Re: [PATCH v9 17/22] s390: vfio-ap: zeroize the AP queues.

Tony Krowiak
2018-08-15T20:36:32Z

On 08/15/2018 12:24 PM, Cornelia Huck wrote:
> On Mon, 13 Aug 2018 17:48:14 -0400
> Tony Krowiak <akrowiak@linux.vnet.ibm.com> wrote:
>
> Nit: please drop the leading period in the subject.

I assume you mean the ending period?

>
>> From: Tony Krowiak <akrowiak@linux.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@linux.ibm.com>
>> Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
>> Tested-by: Michael Mueller <mimu@linux.ibm.com>
>> Tested-by: Farhan Ali <alifm@linux.ibm.com>
>> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
>> ---
>> drivers/s390/crypto/vfio_ap_ops.c | 25 +++++++++++++++++++++++++
>> drivers/s390/crypto/vfio_ap_private.h | 25 +++++++++++++++++++++++++
>> 2 files changed, 50 insertions(+), 0 deletions(-)
>>
>> diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
>> index 3e8534b..34f982a 100644
>> --- a/drivers/s390/crypto/vfio_ap_private.h
>> +++ b/drivers/s390/crypto/vfio_ap_private.h
>> @@ -74,4 +74,29 @@ struct ap_matrix_mdev {
>> extern int vfio_ap_mdev_register(void);
>> extern void vfio_ap_mdev_unregister(void);
>>
>> +static inline int vfio_ap_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:
>> + pr_warn("%s: error zeroizing %02x.%04x: response code %d\n",
>> + VFIO_AP_MODULE_NAME, apid, apqi,
>> + status.response_code);
> How can we end up here? Does this mean that we just don't know what to
> do with this response, or is this something that should never happen?
> (How much sense does it make to print an error?)

There are additional response codes that could be returned; for example,
in the case of a catastrophic failure such as: The function can not be
performed because the AP was somehow deconfigured or the functiona
cannot be performed due to a machine check failure that caused the AP
path to be removed. It shouldn't happen, but all are possibilities.
I can get rid of the message and just return -EIO if you prefer.

>
>> + return -EIO;
>> + }
>> + } while (retry--);
>> +
>> + return -EBUSY;
>> +}
>> +
>> #endif /* _VFIO_AP_PRIVATE_H_ */