linux-kernel - Re: [PATCH v2 4/5] KVM: s390: vsie: Always test the crycbd for NULL

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Message-Id: <b1d0862e-3bf2-bfb4-8926-e8876b7fdb72@linux.ibm.com>
Date:   Thu, 23 Aug 2018 08:57:12 +0200
From:   Pierre Morel <pmorel@...ux.ibm.com>
To:     David Hildenbrand <david@...hat.com>
Cc:     linux-kernel@...r.kernel.org, cohuck@...hat.com,
        linux-s390@...r.kernel.org, kvm@...r.kernel.org,
        frankja@...ux.ibm.com, akrowiak@...ux.ibm.com,
        borntraeger@...ibm.com, schwidefsky@...ibm.com,
        heiko.carstens@...ibm.com
Subject: Re: [PATCH v2 4/5] KVM: s390: vsie: Always test the crycbd for NULL

On 22/08/2018 19:07, David Hildenbrand wrote:
> On 22.08.2018 18:51, Pierre Morel wrote:
>> BUG: the crycbd must be tested for null even if
>> not crossing a page boundary (which will never
>> occur in this case anyway).
> 
> I don't see the BUG. Can you elaborate? (maybe it is too late for me)

No it was too late for me :)
The BUG was by me, my brain was fooled by the "else"
there is not problem there.
CRCBD is always tested.

Sorry.

> 
> Either we return or we check for !crycb_addr
> 
>>
>> Signed-off-by: Pierre Morel <pmorel@...ux.ibm.com>
>> ---
>>   arch/s390/kvm/vsie.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
>> index 0b12916..7ee4329 100644
>> --- a/arch/s390/kvm/vsie.c
>> +++ b/arch/s390/kvm/vsie.c
>> @@ -172,7 +172,7 @@ static int shadow_crycb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
>>   
>>   	if ((crycb_addr & PAGE_MASK) != ((crycb_addr + 128) & PAGE_MASK))
>>   		return set_validity_icpt(scb_s, 0x003CU);
>> -	else if (!crycb_addr)
>> +	if (!crycb_addr)
>>   		return set_validity_icpt(scb_s, 0x0039U);
>>   
>>   	/* copy only the wrapping keys */
>>
> 
> 


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