Re: [PATCH v2 4/7] s390: vfio-ap: allow assignment of unavailable AP resources to mdev device

[Tony Krowiak <akrowiak@linux.ibm.com>]

On 5/6/19 3:05 AM, Pierre Morel wrote:
> On 03/05/2019 23:14, Tony Krowiak wrote:
>> The AP architecture does not preclude assignment of AP resources that are
>> not yet in the AP configuration (i.e., not available or not online).
>> Let's go ahead and implement this facet of the AP architecture for linux
>> guests.
>>
>> The current implementation does not allow assignment of AP resources to
>> an mdev device if the AP queue devices identified by the assignment are
>> not bound to the vfio_ap device driver. This patch allows assignment 
>> of AP
>> resources to the mdev device even if the AP queue devices are not 
>> bound to
>> the vfio_ap device driver, as long as the AP queue devices are not
>> reserved by the AP BUS for use by the zcrypt device drivers.
> 
> or another mediated device.

Right you are!!

> 
> 
>>
>> Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
>> ---
>>   drivers/s390/crypto/vfio_ap_ops.c | 231 
>> ++++++++------------------------------
>>   1 file changed, 44 insertions(+), 187 deletions(-)
>>
>> diff --git a/drivers/s390/crypto/vfio_ap_ops.c 
>> b/drivers/s390/crypto/vfio_ap_ops.c
>> index 1021466cb661..ea24caf17a16 100644
>> --- a/drivers/s390/crypto/vfio_ap_ops.c
>> +++ b/drivers/s390/crypto/vfio_ap_ops.c
>> @@ -113,122 +113,6 @@ static struct attribute_group 
>> *vfio_ap_mdev_type_groups[] = {
>>       NULL,
>>   };
>> -struct vfio_ap_queue_reserved {
>> -    unsigned long *apid;
>> -    unsigned long *apqi;
>> -    bool reserved;
>> -};
>> -
>> -/**
>> - * vfio_ap_has_queue
>> - *
>> - * @dev: an AP queue device
>> - * @data: a struct vfio_ap_queue_reserved reference
>> - *
>> - * Flags whether the AP queue device (@dev) has a queue ID containing 
>> the APQN,
>> - * apid or apqi specified in @data:
>> - *
>> - * - If @data contains both an apid and apqi value, then @data will 
>> be flagged
>> - *   as reserved if the APID and APQI fields for the AP queue device 
>> matches
>> - *
>> - * - If @data contains only an apid value, @data will be flagged as
>> - *   reserved if the APID field in the AP queue device matches
>> - *
>> - * - If @data contains only an apqi value, @data will be flagged as
>> - *   reserved if the APQI field in the AP queue device matches
>> - *
>> - * Returns 0 to indicate the input to function succeeded. Returns 
>> -EINVAL if
>> - * @data does not contain either an apid or apqi.
>> - */
>> -static int vfio_ap_has_queue(struct device *dev, void *data)
>> -{
>> -    struct vfio_ap_queue_reserved *qres = data;
>> -    struct ap_queue *ap_queue = to_ap_queue(dev);
>> -    ap_qid_t qid;
>> -    unsigned long id;
>> -
>> -    if (qres->apid && qres->apqi) {
>> -        qid = AP_MKQID(*qres->apid, *qres->apqi);
>> -        if (qid == ap_queue->qid)
>> -            qres->reserved = true;
>> -    } else if (qres->apid && !qres->apqi) {
>> -        id = AP_QID_CARD(ap_queue->qid);
>> -        if (id == *qres->apid)
>> -            qres->reserved = true;
>> -    } else if (!qres->apid && qres->apqi) {
>> -        id = AP_QID_QUEUE(ap_queue->qid);
>> -        if (id == *qres->apqi)
>> -            qres->reserved = true;
>> -    } else {
>> -        return -EINVAL;
>> -    }
>> -
>> -    return 0;
>> -}
>> -
>> -/**
>> - * vfio_ap_verify_queue_reserved
>> - *
>> - * @matrix_dev: a mediated matrix device
>> - * @apid: an AP adapter ID
>> - * @apqi: an AP queue index
>> - *
>> - * Verifies that the AP queue with @apid/@apqi is reserved by the 
>> VFIO AP device
>> - * driver according to the following rules:
>> - *
>> - * - If both @apid and @apqi are not NULL, then there must be an AP 
>> queue
>> - *   device bound to the vfio_ap driver with the APQN identified by 
