From: Pierre Morel <pmorel@linux.ibm.com>
To: Cornelia Huck <cohuck@redhat.com>
Cc: borntraeger@de.ibm.com, alex.williamson@redhat.com,
linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org,
kvm@vger.kernel.org, frankja@linux.ibm.com,
akrowiak@linux.ibm.com, pasic@linux.ibm.com, david@redhat.com,
schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com,
freude@linux.ibm.com, mimu@linux.ibm.com
Subject: Re: [PATCH v1 4/7] vfio: ap: AP Queue Interrupt Control VFIO ioctl calls
Date: Thu, 8 Nov 2018 19:00:37 +0100 [thread overview]
Message-ID: <29392872-d8a0-3ddd-77fe-342202ed1d2a@linux.ibm.com> (raw)
In-Reply-To: <20181108101435.023e835d.cohuck@redhat.com>
On 08/11/2018 10:14, Cornelia Huck wrote:
> On Wed, 7 Nov 2018 23:23:40 +0100
> Pierre Morel <pmorel@linux.ibm.com> wrote:
>
>> On 07/11/2018 10:46, Cornelia Huck wrote:
>>> On Wed, 31 Oct 2018 19:12:54 +0100
>>> Pierre Morel <pmorel@linux.ibm.com> wrote:
>>>
>>>> This is the implementation of the VFIO ioctl calls to handle
>>>> the AQIC interception and use GISA to handle interrupts.
>>>>
>>>> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
>>>> ---
>>>> drivers/s390/crypto/vfio_ap_ops.c | 95 +++++++++++++++++++++++++++++++
>>>> 1 file changed, 95 insertions(+)
>>>>
>>>> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
>>>> index 272ef427dcc0..f68102163bf4 100644
>>>> --- a/drivers/s390/crypto/vfio_ap_ops.c
>>>> +++ b/drivers/s390/crypto/vfio_ap_ops.c
>>>> @@ -895,12 +895,107 @@ static int vfio_ap_mdev_get_device_info(unsigned long arg)
>>>> return copy_to_user((void __user *)arg, &info, minsz);
>>>> }
>>>>
>>>> +static int ap_ioctl_setirq(struct ap_matrix_mdev *matrix_mdev,
>>>> + struct vfio_ap_aqic *parm)
>>>> +{
>>>> + struct aqic_gisa aqic_gisa = reg2aqic(0);
>>>> + struct kvm_s390_gisa *gisa = matrix_mdev->kvm->arch.gisa;
>>>> + struct ap_status ap_status = reg2status(0);
>>>> + unsigned long p;
>>>> + int ret = -1;
>>>> + int apqn;
>>>> + uint32_t gd;
>>>> +
>>>> + apqn = (int)(parm->cmd & 0xffff);
>>>
>>> It seems you always use cmd & 0xffff only. What if there is other stuff
>>> in the remaining bits of cmd? Do you plan to ignore it in any case, or
>>> should you actively check that there is nothing in it?
>>>
>>
>> I do not think that the ioctl interface should reflect the hardware
>> interface.
>> The ioctl interface ignores the remaining bits.
>> We ignore the FC because we obviously want to make a AQIC FC=3
>> We ignore the T bit.
>>
>> But we receive the information from the intercepting software, i.e. QEMU
>> which should I think do the checks before using the ioctl interface.
>
> Yes, it should; but you still can't know whether it actually did...
I do not care, I just ignore these bits.
>
>>
>> It seemed easier to me to pass the complete registers and to ignore some
>> bits in them. In case we get any change in the future
>> But we could also only pass the APQN
>
> I'd prefer to use a well-defined structure that explicitly handles the
> userspace<->kernel communication. Not that we start relying on implicit
> assumptions and then things break when userspace does something
> different...
>
OK, I can pass a u16 in the ioctl parameters and explicitly reserve the
ignored bits.
Thanks for the review.
Regards,
Pierre
--
Pierre Morel
Linux/KVM/QEMU in Böblingen - Germany
next prev parent reply other threads:[~2018-11-08 18:00 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-31 18:12 [PATCH v1 0/7] s390: vfio: ap: Using GISA for AP Interrupt Pierre Morel
2018-10-31 18:12 ` [PATCH v1 1/7] vfio: ap: Add AP Queue Interruption Control facility Pierre Morel
2018-11-02 14:45 ` Tony Krowiak
2018-10-31 18:12 ` [PATCH v1 2/7] vfio: ap: VFIO AP Queue Interrupt Control Pierre Morel
2018-10-31 18:12 ` [PATCH v1 3/7] vfio: ap: AP Queue Interrupt structures definitions Pierre Morel
2018-11-02 15:14 ` Tony Krowiak
2018-11-05 8:46 ` Pierre Morel
2018-10-31 18:12 ` [PATCH v1 4/7] vfio: ap: AP Queue Interrupt Control VFIO ioctl calls Pierre Morel
2018-11-02 3:51 ` kbuild test robot
2018-11-06 20:21 ` Tony Krowiak
2018-11-07 22:31 ` Pierre Morel
2018-11-13 15:40 ` Tony Krowiak
2018-11-07 9:46 ` Cornelia Huck
2018-11-07 22:23 ` Pierre Morel
2018-11-08 9:14 ` Cornelia Huck
2018-11-08 18:00 ` Pierre Morel [this message]
2018-10-31 18:12 ` [PATCH v1 5/7] s390: kvm: export GIB registration Pierre Morel
2018-10-31 18:12 ` [PATCH v1 6/7] vfio: ap: register guest ISC with GISA and GIB Pierre Morel
2018-11-02 5:49 ` kbuild test robot
2018-11-06 20:21 ` Tony Krowiak
2018-11-07 22:40 ` Pierre Morel
2018-10-31 18:12 ` [PATCH v1 7/7] s390: kvm: Handle all GISA IPM bits through GISA Pierre Morel
2018-11-06 12:07 ` David Hildenbrand
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