Re: [PATCH] s390/vio-ap: Fix no AP queue sharing allowed message written to kernel log

Harald Freudenberger
2025-02-21T07:56:25Z

On 2025-02-20 01:07, Anthony Krowiak wrote:
> An erroneous message is written to the kernel log when either of the
> following actions are taken by a user:
>
> 1. Assign an adapter or domain to a vfio_ap mediated device via its
> sysfs
> assign_adapter or assign_domain attributes that would result in one
> or
> more AP queues being assigned that are already assigned to a
> different
> mediated device. Sharing of queues between mdevs is not allowed.
>
> 2. Reserve an adapter or domain for the host device driver via the AP
> bus
> driver's sysfs apmask or aqmask attribute that would result in
> providing
> host access to an AP queue that is in use by a vfio_ap mediated
> device.
> Reserving a queue for a host driver that is in use by an mdev is not
> allowed.
>
> In both cases, the assignment will return an error; however, a message
> like
> the following is written to the kernel log:
>
> vfio_ap_mdev e1839397-51a0-4e3c-91e0-c3b9c3d3047d: Userspace may not
> re-assign queue 00.0028 already assigned to \
> e1839397-51a0-4e3c-91e0-c3b9c3d3047d
>
> Notice the mdev reporting the error is the same as the mdev identified
> in the message as the one to which the queue is being assigned.
> It is perfectly okay to assign a queue to an mdev to which it is
> already assigned; the assignment is simply ignored by the vfio_ap
> device
> driver.
>
> This patch logs more descriptive and accurate messages for both 1 and 2
> above to the kernel log:
>
> Example for 1:
> vfio_ap_mdev 0fe903a0-a323-44db-9daf-134c68627d61: Userspace may not
> assign
> queue 00.0033 to mdev: already assigned to \
> 62177883-f1bb-47f0-914d-32a22e3a8804
>
> Example for 2:
> vfio_ap_mdev 62177883-f1bb-47f0-914d-32a22e3a8804: Can not reserve
> queue
> 00.0033 for host driver: in use by mdev
>
> Signed-off-by: Anthony Krowiak <akrowiak@linux.ibm.com>
> ---
> drivers/s390/crypto/vfio_ap_ops.c | 73 ++++++++++++++++++++-----------
> 1 file changed, 48 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/s390/crypto/vfio_ap_ops.c
> b/drivers/s390/crypto/vfio_ap_ops.c
> index a52c2690933f..2ce52b491f8a 100644
> --- a/drivers/s390/crypto/vfio_ap_ops.c
> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> @@ -863,48 +863,66 @@ static void vfio_ap_mdev_remove(struct
> mdev_device *mdev)
> vfio_put_device(&matrix_mdev->vdev);
> }
>
> -#define MDEV_SHARING_ERR "Userspace may not re-assign queue
> %02lx.%04lx " \
> - "already assigned to %s"
> +#define MDEV_SHARING_ERR "Userspace may not assign queue %02lx.%04lx "
> \
> + "to mdev: already assigned to %s"
>
> -static void vfio_ap_mdev_log_sharing_err(struct ap_matrix_mdev
> *matrix_mdev,
> - unsigned long *apm,
> - unsigned long *aqm)
> +#define MDEV_IN_USE_ERR "Can not reserve queue %02lx.%04lx for host
> driver: " \
> + "in use by mdev"
> +
> +static void vfio_ap_mdev_log_sharing_err(struct ap_matrix_mdev
> *assignee,
> + struct ap_matrix_mdev *assigned_to,
> + unsigned long *apm, unsigned long *aqm)
> {
> unsigned long apid, apqi;
> - const struct device *dev = mdev_dev(matrix_mdev->mdev);
> - const char *mdev_name = dev_name(dev);
>
> for_each_set_bit_inv(apid, apm, AP_DEVICES)
> for_each_set_bit_inv(apqi, aqm, AP_DOMAINS)
> - dev_warn(dev, MDEV_SHARING_ERR, apid, apqi, mdev_name);
> + dev_warn(mdev_dev(assignee->mdev), MDEV_SHARING_ERR,
> + apid, apqi, dev_name(mdev_dev(assigned_to->mdev)));
> }
>
> -/**
> +static void vfio_ap_mdev_log_in_use_err(struct ap_matrix_mdev
> *assignee,
> + unsigned long *apm, unsigned long *aqm)
> +{
> + unsigned long apid, apqi;
> +
> + for_each_set_bit_inv(apid, apm, AP_DEVICES)
> + for_each_set_bit_inv(apqi, aqm, AP_DOMAINS)
> + dev_warn(mdev_dev(assignee->mdev), MDEV_IN_USE_ERR,
