linux-kernel - Re: [PATCH v3 2/9] s390: ap: kvm: setting a hook for PQAP instructions

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Message-Id: <336a22e1-5b42-5dd8-f771-e417bda05342@linux.ibm.com>
Date:   Fri, 15 Feb 2019 10:55:57 +0100
From:   Pierre Morel <pmorel@...ux.ibm.com>
To:     Cornelia Huck <cohuck@...hat.com>
Cc:     borntraeger@...ibm.com, alex.williamson@...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, david@...hat.com, schwidefsky@...ibm.com,
        heiko.carstens@...ibm.com, freude@...ux.ibm.com, mimu@...ux.ibm.com
Subject: Re: [PATCH v3 2/9] s390: ap: kvm: setting a hook for PQAP
 instructions

On 15/02/2019 10:26, Cornelia Huck wrote:
> On Thu, 14 Feb 2019 17:45:06 +0100
> Pierre Morel <pmorel@...ux.ibm.com> wrote:
> 
>> On 14/02/2019 16:54, Cornelia Huck wrote:
>>> On Thu, 14 Feb 2019 14:51:02 +0100
>>> Pierre Morel <pmorel@...ux.ibm.com> wrote:
>>>    
>>>> This patch adds interception code for the PQAP instructions,
>>>> and a callback inside the KVM arch structure for s390.
>>>>
>>>> If a VFIO-AP drivers needs to intercept PQAP/AQIC or PQAP/TAPQ
>>>
>>> s/drivers/driver/
>>
>> thanks. OK
>>
> 
>>>> + *
>>>> + * This callback only handles PQAP/AQIC instruction and
>>>
>>> Here you only talk about PQAP/AQIC, what about PQAP/TAPQ mentioned in
>>> the patch description?
>>
>> I can add "for now" or "in this patch" or suppress the reference to
>> PAPQ/TAPQ
> 
> I'd just add a note to the patch description that this patch only
> handles PQAP/AQCI and that handling PQAP/TAPQ is something for a
> follow-on patch.

OK, I will clear this.
Thanks


> 
>>
>>>   

...snip...

>>>> +	/* PQAP instructions are allowed for guest kernel only */
>>>> +	if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE)
>>>> +		return kvm_s390_inject_program_int(vcpu, PGM_PRIVILEGED_OP);
>>>> +	/* AQIC instruction is allowed only if facility 65 is available */
>>>> +	if (!test_kvm_facility(vcpu->kvm, 65))
>>>> +		return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
>>>> +	/* All right, call the callback */
>>>> +	return vcpu->kvm->arch.crypto.pqap_hook(vcpu);
>>>
>>> Can that callback also return -EOPNOTSUPP to order to drop to user
>>> space?
>>
>> Yes.
>> Why not?
> 
> Maybe also mention that in the function description?
> 

Will do thanks.

Regards,
Pierre

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