>> @apid and
>> - *   @apqi
>> - *
>> - * - If only @apid is not NULL, then there must be an AP queue device 
>> bound
>> - *   to the vfio_ap driver with an APQN containing @apid
>> - *
>> - * - If only @apqi is not NULL, then there must be an AP queue device 
>> bound
>> - *   to the vfio_ap driver with an APQN containing @apqi
>> - *
>> - * Returns 0 if the AP queue is reserved; otherwise, returns 
>> -EADDRNOTAVAIL.
>> - */
>> -static int vfio_ap_verify_queue_reserved(unsigned long *apid,
>> -                     unsigned long *apqi)
>> -{
>> -    int ret;
>> -    struct vfio_ap_queue_reserved qres;
>> -
>> -    qres.apid = apid;
>> -    qres.apqi = apqi;
>> -    qres.reserved = false;
>> -
>> -    ret = driver_for_each_device(&matrix_dev->vfio_ap_drv->driver, NULL,
>> -                     &qres, vfio_ap_has_queue);
>> -    if (ret)
>> -        return ret;
>> -
>> -    if (qres.reserved)
>> -        return 0;
>> -
>> -    return -EADDRNOTAVAIL;
>> -}
>> -
>> -static int
>> -vfio_ap_mdev_verify_queues_reserved_for_apid(struct ap_matrix_mdev 
>> *matrix_mdev,
>> -                         unsigned long apid)
>> -{
>> -    int ret;
>> -    unsigned long apqi;
>> -    unsigned long nbits = matrix_mdev->matrix.aqm_max + 1;
>> -
>> -    if (find_first_bit_inv(matrix_mdev->matrix.aqm, nbits) >= nbits)
>> -        return vfio_ap_verify_queue_reserved(&apid, NULL);
>> -
>> -    for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm, nbits) {
>> -        ret = vfio_ap_verify_queue_reserved(&apid, &apqi);
>> -        if (ret)
>> -            return ret;
>> -    }
>> -
>> -    return 0;
>> -}
>> -
>>   /**
>>    * vfio_ap_mdev_verify_no_sharing
>>    *
>> @@ -236,18 +120,26 @@ 
>> vfio_ap_mdev_verify_queues_reserved_for_apid(struct ap_matrix_mdev 
>> *matrix_mdev,
>>    * and AP queue indexes comprising the AP matrix are not configured 
>> for another
>>    * mediated device. AP queue sharing is not allowed.
>>    *
>> - * @matrix_mdev: the mediated matrix device
>> + * @mdev_apm: the mask identifying the adapters assigned to mdev
>> + * @mdev_apm: the mask identifying the adapters assigned to mdev
>>    *
>>    * Returns 0 if the APQNs are not shared, otherwise; returns 
>> -EADDRINUSE.
>>    */
>> -static int vfio_ap_mdev_verify_no_sharing(struct ap_matrix_mdev 
>> *matrix_mdev)
>> +static int vfio_ap_mdev_verify_no_sharing(unsigned long *mdev_apm,
>> +                      unsigned long *mdev_aqm)
>>   {
>>       struct ap_matrix_mdev *lstdev;
>>       DECLARE_BITMAP(apm, AP_DEVICES);
>>       DECLARE_BITMAP(aqm, AP_DOMAINS);
>>       list_for_each_entry(lstdev, &matrix_dev->mdev_list, node) {
>> -        if (matrix_mdev == lstdev)
>> +        /*
>> +         * If either of the input masks belongs to the mdev to which an
>> +         * AP resource is being assigned, then we don't need to verify
>> +         * that mdev's masks.
>> +         */
>> +        if ((mdev_apm == lstdev->matrix.apm) ||
>> +            (mdev_aqm == lstdev->matrix.aqm))
>>               continue;
> 
> Is it possible that mdev_apm and mdev_aqm do not belong to the same 
> mediated device?

The mdev_apm and the mdev_aqm will not both belong to the same mdev
device. Either the mdev_apm OR the mdev_aqm will belong to the mdev
device to which the adapter or domain is being assigned.

When an adapter is assigned, the mdev_apm is allocated in the
assign_adapter_store function setting only the bit corresponding to
the APID of the adapter being assigned. The mdev_aqm address is the
address of the matrix_mdev->matrix.aqm.

When a domain is assigned, the mdev_aqm is allocated in the
assign_adapter_store function setting only the bit corresponding to
the APQI of the domain being assigned. The mdev_apm address is the
address of the matrix_mdev->matrix.apm.

> 
> ...snip...
> 
>