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 11:04:22 +0100
From:   Cornelia Huck <cohuck@...hat.com>
To:     Pierre Morel <pmorel@...ux.ibm.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 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 assume you'll have similar code even when using a different
interface.]

> +	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 :)

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