linux-kernel - Re: [PATCH v2 3/3] vfio: ap: AP Queue Interrupt Control VFIO ioctl calls

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Date:   Mon, 3 Dec 2018 11:20:33 +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 v2 3/3] vfio: ap: AP Queue Interrupt Control VFIO ioctl
 calls

On 03/12/2018 11:04, Cornelia Huck wrote:
> On Thu, 22 Nov 2018 18:11:15 +0100
> Pierre Morel <pmorel@...ux.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@...ux.ibm.com>
>> ---
>>   drivers/s390/crypto/vfio_ap_ops.c | 110 +++++++++++++++++++++++++++++++++++++-
>>   1 file changed, 109 insertions(+), 1 deletion(-)
>>
> 
>> +static int vfio_ap_ioctl_setirq(struct mdev_device *mdev, unsigned long arg)
>> +{
>> +	struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
>> +	struct vfio_ap_aqic parm;
>> +	struct ap_qirq_ctrl aqic_gisa = {};
>> +	struct kvm *kvm = matrix_mdev->kvm;
>> +	struct kvm_s390_gisa *gisa = kvm->arch.gisa;
>> +	struct ap_queue_status ap_status;
>> +	unsigned long nib;
>> +
>> +	if (copy_from_user(&parm, (void __user *)arg, sizeof(parm)))
>> +		return -EFAULT;
>> +
>> +	if (parm.isc > MAX_ISC)
>> +		return -EINVAL;
>> +
>> +	if (kvm->vcpus[0]->arch.sie_block->gd & 0x01)
>> +		aqic_gisa.gf = 1;
>> +
>> +	nib = vfio_ap_get_nib(kvm, &parm);
>> +	if (!nib)
>> +		return -ENODEV;
>> +
>> +	aqic_gisa.gisc = parm.isc;
>> +	aqic_gisa.isc = kvm_s390_gisc_register(kvm, parm.isc);
> 
> Oh, and as I just looked at the callers of these functions: You'll want
> to check the return code here, even though the function should not fail
> with the checking you did beforehand.
> 

I should check.

> [I assume you'll have similar code even when using a different
> interface.]

Yes.


> 
>> +	aqic_gisa.ir = 1;
>> +	aqic_gisa.gisa = gisa->next_alert >> 4;
>> +
>> +	ap_status = ap_aqic(parm.apqn, aqic_gisa, (void *)nib);
>> +	parm.status = *(uint32_t *)(&ap_status);
>> +
>> +	if (copy_to_user((void __user *)arg, &parm, sizeof(parm))) {
>> +		kvm_s390_gisc_unregister(kvm, parm.isc);
>> +		return -EFAULT;
>> +	}
>> +
>> +	if (ap_status.response_code) {
>> +		kvm_s390_gisc_unregister(kvm, parm.isc);
>> +		return -EIO;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static int vfio_ap_ioctl_clrirq(struct mdev_device *mdev, unsigned long arg)
>> +{
>> +	struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
>> +	struct vfio_ap_aqic parm;
>> +	struct ap_qirq_ctrl aqic_gisa = {};
>> +	struct ap_queue_status ap_status;
>> +	struct kvm *kvm = matrix_mdev->kvm;
>> +
>> +	if (copy_from_user(&parm, (void __user *)arg, sizeof(parm)))
>> +		return -EFAULT;
>> +
>> +	if (kvm->vcpus[0]->arch.sie_block->gd & 0x01)
>> +		aqic_gisa.gf = 1;
>> +	aqic_gisa.ir = 0;
>> +
>> +	ap_status = ap_aqic(parm.apqn, aqic_gisa, NULL);
>> +	parm.status = *(uint32_t *)(&ap_status);
>> +
>> +	kvm_s390_gisc_unregister(kvm, parm.isc);
> 
> Here, you don't seem to verify the sanity of parm.isc beforehand...
> luckily the function can deal with that :)

You are right.
Anyway I will change this, because this relies on user's code which is 
not right.


> 
>> +
>> +	if (copy_to_user((void __user *)arg, &parm, sizeof(parm)))
>> +		return -EFAULT;
>> +
>> +	return (ap_status.response_code) ? -EIO : 0;
>> +}
>> +
> 


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