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

Anthony Krowiak
2025-02-26T14:16:48Z

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@linux.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)