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SubjectRe: [PATCH v3 09/14] s390: vfio-ap: sysfs interfaces to configure domains
On Wed, 14 Mar 2018 14:25:49 -0400
Tony Krowiak <akrowiak@linux.vnet.ibm.com> wrote:

> Provides the sysfs interfaces for assigning AP domains to
> and unassigning AP domains from a mediated matrix device.
>
> An AP domain ID corresponds to an AP queue index (APQI). For
> each domain assigned to the mediated matrix device, its
> corresponging APQI is stored in an AP queue mask (AQM).
> The bits in the AQM, from most significant to least
> significant bit, correspond to AP domain numbers 0 to 255.
> When a domain is assigned, the bit corresponding to its
> APQI will be set in the AQM. Likewise, when a domain is
> unassigned, the bit corresponding to its APQI will be
> cleared from the AQM.
>
> The relevant sysfs structures are:
>
> /sys/devices/vfio_ap
> ... [matrix]
> ...... [mdev_supported_types]
> ......... [vfio_ap-passthrough]
> ............ [devices]
> ...............[$uuid]
> .................. assign_domain
> .................. unassign_domain
>
> To assign a domain to the $uuid mediated matrix device,
> write the domain's ID to the assign_domain file. To
> unassign a domain, write the domain's ID to the
> unassign_domain file. The ID is specified using
> conventional semantics: If it begins with 0x, the number
> will be parsed as a hexadecimal (case insensitive) number;
> otherwise, it will be parsed as a decimal number.
>
> For example, to assign domain 173 (0xad) to the mediated matrix
> device $uuid:
>
> echo 173 > assign_domain
>
> or
>
> echo 0xad > assign_domain
>
> To unassign domain 173 (0xad):
>
> echo 173 > unassign_domain
>
> or
>
> echo 0xad > unassign_domain
>
> The assignment will be rejected:
>
> * If the domain ID exceeds the maximum value for an AP domain:
>
> * If the AP Extended Addressing (APXA) facility is installed,
> the max value is 255
>
> * Else the max value is 15
>
> * If no AP adapters have yet been assigned and there are
> no AP queues reserved by the VFIO AP driver that have an APQN
> with an APQI matching that of the AP domain number being
> assigned.
>
> * If any of the APQNs that can be derived from the intersection
> of the APQI being assigned and the AP adapter ID (APID) of
> each of the AP adapters previously assigned can not be matched
> with an APQN of an AP queue device reserved by the VFIO AP
> driver.
>
> Signed-off-by: Tony Krowiak <akrowiak@linux.vnet.ibm.com>
> ---
> arch/s390/include/asm/kvm-ap.h | 1 +
> drivers/s390/crypto/vfio_ap_ops.c | 215 ++++++++++++++++++++++++++++++++++++-
> 2 files changed, 215 insertions(+), 1 deletions(-)
>

> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
> index 90512a6..c448835 100644
> --- a/drivers/s390/crypto/vfio_ap_ops.c
> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> @@ -377,10 +377,223 @@ static ssize_t unassign_adapter_store(struct device *dev,
> }
> DEVICE_ATTR_WO(unassign_adapter);
>
> +/**
> + * vfio_ap_validate_queues_for_apqi
> + *
> + * @ap_matrix: the matrix device
> + * @matrix_mdev: the mediated matrix device
> + * @apqi: an AP queue index (APQI) - corresponds to a domain ID
> + *
> + * Verifies that each APQN that is derived from the intersection of @apqi and
> + * each AP adapter ID (APID) corresponding to an AP domain assigned to the
> + * @matrix_mdev matches the APQN of an AP queue reserved by the VFIO AP device
> + * driver.
> + *
> + * Returns 0 if validation succeeds; otherwise, returns an error.
> + */
> +static int vfio_ap_validate_queues_for_apqi(struct ap_matrix *ap_matrix,
> + struct ap_matrix_mdev *matrix_mdev,
> + unsigned long apqi)
> +{
> + int ret;
> + struct vfio_ap_qid_match qid_match;
> + unsigned long apid;
> + struct device_driver *drv = ap_matrix->device.driver;
> +
> + /**
> + * Examine each APQN with the specified APQI
> + */
> + for_each_set_bit_inv(apid, matrix_mdev->matrix->apm,
> + matrix_mdev->matrix->apm_max) {
> + qid_match.qid = AP_MKQID(apid, apqi);
> + qid_match.dev = NULL;
> +
> + ret = driver_for_each_device(drv, NULL, &qid_match,
> + vfio_ap_queue_match);
> + if (ret)
> + return ret;

Hm, I'm wondering whether jumping out of the outer loop is the correct
thing to do here - and if yes, whether we should log an error?

> +
> + /*
> + * If the APQN identifies an AP queue that is reserved by the
> + * VFIO AP device driver, continue processing.
> + */
> + if (qid_match.dev)
> + continue;
> +
> + pr_err("%s: AP queue %02lx.%04lx not reserved by %s driver",
> + VFIO_AP_MATRIX_MODULE_NAME, apqi, apqi,
> + VFIO_AP_DRV_NAME);
> +
> + return -ENXIO;
> + }
> +
> + return 0;
> +}

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