Subject: [PATCH 1/6] ARM: kvm: psci: fix handling of unimplemented functions

From: [email-masked] (Marc Zyngier)
Date: Tue, 09 Jun 2015 18:18:20 +0100

Hi Lorenzo,

On 29/05/15 13:16, Lorenzo Pieralisi wrote:
> According to the PSCI specification and the SMC/HVC calling
> convention, PSCI function_ids that are not implemented must
> return NOT_SUPPORTED as return value.
> 
> Current KVM implementation takes an unhandled PSCI function_id
> as an error and injects an undefined instruction into the guest
> if PSCI implementation is called with a function_id that is not
> handled by the resident PSCI version (ie it is not implemented),
> which is not the behaviour expected by a guest when calling a
> PSCI function_id that is not implemented.
> 
> This patch fixes this issue by returning NOT_SUPPORTED whenever
> the kvm PSCI call is executed for a function_id that is not
> implemented by the PSCI kvm layer.
> 
> Signed-off-by: Lorenzo Pieralisi <[email-masked]>
> Reported-by: Sudeep Holla <[email-masked]>
> Cc: Christoffer Dall <[email-masked]>
> Cc: Anup Patel <[email-masked]>
> Cc: Marc Zyngier <[email-masked]>
> ---
>  arch/arm/kvm/psci.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm/kvm/psci.c b/arch/arm/kvm/psci.c
> index 7e9398c..ec5943b 100644
> --- a/arch/arm/kvm/psci.c
> +++ b/arch/arm/kvm/psci.c
> @@ -273,7 +273,8 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
>  		ret = 0;
>  		break;
>  	default:
> -		return -EINVAL;
> +		val = PSCI_RET_NOT_SUPPORTED;
> +		break;
>  	}
>  
>  	*vcpu_reg(vcpu, 0) = val;
> @@ -295,10 +296,9 @@ static int kvm_psci_0_1_call(struct kvm_vcpu *vcpu)
>  		break;
>  	case KVM_PSCI_FN_CPU_SUSPEND:
>  	case KVM_PSCI_FN_MIGRATE:
> +	default:
>  		val = PSCI_RET_NOT_SUPPORTED;
>  		break;
> -	default:
> -		return -EINVAL;
>  	}
>  
>  	*vcpu_reg(vcpu, 0) = val;
> 

Looks good to me. How do you want to proceed with this one? can I take
it independently from the rest of the series? Or would you prefer it
being kept as a whole?

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...