linux-kernel - Re: [PATCH v11 13/26] s390: vfio-ap: zeroize the AP queues

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Date:   Wed, 26 Sep 2018 20:58:41 +0200
From:   Christian Borntraeger <borntraeger@...ibm.com>
To:     Cornelia Huck <cohuck@...hat.com>,
        Tony Krowiak <akrowiak@...ux.vnet.ibm.com>
Cc:     linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, freude@...ibm.com, schwidefsky@...ibm.com,
        heiko.carstens@...ibm.com, kwankhede@...dia.com,
        bjsdjshi@...ux.vnet.ibm.com, pbonzini@...hat.com,
        alex.williamson@...hat.com, pmorel@...ux.vnet.ibm.com,
        alifm@...ux.vnet.ibm.com, mjrosato@...ux.vnet.ibm.com,
        jjherne@...ux.vnet.ibm.com, thuth@...hat.com,
        pasic@...ux.vnet.ibm.com, berrange@...hat.com,
        fiuczy@...ux.vnet.ibm.com, buendgen@...ibm.com,
        frankja@...ux.ibm.com, Tony Krowiak <akrowiak@...ux.ibm.com>
Subject: Re: [PATCH v11 13/26] s390: vfio-ap: zeroize the AP queues



On 09/26/2018 03:38 PM, Cornelia Huck wrote:
> On Tue, 25 Sep 2018 19:16:28 -0400
> Tony Krowiak <akrowiak@...ux.vnet.ibm.com> wrote:
> 
>> From: Tony Krowiak <akrowiak@...ux.ibm.com>
>>
>> Let's call PAPQ(ZAPQ) to zeroize a queue for each queue configured
>> for a mediated matrix device when it is released.
>>
>> Zeroizing a queue resets the queue, clears all pending
>> messages for the queue entries and disables adapter interruptions
>> associated with the queue.
>>
>> Signed-off-by: Tony Krowiak <akrowiak@...ux.ibm.com>
>> Reviewed-by: Halil Pasic <pasic@...ux.ibm.com>
>> Tested-by: Michael Mueller <mimu@...ux.ibm.com>
>> Tested-by: Farhan Ali <alifm@...ux.ibm.com>
>> ---
>>  drivers/s390/crypto/vfio_ap_ops.c | 44 +++++++++++++++++++++++++++++++
>>  1 file changed, 44 insertions(+)
>>
>> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
>> index b4f67d547493..1943e47d7d78 100644
>> --- a/drivers/s390/crypto/vfio_ap_ops.c
>> +++ b/drivers/s390/crypto/vfio_ap_ops.c
>> @@ -816,6 +816,49 @@ static int vfio_ap_mdev_group_notifier(struct notifier_block *nb,
>>  	return NOTIFY_OK;
>>  }
>>  
>> +static int vfio_ap_mdev_reset_queue(unsigned int apid, unsigned int apqi,
>> +				    unsigned int retry)
>> +{
>> +	struct ap_queue_status status;
>> +
>> +	do {
>> +		status = ap_zapq(AP_MKQID(apid, apqi));
>> +		switch (status.response_code) {
>> +		case AP_RESPONSE_NORMAL:
>> +			return 0;
>> +		case AP_RESPONSE_RESET_IN_PROGRESS:
>> +		case AP_RESPONSE_BUSY:
>> +			msleep(20);
>> +			break;
>> +		default:
>> +			/* things are really broken, give up */
>> +			return -EIO;
>> +		}
>> +	} while (retry--);
>> +
>> +	return -EBUSY;
>> +}
>> +
>> +static int vfio_ap_mdev_reset_queues(struct mdev_device *mdev)
>> +{
>> +	int ret;
>> +	int rc = 0;
>> +	unsigned long apid, apqi;
>> +	struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
>> +
>> +	for_each_set_bit_inv(apid, matrix_mdev->matrix.apm,
>> +			     matrix_mdev->matrix.apm_max + 1) {
>> +		for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm,
>> +				     matrix_mdev->matrix.aqm_max + 1) {
>> +			ret = vfio_ap_mdev_reset_queue(apid, apqi, 1);
> 
> I'd still like to see a comment here:
> 
> /*
>  * Regardless whether a queue turns out to be busy, or is not
>  * operational, we need to continue resetting the remaining
>  * queues.
>  */

I added your proposal to the apv11 branch.