linux-kernel - Re: [PATCH v1] KVM: s390: vsie: fix Do the CRYCB validation first

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Date:   Fri, 1 Feb 2019 14:36:07 +0100
From:   Pierre Morel <pmorel@...ux.ibm.com>
To:     Cornelia Huck <cohuck@...hat.com>
Cc:     borntraeger@...ibm.com, david@...hat.com,
        linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org,
        kvm@...r.kernel.org, frankja@...ux.ibm.com, akrowiak@...ux.ibm.com,
        pasic@...ux.ibm.com
Subject: Re: [PATCH v1] KVM: s390: vsie: fix Do the CRYCB validation first

On 01/02/2019 11:50, Cornelia Huck wrote:
> On Fri,  1 Feb 2019 10:52:05 +0100
> Pierre Morel <pmorel@...ux.ibm.com> wrote:
> 
>> The case when the SIE for guest3 is not setup for using
>> encryption keys nor Adjunct processor but the guest2
>> does use these features was not properly handled.
>>
>> This leads SIE entry for guest3 to crash with validity intercept
>> because the guest2, not having the use of encryption keys nor
>> Adjunct Processor did not initialize the CRYCB designation.
>>
>> In the case where none of ECA_APIE, ECB3_AES or ECB3_DEA
>> are set in guest3 a format 0 CRYCB is allowed for guest3
>> and the CRYCB designation in the SIE for guest3 is not checked
>> on SIE entry.
>>
>> Let's allow the CRYCD designation to be ignored when the
> 
> s/CRYCD/CRYCB/
> 
>> SIE for guest3 is not initialized for encryption key usage
>> nor AP.
>>
>> Fixup: d6f6959 (KVM: s390: vsie: Do the CRYCB validation first)
> 
> I think the canonical format is
> 
> Fixes: d6f6959ac587 ("KVM: s390: vsie: Do the CRYCB validation first")
> 
>>
> 
> CC: stable@...r.kernel.org # 4.20+
> 
>> Signed-off-by: Pierre Morel <pmorel@...ux.ibm.com>
>> Reported-by: Claudio Imbrenda <imbrenda@...ux.ibm.com>
>> ---
>>   arch/s390/kvm/vsie.c | 3 +++
>>   1 file changed, 3 insertions(+)
>>
>> diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
>> index a153257..a748f76 100644
>> --- a/arch/s390/kvm/vsie.c
>> +++ b/arch/s390/kvm/vsie.c
>> @@ -300,6 +300,9 @@ static int shadow_crycb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
>>   	if (!apie_h && !key_msk)
>>   		return 0;
>>   
>> +	if (!(scb_o->eca & ECA_APIE) && !(scb_o->ecb3 & (ECB3_AES | ECB3_DEA)))
>> +		return 0;
>> +
>>   	if (!crycb_addr)
>>   		return set_validity_icpt(scb_s, 0x0039U);
>>   
> 
> Looks sane to me, but I'll let vsie experts comment.
> 

Thanks
Pierre

-- 
Pierre Morel
Linux/KVM/QEMU in Böblingen - Germany