[PATCH v4 18/43] arm64: RME: Handle realm enter/exit

[Steven Price]

On 22/08/2024 05:04, Aneesh Kumar K.V wrote:
> Steven Price <steven.price at arm.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,
>                                                   ^~~~~~~

I'm not sure why I didn't notice this before, if the condition is false
then we're hitting the WARN (i.e. this shouldn't happen), but I should
fix that up to handle the situation better.

Steve