindarsingh at gmail.com> writes:
> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
> index 3686471..f9ae3fb 100644
> --- a/arch/powerpc/kvm/book3s_hv.c
> +++ b/arch/powerpc/kvm/book3s_hv.c
> @@ -311,24 +311,38 @@ static int kvmppc_set_arch_compat(struct kvm_vcpu *vcpu, u32 arch_compat)
>  			 * If an arch bit is set in PCR, all the defined
>  			 * higher-order arch bits also have to be set.
>  			 */
> -			pcr = PCR_ARCH_206 | PCR_ARCH_205;
> +			pcr = PCR_ARCH_207 | PCR_ARCH_206 | PCR_ARCH_205;
>  			break;
>  		case PVR_ARCH_206:
>  		case PVR_ARCH_206p:
> -			pcr = PCR_ARCH_206;
> +			/* Must be at least v2.06 to emulate it */
> +			if (!cpu_has_feature(CPU_FTR_ARCH_206))
> +				return -EINVAL;
> +			pcr = PCR_ARCH_207 | PCR_ARCH_206;
>  			break;
>  		case PVR_ARCH_207:
> +			/* Must be at least v2.07 to emulate it */
> +			if (!cpu_has_feature(CPU_FTR_ARCH_207S))
> +				return -EINVAL;
> +			pcr = PCR_ARCH_207;
>  			break;
> +		case PVR_ARCH_300:
> +			/* Must be at least v3.00 to emulate it */
> +			if (!cpu_has_feature(CPU_FTR_ARCH_300))
> +				return -EINVAL;
>  		default:
>  			return -EINVAL;
>  		}
>  
> -		if (!cpu_has_feature(CPU_FTR_ARCH_207S)) {
> -			/* POWER7 can't emulate POWER8 */
> -			if (!(pcr & PCR_ARCH_206))
> -				return -EINVAL;
> -			pcr &= ~PCR_ARCH_206;
> -		}
> +		/*
> +		 * Mask the pcr bits which the current processor knows about
> +		 * v2.06 and above knows about the v2.05 compat bit
> +		 * v2,07 and above knows about the v2.06 compat bit
> +		 * v3.00 and above knows about the v2.07 compat bit
> +		 */
> +		pcr &= (cpu_has_feature(CPU_FTR_ARCH_300) << 3) |
> +			(cpu_has_feature(CPU_FTR_ARCH_207S) << 2) |
> +			(cpu_has_feature(CPU_FTR_ARCH_206) << 1);

cpu_has_feature() returns a bool, so shifting the result of it is
dubious. It also uses jump labels these days, so I have no idea what
code that is going to generate.

Better to just do it the simple way IMHO.

cheers