From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pierre Morel Subject: Re: [PATCH v1 4/7] vfio: ap: AP Queue Interrupt Control VFIO ioctl calls Date: Thu, 8 Nov 2018 19:00:37 +0100 Message-ID: <29392872-d8a0-3ddd-77fe-342202ed1d2a@linux.ibm.com> References: <1541009577-29656-1-git-send-email-pmorel@linux.ibm.com> <1541009577-29656-5-git-send-email-pmorel@linux.ibm.com> <20181107104624.36707cca.cohuck@redhat.com> <97094e1c-f74c-7b90-8439-5177301d3189@linux.ibm.com> <20181108101435.023e835d.cohuck@redhat.com> Reply-To: pmorel@linux.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format="flowed" Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20181108101435.023e835d.cohuck@redhat.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Archive: List-Post: To: Cornelia Huck 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 List-ID: On 08/11/2018 10:14, Cornelia Huck wrote: > On Wed, 7 Nov 2018 23:23:40 +0100 > Pierre Morel wrote: > >> On 07/11/2018 10:46, Cornelia Huck wrote: >>> On Wed, 31 Oct 2018 19:12:54 +0100 >>> Pierre Morel 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 >>>> --- >>>> 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