[PATCH V2] arm64: KVM: Support X-Gene guest VCPU on APM X-Gene host

[Mark Rutland]

On Tue, Jul 16, 2013 at 07:55:34AM +0100, Anup Patel wrote:
> This patch allows us to have X-Gene guest VCPU when using KVM arm64
> on APM X-Gene host.
> 
> We add KVM_ARM_TARGET_XGENE_POTENZA for X-Gene Potenza compatible
> guest VCPU and we return KVM_ARM_TARGET_XGENE_POTENZA in kvm_target_cpu()
> when running on X-Gene host with Potenza core.
> 
> V2:
>  - Renamed KVM_ARM_TARGET_XGENE_V8 to KVM_ARM_TARGET_XGENE_POTENZA
> 
> V1:
>  - Initial patch with target named as KVM_ARM_TARGET_XGENE_V8
> 
> Signed-off-by: Anup Patel <anup.patel at linaro.org>
> Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar at linaro.org>
> ---
>  arch/arm64/include/uapi/asm/kvm.h    |    3 ++-
>  arch/arm64/kvm/guest.c               |   34 ++++++++++++++++++++++------------
>  arch/arm64/kvm/sys_regs_generic_v8.c |    3 +++
>  3 files changed, 27 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
> index 5031f42..d9f026b 100644
> --- a/arch/arm64/include/uapi/asm/kvm.h
> +++ b/arch/arm64/include/uapi/asm/kvm.h
> @@ -55,8 +55,9 @@ struct kvm_regs {
>  #define KVM_ARM_TARGET_AEM_V8		0
>  #define KVM_ARM_TARGET_FOUNDATION_V8	1
>  #define KVM_ARM_TARGET_CORTEX_A57	2
> +#define KVM_ARM_TARGET_XGENE_POTENZA	3
>  
> -#define KVM_ARM_NUM_TARGETS		3
> +#define KVM_ARM_NUM_TARGETS		4
>  
>  /* KVM_ARM_SET_DEVICE_ADDR ioctl id encoding */
>  #define KVM_ARM_DEVICE_TYPE_SHIFT	0
> diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
> index 2c3ff67..a466244 100644
> --- a/arch/arm64/kvm/guest.c
> +++ b/arch/arm64/kvm/guest.c
> @@ -207,19 +207,29 @@ int __attribute_const__ kvm_target_cpu(void)
>  	unsigned long implementor = read_cpuid_implementor();
>  	unsigned long part_number = read_cpuid_part_number();
>  
> -	if (implementor != ARM_CPU_IMP_ARM)
> -		return -EINVAL;
> -
> -	switch (part_number) {
> -	case ARM_CPU_PART_AEM_V8:
> -		return KVM_ARM_TARGET_AEM_V8;
> -	case ARM_CPU_PART_FOUNDATION:
> -		return KVM_ARM_TARGET_FOUNDATION_V8;
> -	case ARM_CPU_PART_CORTEX_A57:
> -		/* Currently handled by the generic backend */
> -		return KVM_ARM_TARGET_CORTEX_A57;
> +	switch (implementor) {
> +	case ARM_CPU_IMP_ARM:
> +		switch (part_number) {
> +		case ARM_CPU_PART_AEM_V8:
> +			return KVM_ARM_TARGET_AEM_V8;
> +		case ARM_CPU_PART_FOUNDATION:
> +			return KVM_ARM_TARGET_FOUNDATION_V8;
> +		case ARM_CPU_PART_CORTEX_A57:
> +			return KVM_ARM_TARGET_CORTEX_A57;
> +		default:
> +			return -EINVAL;
> +		}
> +		break;
> +	case ARM_CPU_IMP_APM:
> +		switch (part_number) {
> +		case APM_CPU_PART_POTENZA:
> +			return KVM_ARM_TARGET_XGENE_POTENZA;
> +		default:
> +			return -EINVAL;
> +		}
> +		break;
>  	default:
> -		return -EINVAL;
> + 		return -EINVAL;
>  	}

Why not place a return -EINVAL here, outside of the outer switch
statement? That way you don't need to duplicate it for an unknown
implementor or a known implementor's unknown CPU, as long as you keep
the break at the end of each implementor's case.

Thanks,
Mark.

>  }
>  
> diff --git a/arch/arm64/kvm/sys_regs_generic_v8.c b/arch/arm64/kvm/sys_regs_generic_v8.c
> index 4268ab9..8fe6f76 100644
> --- a/arch/arm64/kvm/sys_regs_generic_v8.c
> +++ b/arch/arm64/kvm/sys_regs_generic_v8.c
> @@ -90,6 +90,9 @@ static int __init sys_reg_genericv8_init(void)
>  					  &genericv8_target_table);
>  	kvm_register_target_sys_reg_table(KVM_ARM_TARGET_CORTEX_A57,
>  					  &genericv8_target_table);
> +	kvm_register_target_sys_reg_table(KVM_ARM_TARGET_XGENE_POTENZA,
> +					  &genericv8_target_table);
> +
>  	return 0;
>  }
>  late_initcall(sys_reg_genericv8_init);
> -- 
> 1.7.9.5
> 
> 
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