Re: [PATCH v6 11/21] s390: vfio-ap: sysfs interfaces to configure domains

[Pierre Morel <pmorel@linux.ibm.com>]

On 29/06/2018 23:11, Tony Krowiak 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;
> if it begins with 0, it will be parsed as an octal 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 0255 > assign_domain
>
> 	or
>
> 	echo 0xad > assign_domain
>
> To unassign domain 173 (0xad):
>
> 	echo 173 > unassign_domain
>
> 	or
>
> 	echo 0255 > 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.ibm.com>
> ---
>   drivers/s390/crypto/vfio_ap_ops.c |  173 ++++++++++++++++++++++++++++++++++++-
>   1 files changed, 172 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
> index a4351bd..a5b06e7 100644
> --- a/drivers/s390/crypto/vfio_ap_ops.c
> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> @@ -170,6 +170,27 @@ static int vfio_ap_queue_has_apid(struct device *dev, void *data)
>   }
>
>   /**
> + * vfio_ap_queue_has_apqi
> + *
> + * @dev: an AP queue device
> + * @data: an AP queue index
> + *
> + * Flags whether any AP queue device has a particular AP queue index
> + *
> + * Returns 0 to indicate the function succeeded
> + */
> +static int vfio_ap_queue_has_apqi(struct device *dev, void *data)
> +{
> +	struct vfio_id_reserved *id_res = data;
> +	struct ap_queue *ap_queue = to_ap_queue(dev);
> +
> +	if (id_res->id == AP_QID_QUEUE(ap_queue->qid))
> +		id_res->reserved = true;
> +
> +	return 0;
> +}
> +
> +/**
>    * vfio_ap_verify_qid_reserved
>    *
>    * @matrix_dev: a mediated matrix device
> @@ -236,6 +257,42 @@ static int vfio_ap_verify_apid_reserved(struct ap_matrix_dev *matrix_dev,
>   	return -EPERM;
>   }
>
> +/**
> + * vfio_ap_verify_apqi_reserved
> + *
> + * @matrix_dev: a mediated matrix device
> + * @apqi: an AP queue index
> + *
> + * Verifies that an AP queue with @apqi is reserved by the VFIO AP device
> + * driver.
> + *
> + * Returns 0 if an AP queue with @apqi is reserved; otherwise, returns -ENODEV.
> + */
> +static int vfio_ap_verify_apqi_reserved(struct ap_matrix_dev *matrix_dev,
> +					const char *mdev_name,
> +					unsigned long apqi)
> +{
> +	int ret;
> +	struct vfio_id_reserved id_res;
> +
> +	id_res.id = apqi;
> +	id_res.reserved = false;
> +
> +	ret = driver_for_each_device(matrix_dev->device.driver, NULL, &id_res,
> +				     vfio_ap_queue_has_apqi);
> +	if (ret)
> +		return ret;
> +
> +	if (id_res.reserved)
> +		return 0;
> +
> +	pr_err("%s: mdev %s using queue %04lx not reserved by %s driver",
> +					VFIO_AP_MODULE_NAME, mdev_name, apqi,
> +					VFIO_AP_DRV_NAME);
> +
> +	return -EPERM;
> +}
> +
>   static int vfio_ap_verify_queues_reserved(struct ap_matrix_dev *matrix_dev,
>   					  const char *mdev_name,
>   					  struct ap_matrix *matrix)
> @@ -417,10 +474,124 @@ static ssize_t unassign_adapter_store(struct device *dev,
>   }
>   DEVICE_ATTR_WO(unassign_adapter);
>
> +/**
> + * vfio_ap_validate_apqi
> + *
> + * @matrix_mdev: the mediated matrix device
> + * @apqi: the APQI (domain ID) to validate
> + *
> + * Validates the value of @apqi:
> + *	* If there are no AP adapters assigned, then there must be at least
> + *	  one AP queue device reserved by the VFIO AP device driver with an
> + *	  APQN containing @apqi.

Same as in preceding patch, I do not understand why you need this.

Pierre


-- 
Pierre Morel
Linux/KVM/QEMU in Böblingen - Germany