linux-kernel - Re: [PATCH v4 18/43] arm64: RME: Handle realm enter/exit

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Message-ID: <yq5a34mx2of7.fsf@kernel.org>
Date: Thu, 22 Aug 2024 09:34:44 +0530
From: Aneesh Kumar K.V <aneesh.kumar@...nel.org>
To: Steven Price <steven.price@....com>, kvm@...r.kernel.org,
	kvmarm@...ts.linux.dev
Cc: Steven Price <steven.price@....com>,
	Catalin Marinas <catalin.marinas@....com>,
	Marc Zyngier <maz@...nel.org>, Will Deacon <will@...nel.org>,
	James Morse <james.morse@....com>,
	Oliver Upton <oliver.upton@...ux.dev>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	Zenghui Yu <yuzenghui@...wei.com>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Joey Gouly <joey.gouly@....com>,
	Alexandru Elisei <alexandru.elisei@....com>,
	Christoffer Dall <christoffer.dall@....com>,
	Fuad Tabba <tabba@...gle.com>, linux-coco@...ts.linux.dev,
	Ganapatrao Kulkarni <gankulkarni@...amperecomputing.com>,
	Gavin Shan <gshan@...hat.com>,
	Shanker Donthineni <sdonthineni@...dia.com>,
	Alper Gun <alpergun@...gle.com>
Subject: Re: [PATCH v4 18/43] arm64: RME: Handle realm enter/exit

Steven Price <steven.price@....com> writes:

....

> +static int rec_exit_ripas_change(struct kvm_vcpu *vcpu)
> +{
> +	struct kvm *kvm = vcpu->kvm;
> +	struct realm *realm = &kvm->arch.realm;
> +	struct realm_rec *rec = &vcpu->arch.rec;
> +	unsigned long base = rec->run->exit.ripas_base;
> +	unsigned long top = rec->run->exit.ripas_top;
> +	unsigned long ripas = rec->run->exit.ripas_value & 1;
> +	unsigned long top_ipa;
> +	int ret = -EINVAL;
> +
> +	if (realm_is_addr_protected(realm, base) &&
> +	    realm_is_addr_protected(realm, top - 1)) {
> +		kvm_mmu_topup_memory_cache(&vcpu->arch.mmu_page_cache,
> +					   kvm_mmu_cache_min_pages(vcpu->arch.hw_mmu));
> +		write_lock(&kvm->mmu_lock);
> +		ret = realm_set_ipa_state(vcpu, base, top, ripas, &top_ipa);
> +		write_unlock(&kvm->mmu_lock);
> +	}
> +
> +	WARN(ret && ret != -ENOMEM,
> +	     "Unable to satisfy SET_IPAS for %#lx - %#lx, ripas: %#lx\n",
> +	     base, top, ripas);
> +
> +	/* Exit to VMM to complete the change */
> +	kvm_prepare_memory_fault_exit(vcpu, base, top_ipa - base, false, false,
> +				      ripas == 1);
> +
> +	return 0;
> +}
> +

arch/arm64/kvm/rme-exit.c:100:6: warning: variable 'top_ipa' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
        if (realm_is_addr_protected(realm, base) &&
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
arch/arm64/kvm/rme-exit.c:114:44: note: uninitialized use occurs here
        kvm_prepare_memory_fault_exit(vcpu, base, top_ipa - base, false, false,
                                                  ^~~~~~~

-aneesh