linux-kernel - Re: [RFC PATCH v2 2/2] s390/vfio-ap: Fixing mdev remove notification

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Message-ID: <86e40763-f76a-4f71-bb50-d1b1a4c77509@linux.ibm.com>
Date: Wed, 26 Feb 2025 09:16:40 -0500
From: Anthony Krowiak <akrowiak@...ux.ibm.com>
To: Rorie Reyes <rreyes@...ux.ibm.com>, linux-s390@...r.kernel.org,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc: hca@...ux.ibm.com, borntraeger@...ibm.com, agordeev@...ux.ibm.com,
        gor@...ux.ibm.com, pasic@...ux.ibm.com, jjherne@...ux.ibm.com,
        alex.williamson@...hat.com
Subject: Re: [RFC PATCH v2 2/2] s390/vfio-ap: Fixing mdev remove notification




On 2/25/25 3:12 PM, Rorie Reyes wrote:
> Removed eventfd from vfio_ap_mdev_unset_kvm
> Update and release locks along with the eventfd added
> to vfio_ap_mdev_request

This patch doesn't really fix anything, it just undoes a line of code 
that was added in
patch 1/2 (see my comment below).

By my reckoning, the purpose for this patch
is to signal an AP config change event to the guest when the crypto 
devices are
removed from the guest's AP configuration as a result of a request to 
remove the
mediated device.


>
> Signed-off-by: Rorie Reyes <rreyes@...ux.ibm.com>
> ---
>   drivers/s390/crypto/vfio_ap_ops.c | 15 ++++++++++++++-
>   1 file changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
> index c6ff4ab13f16..e0237ea27d7e 100644
> --- a/drivers/s390/crypto/vfio_ap_ops.c
> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> @@ -1870,7 +1870,6 @@ static void vfio_ap_mdev_unset_kvm(struct ap_matrix_mdev *matrix_mdev)
>   		get_update_locks_for_kvm(kvm);
>   
>   		kvm_arch_crypto_clear_masks(kvm);
> -		signal_guest_ap_cfg_changed(matrix_mdev);

Why remove a line of code that was added in patch 1/2. Why not just 
rebase patch 1/2 and
remove this line of code from that patch rather than here if it was 
added in error?

>   		vfio_ap_mdev_reset_queues(matrix_mdev);
>   		kvm_put_kvm(kvm);
>   		matrix_mdev->kvm = NULL;
> @@ -2057,6 +2056,14 @@ static void vfio_ap_mdev_request(struct vfio_device *vdev, unsigned int count)
>   
>   	matrix_mdev = container_of(vdev, struct ap_matrix_mdev, vdev);
>   
> +	if (matrix_mdev->kvm) {
> +		get_update_locks_for_kvm(matrix_mdev->kvm);
> +		kvm_arch_crypto_clear_masks(matrix_mdev->kvm);
> +		signal_guest_ap_cfg_changed(matrix_mdev);
> +	} else {
> +		mutex_lock(&matrix_dev->mdevs_lock);
> +	}
> +
>   	if (matrix_mdev->req_trigger) {
>   		if (!(count % 10))
>   			dev_notice_ratelimited(dev,
> @@ -2068,6 +2075,12 @@ static void vfio_ap_mdev_request(struct vfio_device *vdev, unsigned int count)
>   		dev_notice(dev,
>   			   "No device request registered, blocked until released by user\n");
>   	}
> +
> +	if (matrix_mdev->kvm)
> +		release_update_locks_for_kvm(matrix_mdev->kvm);
> +	else
> +		mutex_unlock(&matrix_dev->mdevs_lock);
> +
>   }
>   
>   static int vfio_ap_mdev_get_device_info(unsigned long arg)