Re: [PATCH v5 2/5] KVM: arm64: Add PSCI v1.3 SYSTEM_OFF2 function for hibernation

[Oliver Upton]

Hi David,

On Thu, Sep 26, 2024 at 07:37:57PM +0100, David Woodhouse wrote:
> @@ -392,6 +403,32 @@ static int kvm_psci_1_x_call(struct kvm_vcpu *vcpu, u32 minor)
>  			break;
>  		}
>  		break;
> +	case PSCI_1_3_FN_SYSTEM_OFF2:
> +		kvm_psci_narrow_to_32bit(vcpu);
> +		fallthrough;
> +	case PSCI_1_3_FN64_SYSTEM_OFF2:
> +		if (minor < 3)
> +			break;
> +
> +		arg = smccc_get_arg1(vcpu);
> +		if (arg != PSCI_1_3_HIBERNATE_TYPE_OFF) {
> +			val = PSCI_RET_INVALID_PARAMS;
> +			break;
> +		}

This is missing a check that arg2 must be zero.

> +		kvm_psci_system_off2(vcpu);
> +		/*
> +		 * We shouldn't be going back to guest VCPU after
> +		 * receiving SYSTEM_OFF2 request.
> +		 *
> +		 * If user space accidentally/deliberately resumes
> +		 * guest VCPU after SYSTEM_OFF2 request then guest
> +		 * VCPU should see internal failure from PSCI return
> +		 * value. To achieve this, we preload r0 (or x0) with
> +		 * PSCI return value INTERNAL_FAILURE.
> +		 */
> +		val = PSCI_RET_INTERNAL_FAILURE;
> +		ret = 0;
> +		break;
>  	default:
>  		return kvm_psci_0_2_call(vcpu);
>  	}
> -- 
> 2.44.0
>

-- 
Thanks,
Oliver