linux-kernel - Re: [PATCH v5 2/5] KVM: arm64: Add PSCI v1.3 SYSTEM

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Message-ID: <ZvwUK34LYeGuBV2H@linux.dev>
Date: Tue, 1 Oct 2024 08:24:27 -0700
From: Oliver Upton <oliver.upton@...ux.dev>
To: David Woodhouse <dwmw2@...radead.org>
Cc: Paolo Bonzini <pbonzini@...hat.com>, Jonathan Corbet <corbet@....net>,
	Marc Zyngier <maz@...nel.org>, James Morse <james.morse@....com>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	Zenghui Yu <yuzenghui@...wei.com>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>, Mark Rutland <mark.rutland@....com>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Pavel Machek <pavel@....cz>, Len Brown <len.brown@...el.com>,
	Shuah Khan <shuah@...nel.org>, David Woodhouse <dwmw@...zon.co.uk>,
	kvm@...r.kernel.org, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	kvmarm@...ts.linux.dev, linux-pm@...r.kernel.org,
	linux-kselftest@...r.kernel.org,
	Francesco Lavra <francescolavra.fl@...il.com>,
	Miguel Luis <miguel.luis@...cle.com>
Subject: Re: [PATCH v5 2/5] KVM: arm64: Add PSCI v1.3 SYSTEM_OFF2 function
 for hibernation

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