> + apid, apqi);
> +}
> +
> +/**assigned
> * vfio_ap_mdev_verify_no_sharing - verify APQNs are not shared by
> matrix mdevs
> *
> + * @assignee the matrix mdev to which @mdev_apm and @mdev_aqm are
> being
> + * assigned; or, NULL if this function was called by the AP
> bus driver
> + * in_use callback to verify none of the APQNs being
> reserved for the
> + * host device driver are in use by a vfio_ap mediated
> device
> * @mdev_apm: mask indicating the APIDs of the APQNs to be verified
> * @mdev_aqm: mask indicating the APQIs of the APQNs to be verified
> *
> - * Verifies that each APQN derived from the Cartesian product of a
> bitmap of
> - * AP adapter IDs and AP queue indexes is not configured for any
> matrix
> - * mediated device. AP queue sharing is not allowed.
> + * Verifies that each APQN derived from the Cartesian product of APIDs
> + * represented by the bits set in @mdev_apm and the APQIs of the bits
> set in
> + * @mdev_aqm is not assigned to a mediated device other than the mdev
> to which
> + * the APQN is being assigned (@assignee). AP queue sharing is not
> allowed.
> *
> * Return: 0 if the APQNs are not shared; otherwise return
> -EADDRINUSE.
> */
> -static int vfio_ap_mdev_verify_no_sharing(unsigned long *mdev_apm,
> +static int vfio_ap_mdev_verify_no_sharing(struct ap_matrix_mdev
> *assignee,
> + unsigned long *mdev_apm,
> unsigned long *mdev_aqm)
> {
> - struct ap_matrix_mdev *matrix_mdev;
> + struct ap_matrix_mdev *assigned_to;
> DECLARE_BITMAP(apm, AP_DEVICES);
> DECLARE_BITMAP(aqm, AP_DOMAINS);
>
> - list_for_each_entry(matrix_mdev, &matrix_dev->mdev_list, node) {
> + list_for_each_entry(assigned_to, &matrix_dev->mdev_list, node) {
> /*
> - * If the input apm and aqm are fields of the matrix_mdev
> - * object, then move on to the next matrix_mdev.
> + * If the mdev to which the mdev_apm and mdev_aqm is being
> + * assigned is the same as the mdev being verified
> */
> - if (mdev_apm == matrix_mdev->matrix.apm &&
> - mdev_aqm == matrix_mdev->matrix.aqm)
> + if (assignee == assigned_to)
> continue;
>
> memset(apm, 0, sizeof(apm));
> @@ -912,17 +930,21 @@ static int
> vfio_ap_mdev_verify_no_sharing(unsigned long *mdev_apm,
>
> /*
> * We work on full longs, as we can only exclude the leftover
> - * bits in non-inverse order. The leftover is all zeros.
> + * bits in non-inverse order. The leftover is all zeros.assigned
> */
> - if (!bitmap_and(apm, mdev_apm, matrix_mdev->matrix.apm,
> + if (!bitmap_and(apm, mdev_apm, assigned_to->matrix.apm,
> AP_DEVICES))
> continue;
>
> - if (!bitmap_and(aqm, mdev_aqm, matrix_mdev->matrix.aqm,
> + if (!bitmap_and(aqm, mdev_aqm, assigned_to->matrix.aqm,
> AP_DOMAINS))
> continue;
>
> - vfio_ap_mdev_log_sharing_err(matrix_mdev, apm, aqm);
> + if (assignee)
> + vfio_ap_mdev_log_sharing_err(assignee, assigned_to,
> + apm, aqm);
> + else
> + vfio_ap_mdev_log_in_use_err(assigned_to, apm, aqm);
>
> return -EADDRINUSE;
> }
> @@ -951,7 +973,8 @@ static int vfio_ap_mdev_validate_masks(struct
> ap_matrix_mdev *matrix_mdev)
> matrix_mdev->matrix.aqm))
> return -EADDRNOTAVAIL;
>
> - return vfio_ap_mdev_verify_no_sharing(matrix_mdev->matrix.apm,
> + return vfio_ap_mdev_verify_no_sharing(matrix_mdev,
> + matrix_mdev->matrix.apm,
> matrix_mdev->matrix.aqm);
> }
>
> @@ -2458,7 +2481,7 @@ int vfio_ap_mdev_resource_in_use(unsigned long
> *apm, unsigned long *aqm)
>
> mutex_lock(&matrix_dev->guests_lock);
> mutex_lock(&matrix_dev->mdevs_lock);
> - ret = vfio_ap_mdev_verify_no_sharing(apm, aqm);
> + ret = vfio_ap_mdev_verify_no_sharing(NULL, apm, aqm);
> mutex_unlock(&matrix_dev->mdevs_lock);
> mutex_unlock(&matrix_dev->guests_lock);

I don't see exactly where you do the printk but according to your
description you do an error log. I would suggest to lower this
to a warning instead.